Line 1: | Line 1: | ||
− | {{SDU-Denmark/navbar}} | + | {{SDU-Denmark/navbar}} |
<html> | <html> | ||
Line 63: | Line 63: | ||
<div id="homePageCloud4" class="homeCloud"> | <div id="homePageCloud4" class="homeCloud"> | ||
<object id="homeCloud4" class="highlighted-image" data="https://static.igem.org/mediawiki/2017/3/38/T--SDU-Denmark--HomeCloud4.svg" type="image/svg+xml"></object> | <object id="homeCloud4" class="highlighted-image" data="https://static.igem.org/mediawiki/2017/3/38/T--SDU-Denmark--HomeCloud4.svg" type="image/svg+xml"></object> | ||
+ | </div> | ||
+ | <div id="homePageCloud5" class="homeCloud"> | ||
+ | <object id="homeCloud5" class="highlighted-image" data="https://static.igem.org/mediawiki/2017/1/15/T--SDU-Denmark--ar-plane.svg" type="image/svg+xml"></object> | ||
</div> | </div> | ||
</div> | </div> | ||
Line 94: | Line 97: | ||
<h3><span class="highlighted">Abstract</span></h3> | <h3><span class="highlighted">Abstract</span></h3> | ||
<hr> | <hr> | ||
− | <p><span class="highlighted"> | + | <p><span class="highlighted">With the PowerLeaf, iGEM SDU is introducing a novel solution for long-term storage of solar energy, becoming an alternative to solar cells</span>, without using environmentally harmful resources. We aim to accomplish this through the creation of a device visually shaped to resemble a leaf, thus providing a nature-in-city ambience. The team invested heavily in public engagement and collaborations to investigate how the device hypothetically could be implemented into an urban environment. From a technical perspective, <span class="highlighted">the bacterial solar battery is composed of an energy storing unit and an energy converting unit</span>. The energy storing unit is defined by a genetically engineered <i>Escherichia coli</i>, that fixates carbon dioxide into the chemically stable polymer cellulose, while the energy converting unit uses genetically engineered <i>E. coli</i> to consume the stored cellulose. Electrons retrieved from this process, are transferred to an anode by optimised nanowires, thereby creating an electrical current. Last but not least; the energy storing unit has a light-dependent system which activates dormancy during nighttime to reduce energy lost by metabolism. |
</p> | </p> | ||
Line 113: | Line 116: | ||
<div class="col-xs-1 verticalAlignColumnsAbstract"></div> | <div class="col-xs-1 verticalAlignColumnsAbstract"></div> | ||
<div class="col-xs-2 verticalAlignColumnsAbstract" style="text-align:center;"><a href="https://www.ingenco2.dk/crt/dispcust/c/4676/l/1" target="_blank"><img class="highlighted-image" src="https://static.igem.org/mediawiki/2017/9/9c/T--SDU-Denmark--co2-neutral-website.png" width="60%"/></a></div> | <div class="col-xs-2 verticalAlignColumnsAbstract" style="text-align:center;"><a href="https://www.ingenco2.dk/crt/dispcust/c/4676/l/1" target="_blank"><img class="highlighted-image" src="https://static.igem.org/mediawiki/2017/9/9c/T--SDU-Denmark--co2-neutral-website.png" width="60%"/></a></div> | ||
− | <div class="col-xs-6 verticalAlignColumnsAbstract"><div style="text-align:center;"><p>A green project, a <span class="btn-link btn-lg" data-toggle="modal" data-target="#about-our-green-wiki">green wiki</span>, and | + | <div class="col-xs-6 verticalAlignColumnsAbstract"><div style="text-align:center;"><p>A green project, a <span class="btn-link btn-lg" data-toggle="modal" data-target="#about-our-green-wiki">green wiki</span>, and a great performance in the <span class="btn-link btn-lg" data-toggle="modal" data-target="#about-igem-goes-green">iGEM Goes Green</span> initiative! Green just got greener.</p></div></div> |
<div class="col-xs-2 verticalAlignColumnsAbstract" style="text-align:center;"><img class="highlighted-image" src="https://static.igem.org/mediawiki/2017/e/e3/T--SDU-Denmark--igem-goes-green.png" width="50%"/></div> | <div class="col-xs-2 verticalAlignColumnsAbstract" style="text-align:center;"><img class="highlighted-image" src="https://static.igem.org/mediawiki/2017/e/e3/T--SDU-Denmark--igem-goes-green.png" width="50%"/></div> | ||
<div class="col-xs-1 verticalAlignColumnsAbstract"></div> | <div class="col-xs-1 verticalAlignColumnsAbstract"></div> | ||
Line 132: | Line 135: | ||
<div class="col-md-10"> | <div class="col-md-10"> | ||
− | <p>Our project is all about ensuring a greener and more sustainable future for ourselves and the coming generations. This of course meant, that our wiki had to to follow this purpose as well.CO<sub>2</sub> | + | <p>Our project is all about ensuring a greener and more sustainable future for ourselves and the coming generations. This of course meant, that our wiki had to to follow this purpose as well.CO<sub>2</sub> Neutral Website sponsored our wiki with a <a href="https://www.ingenco2.dk/crt/dispcust/c/4676/l/1 |
" target="_blank">CO<sub>2</sub> offset</a> equal to the amount of CO<sub>2</sub> produced by having the wiki running until October 31 2018. This does not mean the wiki is CO<sub>2</sub> neutral in itself, but that the offset, equal to its pollution, is compensated. Compensating an offset could for example be global initiatives like replacing stoves in Africa with energy efficient stoves and building new, renewable energy sources. Also companies will be instructed in reducing their CO<sub>2</sub> offset.</p> | " target="_blank">CO<sub>2</sub> offset</a> equal to the amount of CO<sub>2</sub> produced by having the wiki running until October 31 2018. This does not mean the wiki is CO<sub>2</sub> neutral in itself, but that the offset, equal to its pollution, is compensated. Compensating an offset could for example be global initiatives like replacing stoves in Africa with energy efficient stoves and building new, renewable energy sources. Also companies will be instructed in reducing their CO<sub>2</sub> offset.</p> | ||
Line 147: | Line 150: | ||
</div> | </div> | ||
</div> | </div> | ||
− | <!--End of modal | + | <!--End of modal about our green wiki--> |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
<!--Start of modal iGEM Goes Green--> | <!--Start of modal iGEM Goes Green--> | ||
<div class="modal fade" id="about-igem-goes-green" tabindex="-1" data-backdrop="false" style="background-color:rgba(0,0,0,0.6);"> | <div class="modal fade" id="about-igem-goes-green" tabindex="-1" data-backdrop="false" style="background-color:rgba(0,0,0,0.6);"> | ||
Line 360: | Line 171: | ||
<br> | <br> | ||
− | <p class="P-Larger"><b>The Collaboration</b></p | + | <p class="P-Larger"><b>The Collaboration</b></p> |
<p>As part of a Human Practices collaboration project the iGEM team of TU Dresden invited us to participate in iGEM Goes Green. The main idea of the collaboration is to calculate and consider the emission of CO<sub>2</sub> related to iGEM. | <p>As part of a Human Practices collaboration project the iGEM team of TU Dresden invited us to participate in iGEM Goes Green. The main idea of the collaboration is to calculate and consider the emission of CO<sub>2</sub> related to iGEM. | ||
<br> | <br> | ||
Line 368: | Line 179: | ||
<br> | <br> | ||
The estimated carbon footprint of a flight from Copenhagen, Denmark, to Boston, Massachusetts, USA and back again is 3.430 kg/person | The estimated carbon footprint of a flight from Copenhagen, Denmark, to Boston, Massachusetts, USA and back again is 3.430 kg/person | ||
− | <span class="reference"><span class="referencetext"><a target="blank" href="https://www.atmosfair.de/en/kompensieren/flug?locale=en&departure=CPH&arrival=BOS ">Flight emission calculator </a></span></span>. With a team of 14 individuals, this culminates in a total of 48.020 kg or roughly 48 tonnes of carbon dioxide for our team - just from flying intercontinental. Added to this is the carbon footprint of the Danish trains at 30 g/km/person <span class= | + | <span class="reference"><span class="referencetext"><a target="blank" href="https://www.atmosfair.de/en/kompensieren/flug?locale=en&departure=CPH&arrival=BOS ">Flight emission calculator </a></span></span>. With a team of 14 individuals, this culminates in a total of 48.020 kg or roughly 48 tonnes of carbon dioxide for our team - just from flying intercontinental. Added to this is the carbon footprint of the Danish trains at 30 g/km/person<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.dsb.dk/globalassets/arsrapport/2016/miljorapport-2016.pdf">DSB environmental report</a></span></span>. |
With the same 14 individuals and 175 km to Copenhagen from Odense this yields a total of 147 kg. | With the same 14 individuals and 175 km to Copenhagen from Odense this yields a total of 147 kg. | ||
− | We have been on a total of three trips, one to Langeland, Denmark, two to Copenhagen, Denmark, and one to Delft, Holland. We have travelled to these destinations in two Volkswagen Transporter vans. The carbon footprint of these is 188 kg/km/car | + | We have been on a total of three trips, one to Langeland, Denmark, two to Copenhagen, Denmark, and one to Delft, Holland. We have travelled to these destinations in two Volkswagen Transporter vans. The carbon footprint of these is 188 kg/km/car <span class=”reference”><span class="referencetext"><a target="blank" href="http://viewer.zmags.com/publication/4b44c1a8#/4b44c1a8/4">Volkswagen automobile details</a></span></span>. |
With a total of 2320 km travelled our trips yield a total of 844.5 kg of CO<sub>2</sub>. | With a total of 2320 km travelled our trips yield a total of 844.5 kg of CO<sub>2</sub>. | ||
<br> | <br> | ||
Thus our total carbon footprint of travelling is roughly 49 tonnes of CO<sub>2</sub>. | Thus our total carbon footprint of travelling is roughly 49 tonnes of CO<sub>2</sub>. | ||
<br> | <br> | ||
− | Regarding our wiki, we have received help from our sponsors CO<sub>2</sub> | + | Regarding our wiki, we have received help from our sponsors CO<sub>2</sub> Neutral Website in calculating the carbon footprint. They estimated roughly 10,000 views during the next year, but sponsored carbon elimination equivalent to 120,000 views. All in all the sponsorship from CO<sub>2</sub> Neutral Website has made our wiki net CO<sub>2</sub> negative. |
<br> | <br> | ||
− | We received a spreadsheet from TU-Dresden to estimate our carbon footprint from our lab <span class= | + | We received a spreadsheet from TU-Dresden to estimate our carbon footprint from our lab<span class=”reference”><span class="referencetext"><a target="blank" href="https://github.com/igem-dresden/GoGreenGuide/releases/tag/v1.0">Go Green Guide</a></span></span>. The carbon footprint calculated from our lab is estimated at a total of 1 tonne of CO<sub>2</sub>. |
<br> | <br> | ||
Thus our total carbon footprint is roughly 50 tonnes CO<sub>2</sub> | Thus our total carbon footprint is roughly 50 tonnes CO<sub>2</sub> | ||
− | </p> | + | </p> |
− | + | <p class="P-Larger"><b>Our Solution</b></p> | |
− | + | ||
− | <p class="P-Larger"><b>Our Solution</b></p | + | |
<p>To reduce our net carbon footprint we have made some local and one global initiative. | <p>To reduce our net carbon footprint we have made some local and one global initiative. | ||
The local initiatives are planting trees, buying green and travelling green. | The local initiatives are planting trees, buying green and travelling green. | ||
− | After thorough systematic research we could conclude that in general planting grass and most trees would increase our net carbon footprint, so we planted a few apple trees <span class= | + | After thorough systematic research we could conclude that in general planting grass and most trees would increase our net carbon footprint, so we planted a few apple trees<span class=”reference”><span class="referencetext"><a target="blank" href="https://www3.epa.gov/climatechange/Downloads/method-calculating-carbon-sequestration-trees-urban-and-suburban-settings.pdf">Carbon sequestration of trees</a></span></span> |
<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/?term=The+effects+of+household+management+practices+on+the+global+warming+potential+of+urban+lawns">Global warming and lawns</a></span></span> | <span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/?term=The+effects+of+household+management+practices+on+the+global+warming+potential+of+urban+lawns">Global warming and lawns</a></span></span> | ||
− | <span class="reference"><span class="referencetext"><a target="blank" href="https://www.researchgate.net/publication/237613871_Assessing_Soil_Carbon_Sequestration_in_Turfgrass_Systems_Using_Long-Term_Soil_Testing_Data ">Carbon sequestration in turfgrass</a></span></span>. | + | <span class="reference"><span class="referencetext"><a target="blank" href="https://www.researchgate.net/publication/237613871_Assessing_Soil_Carbon_Sequestration_in_Turfgrass_Systems_Using_Long-Term_Soil_Testing_Data">Carbon sequestration in turfgrass</a></span></span>. |
<br> | <br> | ||
Acknowledging this is not even cents on the dollar, we had to do more. Therefore some of the team changed their eating habits into a more local, organic and sustainable diet. The main focus of this diet was that a majority of the vegetables had to be local and should be picked up on nearby farms. For this reason one of the teammates signed up for “Odense Food Community” | Acknowledging this is not even cents on the dollar, we had to do more. Therefore some of the team changed their eating habits into a more local, organic and sustainable diet. The main focus of this diet was that a majority of the vegetables had to be local and should be picked up on nearby farms. For this reason one of the teammates signed up for “Odense Food Community” | ||
Line 396: | Line 205: | ||
Had we been able to go to Boston in a more eco-friendly way, we of course would. | Had we been able to go to Boston in a more eco-friendly way, we of course would. | ||
<br> | <br> | ||
− | Regarding global initiatives we started a partnership with CO<sub>2</sub> | + | Regarding global initiatives we started a partnership with CO<sub>2</sub> Neutral Website, which ended up in a sponsorship from them. What they have done in our name is</p> |
<ul class="list"> | <ul class="list"> | ||
<li>Build energy efficient stoves for families in Africa, reducing CO<sub>2</sub> emissions as less trees are logged. It also creates local jobs and creates a healthier life. Certified and audited through the Gold Standard.</li> | <li>Build energy efficient stoves for families in Africa, reducing CO<sub>2</sub> emissions as less trees are logged. It also creates local jobs and creates a healthier life. Certified and audited through the Gold Standard.</li> | ||
Line 404: | Line 213: | ||
<li>Help companies reduce their climate impact through energy efficiency.</li> | <li>Help companies reduce their climate impact through energy efficiency.</li> | ||
</ul> | </ul> | ||
− | <p>Thus we have had a global impact on climate, which cannot be estimated precisely.</p> | + | <p>Thus we have had a global impact on climate, which cannot be estimated precisely.</p> |
− | + | ||
<p class="P-Larger"><b>Conclusion</b></p><br class="miniBreak"> | <p class="P-Larger"><b>Conclusion</b></p><br class="miniBreak"> | ||
+ | |||
<p>In conclusion we would like to highlight the following</p> | <p>In conclusion we would like to highlight the following</p> | ||
<ul class="list"> | <ul class="list"> | ||
<li>Due to flying being a necessity for us when going to Boston we have a massive carbon footprint.</li> | <li>Due to flying being a necessity for us when going to Boston we have a massive carbon footprint.</li> | ||
<li>We acknowledge that any local initiative we have made are pennies on the dollar in regards to CO<sub>2</sub> emission and reduction.</li> | <li>We acknowledge that any local initiative we have made are pennies on the dollar in regards to CO<sub>2</sub> emission and reduction.</li> | ||
− | <li>The main initiative from us is the partnership with CO<sub>2</sub> | + | <li>The main initiative from us is the partnership with CO<sub>2</sub> Neutral Website, which has had a global impact.</li> |
Line 488: | Line 297: | ||
<div class="col-xs-8 verticalAlignColumns padding0 left right"> | <div class="col-xs-8 verticalAlignColumns padding0 left right"> | ||
<p class="P-Larger"><b><span class="highlighted">Bronze Medal Requirements</span></b><br class="shortBreak"> | <p class="P-Larger"><b><span class="highlighted">Bronze Medal Requirements</span></b><br class="shortBreak"> | ||
− | <p><b>Register and attend</b> – Our team applied on the 30<sup>th</sup> of March 2017 and got accepted the 4<sup>th</sup> of May 2017. We had an amazing summer and are looking forward to attend the Giant Jamboree!<br | + | <p><b>Register and attend</b> – Our team applied on the 30<sup>th</sup> of March 2017 and got accepted the 4<sup>th</sup> of May 2017. We had an amazing summer and are looking forward to attend the Giant Jamboree!<br> |
− | <b>Meet all the deliverables requirements</b> – You are reading the team wiki now, so that is one cat in the bag. You can find all attributions made to the project in the <a href="https://2017.igem.org/Team:SDU-Denmark#attributions" target="_blank">credits</a> section of the wiki. The team poster and team presentation are ready to be presented at the Giant Jamboree. We also filled the <a href="https://2017.igem.org/Safety/Final_Safety_Form?team_id=2449" target="_blank">safety form</a>, the <a href="https://igem.org/2017_Judging_Form?id=2449" target="_blank">judging form</a> and all our <a href="http://parts.igem.org/cgi/dna_transfer/batch_list.cgi?group_id=2951" target="_blank">parts</a> were registered and submitted in time.<br | + | <b>Meet all the deliverables requirements</b> – You are reading the team wiki now, so that is one cat in the bag. You can find all attributions made to the project in the <a href="https://2017.igem.org/Team:SDU-Denmark#attributions" target="_blank">credits</a> section of the wiki. The team poster and team presentation are ready to be presented at the Giant Jamboree. We also filled the <a href="https://2017.igem.org/Safety/Final_Safety_Form?team_id=2449" target="_blank">safety form</a>, the <a href="https://igem.org/2017_Judging_Form?id=2449" target="_blank">judging form</a> and all our <a href="http://parts.igem.org/cgi/dna_transfer/batch_list.cgi?group_id=2951" target="_blank">parts</a> were registered and submitted in time.<br> |
− | <b>Clearly state the Attributions</b> – All attributions made to our project have been clearly credited in the <a href="https://2017.igem.org/Team:SDU-Denmark#attributions" target="_blank">credits section</a>.<br | + | <b>Clearly state the Attributions</b> – All attributions made to our project have been clearly credited in the <a href="https://2017.igem.org/Team:SDU-Denmark#attributions" target="_blank">credits section</a>.<br> |
− | <b>Improve and/or characterise an existing Biobrick Part or Device</b> – The characterisation of the OmpR-regulated promoter <a href="http://parts.igem.org/Part:BBa_R0082" target="_blank">BBa_R0082</a> was improved, as the level of noise was studied on different vectors. <br> | + | <b>Improve and/or characterise an existing Biobrick Part or Device</b> – The characterisation of the OmpR-regulated promoter <a href="http://parts.igem.org/Part:BBa_R0082" target="_blank">BBa_R0082</a> was improved, as the level of noise was studied on different vectors. <br class="miniBreak"> |
− | Induction and inhibition of the pBAD promoter, <a href="http://parts.igem.org/Part:BBa_I0500" target="_blank">BBa_I0500</a>, were studied, whereby the characterisation of this part was improved. <br> | + | Induction and inhibition of the pBAD promoter, <a href="http://parts.igem.org/Part:BBa_I0500" target="_blank">BBa_I0500</a>, were studied, whereby the characterisation of this part was improved. <br class="miniBreak"> |
Furthermore, we characterized if the periplasmic beta-glucosidase could make <i>E. coli</i> live on cellobiose in fluid medium <a href="http://parts.igem.org/Part:BBa_K523014" target="_blank">BBa_K523014</a>, submitted by the <a href="https://2011.igem.org/Team:Edinburgh" target="_blank">2011 iGEM Edinburgh Team</a>. | Furthermore, we characterized if the periplasmic beta-glucosidase could make <i>E. coli</i> live on cellobiose in fluid medium <a href="http://parts.igem.org/Part:BBa_K523014" target="_blank">BBa_K523014</a>, submitted by the <a href="https://2011.igem.org/Team:Edinburgh" target="_blank">2011 iGEM Edinburgh Team</a>. | ||
− | The data obtained in these experiments are presented in the <a href="https://2017.igem.org/Team:SDU-Denmark#demonstration-and-results" target="_blank">demonstration and results section</a>.<br | + | The data obtained in these experiments are presented in the <a href="https://2017.igem.org/Team:SDU-Denmark#demonstration-and-results" target="_blank">demonstration and results section</a>.<br> |
</p> | </p> | ||
</div> | </div> | ||
Line 507: | Line 316: | ||
<div class="col-xs-8 verticalAlignColumns padding0 left"> | <div class="col-xs-8 verticalAlignColumns padding0 left"> | ||
<p class="P-Larger"><b><span class="highlighted">Silver Medal Requirements</span></b></p><br class="shortBreak"> | <p class="P-Larger"><b><span class="highlighted">Silver Medal Requirements</span></b></p><br class="shortBreak"> | ||
− | <p><b>Validated part/contribution</b> – We created the part <a href="http://parts.igem.org/Part:BBa_K2449004" target="_blank">BBa_K2449004</a>, containing a cellobiose phosphorylase. This enzyme enables <i>E. coli</i> to survive on cellobiose, which we validated by growth experiments. The data obtained in these experiments are presented in the <a href="https://2017.igem.org/Team:SDU-Denmark#demonstration-and-results" target="_blank">demonstration and results section</a>.<br | + | <p><b>Validated part/contribution</b> – We created the part <a href="http://parts.igem.org/Part:BBa_K2449004" target="_blank">BBa_K2449004</a>, containing a cellobiose phosphorylase. This enzyme enables <i>E. coli</i> to survive on cellobiose, which we validated by growth experiments. The data obtained in these experiments are presented in the <a href="https://2017.igem.org/Team:SDU-Denmark#demonstration-and-results" target="_blank">demonstration and results section</a>.<br> |
− | <b>Collaboration</b> – We have collaborated with several teams throughout our project by taking part in discussions, meetups, and answering questionnaires - we even hosted our first meetup for our fellow Danish iGEM teams. You will get to read all about this in the <a href="https://2017.igem.org/Team:SDU-Denmark#collaborations" target="_blank">credits section</a>.<br | + | <b>Collaboration</b> – We have collaborated with several teams throughout our project by taking part in discussions, meetups, and answering questionnaires - we even hosted our first meetup for our fellow Danish iGEM teams. You will get to read all about this in the <a href="https://2017.igem.org/Team:SDU-Denmark#collaborations" target="_blank">credits section</a>.<br> |
− | <b>Human Practices</b> – Our philosopher, historian, and biologist have discussed the <a href="https://2017.igem.org/Team:SDU-Denmark#bioethics" target="_blank">ethical and educational aspects</a> of our project in great detail. In extension to their work, we have been working extensively with <a href="https://2017.igem.org/Team:SDU-Denmark#education-and-public-engagement" target="_blank">public engagement and education</a>.<br | + | <b>Human Practices</b> – Our philosopher, historian, and biologist have discussed the <a href="https://2017.igem.org/Team:SDU-Denmark#bioethics" target="_blank">ethical and educational aspects</a> of our project in great detail. In extension to their work, we have been working extensively with <a href="https://2017.igem.org/Team:SDU-Denmark#education-and-public-engagement" target="_blank">public engagement and education</a>.<br> |
</p> | </p> | ||
</div> | </div> | ||
Line 524: | Line 333: | ||
