黄颡鱼XX伪雄鱼诱导与全雌种群规模化繁育

研究利用3种雄性化因素, 包括17α-甲基睾丸酮(MT, 5 mg/kg)、来曲唑(LZ, 300 mg/kg)和高温(33.5℃) 联合处理12—65日龄黄颡鱼幼鱼, 并将性成熟的XX伪雄鱼与正常XX雌鱼进行人工繁殖, 开展了全雌黄颡鱼(Tachysurus fulvidraco)规模化繁殖与苗种培育工作。研究发现, MT、LZ和高温共同作用可诱导XX黄颡鱼逆转为生理型雄性, 完全性逆转个体运动型精子比例与XY雄鱼无显著性差异, 组织学切片也显示其精巢中存在大量精子细胞, 推测XX伪雄鱼具有正常的繁殖功能。随后, 以XX伪雄鱼为父本, 正常XX雌鱼为母本开展了规模化人工繁殖, 获得了57万尾基因型全部为XX的黄颡鱼苗种, 并将其成功培育成大规格鱼种。在幼鱼60日龄和120日龄时取样发现, 分别有2.8%和12.0%的个体发生了不同程度的雄性化, 推测其可能受到池塘自然高温的影响而发生了性逆转。其余XX雌鱼卵巢发育良好, 来年繁殖季节可作为规模化人工繁殖的雌性亲本。研究成功开展了全雌黄颡鱼规模化繁育工作, 为全雌黄颡鱼规模化繁育体系的建立提供了基础, 也为黄颡鱼新品种选育中雌性选育提供了保障。

INDUCTION OF XX PSEUDO-MALES,AND LARGE-SCALE REPRODUCTION OF ALL-FEMALE POPULATION IN YELLOW CATFISH

The shortage of female has impeded the development of aquaculture industry of yellow catfish (Tachysurus fulvidraco) in China in recent years. Therefore, large-scale production system of all-female is urgently needed. To produce an all-female population in large-scale of yellow catfish, 12—65 days post-hatching larvae were treated with the combination of three male-promoting factors, 17 α-Methyltestosterone (MT, 5 mg/kg), Letrozole (LZ, 300 mg/kg), and high temperature (33.5℃). XX pseudo-males were mated with normal XX females and large-scale production of all-female population was conducted. Results showed that the combination of MT, LZ, and high temperature-induced masculinization of XX individuals, and the completely sex-reversed XX males displayed a similar percentage of motile sperm with XY males. Histological observation found that there are a large number of spermatids in the testis of XX males, indicating normal reproductive ability. Subsequently, we mate XX males and XX females, produced 570000 genotypic XX larvae, and successfully reared them to large fingerlings in a pond. The results indicated that 2.8% and 12.0% XX individuals reversed to XX males which is probably due to the high temperature during the critical time of sex differentiation in the rearing pond. The ovary developed very well for the rest of XX females and can be used as female parents in the coming spawning season. The current work successfully conducted large-scale production of the all-female population in yellow catfish, and the results will provide an important foundation for the large-scale production system of the all-female population, and important safeguard for female selection in genetic breeding of new varieties.