@misc{oai:niigata-u.repo.nii.ac.jp:00005475,
 author = {田之村, 秀樹},
 month = {Mar},
 note = {Marbling characterized by the amount and distribution of intramuscular fat in a cross section of musculus longissimus muscle is one of the economically important traits of beef cattle (JMGA, 1988). High levels of marbling improve the palatability and acceptability of beef by affecting the taste and tenderness of the meat (Busboom et al., 1993; Boylston et al., 1995; Matsuishi et al., 2001). Thus, there is great interest in gaining a better knowledge on the molecular architecture of marbling and in generating new opportunities for more effective marker-assisted selection. I applied the integrative approach combining mapping and expression pro filing data to our marbling study using a rat model, Otsuka Long-Evans Tokushima Fatty (OLETF) rat, and Japanese Black beef cattle. In 2nd Chapter, I have established a method for measuring intramuscular fat accumulation. The method is that three or more sections(6 μm thick) are collected at intervals of 180 μm from the site of the center of frozen Musculus longissimus, and they are stained with Oil Red 0 to detect the presence of lipid droplets in adipocyte cytoplasm, and the section area, occupied by cells positive for Oil Red 0 staining, are measured in a given area (1 cm2). Further, I compared the amount of intramuscular fat by using F344 and 10 inbred rat (ExHC, LEA, SHC, TM, Wistea, Wistar fatty, WKAH, Zucker, Zucker fatty and OLETF). As a result, OLETF was found to be useful as an animal model of intramuscular fat accumulation., In 3rd Chapter, I reported that a genomic region between D1Wox8 and D1Rat90 on chromosome 1 influences intramuscular fat content, with the OLETF allele acting on an increase in fat content, by QTL analysis using F2 progenies derived from the OLETF and F344 rats. Further, I demonstrated that the QTL on chromosome 1 responsible for intramuscular fat content is located in the ～10-cM genomic region between D1Rat166and D1Rat90, using a congenic strain trapping the OLETF allele of the ～10-cM region on the F344 genetic background in a monogenic context. The QTL region was refined to the ～2.3-cM genomic region, using informative recombinants. Among 46 genes located within the ～2.3-cM region, pancreatic lipase gene involved in intestinal absorption of long-chain triglyceride fatty acids was selected as positional functional candidate for the intramuscular fat QTL, by utilizing gene expression pro filing data of the located genes. The OLETF allele at pancreatic lipase(Pnlip) was found to possess higher mRNA level and longer size in variable number of tandem repeat within the 5’-flanking region than normal alleles. Further, the intramuscular fat accumulation QTL was shown to completely cosegregate with the variable number of tandem repeat at Pnlip, in the informative recombinants. These results suggested that Pnlip gene is possible candidate for the intramuscular fat accumulation QTL. In 4th Chapter, I analyzed association of the single nucleotide polymorphisms (SNPs) in the bovine PNLIP with marbling in Japanese Black beef cattle. I investigated the allele frequency distribution of the single nucleotide polymorphisms (SNPs) in the PNLIP in high-marbled and low-marbled cattle. The frequencies of the rs41648171 C, rs41648172 T, rs41648173 T, rs41648174 C, rs41648176 C, rs41648178 T and rs42104801 T alleles were higher in Japanese Black sires with extremely high predicted breeding value for marbling than in the sires with extremely low one. Further, as compared to the frequencies of the rs41648172 T, rs41648176 C and rs41648178 T alleles in Japanese Black cattle that has been subjected to a strong selection for high marbling, those in Holstein cattle that has not been selected for high marbling were lower. Further, I showed that SNPs in the bovine PNLIP were associated with the predicted breeding value for beef marbling standard number by analyses using a population of Japanese Black beef cattle. I performed two experiments for the association study. I used 101 Japanese Black sires in experiment 1. In experiment 2, 367 paternal half-sib Japanese Black progeny steers produced from a sire homozygous for the SNP in the PNLIP, with dams considered to represent a random sample of the female population, were used. In experience 1, the predicted breeding value for beef marbling standard number was higher in the TT homozygotes at the rs41648172 SNP than in the CC homozygotes at the SNP, and that of the heterozygotes intermediate between those of the two homozygotes. In experience 2, the predicted breeding value for beef marbling standard number was significantly higher in the CT heterozygotes at the rs41648172 SNP than in the CC homozygotes at the SNP. My findings suggest that PNLIP SNPs may be useful for effective marker-assisted selection to increase the levels of marbling in Japanese Black beef cattle., 学位の種類: 博士（農学）. 報告番号: 甲第3930号. 学位記番号: 新大院博（農）甲第133号. 学位授与年月日: 平成26年3月24日, 新大院博（農）甲第133号},
 title = {OLETFラットを用いた筋肉内脂肪蓄積に関わる遺伝子の探索},
 year = {2014}
}