Ibeagha-Awemu E M, Prinzenberg E-M, Jann O C, Lühken G, Ibeagha A E, Zhao X, Erhardt G
Institute of Animal Breeding and Genetics, Justus-Liebig-University, Ludwigstrasse 21b, D-35390 Giessen, Germany.
J Dairy Sci. 2007 Jul;90(7):3522-9. doi: 10.3168/jds.2006-679.
The B allele of the bovine alpha (S2)-casein gene (CSN1S2) was characterized at the molecular level and the distribution of zebu-specific milk protein alleles was determined in 26 cattle breeds originating from 3 continents. The CSN1S2B allele is characterized by a C --> T transition affecting nucleotide 17 of exon 3, which leads to a change in the eighth amino acid of the mature protein, from Ser to Phe (i.e., TCC --> TTC). DNA-based methods were developed to identify carriers of CSN1S2B and the other alleles (CSN1S2A, C, and D) at the same locus. CSN1S2B and other zebu-specific milk protein alleles and casein haplotypes are widely distributed in European cattle breeds, particularly those of southeastern origin. Alleles CSN1S2B and CSN3H are important in searching for zebu imprints in European cattle breeds. Diversity estimates at the milk protein loci were highest in the zebus followed by southeastern European taurines. Anatolian Black had the highest number of zebu alleles among European taurines. Common, group, and intergroup haplotypes occurred in the breeds and demonstrated relationships that concurred with developmental histories, genetic makeup, and, in particular, exposed the extent of zebu influence on southeastern European cattle.
对牛α（S2）-酪蛋白基因（CSN1S2）的B等位基因进行了分子水平的特征分析，并确定了源自3个大陆的26个牛品种中瘤牛特异性乳蛋白等位基因的分布情况。CSN1S2B等位基因的特征是外显子3的第17个核苷酸发生C→T转换，这导致成熟蛋白的第八个氨基酸从丝氨酸变为苯丙氨酸（即TCC→TTC）。开发了基于DNA的方法来鉴定CSN1S2B以及同一基因座上其他等位基因（CSN1S2A、C和D）的携带者。CSN1S2B和其他瘤牛特异性乳蛋白等位基因以及酪蛋白单倍型在欧洲牛品种中广泛分布，尤其是那些起源于东南部的品种。等位基因CSN1S2B和CSN3H在寻找欧洲牛品种中的瘤牛印记方面很重要。瘤牛的乳蛋白基因座多样性估计最高，其次是东南欧黄牛。在欧洲黄牛中，安纳托利亚黑牛的瘤牛等位基因数量最多。常见、分组和组间单倍型出现在这些品种中，并显示出与发育历史、遗传构成相符的关系，特别是揭示了瘤牛对东南欧牛的影响程度。
