Ecdysterone induced protein synthesis in salivary glands and in fat body of Drosophila melanogaster larvae.

Salivary glands of 3rd instar larvae of Drosophila melanogaster were labeled with 3H-leucine in the presence and absence of ecdysterone. Twenty-six ecdysterone inducible proteins were detected. Their induction was correlated with puff stage. Synthesis of fifteen proteins commenced during early puff stage (PS2); synthesis of seven others at late puff stages (PS8-10). Synthesis of four proteins was induced between puff stage 3/4 and 7/8. Thus, the hormonal induction of protein synthesis generally reflected the appearance of early and of late puffs as described by Ashburner (1972). Eleven ecdysterone inducible proteins were detected in larval fat body in vitro. Comparison of the fat body to the salivary gland proteins revealed that one of the ecdysterone induced fat body proteins was identical in molecular weight and charge to one of the proteins induced by ecdysterone in salivary glands.