Two groups of fruit flies ( Drosophila melanogaster
) were maintained on different diets. Mitochondria were isolated, proton leak was measured and phospholipid fatty acid composition determined. Mitochondria from flies fed on corn-base meal (containing high amounts of polyunsaturated fatty acids, 18:2(n
-6) and 18:3(n
-3) and low amounts of monounsaturated fatty acid, 18:1(n
-9)) contained more polyunsaturated fatty acids in their membranes than mitochondria from flies fed on yeast-base meal (containing less amount of polyunsaturates and high amount of monounsaturates). The more polyunsaturated mitochondria were leakier to protons than the more monounsaturated mitochondria.