数种昆虫5S rRNA结构特点的比较

比较已知结构的昆虫5S rRNA的核苷酸顺序,发现同科、同目的昆虫比不同科、不同目的昆虫有较少的核苷酸差别.根据Kimura和Ohta(1972)提出的经验公式,绘制了数种昆虫的系统发育图.结果表明,从分子进化得到的结论和经典分类基本上是一致的.根据DeWachter等(1982)提出的二级结构模型,归纳分析这些昆虫5S rRNA,发现保守位点与半保守位点(同一位点仅出现二种核苷酸残基)之和几乎占整个5S rRNA分子的100%.

THE STRUCTURAL CHARACTERISTICS OF 5S rRNA FROM SEVERAL INSECT SPECIES

After comparing all the known sequences of eleven 5S rRNAs from insects, we find there are fewer nucleotide differences in the species f rom the same family or same order as compared with those from different families or orders. The 5S rRNA structures of insects display high homology; aside from the conserved sites possessed by all eukaryotes, they have special sites of their own and the sum of the conserved and semiconserved sites (with only two different nucleotide residues in the same position) in the structure are nearly 100% (Fig. 3). We also, make a phylogenetic tree using the empirical formula proposed by Kimura and Ohta (1972).. The results indicate that the conclusions drawn from molecular evolution are basically consis-tant with those from conventional classification.