A zebrafish nanos-related gene is essential for the development of primordial germ cells

Asymmetrically distributed cytoplasmic determinants collectively termed ger m plasm have been shown to play an essential role in the development of pri mordial germ cells (PGCs). Here, we report the identification of a nanos-li ke (nanos1) gene, which is expressed in the germ plasm and in the PGCs of t he zebrafish. We find that several mechanisms act in concert to restrict th e activity of Nanos1 to the germ cells including RNA localization and contr ol over the stability and translatability of the RNA. Reducing the level of Nanos1 in zebrafish embryos revealed an essential role for the protein in ensuring proper migration and survival of PGCs in this vertebrate model org anism.