Ibeagha-Awemu Eveline M, Prinzenberg Eva-Maria, Erhardt Georg
Department of Animal Breeding and Genetics, Justus-Liebig University, Giessen, Ludwigstrasse 21b, 35390 Giessen, Germany.
J Dairy Res. 2005 Feb;72(1):1-9. doi: 10.1017/s0022029904000445.
The study provides the first comprehensive information on the variability of milk protein genes of Bos indicus and Bos taurus cattle breeds in Cameroon and Nigeria. The investigations indicate a high diversity of milk protein genes for the zebu populations. Of the investigated alleles, 21 out of 29 were observed. The method of single strand conformation polymorphism (SSCP) was a particularly useful technique because it allowed discrimination of alleles, including zebu-specific alleles at the CSN2 (I) and CSN3 (A(I) and H) loci, not separated by protein electrophoretic techniques and also made possible the detection of a further CSN1S1 5' promoter allele (CSNIS1Prom5), which is also zebu-specific. Characterization of CSN1S1Prom5 showed that it was the most variable of all described CSN1S1 promoter alleles. A potential GATA consensus motif is created by mutations in CSN1S1Prom5. Intra-breed diversity measured as mean effective number of alleles was higher in the zebu populations than in the taurine breeds. Of the expected casein haplotypes, 96 out of 320 were present in the studied breeds. 2-C-A-A2-H (CSN1SIProm2-CSN1S1C-CSN1S2A-CSN2A2-CSN3H) and 5-C-A-A2-H were zebu-specific while 1-B-A-A2-B was specific to the taurines. Overall distribution of alleles and haplotypes clearly separated the zebu populations from the taurine breeds. Zebu influence on the taurine breed Namchi was detected through the occurrence of zebu alleles and haplotypes. High variability of milk proteins also means availability of resources for breed development, phylogenetic studies, and conservation and management decisions.
该研究提供了喀麦隆和尼日利亚瘤牛和普通牛品种乳蛋白基因变异性的首个全面信息。调查表明瘤牛群体的乳蛋白基因具有高度多样性。在所研究的等位基因中，观察到了29个中的21个。单链构象多态性（SSCP）方法是一项特别有用的技术，因为它能够区分等位基因，包括在CSN2（I）和CSN3（A（I）和H）位点上瘤牛特有的等位基因，而这些等位基因无法通过蛋白质电泳技术分离，并且还使得检测到另一个CSN1S1 5'启动子等位基因（CSNIS1Prom5）成为可能，该等位基因也是瘤牛特有的。CSN1S1Prom5的特征表明它是所有已描述的CSN1S1启动子等位基因中变异性最高的。CSN1S1Prom5中的突变产生了一个潜在的GATA共有基序。以平均有效等位基因数衡量的品种内多样性在瘤牛群体中高于普通牛品种。在所研究的品种中，320种预期的酪蛋白单倍型中有96种存在。2-C-A-A2-H（CSN1SIProm2-CSN1S1C-CSN1S2A-CSN2A2-CSN3H）和5-C-A-A2-H是瘤牛特有的，而1-B-A-A2-B是普通牛特有的。等位基因和单倍型的总体分布清楚地将瘤牛群体与普通牛品种区分开来。通过瘤牛等位基因和单倍型的出现，检测到瘤牛对普通牛品种南奇的影响。乳蛋白的高变异性也意味着为品种培育、系统发育研究以及保护和管理决策提供了资源。
