67.6 Sunday, Jan. 6 Cryoprotective Dehydration and Inoculative Freezing in the Antarctic Midge, Belgica antarctica ELNITSKY, M.A.*; HAYWARD, S.A.L.; RINEHART, J.P.; DENLINGER, D.L.; LEE, R.E.; Miami University; Liverpool University; Ohio State University; Ohio State University; Miami University email@example.com
During winter, larvae of the Antarctic midge, Belgica antarctica, must endure 7-8 months of continuous subzero temperatures, encasement in a matrix of soil and ice, and severely desiccating conditions. This environment, along with the fact that larvae possess a high rate of water loss and are extremely tolerant of desiccation, may promote the use of cryoprotective dehydration as a strategy for winter survival. This study investigates the capacity of larvae to resist inoculative freezing and undergo cryoprotective dehydration at subzero temperatures. Slow cooling to -3oC in an environment at equilibrium with the vapor pressure of ice reduced larval water content by ~40% and depressed the body fluid melting point more than 3-fold to -2.6oC. This melting point depression was the result of the concentration of existing solutes and the de novo synthesis of osmolytes. At day fourteen of the subzero exposure, larval survival was >95%, suggesting larvae have the capacity to undergo cryoprotective dehydration. The ability of larvae to resist inoculative freezing and utilize a strategy of cryoprotective dehydration was significantly affected by soil moisture content. As detected by a reduction of larval water content, the percentage of larvae that resisted inoculative freezing increased with decreasing soil moisture. These results suggest that larvae of the Antarctic midge have the capacity to resist inoculative freezing at relatively low soil moisture contents and likely undergo cryoprotective dehydration during the polar winter.