草鱼MHC class Ⅰ基因多态性及其与鱼体抗柱形病能力关系分析

Polymorphism of Major Histocompatibility Complex Class Ⅰ Allele and Its Association with Resistance/Susceptibility to Flavobacterium cloumnare in Ctenopharyngodon idellus

用1对引物HMC6-S和MHC6-A分别从草鱼(Ctenopharyngodon idellus)40尾抗病个体和40尾易染个体的基因组DNA中扩增MHC基因片段,扩增产物长度为262bp。在262bp的核苷酸序列中,有50个(19%)多态位点。在其编码的87个氨基酸位点中,有16个多态位点(18.39%),其中有10个位点发生在多肽结合位点上(62.5%)。对核苷酸替代的类型和位点进行分析,发现多肽结合位点的非同义碱基替代率与同义碱基替代率均大于非多肽结合位点的非同义碱基替代率与同义碱基替代率,表明氨基酸替代替换集中出现在多肽结合位点(PBR)上。分析80个个体的测序结果,发现有17种不同的MHC classⅠ等位基因,编码17种不同的氨基酸序列。等位基因A、B、C、D是2个群体共有的,其中等位基因A出现的频率最高,占总样本数量的36.25%;等位基因E、F、G、H、I、P只出现在抗病个体中,等位基因J、K、L、M、N、O、Q只出现在易染个体中。

With a pair of primers HMC6-S and MHC6-A fromCtenopharyngodon idellus MHC gene fragment was amplified genomic DNA of 40resistant Ctenopharynodon idellus individuals and 40susceptible Ctenopharynodon idellus individuals,the length of PCR products of 262bp.Among the PCR products of 262nucleotides,50nucleotide positions were variable(19%).Among the putative 87amino acid positions,16amino acid positions were polymorphic(18.39%) and 10positions occurred in protein binding region(PBR)(62.5%).Comparison between the number of non-synonymous substitutions and synonymous substitutions in PBR and the number in Non-PBR indicated that the selection of amino acid replacement mainly occurred in PBR.Analysis of 80individual sequencing results,found that there are 17different MHC classⅠ alleles,coding 17 amino acid sequence.Analyzed on occurrence percentages of 17different alleles in resistant and susceptible stock,most alleles such as A,B,C,D were commonly found in both stocks(36.25%).In addition,some alleles such as E,F,G,H,I,P only occurred in 40resistant individuals,and alleles J,K,L,M,N,O,Q were only found in 40susceptible individuals.