The sex-determining genes are found to be variable among different fish species. Yellow catfish (Pelteobagrus fulvidraco) is an important aquaculture fish species in China with XX/XY sex-determining type. Recently, YY super-male yellow catfish has been successfully produced by combining hormonal-induced sex reversal method with sex chromosome-linked markers. Here, we identified a novel PDZ domain-containing gene in yellow catfish designated as pfpdz1, in whose intron the sex-linked marker was located. The coding sequence of pfpdz1 in Y chromosome was identical to that in X chromosome except a missense SNP (A/T) that changes an amino acid (E8V) in the N-terminal region. Pfpdz1 displayed male-specific expression during sex differentiation. Overexpression of pfpdz1 using additive transgenesis induces XX ovary to differentiate into testis-like tissue, while the targeted inactivation of pfpdz1 in Y chromosome using CRISPR/Cas9-mediated mutagenesis triggers ovarian differentiation. Furthermore, we demonstrated that pfpdz1 initiates testicular differentiation through upregulating expression of amh, dmrt1 and sox9a1, as well as downregulating expression of cyp19a1, foxl2 and wnt4. Our data provide functional evidence that pfpdz1 is significant for male differentiation and maintenance in yellow catfish.

发现性别决定基因在不同鱼类中是可变的。黄颡鱼（Pelteobagrus fulvidraco）是我国重要的水产养殖鱼类，具有XX/XY性别决定型。近期，通过激素诱导性逆转方法与性染色体连锁标记相结合，成功培育出YY超雄性黄颡鱼。在这里，我们在黄鲶中发现了一个新的包含 PDZ 结构域的基因，命名为pfpdz1，性连锁标记位于其内含子中。Y 染色体中pfpdz1的编码序列与X 染色体中的相同，除了错义 SNP (A/T) 改变了 N 末端区域的氨基酸 (E8V)。Pfpdz1在性别分化过程中表现出雄性特异性表达。使用加性转基因过表达pfpdz1可诱导 XX 卵巢分化为睾丸样组织，而使用 CRISPR/Cas9 介导的诱变在 Y 染色体中靶向失活pfpdz1可触发卵巢分化。此外，我们证明pfpdz1通过上调amh、dmrt1和sox9a1的表达以及下调cyp19a1、foxl2和wnt4的表达来启动睾丸分化。我们的数据提供了pfpdz1的功能证据对黄颡鱼的雄性分化和维持具有重要意义。