Monitoring Editor: Marianne Bronner-Fraser The Deleted in Azoospermia (DAZ) gene family encodes putative translational activators that are required for meiosis and other aspects of gametogenesis in animals. The single C. elegans homologue of DAZ,
daz-1, is an essential factor for female meiosis. Here we show that
daz-1 is important for the switch from spermatogenesis to oogenesis (the sperm/oocyte switch), which is an essential step for the hermaphrodite germline to produce oocytes. RNA interference of the
daz-1 orthologue in a related nemetode C. briggsae resulted in a complete loss of the sperm/oocyte switch. The C. elegans hermaphrodite deficient in
daz-1 also revealed a failure in the sperm/oocyte switch if the genetic background was conditional Mog (masculinization of germline). DAZ-1 could bind specifically to mRNAs encoding the FBF proteins, which are translational regulators for the sperm/oocyte switch and germ stem cell proliferation. Expression of the FBF proteins seemed to be lowered in the
daz-1 mutant at the stage for the sperm/oocyte switch. Conversely, a mutation in
gld-3, a gene that functionally counteracts FBF, could partially restore oogenesis in the
daz-1 mutant. Taken together, we propose that
daz-1 plays a role upstream of the pathway for germ cell sex determination.