Membrane remodeling and glucose in Drosophila melanogaster: A test of rapid cold-hardening and chilling tolerance hypotheses

• Published in: Journal of insect physiology Vol. 55; no. 3; pp. 243 - 249
• Main Authors: MacMillan, Heath A., Guglielmo, Christopher G., Sinclair, Brent J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2009
• Subjects: Acclimatization - physiology; Animals; cell membranes; Chill tolerance; Cold selection; cold stress; Cold Temperature; cold tolerance; cryoprotectants; Drosophila melanogaster; Drosophila melanogaster - chemistry; Drosophila melanogaster - physiology; fatty acid composition; fatty acid desaturation; Fatty acids; Fatty Acids - analysis; glucose; Glucose - analysis; Linear Models; lines; Membranes - chemistry; Phospholipid composition; phospholipids; Phospholipids - analysis; Phospholipids - chemistry; Rapid cold-hardening; selection response; Cold selection; Chill tolerance; Phospholipid composition; Fatty acids; Rapid cold-hardening
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2008.11.015

Insect cold tolerance varies at both the population and species levels. Carbohydrate cryoprotectants and membrane remodeling are two main mechanisms hypothesised to increase chilling tolerance in Drosophila melanogaster, as part of both long-term (i.e., evolutionary) change and rapid cold-hardening (RCH). 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.