Germline development in rat revealed by visualization and deletion of Prdm14

Primordial germ cells (PGCs), the founder cells of the germline, are specified in pre-gastrulating embryos in mammals, and subsequently migrate towards gonads to mature into functional gametes. Here, we investigated PGC development in rats, by genetically modifying Prdm14, a unique marker and a critical PGC transcriptional regulator. We trace PGC development in rats, for the first time, from specification until sex determination stage in fetal gonads using Prdm14 H2BVenus knock-in rats. We uncover that Prdm14’s crucial role in PGC specification is conserved between rat and mice, by analyzing Prdm14 deficient rat embryos. Notably, loss of Prdm14 completely abrogates the PGC program: failure in maintenance and/or activation of germ cell markers and pluripotency genes. Finally, we profile the transcriptome of the postimplantation epiblast and all PGC stages in rat, to reveal enrichment of distinct gene sets at each transition point, thereby providing an accurate transcriptional time-line for rat PGC development. Thus, the novel genetically modified rats and data sets obtained in this study will advance our knowledge on conserved vs species-specific features for germline development in mammals. RNA-seq of rat primordial germ cells and epiblasts.