Individual Antennapedia and Bithorax complex homeobox genes in Drosophila have the remarkable property of speciying the identity of entire segments of the larva during development. Current evidence indicates that these genes encode transcription factors. Although a great deal is known about the structure and regulation of the two homeobox genes complexes, the next tier of genes, "downstream" genes, regulated by the homeotics have not been identified. The PI's laboratory has characterized "enhancer trap" transposon insertions in Drosophila whose expression of LacZ is now regulated by the homeotic gene Antennapedia (Antp) in imaginal discs. These newly acquired instances of regulation by Antp are presumably due to adjacent enhancer sequences. The isolation and characterization of these sequences which are normally regulated by Antp will allow for the generation of detailed patterns of expression of genes normally expressed later in the developemnt of the imaginal discs and which are under the control of Antp. These studies should aid in understanding how the regulatory mechaninms for establishing patterns are connected to cell differentiation as it occurs during morphogenesis.
