Studies of transvection and chromatin in Drosophila melanogaster

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9511808 Wu Several candidate members of a putative chromatin complex have been identified in Drosophila. These include the products of zeste, Posterior sex combs, Suppressor 2 of zeste, Polycomb, Polycomb-like, and polyhomeotic). Genetic, biochemical, and cytological data argue for the existence of other members as well as for other types of complexes. Who are the other members? What other complexes are there and who are the members of the other complexes? These are important questions because the impact of a complex is the sum of the activities of all its members and it is not possible to fathom a complex until all its components are understood. This proposal address these questions. Genetic screens to find chromatin-related genes have relied almost exclusively on four phenomena: PFV, zeste1 eye color, homeosis, and dosage compensation. Clearly, these phenomena fall short of representing the full range of developmental programs. As a consequence, our understanding of the proteins and mechanisms by which chromatin regulates gene expression is limited and it is almost certain that more chromatin-related proteins and processes remain to be discovered. For example, of the 12-17 proteins thought to participate in one species of chromatin complex, less than half have been identified. The goal of the proposal is, therefore, to identify the chromatin-related genes and mechanisms that have managed thus far to elude researchers. The strategy of the proposed research is to diversify the genetic approach by implementing three new kinds of screens for genes encoding chromatin-related functions. Our screens are unlike most, if not all, previous screens which identified genes by mutations that modified specific phenotypes, such as eye color or segment identity. Instead, our screens will identify genes by virtue of their interaction or redundancy with some of our best candidates for chromatin proteins. %%% Chromatin structure underlies phenomena as fundamental as inheritance and gene expressio n. It is involved in transcription, position effects, recombination, and oncogenesis, to mention just a few examples. This proposal explores the structure of chromatin in Drosophila. ***