MHC polymorphism and disease-resistance to Edwardsiella tarda in six turbot(Scophthalmus maximus) families  

作　　者：DU Min CHEN SongLin LIU YanHong NIU BaoZhen YANG JingFeng ZHANG Bo 

机构地区：[1]Key Laboratory for Sustainable Utilization of Marine Fisheries Resources,Ministry of Agriculture,Yellow Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences,Qingdao 266071,China [2]College of Life Sicence and Technology,Honghe University,Mengzi 661100,China [3]College of Aqua-Life Science and Technology,Shanghai Ocean University,Shanghai 200090,China

出　　处：《Chinese Science Bulletin》2012年第25期3262-3269,共8页

基　　金：supported by the National Key Basic Research Program of China (2010CB126303);the Tai Shan Scholar Project of Shandong Province,China

摘　　要：This study examined genetic variation in the major histocompatibility complex(MHC) Class II B gene in turbot(Scophthalmus maximus) by virulent bacterial pathogen challenge.One hundred fry from each of six families were infected with Edwardsiella tarda by intraperitoneal injection.Family mortality ranged from 28.0% to 83.3%.Complete exon 2 and intron 1 sequences of MHC Class II B genes were amplified from five survivor and five non-survivor individuals per family using the clone-sequence method.Thirty-seven sequences from 60 individuals revealed 37 different alleles,25 of which were unique to this study.The 25 unique alleles belonged to 16 major allele types.Nine alleles were used to examine the association between alleles and resistance/susceptibility to disease.Five alleles were present in an individual,suggesting a minimum of three loci or copies of the turbot MHC Class II B gene.The rate of non-synonymous substitution(d N) was 2.30 and 1.58 times higher than synonymous substitution(d S) in the peptide-binding regions(PBR) and non-PBR in whole families,respectively,which suggested balancing selection on exon 2 of the MHC Class II B gene in turbot.One allele,Scma-DBB1*02,was significantly more prevalent in survivor stock than in non-survivor stock(P=0.001).Therefore,this allele might be associated with resistance to bacteria.A second allele,Scma-DBB1*10,was significantly more prevalent in non-survivor stock(P=0.021),and is likely associated with susceptibility to bacteria.This study examined genetic variation in the major histocompatibility complex （MHC） Class II B gene in turbot （Scophthalmus maximus） by virulent bacterial pathogen challenge. One hundred fry from each of six families were infected with Edwardsiella tarda by intraperitoneal injection. Family mortality ranged from 28.0% to 83.3%. Complete exon 2 and intron 1 sequences of MHC Class II B genes were amplified from five survivor and five non-survivor individuals per family using the clone-sequence method. Thirty-seven sequences from 60 individuals revealed 37 different alleles, 25 of which were unique to this study. The 25 unique alleles belonged to 16 major allele types. Nine alleles were used to examine the association between alleles and re- sistance/susceptibility to disease. Five alleles were present in an individual, suggesting a minimum of three loci or copies of the turbot MHC Class IIB gene. The rate of non-synonymous substitution （di） was 2.30 and 1.58 times higher than synonymous substitution （ds） in the peptide-binding regions （PBR） and non-PBR in whole families, respectively, which suggested balancing selection on exon 2 of the MHC Class IIB gene in turbot. One allele, Scma-DBB1 ＊02, was significantly more prevalent in survi- vor stock than in non-survivor stock （P=0.001）. Therefore, this allele might be associated with resistance to bacteria. A second allele, Scma-DBBI＊IO, was significantly more prevalent in non-survivor stock （P=0.021）, and is likely associated with suscepti- bility to bacteria.

关 键 词：迟钝爱德华氏菌 基因多态性 大菱鲆 MHC 家庭 鱼苗 主要组织相容性复合体 抗病性 

分 类 号：S943[农业科学—水产养殖]