Study On Genetic Diversity Of MHC-Ⅱ In Equine

Mongolian horse is one of good horse resources in China, hence it will be protected because of its some good qualities including resisting chilliness, good endurance, strong antidisease and getting on well with others easily. It has become a jolly valuable gene library of genetic resourses, so it will have inneglectable meaning of economy and society. But at present, some study about equine genetics was quite weakness at present. MHC(Major Hiscompatibility Complex) played main roles in animal antidisease aspects, so it had been one of important study tasks. In my paper, the genetic polymorphisms of 300 samples of seven horse breeds investigated for exon2 of MHC-DRA, DQA, DRB and DQB by PCR-SSCP and direct sequencing, it would provide important experiment gist in order to posting ELA (Equine Leukocyte Antigen) genetic characteristics. There are results as below:1 Every exon 2 of 4 functional genes had polymorphism in ELA-â…¡. The exon 2 of ELA-DRB had greatest polymorphism in four loci because of 27 percent SNPs, in other words, there had 1 nucleotide variance in every 3.7 nucleotide; the second was exon 2 of ELA-DQB and the frequency of SNPs 23.7%, so 1 nucleotide variance in every 4.2 nucleotide; the SNPs frequency of ELA-DRB exon 2 was 21 percent; and rarely polymorphism of ELA-DRA exon 2 because of only 2.4 percent of the SNPs frequency.2 Nucleotide variance types of four loci namely exon 2 of ELA-DRA, DQA, DRB and DQB were all transition and transversion. Three loci were almost transition and coden variation of first and second were more excessive than the third coden except that exon 2 of ELA-DRA had equal frequency in transition and transversion and equal variation at the first, second codens and third codens. Only 1 insert/deletion was detected at exon 2 of ELA-DQA. Evolution of DRA exon 2 sequences had kept silence, DQB*exon2 was not salience and exon2 of DQA and DRB were salience in Z-test.3 Dominance coden and relative synonymous coden usage of four loci had existed definite otherness, in other words, they had inhomogeneity in exon 2 of ELA-DRA, DQA, DRB and DQB.4 The results of colony genetics showed: The gene of DRA exon2 were in Hardy-Weinberg equilibrium in Thoroughbred horse, Wuzhumuqin horse, Sanhe horse and Baerhu horse four breeds, but not equilibrium in Xinihe horse and Wushen horse. 7...