AgResearch, Ruakura Research Centre, Hamilton, New Zealand.
Sci Rep. 2016 Nov 23;6:37607. doi: 10.1038/srep37607.
We have previously generated transgenic cattle with additional copies of bovine β- and κ casein genes. An initial characterisation of milk produced with a hormonally induced lactation from these transgenic cows showed an altered milk composition with elevated β-casein levels and twofold increased κ-casein content. Here we report the first in-depth characterisation of the composition of the enriched casein milk that was produced through a natural lactation. We have analyzed milk from the high expressing transgenic line TG3 for milk composition at early, peak, mid and late lactation. The introduction of additional β- and κ-casein genes resulted in the expected expression of the transgene derived proteins and an associated reduction in the size of the casein micelles. Expression of the transgenes was associated with complex changes in the expression levels of other milk proteins. Two other major milk components were affected, namely fat and micronutrients. In addition, the sialic acid content of the milk was increased. In contrast, the level of lactose remained unchanged. This novel milk with its substantially altered composition will provide insights into the regulatory processes synchronizing the synthesis and assembly of milk components, as well as production of potentially healthier milk with improved dairy processing characteristics.
我们之前已经生成了具有额外的牛β-和κ-酪蛋白基因拷贝的转基因牛。从这些转基因奶牛中通过激素诱导泌乳生产的牛奶的初步特征表明，牛奶成分发生了改变，β-酪蛋白水平升高，κ-酪蛋白含量增加了一倍。在这里，我们报告了通过自然泌乳生产的富含酪蛋白的牛奶的首次深入特征描述。我们分析了高表达的转基因系 TG3 在泌乳早期、高峰期、中期和后期的牛奶成分。额外的β-和κ-酪蛋白基因的引入导致了转基因衍生蛋白的预期表达，并与酪蛋白胶束的大小相关联的减少。转基因的表达与其他乳蛋白表达水平的复杂变化有关。另外两种主要的牛奶成分受到影响，即脂肪和微量营养素。此外，牛奶中的唾液酸含量增加。相比之下，乳糖水平保持不变。这种成分发生实质性改变的新型牛奶将深入了解同步乳成分合成和组装以及生产具有改善乳制品加工特性的更健康牛奶的调节过程。
