MORECULAR GENETICAL INVESTIGATION OF DOMESTIC ANIMALS AND POULTRY USING HIGHLY POLYMORPHIC MICROSATELLITE DNA

本研究的目的是构建日本鹌鹑的遗传连锁图谱，寻找日本褐牛软骨发育不良的致病基因，研究日本褐牛特定群体的遗传特征。因此，我们分离了包含CA二核苷酸重复的克隆，但这些克隆中的大多数二核苷酸重复被另一序列中断。这些中断的二核苷酸重复序列不太可能是多态的，因此不能用作标记定位。在日本褐牛的特定群体中，软骨发育不良侏儒症是作为常染色体隐性遗传性状遗传的。利用2200个牛微卫星标记和一个父本半同胞家系，包括48只患病动物和28只正常动物，我们研究了牛软骨发育不良的致病基因座和微卫星基因座之间的连锁关系。因此，我们将该基因定位在牛6号染色体的特定区域上。牛6号染色体的区域与人和小鼠染色体上FGFR3基因定位的区域同源。由于FGFR3基因与人类软骨发育不良有关，因此FGFR3基因是牛软骨发育不良的候选基因。大约50%的微卫星标记在群体中是多态的，在牛中是纯合子状态。这些纯合子基因座的很大一部分被发现定位在染色体的特定区域。这些结果表明，微卫星座位可以作为研究家畜种群遗传特征的有用标记。

The aims of the present study are to construct genetic linkage maps of the Japanese quail, to identify gene responsible for chondrodysplasia of Japanese brown cattle, and to characterize genetic feature of the particular population of Japanese brown cattle.To isolate microsatellite DNA of Japanese quail, microsatellite enriched genomic DNA library was screened with dinucliotide repeats. Consequently, we isolate clones containing CA dinucleotide repeats, but the dinucleotide repeats of most of these clone are interrupted by another sequences. These interrupted dinucleotide repeats are not likely to be polymorphic and thus could not be used as marker loci.In a particular population of Japanese brown cattle, a chondrodysplastic dwarfism is inherited as an autosomal recessive trait. By using 2200 bovine microsatellite markers and a paternal half-sib pedigree including 48 affected and 28 normal animals, we investigated linkage between the locus responsible for the bovine chondrodysplasi and microsatellite loci. Consequently, we mapped the locus on a particular region of bovine chromosome 6. The region of the bovine chromosome 6 is homologous to regions of human and mouse choromosomes on which FGFR3 gene is localized. Since this gene is known to be responsible for human chondrodysplasia, the FGFR3 gene is a candidate gene for the bovine chondrodysplasia.Genome wide scanning of the 5 cattle obtained from a particular population of Japanese brown cattle were performed by using microsatellite markers. About 50% of the microsatellite markers, which are polymorphic in the population, were homozygous condition in the cattle. The significant portion of these homozygous loci were revealed to localize on particular region of chromosomes. These findings suggest that the microsatellite loci could be a useful markers for investigating the genetic feature of populations of domestic animals.