Control of juvenile hormone biosynthesis during the reproductive cycle of a viviparous cockroach: I. Activation and inhibition of corpora allata

Abstract

An in vitro radiochemical assay has been used to determine the juvenile hormone (JH) synthetic capacity of denervated and transplanted corpora allata (CA) of female Diploptera punctata. CA maintained in vitro over a 24-hr period do not increase their rate of JH synthesis whether taken from females in which they would undergo a dramatic increase in vivo (just before vitellogenesis) or from females in which CA synthesize JH at a low rate for an extended period (as in pregnancy). However, when CA are denervated and allowed to remain in vivo, a normal cycle of JH synthesis is observed in mated females. In virgin females, which do not normally mature eggs, the denervation mimics mating in that the CA undergo a synthetic cycle and oocytes are matured. Denervation of CA of young pregnant females (16% gestation) does not result in an immediate cycle of synthesis similar to that of mated females, nor do 0-day CA transplanted to allatectomized pregnant females exhibit such a cycle. However, inactive CA from the pregnant females transplanted to allatectomized 0-day animals promptly undergo a cycle of JH synthesis with an associated maturation of oocytes. From these results it is concluded that the integrity of the nerves of CA is required for inhibition of synthetic activity, whereas some factor in the hemolymph, not present in pregnant females, is responsible for activation and maintenance of the JH synthetic cycle.