<p class="P-Larger"><b><span class="highlighted">Gold Medal Requirements</span></b></p><br class="shortBreak"> | <p class="P-Larger"><b><span class="highlighted">Gold Medal Requirements</span></b></p><br class="shortBreak"> | ||
− | <p><b>Integrated Human Practices</b> – Regarding the <href="https://2017.igem.org/Team:SDU-Denmark#integrated-practices" target="_blank">development and implementation</a> of the device, we reached out to and remained in contact with city planners from our hometown throughout our project. This regarded advice and conversations on anything from the possible design, value, safety, use, placement, and plastic type of our device. We also made sure to integrate the findings of said conversations into our overall project. Last but not least, we focused on demonstrating this process on our wiki in order to inspire future iGEM teams.<br | + | <p><b>Integrated Human Practices</b> – Regarding the <href="https://2017.igem.org/Team:SDU-Denmark#integrated-practices" target="_blank">development and implementation</a> of the device, we reached out to and remained in contact with city planners from our hometown throughout our project. This regarded advice and conversations on anything from the possible design, value, safety, use, placement, and plastic type of our device. We also made sure to integrate the findings of said conversations into our overall project. Last but not least, we focused on demonstrating this process on our wiki in order to inspire future iGEM teams. <br> |
− | <b>Model your project</b> – Through extensive <a href="https://2017.igem.org/Team:SDU-Denmark#modelling" target="_blank">modelling</a>, we have learned that it is possible to regulate bacterial dormancy. However, the modelling showed that it would be inadequate to only regulate the toxin RelE, as this would make the bacteria unable to exit dormancy. To regulate dormancy properly, it would also require tight regulation of the antitoxin RelB. This information was used to shape the entire approach of the light-dependent dormancy system.<br | + | <b>Model your project</b> – Through extensive <a href="https://2017.igem.org/Team:SDU-Denmark#modelling" target="_blank">modelling</a>, we have learned that it is possible to regulate bacterial dormancy. However, the modelling showed that it would be inadequate to only regulate the toxin RelE, as this would make the bacteria unable to exit dormancy. To regulate dormancy properly, it would also require tight regulation of the antitoxin RelB. This information was used to shape the entire approach of the light-dependent dormancy system.<br> |
</p> | </p> | ||
Line 561: | Line 370: | ||
<div class="row"><div class="col-xs-12"> | <div class="row"><div class="col-xs-12"> | ||
<p class="P-Larger"><span class="highlighted"><b>A Global Problem</b></span></p> | <p class="P-Larger"><span class="highlighted"><b>A Global Problem</b></span></p> | ||
− | <p>In the world of today, <span class="highlighted">it is becoming increasingly important to ensure a sustainable future</span>. Not just for our generation, but especially for the generations to come, as their possibilities should not be limited by our choices. | + | <p>In the world of today, <span class="highlighted">it is becoming increasingly important to ensure a sustainable future</span><span class="reference"><span class="referencetext"><a target="blank" href="hhttp://wwwoecdorg/greengrowth/MATERIAL%20RESOURCES,%20PRODUCTIVITY%20AND%20THE%20ENVIRONMENT_key%20findingspdf"> Green Growth Papers (Myriam Linster). Material Resources, Productivity and the Environment. 2013.</a></span></span>. Not just for our generation, but especially for the generations to come, as their possibilities should not be limited by our choices. |
− | Our solution, is the development of a green and renewable technology, which offers new advantages to the field of sustainable energy. <span class="highlighted">There are currently certain limitations to the existing options for renewable energy</span>, namely the intermittency and the diluteness problem. The intermittency problem describes the discontinuous energy production, along with inefficient storage. On the other hand, the diluteness problem is characterised as the resource-demanding production of technical devices, such as solar cells and batteries. This means that a lack of resources eventually would eliminate the current forms of green technology. As such, we need to <span class="highlighted">introduce a new and sustainable approach to green energy</span> to ensure the continuation of our beautiful world for the coming generations. | + | Our solution, is the development of a green and renewable technology, which offers new advantages to the field of sustainable energy. <span class="highlighted">There are currently certain limitations to the existing options for renewable energy</span>, namely the intermittency and the diluteness problem<span class=”reference”><span class="referencetext"><a target="blank" href=" https://www.researchgate.net/publication/279212503_Global_Lithium_Resources_and_Sustainability_Issues"> Alexandre Chagnes JS. Global Lithium Resources and Sustainability Issues. Lithium Process Chemistry: Elsevier; June 2015. p. pp.1-40.</a></span></span>. The intermittency problem describes the discontinuous energy production, along with inefficient storage. On the other hand, the diluteness problem is characterised as the resource-demanding production of technical devices, such as solar cells and batteries. This means that a lack of resources eventually would eliminate the current forms of green technology. As such, we need to <span class="highlighted">introduce a new and sustainable approach to green energy</span> to ensure the continuation of our beautiful world for the coming generations. |
</p> | </p> | ||
<br class="noContent"> | <br class="noContent"> | ||
Line 569: | Line 378: | ||
<p>We are a team of young adults raised with an awareness of climate changes and the potential limitations to our ways of life. As a generation that appreciates open source and shared information, we have been encouraged to constantly challenge the ideas of yesterday. With this in mind, <span class="highlighted">we decided the best solution to the eventual energy crisis would be to seek out experts and the general public, even children, in order to rethink the current notion</span>; that the only way to save our planet is to compromise our living standards. | <p>We are a team of young adults raised with an awareness of climate changes and the potential limitations to our ways of life. As a generation that appreciates open source and shared information, we have been encouraged to constantly challenge the ideas of yesterday. With this in mind, <span class="highlighted">we decided the best solution to the eventual energy crisis would be to seek out experts and the general public, even children, in order to rethink the current notion</span>; that the only way to save our planet is to compromise our living standards. | ||
<br> | <br> | ||
− | Fortunately, we learned through interaction with local agents that a great deal of people share our belief; that <span class="highlighted">we ought to pursue the development of low energy cities with a high quality of life</span>. In fact, we even discovered that our own hometown Odense wants to be the greenest, most renewable city in Denmark by 2050 <span class= | + | Fortunately, we learned through interaction with local agents that a great deal of people share our belief; that <span class="highlighted">we ought to pursue the development of low energy cities with a high quality of life</span>. In fact, we even discovered that our own hometown Odense wants to be the greenest, most renewable city in Denmark by 2050<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.odense.dk/borger/miljoe-og-affald/klima">Odense Municipality’s website, regarding their politics on the current climate changes.</a></span></span>. |
<br> | <br> | ||
In the pursuit of this goal, <span class="highlighted">rose to the challenge of creating a truly green solution</span>, which would provide an environmental friendly source of energy. | In the pursuit of this goal, <span class="highlighted">rose to the challenge of creating a truly green solution</span>, which would provide an environmental friendly source of energy. | ||
<br> | <br> | ||
− | <span class="highlighted">Please keep scrolling if you wish to read more about our solution </span>, or go straight to <a href=”https://2017.igem.org/Team:SDU-Denmark#bioethics” target=”_blank”>bioethics</a> if you are curious why we not only <i>could</i>, but <i>ought</i> to do something about the current and forthcoming energy crisis. | + | <span class="highlighted">Please keep scrolling if you wish to read more about our solution</span>, or go straight to <a href=”https://2017.igem.org/Team:SDU-Denmark#bioethics” target=”_blank”>bioethics</a> if you are curious why we not only <i>could</i>, but <i>ought</i> to do something about the current and forthcoming energy crisis. |
</p> | </p> | ||
<br class="noContent"> | <br class="noContent"> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p class="P-Larger"><span class="highlighted"><b>Inspiration</b></span></p> | + | <div id="inspiration-from-children"><p class="P-Larger"><span class="highlighted"><b>Inspiration</b></span></p> |
<p>Our early ideas were reviewed after attending the Danish Science Festival, where we met several young minds with creative and inspiring ideas. The children came to our workshop with their parents to learn about bacteria, the history of GMO, ethics, and iGEM. They attended our “Draw-a-Bacteria”-competition, where they designed their own bacteria, some even with detailed stories. From this <span class="highlighted">the children taught us a thing or two about the endless possibilities of GMO</span>.</p> | <p>Our early ideas were reviewed after attending the Danish Science Festival, where we met several young minds with creative and inspiring ideas. The children came to our workshop with their parents to learn about bacteria, the history of GMO, ethics, and iGEM. They attended our “Draw-a-Bacteria”-competition, where they designed their own bacteria, some even with detailed stories. From this <span class="highlighted">the children taught us a thing or two about the endless possibilities of GMO</span>.</p> | ||
<br> | <br> | ||
Line 586: | Line 395: | ||
</div> | </div> | ||
<br> | <br> | ||
− | <p style="font-size:12px;"><i>See a selection of their amazing drawings <a href="https://static.igem.org/mediawiki/2017/3/30/T--SDU-Denmark--danish-science-festival-drawings.pdf" target="_blank">here</a>.</i></p> | + | <p style="font-size:12px;"><i>See a selection of their amazing drawings <a href="https://static.igem.org/mediawiki/2017/3/30/T--SDU-Denmark--danish-science-festival-drawings.pdf" target="_blank">here</a>.</i></p></div> |
<br class="noContent"> | <br class="noContent"> | ||
Line 612: | Line 421: | ||
<div class="col-xs-12"> | <div class="col-xs-12"> | ||
<h2><span class="highlighted">Our Solution</span></h2><hr> | <h2><span class="highlighted">Our Solution</span></h2><hr> | ||
− | + | ||
+ | <div style="text-align:center;"><p class="raleway P-Larger"><i>“Well, if it can be thought, it can be done, a problem can be overcome”</i></p><br><p class="raleway" style="text-align:center;"><i>E.A. Bucchianeri, Brushstrokes of a Gadfly</i></p></div><br><br class="noContent"> | ||
+ | |||
</div> | </div> | ||
− | + | ||
</div> | </div> | ||
<div class="row"><div class="col-xs-12"> | <div class="row"><div class="col-xs-12"> | ||
<p class="P-Larger"><span class="highlighted"><b>Our Solution</b></span></p> | <p class="P-Larger"><span class="highlighted"><b>Our Solution</b></span></p> | ||
− | <p><span class="highlighted">The bacterial solar battery | + | <p><span class="highlighted">The vision for our bacterial solar battery is to combine two aspects: energy storage and energy conversion, by which we will produce a new and improved type of solar battery. We have named this vision The PowerLeaf</span>. The PowerLeaf consist of two chambers that will be referred to as <i>the outer chamber or energy storing unit</i> and <i>the inner chamber or energy converting unit</i>.</p> |
+ | <ul class="list"> | ||
+ | <li><span class="highlighted">The energy storing unit comprises genetically engineered <i>Escherichia coli</i> (<i>E. coli</i>), which uses solar energy for ATP production to fixate carbon dioxide into the chemically stable polymer cellulose. <span class="highlighted"> The cellulose works as the battery</span> in the PowerLeaf, storing the chemical energy. A light sensing system activates dormancy during nighttime, leading to a reduced loss of energy through metabolism.</span></li> | ||
+ | <li><span class="highlighted">The energy converting unit uses genetically engineered <i>E. coli</i> to consume the stored cellulose by using an inducible switch. Retrieved electrons are transferred by extracellular electron carriers to an anode, resulting in an electrical current.</span></li> | ||
+ | </ul> | ||
+ | <br class="noContent"> | ||
+ | |||
+ | <p><span class="highlighted">The complete system will be combined into a single device containing a compartment for each of the two units</span>. Details about the construction and device will be discussed in the <a href="https://2017.igem.org/Team:SDU-Denmark#integrated-practices" target="_blank">Integrated Practices section</a>. | ||
<br> | <br> | ||
− | <span class="highlighted">The device was originally designed to resemble a plant leaf aimed to provide a nature-in-city ambience</span>. This hypothetical implementation of the PowerLeaf in an urban environment was developed through | + | <span class="highlighted">The device was originally designed to resemble a plant leaf aimed to provide a nature-in-city ambience</span>. This hypothetical implementation of the PowerLeaf in an urban environment was developed through careful consideration, public engagement, and collaborations. We worked with local city planners from our hometown Odense, along with a plastic specialist from SP Moulding, the purpose of which was to advance our pre-established design, as well as attaining other changeable designs. |
<br> | <br> | ||
− | Our vision was clear and ambitions were high, | + | Our vision was clear and ambitions were high. As it turned out though, we had aimed too high, considering the limited timeframe, so at an early stage, <span class="highlighted">we decided to focus on the following features:</span></p> |
+ | |||
<ol class="list"> | <ol class="list"> | ||
<li><span class="highlighted">Light-dependent dormancy system</span></li> | <li><span class="highlighted">Light-dependent dormancy system</span></li> | ||
− | <li><span class="highlighted">Converting CO<sub>2</sub> | + | <li><span class="highlighted">Converting CO<sub>2</sub> into glucose</span></li> |
<li><span class="highlighted">Biosynthesis and secretion of cellulose produced from glucose</span></li> | <li><span class="highlighted">Biosynthesis and secretion of cellulose produced from glucose</span></li> | ||
<li><span class="highlighted">Converting cellulose to glucose</span></li> | <li><span class="highlighted">Converting cellulose to glucose</span></li> | ||
<li><span class="highlighted">Extracellular electron transfer</span></li> | <li><span class="highlighted">Extracellular electron transfer</span></li> | ||
− | </ol> | + | </ol><br> |
− | <br | + | |
− | + | ||
</div></div> | </div></div> | ||
</div> | </div> | ||
Line 645: | Line 462: | ||
<br class="noContent"> | <br class="noContent"> | ||
<p> | <p> | ||
− | It will then be up to | + | It will then be up to future iGEM teams to continue on the development of the PowerLeaf. We would love to see our project become a reality one day, and so we have <span class="highlighted">created a special page <a href="#future-igem-teams" target="_blank">for future iGEM teams</a>, which includes suggestions for a further development of the project</span>. |
</p> | </p> | ||
</div> | </div> | ||
Line 721: | Line 538: | ||
</div> | </div> | ||
<div class="row"> | <div class="row"> | ||
− | <div class="col-xs- | + | <div class="col-xs-5 energy-storing-unit-overview"> |
<object class="highlighted-image project-overview-icon" data="https://static.igem.org/mediawiki/2017/4/41/T--SDU-Denmark--energy-storing-unit-text.svg" type="image/svg+xml" style:"width:100%;"></object><br> | <object class="highlighted-image project-overview-icon" data="https://static.igem.org/mediawiki/2017/4/41/T--SDU-Denmark--energy-storing-unit-text.svg" type="image/svg+xml" style:"width:100%;"></object><br> | ||
<div class="svg-project"><a href="#project-design-dormancy-system"><img class="highlighted-image project-overview-icon" src="https://static.igem.org/mediawiki/2017/1/1f/T--SDU-Denmark--dormancy-system-icon.png" style="width:72%;"></a></div><br> | <div class="svg-project"><a href="#project-design-dormancy-system"><img class="highlighted-image project-overview-icon" src="https://static.igem.org/mediawiki/2017/1/1f/T--SDU-Denmark--dormancy-system-icon.png" style="width:72%;"></a></div><br> | ||
Line 728: | Line 545: | ||
</div> | </div> | ||
− | <div class="col-xs- | + | <div class="col-xs-1"></div> |
+ | |||
+ | <div class="col-xs-5 energy-converting-unit-overview"> | ||
<object class="highlighted-image project-overview-icon" data="https://static.igem.org/mediawiki/2017/9/99/T--SDU-Denmark--energy-converting-unit-text.svg" type="image/svg+xml" style:"width:100%;"></object><br> | <object class="highlighted-image project-overview-icon" data="https://static.igem.org/mediawiki/2017/9/99/T--SDU-Denmark--energy-converting-unit-text.svg" type="image/svg+xml" style:"width:100%;"></object><br> | ||
<div class="svg-project"><a href="#project-design-cellulose-breakdown"><img class="highlighted-image project-overview-icon" src="https://static.igem.org/mediawiki/2017/9/91/T--SDU-Denmark--breakdown-of-cellulose-icon.png" style="width:80%;"></a></div><br> | <div class="svg-project"><a href="#project-design-cellulose-breakdown"><img class="highlighted-image project-overview-icon" src="https://static.igem.org/mediawiki/2017/9/91/T--SDU-Denmark--breakdown-of-cellulose-icon.png" style="width:80%;"></a></div><br> | ||
<div class="svg-project"><a href="#project-design-extracellular-electron-transfer"><img class="highlighted-image project-overview-icon" src="https://static.igem.org/mediawiki/2017/3/30/T--SDU-Denmark--extracellular-electron-transfer-icon.png" style="width:95%;"></a></div><br> | <div class="svg-project"><a href="#project-design-extracellular-electron-transfer"><img class="highlighted-image project-overview-icon" src="https://static.igem.org/mediawiki/2017/3/30/T--SDU-Denmark--extracellular-electron-transfer-icon.png" style="width:95%;"></a></div><br> | ||
</div> | </div> | ||
+ | |||
+ | <div class="col-xs-1"></div> | ||
+ | |||
</div> | </div> | ||
Line 740: | Line 562: | ||
− | <div class="row margin-bottom-75" id="project-design-dormancy-system"><div class="col-xs-12"> | + | <div class="row margin-bottom-75 padding-top-125" id="project-design-dormancy-system" style="margin-top:-125px;"><div class="col-xs-12"> |
<div class"row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/7/7c/T--SDU-Denmark--zzz-icon.svg" type="image/svg+xml"></object><h2>Dormancy System</h2></div></div> | <div class"row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/7/7c/T--SDU-Denmark--zzz-icon.svg" type="image/svg+xml"></object><h2>Dormancy System</h2></div></div> | ||
+ | |||
+ | <div style="text-align:center;"><p><span class="reference-2">Project Overview<span class="referencetext-2"><object data="https://static.igem.org/mediawiki/2017/2/24/T--SDU-Denmark--project-overview-dormancy.svg" style="width:100%;" type="image/svg+xml"></object></span></span></p></div><br> | ||
+ | |||
+ | |||
<p class="P-Larger"><b>Theory</b></p><br> | <p class="P-Larger"><b>Theory</b></p><br> | ||
− | <p>Cyanobacteria contain signal transduction systems, thereby making them capable of <span class="highlighted">sensing and responding to light</span> <span class= | + | |
+ | <p>Cyanobacteria contain signal transduction systems, thereby making them capable of <span class="highlighted">sensing and responding to light</span><span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3732953/">Bussell AN, Kehoe DM. Control of a four-color sensing photoreceptor by a two-color sensing photoreceptor reveals complex light regulation in cyanobacteria. Proceedings of the National Academy of Sciences of the United States of America. 2013;110(31):12834-9.</a></span></span>. This ability gives the organisms the opportunity, to <span class="highlighted">adapt and optimize their metabolism to a circadian rhythm</span>. Photoreceptors in the plasma membrane, of which phytochromes are especially abundant and well described, are responsible for this property<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/11145881">Vierstra RD, Davis SJ. Bacteriophytochromes: new tools for understanding phytochrome signal transduction. Seminars in cell & developmental biology. 2000;11(6):511-21.</a></span></span>. In 2004, the <a href="https://2004.igem.org/austin.cgi" target="_blank">UT Austin iGEM team</a> made a light response system consisting of a photoreceptor combined with an intracellular indigenous regulator system<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/16306980">Levskaya A, Chevalier AA, Tabor JJ, Simpson ZB, Lavery LA, Levy M, et al. Synthetic biology: engineering Escherichia coli to see light. Nature. 2005;438(7067):441-2.</a></span></span>. EnvZ and OmpR makes up the two-component system naturally found in <i>E. coli</i>. The photoreceptor known as Cph1 was isolated from the cyanobacteria <i>Synechocytis</i> PCC6803. Cph1 has functional combination sites, which combined with the kinase EnvZ forms a two-domain receptor, known as Cph8. Activation of Cph8 is mediated by the chromophore phycocyanobilin, PCB that is <span class="highlighted">sensitive to red light</span> with maximal absorbance at 662 nm<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/11532008">Lamparter T, Esteban B, Hughes J. Phytochrome Cph1 from the cyanobacterium Synechocystis PCC6803. Purification, assembly, and quaternary structure. European journal of biochemistry. 2001;268(17):4720-30.</a></span></span>. | ||
<br> | <br> | ||
<span class="highlighted">When not exposed to light</span>, PCB activates the phytochrome Cph1, thereby promoting kinase activity through the EnvZ kinase. When the transcription factor OmpR is phosphorylated by EnvZ, <span class="highlighted">expression of genes regulated by the OmpR-regulated promoter is initiated. Excitation of PCB by red light</span> results in a situation where the transcription factor OmpR is not regulated. The absence of phosphorylated OmpR leads to no activation of the OmpR-regulated promoter, thereby <span class="highlighted">preventing gene expression</span>. | <span class="highlighted">When not exposed to light</span>, PCB activates the phytochrome Cph1, thereby promoting kinase activity through the EnvZ kinase. When the transcription factor OmpR is phosphorylated by EnvZ, <span class="highlighted">expression of genes regulated by the OmpR-regulated promoter is initiated. Excitation of PCB by red light</span> results in a situation where the transcription factor OmpR is not regulated. The absence of phosphorylated OmpR leads to no activation of the OmpR-regulated promoter, thereby <span class="highlighted">preventing gene expression</span>. | ||
Line 753: | Line 580: | ||
<br><p> | <br><p> | ||
