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Abstract：
Farmed Atlantic salmon are one of the most economically significant global aquaculture products. Early sexual maturation of farmed males represents a significant challenge to this industry and has been linked with the vgll3 genotype. However, tools to aid research of this topic, such as all-male and clonal fish, are still lacking. The present 6-year study examined if all-male production is possible in Atlantic salmon, a species with heteromorphic sex chromosomes (males being XY, females XX), and if all-male fish can be applied to further explore the vgll3 contribution on the likelihood of early maturation.
Estrogen treatment of mixed sex yolk sac larvae gave rise to one sexually mature hermaphrodite with a male genotype (XY) that was used to produce both self-fertilized offspring and androgenetic double haploid (dh) offspring following egg activation with UV treated sperm and pressure shock to block the first mitotic division. There were YY supermales among both offspring types, which were crossed with dh females. Between 1 and 8% of the putative all-male offspring from the eight crosses with self-fertilized supermales were found to have ovaries, and 95% of these phenotypic females were also genetically female. None of the offspring from the one dh supermale cross had ovaries. When assessing the general contribution of the vgll3 locus on the likelihood of early post-smolt sexual maturation (jacking) in the all-male populations we found individuals that were homozygous for the early maturing genotype (97%) were more likely to enter puberty than individuals that were homozygous for the late maturing genotype (26%). However, the likelihood of jacking within individuals with an early/late heterozygous genotype was higher when the early allele came from the dam (94%) compared to the sire (45%).
The present results show that supermale Atlantic salmon are viable and fertile and can be used as a research tool to study important aspects of sexual maturation, such as to further explore the sex dependent parental genetic contribution to age at puberty in Atlantic salmon. In addition, we report the production of viable double haploid supermale fish.
Estrogen treatment of mixed sex yolk sac larvae gave rise to one sexually mature hermaphrodite with a male genotype (XY) that was used to produce both self-fertilized offspring and androgenetic double haploid (dh) offspring following egg activation with UV treated sperm and pressure shock to block the first mitotic division. There were YY supermales among both offspring types, which were crossed with dh females. Between 1 and 8% of the putative all-male offspring from the eight crosses with self-fertilized supermales were found to have ovaries, and 95% of these phenotypic females were also genetically female. None of the offspring from the one dh supermale cross had ovaries. When assessing the general contribution of the vgll3 locus on the likelihood of early post-smolt sexual maturation (jacking) in the all-male populations we found individuals that were homozygous for the early maturing genotype (97%) were more likely to enter puberty than individuals that were homozygous for the late maturing genotype (26%). However, the likelihood of jacking within individuals with an early/late heterozygous genotype was higher when the early allele came from the dam (94%) compared to the sire (45%).
The present results show that supermale Atlantic salmon are viable and fertile and can be used as a research tool to study important aspects of sexual maturation, such as to further explore the sex dependent parental genetic contribution to age at puberty in Atlantic salmon. In addition, we report the production of viable double haploid supermale fish.
摘要：
养殖的大西洋鲑鱼是全球最具经济意义的水产养殖产品之一。养殖雄性的早期性成熟代表了该行业的重大挑战，并且与vgll3基因型有关。然而,帮助研究这一主题的工具，如全雄性和克隆鱼，仍然缺乏。目前为期6年的研究检查了大西洋鲑鱼是否可能全雄性生产，具有异形性染色体的物种（雄性为XY，女性XX)，并且如果可以应用全雄性鱼进一步探索vgll3对早期成熟可能性的贡献。
混合性卵黄囊幼虫的雌激素处理产生了一个具有雄性基因型（XY）的性成熟雌雄同体，该雌雄同体用于在卵激活后产生自受精的后代和雄激素双单倍体（dh）后代紫外线处理的精子和压力休克以阻止第一次有丝分裂分裂。两种后代中都有YY超雄，与dh雌性杂交。在八个杂交中，有1％至8％的推定的全雄性后代与自体受精的超雄性被发现有卵巢，这些表型女性中有95％也是遗传女性。一个dh超雄十字架的后代都没有卵巢。在评估vgll3基因座对全男性人群中早熟后性成熟（顶起）的可能性的一般贡献时，我们发现早熟基因型纯合的个体（97％）比早熟基因型纯合的个体（26％）更有可能进入青春期。然而,与父系(45%)相比,早期等位基因来自大坝(94%)时,具有早期/晚期杂合基因型的个体发生顶升的可能性更高.
目前的结果表明，超雄性大西洋鲑鱼是可行和肥沃的，可以用作研究性成熟的重要方面的研究工具，例如，进一步探索大西洋鲑鱼青春期年龄的性别依赖父母遗传贡献。此外,我们报告了可行的双单倍体超雄性鱼的生产。
混合性卵黄囊幼虫的雌激素处理产生了一个具有雄性基因型（XY）的性成熟雌雄同体，该雌雄同体用于在卵激活后产生自受精的后代和雄激素双单倍体（dh）后代紫外线处理的精子和压力休克以阻止第一次有丝分裂分裂。两种后代中都有YY超雄，与dh雌性杂交。在八个杂交中，有1％至8％的推定的全雄性后代与自体受精的超雄性被发现有卵巢，这些表型女性中有95％也是遗传女性。一个dh超雄十字架的后代都没有卵巢。在评估vgll3基因座对全男性人群中早熟后性成熟（顶起）的可能性的一般贡献时，我们发现早熟基因型纯合的个体（97％）比早熟基因型纯合的个体（26％）更有可能进入青春期。然而,与父系(45%)相比,早期等位基因来自大坝(94%)时,具有早期/晚期杂合基因型的个体发生顶升的可能性更高.
目前的结果表明，超雄性大西洋鲑鱼是可行和肥沃的，可以用作研究性成熟的重要方面的研究工具，例如，进一步探索大西洋鲑鱼青春期年龄的性别依赖父母遗传贡献。此外,我们报告了可行的双单倍体超雄性鱼的生产。
