title: Germline P granules are liquid droplets that localize by controlled dissolution/condensation.
abstract: In sexually reproducing organisms, embryos specify germ cells, which ultimately generate sperm and eggs. In Caenorhabditis elegans, the first germ cell is established when RNA and protein-rich P granules localize to the posterior of the one-cell embryo. Localization of P granules and their physical nature remain poorly understood. Here we show that P granules exhibit liquid-like behaviors, including fusion, dripping, and wetting, which we used to estimate their viscosity and surface tension. As with other liquids, P granules rapidly dissolved and condensed. Localization occurred by a biased increase in P granule condensation at the posterior. This process reflects a classic phase transition, in which polarity proteins vary the condensation point across the cell. Such phase transitions may represent a fundamental physicochemical mechanism for structuring the cytoplasm.
authors.affiliation: Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
authors.forename: Clifford P
authors.initials: CP
authors.lastname: Brangwynne
authors.forename: Christian R
authors.initials: CR
authors.lastname: Eckmann
authors.forename: David S
authors.initials: DS
authors.lastname: Courson
authors.forename: Agata
authors.initials: A
authors.lastname: Rybarska
authors.forename: Carsten
authors.initials: C
authors.lastname: Hoege
authors.forename: Jöbin
authors.initials: J
authors.lastname: Gharakhani
authors.forename: Frank
authors.initials: F
authors.lastname: Jülicher
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Hyman
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism; D055598:Chemical Phenomena; D003593:Cytoplasm / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D004625:Embryo, Nonmammalian / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D005854:Germ Cells / Q000648:ultrastructure*; D044367:Phase Transition; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism; D034622:RNA Interference; D018510:RNA, Helminth / Q000737:chemistry; D012995:Solubility; D013500:Surface Tension; D014783:Viscosity
chemical_list: D029742:Caenorhabditis elegans Proteins; C410587:MEX-5 protein, C elegans; D018510:RNA, Helminth; C409406:PAR-1 protein, C elegans; D017346:Protein Serine-Threonine Kinases