Meeting Abstract

P3.208  Tuesday, Jan. 6  Membrane remodeling, glucose and Drosophila melanogaster cold tolerance: A test of chilling injury protection hypotheses. MACMILLAN, Heath/A*; SINCLAIR, Brent/J; University of Western Ontario; University of Western Ontario hmacmil2@uwo.ca

Insect cold tolerance varies at both the population and species levels. Carbohydrate cryoprotectants and membrane remodelling are two main mechanisms hypothesised to increase chilling tolerance in Drosophila melanogaster, as part of both long-term (ie: evolutionary) change and rapid cold-hardening (RCH), which can take place in minutes to hours. We used cold-selected lines of D. melanogaster with and without a pre-exposure that induces RCH to test three hypotheses: 1) that increased cold tolerance would be associated with increased free glucose; 2) that increased cold tolerance would be associated with desaturation of membrane phospholipid fatty acids and 3) that increased cold tolerance would be associated with a change in phospholipid head group composition. We used colourimetric assays to measure free glucose and a combination of thin layer chromatography-flame ionization detection and gas chromatography to measure membrane composition. We observed a consistent decrease in free glucose with RCH, and no relationship between free glucose and basal cold tolerance. Also, phospholipid head group ratios and fatty acid composition showed no change following an RCH treatment. Thus, we conclude that changes in free glucose and membrane composition are unlikely to be significant determinants of variation in cold tolerance of D. melanogaster.