Sex Dev. 2019;13(4):212-220. doi: 10.1159/000506344. Epub 2020 Mar 11.
In birds, the female is heterogametic (ZW) and the male homogametic (ZZ). The small W chromosome comprises only 28 protein coding genes (homologues to Z chromosome counterparts) and a number of repeat regions. Here, we report our analysis of one of these genes, BTF3 (basic transcription factor 3), which exhibits differential expression during gonadogenesis. We measured RNA levels of both Z and W homologues and BTF3 protein levels in male and female gonads during development of the chicken embryo. In addition, BTF3 RNA and protein levels were compared in female gonads (ovary) and in female gonads following treatment to induce sex reversal (testis). Combined BTF3 RNA levels were higher in female gonads than male gonads, while BTF3-Z was expressed at similar levels in males and females. Surprisingly, BTF3 protein levels were higher in male gonads than female gonads at embryonic day 6 (E6), suggesting translational rather than transcriptional regulation. BTF3 protein was expressed in both somatic and germ cells and was restricted to the medulla of the developing ovary in females and the sex cords of the developing testis in males. In addition, in gonadal sex-reversed females, RNA and protein levels of BTF3 were similar to those normally found in male gonads, suggesting that BTF3 expression correlated with the gonadal phenotype.
在鸟类中，雌性是异型配子（ZW），雄性是同型配子（ZZ）。小 W 染色体仅包含 28 个蛋白质编码基因（与 Z 染色体的对应物同源）和一些重复区域。在这里，我们报告了对其中一个基因 BTF3（基本转录因子 3）的分析，该基因在性腺发生过程中表现出差异表达。我们测量了鸡胚胎发育过程中雄性和雌性性腺中 Z 和 W 同源物以及 BTF3 蛋白水平的 RNA 水平。此外，我们比较了雌性性腺（卵巢）和经诱导性别反转处理的雌性性腺（睾丸）中的 BTF3 RNA 和蛋白水平。BTF3 RNA 水平在雌性性腺中比雄性性腺高，而 BTF3-Z 在雄性和雌性中的表达水平相似。令人惊讶的是，BTF3 蛋白水平在胚胎第 6 天（E6）时在雄性性腺中高于雌性性腺，表明是翻译而非转录调控。BTF3 蛋白在体细胞和生殖细胞中均有表达，并局限于雌性卵巢的髓质和雄性睾丸的性索中。此外，在性腺性别反转的雌性中，BTF3 的 RNA 和蛋白水平与通常在雄性性腺中发现的水平相似，这表明 BTF3 表达与性腺表型相关。
