Changes in membrane lipid composition following rapid cold hardening in Drosophila melanogaster

• Published in: Journal of insect physiology Vol. 51; no. 11; pp. 1173 - 1182
• Main Authors: Overgaard, Johannes, Sørensen, Jesper G., Petersen, Søren O., Loeschcke, Volker, Holmstrup, Martin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2005
• Subjects: acclimation; Acclimatization; Animals; cell membranes; Circadian Rhythm; cold acclimation; Cold selection; cold stress; Cold Temperature; cold tolerance; Drosophila melanogaster; Drosophila melanogaster - chemistry; Drosophila melanogaster - physiology; Drosophila Proteins - biosynthesis; Drosophila Proteins - genetics; fatty acid composition; Fatty Acids - chemistry; Female; Gene Expression; heat shock protein 70; heat shock proteins; Hsp70; HSP70 Heat-Shock Proteins - biosynthesis; HSP70 Heat-Shock Proteins - genetics; lipid composition; Male; Membrane Lipids - chemistry; Membrane Lipids - physiology; Phospholipid composition; phospholipid fatty acids; phospholipids; Phospholipids - chemistry; Polyunsaturated fatty acids; protein synthesis; Rapid cold hardening; selection response; Time Factors; Cold selection; Rapid cold hardening; Hsp70; Phospholipid composition; Polyunsaturated fatty acids
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2005.06.007

Naturally occurring diurnal variations in temperature are sufficient to induce a rapid cold hardening (RCH) response in insects. RCH can increase cold tolerance by 1–2 °C and extend the temperature interval at which insects can remain active. While the benefits of RCH are well established, the underlying physiological mechanisms remain unresolved. In this study we investigated the role of RCH on expression of heat shock proteins (Hsp70) after a cold shock, and the effect of RCH on the composition of phospholipid fatty acids (PLFAs) in membranes of Drosophila melanogaster. These experiments were performed on both “control” flies and flies selected for cold resistance in order to additionally examine a possible target for selection for cold tolerance. RCH improved survival following cold shock at −4, −6 and −8 °C. No induction of Hsp70 was found following cold shock irrespective of the pre-treatment. In contrast, a 5 h RCH treatment was sufficient to induce small, but significant, changes in the composition of PLFAs. Here, the polyunsaturated linoleic acid, 18:2( n−6), increased while monounsaturated (18:1) and saturated (14:0) PLFAs decreased in abundance. These changes were observed in both selection groups and caused a significant increase in the overall degree of unsaturation. This response is consistent with the membrane response typically found during cold acclimation in ectothermic animals and it is likely adaptive to maintain membrane function during cold. Cold selection resulted in PLFA changes (decrease of 18:0 and 18:1 and increase of 14:0 and 16:1), which may improve the ability to harden during RCH.