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本文利用多对引物,扩增并测定出鲥鱼、太湖新银鱼和大银鱼18S rRNA基因部分序列,其长度均为1206bp,其中太湖新银鱼与大银鱼基因序列完全相同.将3种经济鱼类与GenBank中10种脊椎动物及头索动物文昌鱼的18S rRNA基因同源序列进行比对分析,计算出序列碱基组成、序列间差异百分比和转换/颠换数值.基于18S rRNA基因序列,利用NJ法、ML法和BI法3种聚类方法,以文昌鱼为外群,构建13种脊椎动物的分子系统树,3种方法获得拓扑学结构一致的系统树.系统树包括3大支,一支为哺乳类、鸟类和爬行类共6个物种,一支为两栖类的2个物种,另一支为5种硬骨鱼类.结果表明:鸟类与哺乳类亲缘关系较近,而胡瓜鱼目与鲑形目亲缘关系近于鲱形目.此外,本文还讨论了脊椎动物18S rRNA基因的序列特征.
In this paper, a number of pairs of primers were used to amplify and determine the partial sequences of the 18S rRNA gene of Halibut auratus, Taihu Lake silver carp and big silver carp, all of which are 1206bp in length, The comparison of 18S rRNA gene homology between 10 kinds of economic fish and 10 species of amphioxus and head animal amphioxus from GenBank revealed that the base sequence composition, percentage difference between sequences and conversion / transversion values were calculated based on 18S rRNA The phylogenetic tree of thirteen species of vertebrates was constructed using three clustering methods: NJ, ML and BI, and the phylogenetic tree of thirteen vertebrates, Three large branches, one for mammals, birds and reptiles a total of six species, one for two species of amphibians and the other five species of teleost fish.The results showed that: birds and mammals , While the Scutellariae is closely related to the order of the salmon (Hymenoptera) .In addition, the sequence characteristics of vertebrate 18S rRNA genes are also discussed.