Table_5_The Gene Expression Profile of the Song Control Nucleus HVC Shows Sex Specificity, Hormone Responsiveness, and Species Specificity Among Songbirds.XLSX

Singing occurs in songbirds of both sexes, but some species show typical degrees of sex-specific performance. We studied the transcriptional sex differences in the HVC, a brain nucleus critical for song pattern generation, of the forest weaver (Ploceus bicolor), the blue-capped cordon-bleu (Uraeginthus cyanocephalus), and the canary (Serinus canaria), which are species that show low, medium, and high levels of sex-specific singing, respectively. We observed persistent sex differences in gene expression levels regardless of the species-specific sexual singing phenotypes. We further studied the HVC transcriptomes of defined phenotypes of canary, known for its testosterone-sensitive seasonal singing. By studying both sexes of canaries during both breeding and non-breeding seasons, non-breeding canaries treated with testosterone, and spontaneously singing females, we found that the circulating androgen levels and sex were the predominant variables associated with the variations in the HVC transcriptomes. The comparison of natural singing with testosterone-induced singing in canaries of the same sex revealed considerable differences in the HVC transcriptomes. Strong transcriptional changes in the HVC were detected during the transition from non-singing to singing in canaries of both sexes. Although the sex-specific genes of singing females shared little resemblance with those of males, our analysis showed potential functional convergences. Thus, male and female songbirds achieve comparable singing behaviours with sex-specific transcriptomes.

鸣禽两性均可产生鸣唱行为，但部分物种呈现出典型的性别特异性鸣唱程度差异。本研究针对森林织雀（Ploceus bicolor）、蓝顶蓝饰雀（Uraeginthus cyanocephalus）与金丝雀（Serinus canaria）的高级发声中枢 (HVC，调控鸣唱模式生成的关键脑区) 开展转录组性别差异分析，上述三个物种的性别特异性鸣唱水平分别为低、中、高。研究观察到，无论物种特异性的鸣唱表型如何，基因表达水平均存在稳定的性别差异。我们进一步针对以睾酮敏感性季节性鸣唱为特征的金丝雀，对其不同表型的HVC转录组展开研究。通过对繁殖期与非繁殖期的雌雄金丝雀、经睾酮处理的非繁殖期金丝雀以及自发性鸣唱的雌性金丝雀进行分析，我们发现循环雄激素水平与性别是与HVC转录组变异相关的主要变量。对同性金丝雀的自然鸣唱与睾酮诱导鸣唱进行比较后发现，二者的HVC转录组存在显著差异。在两性金丝雀从非鸣唱状态向鸣唱状态转变的过程中，均可检测到HVC内强烈的转录组变化。尽管鸣唱雌性的性别特异性基因与雄性的相似度极低，但本研究分析显示二者存在潜在的功能趋同。综上，雌雄鸣禽通过具有性别特异性的转录组实现了相似的鸣唱行为。