Sexual dimorphism often results from hormonally regulated trait differences between the sexes. In sex-role-reversed vertebrates, females often have ornaments used in mating competition that are expected to be under hormonal control. Males of the sex-role-reversed Gulf pipefish (Syngnathus scovelli) develop female-typical traits when they are exposed to estrogens. We aimed to identify genes whose expression levels changed during the development and maintenance of female-specific ornaments. We performed RNA-sequencing on skin and muscle tissue in male Gulf pipefish with and without exposure to estrogen to investigate the transcriptome of the sexually dimorphic ornament of vertical iridescent bands found in females and estrogen-exposed males. We further compared gene expression patterns to identity differentially expressed genes between males and females to generate a list of genes putatively involved in the female secondary sex traits of bands and body depth. A detailed analysis of estrogen-receptor binding sites demonstrates that estrogen-regulated genes tend to have nearby cis-regulatory elements. Our results identified a number of genes that differed between the sexes and confirmed that many of these were estrogen responsive. These estrogen-regulated genes may be involved in the arrangement of chromatophores for color patterning, as well as in the growth of muscles to achieve the greater body depth typical of females in this species. In addition, anaerobic respiration and adipose tissue could be involved in the rigors of female courtship and mating competition. Overall, this study generates a number of interesting hypotheses regarding the genetic basis of a female ornament in a sex-role-reversed pipefish.

中文翻译：

---

海湾尖嘴鱼雌性第二性征的雌激素反应转录组

性二态性通常是由两性之间激素调节的性状差异引起的。在性别角色倒转的脊椎动物中，雌性通常有用于交配竞争的装饰品，这些装饰品预计会受到荷尔蒙控制。性别角色反转的海湾尖嘴鱼 (Syngnathus scovelli) 的雄性在暴露于雌激素时会发展出雌性典型特征。我们旨在确定在女性特定装饰品的开发和维护过程中表达水平发生变化的基因。我们对暴露于和未暴露于雌激素的雄性海湾尖嘴鱼的皮肤和肌肉组织进行了 RNA 测序，以研究在雌性和暴露于雌激素的雄性中发现的垂直虹彩带的性别二态装饰的转录组。我们进一步将基因表达模式与男性和女性之间的差异表达基因进行了比较，以生成假定涉及带和身体深度的女性第二性征的基因列表。对雌激素受体结合位点的详细分析表明，雌激素调节基因往往具有附近的顺式调节元件。我们的结果确定了许多在性别之间不同的基因，并证实其中许多基因对雌激素有反应。这些受雌激素调节的基因可能参与用于颜色模式的色素细胞的排列，以及肌肉的生长，以实现该物种雌性典型的更大的身体深度。此外，无氧呼吸和脂肪组织可能与雌性求爱和交配竞争的严密性有关。全面的，