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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。
A pair of primers HMC6-S and MHC6-A were used to amplify the MHC gene fragment from genomic DNA of 40 tail-resistant individuals and 40 susceptible individuals of grass carp (Ctenopharyngodon idellus) respectively. The length of the amplified product was 262 bp. In the 262 bp nucleotide sequence, there are 50 (19%) polymorphic sites. There are 16 polymorphic sites (18.39%) among the 87 amino acid sites encoded, of which 10 sites (62.5%) occur at the polypeptide binding site. Analysis of the types and sites of nucleotide substitutions showed that both the nonsynonymous base substitution rate and the synonymous base substitution rate of the polypeptide binding sites were greater than the nonsynonymous base substitution rates of the non-polypeptide binding sites The sense-base substitution rate indicates that amino acid substitution substitutions are concentrated at the polypeptide binding site (PBR). Analysis of the sequencing results of 80 individuals revealed 17 different MHC class I alleles encoding 17 different amino acid sequences. The alleles A, B, C and D were shared by two groups, of which allele A appeared the highest frequency, accounting for 36.25% of the total number of samples. The alleles E, F, G, H, I and P Appears in the disease-resistant individuals, the alleles J, K, L, M, N, O, Q appear only in vulnerable individuals.