武定乌骨鸡MC1R基因多态性与黑色素沉积的关联研究

The association between MC1R gene polymorphism and melanin deposition in Wuding silky fowl

旨在探究武定鸡乌骨品系和非乌骨品系黑素皮质素受体1(MC1R)基因多态性与黑色素沉积的相关性,以期为后期利用分子遗传学技术选育乌度更深的武定鸡提供理论参考。试验通过测定300日龄武定鸡乌骨品系和非乌骨品系的血浆真黑色素、褐黑色素和碱溶性黑色素含量,分析了MC1R基因外显子的多态位点(SNPs)与黑色素的关系,并检测组织中MC1R基因表达差异。结果发现:武定鸡乌骨品系血浆中3种黑色素指标均高于非乌骨品系。在MC1R外显子区域检测到4个突变位点(T133C、T244C、G460A和C833A),除武定鸡非乌骨品系C833A位点偏离Hardy-Weinberg平衡以外,其余位点均未偏离;武定鸡非乌骨品系G460A位点呈低度多态,其余突变位点均呈中度多态,其中T244C位点CC基因型和G460A位点AA基因型的真黑色素和碱溶性黑色素含量均高于其他基因型,属于优势基因型。此外,武定鸡乌骨品系各组织中MC1R基因表达量均显著高于非乌骨品系,且各组织间的表达趋势为皮肤>肾脏>肝脏>心脏>肌胃>脾脏>腿肌>胸肌。本试验结果表明,MC1R基因T244C位点和G460A位点突变可能会对武定鸡的乌质性状产生影响,推测这2个位点是影响武定鸡乌骨品系和武定鸡非乌骨品系乌度差异的原因之一。

This study was to investigate the correlation between the polymorphisms of melanocortin 1 receptor(MC1R)gene and melanin deposition in the silky bone strain of Wuding chickens and the non-silky bone strain of Wuding chickens,in order to provide theoretical reference for the future cultivation of Wuding chickens with“darker silkiness”by molecular genetics technology.The contents of eumelanin,brown melanin and alkal-soluble melanin in plasma of the silky bone strain and the non-silky bone strain of 300-day-old Wuding chickens were determined.The polymorphic sites of MC1R gene exons of the birds were analyzed by sequencing,and the expression differences of the MC1R gene in their tissues were detected.The plasma indexes of the silky bone strain of Wuding chickens were higher than those of the nonsilky bone strain.Four mutation sites(T133C,T244C,G460A and C833A)were detected in the exon region of MC1R,and none of the sites,except C833A,deviated from the Hardy-Weinberg equilibrium.The contents of eumelanin and alkali-soluble melanin in the CC genotype at T244C and the AA genotype at G460A were higher than those of the other genotypes,and these genotypes belonged to the dominant genotypes.In addition,the expression of the MC1R gene in each tissue of the silky bone strain of Wuding chickens was significantly higher than the non-silk bone strain,and the expression trend among these tissues was in skin>kidney>liver>heart>musogastric>spleen>leg muscle>chest muscles.Mutations at T244C and G460A of the MC1R gene might affect the melanin traits in Wuding chickens.It is speculated that these two loci might be one of the reasons for the difference in“silkiness”between the silky bone strain and the non-silk bone strain of Wuding chickens.