ego-1 gene function is required for normal germline development and, consequently, for fertility (1, 2). In addition to its pleiotropic germline phenotype,
ego-1 is also required for a robust response to RNAi by many germline-expressed genes (2). EGO-1 protein is a member of the RNA-directed RNA polymerase (RdRP) family, whose other members include N. crassa QDE-1, A. thaliana SGS-2, and tomato RdRP. These proteins have been implicated in RNA silencing phenomena, as well. Consistent with these results,
ego-1 appears to be expressed mainly, if not entirely, in the germ line (2). We are studying
ego-1 to understand better its role in development and if/how its developmental role is related to its role in RNAi. We are carrying out a variety of studies aimed at describing the EGO-1 expression pattern in the gonad and identifying potential targets of EGO-1 regulation. For comparison with other RNAi-defective mutants (Rde and Mut genes), we are examining whether transgenes are desilenced in the
ego-1 mutant germ line, and whether Rde mutations enhance the Ego-1 developmental phenotype. The results of these ongoing studies will be presented. (1) Qiao, L., Lissemore, J.L., Shu, P., Smardon, A., Gelber, M.B., and Maine, E.M. (1995) Genetics 141:551-569. (2) Smardon, A., Spoerke, J.M., Stacey, S.C., Klein, M.E., Mackin, N., and Maine, E.M. (2000) Current Biology 10:169-178.