Research On The Polymorphism Of The Second Exon Of MHC-DRB₃ Gene From 9 Goat Breeds (Groups) In Southwest, China

The research on the polymorphism of the second exon of MHC-DRB₃ gene from 9 goat breeds (groups) in Southwest, China was carried out in our study to use the polymorphism of MHC to compare DZ goat group with other goat breeds(groups) in genetic resources diversity, which would provide fundamental data and scientific basis for the study on genetic structure,genetic relationship with other breeds(groups),rational utilization and protecion of geneic resources of of DZ group in the aspect of molecular level.The bloods samples from the Banjiao goat(BJ),Dazu black goat(DZ),Chuandong white goat(CD),Chengdu grey goat(CM),Yingshan black goat(YS),Jintang black goat(JT),Guizhon white goat(GB),Xiaoxiang goat in southestern Guizhou(XY) ,Matou goat in Hunan(MT) were collected and the whole DNA was extracted with phenol-chloroform.Then the polymorphism of the second exon of MHC-DRB₃ gene were studied by PCR-RFLP with restriction enzyme of Pst I and Hae III.The results were as follows:1. There was a high polymorphism rate for the second exon of MHC-DRB₃ gene in 9 goat breeds(groups).The degree of genetic variation of DZ group was in middle level. A total of three alleles and four phenotypes were found with restriction enzyme Pst I, which two allele were discovered newly,And seven alleles and thirteen phenotypes with HaeIII,which six allele were discovered newly.The x² fitness test of Hardy-weinberg equilibrium state showed that of all goat breeds in study,only XY was in non- equilibrium state in the restriction site with Pst I .The other five goat breeds including DZ,CD, XY, MT were in non- equilibrium state in the restriction site with Hae III. Otherwise, BJ, CD, CM, YS, JTwere in equilibrium state.For DZ,the degree of genetic variation was lower than the four breeds(groups) including XY,CD,BJ andYS,and higher than the four breeds(groups) including HM, JT, GB and CM.2. In the UPGMA tree based on genetic distance showed that the genetic distance of DZ and BJ was nearest,and the four goat breeds(groups) including BJ, DZ, CB, YS were clustered together,which BJ and DZ, CD and YS were clustered together relatively;the other four goat breeds (groups) including XY, MT, JT, GB were clusered together,which XY and MT were clustered together, and then was JT, GB. CM had a low genetic relationship with other breeds(groups) relatively.