大竹蛏和长竹蛏线粒体基因组的比较研究

Comparative Study of the Mitochondrial Genomes of Solen grandis and Solen strictus

大竹蛏(Solen grandis)和长竹蛏(Solen strictus)是2种重要的经济贝类。对大竹蛏和长竹蛏的线粒体全基因组进行比较分析。结果表明,2种竹蛏的线粒体基因组具有相似的组成结构、AT含量、基因大小和相同的基因排列顺序,然而两者的蛋白质编码基因的序列以及起始、终止密码子存在较大差异。非同义替换率与同义替换率的比值(Ka/Ks)显示,蛋白质编码基因cox1,cox2和cox3承受较强的选择压力,而nad2,nad3和nad6则承受较小的选择压力。2种竹蛏最长非编码区序列并不保守,但都含有发卡结构和(TA)12微卫星序列。长竹蛏最长非编码区中还存在另外一段串联重复序列。结果显示,2种竹蛏线粒体基因组存在明显差异,线粒体基因组可以做为区分大竹蛏和长竹蛏的重要分子标记。

Solen grandis and Solen strictus are important economic shellfish in China. The mitochondrial genomes of S. grandis and S. strictus were compared in this study. Two genomes were similar composition, AT content and gene size, and identical in gene order. In contrast, two genomes were obviously different in gene sequence and type of some start and stop codons. As showed by the ratio of asynonymous to synonymous nucleotide shift （Ka/Ks） in protein-coding genes, genes coxl, cox2 and cox3 received stron- gest selection while genes nad2, nad3 and had6 received least selection. The longest non-coding regions of two genomes were not conservative in evolution~ however they were characterized by some hairpin struc- tures and （TA）12 microsatellite-like elements. In addition, the mitochondrial genome of S. strictus con- tained an extra tandem repeat in its longest non-coding region. The difference between two genomes prom- ised to serve as the markers distinguishing two species.