仿刺参线粒体全基因组序列结构及比较研究

利用已构建的仿刺参cDNA文库得到的线粒体DNA(mtDNA)相关基因序列设计扩增引物,测定了大连仿刺参线粒体基因组全序列,并对其进行了基因构成和进化分析。仿刺参线粒体基因组序列长16 109bp,其基因构成与其他后口动物基本一致,包括37个基因(2个rRNA基因、22个tRNA基因和13个蛋白质编码基因)和3个主要的非编码区。在其37个基因中,ND6、tRNASer(AGN)、tRNAGln、tRNAAla、tRNAVal、TrnaAsp位于L链上,其余均位于H链上。在13个蛋白质编码基因中,除ND1的起始密码子为GTG外,其余均以ATG作为起始密码子;除Cytb以"T"作为终止密码子外,其他蛋白质基因均具有完全的终止密码子,且在已知的棘皮动物线粒体蛋白质基因中,部分基因的起始和终止密码子表现出一定的纲内特异性。比较分析了大连、青岛、威海仿刺参线粒体基因组,三者的基因组成和排列相同,碱基组成相近,蛋白质编码基因的起始和终止密码子完全一致,但存在核苷酸和氨基酸序列的差异。三者的控制区序列存在多个插入/缺失和SNP位点。根据COI、Cytb和ND4计算了三者之间的遗传距离为0.006～0.018,遗传距离分析和系统进化关系分析都显示青岛仿刺参和威海仿刺参的关系较大连仿刺参更近。

Comparative Structure of Complete Mitochondrial Genome in Sea Cucumber Apostichopus japonicus

Complete nucleotide sequence of mitochondrial genome(mtgenome) in sea cucumber(Apostichopus japonicus) was determined by direct DNA sequencing on the PCR products amplified with 7 pairs of primers which were designed on the basis of its partial mitochondrial DNA(mtDNA) sequences from the cDNA libraries of the sea cucumber.The complete sequence of the sea cucumber mtgenome was found to be 16109 bp in length and to contain 37 genes(2 rRNAs,22 tRNAs and 13 protein coding genes) and several non-coding regions.The ND6,tRNASer(AGN),tRNAGln,tRNAAla,tRNAVal,and tRNAAsp genes are encoded on the light strand(L strand),and the remainders are encoded on the heavy strand(H strand).All protein-coding genes have ATG as initiation codon except ND1 using GTG.Most of the protein-coding genes have complete termination codons,while Cyt b has T as termination codon,and the initiation codon and termination codon of some genes showed specificity in the class of echinodermata.The comparison of the mtgenomes in Shandong and Dalian populations of the sea cucumber revealed that the mtgenomes in the three populations were identical in gene feature,order,and the initiation and termination of all protein-coding genes,except for the nucleotides.Some insertions/deletions(indels) and single nucleotide polymorphisms(SNPs) were found in the control region.The genetic distance was ranged from 0.006 to 0.018 among the three populations of sea cucumber.The phylogenetic analysis based on complete genome and amino acids sequence of 13 protein-coding genes indicates that the Qingdao sea cucumber has closer relationship with that from Weihai than from Dalian.