Developmental regulation of juvenile hormone biosynthesis by the ring gland ofDrosophila melanogaster

Summary The synthesis in vitro of the putative dipteran juvenile hormone (JHB₃) by ring glands isolated from third instarDrosophila melanogaster larvae was quantified by a radiochemical assay. The data indicate that JHB₃ synthesis is developmentally regulated during the period prior to wandering until after puparium formation. The highest level of basal production occurred during the postfeeding stage, and synthesis declined after pupariation. Similar relative profiles of synthesis were obtained upon the addition of the JHB₃ precursor, farnesoic acid, although the absolute levels of production were elevated considerably. Basal JHB₃ production by brain-ring gland complexes in vitro was also highest during the postfeeding stage, although the synthetic rates were much lower than displayed by isolated ring glands. Further analysis revealed that methyl farnesoate, a JHB₃ precursor, was synthesized by brain-ring gland complexes in significant quantity. A dual mechanism of brain-centered control of JHB₃ biosynthesis is proposed.To whom offprint requests should be sent