bioRxiv preprint doi: https://doi.org/10.1101/397992; this version posted August 22, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. PHASE TRANSITIONED NUCLEAR OSKAR PROMOTES CELL DIVISION OF DROSOPHILA PRIMORDIAL GERM CELLS Kathryn E. Kistler*1,2, Tatjana Trcek*†1, Thomas R. Hurd1, Ruoyu Chen1, Feng-Xia Liang3, Joseph Sall3, Masato Kato4, Ruth Lehmann†1 1: HHMI, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, NY, USA 2: Department of Molecular and Cellular Biology, University of Washington, WA, USA 3: DART Microscopy Laboratory, NYU Langone Health, NY, USA 4: Department of Biochemistry, University of Texas Southwestern Medical Center, TX, USA ORCID ID Trcek Tatjana: 0000-0003-4405-8733 *: equal contribution †: correspondence (
[email protected];
[email protected]) ABSTRACT Germ granules are non-membranous ribonucleoprotein granules deemed the hubs for post-transcriptional gene regulation and functionally linked to germ cell fate across species. Little is known about the physical properties of germ granules and how these relate to germ cell function. Here we study two types of germ granules in the Drosophila embryo: cytoplasmic germ granules that instruct primordial germ cells (PGCs) formation and nuclear germ granules within early PGCs with unknown function. We show that cytoplasmic and nuclear germ granules are phase transitioned condensates nucleated by Oskar protein that display liquid as well as hydrogel-like properties.