Identification and expression analysis of dmc1 in Chinese soft-shell turtle (Pelodiscus sinensis) during gametogenesis

DNA meiotic recombinase 1 (disrupted meiotic cDNA, Dmc1) protein is homologous to the Escherichia coli RecA protein, was first identified in Saccharomyces cerevisiae. This gene has been well studied as an essential role in meiosis in many species. However, studies on the dmc1 gene in reptiles are limited. In this study, a cDNA fragment of 1,111 bp was obtained from the gonadal tissues of the Chinese soft-shell turtle via RT-PCR, containing a 60 bp 3' UTR, a 22 bp 5' UTR, and an ORF of 1,029 bp encoding 342 amino acids, named Psdmc1. Multiple sequence alignments showed that the deduced protein has high similarity (>95 %) to tetrapod Dmc1 proteins, while being slightly lower (86-88 %) to fish species.Phylogenetic tree analysis showed that PsDmc1 was clustered with the other turtles' Dmc1 and close to the reptiles', but far away from the teleost's. RT-PCR and RT-qPCR analyses showed that the Psdmc1 gene was specifically expressed in the gonads, and much higher in testis than the ovary, especially highest in one year-old testis. In situ hybridization results showed that the Psdmc1 was mainly expressed in the perinuclear cytoplasm of primary and secondary spermatocytes, weakly in spermatogonia of the testes. These results indicated that dmc1 would be majorly involved in the developing testis, and play an essential role in the germ cells' meiosis. The findings of this study will provide a basis for further investigations on the mechanisms behind the germ cells' development and differentiation in Chinese soft-shell turtles, even in the reptiles.