The synthetic activity and glandular volume of the corpus allatum during ovarian maturation in the desert locust [formula omitted

Abstract

We have compared, on an individual basis, the volume of the corpora allata with their ability to synthesize and release juvenile hormone (JH) using glands taken at daily intervals throughout the period of sexual maturation and the first two ovarian cycles in Schistocerca gregaria . A standard in vitro radiochemical assay was used to measure the rates of both spontaneous JH biosynthesis from [methyl- 14C]-methionine, and of JH biosynthesis stimulated by optimal concentrations of [C-2 3H]-farnesenic acid. Computation of results showed that there are, during this period, changes of up to 250-fold in the rate of spontaneous JH biosynthesis per unit volume corpora allata. It is concluded that the volume of the corpora allata is of no value as an indicator of the spontaneous synthetic activity of the glands in this species, and that the overall rate of JH synthesis is regulated by mechanisms that do not involve large changes in the volume of the gland cells. However, in the presence of farnesenic acid, there is a corelation between stimulated JH synthesis and glandular volume, suggesting that the volume of the gland reflects the maximum activity of the final two stages in JH biosynthesis.