苔藓动物主要类群28S rDNA多变区的分子形态分析及其系统学意义

测定了苔藓动物主要代表类群3种苔虫的28S rDNA全序列(3 459～3 613 bp),结合已公布的相关类群的28S rDNA全序列数据,分析了其一级结构特征,并分别绘制了D2、D3和D8区段的二级结构.比较分析结果显示:各类群的全序列总长均超过3 300 bp,GC含量为41.8%～57.7%;D3和D8区段的二级结构保守性较高,D2区差异显著;各区段的长度变化较大,但是,大多都具有相似的主干结构.基于二级结构多变区分子形态学特征的比较基本和基于一级结构的分子系统学结论相吻合,提示它们同样包含着重要的系统发育信息.

28S rDNA MOLECULAR MORPHOLOGY OF THE MAIN BRYOZOAN LINEAGES AND ITS PHYLOGENETIG SIGNIFICANCE

Complete 28S rDNA of three species of representataive bryozoan lineages were amplified and sequenced. Their primary structures, and predicted secondary structures of D2, D3 and D8 domains were compared and analysed combining with those of other three representative species published in GenBank. The results show that each sequence of them is over 3 300 base pairs and their GC contents are from 41.8%- 57.7%; the secondary structures of D3 and D8 domains are relatively conserved, whereas the D2 domain is significantly variable; the sequence lengths varied markedly among them for each D domain, however, their morphological characteristics of the secondary structures are basically the same. The phylogenetic relationships based on the morphological characters of secondary structures are consistent with those based on the primary structures and other features, and this fact shows that the moclecular morphology is also the valuable source for the phylogenetic information.