Fig. 4.
Regulation of the reproductive/diapause status of the insect gut. Under LD conditions, which favor reproduction (Left), the corpora allata (CA) secrete JH in response to signals from the pars intercerebralis (PI) of the brain. In the gut, JH acts through its receptor Met, Clk, and Cyc to stimulate expression of Pdp1iso1 and other genes that characterize the reproductive state, whereas expression of cry2 and diapause downstream genes is suppressed. Although the regulation involves circadian clock genes, it is independent of daily oscillations of the circadian gene expression. In the absence of endogenous JH under short photoperiod (Right), expression of cry2 prevails over Pdp1iso1, favoring the diapause-specific program. By acting through Met, Clk, and Cyc, exogenous JH mimic can induce the reproductive program under SD condition.