Very long-chain fatty acids change the ethanol tolerance of Drosophila melanogaster larvae

This research tested the hypothesis that long-chain saturated fatty acids increase the order of cell membranes of an organism and minimize the detrimental fluidizing effects of ethanol. Unsaturated fatty acids increase membrane fluidity and are unlikely to increase the ethanol tolerance of the organism. Both a fatty acid-free medium and media supplemented with very long-chain fatty acids (20 or more carbons) were fed to wild-type larvae of Drosophila melanogaster; larvae were then transferred to media with or without ethanol to test for effects of the fatty acids on ethanol tolerance. Ethanol decreased the percent of larvae to pupate, and lengthened larval development time. However, the percentage of pupae to reach the adult stage and the weight of adult males increased when the larvae were fed ethanol. The very long-chain, unsaturated fatty acids, arachidonic acid [20:4(n-6)] and docosatetraenoic acid [22:4(n-6)], were associated with increased larval mortality when administered in a medium supplemented with ethanol. Arachidic acid (20:0) increased the percentage of larvae to pupate under ethanol stress, decreased the development time and increased the adult weight in the presence and absence of ethanol. Behenic acid (22:0) was not effectively incorporated into phospholipids and had little effect on growth traits. Thus, the experimental results were consistent with the hypothesis.