Molecular Genetics of Segment Determination in Drosophila

Molecular genetics will be used to investigate how complex biological structures are constructed in the fruit fly, Drosophila melanogaster. The development of Drosophila proceeds via a hierarchy of gene expression which, in its early stages, generates segmented embryo. Following segmentation, each metamere develops a particular identity due to the action of the homeotic selector genes. The products of these genes all contain the DNA-binding homeodomain and probably function by transcriptionally regulating a set of target genes. To understand how homeotic selector genes specify particular metameric identities it is important to isolate and study these target genes. They will be isolated by using a subtractive hybridization procedure designed to identify differences in gene expression between animals that overexpress a particular homeotic selector gene (Ultrabithorax, Ubx) and animals that underexpress this gene. Once isolated, we will rank our interest in these genes by answering the following questions: Do their patterns of expression correlate with Ubx expression in wild type animals? Do their patterns of expression change in animals mutant for homeotic selector genes (including, but not limited to, Ubx mutations)? And, do any of these genes map to positions in the genome where Ubx proteins bind or to where known homeotic loci are located? We will focus on those genes that fulfill most of these criteria. They will be further characterized both molecularly and genetically to determine how they function during development to generate metameric identities.***//