[Study on mitochondrial DNA genetic diversity of some cattle breeds in China].

The complete mitochondrial D-loop sequences, 910 bp in length, in 22 individuals from 8 cattle breeds in China were analyzed. The results showed that A% + T% was about 61.65%. Comparisons of these 22 sequences revealed 66 polymorphic sites, and 5 types of mutation, transition, transversion, insertion, deletion and coexistence site of transition and transversion were observed,with the percentage of 81.82%, 6.06%, 7.57%, 3.03%, 1.52%, respectively. In reference to complete mtDNA D-loop of the European cattle as a control, eight Chinese cattle breeds were classified into 3 groups according to the average percentage of D-loop nucleotide variations. The lowest average percentage of mtDNA D-loop nucleotide variation was in Xizhen cattle, Mongolian cattle, Holstein, Qinchuan cattle with 0.37%, 0.44%, 0.52%, 0.66%, the mediate in Nanyang cattle and Jiaxian cattle with 1.91%, 2.02% and the highest in Jinnan cattle and Yueyang cattle with 4.47%, 4.73%, respectively. The average sequence divergence estimated from D-loop region within breeds and among breeds in China varied from 0.55% - 5.39% and 1.21% - 6.59%, respectively. Comparisons of these 22 sequences revealed 19 mitochondrial haplotypes, the percentage of haplotype was 86.36%, showing that abundant mitochondrial genetic diversity exists in Chinese cattle. The molecular phylogenetic tree of mtDNA D-loop of 8 Chinese cattle breeds was constructed by Neighbor-Joining method. The NJ tree indicated that these mtDNA sequences fell into 3 distinct haplotype groups, it also suggested in molecular level that there were probably 3 maternal origins, of which the main origins of Chinese cattle were from Bos taurus and Bos indicus.

Lei CZ ，Chen H ，Yang GS ，Song LS ，Lei XQ ，Sun WB ，Li RB ，Liu XL ... -  《-》

[Study on mitochondrial DNA D-loop polymorphism in Chinese donkeys].

The mitochondrial DNA (mtDNA) D-loop sequences with 399 bp in 26 individuals from 5 donkey breeds in China were analyzed. Aligned by Clustal W software,the results showed that 23 polymorphic nucleotide sites and only transition with the percentage of 5.76% in 399 bp were observed. In reference to mtDNA D-loop sequences of European domestic donkey as a control, the average percentage of mtDNA D-loop nucleotide variation in 5 Chinese donkey breeds was 1.80%. The average percentages of D-loop nucleotide variation from Liangzhou donkey (LZ), Yunnan donkey (YN), Guanzhong donkey (GZ), Xinjiang donkey (XJ) and Jiami donkey (JM) were 0. 35%, 1.25%, 2.30%, 2.91% and 2.20% respectively. The average sequence divergence estimated from D-loop sequences varied from 0.25% - 5.01% within breeds and 4.51% - 5.51% among breeds, respectively, demonstrating that there existed rather abundant mitochondrial genetic diversity in Chinese donkeys. Comparisons of the 26 sequences revealed 11 mitochondrial haplotypes; the percentage of haplotype was 42.31%. This phenomenon demonstrated that the mitochondrial genetic diversity in Chinese donkey breeds is being reduced. It is urgent to protect the genetic resources of Chinese donkey. The molecular phylogenetic tree of mtDNA D-loop sequences in 5 Chinese donkey breeds,6 sequences of Asian wild ass (Equus asinus kiang, Equus asinus kulan, Equus asinus hemionus;) and 4 sequences of European domestic donkeys from GenBank was constructed by Neighbor-Joining method. It was the first time proved in molecular level that the origin of Chinese donkey breeds was from African wild ass (Equus africanus africanus and Equus africanus somaliensis), not from Asian wild ass as bescribed in the paper.

Lei CZ ，Chen H ，Yang GS ，Sun WB ，Lei XQ ，Ge QL ，Wang ZF ，Lu N ，Gao X ，Hou WT ... -  《-》

Genetic variation of mitochondrial D-loop region and evolution analysis in some Chinese cattle breeds.

