Polymorphism's of mitochondrial DNA and selection of Japanese Black

日本黑牛是唯一一种生产出与国外产品具有经济竞争力的牛肉的家畜，因为日本黑牛生产的牛肉品质较高。目前还不知道生产高质量牛肉的基因。几乎所有的研究都集中在细胞核的基因组DNA上，然而，在过去的几年里，我们关注的是线粒体的基因组。根据线粒体D-loop DNA序列，将日本黑分为五类。我们发现，类型4的一组生产出高质量的牛肉。1)为了确定在商业繁殖牛群中是否观察到这种线粒体效应，将8,000头以上的奶牛按线粒体DNA类型分为5组。由于饲养条件、年度季节、饲养场等环境因素的影响，线粒体类型的作用尚不清楚，但在兵库县，线粒体效应仅见于28个月龄育肥的公牛。如果D-loop对牛肉生产有一定的生理影响，因为D-loop区域不编码任何蛋白质，所以应该存在与D-loop类型相协调的D-loop区域以外的其他区域的突变。我们从每种线粒体类型中选择两种动物，测定了线粒体全基因组的DNA序列。我们在16SrRNA中发现了4型特异性突变，这种突变可能会影响线粒体的蛋白质合成。

Japanese black is only one domestic animal which produce economically competitive beef with foreign products, because of producing high grade beef. The genes by which the high quality beef being produced are not yet known. Almost of all researches are concentrated their study on the genome DNA from the nuclei, however, we had paid attention on the genome from mitochondria for past few years. Japanese Black are classified into five groups depending on D-loop DNA sequence of mitochondria. We found that a group, type 4, produce high quality beef. 1)To ascertain if this mitochondrial effect is observed in commercial reproductive herd, cows of more than 8,000 were classified into 5 groups by mitochondrial DNA type. The effect of mitochondrial type is not clear because of environmental effects, such as feeding condition, year season, feedlot etc. But in Hyogo prefecture, the mitochondrial effect was only observed in steers of 28month old finishing. If D-loop has some physiological effects on beef production, as the D-loop region does not code any protein, so that mutations other region than D-loop region, which coordinates with D-loop type should be present. We selected two animals from each mitochondrial type and DNA sequence of whole mitochondria genome was determined. We found type 4 specific mutation in 16SrRNA which may affect on protein synthesis in mitochondria.