漳州西施舌线粒体基因组全序列:腔蛤蜊属(Coelomactra)存在新种的证据

The complete mitochondrial genome of Zhangzhou Coelomactra antiquata : the evidence of a new species in genus Coelomactra (Mollusca : Mactridae)

利用长PCR扩增漳州西施舌线粒体DNA(ZZ-mtDNA),用引物步移法测序,获得线粒体基因组DNA全序列,研究其基因组特点。结合双壳类49个物种线粒体全基因组,分析基因间核苷酸和蛋白质氨基酸序列的差异,构建系统进化树,探讨漳州西施舌系统演化地位。研究结果表明:漳州西施舌线粒体基因组DNA全长17 199bp,A+T含量为64.2%,编码36个基因,其中12个蛋白质编码基因,22个转运RNA基因(tRNAs),2个核糖体RNA基因(lrRNA和srRNA),全部基因均位于重链上,tRNASer为单拷贝,tRNAMet为双拷贝;非编码区占10.9%(1 882bp/17 199bp),其中,主非编码区为882bp,与RZ-mtDNA主非编码区差异明显,另有一个较大(400bp)的非编码区为漳州西施舌特异性非编码区;以双壳纲帘蛤目文蛤属3种贝类、贻贝目贻贝属4种贝类、珍珠贝目牡蛎科的6种贝类为参照,对编码基因的核苷酸序列和蛋白质氨基酸序列进行差异分析显示,漳州西施舌与日照西施舌达到了种间差异水平。线粒体基因组编码的基因、tRNA组成、非编码区均揭示漳州西施舌是腔蛤蜊属的一个新种。

Mitochondrial DNA of Zhangzhou Coelomactra antiquata was obtained by long PCR amplification,and sequenced using primers-walking strategy.Then the phylogenetic tree was built with 49bivalve species to explore the evolutionary status of the Zhangzhou C.antiquata.The results showed that the total length of mitochondrial genome of Zhangzhou C.antiquatais 17 199bp and A＋T content is 64.2%.Thirty-six genes encoding on the same chain were consisted of 12protein genes,22tRNA（one duplication of tRNASer,and two copies of tRNAMet） genes and two rRNA genes（lrRNAandsrRNA）.The nucleotide content of non-coding regions is 10.4%（1 842 bp/17 199bp）,one major non-coding region（MNR）is 882bp,another 400nt non-coding region,which is specific for ZZ C.antiquata,was also found in its mitochondrial genome.Significant differences of MNR between Zhangzhou C.antiquataand Rizhao C.antiquata were observed.As references to three species fromMeretrix（Veneroida）,four species fromMytilus（Mytiloida）,and six species fromCrassostrea（Ptenioida）,the differences of nucleotides and amino acid sequences of protein coding genes revealed that divergence of Zhangzhou C.antiquata and Rizhao C.antiquatareached the level of interspecies difference.The difference of the encoding genes,tRNA composition and the non-coding regions suggest that Zhangzhou C.antiquatashould be a new species of genus Coelomactra.