Genetics screens to identify new genes involved in caenorhabditis elegans vulval tissue.

C. elegans is a hermaphrodite which uses an Epidermal Growth Factor Receptor (EGFR) IRAS pathway to regulate cell fates and vulval differentiation. The let-23 gene encodes a C. elegans homolog ofEGF-R necessary for vulval development. Mutations in lin-1 can cause a multi vulva or a non-vulval phenotype, while mutations in let-23 or lin-2 result in the reduction of the number of vulval cells. Animals homozygous for mutations· both let-23 and lin-2 make no vulval tissue. EMS mutagenesis was used to screen for new mutations, which would suppress the vulval defect of the doubly mutant let-23, lin-2 animals. L4s were picked and their offspring were screened for new mutations that restored egg-laying abilities. After extensive screens, it seems only lin-1 was found, which is a previously characterized ETS protein. Thus, it seems that no other genes act at this late step in the process