The aim of the proposed research is a better understanding of how inductive events function in the development of a multicellular organism. This work will focus on genetic and molecular analysis of factors that interact with the product of the C.elegans gen glp-1 (for germ line proliferation). This gene encodes a transmembrane protein that functions in the development of two major tissues in C.elegans; the germ line and the anterior pharynx. I propose to use two molecular approaches to identify genes that specifically interact with the conserved intracellular portion of glp-1. This domain of the protein contains the conserved repeats homologous to the cell cycle an tissue differentiation genes in many organisms. The first method will employ a yeast genetic system that allows selection for physically interacting proteins. The other method relies on construction of labeled fusion proteins to directly probe C.elegans expression libraries. C.elegans is an excellent system for this type of study because once clones are identified they can be analyzed using the genetics of the organism. In a genetic screen I will use one of the many well characterized mutant alleles of glp-1 to look for enhancers of weak glp-1 phenotypes. In this way I hope to obtain a better understanding of not only C.elegans development but of the role of cell-cell interactions in general.