Thaller G, Kühn C, Winter A, Ewald G, Bellmann O, Wegner J, Zühlke H, Fries R
Lehrstuhl für Tierzucht, Technische Universität München, Freising, Germany.
Anim Genet. 2003 Oct;34(5):354-7. doi: 10.1046/j.1365-2052.2003.01011.x.
Intramuscular fat content, also assessed as marbling of meat, represents an important beef quality trait. Recent work has mapped a quantitative trait locus (QTL) with an effect on marbling to the centromeric region of bovine chromosome 14, with the gene encoding thyroglobulin (TG) being proposed as a positional and functional candidate gene for this QTL. Recently, the gene encoding diacylglycerol O-acyltransferase (DGAT1), which also has been mapped within the region of the marbling QTL, has been demonstrated to affect the fat content of milk. In the present study, the effects of a 5'-polymorphism of TG and of a lysine/alanine polymorphism of DGAT1 on the fat content of musculus (m.) semitendinosus and m. longissimus dorsi in 55 bovine animals (28 German Holstein and 27 Charolais) has been investigated. Significant effects were found for both candidate genes in both the breeds. These effects seem to be independent of one another because the alleles of the two polymorphisms showed no statistically significant disequilibrium. The DGAT1 effect is mainly on the m. semitendinosus. The TG polymorphism only affects m. longissimus dorsi. However, both intramuscular fat enhancing effects seem to be recessive. The possibility of two linked loci, acting recessively on intramuscular fat content, will require special strategies when selecting for higher marbling scores.
肌内脂肪含量，也可作为肉的大理石花纹来评估，是一项重要的牛肉品质性状。最近的研究已将一个影响大理石花纹的数量性状基因座（QTL）定位到牛14号染色体的着丝粒区域，编码甲状腺球蛋白（TG）的基因被认为是该QTL的位置候选基因和功能候选基因。最近，编码二酰甘油O-酰基转移酶（DGAT1）的基因也被定位在大理石花纹QTL区域内，该基因已被证明会影响牛奶的脂肪含量。在本研究中，对55头肉牛（28头德国荷斯坦牛和27头夏洛来牛）的半腱肌和背最长肌中TG基因5′端多态性以及DGAT1基因赖氨酸/丙氨酸多态性对脂肪含量的影响进行了研究。在两个品种中均发现这两个候选基因具有显著效应。这些效应似乎相互独立，因为这两个多态性的等位基因未显示出统计学上的显著不平衡。DGAT1的效应主要体现在半腱肌上。TG基因多态性仅影响背最长肌。然而，这两种增加肌内脂肪的效应似乎都是隐性的。当选择更高的大理石花纹评分时，两个连锁基因座隐性作用于肌内脂肪含量的可能性需要特殊的策略。
