Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia.
Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas.
Pigment Cell Melanoma Res. 2019 May;32(3):381-390. doi: 10.1111/pcmr.12753. Epub 2018 Dec 14.
The chocolate plumage color in chickens is due to a sex-linked recessive mutation, choc, which dilutes eumelanin pigmentation. Because TYRP1 is sex-linked in chickens, and TYRP1 mutations determine brown coat color in mammals, TYRP1 appeared as the obvious candidate gene for the choc mutation. By combining gene mapping with gene capture, a complete association was identified between the chocolate phenotype and a missense mutation leading to a His214Asn change in the ZnA zinc-binding domain of the protein. A diagnostic test confirmed complete association by screening 428 non-chocolate chickens of various origins. This is the first TYRP1 mutation described in the chicken. Electron microscopy analysis showed that melanosomes were more numerous in feather follicles of chocolate chickens but exhibited an abnormal structure characterized by a granular content and an irregular shape. A similar altered morphology was observed on melanosomes of another TYRP1 mutant in birds, the roux mutation of the quail.
鸡的巧克力色羽毛颜色是由于性连锁隐性突变 choc 引起的，该突变稀释了真黑色素的着色。由于 TYRP1 在鸡中是性连锁的，并且 TYRP1 突变决定了哺乳动物的棕色被毛颜色，因此 TYRP1 似乎是 choc 突变的明显候选基因。通过将基因定位与基因捕获相结合，确定了巧克力表型与导致蛋白 ZnA 锌结合域中 His214Asn 变化的错义突变之间的完全关联。通过筛选来自不同来源的 428 只非巧克力鸡的诊断测试证实了完全关联。这是在鸡中描述的第一个 TYRP1 突变。电子显微镜分析表明，巧克力鸡的羽毛毛囊中有更多的黑素体，但表现出一种异常结构，其特征是颗粒状内容物和不规则形状。在另一种鸟类 TYRP1 突变体，鹌鹑的 roux 突变中也观察到了类似的改变形态。
