1. A reduction in the dietary concentration of
choline, an essential nutrient for Drosophila melanogaster, from the optimal concentration of 80 micrograms/ml of defined medium to 8 micrograms/ml diminished the level of tissue
phosphatidylcholine to less than one-third the normal level in third instar larvae without significantly altering the amount of
phosphatidylethanolamine. 2. The rates of synthesis of
phospholipids,
triglycerides,
diglycerides and
monoglycerides were reduced by the
choline-deficiency, and the chain length of
fatty acids in
lipids was shortened. 3. The activity of
succinic dehydrogenase, a mitochondrial
enzyme, was decreased by the deficiency, but the activities of
fumarase, sn-glycerol-3-phosphate
dehydrogenase, alcohol dehydrogenase, sn-glycerol-3-phosphate
oxidase and
fatty acid synthetase were unaffected. A
choline-deficiency did not alter the ultrastructure of mitochondria of larval fat body cells. 4.
Choline-deficient individuals were more susceptible to the toxic effects of
ethanol during larval and pupal development, and less adept at utilizing
ethanol as a substrate for adult tissue synthesis.