The Effect of Natural Solar UV Radiation on the G1 Checkpoint in S. pombe

Overview

Objectives/Goals The purpose of my project is to test whether natural solar UV radiation is energetic enough to damage DNA to the point where cell cycle checkpoints are required. Methods/Materials I took advantage of the fact that caffeine is known to override cell cycle checkpoints, allowing cells to divide with damaged DNA. If the damage is great enough, death will occur. I grew the fission yeast Schizosaccharomyces pombe in liquid YES medium. I then exposed diluted cultures cells to natural solar UV radiation in Whirlpack bags (control dark, control light, 10 mM caffeine light, 10 mM caffeine dark) to allow damage the DNA in the yeast cells. I took 10 µL subsamples throughout the day and plated them on agar. I incubated the plates for two days at 36ºC and saw that there was a gradation in the presence of colonies throughout the day. No growth represented the cells that died because the caffeine overrode their checkpoints when the DNA was damaged. I did this on Aug 27, 2011. To model annual variation in solar UV damage, I took light readings at different times of the year and compared them to my readings taken during the survival experiments. Results My results showed that different amounts of UV do have an effect on the cell growth, as shown clearly with the caffeine-treated cells. Conclusions/Discussion From this I conclude that natural solar UV radiation is strong enough to damage the DNA and the checkpoints are needed to make sure that DNA is not replicated when it is damaged.

Competition history

• CSEF 2012 Biochemistry/ Molecular Biology · Entry S0524

Resources

• CSEF project summary ↗

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