Molecular evolutionary study on the amphibian mitochondrial genomes

在这项研究中，我们确定了完整的核苷酸序列的蛙蛙黑斑蛙和rhacophorid蛙Buergeria buergeri线粒体DNA。这些青蛙的基因内容，核苷酸组成和结肠的使用符合典型的脊椎动物模式。然而，由于在D环区域中积累了冗长的重复序列，这些物种拥有迄今为止研究的所有脊椎动物中最大的线粒体基因组（黑斑蛙，17，804 bp ; Buergeria buergeri，19，959 bp）。在两栖动物物种（非洲爪蟾、蝾螈和螈）基因组织的比较中，四个tRNA基因和ND 5基因在B线粒体DNA中的定位。buergeri从非洲爪蟾、蝾螈和螈共有的常见脊椎动物基因排列中分离出来。B中tRNA基因的独特位置。buergeri的基因与蛙类共有，表明tRNA基因的重排发生在蛙类和刺囊蛙的共同祖先谱系中。另一方面，ND 5基因的新位置似乎已经出现在一个谱系，导致rhacophorids（和其他密切相关的类群）后，蛙类分歧。基于所有线粒体基因核苷酸序列数据的系统发育分析也支持基因重排途径

In this study we determined the complete nucleotide sequences of the mitochondrial DNA of the ranid frog Rana nigromaculata and the rhacophorid frog Buergeria buergeri. The gene content, nucleotide composition, and colon usage of these frogs conformed to those of typical vertebrate patterns. However, due to an accumulation of lengthy repetitive sequences into the D-loop region, these species possess the large mitochondrial genomes among all the vertebrates examined so far (Rana nigromaculata, 17,804 bp ; Buergeria buergeri, 19,959 bp). In a comparison of gene organizations among amphibian species (Xenopus, salamanders and a caecilian), the positioning of four tRNA genes and the ND5 gene in the mtDNA of B. buergeri diverged from the common vertebrate gene arrangement shared in Xenopus, salamander and caecilian. The unique positions of the tRNA genes in B. buergeri are shared by ranid frogs, indicating that the rearrangements of the tRNA genes occurred in a common ancestral lineage of ranids and rhacophorids. On the other hand, the novel position of the ND5 gene seemed to have arisen in a lineage leading to rhacophorids (and other closely related taxa) after ranid divergence. Phylogenetic analysis based on nucleotide sequence data of all mitochondrial genes also supported the gene rearrangement pathway