中国沿岸几种鲍线粒体16S rRNA基因片段序列比较及鲍属系统发育

用PCR技术克隆耳鲍（Haliolis asinina）、羊鲍（H．ovina）和多变鲍（H．varia）的线粒体16S rRNA基因的片段，并将PCR产物直接进行测序，得到长度530bp左右的片段。将这些序列与杂色鲍（H．diversicolor diversicolor）、九孔鲍（H．diversicolor supertexte）、大鲍（H．gigantea）、盘鲍（H．discus discus）、皱纹盘鲍（Haliotis discus hannai）等5种鲍的相应片段进行序列比较。结果表明，不同种鲍间16S rRNA基因的序列同源性较高，同源性范围为87．36％～90．77％，这说明鲍的这段基因片段在遗传过程中比较保守。序列的A＋T含量约为56．68％，G＋C含量约为43．32％。8种鲍序列的主要核苷酸变异位点集中在1-25bp、240-290bp和320～370bp3个区域。在序列的变异碱基巾，碱基的转换大大多于碱基的颠换，转换与颠换之比达到2．33：1，遗传距离的范围为0．002-0．128。用UPGMA法和NJ法绘制出8种鲍的系统发育树。结论认为，大鲍、皱纹盘鲍和盘鲍之间的遗传差异水平为亚种间的差异水平，台湾产的九孔鲍与大陆沿岸产的杂色鲍之间的差异仅仅是种群间的差异。

Sequence analysis of mitochondrial 16S rRNA gene and molecular phylogeny of eight species of abalones in genus Haliotis

PCR method was adopted for amplification of mitochondrial 16S rRNA gene from three species of abalones(Haliotis),and all of amplicons were sequenced directly.Consequently,three mitochondrial 16S rRNA gene sequences with length of over 530 bp were obtained from the three species of abalones(H.asinina,H.ovina,H.varia).These three sequences were then multialigned and compared with the corresponding sequences of other five species of abalones(H.discus hannai AY146393;H.discus discus AY146392;H.gigantea AY146395;H.diversicolor diversicolor AY146397 and H.diversicolor supertexte AY146396)by GenBank.The results show high homologous among them(the homologous rate ranges from 87.36% to 90.77%).In the 530 bp sequence of mitochondial 16S rRNA gene,A+T rate is about 56.68%,and G+C is about 43.32%.The variation of the sequences focuses on the three regions: 1-25bp,240-290bp and 320-370bp.The pattern of nucleotide substitutions favors transitions over transversions,yielding a transition/transversion ratio of 2.33/1.The genetic distances among the eight species of abalones were calculated and the phylogenetic tree was constructed using Mega 2.0.The results indicate that H.discus hannai,H.discus discus and H.gigantae are closely related and distinguished at subspecies level;H.diversicolor diversicolor and H.diversicolor supertexte are distinguished at population level.