脊椎动物线粒体DNA的基因重排

将GenBank上已公布的321种脊椎动物mtDNA全序列，按纲整理归类，绘制基因排布图并进行比对。比对结果表明：81个物种的mtDNA中观察到基因重排现象，涉及脊椎动物各纲，其中9个物种同时存在基因顺序变化和基因倒置现象，所有的基因重排都涉及tRNA的变化。脊椎动物mtDNA基因顺序变化可分为3类：1)邻接的基因或片段的位置交换；2)接近于控制序列或轻链起始位点的基因或片段的位置变化，有时还伴随着控制序列的倍增；3)I-Q-M区域的变化。所有鸟类、蛇类、鳄类和有袋类的mtDNA具有各自独特的基因排列顺序。基因倒置现象常见于鱼类和哺乳类，且多表现为tRNA从轻链往重链上迁移。本文就这些基因重排现象、发生重排的机制和mtDNA基因重排在系统发生研究中的应用做一简要概述。

Gene Rearrangement of Mitochondrial Genome in the Vertebrate

Up to date,complete mitochondrial genomes of 321 vertebrates are deposited in GenBank.After comparing the sequence data,we summarized the gene arrangements of these species in present study.Of those species,81 have distinct gene rearrangements all involving tRNA genes.Among them,9 gene rearrangements display both gene order variation and gene encoding invertion.All observed gene order changes of vertebrate mtDNAs fall into 3 categories characteristically: exchange of position between nearest neighbor genes or segments; the changes close to control region or the origin of light-strand replication,occasionally accompanying with duplication of control region; or the changes near the region originally characterized as I-Q-M.All birds,snakes,crocodiles and marsupials have their unique gene orders respectively.Gene inversion,another distinguished character of the rearrangement,is commonly indicated by the transfer of tRNA genes from light-strand to heavy-strand,which is more frequently observed in the fish and mammal.Three species from different classes share a complicated inversion phenomenon: all genes encoded by heavy-strand except ND6.For explanation of these rearrangements,two models,"duplication-random deletion" and "recombination",were commonly adopted by scientists.This paper also gives a brief summarization on the mechanism of these models as well as the application of gene rearrangement in phylogenetic studies.