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

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.