title: P granules in the germ cells of Caenorhabditis elegans adults are associated with clusters of nuclear pores and contain RNA.
abstract: The germ cells, and germ cell precursors, in the nematode Caenorhabditis elegans contain distinctive granules called P granules. During early embryogenesis, P granules are segregated asymmetrically into those blastomeres that eventually produce the germ line. Because of the correlation between P granule distribution and the development of the germ line, P granules are widely thought to function in some aspect of germ line specification or differentiation. Most of the analysis of P granule structure and localization has focused on the early embryo, when P granules are located in the cytoplasm. However, during most of development P granules are associated with germ cell nuclei. We report here an ultrastructural analysis of the nuclear-associated P granules in the germ cells of the adult hermaphrodite gonad. We show that P granules are tightly associated with nuclear pores and that the positions of certain structures within the P granules correspond to the positions of pores on the nuclear envelope. We present immunocytochemical and ultrastructural data suggesting that P granules can associate, or remain associated, with pore-like structures even after they detach from the nuclear envelope during oogenesis. Finally, we show that nuclear-associated P granules in the gonad contain RNA, complementing previous studies showing that cytoplasmic P granules in embryos contain RNA.
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, 98109, USA.
authors.forename: J N
authors.initials: JN
authors.lastname: Pitt
authors.forename: J A
authors.initials: JA
authors.lastname: Schisa
authors.forename: J R
authors.initials: JR
authors.lastname: Priess
mesh_terms: D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure*; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure; D015342:DNA Probes / Q000235:genetics; D005260:Female; D005854:Germ Cells / Q000378:metabolism* / Q000648:ultrastructure*; D017403:In Situ Hybridization; D008297:Male; D008854:Microscopy, Electron; D009685:Nuclear Envelope / Q000378:metabolism / Q000648:ultrastructure; D012326:RNA Splicing; D018510:RNA, Helminth / Q000235:genetics / Q000378:metabolism*
chemical_list: D015342:DNA Probes; D018510:RNA, Helminth