ZFIN ID: ZDB-PUB-190212-3
Aggregation, segregation and dispersal of homotypic germ plasm RNPs in the early zebrafish embryo
Eno, C., Hansen, C.L., Pelegri, F.
Date: 2019
Source: Developmental dynamics : an official publication of the American Association of Anatomists   248(4): 306-318 (Journal)
Registered Authors: Pelegri, Francisco
Keywords: germ plasm fragmentation, germ plasm inheritance, ribonucleoparticles
MeSH Terms:
  • Animals
  • Blastula
  • Cytoplasm/metabolism
  • Embryo, Nonmammalian*/ultrastructure
  • Germ Cells/ultrastructure
  • RNA/metabolism*
  • Zebrafish/embryology
  • Zebrafish/genetics
PubMed: 30741457 Full text @ Dev. Dyn.
In zebrafish and many other organisms, specification of primordial germ cells (PGCs) requires the transmission of maternally-derived germ plasm. Zebrafish germ plasm ribonucleoparticles (RNPs) aggregate along the cleavage furrows during the first several cell cycles, segregate asymmetrically during the cleavage stages, and undergo cytoplasmic dispersal in the late blastula.
For all tested germ plasm RNAs [carbonic anhydrase 15b (ca15b), deleted in azoospermia-like (dazl), dead end (dnd), nanos 3 (nos3), regulator of G-protein signaling14a (rgs14a), and vasa/DEAD box polypeptide 4 (vasa/ddx4)], RNPs are homotypic (containing a single RNA type), with RNPs packing tightly yet remaining distinct within germ plasm aggregates. Homotypic clustering of RNAs within RNPs is observed prior to aggregation in the cortex and is maintained through germ plasm recruitment, asymmetric segregation and RNP dispersal. We also identify a step of germ plasm fragmentation during the cleavage stages that precedes RNP dispersal.
Our findings suggest that germ plasm aggregates act as subcellular compartments that temporarily collect and carry single RNA-type RNPs from fertilization until their cytoplasmic dispersal in PGCs at the end of the blastula period, and describe a previously unknown fragmentation step that allows for an increase in the pool of germ plasm-carrying cells, presumably PGCs. This article is protected by copyright. All rights reserved.