LONG-CHAIN FATTY-ACIDS AND ETHANOL AFFECT THE PROPERTIES OF MEMBRANESIN DROSOPHILA-MELANOGASTER LARVAE

The larval fatty acid composition of neutral lipids and membrane lipid s was determined in three ethanol-tolerant strains of Drosophila melan ogaster. Dietary ethanol promoted a decrease in long-chain fatty acids in neutral lipids along with enhanced alcohol dehydrogenase (EC 1.1.1 .1) activity in all of the strains. Dietary ethanol also increased the incorporation of C-14-ethanol into fatty acid ethyl esters (FAEE) by two- to threefold and decreased the incorporation of C-14-ethanol into free fatty acids (FFA). When cultured on sterile, defined media with stearic acid at 0 to 5 mM, stearic acid decreased ADH activity up to 3 3%. In strains not selected for superior tolerance to ethanol, dietary ethanol promoted a loss of long-chain fatty acids in membrane lipids. The loss of long-chain fatty acids in membranes was strongly correlat ed with increased fluidity in hydrophobic domains of mitochondrial mem branes as determined by electron spin resonance and correlated with a loss of ethanol tolerance. In the ethanol-tolerant E2 strain, which ha d been exposed to ethanol for many generations, dietary ethanol failed to promote a loss of long-chain fatty acids in membrane lipids.