Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell'Università 16, 35020 Legnaro (PD), Italy.
Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell'Università 16, 35020 Legnaro (PD), Italy.
J Dairy Sci. 2022 Nov;105(11):8946-8955. doi: 10.3168/jds.2022-22136. Epub 2022 Sep 7.
The 2 major subvariants of β-casein (A1 and A2), coded by CSN2 gene, have received great interest in the last decade both from the scientific community and the dairy sector due to their influence on milk quality. The consumption of the A1 variant, compared with the A2 variant, has a potential negative effect on human health after its digestion but, at the same time, its presence improves the milk technological properties. The aim of the present study was to compare the best method in terms of time required, costs, and technical engagement for the identification of β-casein A1 and A2 variants (homozygous and heterozygous animals) in milk to offer a reliable service for large-scale screening studies. Two allele-specific PCR procedures, namely RFLP-PCR and amplification refractory mutation system (ARMS-PCR), and one biochemical technique (HPLC) were evaluated and validated through sequencing. Manual and automated DNA extraction protocols from milk somatic cells were also compared. Automated DNA extraction provided better yield and purity. Chromatographic analysis was the most informative and the cheapest method but unsuitable for large-scale studies due to lengthy procedures (45 min per sample). Both allele-specific PCR techniques proved to be fast and reliable for differentiating between A1 and A2 variants but more expensive than HPLC analysis. Specifically, RFLP-PCR was the most expensive and labor-demanding among the evaluated techniques, whereas ARMS-PCR was the fastest while also requiring less technical expertise. Overall, automated extraction of DNA from milk matrix combined with ARMS-PCR is the most suitable technique to provide genetic characterization of the CSN2 gene on a large scale.
β-酪蛋白的 2 个主要亚变种(A1 和 A2)由 CSN2 基因编码,在过去十年中,由于它们对牛奶质量的影响,引起了科学界和奶制品行业的极大兴趣。与 A2 变体相比,A1 变体在消化后对人体健康可能有潜在的负面影响,但同时,它的存在也改善了牛奶的技术特性。本研究旨在比较鉴定牛奶中β-酪蛋白 A1 和 A2 变体(纯合和杂合动物)的最佳方法,从时间、成本和技术投入方面考虑,为大规模筛选研究提供可靠的服务。评估并通过测序验证了两种等位基因特异性 PCR 方法(RFLP-PCR 和扩增受阻突变系统(ARMS-PCR))和一种生化技术(HPLC)。还比较了从牛奶体细胞中手动和自动提取 DNA 的方案。自动 DNA 提取提供了更好的产量和纯度。色谱分析是最具信息量和最便宜的方法,但由于程序冗长(每个样品 45 分钟),不适合大规模研究。两种等位基因特异性 PCR 技术都被证明可以快速可靠地区分 A1 和 A2 变体,但比 HPLC 分析更昂贵。具体而言,RFLP-PCR 是评估技术中最昂贵和最耗时的技术,而 ARMS-PCR 是最快的,同时也需要较少的技术专业知识。总的来说,从牛奶基质中自动提取 DNA 并结合 ARMS-PCR 是大规模提供 CSN2 基因遗传特征的最适合技术。