The project is focused on studies of gene expression during development in Drosophila melanogaster. Mutations of the white locus, which encodes a product that has strong sequence similarity with ATP-binding membrane transport proteins including the product of the cystic fibrosis gene of humans, show a wide range of changes in expression and regulation. We have concentrated on a group that originated by insertion of the transposon BEL into the 5' region of the gene. The original mutant strain and its derivatives show unusual regulatory changes in white expression; all have partial repression of gene expression when coupled with zeste mutations, a locus encoding a transcription factor. The zeste mutations also exhibit a trans effect on normal white locus function by repressing expression of paired wild-type alleles. Our results suggest that the transcription factor encoded by zeste functions in establishing and stabilizing the expression of white locus by binding DNA and modifying chromatin conformation. Another developmentally regulated locus being studied is echinus, a gene that plays a role in development of facets in the adult eye. The gene has been cloned and the molecular characterization is being done. A cDNA library from eye imaginal disc tissue has been probed to recover clones of the coding sequence for the protein product.
