Nanos keeps its job

The Drosophila gene nanos was first identified as an RNA-binding protein whose absence prevented primordial germ cells (PGCs) from migrating to the gonad, resulting in a loss of functional germ cells. Subsequently, a variety of nanos homologs have been found in other systems, including a single mouse nanos gene (nanos1), the disruption of which had no affect on PGCs or germ cell development. The mechanism for specifying and maintaining PGCs in mice has been unclear, but it was suspected that other nanos-related genes might exist. In the August 29 Science, Masayuki Tsuda and colleagues at the National Institute of Genetics report the identification of two additional mouse nanos genes and show their requirement for germ cell development (Science, 301:1239-1241, August 29, 2003).

Tsuda et al. identified two homologs of the mouse nanos1 gene by searching the human genome for a conserved zinc finger...