Characterization of seven genes affecting Caenorhabditis elegans hindgut development

We have identified and characterized 12 mutations in seven genes that affec t the development of the Caenorhabditis elegans hindgut. We find that the m utations can disrupt the postembryonic development of the male-specific bla st cells within the hindgut, the hindgut morphology in both males and herma phrodites, and in some cases, the expression of a hindgut marker in hermaph rodite animals. Mutations in several of the genes also affect viability. On the basis of their mutant phenotypes, we propose that the genes fall into four distinct classes: (1) egl-5 is required for regional identity of the t ail; (2) sem-4 is required for a variety of ectodermal and mesodermal cell types, including cells in the hindgut; (3) two genes, lin-49 and lin-59, af fect development of many cells, including hindgut; and (4) three genes, mab -9, egl-38, and lin-48, are required for patterning fates within the hindgu t, making certain hindgut cells different from others. We also describe a n ew allele of the Pax gene egl-38 that is temperature sensitive and affects the conserved beta-hairpin of the EGL-38 paired domain. Our results suggest that a combination of different factors contribute to normal C. elegans hi ndgut development.