SRA

Xenopus primordial germ cells (PGCs) are determined by the presence of maternally derived germ plasm. Germ plasm components both protect PGCs from somatic differentiation and begin a unique gene expression program. Segregation of the germline from the endodermal lineage occurs during gastrulation and PGCs subsequently initiate zygotic transcription. However, the gene-networks that operate to both preserve the potential for totipotency and promote germline differentiation are poorly understood. Here, we utilized RNA-sequencing analysis to comprehensively interrogate PGC and neighboring endoderm cell RNAs after lineage segregation. We identified 1,865 transcripts enriched in PGCs compared to endoderm cells. Over 50% of maternal, vegetally-enriched transcripts were enriched in the PGC transcriptome, including sox7. PGC-directed sox7 knockdown and over-expression studies revealed an early requirement for sox7 in proper germ plasm localization, zygotic transcription, and PGC number. We identified oct60 as the most highly expressed and enriched OCT3/4 homologue in PGCs. Lastly, we compared the Xenopus PGC transcriptome with human PGC transcripts and showed that 80% of transcripts are conserved, identifying Xenopus as a relevant model system for understanding the gene-networks necessary for human germline development. Overall design: Examination of X. laevis primordial germ cell (PGC) and neighboring endoderm cell (Endo) RNAs after lineage segregation to determine PGC-enriched transcripts that may contribute to germline development.