Reproductive strategies and spawning habits play key roles in the evolution of endemic East Asian cyprinids. However, the molecular mechanisms underlying the regulation of spawning habits are not well understood. We recently identified zona pellucida (Zp) as the top differentially expressed protein between East Asian cyprinids that produce adhesive and semi-buoyant eggs, suggesting that Zp protein may play important roles in the regulation of egg type. In this work, we generated transgenic zebrafish in which oocyte-specific expression of zp genes from rare minnow ( Gobiocypris rarus), an East Asian cyprinid laying adhesive eggs, was driven by a zebrafish zp3.2 gene promoter. We found that the transgenic eggs obtained partial adhesiveness and exhibited alteration in hydration and buoyancy. Abnormal metabolism of vitellogenin (VTG) may contribute to enhanced hydration and/or buoyancy. Our work shows that expression of the exogenous zp3a gene from an adhesive-egg producing fish is sufficient to induce changes in both egg adhesiveness and buoyancy in zebrafish, emphasizing the important role of zp genes in the regulation of spawning habits. Our results thus provide new insights into how endemic East Asian cyprinids may have adapted to the Yangtze river-lake system via changes in spawning habits.
繁殖策略和产卵习性对于鲤科鱼类东亚特有类群的演化具有重要意义。然而，调控产卵习性的分子机制尚未明确。我们近期的研究发现，在产黏性卵和半浮性卵的东亚鲤科鱼类中，Zp蛋白的表达量差异最大，提示其在卵型调控中可能具有重要作用。稀有鮈鲫（ Gobiocypris rarus）是一种产黏性卵的东亚特有理科鱼类，在该研究中，我们利用斑马鱼 zp3.2基因的启动子，构建了能表达稀有鮈鲫卵巢特异性Zp蛋白的转基因斑马鱼品系。我们发现转基因品系所产鱼卵获得了部分黏性并且水合作用以及浮性也出现变化。过去有研究指出，卵黄蛋白原代谢异常可能导致鱼卵水合作用和/或浮性发生改变。我们的研究表明，在斑马鱼中内源性表达产黏性卵鱼类的 zp3a基因，就足以引起其鱼卵的黏性及浮性都发生变化，暗示着 zp基因在调控鱼卵类型中具有重要作用。我们的结果为鲤科鱼类东亚特有类群如何通过改变产卵习性适应长江江湖复合生态系统提供了新见解。.
Keywords: Adhesive; Buoyancy; Egg envelope; Hydration; Zona pellucida protein.