The complete mtDNA D-loop regions of Japanese and Korean cattle were analyzed for their mtDNA variations and genetic relationships. Sequencing the 30 Higo substrain and 30 Tosa substrain of Japanese Brown, respectively 12 and 17 distinct Bos haplotypes were identified from 77 polymorphic nucleotide sites. In order to focus on the relationships among Japanese and Korean cattle, two types of phylogenetic tree were constructed using individual sequences; first, a neighbor-joining tree with all sequences and second, reduced median networks within each Japanese and Korean cattle group. The trees revealed that two major mtDNA haplotype groups, T3 and T4, were represented in Japanese and Korean cattle. The T4 haplogroup predominated in Japanese Black and Japanese Brown cattle (frequency of 43.3-66.7%), while the T3 haplogroup was predominant (83.3%) and T4 was represented only twice in the Korean cattle. The results suggested that the mitochondrial origins of Japanese Brown were Japanese ancient cattle as well as Japanese Black in despite of the considerable introgression of Korean and European cattle into Japanese Brown.

Differences of meat qualities between Japanese Black and Holstein have been known in Japan, however, the causative proteins and/or the genetic background have been unclear. The aim of this study was to identify candidate proteins causing differences of the meat qualities between the two breeds. Using technique of two-dimensional gel electrophoresis, protein profiling was compared from samples of the longissimus dorsi muscle and subcutaneous adipose tissue. Five protein spots were observed with different expression levels between breeds. By using LC-MS/MS analysis and Mascot program, three of them were identified as ankyrin repeat protein 2, phosphoylated myosin light chain 2 and mimecan protein. Subsequently, we compared the DNA coding sequences of three proteins between breeds to find any nucleotide substitution. However, there was no notable mutation which could affect pI or molecular mass of the proteins. The identified proteins may be responsible for different characteristics of the meat qualities between Japanese Black and Holstein cattle.

In order to distinguish Korean cattle (Hanwoo) beef from the imported beef from Australia in Korean markets, DNA markers based on PCR-RFLP from mitochondrial genes and SRY gene were applied. A total of 2,826 beef samples comprising 1,495 Hanwoo and 1,331 foreign cattle breeds were obtained in Korea. An 801 bp fragment of the SRY gene on the bovine Y chromosome, a 343 bp fragment of ND4 gene and a 528 bp fragment of ND5 gene in the bovine mtDNA were amplified by PCR and digested with three restriction enzymes, MseI, HpyCH 4 III and Tsp509I, respectively. The results showed that Bos taurus (T) type was the majority in Hanwoo by combining three markers (99.5%). However, 78.2% of Bos indicus (I) type was observed in the imported beef samples. These results indicated that three markers used in this study will be used as valuable markers for discriminating imported beef against Hanwoo.

Kuchinoshima cattle are unique feral cattle in Kuchinoshima Island in Kagoshima prefecture. We genotyped 54K SNPs for Kuchinoshima cattle, Japanese Black, Japanese Brown and Japanese Holstein using high density SNP chip to estimate genetic diversity and genetic structure in Kuchinoshima cattle.Average minor allele frequency in Kuchinoshima cattle was lower (0.089) than those of the other populations (0.181-0.251). Ratio of monomorphic SNPs for each chromosome in Kuchinoshima cattle ranged from 47.7% (BTA24) to 72.3% (BTA20). Subsequently, we investigated expected heterozygosity in each chromosome, and observed six monomorphic regions longer than 5 Mb, especially, the longest region extended 12.80 Mb. This study revealed the extremely low genetic diversity of Kuchinoshima cattle, due to founder effect derived from a few ancestral individuals and genetic drift caused by small population with below 100 animals lasting for a long time in Kuchinoshima Island.Nihon Chikusan Gakkaiho 87 (3), [219][220][221][222][223][224][225][226] 2016