The effects of nutritional deficiencies on themaroon-likematernal effect in Drosophila

Abstract

1. Themaroon-likematernal effect, present whenma-lflies are bred from non-mutant mothers, is not found among the late emergents from normal cultures. The hypothesis that this is due to a deficiency of some nutrient(s) in old cultures is tested by growing larvae on defined, germ-free media with the nutrients reduced one at a time.2. Omission of lecithin (but not reduction of casein, sucrose, RNA or cholesterol) decreases the percentage of maternally affected emergents, in proportion to the lowering of the lecithin supply. This is not a consequence of choline deficiency but of the shortage of fatty acids. Oleic, palmitic and linoleic acids can substitute for lecithin, when adequate choline is provided.3. Pantothenic acid, nicotinic acid, thiamine and biotin deficiencies (but not reduced pyridoxine, riboflavine or folic acid) also lower the proportion of maternally affected flies. There is an interaction between pantothenic acid and lecithin, but not between lecithin and the other effective vitamin deficiencies.4. Addition of the excretory product hypoxanthine to the complete diet significantly lowers the proportion of maternally affected emergents, but equivalent amounts of uric acid, or of guanylic acid, do not. It is argued that the quantitive relationships make it improbable that accumulation of excretory products play any great part in the disappearance of the maternal effect, whereas it is more likely that nutritional deficiencies do.5.ma-llarvae grown on low lecithin have the same complement of xanthine dehydrogenase as those reared on normal lecithin. The lecithin effect is therefore assumed to operate by affecting the pattern of pteridine synthesis. Phenylalanine, which would also be expected to alter this pattern, modifies the maternal effect similarly.