基于天然XY雌鱼培育YY超雄尼罗罗非鱼的新方法

前期报道了利用尼罗罗非鱼LG22上性别连锁的分子标记检测到养殖群体存在天然XY雌鱼，但其能否用于培育YY超雄罗非鱼尚不清楚。本研究首先引入遗传性别受LG22染色体严格控制的CQ尼罗罗非鱼群体和具有天然XY雌鱼的WC群体，将CQ群体XY雄鱼与WC XY雌鱼杂交，检验杂交F1 YY超雄鱼是否可用于控制后代性别，并比较杂交F1 XY和YY罗非鱼体质量、性腺指数、血清激素水平和性腺基因表达情况。研究发现，CQ XY雄鱼和WC XY雌鱼交配，获得的F1 中具有25%的YY超雄鱼，经鉴定为全雄且可育。将F1 YY超雄鱼与WC XX雌鱼、WC XY雌鱼（母本）、杂交F1 XX雌鱼和CQ XX雌鱼交配，后代几乎全雄，仅在与F1 XX雌鱼交配后代中有2尾雌鱼（雄性率98%）。在孵化后180 d，杂交F1中XY和YY个体的体重、性腺指数、血清激素水平差异不显著。基因表达分析发现，YY鱼精巢中AmhX/AmhY mRNA表达显著高于XY鱼，而Dmrt1 和Cyp11b2 mRNA表达水平差异不显著。杂交F1 YY和XY鱼生理指标无明显差异。因此，采用尼罗罗非鱼天然XY雌鱼能够培育YY超雄鱼，且该YY超雄鱼能够用于罗非鱼性别控制。

A new method to produce YY super-male Nile tilapia (Oreochromis niloticus) by using naturally sex-reversed XY female

Previously naturally sex-reversed XY females were found in several Oreochromis niloticus populations identified by a sex-linked marker on LG22, while it is unclear whether the naturally sex-reversed XY females could be used for breeding of YY supermale. CQ and WC O. niloticus populations were introduced. The genetic sexes of CQ and WC are controlled strictly and not strictly by LG22 chromosome, respectively. YY supermales were obtained by crossing CQ XY male fish with WC XY female fish, and whether the F1 YY male could be used for sex control was tested. The body weight, gonadal somatic index (GSI), serum hormone level and gonadal gene expression patterns in XY and YY individuals of F1 generation were analyzed. A quarter of YY supermales were obtained in the F1 generation of the progeny of CQ XY male and WC XY females. F1 YY supermales were all male and fertile. F1 YY supermales were crossed with WC XX female, WC XY female (dam), F1 XX female and CQ XX female, and their offspring were almost all male. Two female fish were found in the progeny of the F1 YY male and F1 XX female, and the male ratio is 98%. At 180 days after hatching, there were no significant differences in body weight, GSI and serum hormone levels between F1 XY and YY hybrids. Testicular gene expression analysis showed that the expression levels of AmhX/AmhY in YY were significantly higher than that of XY fish, while the expression levels of Dmrt1 and Cyp11b2 were not significantly different between XY and YY individuals. The physiological status of YY fish are highly similar to those of XY fish. Naturally sex-reversed XY female O. niloticus can be used for breeding YY supermale fish, which can be used for tilapia sex control.