Team:WashU StLouis/Description

For the last century as a consequence of industrialization, greenhouse gas emissions have depleted the ozone layer, especially at the Earth's poles. One function of the ozone layer is to absorb UV radiation emitted by the sun, protecting life on Earth from its harmful effects on DNA. When exposed to UV, DNA tends to form pyrimidine dimers which interfere with DNA replication and translation and can lead to mutations and cell death. While many focus their attention on the effects of UV radiation on humans, photosynthetic organisms must also be considered because they are responsible for the world's oxygen and form the basis for nearly all food chains. Though many photosynthetic organisms already have UV repair mechanisms, it is becoming increasingly necessary to fortify and supplement these mechanisms because of the drastic increase of UV exposure within the last century.

In order to protect against increased levels of UV-B radiation, our team turned to an extremely radiotolerant species of tardigrade, R. varioenatus. Known for its ability to survive in even the most extreme of environments, this strangely adorable microorganism has several genes that encode resistance to the dangers of UV irradiation. We see this as having two major applications: (1) the production of UV-resistant cyanobacteria which could replace current wild-type cyanobacteria in order to halt the cycle of ozone depletion; and (2) improving the efficiency of cyanobacteria-focused biofuel production. We then created BioBrick-compatible genetic constructs from two of these genes and expressed them in E. coli and cyanobacteria as a proof-of-concept.

Throughout our work over the summer we accomplished a number of important tasks towards realizing the goals we set forth in our plan. First, we were able to confirm that the Dsup gene taken from R. varioenatus does in fact protect against UV radiation. Through the testing of our genetic constructs with the Dsup gene, we produced data to support that Dsup protects against UV-B radiation and also illustrated the significant change in UV-B resistance that can be given to E. Coli cells and potentially cyanobacteria. We also created a new piece of hardware - the Environmental Simulation System - which functions as a tabletop incubation chamber capable of exposing cells to UV-B radiation in both liquid cultures and plated cells.