− | Using the <span class="highlighted">photocontrol device to control a toxin-antitoxin system</span> is a system composed of two gene products, of which one specifies a cell toxin and the other an antitoxin, which neutralizes the toxic effect caused by the toxin. In <i>E. coli</i> K-12 the cytotoxin RelE and antitoxin RelB comprise such a system <span class= | + | Using the <span class="highlighted">photocontrol device to control a toxin-antitoxin system</span> is a system composed of two gene products, of which one specifies a cell toxin and the other an antitoxin, which neutralizes the toxic effect caused by the toxin. In <i>E. coli</i> K-12 the cytotoxin RelE and antitoxin RelB comprise such a system<span class=”reference”><span class="referencetext"><a target="blank" href=" https://www.ncbi.nlm.nih.gov/pubmed/9767574">Gotfredsen M, Gerdes K. The Escherichia coli relBE genes belong to a new toxin-antitoxin gene family. Molecular microbiology. 1998;29(4):1065-76.</a></span></span>. Expression of the <span class="highlighted">cytotoxin RelE inhibits translation in the cells</span>, due to its ability to cleave mRNA found in the A-site of the ribosome. <span class="highlighted">RelB neutralizes the toxic effect of RelE</span> through interaction between the two proteins. Whether the cell lie dormant in response to expression of RelE depends on the ratio of antitoxin RelB and RelE present in the cell. Several studies have shown that RelB and RelE form a complex with RelB:RelE stoichiometry of 2:1<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/19747491">Overgaard M, Borch J, Gerdes K. RelB and RelE of Escherichia coli form a tight complex that represses transcription via the ribbon-helix-helix motif in RelB. Journal of molecular biology. 2009;394(2):183-96.</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard M, Borch J, Jorgensen MG, Gerdes K. Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular microbiology. 2008;69(4):841-57.</a></span></span>. When the RelB:RelE stoichiometric-ratio is lowered to 1:1, studies show that RelB is not able to protect the cells against the RelE-caused translational inhibition<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard M, Borch J, Jorgensen MG, Gerdes K. Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular microbiology. 2008;69(4):841-57.</a></span></span>. For further information about the theory behind the light-dependent dormancy system, <span class="btn-link btn-lg" data-toggle="modal" data-target="#light-sensing-system-theory">read here</span>. |
</p><br> | </p><br> | ||
Line 778: | Line 605: | ||
<b>The Photocontrol Device Mediates Light-Dependent Gene Expression</b><br> | <b>The Photocontrol Device Mediates Light-Dependent Gene Expression</b><br> | ||
− | Plants and several photosynthetic microorganisms, such as cyanobacteria, contain signal transduction systems, which makes them capable of reacting to light <span class= | + | Plants and several photosynthetic microorganisms, such as cyanobacteria, contain signal transduction systems, which makes them capable of reacting to light<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3732953/">Bussell AN, Kehoe DM. Control of a four-color sensing photoreceptor by a two-color sensing photoreceptor reveals complex light regulation in cyanobacteria. Proceedings of the National Academy of Sciences of the United States of America. 2013;110(31):12834-9.</a></span></span>. This ability gives the organisms the opportunity to adapt and optimise the regulation of their metabolic rate in response to sunlight. This property is achieved by photoreceptors incorporated in their plasma membrane, of which phytochromes are the most abundant and well described<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/11145881">Vierstra RD, Davis SJ. Bacteriophytochromes: new tools for understanding phytochrome signal transduction. Seminars in cell & developmental biology. 2000;11(6):511-21.</a></span></span>.<br> |
− | Several two-component signal transduction systems evolved in <i>E. coli</i> enables it to respond to various external conditions, such as osmotic stress, lack of metabolites and other external stress factors. Nothing indicates that light initiates such a two-component signal transduction pathway in wild type <i>E. coli</i> <span class= | + | Several two-component signal transduction systems evolved in <i>E. coli</i> enables it to respond to various external conditions, such as osmotic stress, lack of metabolites and other external stress factors. Nothing indicates that light initiates such a two-component signal transduction pathway in wild type <i>E. coli</i><span class=”reference”><span class="referencetext"><a target="blank" href="http://www.microbiologyresearch.org/docserver/fulltext/micro/22/1/mic-22-1-113.pdf?expires=1507966841&id=id&accname=guest&checksum=574A5913441399B962AA6A4F887C733E">Alper T, Gillies NE. The relationship between growth and survival after irradiation of Escherichia coli strain B and two resistant mutants. Journal of general microbiology. 1960;22:113-28.</a></span></span>. The <a href="https://2004.igem.org/austin.cgi" target="_blank">UT Austin iGEM 2004 team</a> applied the light sensing property of phototrophs to an <i>E. coli</i>. By aligning different phytochromes with the intrinsic kinase EnvZ from <i>E. coli</i> they revealed a way to create a two-component system consisting of a photoreceptor with an intracellular indigenous regulator system found in <i>E. coli</i>. By establishing this system the bacteria acquired the ability to respond to red light<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/16306980">Levskaya A, Chevalier AA, Tabor JJ, Simpson ZB, Lavery LA, Levy M, et al. Synthetic biology: engineering Escherichia coli to see light. Nature. 2005;438(7067):441-2.</a></span></span>. The photoreceptor from phytochrome known as Cph1 was isolated from the cyanobacteria <i>Synechocytis</i> PCC6803. Cph1 has a fusion site, which can be used to combine it with the kinase EnvZ, from the EnvZ-OmpR kinase-regulator system, to form a two-domain receptor known as Cph8. The chromophore phycocyanobilin (PCB) absorbs light in the red region with maximal absorbance at 662 nm<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/11532008">Lamparter T, Esteban B, Hughes J. Phytochrome Cph1 from the cyanobacterium Synechocystis PCC6803. Purification, assembly, and quaternary structure. European journal of biochemistry. 2001;268(17):4720-30.</a></span></span>. When heterogeneously expressed in <i>E. coli</i>, it can, in combination with the light receptor Cph8, be used to form a light-sensitive circuit, making <i>E. coli</i> able to respond to red light<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3053042/">abor JJ, Levskaya A, Voigt CA. Multichromatic control of gene expression in Escherichia coli. Journal of molecular biology. 2011;405(2):315-324. </a></span></span>. |
<br> | <br> | ||
In situations where no red light is present, the photoreceptor PCB activates the phytochrome Cph1, thereby promoting kinase activity through the EnvZ kinase, illustrated in figure #. When the transcription factor OmpR is phosphorylated by EnvZ, expression of genes controlled by the OmpR-regulated promoter is initiated. Excitation of the PCB by red light, results in a situation, where EnvZ will not be able to phosphorylate the transcription factor OmpR. The lack of phosphorylated OmpR leads to no activation of the OmpR-regulated promoter, thereby preventing gene expression by this promoter.<br> | In situations where no red light is present, the photoreceptor PCB activates the phytochrome Cph1, thereby promoting kinase activity through the EnvZ kinase, illustrated in figure #. When the transcription factor OmpR is phosphorylated by EnvZ, expression of genes controlled by the OmpR-regulated promoter is initiated. Excitation of the PCB by red light, results in a situation, where EnvZ will not be able to phosphorylate the transcription factor OmpR. The lack of phosphorylated OmpR leads to no activation of the OmpR-regulated promoter, thereby preventing gene expression by this promoter.<br> | ||
Line 788: | Line 615: | ||
<b>RelE and RelB Comprise a Toxin-Antitoxin System in <i>E. coli</i></b><br> | <b>RelE and RelB Comprise a Toxin-Antitoxin System in <i>E. coli</i></b><br> | ||
− | A toxin-antitoxin system is a system composed of two gene products, of which one specifies a cell toxin and the other an antitoxin, which neutralizes the toxic effect caused by the toxin. In <i>E. coli</i> K-12 the cytotoxin RelE and antitoxin RelB comprise such a system <span class= | + | A toxin-antitoxin system is a system composed of two gene products, of which one specifies a cell toxin and the other an antitoxin, which neutralizes the toxic effect caused by the toxin. In <i>E. coli</i> K-12 the cytotoxin RelE and antitoxin RelB comprise such a system<span class=”reference”><span class="referencetext"><a target="blank" href=" https://www.ncbi.nlm.nih.gov/pubmed/9767574">Gotfredsen M, Gerdes K. The Escherichia coli relBE genes belong to a new toxin-antitoxin gene family. Molecular microbiology. 1998;29(4):1065-76.</a></span></span>. Expression of the cytotoxin RelE inhibits translation in the cells, due to its ability to cleave mRNA found in the A-site of the ribosome<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/12526800">Pedersen K, Zavialov AV, Pavlov MY, Elf J, Gerdes K, Ehrenberg M. The bacterial toxin RelE displays codon-specific cleavage of mRNAs in the ribosomal A site. Cell. 2003;112(1):131-40.</a></span></span>. RelB neutralize the toxic effect of RelE through interaction between the two proteins. In situations of amino acid starvation, it is appropriate for the bacteria to halt the translation in order to avoid errors owing to absent amino acids. Consequently, one of the exciting factors for the expression of RelE is conditioned by amino acid starvation<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/12526800">Pedersen K, Zavialov AV, Pavlov MY, Elf J, Gerdes K, Ehrenberg M. The bacterial toxin RelE displays codon-specific cleavage of mRNAs in the ribosomal A site. Cell. 2003;112(1):131-40.</a></span></span>. |
<br> | <br> | ||
− | Whether the cell lie dormant in response to expression of RelE depends on the ratio of RelB and RelE present in the cell. Several studies have shown that RelB RelE form a complex with RelB:RelE stoichiometry of 2:1 <span class= | + | Whether the cell lie dormant in response to expression of RelE depends on the ratio of RelB and RelE present in the cell. Several studies have shown that RelB RelE form a complex with RelB:RelE stoichiometry of 2:1<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/19747491">Overgaard M, Borch J, Gerdes K. RelB and RelE of Escherichia coli form a tight complex that represses transcription via the ribbon-helix-helix motif in RelB. Journal of molecular biology. 2009;394(2):183-96.</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard M, Borch J, Jorgensen MG, Gerdes K. Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular microbiology. 2008;69(4):841-57.</a></span></span>, When the RelB:RelE stoichiometric-ratio is lowered to 1:1, studies show that RelB is not able to protect the cells against the RelE-caused translational inhibition<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard M, Borch J, Jorgensen MG, Gerdes K. Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular microbiology. 2008;69(4):841-57.</a></span></span>. To prevent free RelE circulating and discharging toxic effects in the cells under favorable conditions, studies in vivo have shown that RelB is present in 10x higher concentrations than RelE<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/19747491">Overgaard M, Borch J, Gerdes K. RelB and RelE of Escherichia coli form a tight complex that represses transcription via the ribbon-helix-helix motif in RelB. Journal of molecular biology. 2009;394(2):183-96.</a></span></span>. The heterologous induction of RelE could cause dissonance in the RelB:RelE ratio leading to serious consequences for the cells<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/11717402">Christensen SK, Mikkelsen M, Pedersen K, Gerdes K. RelE, a global inhibitor of translation, is activated during nutritional stress. Proceedings of the National Academy of Sciences of the United States of America. 2001;98(25):14328-33.</a></span></span>. The bacteria are not killed when RelE is present in abundance, but high expression of the RelE gene makes awakening of the bacterial cells a challenge<span class=”reference”><span class="referencetext"><a target="blank" href=" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3294780/">Tashiro Y, Kawata K, Taniuchi A, Kakinuma K, May T, Okabe S. RelE-Mediated Dormancy Is Enhanced at High Cell Density in Escherichia coli. J Bacteriol. 2012;194(5):1169-76.</a></span></span>. Hence, introducing a toxin to cells in a successful manner constitutes a challenge. |
</p> | </p> | ||
Line 818: | Line 645: | ||
<div id="modelling"> | <div id="modelling"> | ||
<p class="P-Larger"><b>Modelling</b></p><br> | <p class="P-Larger"><b>Modelling</b></p><br> | ||
+ | |||
+ | <div class="row"><div class="col-xs-12"><div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/9/91/T--SDU-Denmark--modelling-figure-1-rele-relb.svg" type="image/svg+xml" style="width:50%;"></object></div></div></div> | ||
+ | <br> | ||
+ | |||
<p> | <p> | ||
<b>Modelling of the RelE-RelB System is Essential to Avoid Irrevocable Dormancy</b><br> | <b>Modelling of the RelE-RelB System is Essential to Avoid Irrevocable Dormancy</b><br> | ||
− | Controllable dormancy is a feature that holds the potential to be applied in many different situations. | + | <p>Controllable dormancy is a feature that holds the potential to be applied in many different situations. However, inducing dormancy and bringing the bacteria back to a metabolic active state is like balancing on a tightrope, and to establish the basis of future implementations, the properties of this system would have to be investigated further. In an endeavour to provide this basic knowledge, <span class="highlighted">stochastic modelling utilising the <span class="btn-link btn-lg" data-toggle="modal" data-target="#gillespie-algorithm"> Gillespie algorithm </span> was performed in an attempt to prognosticate the system</span> and simulate the interactions between the toxin and antitoxin. |
− | <br> | + | <span class="highlighted">The toxin RelE is inhibited by the antitoxin RelB through complex formation</span>, and both proteins interact with their promoter in a feedback mechanism. |
+ | To consolidate the model, the capacity of the toxin-antitoxin system was assessed in an experiment, as the controllability of the dormancy system was studied through manual regulation of RelE and RelB expression.<br> | ||
+ | You can read more about the modelling <span class="btn-link btn-lg" data-toggle="modal" data-target="#toxin-antitoxin-system">here</span>. </p> | ||
+ | <br></p> | ||
− | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/ | + | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/f/f6/T--SDU-Denmark--model-kort-graph.svg" type="image/svg+xml" style="width:100%;"></object></div> |
+ | <br><div class="figure-text"><p><b>Figure #.</b> Left: The time required for the bacteria to enter dormancy varies with the expression level of RelB. | ||
+ | Right: Only one of the tested configurations, RelB<sub>2</sub>:50-RelE:35, causes the bacteria to regain their activity within the modelled time. The data is based on the simulation of 1000 independent bacteria.</p></div><br class="noContent"> | ||
− | + | <p> | |
− | <p> | + | The simulated data revealed, that when enhanced RelE production is implemented in order to induce dormancy in <i>E. coli</i>, the effect come easily. However, <span class="highlighted"> implementation of RelB expression is also found necessary</span> to ensure that the bacteria are able to enter an active state again. <br> |
− | The model showed that the system is sensitive to the RelE:RelB ratio as well as the total | + | The model showed that <span class="highlighted">the system is sensitive to the RelE:RelB ratio</span> as well as the total amount of produced toxin. As seen in figure #, implementation with production rates in the vicinity of <span class="highlighted">50 and 35 molecules per minute for RelB and RelE respectively was found to be suitable for balancing our system</span>; the bacteria lay dormant within the computed time and re-enter an active state within minutes. <br> |
− | </ | + | |
+ | The simulated data made it evident, that <span class="highlighted">implementing an optimised dormancy system comprises a challenge</span>, as the individual expression levels of RelE and RelB, as well as their interaction, has a crucial impact on the regulation of dormancy. Thus, controlled gene expression of both RelE and RelB is required to implement a controllable dormancy system in the PowerLeaf. If you want to dig deeper into this crucial part of our system, read the full results <span class="btn-link btn-lg" data-toggle="modal" data-target="#model-results">here</span>. </p> | ||
</div> | </div> | ||
Line 845: | Line 682: | ||
<div class="col-md-1"></div> | <div class="col-md-1"></div> | ||
<div class="col-md-10"> | <div class="col-md-10"> | ||
− | |||
<p> | <p> | ||
The Gillespie algorithm is a way to calculate the evolution of stochastic functions; in this case cell concentrations. To use the algorithm, two things are required:</p> | The Gillespie algorithm is a way to calculate the evolution of stochastic functions; in this case cell concentrations. To use the algorithm, two things are required:</p> | ||
<ol class="list"> | <ol class="list"> | ||
− | <li> | + | <li>Reaction rates of the system at a given configuration.</li> |
− | <li> | + | <li>A random number generator.</li> |
</ol> | </ol> | ||
− | <p>For each time step two things are calculated | + | <p> |
− | The time before next step is given by< | + | For each time step, two things are calculated using the random number generator: </p> |
− | Δt=S<sup>-1</sup>log( | + | <ol class="list"> |
+ | <li>The time before next reaction.</li> | ||
+ | <li>Which reaction occurs.</li> | ||
+ | </ol> | ||
+ | <p> | ||
+ | The time before next step is given by: | ||
+ | </p> | ||
+ | <div style="text-align:center;"><p>Δt=S<sup>-1</sup>log(r<sub>1</sub><sup>-1</sup>)</p></div><br> | ||
+ | <p> | ||
+ | Where S is the sum of the reaction rates and r<sub>1</sub> is a random number between 0 and 1. This gives the time, as if the system was one reaction with reaction rate S, using the random number to give an exponential distribution. | ||
<br> | <br> | ||
− | + | The reaction is chosen proportionally to each individual reaction rate using another random number, where reactions with high rates will occur most frequently. | |
<br> | <br> | ||
− | + | As each reaction is carried out, the new time is the sum of the previous and added reaction times. | |
− | + | ||
− | + | These calculations are carried out until the time reaches the wanted limit, or a specific number of reactions has occurred. It is necessary to have a limit on the number of reactions, as it elsewise is possible for the calculations to continue indefinitely. | |
+ | |||
</p> | </p> | ||
Line 885: | Line 731: | ||
<div class="modal-header"> | <div class="modal-header"> | ||
<button type="button" class="close" data-dismiss="modal">×</button> | <button type="button" class="close" data-dismiss="modal">×</button> | ||
− | <h2 class="modal-title"> | + | <h2 class="modal-title">Stochastic Modelling of the RelE-RelB Dormancy System</h2> |
</div> | </div> | ||
<div class="modal-body" margin-right="10%"> | <div class="modal-body" margin-right="10%"> | ||
Line 891: | Line 737: | ||
<div class="col-md-1"></div> | <div class="col-md-1"></div> | ||
<div class="col-md-10"> | <div class="col-md-10"> | ||
− | <p class="P-Larger"><b> | + | <p class="P-Larger"><b>RelE and RelB Regulate Dormancy and Influence Their Own Expression</b><br> |
<p> | <p> | ||
− | + | Modelling of the effects of different RelE and RelB expression levels were performed as an important aspect in the implementation of the RelE-RelB toxin-antitoxin system. The toxin RelE constrains bacterial growth by mRNA degradation, thereby inhibiting translation, whereas the antitoxin RelB inhibits this toxic effect by forming complexes with RelE. As seen in figure #a, three different protein complexes are formed, namely RelB<sub>2</sub>, RelB<sub>2</sub>RelE, and RelB<sub>2</sub>RelE<sub>2</sub>, containing zero, one, and two RelE molecules respectively<span class=”reference”><span class="referencetext"><a target="blank" href="https://doi.org/10.1016/j.jmb.2008.04.039.">Guang-Yao Li, Yonglong Zhang, Masayori Inouye, Mitsuhiko Ikura, Structural Mechanism of Transcriptional Autorepression of the Escherichia coli RelB/RelE Antitoxin/Toxin Module, In Journal of Molecular Biology, Volume 380, Issue 1, 2008, Pages 107-119, ISSN 0022-2836</a></span></span>. | |
− | < | + | |
− | + | ||
− | + | ||
− | + | ||
</p><br> | </p><br> | ||
<object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/9/91/T--SDU-Denmark--modelling-figure-1-rele-relb.svg" type="image/svg+xml" style="width:100%;"></object> | <object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/9/91/T--SDU-Denmark--modelling-figure-1-rele-relb.svg" type="image/svg+xml" style="width:100%;"></object> | ||
+ | <br><div class="figure-text"><p><b>Figure #.</b> The three toxin-antitoxin complexes RelB<sub>2</sub>, RelB<sub>2</sub>RelE, and RelB<sub>2</sub>RelE<sub>2</sub>.</p></div><br class="noContent"> | ||
− | <p> | + | <p>The expression of both RelE and RelB is regulated by the <i>relBE</i> promoter, which is influenced differently by each of the complexes, as seen in figure #b. When small amounts of RelE is present, RelB<sub>2</sub> and RelB<sub>2</sub>RelE repress transcription through <i>relBE</i> by binding to the operator sequence. However, when high amounts of RelE are present, the toxin mitigates this repression by reacting with complexes bound to the operator sequence<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span>. |
− | + | </p> | |
− | Two different models were used with two different approaches | + | <object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/6/61/T--SDU-Denmark--modelling-figure-2-rele-relb.svg" type="image/svg+xml" style="width:100%;"></object> |
+ | <br><div class="figure-text"><p><b>Figure #.</b> The interactions between the toxin-antitoxin complexes and the relBE promoter controlling the expression of RelE and RelB. RelE mediates the degradation of mRNA, thereby inhibiting translation.</p></div><br class="noContent"> | ||
+ | |||
+ | <p>During starvation, the half-life of RelB decreases significantly due to a Lon-protease<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard, M., Borch, J., Jørgensen, M. G. and Gerdes, K. (2008), Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular Microbiology, 69: 841–857. doi:10.1111/j.1365-2958.2008.06313.x</a></span></span>, causing a shift in the equilibrium of RelB and RelE to a higher level of RelE. In a non-starvation situation, the interactions with the operator sequence keeps the amount of free RelE at a low level, thereby stabilising the system<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span>. In our simulation, the shift in equilibrium is made by introducing additional expression of RelE. <br> | ||
+ | Two different models were used with two different approaches: | ||
+ | </p> | ||
+ | |||
+ | <ol class="list"> | ||
+ | <li>How a given configuration of RelB and RelE production increases the RelE concentration and whether it could induce dormancy within 2 hours.</li> | ||
+ | <li>The time required for the bacteria to exit dormancy for each of the configurations, that is, how long it takes the levels of free RelE to decrease again. </li> | ||
+ | </ol><br> | ||
+ | <br class="noContent"> | ||
<p class="P-Larger"><b>Rates and Reactions</b></p><br> | <p class="P-Larger"><b>Rates and Reactions</b></p><br> | ||
