PCR based analysis of single nucleotide polymorphsim in beta-casein A1 and A2 gene of bovine in Bangladesh

Abstract

In the present study "PCR-based analysis of single nucleotide polymorphism in beta-casein A1 and A2 gene of bovine in Bangladesh" was conducted to differentiate between beta-casein-containing types A1 and A2. Casein contributes80% of the bovine milk protein and has four fractions (alpha S1-CN, alpha S2-CN, beta-CN, and k-CN). Beta casein contributes 25-35% of milk protein and many variants reported in various cattle breeds (A1, A2, A3, B, C, D, E, F, G, H1, H2 and I). The beta-casein variants A1 and A2 differ in the position of 67thamino acid, the substitution of proline in type A2 with Histidine(in A1) is primarily due to the replacement of nucleotide "C" with nucleotide "A" in the corresponding position of nucleotide. For the detection of polymorphsim of A1, A2 beta-casein gene from genomic DNA, thirty cattle (including both local and cross-bred) were selected. Allele-Specific PCR and Amplification Created Restriction Site PCR amplified the beta-casein gene. AS-PCR, ACRS-PCR and subsequent agarose gel electrophoresis could differentiate between A1, A2 types of beta-casein genes in these animals. The results of the screening showed three animal genotypes in these 30 animals. The number of animals with genotypes A1A1, A2A2 and A1A2 are 5, 13 and 12 respectively. The A2 and A1 allele frequencies are 0.63 and 0.37 respectively.