Identification, expression, and function analysis of Rbpms2 splicing variants in Japanese flounder gonad

•The two splicing variants of Japanese flounder Rbpms2 were abundantly expressed in gonads.•Rbpms2 was mainly located in early oocytes and primary spermatocytes (PSCs).•Rbpms2 may be involved in gonadal development by targeting gonad-related genes such as dmrt1, sox9, amh, foxl2, and wnt4. Rbpms2, an RNA-binding protein with multiple splicing (Rbpms), can interact with RNAs to involve oocyte development, thereby influencing female sex differentiation in vertebrates. Here, two splicing variants of the Rbpms2 gene from Japanese flounder (Paralichthys olivaceus) were identified, namely Rbpms2.1 and Rbpms2.2. The two variants exhibited 98.22 % amino acid homology, both featuring an RNA recognition motif (RRM) domain spanning positions 98–170 amino acids. They were relatively conserved throughout phylogenetic evolution. Differently, the C-terminal region of the Rbpms2.1 contains five additional sequential amino acids (–VRDQP–) compared to Rbpms2.2. The real-time qPCR results demonstrated that Rbpms2.1 and Rbpms2.2 had relatively abundant expression in the gonads of adult Japanese flounder, with higher expression levels in the ovary compared to the testis (P