高原娟姗牛β-酪蛋白A2纯合基因型的筛选鉴定

Screening and identification of homozygous genotypes ofβ-casein A2 from the plateau jersey cattle

为了筛选出A2A2基因型娟姗牛,组建A2型奶牛育种核心群,为A2牛奶的开发应用奠定基础。从云南欧亚乳业公司鹤庆有机牧场核心群选取385头娟姗牛进行尾静脉采血,提取血液中基因组DNA,检测浓度和纯度后,将提取的DNA进行PCR扩增并送公司测序,同时对血清中β-酪蛋白的含量进行检测。经不同公司各自使用不同引物进行检测,结果一致。在所有娟姗牛中,检测到3种基因型:A2A2基因型198头、A1A1基因型29头、A1A2基因型158头;3种基因型奶牛分别占51.43%、7.53%和41.04%,A2基因频率达71.95%。娟姗牛β-酪蛋白的平均含量为5.58μg/mL,A2A2型和A1A2型奶牛的β-酪蛋白含量均显著低于A1A1型奶牛(P<0.05),但是A2A2型和A1A2型奶牛之间则无统计学差异(P>0.05)。结果表明,通过DNA测序检测突变位点核苷酸能够鉴定出A2A2基因型娟姗牛,β-酪蛋白含量测定不能分辨出A2A2型和A1A2型娟姗牛。与ELISA蛋白检测方法相比,DNA测序法具有快速准确、成本较低等优点,可作为牛群分型的理想方法。

To screen out A2A2 genotype Jersey cattle and establish the core breeding group of A2 dairy cows,and lay the foundation for the development and application of A2 milk.In this experiment,385 Jersey cattle were selected from the core group of Heqing Organic Ranch of Yunnan Eurasia Dairy Company for tail vein sampling,and genomic DNA was extracted from the blood.After detecting the concentration and purity,the extracted DNA was amplified by PCR and sent to the company for sequencing.Meanwhile,the content ofβ-casein in serum was detected.Different primers were used by different companies respectively,and the results were consistent.Three genotypes were detected in all Jersey cattle:198 with A2A2 genotype,29 with A1A1 genotype and 158 with A1A2 genotype;The three genotypes accounted for 51.43%,7.53%and 41.04%,respectively,and the frequency of A2 gene was 71.95%.The average content ofβ-casein was 5.58μg/mL,and theβ-casein content of A2A2 and A1A2 type cows was significantly lower than that of A1A1 type cows(P<0.05),but there was no significant difference between A2A2 type cows and A1A2 type cows(P>0.05).The A2A2 genotype could be identified by DNA sequencing,but the A2A2 genotype and A1A2 genotype could not be distinguished byβ-casein content determination.Compared with ELISA,DNA sequencing method has the advantages of fast,accurate and low cost,and can be used as an ideal method for cattle typing.