During animal development, the spatio-temporal regulation of gene transcription is essential to regulate cell behavior. Precise regulation of gene transcription, recruitment, and activation of RNA polymerase II (pol II) to the transcriptional target is required. RNA polymerase II-associated factor 1 complex (PAF1C) is a protein complex that consists of PAF1, CDC73, CTR9, LEO1, and RTF1, is involved in pol II-mediated transcriptional regulation, including transcriptional activation, transcriptional inactivation, and chromatin remodeling. Although PAF1C regulates a variety of biological processes including cell proliferation and differentiation, preservation of stem cells, and regulation of tumor formation, the precise role of PAF1C during development has not been fully clarified. The Caenorhabditis elegans hermaphrodite gonad temporally produces sperm at the fourth larval stage. The sperm is reserved in the spermatheca. Subsequently, oocyte production occurs at the adult stage. Finally, gametogenesis is achieved by self-fertilization. However, the mechanism of oogenesis is unclear. In this study, oogenesis was not detected in a putative null allele of the rtfo-1
) mutant. In addition, oogenesis was not observed in a putative null allele of the leo-1
) mutant at the young adult stage. Next, we checked whether all of the components of PAF1C are involved in the regulation of the oogenesis by performing feeding RNA interference (RNAi) experiments. Oogenesis occurred in control (RNAi) animals. In contrast, oogenesis was not observed in the leo-1
(RNAi) animals at the young adult stage. Moreover, although most animals displayed embryonic lethality or larval arrest, as shown previously (Kubota Y et al., Dev Biol, 2014), oogenesis was not observed in rtfo-1
(RNAi) , and cdc-73
(RNAi) animals at the young adult stage of the escapers. We also found that the functional GFP::LEO-1 expressed from an integrated genomic transgene, tjIs308[leo-1p
], localized nuclei of the germ cells. This localization was absent at the young adult stage of the leo-1
(RNAi) animals. Thus, nuclear localization of PAF1C might be essential for germline development. Taken together, these results suggest that PAF1C is involved in the promotion of oogenesis and/or the switch from spermatogenesis to oogenesis.