Hybrid sterility has been widely observed in fish species; however, the molecular mechanisms of hybrid sterility are not well understood. In this work, we compared the reproductive development of yellow catfish (Pelteobagrus fulvidraco, PF) and hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × Pelteobagrus vachelli ♂) from embryo to adult at cellular and molecular levels. Firstly, we developed a pair of genetic markers to efficiently distinguish PF and PV (Pelteobagrus vachelli) and their interspecific hybrid. Hybrid sterility was observed in hybrid yellow catfish, as indicated by the germ cell-less phenotype and defective gonadal development. The expression levels of germ cell differentiation-related and gonadal somatic cell development-related genes were obviously down-regulated in PF × PV hybrid than in PF. In addition, meiotic and mitotic defects were detected in the testis of PF × PV hybrid, since the numbers of Sycp3- and PH3-positive cells were obviously reduced. As early as 4-cell stage, defects of germplasm assembly and accelerated decay of maternal germline-specific mRNAs were observed in hybrid yellow catfish. Our studies provide evidence that hybrid sterility in animals might be caused by the accelerated decay of germplasm mRNAs, impaired germplasm assembly and defective germ cell development.

中文翻译：

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有缺陷的种质组装和生殖细胞发育导致黄鲶杂交不育

在鱼类物种中广泛观察到杂交不育。然而，杂交不育的分子机制尚不清楚。在这项工作中，我们在细胞和分子水平上比较了黄鲶 ( Pelteobagrus fulvidraco , PF) 和杂交黄鲶 ( Pelteobagrus fulvidraco ♀ × Pelteobagrus vachelli ♂) 从胚胎到成年的生殖发育。首先，我们开发了一对遗传标记来有效区分 PF 和 PV ( Pelteobagrus vachelli) 及其种间杂种。在杂交黄鲶中观察到杂交不育，如无生殖细胞表型和性腺发育缺陷所示。PF×PV杂种中生殖细胞分化相关基因和性腺体细胞发育相关基因的表达水平明显低于PF。此外，在PF×PV杂种的睾丸中检测到减数分裂和有丝分裂缺陷，因为Sycp3-和PH3-阳性细胞的数量明显减少。早在 4 细胞阶段，在杂交黄鲶中观察到种质组装缺陷和母系种系特异性 mRNA 的加速衰减。我们的研究提供的证据表明，动物的杂交不育可能是由种质 mRNA 的加速衰变、种质组装受损和生殖细胞发育缺陷引起的。