Role of ecdysone, pupariation factors, and cyclic AMP in formation and tanning of the puparium of the fleshfly Sarcophaga bullata

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Abstract
Two pupariation factors, anterior retraction factor (ARF) and puparium tanning factor (PTF), are absent from the hemolymph of [S. bullata] larvae at the time of tanning accelerated by ARF/PTF, cyclic[c]AMP or dopamine. ARF and PTF are not involved in derepression of dopa decarboxylase (aromatic L-amino-acid decarboxylase, aromatic L-amino-acid carboxy-lyase, EC 4.1.1.28) synthesis initiated by ecdysone. Tanning is entirely inhibited by injection of 2 transcriptional inhibitors, actinomycin and BrdUrd [5-bromodeoxyuridine] and 2 translational inhibitors, puromycin and cycloheximide. Retraction activity is more severely inhibited by the transcriptional than by the translational inhibitors. A tanning response is initiated by cAMP in the presence of the transcriptional but not the translational inhibitors. Dihydric tanning substances (dopa, dopamine) initiate tanning in the presence of both types of inhibitors. Release of ARF and PTF from the CNS is inhibited by the 4 inhibitors. ARF totally reverses the inhibitory effects on retraction, whereas PTF does not reverse inhibition of tanning. These data are interpreted to mean that PTF is concerned with the regulation of 2 components of the tanning response: acceleration of synthesis of a particular protein (associated with the tyrosine hydroxylation complex) and activation via cAMP of a component of the tyrosine hydroxylating system.