Specification of male development in Caenorhabditis elegans: the fem genes

Mutation of the gene fem-2 causes feminization of both sexes: hermaphrodites make no sperm, and males produce oocytes in an intersexual somatic gonad. A double mutant harboring ts alleles of both fem-1 (formerly named isx-1; G. A. Nelson, K. K. Lew, and S. Ward, 1978, Dev. Biol. 66, 386-409) and fem-2 causes transformation of XO animals (normally male) into spermless hermaphrodites at restrictive temperature. The phenotypes, temperature-sensitive periods, and maternal effects observed in mutants of each fem gene are found to be similar. It is suggested that the fem genes are centrally involved in specification of male development in Caenorhabditis elegans--both in the germ line of hermaphrodites and in somatic and germ line tissues of males.