On the competence of corpora allata to synthesise juvenile hormone and the dependence of their activity on haemolymph factors in the cockroach, Nauphoeta cinerea

Abstract

By using a long-term in vitro system whereby corpora allata (CA) are incubated in a mixture of haemolymph and medium containing [ 14C]methionine, we were able to demonstrate that rates of JH III biosynthesis are strongly dependent on haemolymph factors as well as the intrinsic competence of the CA. High rates of synthesis were observed in media containing haemolymph of viteloogenic and pregnant females and low rates in media containing haemolymph of previtellogenic, chorion-forming and ovulating females. In media containing haemolymph of vitellogenic females rates of synthesis decreased with time in the case of CA from stages around the vitellogenesis peak, and increased in the case of CA from previtellogenic and early vitellogenic stages. CA from ovulating females could not be activated and those of males maintained a low and constant level of activity. The addition of JH III in vitro stimulated the incorporation of labelled methionine in a dose-dependent manner but not of labelled acetate.