作　　者： ; ; ; ; ; ; ;

机构地区： 辽宁省海洋水产科学研究院

出　　处： 《中国水产科学》 2011年第2期299-307,共9页

摘　　要： 通过表达序列标签法和cDNA末端快速扩增(RACE)技术,分离和克隆了圆斑星鲽(Verasper variegatus)主要组织相容性复合体(MHC)IIB的全长cDNA序列,该cDNA全长为1144bp,5'UTR(untranslated region)为7bp,3'UTR为450bp,开放阅读框(ORF)长度为687bp,可编码228个氨基酸,包含信号肽、抗原结合域(β1)、IGC区(β2)、跨膜区和胞质区5个结构域。同源分析表明,圆斑星鲽MHCIIB氨基酸序列与其他硬骨鱼具有49%～79%的同源性,与鼠、人、红原鸡和护士鲨的相似性较低,分别为34%、33%、31%和30%。圆斑星鲽MHC ⅡB基因含有5个内含子,与其他硬骨鱼不同,其β2结构域编码区内存在1个109bp的内含子。根据获得的MHC ⅡB基因组序列设计特异性引物,在10尾野生圆斑星鲽中扩增了包括完整内含子1和外显子2的长度约388bp的DNA片段,PCR产物直接测序后发现在270bp的抗原结合域中共有23个位点发生变异,密码子第1位和第2位的变异明显高于第3位。利用荧光定量PCR分析组织表达发现,MHCIIB基因在健康圆斑星鲽9种组织中均有表达,但表达量存在差异,肾的表达量最高,肌肉的表达量最低,肾、心、脾脏和鳃的表达量显著高于肝、皮肤、脑、血和肌肉。本研究旨在为MHC基因家族的遗传进化分析、结构与功能的解析提供基础,同时为圆斑星鲽的分子免疫学和标记辅助育种研究提供参考依据。 Major histocompatibility complex （MHC） plays an important role in the immune response of vertebrates.Its function is to present self and non-self peptide to T-cells receptor.In order to study the function and molecular polymorphism of class Ⅱ genes in teleost,MHC ⅡB was identified from Verasper variegates by expressed sequence tags （ESTs） and rapid amplification of cDNA ends （RACE） approach.The full length cDNA was of 1 144 bp,consisting of 5＇UTR of 7 bp,a 3＇UTR of 450 bp with a poly （A） tail,and an open reading frame （ORF） of 687 bp encoding a polypeptide of 228 amino acids,which contained a signal peptide,a peptide-binding region （β1）,an immunoglobulin-like region （β2）,a transmembrane region and a cytoplasmic region.Phylogenetic analysis demonstrated that the putative V.variegates MHC ⅡB amino sequence showed 30%-79% identity with those of other teleosts and vertebrates.The genomic MHC ⅡB contained 6 exons and 5 introns.An important difference between V.variegates MHC ⅡB and other known class ⅡB genes was that β2 domain-encoding exon was split by an intron of 109 bp in length.There were 23 single nucleotide variable sites in exon 2.Realtime PCR analysis demonstrated that MHC ⅡB was ubiquitously expressed in nine tested tissues,but the expression levels were different.The expression levels in kidney,heart,spleen and gill were significantly higher than those in liver,skin,brain,blood and muscle.

关 键 词： 圆斑星鲽 基因结构 多态性 组织特性表达

领　　域： [生物学]