Genetic analysis of a closed herd of Japanese Black cattle in Tajima district using DNA polymorphisms

为有效利用优质田岛牛封闭畜群对日本黑牛进行遗传改良，采用DNA多态性分析方法对该畜群的遗传构成进行了研究。该分析也适用于亲子鉴定。用M13噬菌体DNA探针对该牛群中42个科的牛进行了DNA指纹鉴定。利用一些限制性内切酶（如Hae III.2）鉴定每个家族的亲缘关系。2 .对遗传相似水平(X)与关系系数(Y)进行线性回归，得到Y = 1.149X - 0.026，相关系数极显著，表明DNA指纹技术可用于估算牛的关系系数。基于DNA指纹图谱的聚类分析表明，鹿群大致分为两类。这一结果主要取决于两个波段（小卫星座）的频率。以牛脂蛋白酶cDNA为探针，对牛的限制性内切片段长度多态性（RFLP）进行了检测。1.3kb探针（5′-半含开放阅读框）与5种限制性内切酶（如Pst i）结合得到不同类型的RFLP，每种限制性内切酶的RFLP类型彼此密切相关，表达为A和B单倍型，这表明所有RFLP类型都是连锁的。结果表明，a型和B型RFLP是共显性遗传的。116头日本黑牛分为AA（15头）、AB（65头）和BB（35头）3组，基因频率分别为0.418 （A单倍型）和0.582 （B单倍型）。

To utilize a closed herd of 'Tajima cattle' having high quality beef for genetic improvement of Japanese Black cattle effectively, genetic constitution of the herd was investigated by using DNA polymorphism analysis. The analysis was also applied to parentage identification.1. DNA fingerprinting was examined with a M13 phage DNA probe in the cattle of 42 families extracted from the herd. The parentage of each family was identified by using some restriction endonucleases such as Hae III.2. A linear regression of Genetic Similarity level(X) estimated from DNA fingerprints on relationship coefficient(Y) yielded the equation, Y = 1.149X - 0.026, with highly significant correlation coefficient,indicating that DNA fingerprinting could be applied to estimate the relation coefficient in cattle.3. Cluster analysis based on banding patterns in DNA fingerprints showed that the herd is roughly divided into two groups. This result depended mainly on the frequencies of two bands(minisatellite loci).4. Using bovine cDNA of lipoprotein lypase as a probe, restriction fragment length polymorphisms(RFLP) have been examined in the herd. The 1.3kb probe(5'-half containing open reading frame) gave distinctive RFLPs with 5 restriction enzymes such as Pst I. Types of RFLP being given with each restriction enzyme were closely related to each other and expressed as haplotypes A and B, which suggests all RFLP types are linking. It was shown that Aand B RFLP types are codominantly inherited. Heifers of 116 Japanese Black of the herd were classified into 3 groups, AA(15 heads), AB(65) and BB(35), with the gene frequencies of 0.418 (haplotype A) and 0.582 (B).