Transcriptional quiescence, an evolutionarily conserved trait, distinguishes the embryonic primordial germ cells (PGCs) from their somatic neighbors. InDrosophila melanogaster, PGCs from embryos maternally compromised forgerm cell-less(gcl) misexpress somatic genes, possibly resulting in PGC loss. Recent studies documented a requirement for Gcl during proteolytic degradation of the terminal patterning determinant, Torso receptor. Here we demonstrate that the somatic determinant of female fate,Sex-lethal(Sxl), is a biologically relevant transcriptional target of Gcl. Underscoring the significance of transcriptional silencing mediated by Gcl, ectopic expression of a degradation-resistant form of Torso (torsoDeg) can activateSxltranscription in PGCs, whereas simultaneous loss oftorso-like(tsl) reinstates the quiescent status ofgclPGCs. Intriguingly, likegclmutants, embryos derived from mothers expressingtorsoDegin the germline display aberrant spreading of pole plasm RNAs, suggesting that mutual antagonism between Gcl and Torso ensures the controlled release of germ-plasm underlying the germline/soma distinction.
