两栖动物线粒体基因组结构特征分析

对2007年6月13日以前公布于GenBank上的78种两栖动物的线粒体基因组全序列进行了总结、比较和分析。78种基因组中基因的数量从35~41个不等;根据基因的数量、种类及其排列顺序的差别将其分为22种基因组类型,其进而聚为3组,其中类型4为两栖纲与其它脊椎动物的常见类型,类型8为两栖纲中现生3个目的公有类型。与类型4比较,其余21种线粒体基因组类型涉及基因变动的基因共有18个,其中变动比较多的是tRNA基因,移位、增多和缺失的发生频率都较大,而蛋白编码基因比较稳定,主要是移位。78种两栖动物中,蚓螈目的线粒体基因组均小于18000bps,多数在15000~16000bps;有尾目和无尾目均大于16000bps,其中有尾目多数在16000~17000bps,无尾目的多数在17000~18000bps。

CHARACTERISTICS OF THE AMPHIBIAN MITOCHONDRIAL GENOME

Until June 2007, seventy-eight species of Amphibians' complete sequence of mitochondrial genome were presented in GenBank. The gene numbers in the genomes range from 35 to 41; the 78 mtDNA genomes can be divided into 22 types and further clustered as 3 groups based on the gene number, kind and arrangement. The type 4 is a common type among the class Amphibia and other vertebrate, type 8 is common among the three orders of living Amphibia. On comparing with the common type 4, there are 18 genes presenting change in the rest 21 types, most of them are tRNA genes, and gene replacement, gene increase and gene absence are frequently happened; on the contrary, protein genes are more steady, gene change is mostly of gene replacement. The genome size of Gymnophiona are all smaller than 18000bps and most of them range from 15000 to 16000bps, those of Urodela and Anura are bigger than 16000bps, most of Urodela range from 16000 to 17000bps, most of Anura range from 17000 to 18000bps.