Juvenile hormone: The status of "Status Quo"

Abstract

SYNOPSIS. Cuticular proteins show specificity for stage, age, and anatomical region. Analysis of the cuticular proteins of second pupae created by application of juvenile hormone demonstrates that the hormone prevents the onset of new sequences of syntheses and favors repetition of the region-specific, temporal pattern of syntheses used in the previous stage. The argument made is that juvenile hormone might exert this "status quo" action by preventing alterations in chromatin configuration. Evidence from a wide variety of systems shows that polyamines might be involved in reprogramming chromatin. Ecdysterone induces ornithine decarboxylase, the rate limiting enzyme in animal polyamine synthesis. I suggest that juvenile hormone might be exerting its status quo action by inhibiting this induction. Preliminary studies of ornithine decarboxylase induction support this specific hypothesis; experiments with an inhibitor of this enzyme, α-difluoromethyl ornithine, however, do not show the expected juvenile hormone mimicry. Further studies are needed to define the control of polyamine biosynthesis in insects and to discover whether juvenile hormone plays a role in this control. © 1981 by the American Society of Zoologists.