人工诱导瓦氏黄颡鱼性逆转及雌核发育

Artificially induced sex-reversal and gynogenesis in darkbarbel catfish (Pelteobagrus vachelli)

摘要:

目的 瓦氏黄颡鱼和杂交黄颡鱼 (瓦氏黄颡鱼♂×黄颡鱼♀)具有明显的两性生长异形特征。为了创制生长速率快的瓦氏黄颡鱼和杂交黄颡鱼的单性养殖新品系，开展了鱼类性别控制技术和人工诱导雌核发育技术的相关研究，以期获得YY超雄瓦氏黄颡鱼。方法 研究戊酸雌二醇 (EV)和17β-雌二醇 (E₂)不同处理浓度，及E₂不同处理时间对瓦氏黄颡鱼性腺分化、生长和存活率的影响，再使用性逆转的瓦氏黄颡鱼个体探索雌核发育的最佳条件。结果 在7~60 dph，使用低浓度EV (5和10 mg/kg)处理的瓦氏黄颡鱼存在性逆转不彻底的现象，而20和40 mg/kg E₂处理的瓦氏黄颡鱼比EV处理组体长、体重和存活率更高，且雌性率高达100%；22~40 dph为最短有效处理时间，使用20 mg/kg E₂处理的瓦氏黄颡鱼100%雌性率，其生长速率和存活率最接近对照组的瓦氏黄颡鱼。水温25 °C时，瓦氏黄颡鱼受精卵第二极体与雌原核开始分离时间为6 min，4 °C冷休克20 min处理获得的雌核发育二倍体效果最佳。通过使用能够区分瓦氏黄颡鱼、黄颡鱼及其杂交种的分子标记，共鉴定到62尾雌核发育个体，随机挑选10尾解剖后发现3尾雄性瓦氏黄颡鱼，推断其为YY超雄鱼。结论 E₂处理能高效诱导瓦氏黄颡鱼雌性化，利用性逆转的瓦氏黄颡鱼进行雌核发育可获得超雄鱼，为全雄瓦氏黄颡鱼和全雄杂交黄颡鱼的品种改良和新品种培育奠定了基础。

Abstract:

Pelteobagrus vachelli and hybrid yellow catfish (P. vachelli♂×P. fulvidraco♀) exhibit significantly sexual dimorphism in growth. To obtain monosex populations of P. vachelli and hybrid catfish with improved growth performances, we investigated sex control technology and gynogenesis to produce YY super-male P. vachelli. First, we explored the effects of different dosages of estradiol valerate (EV) and 17β-estradiol (E₂), as well as various treatment periods of E₂, on gonadal differentiation, growth, and survival rate of P. vachelli. Then, the sex-reversed fish were used to identify the best condition for gynogenesis. Results showed that lower EV treatments (5 and 10 mg/kg) led to incomplete sex reversal in P. vachelli during 7-60 day-post hatching (dph). In contrast, 20 and 40 mg/kg E₂ treatments resulted in complete feminization, with significantly higher body length, body weight, and survival rate compared to EV-treated fish. The feminization rate of P. vachelli treated with 20 mg/kg E₂ was 100% during 22-40 dph, with growth performance and survival rate comparable to the control group. Cytological observations revealed that the separation of the second polar body from the female pronucleus of the fertilized egg occurred as early as 6 min post-fertilization at 25 °C. We optimized gynogenesis conditions by applying cold shock at 4 °C for 20 min to eggs at 6 min post-fertilization. A total of 62 gynogenetic fish were identified using a pair of genetic markers that efficiently distinguished yellow catfish, darkbarbel catfish, and their interspecific hybrids. Of these, 10 gynogenetic fish were sacrificed, and three were males, inferred to be YY super-males. Our results indicate that E₂ treatment efficiently induces feminization of P. vachelli, and YY super-males can be obtained through gynogenesis of feminized P. vachell. This laid the foundation for the improvement and cultivation of all-male P. vachelli and all-male hybrid yellow catfish (P. vachelli, ♂×P. fulvidraco, ♀).