The complete mitochondrial D-loop region from 123 individuals in 12 Chinese cattle breeds and two individuals in Germany Yellow cattle breed was sequenced and analyzed. The results were shown as follows: 93 variations and 57 haplotypes were detected, and the average number of nucleotide difference was 22.708, nucleotide diversity (d) was 0.0251 +/- 0.00479, and haplotype diversity (Hd) was 0.888 +/- 0.026, indicating very high genetic diversity in Chinese cattle breeds. In the Neighbor-Joining tree, 13 cattle breeds were divided into two main clades, Bos taurus and Bos indicus; new Clade ? had only one sequence from Apeijiaza cattle breed in Tibet, which was similar to that of yak at a higher level than other cattle breeds, proving the introgression of genes from the yak. The proportions of Bos taurus and Bos indicus were 64.3% and 35.7% respectively in Xigazê Humped cattle breed, and 50.0% and 50.0% respectively in Apeijiaza cattle breed, which revealed that Tibet cattle included Bos indicus haplotypes. The importance of Yunnan cattle in the origin of Chinese cattle was also confirmed based on their abundant haplotypes. Then, a very special haplotype i1 discovered in 27 Chinese cattle breeds, including 11 breeds in this study and 16 breeds in the GenBank, played the role of a nucleus in Chinese zebu and was further discussed. At the same time, the construction of Chinese zebu core group based on haplotype i1 validated the distinct origin of Bos indicus in Tibet, which was different from that of the other cattle breeds with zebu haplotypes in China.

Jia S ，Chen H ，Zhang G ，Wang Z ，Lei C ，Yao R ，Han X ... -  《Journal of Genetics and Genomics》

[Study on mitochondrial DNA genetic polymorphism of some yak breeds in China].

This study determined yak's complete sequence of mitochondrial DNA control region (D-loop) of 35 individuals in 5 yak breeds at the first time. The result showed that the length of D-loop in yak was 891 -895 bp. Content of nucleotide T, C, A, G were 28.5%, 25.3%, 32.5% and 13.7% respectively. There were 55 polymorphic sites (6.16% in total analyzed sites). The transition,transversion and insertion/deletion were found in this region.24 haplotypes was defined in this study, in which haplotype H4 and H6 were major haplotypes of Chinese yak. The distribution of all the haplotypes among the breeds was disequilibrium. The average diversity of haplotypes were 0.9697 +/-0.0180, indicating the abundance of haplotypes of yak's D-loop. The average nucleotide difference and the nucleotide diversity in Chinese yak breeds were 10.936% and 1.231% respectively. Nucleotide divergence and Kimura 2-parameter distance between yak breeds were 0.760% -2.155%, and 0.000-0.029 respectively. The results indicated that the genetic diversity of Chinese yak was very abundant. Analysis of molecular variance and network construction results indicated that there was significant divergence among Chinese yak breeds. The network construction indicated that Chinese yak had been divided into 2 types and had probably 2 maternal origins or 2 domesticated places.

Lai SJ ，Wang L ，Liu YP ，Li XW ... -  《-》

mtDNA diversity and genetic lineages of eighteen cattle breeds from Bos taurus and Bos indicus in China.

In order to clarify the origin and genetic diversity of indigenous cattle breeds in China, we carried out phylogenetic analysis of representatives of those breeds by employing mitochondrial gene polymorphism. Complete cyt b gene sequences, 1140 bp in length, were determined for a total of 136 individuals from 18 different breeds and these sequences were clustered into two distinct genetic lineages: taurine (Bos taurus) and zebu (Bos indicus). In analysis of the cyt b gene diversity, Chinese cattle showed higher nucleotide (0.00923) and haplotype diversity (0.848) than the reports from other studies, and the animals from the taurine lineage indicated higher nucleotide diversity (0.00330) and haplotype diversity (0.746) than the ones from the zebu lineage (0.00136; 0.661). The zebu mtDNA dominated in the southern breeds (63.3-100%), while the taurine dominated in the northern breeds (81.8-100%). Six cattle breeds from the central area of China exhibited intermediate frequencies of zebu mtDNA (25-71.4%). This polymorphism revealed a declining south-to-north gradient of female zebu introgression and a geographical hybrid zone of Bos taurus and Bos indicus in China.

Cai X ，Chen H ，Lei C ，Wang S ，Xue K ，Zhang B ... -  《GENETICA》