Team:UCopenhagen/InterLab
Introduction
We participated in InterLitab, as we want to be contribute to the scientific progress made through this globe spanning project. In InterLab, 6 test devices are inserted in E.coli D5 α, and the growth and fluorescence is measured.
We used the following plasmids provided by iGEM HQ to transform E.coli:
- Positive control
- Negative control
- Test Device 1: J23101+I13504
- Test Device 2: J23106+I13504
- Test Device 3: J23117+I13504
- Test Device 4: J23101.BCD2.E0040.B0015
- Test Device 5: J23106.BCD2.E0040.B0015
- Test Device 6: J23117.BCD2.E0040.B0015
Calibrations
Before our measurements began, we performed some calibrations: First an OD600 reference point for our plate reader, performed with LUDOX according to the protocol. Here we found a correction factor which can be used to calculate OD from measured absorbance. Our correction fator is 3.11.
Secondly we made a fluorescence standard curve with a serial dilution of fluorescein (figure 1). We used the lower 5 data points to calculate a mean µM fluorescein pr a.u. We chose to use the lower concentration range due to two factors: 1) Linearity is better for the lower fluorescein concentrations, and 2) our measured data has a maximum fluorescence of 500, which makes it more important to have a good fit in the lower range.
Cell measurements
Two colonies from each transformation were picked, and grown in foil-covered 50 ml falcon tubes over night (18 hours).
Preparation OD was measured, and a dilution was calculated to achieve an OD of 0.02. Dilution calculations can be found in the table next to this. Here we used the calculated correction factor from our initial abs/OD calibration. From the absorption measurements taken at 0 hours, we see indications of pipetting errors, as the OD600 (average) ranges from 0.015 to 0.6 (table 1).
Introduction
Our team believes that establishing a stable platform for scientists to create naïve orthogonal living compartments, would allow for an unpredictable advancement in the field of synthetic biology. Our project will not attempt to create an endosymbiont, but instead investigate the mechanisms in free-living cells in a bottom-up approach to endosymbiosis.
Therefore, we decided to work on three distinct, but intertwined, projects pertaining to endosymbiosis, namely Interdependence, Number Control, and Protein import. We believe that by combining these three projects, a key step towards the understanding of endosymbiosis and its employment in synthetic biology will be obtained.
Sub-projects:
Cell growth stagnated between 4 and 6 hours. Cells transformed with Test Device 1 and 4 grew slower than the 6 other transformations, and even decreased in OD between 4 and 6 hours. Click on figures for enlarged images:
OD600
Cell growth stagnated between 4 and 6 hours. Cells transformed with Test Device 1 and 4 grew slower than the 6 other transformations, and even decreased in OD between 4 and 6 hours. Click on figures for enlarged images:
Fluorescence
Some transformed cells continue to increase fluorescence despite a decrease in OD in the same samples. Devices 3 and 6 are very close to the negative control in fluorescence. Click on figures for enlarged images:
Conclusion
Our data indicate which plasmid elements induce the highest production of GFP.
Plasmids containing J23117 (Test devices 3 and 6) does not express fluorescence to a higher degree than the negative control. Plasmids with J23101 (Device 1 and 4) induced the highest fluorescence, and plasmids containing J23106 (Test devices 2 and 5) were somewhere in between. Combining the J23101 or J23106 with I13504 (Test devices 1-3) gave a higher fluorescence than adding BCD2.E0040.B0015 (Test devices 4-6).
These results are not reliable on their own, but will be more robust and reliable when combined with data from the other teams participating in the interlab study.