− | <p>The skeleton of | + | <p>The skeleton of toxin-antitoxin system inherent to <i>E. coli</i> in the model was based on the study by Cataudella et al. 2012<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span>. In an <i>E. coli</i> cell with a size of 1-2 μm, each nM of concentration can be approximated to 1 molecule. Thus all units are converted to molecules<sup>-1</sup>, as this fits the premises of the Gillespie algorithm. To simplify the model, the high affinity of RelE and RelB was used to ignore single RelB and only consider the dimer, RelB<sub>2</sub><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="http://www.uniprot.org/uniprot/P0C079">UniProtKB - P0C079 (RELB_ECOLI)</a></span></span>. Thus, all mentions of RelB in the model refers to its dimer. |
<br> | <br> | ||
− | + | Whilst RelB has a relatively low half-life at about 3-5 minutes<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard, M., Borch, J., Jørgensen, M. G. and Gerdes, K. (2008), Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular Microbiology, 69: 841–857. doi:10.1111/j.1365-2958.2008.06313.x</a></span></span>, RelE is rather stable and its half-life, here set to 43 min, is primarily an effect from dilution caused by the bacterial growth<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span>. However, when growth is restricted during dormancy, the half-life of RelE is increased to 2000 min, corresponding to approximately one day, as the dilution effect is no longer applicable. As the protein complexes are relatively stable, their half-life was set to the same as RelE. However, for RelE to become active in the inherent system under starvation, RelB in complexes must decay<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span>, for which reason the rate was set to a fourth of free RelB. | |
+ | |||
<br> | <br> | ||
− | + | The transcription rates of RelE and RelB are based on the concentration of RelE and RelB under stable conditions where RelB is ten times more prevalent than RelE<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812701/">Overgaard M., Borch J., Gerdes K. RelB and RelE of Escherichia coli form a tight complex that represses transcription via the ribbon-helix-helix motif in RelB. J. Mol. Biol. 2009;394:183–196. doi: 10.1016/j.jmb.2009.09.006</a></span></span>. Consequently, RelB has been given a transcription rate 100 times higher than RelE to make up for the higher half-life of RelE. | |
<br> | <br> | ||
− | + | For the full set of reactions, <a href="https://static.igem.org/mediawiki/2017/1/1a/T--SDU-Denmark--Equations-for-model.pdf" target="_blank">read here</a> | |
− | + | ||
<br> | <br> | ||
− | + | Each bacterial chromosome has two operators, each of which can bind one RelB<sub>2</sub> dimer (O(RelB<sub>2</sub>)) or either one or two RelB<sub>2</sub>RelE complexes (O(RelB<sub>2</sub>RelE) and O(RelB<sub>2</sub>RelE)<sub>2</sub>)<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard, M., Borch, J., Jørgensen, M. G. and Gerdes, K. (2008), Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular Microbiology, 69: 841–857. doi:10.1111/j.1365-2958.2008.06313.x</a></span></span>. | |
− | </ | + | Each cell is assumed to have four chromosomes with one relBE promoter each, as this is an average number of chromosomes for an exponentially growing <i>E. coli</i> cell<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard, M., Borch, J., Jørgensen, M. G. and Gerdes, K. (2008), Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular Microbiology, 69: 841–857. doi:10.1111/j.1365-2958.2008.06313.x</a></span></span>. This was found to stabilise the inherent system considerably compared to a system containing one chromosome per cell, as the systems exhibited similar behaviour but with different amounts of noise<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard, M., Borch, J., Jørgensen, M. G. and Gerdes, K. (2008), Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular Microbiology, 69: 841–857. doi:10.1111/j.1365-2958.2008.06313.x</a></span></span>. |
− | + | The initial values in the model are listed below. | |
− | + | </p> | |
− | + | <table class="table"> | |
− | + | ||
− | The initial values in the model | + | |
− | </p | + | |
− | + | ||
− | <table> | + | |
<tr> | <tr> | ||
<th> Molecule </th> | <th> Molecule </th> | ||
Line 934: | Line 783: | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
− | <td> | + | <td> mRNA </td> |
<td> 7 </td> | <td> 7 </td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
− | <td> RelB </td> | + | <td> RelB<sub>2</sub> </td> |
<td> 410 </td> | <td> 410 </td> | ||
</tr> | </tr> | ||
Line 946: | Line 795: | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
− | <td> | + | <td> RelB<sub>2</sub>RelE </td> |
<td> 65 </td> | <td> 65 </td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
− | <td> | + | <td> RelB<sub>2</sub>RelE<sub>2</sub> </td> |
<td> 11 </td> | <td> 11 </td> | ||
</tr> | </tr> | ||
Line 958: | Line 807: | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
− | <td> O(RelB) </td> | + | <td> O(RelB<sub>2</sub>) </td> |
<td> 2 </td> | <td> 2 </td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
− | <td> O( | + | <td> O(RelB<sub>2</sub>RelE) </td> |
<td> 0 </td> | <td> 0 </td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
− | <td> O( | + | <td> O(RelB<sub>2</sub>RelE)<sub>2</sub> </td> |
<td> 2 </td> | <td> 2 </td> | ||
</tr> | </tr> | ||
</table> | </table> | ||
− | |||
− | |||
<br> | <br> | ||
− | + | <p>All values are integers as the Gillespie algorithm works with discrete numbers of molecules. The values were chosen based on a stable equilibrium found by letting the model run a simulation of the inherent system over 450 minutes with different starting values. | |
− | <p> | + | |
<br> | <br> | ||
− | + | Ranging from 1-350 molecules per minute, the implemented expression rates of RelE and RelB in the model might seem too high, as the rates in the inherit system is effectively around 80-100 for RelB and 2-5 for RelE. However, the possibility of placing the <i>relE</i> and <i>relB</i> genes under regulation of controllable promoters makes the high total production values reasonable. | |
<br> | <br> | ||
− | + | When the inherent toxin-antitoxin system is activated under starvation, 40-70 molecules of free RelE are found in each cell, making it reasonable to believe that the cells enter dormancy when a few tens of free RelE copies are present. This result obtained from the model is in agreement with literature<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span> | |
<br> | <br> | ||
− | For | + | For the full list of constants, see the attached Table 1 at the bottom of this page. |
</p><br> | </p><br> | ||
− | |||
<br class="noContent"> | <br class="noContent"> | ||
− | <p class="P-Larger"><b>Running the Model</b></p> | + | <p class="P-Larger"><b>Running the Model</b></p><br> |
− | <p> | + | <p>To give a stochastic view of the system, the Gillespie algorithm was run in the computer programming language MATLAB, utilising an <a href="https://se.mathworks.com/matlabcentral/fileexchange/34707-gillespie-stochastic-simulation-algorithm" target="_blank">implementation</a> made by MATLAB user Nezar. |
<br> | <br> | ||
− | For the | + | For the runs simulating dormancy, deterministic initial values were used and the system was run for 30 minutes without activation of the inserted toxin promoter. This resulted in a stochastic distribution of initial values mimicking variations between cells. Analysis showed, that 30 minutes was enough for the model to find a stable distribution, which is realistic considering the growth cycle of an <i>E. coli</i> cell. |
<br> | <br> | ||
− | For | + | For the runs simulating activation, the data generated at the end of a dormancy run was used as initial value and deactivated expression of RelE. When the concentration of free RelE decreases to below 15 copies, a cell is considered active. This value was probably set too low, but tests displayed marginal difference between 15 and 45 copies, where the lower limit was chosen to decrease uncertainty of the cell state. |
<br> | <br> | ||
− | All runs | + | All runs simulated 1000 cells, which should be sufficient to get stable averages and the model assumed well-mixed conditions in every cell and considered each cell independently. Furthermore, the model has no cut-off for maximum values of RelE, as the exact relation between RelE concentration and dormancy state is unknown, yet a functional cut-off was found through activation times. |
+ | <br> | ||
+ | <a href="https://static.igem.org/mediawiki/2017/1/1e/Matlab-scripts_SDU.zip" target="_blank">Download of Matlab-scripts</a></p><br> | ||
+ | <br class="noContent"> | ||
+ | <br class="noContent"> | ||
− | </p> | + | <p class="P-Larger"><b>Table 1</b></p><br> |
+ | <table class="table"> | ||
+ | <tr> | ||
+ | <th>Constant</th> | ||
+ | <th>Identifier</th> | ||
+ | <th>Units</th> | ||
+ | <th>Value</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>mRNA transcription rate<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td>α<sub>0</sub></th> | ||
+ | <td>1/min</th> | ||
+ | <td>154.665</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>mRNA half-life<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td>τ<sub>m</sub></th> | ||
+ | <td>min</th> | ||
+ | <td>7.2</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>RelB half-life<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812701/">Overgaard M., Borch J., Gerdes K. RelB and RelE of Escherichia coli form a tight complex that represses transcription via the ribbon-helix-helix motif in RelB. J. Mol. Biol. 2009;394:183–196. doi: 10.1016/j.jmb.2009.09.006</a></span></span></th> | ||
+ | <td>τ<sub>B</sub></th> | ||
+ | <td>min</th> | ||
+ | <td>4.3</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>RelE half-life<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td>τ<sub>E</sub></th> | ||
+ | <td>min</th> | ||
+ | <td>43 (growing)<br> 2000 (dormant)</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Bound RelB half-life<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812701/">Overgaard M., Borch J., Gerdes K. RelB and RelE of Escherichia coli form a tight complex that represses transcription via the ribbon-helix-helix motif in RelB. J. Mol. Biol. 2009;394:183–196. doi: 10.1016/j.jmb.2009.09.006</a></span></span></th> | ||
+ | <td>τ<sub>c</sub></th> | ||
+ | <td>min</th> | ||
+ | <td>17</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>RelB transcription rate<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td><i>trans</i><sub>B</sub></th> | ||
+ | <td>1/min</th> | ||
+ | <td>15</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>RelE transcription rate<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td><i>trans</i><sub>E</sub></th> | ||
+ | <td>1/min</th> | ||
+ | <td>0.3</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Binding rate<span class="reference"><span class="referencetext">Sneppen K, Zocchi G. Physics in Molecular Biology. Cambridge, UK: Cambridge University Press; 2005.</span></span></th> | ||
+ | <td>k <sub>b</sub></th> | ||
+ | <td>1/min</th> | ||
+ | <td>3.8</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Dissociation rate B<sub>2</sub>E<span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard, M., Borch, J., Jørgensen, M. G. and Gerdes, K. (2008), Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular Microbiology, 69: 841–857. doi:10.1111/j.1365-2958.2008.06313.x</a></span></span></th> | ||
+ | <td>K<sub>D</sub> (B<sub>2</sub>E)</th> | ||
+ | <td>molecules</th> | ||
+ | <td>0.3</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Dissociation rate B<sub>2</sub>E<sub>2</sub><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18532983">Overgaard, M., Borch, J., Jørgensen, M. G. and Gerdes, K. (2008), Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Molecular Microbiology, 69: 841–857. doi:10.1111/j.1365-2958.2008.06313.x</a></span></span></th> | ||
+ | <td> K<sub>D</sub>(B<sub>2</sub>E<sub>2</sub>)</th> | ||
+ | <td>molecules</th> | ||
+ | <td>0.3</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Dissociation rate O.B<sub>f</sub><span class="reference"><span class="referencetext"><a target="blank" href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2958.1998.00993.x/abstract">Gotfredsen, M. and Gerdes, K. (1998), The Escherichia coli relBE genes belong to a new toxin–antitoxin gene family. Molecular Microbiology, 29: 1065–1076. doi:10.1046/j.1365-2958.1998.00993.x</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td>K<sub>D1</sub></th> | ||
+ | <td>molecules</th> | ||
+ | <td>10</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Dissociation rate O.B<sub>2</sub>E<span class="reference"><span class="referencetext"><a target="blank" href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2958.1998.00993.x/abstract">Gotfredsen, M. and Gerdes, K. (1998), The Escherichia coli relBE genes belong to a new toxin–antitoxin gene family. Molecular Microbiology, 29: 1065–1076. doi:10.1046/j.1365-2958.1998.00993.x</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td> K<sub>D2</sub></th> | ||
+ | <td>molecules</th> | ||
+ | <td>0.04</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Dissociation rate O.(B<sub>2</sub>E)<sub>2</sub><span class="reference"><span class="referencetext"><a target="blank" href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2958.1998.00993.x/abstract">Gotfredsen, M. and Gerdes, K. (1998), The Escherichia coli relBE genes belong to a new toxin–antitoxin gene family. Molecular Microbiology, 29: 1065–1076. doi:10.1046/j.1365-2958.1998.00993.x</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td> K<sub>D3</sub></th> | ||
+ | <td>molecules</th> | ||
+ | <td>30</th> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Cleavage rate<span class="reference"><span class="referencetext"><a target="blank" href="http://www.sciencedirect.com/science/article/pii/S0092867402012485?">Pedersen K, et al. The bacterial toxin RelE displays codon-specific cleavage of mRNAs in the ribosomal A site. Cell. 2003;112:131–140. doi: 10.1016/S0092-8674(02)01248-5</a></span></span> | ||
+ | <span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3413109/">Cataudella I., Trusina A., Sneppen K., Gerdes K., Mitarai N. Conditional cooperativity in toxin-antitoxin regulation prevents random toxin activation and promotes fast translational recovery. Nucleic Acids Res. 2012;40:6424–6434. doi: 10.1093/nar/gks297</a></span></span></th> | ||
+ | <td> k<sub>c</sub></th> | ||
+ | <td>1/min 1/molecules</th> | ||
+ | <td>2.0</th> | ||
+ | </tr> | ||
+ | |||
+ | |||
+ | </table> | ||
Line 1,012: | Line 970: | ||
<!--End of modal toxin-antitoxin-system --> | <!--End of modal toxin-antitoxin-system --> | ||
+ | |||
+ | <!--Start of modal model-results --> | ||
+ | <div class="modal fade" id="model-results" tabindex="-1" data-backdrop="false" style="background-color:rgba(0,0,0,0.6);"> | ||
+ | <div class="modal-dialog modal-lg"> | ||
+ | <div class="modal-content"> | ||
+ | <div class="modal-header"> | ||
+ | <button type="button" class="close" data-dismiss="modal">×</button> | ||
+ | <h2 class="modal-title">Modelling Results of the RelE-RelB System</h2> | ||
+ | </div> | ||
+ | <div class="modal-body" margin-right="10%"> | ||
+ | <div class="row"> | ||
+ | <div class="col-md-1"></div> | ||
+ | <div class="col-md-10"> | ||
+ | <p class="P-Larger"><b>Results</b></p><br> | ||
+ | |||
+ | <p>As the bacteria only require a few tens of RelE molecules to enter dormancy, the threshold was placed at 40 copies to allow for lag in activation. This is of course an oversimplification, but it is not a problem that activation and dormancy are defined at different levels, since the exact number of RelE molecules required to induce dormancy is unknown.<br> | ||
+ | <br class="noContent"> | ||
+ | |||
+ | <b>The Impact of Promoters with Different Production Rates on RelE Expression</b><br class="miniBreak"> | ||
+ | During the implementation of RelE, gene expression was simulated for promoters with different strengths, which were chosen through an iterative process. Promoters with production rates of 3.5 and 10.5 molecules per minute, both induce dormancy rather slowly, with the latter inducing dormancy in approximately 50 minutes. In cells cloned with a promoter producing 35 molecules per minute, the cells will enter dormancy in about 10 minutes, while promoters producing 105 and 350 molecules per minute both have a negligible timeframe. In the simulated dormancy system, the three strongest promoters exhibited similar results, indicating that a certain threshold value had been transcended. This means, that not only was the gene expression disproportional to the promoter strength, but the risk of overshooting was also increased tremendously.</p><br> | ||
+ | |||
+ | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/6/6a/T--SDU-Denmark--ren-rele.svg" type="image/svg+xml" style="width:100%;"></object></div> | ||
+ | <br><div class="figure-text"><p><b>Figure #.</b> The increase of free RelE molecules in <i>E. coli</i> cells, after activation of the artificial RelE production. The condition for induced dormancy is an amount of free RelE molecules around tens of copies. The three highest levels of RelE production, correlating with the highest promoter strengths, show little difference in the time at which dormancy occurs. When the RelE production is set to 10.5 molecules per minute, dormancy is induced more slowly and stabilises at lower concentrations. The lowest RelE production value does not trigger dormancy, and has only little effect on the system.</p></div><br class="noContent"> | ||
+ | |||
+ | <p><b>RelB is Required for Activation of Bacteria after Dormant State</b><br class="miniBreak"> | ||
+ | If RelB was not expressed, the bacteria remained dormant for hours after RelE production had ceased, making it clear, that production of the antitoxin RelB was necessary for activation. Considering the stability of RelE in non-growing conditions, it was not surprising to find that RelB production would be the primary element in sequestering free RelE.</p><br> | ||
+ | |||
+ | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/6/6a/T--SDU-Denmark--Wakeup.svg" type="image/svg+xml" style="width:100%;"></object></div> | ||
+ | <br><div class="figure-text"><p><b>Figure #.</b> The decrease in free RelE in dormant bacteria is low without artificial expression of RelB. None of the simulated bacteria reentered an active state within the modelled time.</p></div><br class="noContent"> | ||
+ | |||
+ | <p><b>Appropriate Ratio of RelE and RelB Expression is Essential</b><br class="miniBreak"> | ||
+ | Different expression rates of RelB were combined with production rates of RelE at 35 and 100 molecules per minute, corresponding to relatively medium and strong expression levels respectively. This revealed that variation in RelB had a higher impact on the time required before the dormant state was reached when the RelE production is lowered. Out of the established configurations, the RelB<sub>2</sub>:50-RelE:35 configuration showed promising results. Compared to the RelB<sub>2</sub>:35-RelE:35 configuration, where only few bacteria reenter an active state within the modelled time set to 2.5 hours, the RelB<sub>2</sub>:50-RelE:35 configuration revealed a high sensitivity to the expression level of RelB. This indicated a need for the expression of RelB to be higher than RelE, but as the best results were achieved at low production rates of RelE, it is important to stringently control the expression of RelB to ensure that the bacteria are able to enter dormancy.</p><br> | ||
+ | |||
+ | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/3/37/T--SDU-Denmark--Dormancy-variations.svg" type="image/svg+xml" style="width:100%;"></object></div> | ||
+ | <br><div class="figure-text"><p><b>Figure #.</b> The variation in time required for the bacteria to enter an active state for different expression levels of RelB is dependent on the level of RelE expression. All configurations achieve dormancy within the modelled time.</p></div><br class="noContent"> | ||
+ | |||
+ | |||
+ | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/3/33/T--SDU-Denmark--Reactivation.svg" type="image/svg+xml" style="width:100%;"></object></div> | ||
+ | <br><div class="figure-text"><p><b>Figure #.</b> RelB<sub>2</sub>:50-RelE:35 induces an active state within minutes, whereas RelB:35-RelE:35 only causes few of the bacteria to enter an active state. In the remaining configurations all bacteria remained dormant.</p></div><br class="noContent"> | ||
+ | |||
+ | <br class="noContent"> | ||
+ | |||
+ | <p class="P-Larger"><b>Discussion of Model Regarding the Artificial Dormancy System</b></p><br> | ||
+ | <p><b>Model Limitations</b><br class="miniBreak"> | ||
+ | As the model only simulates the dormancy for 2 hours, not all configurations have reached equilibrium, therefore these configurations might attain a higher concentration of free RelE than modelled. This could result in a prolonged phase reentering an active state. | ||
+ | The activation model has a rather weak predictability, as the half-life of RelE is quite high. This essentially means, that the model is unable to reduce the total amount of RelE, given by RelE<sub>tot</sub>=RelE<sub>free</sub>+RelE<sub>bound</sub>, because of the short simulated timespan. Thus, in activation runs, where the number of free RelE molecules reaches a high level, the amount of RelE<sub>bound</sub> is equally high. The problem arises, since the model works under the assumption that bound RelB is not completely stable, causing RelE-RelB complexes to dissociate, whereby RelE is freed. This causes the induced RelB expression to approach equilibrium, implying that the decrease in free RelE is rather slow. It is therefore not only the amount of free RelE that determines the activation time, but also whether the amount of dissociating complexes is high enough to counter the RelB production. Hence, it has no relevance to further test high RelE production in this model, as a high number of complexes will easily be achieved. <br> | ||
+ | |||
+ | <b>Light Sensitivity</b><br class="miniBreak"> | ||
+ | One thing the model does not include, is the actual sensitivity to light. Out in the open, the amount of light is rarely an on/off switch, which means there will be periods with varying degrees of activation. Since the bacteria should be active during overcast days, the system requires a threshold, both in the sensitivity of the light-regulated promoter, but also in the activation of the toxin-antitoxin system. Variation of light is implicitly modelled through variation in promoter strength, for instance a half probability of activation translates roughly to a half production rate in the individual bacteria. Because of this, it is important not only to find functioning configurations, but also to investigate the closely related configurations, so that the bacteria neither lay dormant at overcast days, nor make the dormancy system obsolete in moonlight. | ||
+ | </p> | ||
+ | |||
+ | </div> | ||
+ | <div class="col-md-1"></div> | ||
+ | </div> | ||
+ | </div> | ||
+ | |||
+ | <div class="modal-footer"> | ||
+ | <a href="" class="btn btn-default" data-dismiss="modal">Close</a> | ||
+ | </div> | ||
+ | </div> | ||
+ | </div> | ||
+ | </div> | ||
+ | <!--End of modal model-results --> | ||
Line 1,026: | Line 1,047: | ||
<p class="P-Larger"><b>Approach</b></p><br> | <p class="P-Larger"><b>Approach</b></p><br> | ||
<p> | <p> | ||
