Concepts of evolutionary biology suggest that morphological change may occur by rare punctual but rather large changes, or by more steady and gradual transformations. It can therefore be asked whether genetic changes underlying morphological, physiological, and/or behavioral innovations during evolution occur in a punctual manner, whereby a single mutational event has prominent phenotypic consequences, or if many consecutive alterations in the DNA over longer time periods lead to phenotypic divergence. In the marine teleost, sablefish (Anoplopoma fimbria), complementary genomic and genetic studies led to the identification of a sex locus on the Y Chromosome. Further characterization of this locus resulted in identification of the transforming growth factor, beta receptor 1a (tgfbr1a) gene, gonadal somatic cell derived factor (gsdf), as the main candidate for fulfilling the master sex determining (MSD) function. The presence of different X and Y Chromosome copies of this gene indicated that the male heterogametic (XY) system of sex determination in sablefish arose by allelic diversification. The gsdfY gene has a spatio-temporal expression profile characteristic of a male MSD gene. We provide experimental evidence demonstrating a pivotal role of a transposable element (TE) for the divergent function of gsdfY. By insertion within the gsdfY promoter region, this TE generated allelic diversification by bringing cis-regulatory modules that led to transcriptional rewiring and thus creation of a new MSD gene. This points out, for the first time in the scenario of MSD gene evolution by allelic diversification, a single, punctual molecular event in the appearance of a new trigger for male development.

中文翻译：

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转座子外化后的等位基因多样化促进gsdf成为黑貂的主要性别决定基因

进化生物学的概念表明，形态变化可能通过罕见的准时但相当大的变化发生，或者通过更稳定和渐进的转变发生。因此，可以询问进化过程中形态、生理和/或行为创新背后的遗传变化是否以准时的方式发生，即单个突变事件具有显着的表型后果，或者是否在较长时间内 DNA 中的许多连续改变导致表型差异。在海洋硬骨鱼、黑貂鱼（Anoplopoma fimbria）中，互补的基因组和遗传研究导致鉴定了 Y 染色体上的性位点。对该基因座的进一步表征导致鉴定出转化生长因子β受体1a（tgfbr1a ) 基因，性腺体细胞衍生因子( gsdf )，作为实现主性别决定 (MSD) 功能的主要候选者。该基因的不同 X 和 Y 染色体拷贝的存在表明黑貂鱼性别决定的雄性异配子 (XY) 系统是由等位基因多样化产生的。gsdfY基因具有男性 MSD 基因的时空表达谱特征。我们提供实验证据证明转座因子 (TE) 对于gsdfY的发散功能的关键作用。通过插入gsdfY启动子区域，该 TE 通过引入cis产生等位基因多样化-导致转录重新布线并因此产生新的MSD基因的调节模块。这首次指出，在 MSD 基因通过等位基因多样化进化的场景中，一个单一的、准时的分子事件出现在男性发育的新触发因素中。