Charlier C, Coppieters W, Farnir F, Grobet L, Leroy P L, Michaux C, Mni M, Schwers A, Vanmanshoven P, Hanset R
Département de Génétique, Faculté de Médecine Vétérinaire, Université de Liége, Belgium.
Mamm Genome. 1995 Nov;6(11):788-92. doi: 10.1007/BF00539005.
While the hereditary nature of the "double-muscling" phenotype (a generalized muscular hypertrophy documented in several cattle breeds) is well established, its precise segregation mode has remained controversial. Both monogenic models (autosomal dominant or recessive) and oligogenic models have been proposed. Using a panel of 213 bovine microsatellite markers, and an experimental pedigree obtained by backing "double-muscled (Belgian Blue) x conventional (Friesian)"1 dams to double-muscle sire, we have mapped a locus on bovine Chromosome (CHr) 2 that accounts for all the phenotypic variance in the backcross generation. This locus, referred to as mh (muscular hypertrophy), has been positioned with respects to a map composed of seven Chr 2-specific microsatellites, at 2 cM from the closet marker. This result confirms the validity in the Belgian Blue population of the monogenic model involving an autosomal mh locus, characterized by a wild-type "+" and a recessive "mh" allele, causing the double-muscling phenotype in the homozygous condition. The linkage relationship between the mh locus and the Chr 2 markers was confirmed in three informative pedigrees collected from the general Belgian Blue Cattle population, reinforcing the notice of genetic homogeneity of the double-muscling trait in this breed. This work paves the way towards marker-assisted selection for or against the double muscling trait, and towards positional cloning of the corresponding gene.
虽然“双肌”表型（在多个牛品种中都有记录的全身性肌肉肥大）的遗传性质已得到充分证实，但其精确的分离模式仍存在争议。单基因模型（常染色体显性或隐性）和寡基因模型都已被提出。我们使用一组213个牛微卫星标记，以及通过将“双肌（比利时蓝牛）×常规（弗里斯兰牛）”1代母本回交至双肌父本获得的实验系谱，在牛2号染色体（CHr 2）上定位了一个位点，该位点解释了回交后代中的所有表型变异。这个位点被称为mh（肌肉肥大），相对于由7个2号染色体特异性微卫星组成的图谱，它位于距离最近标记2厘摩处。这一结果证实了在比利时蓝牛群体中，涉及常染色体mh位点的单基因模型的有效性，该模型的特征是野生型“+”和隐性“mh”等位基因，在纯合状态下导致双肌表型。在从一般比利时蓝牛群体中收集的三个信息量丰富的系谱中，证实了mh位点与2号染色体标记之间的连锁关系，进一步证明了该品种双肌性状的遗传同质性。这项工作为针对或反对双肌性状的标记辅助选择以及相应基因的定位克隆铺平了道路。
