Leshin M
Proc Natl Acad Sci U S A. 1985 May;82(9):3005-9. doi: 10.1073/pnas.82.9.3005.
Male chickens with the henny feathering trait have a female feathering pattern. In two henny-feathered breeds, the Sebright bantam and the Golden Campine, the synthesis of estrogen is increased as a consequence of increased activity of aromatase, a cytochrome P-450 enzyme that converts androgen to estrogen. The activity of the enzyme is elevated in tissue slices and in cultured fibroblasts from heterozygous and homozygous birds of both breeds. In contrast, aromatase activity is very low in extraglandular tissues from control chickens and is undetectable in fibroblasts cultured from these tissues. The current studies show that two agents known to alter gene expression--5-azacytidine and sodium butyrate--markedly induce expression of aromatase activity in Sebright and Campine fibroblasts but have no effect on aromatase activity in fibroblasts from wild-type chickens. Induction of aromatase is specific since two other microsomal enzymes in chicken fibroblasts--one, a component of the aromatase enzyme complex and the other a cytochrome P-450 oxidase distinct from the aromatase--are not significantly affected by these agents. Further study of this unique mutation should provide insight into the mechanisms by which genes are switched to an uninducible state during differentiation.
具有雌羽性状的雄性鸡呈现出雌性的羽毛形态。在两个具有雌羽特征的品种——塞布赖特矮脚鸡和金色坎皮恩鸡中，由于芳香化酶活性增加，雌激素的合成也随之增加。芳香化酶是一种细胞色素P-450酶，可将雄激素转化为雌激素。在这两个品种的杂合子和纯合子鸟类的组织切片以及培养的成纤维细胞中，该酶的活性均有所升高。相比之下，对照鸡的腺外组织中芳香化酶活性非常低，并且从这些组织培养的成纤维细胞中检测不到该酶活性。目前的研究表明，已知的两种可改变基因表达的物质——5-氮杂胞苷和丁酸钠——能显著诱导塞布赖特和坎皮恩成纤维细胞中芳香化酶活性的表达，但对野生型鸡的成纤维细胞中的芳香化酶活性没有影响。芳香化酶的诱导具有特异性，因为鸡成纤维细胞中的另外两种微粒体酶——一种是芳香化酶复合物的组成成分，另一种是与芳香化酶不同的细胞色素P-450氧化酶——不受这些物质的显著影响。对这种独特突变的进一步研究应能深入了解基因在分化过程中转变为不可诱导状态的机制。
