Complex regulation of
fem-3 must occur so that it can direct male development in the proper tissues(1,2). The
fem-3 gene product must be active in the XO soma to direct male development and active in the XO germ line to direct spermatogenesis. In contrast,
fem-3 must be inactive in the XX soma to allow female development and transiently active in the hermaphrodite germ line to allow a brief period of spermatogenesis. Both maternal and zygotic
fem-3 activity are required for these processes. The
fem-3 gene has been cloned(3) and its predicted protein sequence is novel. The identification of
fem-3(1f) mutations supports our prediction of the putative open reading frame and argues that the null phenotype offem-3 is complete feminization of XX and XO animals. We have analysed the regulation of
fem-3 RNA in order to understand how
fem-3 activity is modulated to direct male development. The following results suggest translational and/or post- translational regulation is important for the control offem-3 activity: (1) Early embryos contain predominantly matemalfem-3 RNA consistent withfem-3 maternal effects. Because much of this RNA is degraded before the 9 cell stage, we predict it is translated during the first few cell divisions. (2) XX and XO embryos show no differences in the accumulation or degradation of maternalfem-3 RNA indicating sex specific regulation of embryonicfem-3 activity must be post-transcriptional. We predict that either the distribution of
fem-3 protein is different in XX and XO embryos or embryonic
fem-3 activity is controlled post-translationally. (3) During development, the polyadenylation of
fem-3 RNA is regulated: poly A tails are longest in embryos, are intermediate in length during larval stages and are shortest in adults. Because inappropriate
fem-3 activity in
fem-3(gf) mutants is correlated with an intermediate length poly A tail (see abstract, Ahringer and Kimble), we predict
fem-3 is translated in all stages of the wild type hermaphrodite except in adults. We have made antibodies to bacterially expressed
fem-3 protein which will be used to test these predictions.