− | In 2004 the <a href="https://2004.igem.org/austin.cgi" target="_blank">Austen and UCSF iGEM team</a> created a <span class="highlighted">device sensitive to light,</span> laying the foundation for the <a href="http://parts.igem.org/Coliroid" target="_blank">Coliroid project</a>. In this project, the <span class="highlighted">system is combined with the RelE-RelB toxin-antitoxin system</span> in the endeavour to mediate <span class="highlighted">light-dependent dormancy in bacteria</span>. As tight regulation is required for the RelE-RelB system <span class= | + | In 2004 the <a href="https://2004.igem.org/austin.cgi" target="_blank">Austen and UCSF iGEM team</a> created a <span class="highlighted">device sensitive to light,</span> laying the foundation for the <a href="http://parts.igem.org/Coliroid" target="_blank">Coliroid project</a>. In this project, the <span class="highlighted">system is combined with the RelE-RelB toxin-antitoxin system</span> in the endeavour to mediate <span class="highlighted">light-dependent dormancy in bacteria</span>. As tight regulation is required for the RelE-RelB system<span class=”reference”><span class="referencetext"><a target="blank" href=”https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3294780/">Tashiro Y, Kawata K, Taniuchi A, Kakinuma K, May T, Okabe S. RelE-Mediated Dormancy Is Enhanced at High Cell Density in Escherichia coli. J Bacteriol. 2012;194(5):1169-76.</a></span></span>, <span class="highlighted">modelling of the toxin-antitoxin system</span>is essential. The impact of different RelE-RelB expression levels was simulated by modelling. Using the results obtained by modelling, a hypothetical working system-design was devised. |
<br> | <br> | ||
On basis of the modulated system, the potential of different vectors and promoters in various combinations was tested. This constitutes the foundation for how the design of the light induced dormancy system in <i>E. coli</i> has been optimized and the final approach shaped. Ultimately, the light-dependent dormancy system, which is illustrated in figure #, was composed of the following parts: | On basis of the modulated system, the potential of different vectors and promoters in various combinations was tested. This constitutes the foundation for how the design of the light induced dormancy system in <i>E. coli</i> has been optimized and the final approach shaped. Ultimately, the light-dependent dormancy system, which is illustrated in figure #, was composed of the following parts: | ||
Line 1,081: | Line 1,102: | ||
<b>Regulation of the OmpR-dependent Promoter Required a Low Copy Vector </b><br> | <b>Regulation of the OmpR-dependent Promoter Required a Low Copy Vector </b><br> | ||
− | The first construct containing the genes required for the light-induced dormancy was designed as shown in figure #. (Reference to first figure) As the conducted modelling clarified, the necessity for stringent regulation of the RelE and RelB expression, the properties of the OmpR-regulated promoter were studied thoroughly. To assess the functionality of the OmpR-regulated promoter in practice, a reporter system containing the OmpR-regulated promoter controlling RFP was cloned into the <i>E. coli</i> strain MG1655 ΔOmpR. The phenotype of the resulting cultures revealed a dysregulation of the OmpR-regulated promoter. Thorough research lead to the finding that the OmpR-dependent promoter is not controllable when cloned on a high copy vector. As the modelling revealed, and which is evident from figure #, a relatively low expression of RelE is required to induce dormancy, whereas high expression levels quickly result in overshooting. Since the OmpR-regulated promoter is an integrated part of the light sensing system, replacement is not an option. Therefore, the variability of the <i>relE</i> gene copy number was studied, and it was found that the OmpR-regulated promoter should be cloned into the bacterial chromosome or a low copy vector to obtain proper regulation <span class= | + | The first construct containing the genes required for the light-induced dormancy was designed as shown in figure #. (Reference to first figure) As the conducted modelling clarified, the necessity for stringent regulation of the RelE and RelB expression, the properties of the OmpR-regulated promoter were studied thoroughly. To assess the functionality of the OmpR-regulated promoter in practice, a reporter system containing the OmpR-regulated promoter controlling RFP was cloned into the <i>E. coli</i> strain MG1655 ΔOmpR. The phenotype of the resulting cultures revealed a dysregulation of the OmpR-regulated promoter. Thorough research lead to the finding that the OmpR-dependent promoter is not controllable when cloned on a high copy vector. As the modelling revealed, and which is evident from figure #, a relatively low expression of RelE is required to induce dormancy, whereas high expression levels quickly result in overshooting. Since the OmpR-regulated promoter is an integrated part of the light sensing system, replacement is not an option. Therefore, the variability of the <i>relE</i> gene copy number was studied, and it was found that the OmpR-regulated promoter should be cloned into the bacterial chromosome or a low copy vector to obtain proper regulation<span class=”reference”><span class="referencetext"><a target="blank" href=”https://www.ncbi.nlm.nih.gov/pubmed/16306980">Levskaya A, Chevalier AA, Tabor JJ, Simpson ZB, Lavery LA, Levy M, et al. Synthetic biology: engineering Escherichia coli to see light. Nature. 2005;438(7067):441-2.</a></span></span>. This intriguing finding let to the aspiration to investigate the controllability of the OmpR-dependent promoter on vectors with different copy numbers compared to the chromosome, thereby improving the characterisation of the promoter for the benefit to future iGEM teams. |
<br> | <br> | ||
− | To incorporate DNA onto the bacterial chromosome, homologous recombination with the red λ recombinase is a suitable approach <span class= | + | To incorporate DNA onto the bacterial chromosome, homologous recombination with the red λ recombinase is a suitable approach<span class=”reference”><span class="referencetext"><a target="blank" href=”https://www.ncbi.nlm.nih.gov/pubmed/2958633">Thompson JF, de Vargas LM, Skinner SE, Landy A. Protein-protein interactions in a higher-order structure direct lambda site-specific recombination. Journal of molecular biology. 1987;195(3):481-93.</a></span></span>. Using this technique, a short fragment of chromosomal DNA at the bacterial attachment site attB<span class=”reference”><span class="referencetext"><a target="blank" href=”https://www.ncbi.nlm.nih.gov/pubmed/14687564">Groth AC, Calos MP. Phage integrases: biology and applications. Journal of molecular biology. 2004;335(3):667-78.</a></span></span>can be replaced with a linear DNA fragment encoding the OmpR-dependent promoter, RelE, and an chloramphenicol resistance cassette. Using polymerase chain reaction (PCR), the linear DNA sequence was flanked by sequences, which are homologous to part of the chromosome. The linear DNA fragment was electroporated into bacteria containing the pKD46 plasmid, encoding the red λ recombinase<span class=”reference”><span class="referencetext"><a target="blank" href=”https://www.ncbi.nlm.nih.gov/pubmed/2958633">Thompson JF, de Vargas LM, Skinner SE, Landy A. Protein-protein interactions in a higher-order structure direct lambda site-specific recombination. Journal of molecular biology. 1987;195(3):481-93.</a></span></span>, which mediated the recombination. The fundamental concept of this approach is illustrated in figure #. |
<br></p> | <br></p> | ||
Line 1,130: | Line 1,151: | ||
− | </div></div> | + | </div> |
+ | </div> | ||
Line 1,148: | Line 1,170: | ||
− | <div class="row margin-bottom-75 | + | <div class="row margin-bottom-75 padding-top-125" id="project-design-carbon-fixation"><div class="col-xs-12"> |
− | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/a/af/T--SDU-Denmark--leaf-icon.svg" type="image/svg+xml"></object><h2>Carbon Fixation</h2></div></div> | + | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/a/af/T--SDU-Denmark--leaf-icon.svg" type="image/svg+xml"></object><h2>Carbon Fixation</h2></div></div><br> |
+ | |||
+ | <div style="text-align:center;"><p><span class="reference-2">Project Overview<span class="referencetext-2"><object data="https://static.igem.org/mediawiki/2017/a/a4/T--SDU-Denmark--project-overview-carbon-fixation.svg" style="width:100%;" type="image/svg+xml"></object></span></span></p></div><br> | ||
+ | |||
+ | |||
<p class="P-Larger"><b>Theory</b></p><br> | <p class="P-Larger"><b>Theory</b></p><br> | ||
<p> | <p> | ||
− | Carbon fixation in autotrophic organisms is responsible for the net fixation of 7×10<sup>16</sup> g carbon annually <span class= | + | Carbon fixation in autotrophic organisms is responsible for the net fixation of 7×10<sup>16</sup> g carbon annually<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Berg+(2011)+Ecological+Aspects+of+the+Distribution+of+Different+Autotrophic+CO2+Fixation+Pathways">Berg IA. Ecological aspects of the distribution of different autotrophic CO2 fixation pathways. Applied and Environmental Microbiology. 2011;77(6):1925-36.</a></span></span>. Six different pathways related to carbon fixation have been discovered, but the most widespread of these, is the Calvin-Benson-Bassham (CBB) cycle found in photosynthetic eukaryotes, e.g. plants and algae, as well as in photo- and chemosynthetic bacteria<span class=”reference”><span class="referencetext"><a target="blank" href="https://books.google.dk/books?id=puEsBAAAQBAJ&pg=PA21&lpg=PA21&dq=calvin+cycle+most+widespread&source=bl&ots=8QGIRwvzDj&sig=7jfO_H3MSc67XxB8xRM3nVdavdA&hl=en&sa=X&ved=0ahUKEwj64OL0-pXVAhXrbZoKHbEWCzcQ6AEINjAD#v=onepage&q=cyano&f=false">B. Bowien MG, R. Klintworth, U. Windhövel. Metabolic and Molecular Regulation of the CO2-assimilating Enzyme System in Aerobic Chemoautotrophs. Microbial Growth on C1 Compounds: Proceedings of the 5th International Symposion. 1st ed. Institute for Microbiology, Georg-August-University Göttingen, Federal Republic of Germany: Martinus Nijhoff Publishers; 1987.</a></span></span>. <span class="highlighted">Out of the eleven enzymes needed for the Calvin cycle, only three are heterologous to <i>E. coli</i></span>, namely; ribulose-1,5-bisphosphate carboxylase/oxygenase (<span class="highlighted">RuBisCo</span>), sedoheptulose-1,7-bisphosphatase (<span class="highlighted">SBPase</span>) and phosphoribulokinase (<span class="highlighted">PRK</span>). By the concurrent heterologous expression of the three genes encoding these enzymes, <i>E. coli</i> can be engineered to perform the full Calvin cycle.</p> |
<br> | <br> | ||
<div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/c/c2/T--SDU-Denmark--calvin-cycle.svg" type="image/svg+xml" style="width:75%;"></object></div> | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/c/c2/T--SDU-Denmark--calvin-cycle.svg" type="image/svg+xml" style="width:75%;"></object></div> | ||
<br><div class="figure-text"><p><b>Figure #.</b> A simplified illustration of the Calvin cycle, with the enzymes heterologous to <i>E. coli</i> and their respective substrates and products shown.</p></div><br class="noContent"> | <br><div class="figure-text"><p><b>Figure #.</b> A simplified illustration of the Calvin cycle, with the enzymes heterologous to <i>E. coli</i> and their respective substrates and products shown.</p></div><br class="noContent"> | ||
− | <p>The <span class="highlighted">carboxysome is a microcompartment</span> utilised by many chemoautotrophic bacteria, including cyanobacteria, as a CO<sub>2</sub> accumulating mechanism to <span class="highlighted">increase carbon fixation efficiency </span>. This organelle-like polyhedral body is able to increase the internal concentrations of inorganic carbon by 4000-fold compared to the external concentration <span class= | + | <p>The <span class="highlighted">carboxysome is a microcompartment</span> utilised by many chemoautotrophic bacteria, including cyanobacteria, as a CO<sub>2</sub> accumulating mechanism to <span class="highlighted">increase carbon fixation efficiency </span>. This organelle-like polyhedral body is able to increase the internal concentrations of inorganic carbon by 4000-fold compared to the external concentration<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027813/">Mangan NM, Brenner MP. Systems analysis of the CO(2) concentrating mechanism in cyanobacteria. eLife. 2014;3.</a></span></span>. One type of carboxysome, is the ɑ-carboxysome, which consists of a proteinaceous outer shell composed of <span class="highlighted">six different shell proteins designated CsoS1ABCD and CsoS4AB. This shell encloses RuBisCo, the shell associated protein (CsoS2), and the enzyme carbonic anhydrase (CsoS3)</span>. In the proteobacteria <i>Halothiobacillus neapolitanus</i>, these genes are clustered into the <span class="highlighted"><i>cso</i> operon</span>. The carbonic anhydrase converts HCO<sub>3</sub><sup>-</sup>, which diffuses passively into the carboxysome, to CO<sub>2</sub>, thereby driving the continued diffusion of HCO<sub>3</sub><sup>-</sup> into the microcompartment<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027813/">Mangan NM, Brenner MP. Systems analysis of the CO(2) concentrating mechanism in cyanobacteria. eLife. 2014;3.</a></span></span>. The increased CO<sub>2</sub> concentration in the vicinity of RuBisCo increases the rate of carbon fixation by saturating the RuBisCo enzyme and increasing the CO<sub>2</sub> to O<sub>2</sub> ratio, enabling carboxylation to dominate over oxygenation<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027813/">Mangan NM, Brenner MP. Systems analysis of the CO(2) concentrating mechanism in cyanobacteria. eLife. 2014;3.</a></span></span>. The shell associated protein is essential for the biogenesis of the ɑ-carboxysome<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/25826651">Cai F, Dou Z, Bernstein SL, Leverenz R, Williams EB, Heinhorst S, et al. Advances in Understanding Carboxysome Assembly in Prochlorococcus and Synechococcus Implicate CsoS2 as a Critical Component. Life (Basel, Switzerland). 2015;5(2):1141-71.</a></span></span>.</p><br> |
<div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/7/73/T--SDU-Denmark--carboxysome.svg" type="image/svg+xml" style="width:70%;"></object></div> | <div style="text-align:center;"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/7/73/T--SDU-Denmark--carboxysome.svg" type="image/svg+xml" style="width:70%;"></object></div> | ||
<br><div class="figure-text"><p><b>Figure #.</b> An illustration of the ɑ-carboxysome. The shell proteins CsoS1ABC and CsoS4AB enclose the enzymes RuBisCo and carbonic anhydrase.</p></div><br class="noContent"> | <br><div class="figure-text"><p><b>Figure #.</b> An illustration of the ɑ-carboxysome. The shell proteins CsoS1ABC and CsoS4AB enclose the enzymes RuBisCo and carbonic anhydrase.</p></div><br class="noContent"> | ||
− | <p><span class="highlighted">For the Calvin cycle to proceed, energy in the form of ATP and electrons carried by NADPH are required</span>. The photosystems are complexes in photosynthesising organisms that can supply this by photophosphorylation. To engineer <i>E. coli</i> to do photosynthesis, 13 genes is needed for the assembly of chlorophyll a and 17 genes for the assembly of photosystem II, which needs to be heterogeneously expressed. An alternative process, in which a diverse array of phototrophic bacteria and archaea harvest energy from light, is through a retinal-containing protein called proteorhodopsin, which catalyses the light-activated proton efflux across the cell membrane and thereby drive ATP synthesis. Opposed to the photosystems, the proteorhodopsin is anoxygenic and generates no NADPH, which is crucial for the Calvin cycle to proceed <span class= | + | <p><span class="highlighted">For the Calvin cycle to proceed, energy in the form of ATP and electrons carried by NADPH are required</span>. The photosystems are complexes in photosynthesising organisms that can supply this by photophosphorylation. To engineer <i>E. coli</i> to do photosynthesis, 13 genes is needed for the assembly of chlorophyll a and 17 genes for the assembly of photosystem II, which needs to be heterogeneously expressed. An alternative process, in which a diverse array of phototrophic bacteria and archaea harvest energy from light, is through a retinal-containing protein called proteorhodopsin, which catalyses the light-activated proton efflux across the cell membrane and thereby drive ATP synthesis. Opposed to the photosystems, the proteorhodopsin is anoxygenic and generates no NADPH, which is crucial for the Calvin cycle to proceed<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892948/">Walter JM, Greenfield D, Bustamante C, Liphardt J. Light-powering Escherichia coli with proteorhodopsin. Proceedings of the National Academy of Sciences of the United States of America. 2007;104(7):2408-12.</a></span></span>. For further information about the theory behind the carbon fixation, <span class="btn-link btn-lg" data-toggle="modal" data-target="#co2-fixation-theory">read here</span>. |
</p><br> | </p><br> | ||
Line 1,182: | Line 1,208: | ||
<b>Carbon Fixation through the Calvin Cycle</b> | <b>Carbon Fixation through the Calvin Cycle</b> | ||
<br> | <br> | ||
− | Carbon fixation in autotrophic organisms is responsible for the net fixation of 7×10<sup>16</sup> g carbon annually, thereby being the most imperative biosynthetic process in nature <span class= | + | Carbon fixation in autotrophic organisms is responsible for the net fixation of 7×10<sup>16</sup> g carbon annually, thereby being the most imperative biosynthetic process in nature<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Berg+(2011)+Ecological+Aspects+of+the+Distribution+of+Different+Autotrophic+CO2+Fixation+Pathways">Berg IA. Ecological aspects of the distribution of different autotrophic CO2 fixation pathways. Applied and Environmental Microbiology. 2011;77(6):1925-36.</a></span></span>. Six different autotrophic pathways for carbon fixation have been discovered in a variety of organisms<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3424341/">Ducat DC, Silver PA. Improving Carbon Fixation Pathways. Current opinion in chemical biology. 2012;16(3-4):337-44.</a></span></span>. The most widespread of these, is the Calvin-Benson-Bassham (CBB) cycle, found in photosynthetic eukaryotes, e.g. plants and algae, as well as in photo- and chemosynthetic bacteria<span class=”reference”><span class="referencetext"><a target="blank" href="https://books.google.dk/books?id=puEsBAAAQBAJ&pg=PA21&lpg=PA21&dq=calvin+cycle+most+widespread&source=bl&ots=8QGIRwvzDj&sig=7jfO_H3MSc67XxB8xRM3nVdavdA&hl=en&sa=X&ved=0ahUKEwj64OL0-pXVAhXrbZoKHbEWCzcQ6AEINjAD#v=onepage&q=cyano&f=false">B. Bowien MG, R. Klintworth, U. Windhövel. Metabolic and Molecular Regulation of the CO2-assimilating Enzyme System in Aerobic Chemoautotrophs. Microbial Growth on C1 Compounds: Proceedings of the 5th International Symposion. 1st ed. Institute for Microbiology, Georg-August-University Göttingen, Federal Republic of Germany: Martinus Nijhoff Publishers; 1987.</a></span></span>. The Calvin cycle, as this pathway is also called, can proceed under aerobic conditions, and only three enzymes and one microcompartment involved are heterologous to the gram-negative bacteria <i>E. coli</i>, making this the most obvious choice for the implementation of a carbon fixation pathway. In contrast, the 3-hydroxypropionate pathway for CO<sub>2</sub> fixation would require the transfer of ten heterologous genes<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/23376595">1. Mattozzi M, Ziesack M, Voges MJ, Silver PA, Way JC. Expression of the sub-pathways of the Chloroflexus aurantiacus 3-hydroxypropionate carbon fixation bicycle in E. coli: Toward horizontal transfer of autotrophic growth. Metabolic engineering. 2013;16:130-9.</a></span></span>. Furthermore, the reductive carboxylic acid cycle found in phylogenetically diverse autotrophic bacteria and archaea<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Evidence+for+Autotrophic+CO2+Fixation+via+the+Reductive+Tricarboxylic+Acid+Cycle+by+Members+of+the+%CE%B5+Subdivision+of+Proteobacteria%E2%80%A0">Hugler M, Wirsen CO, Fuchs G, Taylor CD, Sievert SM. Evidence for autotrophic CO2 fixation via the reductive tricarboxylic acid cycle by members of the epsilon subdivision of proteobacteria. J Bacteriol. 2005;187(9):3020-7.</a></span></span>and the noncyclic reductive acetyl-CoA or Wood-Ljungdahl pathway<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2646786/">Ragsdale SW, Pierce E. Acetogenesis and the Wood-Ljungdahl Pathway of CO(2) Fixation. Biochimica et biophysica acta. 2008;1784(12):1873-98.</a></span></span>require strict anaerobic conditions. <br> |
− | The Calvin cycle involves eleven enzymes, of which eight are intrinsic to <i>E. coli</i>. The three heterologous enzymes are RuBisCo, SBPase and PRK. The latter phosphorylates ribulose-5-phosphate to ribulose-1,5-bisphosphate. This is the substrate for RuBisCo, which catalyses the carboxylation, whereby glycerate-3-phosphate is produced. Later in the cycle, SBPase catalyses the dephosphorylation of sedoheptulose-1,7-bisphosphate to sedoheptulose-7-phosphate, which is later converted to ribulose-5-phosphate, completing the circle. The net effect of three full cycles is the conversion of three CO<sub>2</sub> molecules into one molecule glyceraldehyde-3-phosphate, which can be used for energy production via glycolysis or polysaccharide biosynthesis. Separately, these enzymes have previously been heterogeneously expressed in <i>E. coli</i> using various donor species, such as wheat <span class= | + | The Calvin cycle involves eleven enzymes, of which eight are intrinsic to <i>E. coli</i>. The three heterologous enzymes are RuBisCo, SBPase and PRK. The latter phosphorylates ribulose-5-phosphate to ribulose-1,5-bisphosphate. This is the substrate for RuBisCo, which catalyses the carboxylation, whereby glycerate-3-phosphate is produced. Later in the cycle, SBPase catalyses the dephosphorylation of sedoheptulose-1,7-bisphosphate to sedoheptulose-7-phosphate, which is later converted to ribulose-5-phosphate, completing the circle. The net effect of three full cycles is the conversion of three CO<sub>2</sub> molecules into one molecule glyceraldehyde-3-phosphate, which can be used for energy production via glycolysis or polysaccharide biosynthesis. Separately, these enzymes have previously been heterogeneously expressed in <i>E. coli</i> using various donor species, such as wheat<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/9758762">Dunford RP, Catley MA, Raines CA, Lloyd JC, Dyer TA. Purification of active chloroplast sedoheptulose-1,7-bisphosphatase expressed in Escherichia coli. Protein expression and purification. 1998;14(1):139-45.</a></span></span>, the algae <i>Chlamydomonas sp.</i><span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/15849430">Tamoi M, Nagaoka M, Shigeoka S. Immunological properties of sedoheptulose-1,7-bisphosphatase from Chlamydomonas sp. W80. Bioscience, biotechnology, and biochemistry. 2005;69(4):848-51.</a></span></span><span class="reference"><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/26828117">Vira C, Prakash G, Rathod JP, Lali AM. Cloning, expression, and purification of Chlamydomonas reinhardtii CC-503 sedoheptulose 1,7-bisphosphatase in Escherichia coli. Preparative biochemistry & biotechnology. 2016;46(8):810-4.</a></span></span>, and the cyanobacteria <i>Synechococcus</i><span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/16423843">Parikh MR, Greene DN, Woods KK, Matsumura I. Directed evolution of RuBisCO hypermorphs through genetic selection in engineered E.coli. Protein engineering, design & selection : PEDS. 2006;19(3):113-9.</a></span></span>. <br> |
<br class="noContent"> | <br class="noContent"> | ||
Line 1,191: | Line 1,217: | ||
<b>The Carboxysome Increases the Efficiency of the Carboxylation by RuBisCo</b> | <b>The Carboxysome Increases the Efficiency of the Carboxylation by RuBisCo</b> | ||
<br> | <br> | ||
