RT Journal Article SR Electronic T1 Extensive nuclear gyration and pervasive non-genic transcription during primordial germ cell development in zebrafish JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.01.10.901306 DO 10.1101/2020.01.10.901306 A1 Stefan Redl A1 Antonio M. de Jesus Domingues A1 Stefanie Möckel A1 Willi Salvenmoser A1 Maria Mendez-Lago A1 René F. Ketting YR 2020 UL http://biorxiv.org/content/early/2020/01/10/2020.01.10.901306.abstract AB Primordial germ cells (PGCs) are the precursors of germ cells, which migrate to the genital ridge during early development. Relatively little is known about PGCs after their migration. We studied this post-migratory stage using microscopy and sequencing techniques, and found that many PGC-specific genes, including genes known to induce PGC fate in the mouse, are only activated several days after migration. At this same timepoint, PGC nuclei become extremely gyrated, displaying general opening of chromatin and high levels of transcription. This is accompanied by changes in nuage morphology, expression of large loci, named PERLs, enriched for retro-transposons and piRNAs, and a rise in piRNA biogenesis signatures. Interestingly, no nuclear Piwi protein could be detected at any timepoint, indicating that the zebrafish piRNA pathway is fully cytoplasmic. Our data show that the post-migratory stage of zebrafish PGCs holds many cues to both germ cell fate establishment and piRNA pathway activation.