9506237 Perrimon A detailed analysis of genes critical for early events in cellular determination is one of the best approaches to the understanding of the mechanics of early development. Embryonic development in Drosophila requires both maternal and zygotic gene products. To identify genes that control specific embryonic patterning events, maternal functions have been detected via mutations isolated from screens for female sterility, while zygotic functions which are masked by the maternally stored gene product and loci with specific maternal effect lethal phenotypes which are associated with pre- imaginal lethality cannot be identified using these two approaches. To characterize the function of such loci Dr. Perrimon has previously successfully used germline mosaic techniques. These analyses, which were limited to the X-chromosome for technical reasons, identified a large number of new genes that play critical roles during embryonic development. The goal of this proposal is to conduct near saturation screens for all zygotic lethal mutations located on the second and third chromosomes (80% of the genome) that are associated with specific maternal effect lethal phenotypes. These experiments will provide a complete description of the kinds of processes controlled by the maternal activity of essential genes. In addition, they will provide the foundation for further detailed analyses of various patterning systems that operate during embryogenesis. Dr. Perrimon's laboratory will focus on the characterization of new terminal class genes. In addition, since these screens will generate a large collection of additional mutations with interesting phenotypes, the collection of mutants will be made available to the fly community. The wealth of information generated from these studies will contribute to our general understanding of the mechanisms underlying embryonic pattern formation in Drosophila and will identify the genetic functions encoded by the Drosophila genome . ***