− | Many photosynthesising bacteria have developed CO<sub>2</sub> concentrating mechanisms to increase the efficiency of the carbon fixation process. Cyanobacteria and many chemoautotrophic bacteria utilise organelle-like polyhedral bodies, that increase the internal concentrations of inorganic carbon 4000-fold compared to external levels | + | Many photosynthesising bacteria have developed CO<sub>2</sub> concentrating mechanisms to increase the efficiency of the carbon fixation process. Cyanobacteria and many chemoautotrophic bacteria utilise organelle-like polyhedral bodies, that increase the internal concentrations of inorganic carbon 4000-fold compared to external levels <span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027813/">Mangan NM, Brenner MP. Systems analysis of the CO(2) concentrating mechanism in cyanobacteria. eLife. 2014;3.</a></span></span>. These microcompartments, called carboxysomes, appear to have arisen twice during evolution and have undergone a process of convergent evolution<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3811607/">Rae BD, Long BM, Badger MR, Price GD. Functions, Compositions, and Evolution of the Two Types of Carboxysomes: Polyhedral Microcompartments That Facilitate CO(2) Fixation in Cyanobacteria and Some Proteobacteria. Microbiology and Molecular Biology Reviews : MMBR. 2013;77(3):357-79.</a></span></span>. The two types, designated ɑ and β, share main structural and functional features<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3811607/">Rae BD, Long BM, Badger MR, Price GD. Functions, Compositions, and Evolution of the Two Types of Carboxysomes: Polyhedral Microcompartments That Facilitate CO(2) Fixation in Cyanobacteria and Some Proteobacteria. Microbiology and Molecular Biology Reviews : MMBR. 2013;77(3):357-79.</a></span></span>. The ɑ-carboxysome consists of a proteinaceous outer shell composed of six different shell proteins designated CsoS1ABCD and CsoS4AB, and encloses RuBisCo, the shell associated protein CsoS2, and the enzyme carbonic anhydrase CsoS3. On average, ~250 RuBisCo molecules are localised within each carboxysome, and these are organised into three to four concentric layers<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/17669419">Iancu CV, Ding HJ, Morris DM, Dias DP, Gonzales AD, Martino A, et al. The structure of isolated Synechococcus strain WH8102 carboxysomes as revealed by electron cryotomography. Journal of molecular biology. 2007;372(3):764-73.</a></span></span>. The carbonic anhydrase converts HCO<sub>3</sub><sup>-</sup>, which diffuses passively into the carboxysome, to CO<sub>2</sub>, thereby driving the continued diffusion of HCO<sub>3</sub><sup>-</sup> into the microcompartment<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027813/">Mangan NM, Brenner MP. Systems analysis of the CO(2) concentrating mechanism in cyanobacteria. eLife. 2014;3.</a></span></span>. The increased CO<sub>2</sub> concentration in the vicinity of RuBisCo increases the rate of carbon fixation by saturating the RuBisCo enzyme and increasing the CO<sub>2</sub> to O<sub>2</sub> ratio, enabling carboxylation to prevail over oxygenation<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027813/">Mangan NM, Brenner MP. Systems analysis of the CO(2) concentrating mechanism in cyanobacteria. eLife. 2014;3.</a></span></span>. The shell associated protein is essential for the biogenesis of the ɑ-carboxysome<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/25826651">Cai F, Dou Z, Bernstein SL, Leverenz R, Williams EB, Heinhorst S, et al. Advances in Understanding Carboxysome Assembly in Prochlorococcus and Synechococcus Implicate CsoS2 as a Critical Component. Life (Basel, Switzerland). 2015;5(2):1141-71.</a></span></span>. The genes encoding the enzymes and shell proteins forming the ɑ-carboxysome from <i>Halothiobacillus neapolitanus</i> are clustered into the <i>cso</i> operon. This operon has been heterogeneously expressed in <i>E. coli</i> and its transcriptional regulation<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/17899012">Cai F, Heinhorst S, Shively JM, Cannon GC. Transcript analysis of the Halothiobacillus neapolitanus cso operon. Archives of microbiology. 2008;189(2):141-50.</a></span></span>and functionality<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/22184212">Bonacci W, Teng PK, Afonso B, Niederholtmeyer H, Grob P, Silver PA, et al. Modularity of a carbon-fixing protein organelle. Proceedings of the National Academy of Sciences of the United States of America. 2012;109(2):478-83.</a></span></span>has been studied. |
<br> | <br> | ||
Line 1,198: | Line 1,224: | ||
<b>Energy and Electrons are Required for Carbon Fixation</b><br> | <b>Energy and Electrons are Required for Carbon Fixation</b><br> | ||
− | For the Calvin cycle to proceed, energy in the form of ATP and electrons carried by NADPH are required. In photosynthesising organisms, such as plants and cyanobacteria, these constituents are provided by photophosphorylation performed by the photosystem complex. When engineering <i>E. coli</i> to perform photophosphorylation, 13 genes for the biosynthesis of chlorophyll a and 17 genes for the biosynthesis of photosystem II need to be heterogeneously expressed. Several attempts have been made at expressing part of it, such as the <i>psbA</i> gene <span class= | + | For the Calvin cycle to proceed, energy in the form of ATP and electrons carried by NADPH are required. In photosynthesising organisms, such as plants and cyanobacteria, these constituents are provided by photophosphorylation performed by the photosystem complex. When engineering <i>E. coli</i> to perform photophosphorylation, 13 genes for the biosynthesis of chlorophyll a and 17 genes for the biosynthesis of photosystem II need to be heterogeneously expressed. Several attempts have been made at expressing part of it, such as the <i>psbA</i> gene<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/8053946">Efimov VA, Reverdatto SV, Beilinson BA, Fradkov AF, Chakhmakhcheva OG. [Expression of the gene coding for the D1-protein of barley photosystem II in Escherichia coli]. Bioorganicheskaia khimiia. 1994;20(5):524-35.</a></span></span>and the 18-kDa protein of photosystem II<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/7757336">Kuwabara T, Takeuchi M, Honda S, Nakajima N, Watanabe A, Kondo N. Expression in Escherichia coli of the extrinsic 18-kDa protein of photosystem II of spinach. Plant & cell physiology. 1995;36(3):435-9.</a></span></span>, both of which was successful. |
<br> | <br> | ||
− | An alternative process, in which a diverse array of phototrophic bacteria and archaea harvest energy from light, is through a retinal-containing protein, called proteorhodopsin, that catalyse light-activated proton efflux across the cell membrane and thereby drive ATP synthesis. In contrast to photosystems, the process involving proteorhodopsin is anoxygenic and generates no NADPH vital for the Calvin cycle to proceed <span class= | + | An alternative process, in which a diverse array of phototrophic bacteria and archaea harvest energy from light, is through a retinal-containing protein, called proteorhodopsin, that catalyse light-activated proton efflux across the cell membrane and thereby drive ATP synthesis. In contrast to photosystems, the process involving proteorhodopsin is anoxygenic and generates no NADPH vital for the Calvin cycle to proceed<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892948/">Walter JM, Greenfield D, Bustamante C, Liphardt J. Light-powering Escherichia coli with proteorhodopsin. Proceedings of the National Academy of Sciences of the United States of America. 2007;104(7):2408-12.</a></span></span>. The heterologous expression of this light-powered proton pump in <i>E. coli</i> enabled photophosphorylation when the bacteria were exposed to light<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1838496/">Martinez A, Bradley AS, Waldbauer JR, Summons RE, DeLong EF. Proteorhodopsin photosystem gene expression enables photophosphorylation in a heterologous host. Proceedings of the National Academy of Sciences of the United States of America. 2007;104(13):5590-5. |
</a></span></span> | </a></span></span> | ||
− | , and even generated a proton motive force, which turned the flagellar motor, yielding light-dependent motility <span class= | + | , and even generated a proton motive force, which turned the flagellar motor, yielding light-dependent motility<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892948/">Walter JM, Greenfield D, Bustamante C, Liphardt J. Light-powering Escherichia coli with proteorhodopsin. Proceedings of the National Academy of Sciences of the United States of America. 2007;104(7):2408-12.</a></span></span>. |
</p> | </p> | ||
Line 1,295: | Line 1,321: | ||
− | <div class="row margin-bottom-75 | + | <div class="row margin-bottom-75 padding-top-125" id="project-design-cellulose-biosynthesis"><div class="col-xs-12"> |
− | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/8/83/T--SDU-Denmark--cellulose-icon.svg" type="image/svg+xml"></object><h2>Cellulose Biosynthesis</h2></div></div> | + | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/8/83/T--SDU-Denmark--cellulose-icon.svg" type="image/svg+xml"></object><h2>Cellulose Biosynthesis</h2></div></div><br> |
+ | |||
+ | <div style="text-align:center;"><p><span class="reference-2">Project Overview<span class="referencetext-2"><object data="https://static.igem.org/mediawiki/2017/2/2a/T--SDU-Denmark--project-overview-cellulose-biosynthesis.svg" style="width:100%;" type="image/svg+xml"></object></span></span></p></div><br> | ||
+ | |||
+ | |||
<p class="P-Larger"><b>Theory</b></p><br> | <p class="P-Larger"><b>Theory</b></p><br> | ||
<p> | <p> | ||
− | <span class="highlighted">Bacterial cellulose is one of the most abundant biopolymers produced by different species of gram-negative bacteria</span>, especially by <i>Acetobactors</i>. <i>Glucoacetobacter xylinus</i> is a bacterial species, which produces cellulose in large quantities of high quality <span class= | + | <span class="highlighted">Bacterial cellulose is one of the most abundant biopolymers produced by different species of gram-negative bacteria</span>, especially by <i>Acetobactors</i>. <i>Glucoacetobacter xylinus</i> is a bacterial species, which produces cellulose in large quantities of high quality<span class=”reference”><span class="referencetext"><a target="blank" href="https://doi.org/10.1007/s10570-013-9994-3">Lin, SP., Loira Calvar, I., Catchmark, J.M. et al. Cellulose (2013) 20: 2191.</a></span></span>. Cellulose is produced from the resource glucose-6-phosphate. This phosphorylated glucose is a key intermediate in the core carbon metabolism of bacteria given its importance in glycolysis, gluconeogenesis and pentose phosphate pathway<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.amazon.com/Prescotts-Microbiology-Joanne-Willey/dp/0073402400">Joanne Willey LS, Christopher J. Woolverton. Prescott’s Microbiology. 9th edition 2014.</a></span></span>. Even though the pathway, where glucose and glucose-6-phosphate is converted into cellulose, only includes few steps, it requires a great amount of energy. Not only does the cell spend energy on forming UDP-glucose for cellulose biosynthesis, it also uses glucose, which otherwise would have contributed to generation of ATP<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/27247386">Florea M, Hagemann H, Santosa G, Abbott J, Micklem CN, Spencer-Milnes X, et al. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain. Proceedings of the National Academy of Sciences of the United States of America. 2016;113(24):E3431-40.</a></span></span>. |
<br> | <br> | ||
− | <span class="highlighted">The ability for <i>G. xylinus</i> to produce cellulose nanofibers from UDP-glucose, crystallize, and secrete it, is controlled by genes in the Acetobacter cellulose synthase (acs) operon <i>acsABCD</i></span>. This operon encodes four different proteins: AcsA, AcsB, AcsC and AcsD. A dimer, known as AcsAB, is formed by a catalytic domain, AcsA, and a regulatory domain, AcsB. This dimer is responsible for synthesising the cellulose nanofibers from UDP-glucose, whereas AcsC and AcsD secretes cellulose and forms an interconnected cellulose pellicle around the cells <span class= | + | <span class="highlighted">The ability for <i>G. xylinus</i> to produce cellulose nanofibers from UDP-glucose, crystallize, and secrete it, is controlled by genes in the Acetobacter cellulose synthase (acs) operon <i>acsABCD</i></span>. This operon encodes four different proteins: AcsA, AcsB, AcsC and AcsD. A dimer, known as AcsAB, is formed by a catalytic domain, AcsA, and a regulatory domain, AcsB. This dimer is responsible for synthesising the cellulose nanofibers from UDP-glucose, whereas AcsC and AcsD secretes cellulose and forms an interconnected cellulose pellicle around the cells<span class=”reference”><span class="referencetext"><a target="blank" href="https://link-springer-com.proxy1-bib.sdu.dk/article/10.1007%2Fs10570-014-0521-y">Mehta K, et al. Characterization of an acsD disruption mutant provides additional evidence for the hierarchical cell-directed self-assembly of cellulose in Gluconacetobacter xylinus. Cellulose. 2014;22:119–137.</a></span></span>, as illustrated in figure #. |
</p><br> | </p><br> | ||
Line 1,307: | Line 1,337: | ||
<br><div class="figure-text"><p><b>Figure #.</b> The AcsAB dimer synthesises cellulose nanofibers. AcsC and AcsD mediate the secretion and formation of an interconnected cellulose pellicle.</p></div><br class="noContent"> | <br><div class="figure-text"><p><b>Figure #.</b> The AcsAB dimer synthesises cellulose nanofibers. AcsC and AcsD mediate the secretion and formation of an interconnected cellulose pellicle.</p></div><br class="noContent"> | ||
− | <p>Other genera, including some <i>E. coli</i> strains, secrete cellulose as a component of their biofilm. Even though cellulose biosynthesis is intrinsic to <i>E. coli</i>, the quantity of the production is incomparable to cellulose biosynthesis in <i>G. xylinus</i>. Indigenously, <i>E. coli</i> is not capable of degrading cellulose into a metabolisable energy source <span class= | + | <p>Other genera, including some <i>E. coli</i> strains, secrete cellulose as a component of their biofilm. Even though cellulose biosynthesis is intrinsic to <i>E. coli</i>, the quantity of the production is incomparable to cellulose biosynthesis in <i>G. xylinus</i>. Indigenously, <i>E. coli</i> is not capable of degrading cellulose into a metabolisable energy source<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/26452465">Gao D, Luan Y, Wang Q, Liang Q, Qi Q. Construction of cellulose-utilizing Escherichia coli based on a secretable cellulase. Microbial Cell Factories. 2015;14:159.</a></span></span>. However, if this structural and water-holding polymer is enzymatically degraded, first into cellobiose and then to glucose residues, the cellulose polymer is a potent source of energy<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/17244702"> Arai T, Matsuoka S, Cho HY, |
Yukawa H, Inui M, Wong SL, et al. Synthesis of Clostridium cellulovorans | Yukawa H, Inui M, Wong SL, et al. Synthesis of Clostridium cellulovorans | ||
minicellulosomes by intercellular complementation. Proceedings of the National | minicellulosomes by intercellular complementation. Proceedings of the National | ||
Line 1,326: | Line 1,356: | ||
<p class="P-Larger"><b>Approach</b></p><br> | <p class="P-Larger"><b>Approach</b></p><br> | ||
<p style="width:100%;"> | <p style="width:100%;"> | ||
− | To <span class="highlighted">link the two bacterial compartments of the PowerLeaf</span>, an efficient way to <span class="highlighted">store the harvested energy</span> was required. Research led to the finding that storing the chemical energy in <span class="highlighted">cellulose would be a suitable approach</span>, since this is a polysaccharide that bacteria normally are unable to degrade <span class= | + | To <span class="highlighted">link the two bacterial compartments of the PowerLeaf</span>, an efficient way to <span class="highlighted">store the harvested energy</span> was required. Research led to the finding that storing the chemical energy in <span class="highlighted">cellulose would be a suitable approach</span>, since this is a polysaccharide that bacteria normally are unable to degrade<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/26452465">Gao D, Luan Y, Wang Q, Liang Q, Qi Q. Construction of cellulose-utilizing Escherichia coli based on a secretable cellulase. Microbial Cell Factories. 2015;14:159.</a></span></span>. After looking into earlier iGEM projects it was found that the |
− | <a href="https://2014.igem.org/Team:Imperial" target="_blank">2014 project Aqualose from Imperial College London</a>, had worked with optimisation of cellulose biosynthesis in <i>E. coli</i>. Our aim was to <span class="highlighted">enhance cellulose biosynthesis in <i>E. coli</i> MG1655</span>, which naturally secretes small amounts of cellulose as a part of its biofilm <span class= | + | <a href="https://2014.igem.org/Team:Imperial" target="_blank">2014 project Aqualose from Imperial College London</a>, had worked with optimisation of cellulose biosynthesis in <i>E. coli</i>. Our aim was to <span class="highlighted">enhance cellulose biosynthesis in <i>E. coli</i> MG1655</span>, which naturally secretes small amounts of cellulose as a part of its biofilm<span class=”reference”><span class="referencetext"><a target="blank" href="https://www.ncbi.nlm.nih.gov/pubmed/18599830">Gualdi L, Tagliabue L, Bertagnoli S, Ierano T, De Castro C, Landini P. Cellulose modulates biofilm formation by counteracting curli-mediated colonization of solid surfaces in Escherichia coli. Microbiology (Reading, England). 2008;154(Pt 7):2017-24.</a></span></span>. This would be achieved by the cloning of plasmids containing the <span class="highlighted">cellulose synthase operon <i>acsABCD</i></span>, utilising the two parts <a href="http://parts.igem.org/Part:BBa_K1321334" target="_blank">BBa_K1321334</a> and <a href="http://parts.igem.org/Part:BBa_K1321335" target="_blank">BBa_K1321335</a>, constructed by Imperial College London 2014. This would enhance the cellulose biosynthesis and thereby optimise the energy outcome of the entire system in our project. |
Due to cloning difficulties, it was decided to prioritise other aspects of the project and therefore <span class="highlighted">keep this part theoretical henceforth</span>. For further information about the cellulose biosynthesis approach, <span class="btn-link btn-lg" data-toggle="modal" data-target="#cellulose-production-approach">read here</span>. | Due to cloning difficulties, it was decided to prioritise other aspects of the project and therefore <span class="highlighted">keep this part theoretical henceforth</span>. For further information about the cellulose biosynthesis approach, <span class="btn-link btn-lg" data-toggle="modal" data-target="#cellulose-production-approach">read here</span>. | ||
</p><br> | </p><br> | ||
Line 1,333: | Line 1,363: | ||
</div></div> | </div></div> | ||
− | <!--Start of modal | + | <!--Start of modal cellulose biosynthesis approach--> |
<div class="modal fade" id="cellulose-production-approach" tabindex="-1" data-backdrop="false" style="background-color:rgba(0,0,0,0.6);"> | <div class="modal fade" id="cellulose-production-approach" tabindex="-1" data-backdrop="false" style="background-color:rgba(0,0,0,0.6);"> | ||
<div class="modal-dialog modal-lg"> | <div class="modal-dialog modal-lg"> | ||
Line 1,357: | Line 1,387: | ||
<p>In this design, it was attempted to implement the <i>acsABCD</i> operon into <i>E. coli</i> MG1655 on two separate vectors, with both parts controlled by Ptac<a href="http://parts.igem.org/Part:BBa_K864400" target="_blank">BBa_K864400</a>, ensuring equal expression levels of the parts. The AcsAB dimer, encoded in the part <a href="http://parts.igem.org/Part:BBa_K1321334" target="_blank">BBa_K1321334</a>, was attempted to be inserted into the vector pSB1C3. The part <a href="http://parts.igem.org/Part:BBa_K1321335" target="_blank">BBa_K1321335</a>, containing AcsC and AcsD, was inserted into the vector pSB1A3. Several combinations of the two parts and different vectors carrying different resistance cassettes were attempted, but unfortunately without success. Correspondence with a supervisor from the <a href="https://2014.igem.org/Team:Imperial" target="_blank">Imperial College London team</a>, revealed that cloning with these parts had emerged difficult for them as well. Due to time constraints, it was decided to prioritise other aspects of the project and therefore keep this part theoretical henceforth. | <p>In this design, it was attempted to implement the <i>acsABCD</i> operon into <i>E. coli</i> MG1655 on two separate vectors, with both parts controlled by Ptac<a href="http://parts.igem.org/Part:BBa_K864400" target="_blank">BBa_K864400</a>, ensuring equal expression levels of the parts. The AcsAB dimer, encoded in the part <a href="http://parts.igem.org/Part:BBa_K1321334" target="_blank">BBa_K1321334</a>, was attempted to be inserted into the vector pSB1C3. The part <a href="http://parts.igem.org/Part:BBa_K1321335" target="_blank">BBa_K1321335</a>, containing AcsC and AcsD, was inserted into the vector pSB1A3. Several combinations of the two parts and different vectors carrying different resistance cassettes were attempted, but unfortunately without success. Correspondence with a supervisor from the <a href="https://2014.igem.org/Team:Imperial" target="_blank">Imperial College London team</a>, revealed that cloning with these parts had emerged difficult for them as well. Due to time constraints, it was decided to prioritise other aspects of the project and therefore keep this part theoretical henceforth. | ||
<br> | <br> | ||
− | If the cloning of the <i>acsABCD</i> operon had been successful, the cellulose biosynthesis would have been tested using fluorescent brightener 28. This is a colourless organic compound that fluoresces with a bright blue color under ultraviolet radiation, and it is used as a fluorescent brightening agent for polyamide and cellulose fabrics. Fluorescent brightener 28 binds non-specifically to polysaccharides with β-1,3 and β-1,4 linkages, of which the latter is present in cellulose <span class= | + | If the cloning of the <i>acsABCD</i> operon had been successful, the cellulose biosynthesis would have been tested using fluorescent brightener 28. This is a colourless organic compound that fluoresces with a bright blue color under ultraviolet radiation, and it is used as a fluorescent brightening agent for polyamide and cellulose fabrics. Fluorescent brightener 28 binds non-specifically to polysaccharides with β-1,3 and β-1,4 linkages, of which the latter is present in cellulose<span class=”reference”><span class="referencetext"><a target="blank" href="http://www.pern-brio.eu/protocols/protocol-calcofluor-mut.pdf">Staining of fungal hyphae and propagules with fluorescent brightener</a></span></span>. |
</p> | </p> | ||
Line 1,372: | Line 1,402: | ||
</div> | </div> | ||
</div> | </div> | ||
− | <!--End of modal | + | <!--End of modal cellulose biosynthesis approach --> |
Line 1,389: | Line 1,419: | ||
− | <div class="row margin-bottom-75 | + | <div class="row margin-bottom-75 padding-top-125" id="project-design-cellulose-breakdown"><div class="col-xs-12"> |
− | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/f/f8/T--SDU-Denmark--enzyme-icon.svg" type="image/svg+xml"></object><h2>Breakdown of Cellulose</h2></div></div> | + | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/f/f8/T--SDU-Denmark--enzyme-icon.svg" type="image/svg+xml"></object><h2>Breakdown of Cellulose</h2></div></div><br> |
+ | |||
+ | |||
+ | <div style="text-align:center;"><p><span class="reference-2">Project Overview<span class="referencetext-2"><object data="https://static.igem.org/mediawiki/2017/0/09/T--SDU-Denmark--project-overview-cellulose-breakdown.svg" style="width:100%;" type="image/svg+xml"></object></span></span></p></div><br> | ||
+ | |||
+ | |||
<p class="P-Larger"><b><span class="highlighted">Theory</span></b></p><br> | <p class="P-Larger"><b><span class="highlighted">Theory</span></b></p><br> | ||
