Cover image

PIE-1 is required for the efficient expression of maternally encoded factors in the Caenorhabditis elegans germ-line. Shown here are three time-lapse Normarski images of a single embryo expressing a version of pie-1 in which the second zinc finger is mutated. Regulation of the Nanos homologue NOS-2 by PIE-1 is required for the proper positioning of primordial germ cells during embryogenesis. A mutation in the second CCCH finger of PIE-1 causes a reduction in NOS-2 expression, and the subsequent displacement of primordial germ cells from the somatic gonad. As visualized here, a germ cell exits the embryo completely, and floats freely within the confines of the egg shell. This novel action of PIE-1 is independent from its previously identified role in germ cell transcriptional quiescence. (For details, see Tenenhaus et al., p. 1031).