基于mtDNA全序列的南方大口鲇进化分析

Phylogenetic analysis of Silurus meridionalis based on the complete mitochondrial DNA sequence

【目的】基于线粒体基因组(mtDNA)探讨南方大口鲇在鲇形目中的系统进化地位,为鲇形目鱼类的系统进化研究积累基础资料。【方法】采用参照近缘物种线粒体基因组设计覆盖全基因组引物的方法,设计合成16对引物对南方大口鲇mtDNA进行分段扩增,拼接后获得其mtDNA全序列,对其基因组结构进行初步分析,并基于mtDNA序列对南方大口鲇进行系统进化分析。【结果】南方大口鲇mtDNA全长16 527bp(GenBank检索号为:HM746661),包括2个rRNA基因、22个tRNA基因、13个编码蛋白质基因和1个非编码控制区;序列分析显示,南方大口鲇线粒体基因组结构和基因排列顺序与现已公布的鲇形目鱼类完全一致。系统进化分析表明,南方大口鲇与六须鯰聚为一支,黄颡鱼、瓦氏黄颡鱼、光泽黄颡鱼和越南拟鲿聚为一支,湄公河巨鲶、长臀鮠及斑点叉尾鮰聚为一支,这3支聚在一起后再与牛头鲴及黑躯兵鲶相聚,最后与扬子鳄相聚。【结论】南方大口鲶与鲇形目鲇科鱼类六须鲶的进化地位最为相近。在进行系统发育研究时,应选择合适的基因,以便得到较为可靠的系统发育结果。

【Objective】 The study was conducted to determine the complete mitochondrial genome of Silurus meridionalis,and discuss its evolution in the Siluriformes to provide basic data for the classification of Siluriformes fishes.【Method】 The complete mitochondrial genome of S.meridionalis was obtained by PCR based on 16 primers which were designed on the basis of related species mtDNA sequences.And the genome construction and the phylogenesis were analysed.【Result】 The complete genome is 16 527 bp in length（GenBank Accession：No.HM746661）,including 2 ribosomal RNA genes,22 transfer RNA genes,13 protein-coding genes and a non-coding control region.Sequences analysis showed that the organization and location of genes in the mitochondrial genome of S.meridionalis were consistent with Siluriformes fishes published.The NJ tree clustering maps showed that S.meridionalis and S.glanis were of the same branch,the second branch included Pelteobagrus fulvidraco,Pelteobagrus vachelli and Pelteobagrus nitidus,the third branch included Pangasianodon gigas,Cranoglanis bouderius and Ictalurus punctatus,and three branchs were clustered together.Then this branch was clustered with Liobagrus obesus,Corydoras rabauti and finally Alligator sinensis.【Conclusion】 S.meridionalis is most closely related to Silurus glanis.In order to obtain dependable results,suitable gene should be selected to analyze the phylogenetic relationship.