P3.205 Sunday, Jan. 6 Genetic mechanisms of cold tolerance through increased desiccation resistance in Drosophila melanogaster KOBEY, R.L.*; GASSERT, R.; MONTOOTH, K.L.; Indiana University; Indiana University; Indiana University email@example.com
We have previously identified complex patterns of cold survival in Drosophila melanogaster across genotypes and temperatures that suggest distinct physiological causes for cold mortality across low temperatures. Supporting this interpretation, we found that desiccation contributes to mortality for milder cold exposures (6ºC) but not at lower temperatures (-4ºC). Flies were dehydrated following potentially lethal exposures at 6ºC but were not dehydrated following -4ºC exposures. Additionally, survival increased with humidity at 6ºC but not at -4ºC. We have begun to investigate candidate genes that may mediate differences in cold tolerance through differences in desiccation resistance. In many insects, exposure to either cold or desiccation induces expression of heat shock proteins such as Hsp70. This suggests that Hsp70 expression may increase cold survival by increasing desiccation resistance. To test this hypothesis, we are measuring survival and Hsp70 expression of mutants with differing Hsp70 copy number at low humidity and at cold temperatures. We have found that genotypes with more copies of Hsp70 tend to have higher desiccation resistance than genotypes with fewer copies of Hsp70. However, the pattern appears to be different for survival at 6ºC. Understanding the reason for this difference will further our investigation of the physiological-genetic mechanisms that mediate differences in cold tolerance among populations of D. melanogaster.