Team:Stanford-Brown/HellCell/Radiation

Radiation

Assay
Liquid cultures of NEB5α E. coli transformed with mntH, recA, sod Cu/Zn, dps, and negative control were grown up over night at 37oC. The following day, the cells were washed and resuspended in 0.9% NaCl solution. Cell concentration was then adjusted to 10^7/mL in 5mL of a glass Petri dish. Each sample was then exposed to 1.2 J/(m^2*sec) of UV-C radiation from a UV lamp for a cumulative of 0 seconds, 2 seconds, 5 seconds, 10 seconds, 20 seconds, and 30 seconds. After each exposure, a dilution spot assay was conducted to determine the final number of surviving cells.

Figure 1: Displays survival of negative control, mntH construct, recA construct, sod Cu/Zn construct, and dps construct transformed E. coli after specific dosages of UV-C radiation.

Conclusions

The results of assaying constructs which convey radiation resistance seem to indicate that there may be one part that is successful. In Figure 1, it can be clearly seen that E. coli transformed with the dps construct tend to survive at higher percentages at a given UV-C dosage. 10% survivability is witnessed in all constructs other than dps at levels lower than 5 J/m^2; however, these results seem to indicate that dps may have 10% survivability at levels as high as 10 J/m^2. In this assay, only one replicate of each sample was able to be assayed; however, future assays have given conflicting and inconsistent results. For example, further assays seem to display an inconsistency in survivability and UV-C dosage. Thus, although this assay may indicate that the dps construct conveys radiation resistance, further and more accurate assays need to be conducted in order to reach a definitive conclusion.