Mutations in a number of genes in the fruit fly lead to an overproduction of neuronal precursor cells. One such gene, "pecanex", is expressed maternally and codes for a large, transmembrane protein thought to be involved in cell interactions occurring early in neurogenesis. The discovery of homology between "pecanex" in the fruit fly and an expressed gene in rat suggests that the study of this gene in the fruit fly may be relevant to understanding neurogenesis in vertebrates. Immunocytochemistry and in situ hybridization will be used to study the expression of the "pecanex" gene and its gene product in the fruit fly embryo. In addition, molecular techniques will be used to define the coding region of the "pecanex" gene. The principal investigator teaches at a small undergraduate college and will be training young scientists in neurogenetics during the course of these studies.