3':5'-cyclic AMP and hormonal control of puparium formation in the fleshfly Sarcophaga bullata.

Abstract

Injection of 3'':5''-cyclic cAMP into larvae of the fly S. bullata 3-4 h before the beginning of puparium formation (red-spiracle stage) greatly accelerates the onset of tanning without affecting initiation of puparium formation (anterior retraction). Accelerated tanning resembles real tanning in 2 important respects: the solubility of cuticular proteins becomes reduced and [U-14C]tyrosine is incorporated into the cuticle. Of a number of cAMP analogues tested, 3'':5''-cGMP, 2'':3''-cAMP, and 5''-AMP were inactive, dibutyryl-3'':5''-cAMP had only slight activity, and cIMP and deoxy-3'':5''-cAMP showed some activity. Theophylline enhanced the effect of small doses of cAMP or of blood, diluted 1:8, active in the puparium tanning factor. Injection of dopa, dopamine, acetyldopamine or epinephrine, but not of tyrosine, had an accelerating effect similar to that of cAMP. The tanning-inhibiting effect of DL-.alpha.-methyl-.alpha.-hydrazino-.beta.-(3,4-dihydroxyphenyl)propionic acid monohydrate is reversed by dopamine or epinephrine, but not by tyrosine, dopa or cAMP. Evidence is presented to indicate that the responses to cAMP are not artifacts but reflect actual biochemical events during tanning.