摘要自GenBank检索到双壳类线粒体基因组，对其进行基因结构比较分析，以揭示线粒体基因组的演化规律，为线粒体基因组在物种演化和鉴定上的应用研究提供资料。结果共获得45个物种线粒体基因组序列，分布于双壳类5个目中。多数种类线粒体基因组大小为15～32 kb。平均 A＋ T ＝62．9％。多数种类基因分布在重链上，而蚌目的基因分布在2条链上；少数种类（蚌目13个、帘蛤目的2个、贻贝目的1个、海螂目的1个，巨蛎属的贝类）的线粒体基因组含有13种蛋白质基因，其余种类为12种，缺少atp8；文蛤属4个种类、巨蛎属中4个种类、蚌目的11个种类、贻贝属中的紫贻贝和地中海贻贝的PCGs、rRNA基因排序在同属内或科内相同；珍珠贝目牡蛎科的10个种类线粒体基因组可分为7种类型；扇贝科海湾扇贝2个线粒体基因组基因结构相似外，其余种类无共享基因块；贻贝科的紫贻贝和海湾贻贝基因结构极相似。绿贻贝的结构独特，co x 2为双拷贝；海螂目的北方钻岩蛤基因结构与其它目的相似性极低。多数双壳类线粒体基因组非编码区占7．64％～40．26％，主非编码区大小为374～4341 nt。基于12种PCGs核苷酸/氨基酸的属内种间最小分歧度分别为0．2～1．0/0～1．0（文蛤属）、0．4～2．0/0～3．2（贻贝属）和1．9～13．9/0～6．4（巨蛎属）。
Abstract：Bivalves mitochondrial genomes (mtDNA ) were retrieved from GenBank , and then the comparative analysis of the genomic structures were conducted to reveal the evolution of mitochondrial genomes in bivalves ,and the application of mitochondrial genome in the evolution and identification of related species. A total of 45 mtDNA sequences obtained ,ranging from 15 to 32 kb ,with average A+T content of 62. 9% ,were distributed in 5 orders in bivalves. Genes of most species were found to be distributed in the heavy chain ,and mitochondrial genes from Unionoida in the 2 chains. A few species (12 species from Unionoida ,2 species from Veneroida ,1 species from Mytiloida ,and 1 species from Myoida , species from oyster Crassostrea) mitochondrial genomes contain 13 protein-coding genes (PCGs) ,and the remainings are comprised of 12 PCGs ,w hich are lack of AT P8 gene. The gene arrangements of PCGs and rRNAs are identical within same genus or family ,including 4 species from Meretrix ,4 species from Crassostrea ,11 species from Unionidae and Margaritiferidae , two species (Mytilus edulis and M. galloprovincialis) from mussel Mytilus. The gene arrangements of 10 mitochondrial genomes from Ostreidae can be divided into 7 types. There were no shared gene blocks in mitochondrial genomes from Pectinidae except similar gene structures were detected in bay scallop Argopecten irradians irradians f arreri(NC_012977)and A. irradians(NC_009687). The mussels Mytilus edulis and M. trossulus from Mytilidae have very similar genomic structures ,and the genomic structure of Musculista senhousia is very special with a duplicated cox2 genes. The gene arrangement of Hiatella arctica from Myoida is very different from other species. The proportions of non-coding regions in mitogenomes are ranged from 7.6%to 40.3% ,the major non-coding region ranging from 374nt to 4341nt in size in bivalves. The minimum divergence is found to be 0.2-1.0/0-1.0 in Meretrix ,0.4-2.0/0-3.2 in Mytilus and 1.9-13.9/0-6.4 in oyster Crassostrea based on nucleotides of PCGs genes/amino acids of proteins.
