Treaster Matthew J, McCann Jenny, Solovei Kyra S, Palmieri Ryan J, White Michael A
Department of Genetics, University of Georgia, Athens, GA, 30602.
bioRxiv. 2025 Apr 29:2025.04.28.650899. doi: 10.1101/2025.04.28.650899.
Many taxa have independently evolved genetic sex determination where a single gene located on a sex chromosome controls gonadal differentiation. The gene anti-Mullerian hormone () has convergently evolved as a sex determination gene in numerous vertebrate species, but how this gene has repeatedly evolved this novel function is not well understood. In the threespine stickleback (), was duplicated onto the Y chromosome () ~22 million years ago. To determine whether is the primary sex determination gene, we used CRISPR/Cas9 and transgenesis to show that is necessary and sufficient for male sex determination, consistent with the function of a primary sex determination gene. Despite being indispensable for sex determination, we detected low levels of expression throughout early development. This indicates the mechanism of sex determination is likely unrelated to overall dosage of and its autosomal paralog, . Threespine stickleback have striking differences in behavior and morphology between sexes. The creation of sex reversed lines allow us to investigate the genetic basis of secondary sex characteristics. Here we show one of the classic traits important for reproductive success, male nuptial coloration, is controlled by both Y-linked genetic factors as well as hormonal factors independent of sex chromosome genotype. This research establishes stickleback as a model to investigate how regulates gonadal development and how this gene repeatedly evolves novel function in sex determination. Analogous to the four core genotypes model in house mice, sex-reversed threespine stickleback offer a new vertebrate model for investigating the separate contributions of gonadal sex and sex chromosomes to sexual dimorphism.
许多分类群已经独立进化出遗传性别决定机制，其中位于性染色体上的单个基因控制性腺分化。抗缪勒氏管激素（AMH）基因在许多脊椎动物物种中已趋同进化成为一种性别决定基因，但该基因如何反复进化出这种新功能尚不清楚。在三刺鱼中，AMH基因约在2200万年前复制到Y染色体上。为了确定AMH是否是主要的性别决定基因，我们使用CRISPR/Cas9和转基因技术表明，AMH对于雄性性别决定是必要且充分的，这与主要性别决定基因的功能一致。尽管AMH对于性别决定不可或缺，但我们在整个早期发育过程中检测到其表达水平较低。这表明性别决定机制可能与AMH及其常染色体旁系同源基因的总体剂量无关。三刺鱼在行为和形态上存在明显的性别差异。性反转品系的建立使我们能够研究第二性征的遗传基础。在这里，我们表明，对于繁殖成功很重要的一个经典特征——雄性婚姻色，受Y连锁遗传因素以及独立于性染色体基因型的激素因素控制。这项研究将三刺鱼确立为一个模型，用于研究AMH如何调节性腺发育以及该基因如何在性别决定中反复进化出新功能。类似于家鼠的四核心基因型模型，性反转的三刺鱼为研究性腺性别和性染色体对两性异形的单独贡献提供了一个新的脊椎动物模型。
