The Roles of Segmentation Gene Homologues in Annelids

Williams College, Williamstown MA

Investigators

Abstract

0090378 Savage Current understandings of cell differentiation and pattern formation in animals have largely been based on data obtained from 'model' systems such as the fruit fly Drosophila melanogastor. The extent to which developmental mechanisms operating in the fly are conserved in other phyla is at present unknown. This question will be addressed by examining annelid homologues of fly developmental regulatory genes and their role in the diversification of body plans. In all animals that have been studied to date, the Hox gene cluster is responsible for determining regional identity along the anterior-posterior body axis. The upstream regulation of this gene cluster points to a potential source of morphological variation between body plans. Knowledge of Hox gene regulation beyond Drosophila is limited. Therefore, the specific aim is to identify in annelids homologues to fly genes which have been shown to regulate Hox gene expression. The homologues to two Drosophila segmentation genes, hunchback and caudal , in both leeches and in polychaetes will be characterized. This comparative approach will allow us to differentiate between general developmental mechanisms and phylum-specific ones, in so doing providing novel insights into the formation and regional specification of the annelid embryo.