Carotenoid pigments produce most red, orange and yellow colours in vertebrates. This coloration can serve as an honest signal of quality that mediates social and mating interactions, but our understanding of the underlying mechanisms that control carotenoid signal production, including how different physiological pathways interact to shape and maintain these signals, remains incomplete. We investigated the role of testosterone in mediating gene expression associated with a red plumage sexual signal in red-backed fairywrens (Malurus melanocephalus). In this species, males within a single population can flexibly produce either red/black nuptial plumage or female-like brown plumage. Combining correlational analyses with a field-based testosterone implant experiment and quantitative polymerase chain reaction, we show that testosterone mediates expression of carotenoid-based plumage in part by regulating expression of CYP2J19, a ketolase gene associated with ketocarotenoid metabolism and pigmentation in birds. This is, to our knowledge, the first time that hormonal regulation of a specific genetic locus has been linked to carotenoid production in a natural context, revealing how endocrine mechanisms produce sexual signals that shape reproductive success.

中文翻译：

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睾酮调节雄性红背细尾鹩莺 (Malurus melanocephalus) 中 CYP2J19 相关类胡萝卜素信号的表达

类胡萝卜素色素在脊椎动物中产生大多数红色、橙色和黄色。这种颜色可以作为介导社交和交配相互作用的诚实质量信号，但我们对控制类胡萝卜素信号产生的潜在机制（包括不同的生理途径如何相互作用以形成和维持这些信号）的理解仍然不完整。我们研究了睾酮在介导红背细尾鹩莺（Malurus melanocephalus）红色羽毛性信号相关基因表达中的作用。在这个物种中，单个种群中的雄性可以灵活地产生红色/黑色的结婚羽毛或类似雌性的棕色羽毛。将相关分析与现场睾酮植入实验和定量聚合酶链式反应相结合，我们发现睾酮部分通过调节 CYP2J19 的表达来介导类胡萝卜素羽毛的表达，CYP2J19 是一种与鸟类类酮类胡萝卜素代谢和色素沉着相关的酮酶基因。据我们所知，这是第一次将特定基因位点的激素调节与自然环境中类胡萝卜素的产生联系起来，揭示了内分泌机制如何产生影响生殖成功的性信号。