Polymorphism's of mitochondrial DNA and selection of Japanese Black

日本黑牛肉是国内唯一一种能生产出与国外产品相比具有经济竞争力的牛肉的家畜，因为它能生产出高品质的牛肉。生产高质量牛肉的基因尚不清楚。几乎所有的研究都集中在对来自细胞核的基因组DNA的研究上，然而在过去的几年里，我们开始关注来自线粒体的基因组。根据线粒体的d环DNA序列，将日本黑虫分为5类。我们发现，第4类生产的牛肉质量很高。1)为了确定这种线粒体效应是否存在于商业繁殖群体中，将8000多头奶牛按线粒体DNA类型分为5组。由于饲养条件、年季、饲养场等环境因素的影响，线粒体类型的影响尚不明确。但在兵库县，线粒体效应只在28个月大的肥育牛身上观察到。如果D-loop对牛肉生产有一定的生理影响，由于D-loop区域不编码任何蛋白质，那么应该存在与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2只动物，并测定了整个线粒体基因组的DNA序列。我们在16SrRNA上发现了可能影响线粒体蛋白质合成的4型特异性突变。

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.