<p> | <p> | ||
Line 1,478: | Line 1,513: | ||
− | <div class="row | + | <div class="row padding-top-125" id="project-design-extracellular-electron-transfer"><div class="col-xs-12"> |
− | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/9/9b/T--SDU-Denmark--power-icon.svg" type="image/svg+xml"></object><h2>Extracellular Electron Transfer</h2></div></div> | + | <div class="row"><div class="project-design-headline"><object class="highlighted-image project-design-icon" data="https://static.igem.org/mediawiki/2017/9/9b/T--SDU-Denmark--power-icon.svg" type="image/svg+xml"></object><h2>Extracellular Electron Transfer</h2></div></div><br> |
+ | |||
+ | |||
+ | <div style="text-align:center;"><p><span class="reference-2">Project Overview<span class="referencetext-2"><object data="https://static.igem.org/mediawiki/2017/5/58/T--SDU-Denmark--project-overview-nanowires.svg" style="width:100%;" type="image/svg+xml"></object></span></span></p></div><br> | ||
+ | |||
+ | |||
<p class="P-Larger"><b>Theory</b></p><br> | <p class="P-Larger"><b>Theory</b></p><br> | ||
<p> | <p> | ||
Line 1,753: | Line 1,793: | ||
<b>Week 14</b><br class="miniBreak"> | <b>Week 14</b><br class="miniBreak"> | ||
− | Through an iterative process, the list of project ideas was cut down. Ultimately, the PowerLeaf - | + | Through an iterative process, the list of project ideas was cut down. Ultimately, the PowerLeaf - A Bacterial Solar Battery was chosen as our project. |
<br> | <br> | ||
<br class="noContent"> | <br class="noContent"> | ||
Line 2,157: | Line 2,197: | ||
<div class="col-md-8 col-xs-10 margin-bottom-200 margin-top-50"> | <div class="col-md-8 col-xs-10 margin-bottom-200 margin-top-50"> | ||
− | <p><span class="largeFirstLetter"> | + | |
− | <br> | + | <div style="text-align:center;"><p class="raleway P-Larger" style="text-align:center;"><i>“Change is the law of life; and those who look only to the past or present are certain to miss the future”</i></p><br><p class="raleway"><i>John F. Kennedy</i></p></div><br><br class="noContent"> |
− | + | ||
− | </p> | + | <p><span class="highlighted"><span class="largeFirstLetter">W</span>elcome to our Human Practices!</span> Now, when it comes to the particulars of our Human Practices, you will find that it has been separated into three main parts. This is all strictly for narrative purposes, as every single aspect of our project and Human Practices, are deeply intertwined through a shared philosophy: If you want change, look to the future! |
+ | </p><br> | ||
+ | <p class="P-Larger"><b>1. A Philosopher’s Guide to the Future</b></p><br class="miniBreak"><p>To ensure an ethically sound iGEM product and experience, we have discussed the ethical considerations that ought to be taken into account. As luck would have it, one of our team members is a philosopher with an interest in bioethics. Thus a guidebook was created, a guide <span class="highlighted">that amongst other things includes an overview of some of the bioethical arguments iGEM participants are likely to encounter, when discussing synthetic biology</span>. You can find these considerations in our section on <a href="#bioethics" target="_blank">Bioethics</a>.</p><br> | ||
+ | <p class="P-Larger"><b>2. An Implementation of the Future</b></p><br class="miniBreak"><p><span class="highlighted">We reached out to our local Municipality of Odense along with various experts, for their advice on the development and implementation of our device in an urban environment</span>. You can read more about this in our section on <a href="#integrated-practices" target="_blank">Integrated Human Practice</a>.</p><br> | ||
+ | <p class="P-Larger"><b>3. A Trip to the Future and Beyond!</b></p><br class="miniBreak"><p>Considering how our main philosophy was: If you want change, look to the future! <span class="highlighted">It seemed prudent to bring our message on sustainability to the next generation</span>. You can read more about our efforts in the section on <a href="#education-and-public-engagement" target="_blank">Education and Public Engagement</a>.</p> | ||
+ | |||
+ | |||
</div> | </div> | ||
Line 2,182: | Line 2,228: | ||
<div class="row border-left-practices"> | <div class="row border-left-practices"> | ||
<div class="col-xs-12"> | <div class="col-xs-12"> | ||
− | <h2><span class="highlighted">Bioethics</span></h2><hr> | + | <h2><span class="highlighted">Bioethics</span></h2><br><h4>- <i>A Philosopher’s Guide to the Future</i></h4><hr> |
− | + | ||
+ | <div style="text-align:center;"><p class="raleway P-Larger" style="text-align:center;"><i>“The facts of life... to make an alteration in the evolvement of an organic life system is fatal. A coding sequence cannot be revised once it's been established.”</i></p><br><p class="raleway"><i>Tyrell, Bladerunner</i></p></div><br><br class="noContent"> | ||
+ | |||
+ | |||
</div> | </div> | ||
− | |||
− | |||
<div class="row"><div class="col-xs-12"> | <div class="row"><div class="col-xs-12"> | ||
− | <p> | + | <p><span class="highlighted">Synthetic biology and the iGEM competition are aimed to help solve societal issues</span>, issues such as agriculture, medical research, and environmental resource management, the last of which has been our motivation throughout our project. However, while <span class="highlighted">synthetic biology offers many new exciting possibilities</span>, several concerns have to be met when dealing with living organisms. Against, the excitement of the iGEM community, <span class="highlighted">skeptics have pointed to the uncertainty and potentiality for unwanted consequences</span> that might arise from working with synthetic biology. <span class="highlighted">We as a team decided to give these concerns some serious thought</span>! We have had several conversations on topics such as meta ethics, applied ethics, sustainability, GMO, and so on. Furthermore, we established an open and honest mode of discourse to use when engaging with other teams and the public. <span class="highlighted">We held a workshop in bioethics in relation to our Danish Meetup</span>. This workshop consisted of a historical insight into the history of GMO provided by our very own historian, as well as a hefty, kind-hearted debate, supervised by our own philosopher. |
+ | <br> | ||
+ | All of these considerations, <span class="highlighted">debates, and results led our philosopher Lene to write a longer guidebook entailing an overview of the various bioethical arguments often made for and against the use of synthetic biology</span>. The guidebook is mainly an insight into the most important ethical considerations made by our team, e.g. how they shaped our product, but it also offers a personal and clear overview of arguments and principles meant to help future teams to get a conversation on ethics started! | ||
+ | <br> | ||
+ | <span class="highlighted">Make sure to give this <a href="https://static.igem.org/mediawiki/2017/7/75/T--SDU-Denmark--guidebook.pdf" target="_blank">guidebook</a> a read</span>, it is definitely worth it!</p> | ||
</div></div> | </div></div> | ||
</div> | </div> | ||
Line 2,211: | Line 2,262: | ||
<div class="row border-left-practices"> | <div class="row border-left-practices"> | ||
<div class="col-xs-12"> | <div class="col-xs-12"> | ||
− | <h2><span class="highlighted">Integrated Practices</span></h2><hr> | + | <h2><span class="highlighted">Integrated Practices</span></h2><br><h4>- <i>An Implementation of the Future</i></h4><hr> |
− | <div style="text-align:center;"><p class="raleway P-Larger"><i>“The best way to predict your future, is to create it”</i></p><br><p class="raleway" | + | |
− | + | <div style="text-align:center; margin:35px 0 25px 0;"><p class="raleway P-Larger" style="text-align:center;"><i>“The best way to predict your future, is to create it”</i></p><br><p class="raleway">Abraham Lincoln - (former) president of the United States of America</p></div> | |
<br> | <br> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p>Not that we can claim to be anything like Abraham Lincoln, or even to be vampire hunters, | + | <p>Not that we can claim to be anything like Abraham Lincoln, or even to be vampire hunters. <span class="highlighted">Nonetheless, we do agree that to create the future we all hope for, we must contribute to find a sustainable solution for a greener future</span>. Before we can tackle the task of providing a sustainable future for the entire world, we must first look to our own local environment. <span class="highlighted">We believe that the best way to gain a better understanding of a global dilemma, is to examine how a local environment is affected by it. </span> Hopefully, this approach will help future iGEM teams find a connection between global issues and local ones. This approach has helped us elucidate specific issues and find sustainable solutions, which can be implemented into our society with the help and endorsement of local agents. </p> |
</div> | </div> | ||
− | |||
</div> | </div> | ||
Line 2,224: | Line 2,274: | ||
<p class="P-Larger"><b>A Statement from the Mayor of Odense</b></p> | <p class="P-Larger"><b>A Statement from the Mayor of Odense</b></p> | ||
− | <p>We first decided to reach out to the mayor of Odense, to investigate the possibilities for iGEM to help in the government's endeavours to make Odense a CO<sub>2</sub> neutral city | + | <p><span class="highlighted">We first decided to reach out to the mayor of Odense, to investigate the possibilities for iGEM to help in the government's endeavours to make Odense a CO<sub>2</sub> neutral city.</span></p> |
− | <p class="raleway citation"><i>“We face a series of challenges that we have to | + | <p class="raleway citation"><i>“We face a series of challenges that we have to recognise, in the chase of the good and sustainable life in the city of Odense. Some of these concern local circumstances, while others contain national and even global issues. We as the municipality can only go so far on our own. So, we are entirely dependent on the help of local agents. <span class="highlighted">It makes me so happy, when the students of the city, have taken on the mantle of developing new green technologies that solves global issues</span>, while contributing to local city growth”</i></p><br class="miniBreak"><p class="raleway citation-by"><a href="https://static.igem.org/mediawiki/2017/7/7e/T--SDU-Denmark--mail-mayor.pdf" target="_blank">Peter Rahbæk Juel</a> - Mayor of Odense</p> |
<br> | <br> | ||
− | <p>The core philosophy of our | + | <p><span class="highlighted">The core philosophy of our Integrated Human Practices has been to incorporate local experts in the development of our project.</span> We wanted to examine how results produced in the laboratory, could be used to shape a product that corresponds with the green values of Odense. <br> |
− | <br> | + | We sought the advice of experts in other fields, e.g. expert in plastics to design the best possible exterior of our device. Furthermore, we met with business developer Ann Zahle Andersen to investigate the core value of our product from a business perspective. <br> |
− | We | + | <span class="highlighted">We believe that Human Practices have played an essential role in our iGEM project. </span> Everything from the design of our prototype to ethical considerations have been influenced by the people we engaged with. |
</p> | </p> | ||
<br class="noContent"> | <br class="noContent"> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p class="P-Larger"><b> | + | <p class="P-Larger"><b>Interviewing Smart City Odense</b></p><br> |
− | <p>For the | + | <div><img class="interview-images" src="https://static.igem.org/mediawiki/2017/0/04/T--SDU-Denmark--kristina-dienhart.jpg"/><p style="display:inline;"><span class="highlighted">For the possible implementation of the PowerLeaf in the local environment of Odense, we decided to reach out to Kristina Dienhart, project manager of Smart City Odense.</span> Smart City Odense is a project within Odense Municipality, that seeks to combine urban planning with new technologies and open-data toward creating a smarter, more sustainable city. <br> |
− | <ul class="list"> | + | This made us aware of necessities essential to Odense and its citizens. She gave us feedback that we integrated into numerous areas of our overall project. |
− | <li>From Mrs. Dienhart’s point of view, one of the most advantageous attributes of our device | + | </p></div> |
− | + | <ul class="list" style="margin-top:15px;"> | |
− | + | <li><b>Changeability </b>- <span class="highlighted">From Mrs. Dienhart’s point of view, one of the most advantageous attributes of our device is the potential for changeability</span> in the size and shape of the design. We had yet to consider the PowerLeaf as a device not limited by physical dimensions. This has been the most significant element we took with us from the interview. Changeability is a necessity to a city planner, as various laws and aesthetic considerations need to be taken into account, when altering or creating an urban environment. </li> | |
− | + | <li><b>Accessibility </b>- She also discussed accessibility with us. <span class="highlighted">The citizen will not use our device unless it is easily accessible.</span> This means that the overall design of the PowerLeaf, regardless of its aesthetics, always needs to be designed with a user in mind. Reflecting on the advice of Mrs. Dienhart, <span class="highlighted">we decided to reevaluate the means of implementation of the PowerLeaf to ensure that the need for accessibility and user-comfort is met.</span></li> | |
+ | <li><b>Essentiality </b>- She supported our notion if the needs for <i>accessibility</i> and <i>changeability</i> are met, the PowerLeaf could help ensure that citizens of Odense use and remain in the public space for a longer amount of time. Something that is valuable, not only to the individual citizen, but also to the community as a whole, as it creates a sense of city cohesion and hence a high quality of city life. </li> | ||
</ul> | </ul> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p> | + | <p><span class="highlighted">Mrs. Dienhart introduced us to several considerations that shaped large parts of our project.</span> We do not know the needs of every urban area in Odense and consequently, we have aimed to create a device that is changeable to a city in movement such as Odense. |
<br> | <br> | ||
− | Furthermore | + | Furthermore, <span class="highlighted">this interview was also a source of inspiration for our ethical and safety thoughts.</span> While we <i>ought</i> to strive for a sustainable tomorrow, we do not necessarily have to provide an exhaustive description of what the future should look like. |
</p> | </p> | ||
<br class="noContent"> | <br class="noContent"> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p class="P-Larger"><b> | + | <p class="P-Larger"><b>Interviewing the City Renewal Project My Bolbro</b></p><br> |
<p> | <p> | ||
− | + | <div style="margin-top:-25px;"><img class="interview-images" src="https://static.igem.org/mediawiki/2017/b/b8/T--SDU-Denmark--rikke.jpg"/><p style="display:inline;"><span class="highlighted">Rikke Falgreen Mortensen is the manager of the Bolbro’s city renewal project called Mit Bolbro i.e. My Bolbro.</span> We arranged a meeting with her with the intent of further investigating how the PowerLeaf <i>could</i> and <i>should</i> be integrated in an urban area of Odense, in this case the neighbourhood of Bolbro.</p><br></div><p> | |
+ | Bolbro is an old neighbourhood in Odense historically known to be the home of the working class. While Bolbro provides a homely atmosphere known to the locals, it has had a hard time attracting new residents. However, <span class="highlighted">this is subject to change as the neighbourhood in 2016 received approximately 1.6 million US dollars to renew its city space</span> and to create an even more appealing, and vibrant neighbourhood. This will be achieved by including the locals, as Bolbro is characterized by having a strong, engaging civil society. Mrs. Mortensen is not only an expert in urban renewal, but also in how to include local citizens in reshaping the public space in which they reside. <br> | ||
+ | <span class="highlighted">Mrs. Mortensen also argued that a changeable design would be the optimal solution to fit the challenges one faces in creating a vibrant, green city ambience.</span> Such a task depends on different preferences, laws and needs. A technology needs to be both <i>flexible</i> and <i>accessible</i> to successfully contribute to the process of creating an engaging city environment. She showed great interest in our device and even offered to implement it in the parks of Bolbro, should the product become a reality.<p> We had a discussion with Mrs. Mortensen about the creation of a prototype based on the wishes of Bolbro’s local citizens. Following this conversation, she provided us with a <a href="https://static.igem.org/mediawiki/2017/4/4b/T--SDU-Denmark--mail-rikke.pdf" target="_blank">pitch</a> that aimed to help us develop this prototype.</p> | ||
+ | |||
+ | <p class="raleway citation"><i>“Hauge’s square is a spot in Bolbro, which we aim to make a central place in Bolbro; a place that invites the citizen to meet and dwell. <span class="highlighted">Your solution should be able to contribute to help citizens recharge their phones, e.g. a solution could be implanting the PowerLeaf into a interactive furniture, but where the demand an aesthetic pleasing design still remains.</span>”</i></p> | ||
<br> | <br> | ||
− | + | <div class="integrated-practices-prototypes"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/b/b7/T--SDU-Denmark--bench-human-practices.svg" type="image/svg+xml" style="width:100%;"></object></div> | |
<br> | <br> | ||
− | + | <p class="raleway citation"><i>“A part of the vision of this project is the concept of making a pop-up park with differently designed multi-furniture, preferably in wood and organic design, which are removable to the various areas where we are going to develop in the district. It is furniture that should be able to be used to relax in and at the same time also motivates children to move. <span class="highlighted">There is also a need for charging devices and it therefore demands that your solution is an integrated</span>, but still mobile solution, as the park will move physically over time.”</i></p> | |
− | + | ||
− | <p class="raleway citation"><i> | + | |
<br> | <br> | ||
<div class="integrated-practices-prototypes"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/f/f9/T--SDU-Denmark--powerleaf-integrated-bench.svg" type="image/svg+xml" style="width:100%;"></object></div> | <div class="integrated-practices-prototypes"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/f/f9/T--SDU-Denmark--powerleaf-integrated-bench.svg" type="image/svg+xml" style="width:100%;"></object></div> | ||
<br> | <br> | ||
− | <p class="raleway citation"><i> | + | <p class="raleway citation"><i>“Finally, the playground is to be developed especially for the young audience, which is a major consumer of power for phones. <span class="highlighted">The playground must be a place where youngsters hang out after school, while maintaining its status as a green space</span>.”</i></p> |
<br> | <br> | ||
<div class="integrated-practices-prototypes"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/f/f9/T--SDU-Denmark--powerleaf-integrated-bench.svg" type="image/svg+xml" style="width:100%;"></object></div> | <div class="integrated-practices-prototypes"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/f/f9/T--SDU-Denmark--powerleaf-integrated-bench.svg" type="image/svg+xml" style="width:100%;"></object></div> | ||
<br> | <br> | ||
− | + | <p>The making of the furniture as a prototype called for a revisit of our safety concerns. We now knew that children would be climbing and playing on the furniture, making it crucial that the material of the PowerLeaf will not break. This is a concern we discussed with Flemming Christiansen, which you can read all about next.</p> | |
− | + | ||
− | + | ||
− | + | ||
− | <p>The making of the furniture as a prototype called for a | + | |
<br class="noContent"> | <br class="noContent"> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p class="P-Larger"><b> | + | <p class="P-Larger"><b>Finding the Proper Material</b></p> |
<p><b>Criteria to the Prototype</b><br class="miniBreak"> | <p><b>Criteria to the Prototype</b><br class="miniBreak"> | ||
− | + | The system itself will consist of two different compartments, an outer and an inner chamber</span>. The first will be facing the sun, while the other will be facing the building or furniture. Since one culture of the bacteria depends on solar energy to produce its product, the outer compartment must allow for sunlight to pass. <span class="highlighted">It should here be noted that the prototype is purely hypothetical, as the membrane, between the two compartments, should exclusively be permeable to cellulose</span>. For that reason, we wanted to find a material, that fulfilled our established criteria, so that we could illustrate the technology. | |
− | + | The device itself will be made entirely from plastic, a material that is thought to be undesirable due to the difficulties in its disposal. This is due to plastic being of a xenobiotic nature, making it generally recalcitrant to microbial degradation<span class="reference"><span class="referencetext"><a target="blank" href=" https://ac.els-cdn.com/0167779988900844/1-s2.0-0167779988900844-main.pdf?_tid=f4188d40-be6e-11e7-916f-00000aacb35e&acdnat=1509477121_f4df2995d544bf9afdfe37f0e99577e2"> Fewson CA. Biodegradation of xenobiotic and other persistent compounds: the causes of recalcitrance. Cell. 1988.</a></span></span>. Following these concepts, we can identify the following set of criteria for the desired material:</p><br> | |
− | + | ||
<ul class="list"> | <ul class="list"> | ||
− | + | <li><b>Solar exposure.</b> The material covering the solar cell, must allow sunlight to pass through to reach the bacteria.</li> | |
− | + | <li><b>UV resistance.</b> <span class="highlighted">As the material will be exposed to the sun, it must be resistant to the UV radiation</span>.</li> | |
− | + | <li><b>Bacterial growth</b> The material must neither be growth inhibitory, nor toxic to the bacteria.</li> | |
− | + | <li><b>Easy to mold.</b> The outside of the device could be molded depending on the circumstances, as the device only relies on the bacterial technology.</li> | |
− | + | <li><b>Durability.</b> The device will be located outside, <span class="highlighted">meaning that the material must be able to withstand hard conditions and heavy weight</span>. </li> | |
− | + | <li><b>Temperature.</b> The material must allow for an appropriate constant temperature for the bacteria, despite the variations in sun exposure.</li> | |
− | + | <li><b>Longevity.</b> We would like for the material to have as long a durability as possible, since replacing the device could prove cumbersome. <span class="highlighted">We are aiming for at least twenty years of durability</span>. </li> | |
− | + | <li><b>Price.</b> We are looking for a material that is as cheap as possible, without sacrificing the necessary criteria.</li> | |
− | + | <li><b>Environmentally friendly.</b> <span class="highlighted">Considering the goal of this project being the creation of an environmentally friendly energy source, the ideal material would be as green as possible</span>. </li> | |
</ul> | </ul> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p><b>Interview with Flemming Christiansen</b><br class="noContent"> | + | <p><b>Interview with Flemming Christiansen</b></p><br class="noContent"> |
