两种鯻科鱼类线粒体16S rRNA基因片段序列分析

Sequencing of Mitochondrial DNA 16S rRNA from Scortum barcoo and Hephaestus fuliginosus

利用PCR技术成功扩增了高体革鯻(Scortum barcoo)和厚唇弱棘鯻(Hephaestus fuliginosus)的线粒体16S rRNA基因序列。通过序列测定,得到791 bp的基因片段,碱基A、T、G、C平均含量分别为31.4%、21.2%、20.5%和26.9%,序列中的A+T含量明显高于G+C的含量,这与其他鱼类的16S rRNA基因片段研究结果相一致。通过序列分析发现,高体革鯻和厚唇弱棘鯻两序列共存在23处碱基变异,其中碱基转换位点20个,碱基颠换位点3个,转换与颠换比率为6.7,没有发现碱基插入与缺失。与从GenBank中查到的3种鯻科鱼类的同源序列比对,邻接法(ne ighbor-join ing)构建亲缘关系树,结果显示,5种鯻科鱼类聚在一起,分为独立的2支,匀鯻和单色匀鯻及花身鯻聚成1支,高体革鯻和厚唇弱棘鯻聚为1支,说明高体革鯻与厚唇弱棘鯻的亲缘关系比较近,而与其他另外3种鯻科鱼类亲缘关系比较远。

Mitochondrial 16S rRNA gene fragments of Scortum barcoo and Hephaestus fuliginosus were amplified via PCR,then the PCR products were purified and sequenced.For 16S rRNA gene fragments,791 bp nucleotide sequences were obtained,and the A,T,G and C average contents in this fragment were 31.4%,21.2%,20.5%,26.9%,respectively.Analysis of this gene fragment indicated that A＋T content were higher than C＋G content,which was similar to the results in other fish.The two sequences showed 23 substituted sites,of which there were 20 transition sites and 3 transversion sites,and the transition/transversion ratio was 6.7,without insertion/deletion site.The result of the phylogenetic tree revealed that the five species clustered together and divided into two branches,Leiopotherapon aheneus,Leiopotherapon unicolor and Terapon jarbua assembled a branch,and Scortum barcoo and Hephaestus fuliginosus assembled another branch,indicating that there was a close relationship between Scortum barcoo and Hephaestus fuliginosus.