Insects have been widely used as model systems to study basic mechanisms of hormone production and action. Study of the regulation of hormone production in insects by key regulatory proteins holds promise in the development of new biorational pesticides. Recent work on one major group of regulatory proteins (allatostatins) demonstrates that they are found in many species, but that they vary considerably in function (and hence in potential practical utility). Such work emphasizes that insects are a large and diverse group, with a long evolutionary history and diversity in regulation of reproduction. The general objective of this proposal is to understand the basis of reproduction in an insect that is strategically situated on the evolutionary tree to provide connections between major insect groups (and hence regulatory features that may be broadly applicable). This investigation will utilize the ring-legged earwig, Euborellia annulipes. This insect is an excellent model system for investigating the regulation of egg development because it exhibits precisely timed cycles of ovarian development and cycles of juvenile hormone production that are highly correlated with the reproductive cycle.
Our recent work suggests that earwigs have allatostatins (inhibitors of juvenile hormone production) and that earwig allatostatins differ from those isolated thus far from other insect species. In preliminary studies we found that extract of brain tissue of earwigs suppresses juvenile hormone production by earwig corpora allata in vitro indicating the presence of an earwig brain allatostatin and providing a bioassay (test) for its isolation and identification. The goals are to (1) isolate and characterize earwig allatostatins, using sequential chromatographic fractionation in combination with an in vitro bioassay for juvenile hormone synthesis to identify the inhibitory fractions (s). following amino acid sequence analysis, we will determine the degree of similarity (if any) to other neuropeptides. If earwig allatostatins are unique, we will (2) generate antibody probes for use in localization and quantitation of these substances within the nervous system. These inter-related goals capitalize on existing chemical isolation procedures, bioassays, and immunochemistry, and exploit the history of earwigs exploration of the evolution of insect hormone biosynthesis. Regulation and function.
