Cytoplasmic partitioning of P granule components is not required to specify the germline in C. elegans.
Asymmetric segregation of P granules during the first four divisions of the Caenorhabditis elegans embryo is a classic example of cytoplasmic partitioning of germline determinants. It is thought that asymmetric partitioning of P granule components during mitosis is essential to distinguish germline from soma. We have identified a mutant (pptr-1) in which P granules become unstable during mitosis and P granule proteins and RNAs are distributed equally to somatic and germline blastomeres. Despite symmetric partitioning of P granule components, pptr-1 mutants segregate a germline that uniquely expresses P granules during postembryonic development. pptr-1 mutants are fertile, except at high temperatures. Hence, asymmetric partitioning of maternal P granules is not essential to specify germ cell fate. Instead, it may serve to protect the nascent germline from stress.
Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 North Wolfe Street, PCTB 706, Baltimore, MD 21205, USA.
Christopher M
CM
Gallo
Jennifer T
JT
Wang
Fumio
F
Motegi
Geraldine
G
Seydoux
D000818:Animals; D001757:Blastomeres / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000502:physiology* / Q000648:ultrastructure; D004625:Embryo, Nonmammalian / Q000502:physiology; D047108:Embryonic Development; D005854:Germ Cells / Q000502:physiology*; D007399:Interphase; D018613:Microscopy, Confocal; D008938:Mitosis; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018510:RNA, Helminth / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015053:Zygote / Q000502:physiology
D029742:Caenorhabditis elegans Proteins; D009687:Nuclear Proteins; C114543:PGL-1 protein, C elegans; D018510:RNA, Helminth; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C100950:pie-1 protein, C elegans; C539316:pptr-1 protein, C elegans; C409406:PAR-1 protein, C elegans; D017346:Protein Serine-Threonine Kinases