Department of Animal and Aquacultural Sciences, CIGENE, Norwegian University of Life Sciences, Box 5003, 1430 As, Norway.
J Dairy Sci. 2010 Sep;93(9):4340-50. doi: 10.3168/jds.2009-2854.
The Norwegian dairy goat population has a high frequency of a CSN1S1 (alphaS1-casein) haplotype with negative effects on protein and fat content. It is characterized by a single point deletion in exon 12 of CSN1S1, leading to a truncated protein and hence a low content of alphaS1-casein in the milk. This haplotype together with another haplotype with a deletion in exon 9 are called "weak" haplotypes. "Strong" haplotypes, on the other hand, have positive effects on important milk production traits. We show that expression of CSN1S1 in the mammary gland of lactating goats is significantly lower in animals with 2 weak haplotypes. Moreover, the effects of defective alleles were not detected in animals having 1 strong and 1 weak haplotype. Expression levels of other genes in the casein cluster were not affected by the CSN1S1 haplotypes investigated. Milk samples from goats with 2 weak haplotypes could be distinguished from the other milk samples using Fourier transform infrared (FTIR) spectroscopy and partial least squares discriminant analysis (PLS-DA). The PLS-DA components were related to spectra of pure caseins and whey proteins, hence FTIR has a potential for identifying milk samples with low alphaS1-casein content and different protein composition. The results indicate that FTIR-based measurements can be incorporated into breeding plans, or for selection of milk samples with high casein content, which in turn may improve cheese-making properties of the milk.
挪威乳用山羊群体中 CSN1S1（αS1-酪蛋白）单倍型的频率很高，对蛋白质和脂肪含量有负面影响。该单倍型的特征是 CSN1S1 外显子 12 中的单点缺失，导致蛋白质截短，从而使牛奶中的 αS1-酪蛋白含量降低。这种单倍型与另一种在 9 号外显子缺失的单倍型一起被称为“弱”单倍型。另一方面，“强”单倍型对重要的产奶性状有积极影响。我们表明，在泌乳山羊的乳腺中，CSN1S1 的表达在具有 2 个弱单倍型的动物中显著降低。此外，在具有 1 个强单倍型和 1 个弱单倍型的动物中，没有检测到缺陷等位基因的影响。酪蛋白簇中其他基因的表达水平不受所研究的 CSN1S1 单倍型的影响。使用傅里叶变换红外（FTIR）光谱和偏最小二乘判别分析（PLS-DA），可以将具有 2 个弱单倍型的山羊的牛奶样本与其他牛奶样本区分开来。PLS-DA 成分与纯酪蛋白和乳清蛋白的光谱相关，因此 FTIR 具有识别低 αS1-酪蛋白含量和不同蛋白质组成的牛奶样本的潜力。结果表明，基于 FTIR 的测量可以纳入育种计划，或用于选择具有高酪蛋白含量的牛奶样本，这反过来又可以改善牛奶的奶酪制作特性。