− | For the purpose of finding the necessary materials for our prototype, we contacted one of the leading plastic experts in Denmark, Flemming Christiansen, who acts as the market development manager of SP Moulding. He has been acting as a plastics consultant | + | <div><img class="interview-images" src="https://static.igem.org/mediawiki/2017/d/db/T--SDU-Denmark--flemming.jpg"/><p style="display:inline;">For the purpose of finding the necessary materials for our prototype, <span class="highlighted">we contacted one of the leading plastic experts in Denmark, Flemming Christiansen</span> , who acts as the market development manager of SP Moulding. He has been acting as a plastics consultant since his graduation as a master of science in Engineering, with a speciality in plastics. A meeting was quickly arranged for the purpose of confirming our criteria, the technical design, the material, and the possible price of creating the PowerLeaf. </p></div> |
<br> | <br> | ||
− | In accordance with our established criteria, | + | <p>In accordance with our established criteria, <span class="highlighted">Mr. Christiansen suggested that we use the plastic known as Polycarbonate, specifically Lexon 103R-III</span><span class=”reference”><span class="referencetext"><a target="blank" href="https://plastics.ulprospector.com/datasheet/e17532/lexan-103r-resin"> Polycarbonate</a></span></span>. Unfortunately, the material cannot fulfil the criteria on its own. He therefore suggested that we take a few liberties with it. In order to prevent UV degradation to the exposed parts, we will be adding certain additives to the surface. This increases the UV resistance of the device, without hindering the sunlight from reaching the bacteria. In accordance with our established criteria, <span class="highlighted">Mr. Christiansen suggested that we use the plastic known as Polycarbonate, specifically Lexon 103R-III</span><span class=”reference”><span class="referencetext"><a target="blank" href="https://plastics.ulprospector.com/datasheet/e17532/lexan-103r-resin"> Polycarbonate</a></span></span>. Unfortunately, the material cannot fulfil the criteria on its own. He therefore suggested that we take a few liberties with it. In order to prevent UV degradation to the exposed parts, we will be adding certain additives to the surface. This increases the UV resistance of the device, without hindering the sunlight from reaching the bacteria. |
+ | <br> | ||
+ | During our conversations with Mr. Christiansen, we reached the topic of what to do in case of a breach. Should the container against all expectations be damaged, the environment will be exposed to the GMO inside. The solution we came up with was the possible implementation of a kill-switch in the inner compartment, making it vulnerable to sunlight. Should the bacteria of said unit be exposed to sunlight, they would perish. <span class="highlighted">As the outer compartment would be dependent on the continued coexistence of the two units, the entire GMO system would be purged in case of a breach</span> . To implement this feature, the inner chamber would be covered with Carbon Black, which has the ability to absorb sunlight, thus leaving the compartment itself in darkness. <br> | ||
+ | The process of constructing our device would be through an extensive use of Injection Moulding, which is considered pricey equipment. The material is expensive at 4-5.5 USD per kg at orders above 1 metric ton, according to Mr. Christiansen, but its longevity and durability means it would not need to be replaced for a long time. Lastly, we discussed the reusability of Polycarbonate, which he assured us was of no concern, as the material could be <i>reused</i> and <i>recycled</i> with ease. | ||
+ | </p><br> | ||
+ | <div class="integrated-practices-prototypes"><object class="highlighted-image" data="https://static.igem.org/mediawiki/2017/f/f9/T--SDU-Denmark--powerleaf-integrated-bench.svg" type="image/svg+xml" style="width:100%;"></object></div> | ||
<br> | <br> | ||
− | |||
− | |||
<br class="noContent"> | <br class="noContent"> | ||
<br class="noContent"> | <br class="noContent"> | ||
− | <p class="P-Larger"><b> | + | <p class="P-Larger"><b>Workshop with Business Developer Ann Zahle Andersen</b></p><br> |
− | <p> | + | <div><img class="interview-images" src="https://static.igem.org/mediawiki/2017/a/af/T--SDU-Denmark--ann-zahle.jpg"/><p style="display:inline;">For the purpose of getting a business perspective on our project, we met with Business Developer Ann Zahle Andersen. She arranged two workshops for us based on a business model canvas. She encouraged us to view our project, as if we meant to make startup business. <span class="highlighted">These workshops gave us a better comprehension of society’s pull and pushes on a project like ours</span>. This forced us as a team to get to the bottom of what we found important about our project.</p></div> |
<br class="noContent"> | <br class="noContent"> | ||
<br class="noContent"> | <br class="noContent"> | ||
<p class="P-Larger"><b>Upcoming Meeting with Borgernes Hus</b></p><br> | <p class="P-Larger"><b>Upcoming Meeting with Borgernes Hus</b></p><br> | ||
− | <p> | + | <p>Borgernes Hus i.e. House of the Citizens is a new initiative offered by the City Central Library. The initiative aims to offer guidance and advice to projects such as ours. It is meant to aid Odense in its journey towards the status of becoming a modern Danish city. Unfortunately, the building remains under construction until after our trip to Boston, meaning that they have been busy with the construction while our project was underway. <span class="highlighted">It is for this reason that we, along with director Jens Winther Bang Petersen, agreed that a future collaboration would be the most suitable solution.</span> |
<br> | <br> | ||
− | It is our hope, that a collaboration with Borgernes Hus will be of assistance to future iGEM | + | It is our hope, that a collaboration with Borgernes Hus will be of assistance to future iGEM teams from SDU as well as other students from Odense. |
</p> | </p> | ||
Line 2,332: | Line 2,383: | ||
<div class="row border-left-practices"> | <div class="row border-left-practices"> | ||
<div class="col-xs-12"> | <div class="col-xs-12"> | ||
− | <h2><span class="highlighted">Education & Public Engagement</span></h2><hr> | + | <h2><span class="highlighted">Education & Public Engagement</span></h2><br><h4>- <i>A Philosopher’s Guide to the Future</i></h4><hr> |
− | <p></p> | + | <p><i>If you want change, look to the future!</i> Such was the wording of our core philosophy. A philosophy that was carried out, by <span class="highlighted">reaching out to the people of our society to ensure the engagement of the next generation, within the world of synthetic biology.</span></p> |
</div> | </div> | ||
− | + | ||
</div> | </div> | ||
<div class="row"><div class="col-xs-12"> | <div class="row"><div class="col-xs-12"> | ||
+ | <p class="P-Larger"><b><span class=”highlighted”>Danish Science Festival</b></span></p><br class=”miniBreak”> | ||
+ | <p><span class="highlighted">At the Danish Science Festival we hosted a workshop for kindergarteners</span>, during which we taught them about <span class="highlighted">synthetic biology, sustainability, the history of GMO, and bioethics.</span> The children would in turn teach us as well, as they showed us the endless possibilities for bacteria designs, through <span class="highlighted">the “Draw-a-Bacteria”-contest.</span> This <a href="#inspiration-from-children" target="_blank">inspired</a> us to reevaluate our initial idea.</p><br> | ||
− | < | + | <img /> |
− | <p> | + | <p class="P-Larger"><b><span class=”highlighted”>School Project Interview with 6<sup>th</sup> Graders</b></span></p><br class=”miniBreak”> |
+ | <p>Following the Danish Science Festival, we were contacted by two enthusiastic 6<sup>th</sup> graders, Bastian and Magnus. The two boys wanted to learn more about iGEM and GMO, which they intended to write about in a school project. They were curious to what range GMO could be used, and how we utilised it in our project, the PowerLeaf.</p><br> | ||
− | + | <p>insert image</p> | |
− | + | ||
− | |||
− | <!-- | + | <p class="P-Larger"><b><span class=”highlighted”>UNF Summer Camp</b></span></p><br class=”miniBreak”> |
+ | <p>The UNF Summer Camp is an opportunity for high school students to show extra dedication towards science. We talked to some of the brightest young minds imaginable, all of whom aim to work in different fields of science in the future. <span class="highlighted">At the summer camp, we held a presentation about our project, the iGEM competition, as well as how to handle and work with genes. | ||
+ | We taught them how to assemble BioBricks and provided them with BioBricks for DNA assembly experiments, creating a ‘hands-on’ experience for these enthusiastic teenagers.</span> | ||
+ | <br> | ||
+ | One of the high school students suggested that the Powerleaf should be able to rotate according to the sun, to ensure maximum exposure and outcome. We took this brilliant advice into consideration and contacted Robot Systems Engineer student, Oliver Klinggaard, who helped us with the potential implementation of a pan/tilt system. He provided us with his recent project report on the subject, as well as a description of the adjustments required for the implementation in our system, which you can find [Bilag pdf]here[Bilag pdf] | ||
+ | <br> | ||
+ | Two students from the UNF Summer Camp thought the PowerLeaf was an interesting approach to sustainable energy, and they wanted to hear even more! So, they contacted us in late October, as they were interested to work on a project about green technology.</p><br> | ||
+ | |||
+ | <p>insert image</p> | ||
+ | |||
+ | <p class="P-Larger"><b><span class=”highlighted”>The Academy for Talented Youth</b></span></p><br class=”miniBreak”> | ||
+ | <p><span class="highlighted">We hosted a workshop for the Academy for Talented Youth, an association for some of the most talented high school students in Denmark.</span> During the workshop we invited the students into our laboratories, where they conducted a miniprep and a gel electrophoresis on bacteria containing our BioBricks. Additionally, we held a presentation and discussion about our project, with the dedicated students. We strongly believe in mutual communication and made sure to compile feedback, all of which was positive! </p><br> | ||
+ | |||
+ | |||
+ | <p>insert image</p> | ||
+ | |||
+ | |||
+ | <p class="P-Larger"><b><span class=”highlighted”>Presentations for the Local Schools</b></span></p><br class=”miniBreak”> | ||
+ | <p><span class="highlighted">The local high schools, Mulernes Legatskole and Odense Tekniske Gymnasium, invited us to present our project, in addition to starting discussions with the students about GMO.</span> <br> | ||
+ | <span class="highlighted">An 8<sup>th</sup> grade class from the local public school, Odense Friskole, were invited to see our laboratory workspace.</span> It was a challenge to successfully convey our project and the concept of synthetic biology in a way that would be easily understandable by 8<sup>th</sup> graders, who have only recently been introduced to science. A challenge that we accepted and solved, by relaying the fundamentals in synthetic biology, e.g. the basics of a cell, DNA, and GMO. | ||
+ | <br> | ||
+ | <span class="highlighted">From all of these presentations and interactions with younger individuals, we had a strong intuition that it had made an influence on their awareness of synthetic biology. This intuition was supported by the positive feedback provided by teachers and students.</span> An awareness of how new scientific technologies can be a feasible solution to a possible energy crisis. Technologies such as synthetic biology, with endless capabilities to achieve efficacy, since no one knows what tomorrow brings. For more information about this read <a class="nav-item nav-link active" href="#future-igem-teams">To Future iGEM Teams</a></p><br> | ||
+ | |||
+ | |||
+ | <p class="P-Larger"><b><span class=”highlighted”>Final Presentation at SDU-Denmark</b></span></p><br class=”miniBreak”> | ||
+ | <p><span class="highlighted">The day before we travelled to Boston, we booked one of the big auditoriums at the University of Southern Denmark, for the final rehearsal of our jamboree presentation.</span> We made sure to take note of all the feedback and tips we received, while also implementing these into our final presentation. This event was promoted on all the information screens at our university in order to attract a broad audience and increase the interest for iGEM. Thus, making it possible to reach a substantial amount of future applications for the SDU-iGEM team and <span class="highlighted">ensure that the iGEM spirit will continue to prosper in the future!</span> </p><br> | ||
+ | |||
+ | |||
+ | <p class="P-Larger"><b><span class=”highlighted”>Social Media</b></span></p><br class=”miniBreak”> | ||
+ | <p>Social media is an easy way to impact a high number of people, so a strategy was concocted with the intention of reaching as many people as possible with our outreach. | ||
+ | <span class="highlighted">Our strategy yielded marvellous results, amongst which was a video on our project, that reached viewers equal to 16% of our hometown’s population, along with becoming the second most seen bulletin of the year from University of Southern Denmark.</span> They have also asked us to film our experiences at the Jamboree, which will feature on the homepage of the student’ initiative BetonTV. | ||
+ | <span class="highlighted">Several articles were written about our project in local newspapers, one was even featured in the saturday special.</span><span class="btn-link btn-lg" data-toggle="modal" data-target="#about-social-media">You can read all about our social media strategy and results here.</span>The commercial can be seen right here.</p> | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
</div></div> | </div></div> | ||
</div> | </div> | ||
Line 2,477: | Line 2,554: | ||
Employed by the energy converting unit, this system degrades cellulose to glucose, from which electrons could be retrieved. After extensive work the system showed promising results as our bacteria were able to grow on cellobiose. If you are interested, you can read more about the work we did regarding the <a href="#project-design-cellulose-breakdown">cellulases</a>.</li><br class="noContent"> | Employed by the energy converting unit, this system degrades cellulose to glucose, from which electrons could be retrieved. After extensive work the system showed promising results as our bacteria were able to grow on cellobiose. If you are interested, you can read more about the work we did regarding the <a href="#project-design-cellulose-breakdown">cellulases</a>.</li><br class="noContent"> | ||
<li><span class="highlighted"><b>Extracellular Electron Transfer</b></span><br class="miniBreak"> | <li><span class="highlighted"><b>Extracellular Electron Transfer</b></span><br class="miniBreak"> | ||
− | Inspired by a previous study <span class= | + | Inspired by a previous study<span class=”reference”><span class="referencetext"><a target="blank" href="http://mbio.asm.org/content/8/1/e02203-16.full"> Tan Y, Adhikari RY, Malvankar NS, Ward JE, Woodard TL, Nevin KP, et al. Expressing the Geobacter metallireducens pilA in Geobacter sulfurreducens Yields Pili with Exceptional Conductivity. mBio. 2017;8(1).</a></span></span>, we set out to create the required BioBricks for the system. However, to successfully implement optimized nanowire in <i>G. sulfurreducens</i>, further work would have to be performed. If you are interested, you can find additional information about the work we did regarding the <a href="#project-design-extracellular-electron-transfer">nanowires</a>.</li> |
</ul> | </ul> | ||
<br class="noContent"> | <br class="noContent"> | ||
Line 2,530: | Line 2,607: | ||
<div class="col-md-8 col-xs-10 margin-bottom-200 margin-top-50"> | <div class="col-md-8 col-xs-10 margin-bottom-200 margin-top-50"> | ||
− | <div style="text-align:center;"><p class="raleway P-Larger"><i>“You'll stay with me?”</i> - <i>“Until the very end”</i></p><br><p class="raleway"><i>J.K. Rowling, Harry Potter and the Deathly Hallows</i></p></div><br><br class="noContent"> | + | <div style="text-align:center;"><p class="raleway P-Larger"><i>“You'll stay with me?”</i> - <i>“Until the very end”</i></p><br><p class="raleway" style="text-align:center;"><i>J.K. Rowling, Harry Potter and the Deathly Hallows</i></p></div><br><br class="noContent"> |
<p><span class="largeFirstLetter">J</span>ust like in the movies, you only get to meet the brilliant minds behind the project in the closing credits. Some might leave the cinema without sitting through the credits, but we hope you will sit through ours, as you will get to know us on a more personal level. We probably have more in common than you think. And do not forget that <span class="highlighted">behind every great team is an equally great amount of external <a href="#attributions" target="_blank">attributions</a></span>. The contributors have supported and inspired us, especially when things have been rough and deadlines closeby. <span class="highlighted">When you finish this section, we kindly ask that you turn your attention to our various <a href="#collaborations" target="_blank">collaborations</a></span>, all of which have been amazing experiences. They truly show of that wonderful iGEM spirit! | <p><span class="largeFirstLetter">J</span>ust like in the movies, you only get to meet the brilliant minds behind the project in the closing credits. Some might leave the cinema without sitting through the credits, but we hope you will sit through ours, as you will get to know us on a more personal level. We probably have more in common than you think. And do not forget that <span class="highlighted">behind every great team is an equally great amount of external <a href="#attributions" target="_blank">attributions</a></span>. The contributors have supported and inspired us, especially when things have been rough and deadlines closeby. <span class="highlighted">When you finish this section, we kindly ask that you turn your attention to our various <a href="#collaborations" target="_blank">collaborations</a></span>, all of which have been amazing experiences. They truly show of that wonderful iGEM spirit! | ||
<br> | <br> | ||
− | Finally, | + | Finally, <span class="highlighted"> we do not want you to miss out on the ‘after-the-credits-clip’ that summarises the fun we had during this fantastic iGEM adventure.</span> This is will be the moment you will get that long-awaited ‘thank you for listening, we hope you enjoyed our wiki and project’. |
</p> | </p> | ||
</div> | </div> | ||
Line 2,849: | Line 2,926: | ||
<li>Stud.scient, <span class="highlighted"><strong>Birka Jensen</strong></span>, for general advice and suggestion on how to build an iGEM wiki.</li> | <li>Stud.scient, <span class="highlighted"><strong>Birka Jensen</strong></span>, for general advice and suggestion on how to build an iGEM wiki.</li> | ||
<li>Stud.med, <span class="highlighted"><strong>Ida Charlotte Hvam</strong></span>, for helpful discussions on the development of our wiki, helping with last minute figures to the wiki, as well as proofreading its content.</li> | <li>Stud.med, <span class="highlighted"><strong>Ida Charlotte Hvam</strong></span>, for helpful discussions on the development of our wiki, helping with last minute figures to the wiki, as well as proofreading its content.</li> | ||
+ | <li>Stud.med, <span class="highlighted"><strong>Maria Victoria Mikkelsen</strong></span>, for helpful guidance regarding the composition of experiment pages and proofreading.</li> | ||
+ | <li>Stud.med, <span class="highlighted"><strong>Liza Gaardsted Hansen</strong></span>, for proofreading our wiki in the 11<sup>th</sup> hour.</li> | ||
<li>Ph.D student and current iGEM advisor for the Bielefeld team, <span class="highlighted"><strong>Boas Pucker</strong></span>, for providing us with BioBricks created by former iGEM teams from Bielefeld.</li> | <li>Ph.D student and current iGEM advisor for the Bielefeld team, <span class="highlighted"><strong>Boas Pucker</strong></span>, for providing us with BioBricks created by former iGEM teams from Bielefeld.</li> | ||
<li>Our iGEM HQ Representative, <span class="highlighted"><strong>Traci Haddock-Angelli</strong></span>, for her general guidance and assistance in registering our Danish Ethics and Wiki Workshop to the official iGEM meetup page.</li> | <li>Our iGEM HQ Representative, <span class="highlighted"><strong>Traci Haddock-Angelli</strong></span>, for her general guidance and assistance in registering our Danish Ethics and Wiki Workshop to the official iGEM meetup page.</li> | ||
Line 2,887: | Line 2,966: | ||
<li><span class="highlighted"><strong>PentaBase</strong></span>, for sponsoring us with 10,000 DKK worth of oligos and a further 10% discount.</li> | <li><span class="highlighted"><strong>PentaBase</strong></span>, for sponsoring us with 10,000 DKK worth of oligos and a further 10% discount.</li> | ||
<li><span class="highlighted"><strong>New England Biolabs</strong></span>, for providing our team with a BioBrick® Assembly Kit, a Q5® High-Fidelity 2X Master Mix and a Quick-Load® Purple 2-Log DNA Ladder.</li> | <li><span class="highlighted"><strong>New England Biolabs</strong></span>, for providing our team with a BioBrick® Assembly Kit, a Q5® High-Fidelity 2X Master Mix and a Quick-Load® Purple 2-Log DNA Ladder.</li> | ||
− | <li><span class="highlighted"><strong>CO<sub>2</sub> | + | <li><span class="highlighted"><strong>CO<sub>2</sub> Neutral Website</strong></span>, for attributing to green energy in our name, and thereby eliminating the carbon footprint our wiki makes.</li> |
<li><span class="highlighted"><strong>Piktochart</strong></span>, for extending their student offer to our mail, and for providing us with easy access to great graphics.</li> | <li><span class="highlighted"><strong>Piktochart</strong></span>, for extending their student offer to our mail, and for providing us with easy access to great graphics.</li> | ||
</ul> | </ul> | ||
Line 2,930: | Line 3,009: | ||
<p> Vestergaard P, Rejnmark L, Mosekilde L. Osteoporosis is markedly underdiagnosed: a nationwide study from Denmark. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2005;16(2):134-41.</p> | <p> Vestergaard P, Rejnmark L, Mosekilde L. Osteoporosis is markedly underdiagnosed: a nationwide study from Denmark. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2005;16(2):134-41.</p> | ||
<p> Vestergaard P, Rejnmark L, Mosekilde L. Osteoporosis is markedly underdiagnosed: a nationwide study from Denmark. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2005;16(2):134-41.</p> | <p> Vestergaard P, Rejnmark L, Mosekilde L. Osteoporosis is markedly underdiagnosed: a nationwide study from Denmark. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2005;16(2):134-41.</p> | ||
− | + | <p>Administration USDoEEI. Method for Calculating Carbon Sequestration by Trees in Urban and Suburban Settings. 1988. | |
+ | <br> | ||
+ | Alper T, Gillies NE. The relationship between growth and survival after irradiation of Escherichia coli strain B and two resistant mutants. Journal of general microbiology. 1960;22:113-28. | ||
+ | <br> | ||
+ | Andreas M. Kaplan MH. The Britney Spears universe: Social media and viral marketing at its best. Business Horizons. 2012. | ||
+ | <br> | ||
+ | Anna Prusak GR, Jacek Strojny. IS GMO “SUSTAINABLE”? A REVIEW OF THE ENVIRONMENTAL RISKS OF GM PLANTS IN COMPARISON WITH CONVENTIONAL AND ORGANIC CROPS. MODERN MANAGEMENT REVIEW. 2004. | ||
+ | Arai TM, S. Cho, H. Y. Yukawa, H. Inui, M. Wong, S. L. Doi, R. Synthesis of Clostridium cellulovorans minicellulosomes by intercellular complementation. Proceedings of the National Academy of Sciences of the United States of America. 2007;104(5):1456-60.</p> | ||
</div> | </div> | ||
<div class="col-md-1"></div> | <div class="col-md-1"></div> |
Revision as of 16:14, 1 November 2017