Casas E, Stone R T, Keele J W, Shackelford S D, Kappes S M, Koohmaraie M
US Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933-0166, USA.
J Anim Sci. 2001 Apr;79(4):854-60. doi: 10.2527/2001.794854x.
The objective of this study was to identify quantitative trait loci for economically important traits in two families segregating an inactive copy of the myostatin gene. Two half-sib families were developed from a Belgian Blue x MARC III (n = 246) and a Piedmontese x Angus (n = 209) sire. Traits analyzed were birth, weaning, and yearling weight (kg); preweaning average daily gain (kg/d); postweaning average daily gain (kg/d); hot carcass weight (kg); fat depth (cm); marbling score; longissimus muscle area (cm2); estimated kidney, pelvic, and heart fat (%); USDA yield grade; retail product yield (%); fat yield (%); and wholesale rib-fat yield (%). Meat tenderness was measured as Warner-Bratzler shear force at 3 and 14 d postmortem. The effect of the myostatin gene was removed using phase information from six microsatellite markers flanking the locus. Interactions of the myostatin gene with other loci throughout the genome were also evaluated: The objective was to use markers in each family, scanning the genome approximately every 25 to 30 centimorgans (cM) on 18 autosomal chromosomes, excluding 11 autosomal chromosomes previously analyzed. A total of 89 markers, informative in both families, were used to identify genomic regions potentially associated with each trait. In the family of Belgian Blue inheritance, a significant QTL (expected number of false-positives = 0.025) was identified for marbling score on chromosome 3. Suggestive QTL for the same family (expected number of false-positives = 0.5) were identified for retail product yield on chromosome 3, for hot carcass weight and postweaning average daily gain on chromosome 4, for fat depth and marbling score on chromosome 8, for 14-d Warner-Bratzler shear force on chromosome 9, and for marbling score on chromosome 10. Evidence suggesting the presence of an interaction for 3-d Warner-Bratzler shear force between the myostatin gene and a QTL on chromosome 4 was detected. In the family of Piedmontese and Angus inheritance, evidence indicates the presence of an interaction for fat depth between the myostatin gene and chromosome 8, in a similar position where the evidence suggests the presence of a QTL for fat depth in the family with Belgian Blue inheritance. Regions identified underlying QTL need to be assessed in other populations. Although the myostatin gene has a considerable effect, other loci with more subtle effects are involved in the expression of the phenotype.
本研究的目的是在两个分离出肌肉生长抑制素基因无活性拷贝的家系中，鉴定经济重要性状的数量性状基因座。两个半同胞家系分别由一头比利时蓝牛与MARC III（n = 246）以及一头皮埃蒙特牛与安格斯牛（n = 209）的种公牛繁育而来。分析的性状包括出生重、断奶重和周岁体重（千克）；断奶前平均日增重（千克/天）；断奶后平均日增重（千克/天）；热胴体重（千克）；脂肪厚度（厘米）；大理石花纹评分；背最长肌面积（平方厘米）；估计的肾、盆腔和心脏脂肪含量（%）；美国农业部产量等级；零售产品产量（%）；脂肪产量（%）；以及批发肋部脂肪产量（%）。肉嫩度通过死后3天和14天的沃纳-布拉茨勒剪切力来测定。利用位于该基因座侧翼的六个微卫星标记的阶段信息消除了肌肉生长抑制素基因的影响。还评估了肌肉生长抑制素基因与整个基因组中其他基因座的相互作用：目的是在每个家系中使用标记，在18条常染色体上每隔约25至30厘摩（cM）扫描基因组，不包括先前分析过的11条常染色体。总共89个在两个家系中均具有信息性的标记用于鉴定可能与每个性状相关的基因组区域。在比利时蓝牛遗传家系中，在3号染色体上鉴定出一个与大理石花纹评分显著相关的数量性状基因座（假阳性预期数 = 0.025）。在同一个家系中还鉴定出了提示性数量性状基因座（假阳性预期数 = 0.5），分别为3号染色体上的零售产品产量、4号染色体上的热胴体重和断奶后平均日增重、8号染色体上的脂肪厚度和大理石花纹评分、9号染色体上的14天沃纳-布拉茨勒剪切力以及10号染色体上的大理石花纹评分。检测到有证据表明肌肉生长抑制素基因与4号染色体上的一个数量性状基因座之间存在3天沃纳-布拉茨勒剪切力的相互作用。在皮埃蒙特牛和安格斯牛遗传家系中，有证据表明肌肉生长抑制素基因与8号染色体之间存在脂肪厚度的相互作用，其位置与在比利时蓝牛遗传家系中提示存在脂肪厚度数量性状基因座的位置相似。需要在其他群体中评估鉴定出的数量性状基因座所在区域。尽管肌肉生长抑制素基因有相当大的影响，但其他具有更细微影响的基因座也参与了表型的表达。
