Cytoplasmic Partitioning of P Granule Components Is Not Required to Specify the Germline in C. elegans

Abstract

Making a Germ Cell When it comes to generating the germ line, animals fall into two classes: those, like mammals, which use inductive interactions to specify the germ line and those, like nematodes, which use germ plasm—a specialized egg cytoplasm that segregates asymmetrically in embryos. Germ plasm contains germ, or P, granules—RNA-protein aggregates that have been thought to harbor the germ line determinants. Now, Gallo et al. (p. 1685 , published online 2 December) describe a Caenorhabditis elegans mutant that challenges this belief. The germ line still formed even when germ granule components were missegregated. Thus, even in animals with germ plasm, germ granules appear to be a consequence, not a cause, of germ cell specification.