河川沙塘鳢线粒体基因组重排机制及分子标记筛选

Mitochondrial gene rearrangement and molecular marker selection for Odontobutis potamophila

采用引物步移法PCR扩增,获得全长为16846 bp的河川沙塘鳢(Odontobutis potamophila)线粒体全基因组DNA(mt DNA),并对其基因结构、重排机制及在系统发育中的应用进行了分析。研究结果:(1)河川沙塘鳢mt DNA由37个基因和1个非编码控制区组成;除ND6和8个t RNA外,其他基因都编码在重链(H)上;t RNA基因因发生滑移重排(shuffling),将经典的线粒体基因组HSL(t RNAHis–t RNASer–t RNALeu)排列变成了SLH(t RNASer–t RNALeu–t RNAHis)排列,造成在t RNALeu与t RNAHis、ND4与t RNASer之间分别插入了320 bp和42 bp的两个"匿名区"。(2)检测的112种鲈形目(Perciformes)鱼类中,仅有13种(11.61%)发生了mt DNA基因重排现象,而沙塘鳢属的中华沙塘鳢(O.sinensis)、平头沙塘鳢(O.platycephala)与河川沙塘鳢的基因重排位置一致,揭示其可能是沙塘鳢属鱼类进化过程中的一个重要分子"标签"。(3)筛选得到的两个分子标记ND4和ND5基因,适合用于虾虎鱼亚目(Gobioidei)鱼类科阶元水平的系统发育关系的重建。

The river sleeper, Odontobutis potamophila （Perciformes, Odontobutidae）, is a small demersal freshwa-ter goby and has recently been considered a promising candidate for aquaculture in China. However, until now there has been limited genetic information regarding O. potamophila. In this paper, the complete mitochondrial genome （mtDNA） of O. potamophila was obtained by primer-walking PCR amplification, and the mtDNA length was 16846 bp. Then, mtDNA structure, gene rearrangement mechanism, and application in phylogenetic recon-struction were analyzed. The mtDNA of O. potamophila contained 37 genes （13 protein-coding genes, two rRNAs, and 22 tRNAs） and non-coding control regions. In addition to ND6 and eight tRNAs （tRNAGln, tRNAAla, tRNAAsn, tRNACys, tRNATyr, tRNASer, tRNAGlu, and tRNAPro）, all other components were encoded on the heavy strand. All protein-coding genes initiated with the typical ATG sequence except CO I （with GTG） and ATP6 （with ATA）. These 13 protein-coding genes had TAA, TA？, and T？as termination codons. Because of shuffling rearrangement of different tRNAs, the classic mtDNA arrangement HSL （tRNAHis？tRNASer？tRNALeu） changed into SLH （TrnaSer？tRNALeu？tRNAHis）. Consequently, 320 bp and 42 bp anonymous regions were inserted between tRNALeu and tRNAHis, and between ND4 and tRNASer, respectively. However, the content of A＋T （55.3%） was higher than that of G＋C （46.7%）, and it was similar to other fish mtDNA. Among the 112 analyzed Perciforme fish species, only 13 （11.61%） experienced mtDNA gene rearrangement. In particular, the gene rearrangement of O. potamo-phila （KF874495） was similar to that of O. platycephala （NC010199） and O. sinensis （KF154120）, which indi-cates that this is an important molecular‘tag’ for the evolution of the Odontobutis. Selection pressure and genetic diversity analyses of the 13 protein-coding genes revealed that ND4 and ND5 might be suitable molecular candi-date markers for reconstructing phylogenetic relationships in the Gobioidei family. In the ML phylogenetic tree for 10 species of Gobioidei based on ND4 or ND5 gene, the three Odontobutis species were most closely related to Perccottus glenii, and this was consistent with traditional morphological classification.