Characterization of the genetic polymorphism linked to the ?-casein A1/A2 alleles using different molecular and biochemical methods

摘要

The 2 major subvariants of 0-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 0-casein A1 and A2 variants (homozygous and heterozygous animals) in milk to offer a reliable service for large-scale screening studies. Two and amplification refractory mutation system (ARMSPCR), 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. Chromatoallele-specific PCR techniques proved to be fast and reliable for differentiating between A1 and A2 variants RFLP-PCR was the most expensive and labor-demanding among the evaluated techniques, whereas ARMSexpertise. Overall, automated extraction of DNA from of the CSN2 gene on a large scale.