Transcriptional control of developmental processes by ecdysone inDrosophila virilis salivary glands.

Injection of α-ecdysone into the larval haemolymph of late third instar larvae ofD. virilis induces both the extrusion of secretory proteins and the inactivation of the enzyme glutamine-fructose-6-phosphate-aminotransferase (E.C. 2.6.16) in the salivary glands. In the presence of actinomycin D or cycloheximide the hormone is ineffective. If before adding these inhibitors RNA synthesis is allowed to proceed for 1.5h, or protein synthesis for 2h after ecdysone injection, however, the protein extrusion and the enzyme inactivation do occur. It is proposed that ecdysone controls these two cytoplasmic events at the transcriptional level by the activation of specific Correlations with puff activities are discussed.