Phaeocystis globosa核糖体大亚基(28SrDNA)的序列分析与分类学意义

对一株Phaeocystisglobosa的28SrDNA基因序列测定,共得到碱基大小为1795bp的两个序列片段,其中序列一的长度为970bp,序列二的长度为825bp。将Ph.globosa与Ph.antarctica和Prymnesiumpatelliferum同源序列进行对比,发现Ph.globosa与Ph.antarctica仅在序列二中有一个碱基插入/缺失,同源性为99.99%,而与Pr.patelliferum相比,有7处插入/缺失,碱基总变异率为6.13%;研究发现序列一中有一个比较明显的高度保守区和两个高变区;序列二中有两个比较明显的高变区、一个保守区和一个高度保守区。对28SrDNA基因RNA二级结构分析发现,DNA序列保守区在RNA二级结构上也非常保守,与DNA序列分析结果一致,都证明28SrDNA基因只适用于种以上水平的分类研究,不宜用于种间和种下水平的研究。

28SrDNA sequence analysis and taxology significance of Phaeocystis globosa

Two sections of the 28SrDNA gene sequences of Ph.globosa were determined and obtained, their length are 1795bp. Section 1 is 970bp, and section 2 825bp. By comparative analyzing Ph.globosa, Ph.antarctica and Prymnesium patelliferum , there is only one base in the section 2 between Ph.globosa and Ph.antarctica insert/absence and the homologous rate is 99.99%. However, in both section there are seven position insert/absence between Ph.globosa and Prymnesium patelliferum , overall difference rate of both sequence is 6.13%. Compared 28SrDNA gene sequence of Ph.globosa to other biology taxa. There is a obviously high conservation region and two high variance regions in the section, and there are two high variance regions in the section 2, one conservation region and one high conservation region. Analyses of the secondary structure of RNA of 28SrDNA gene showed the conservation region in the DNA sequence is also very conservative in the secondary structure of RNA and both prove that the 28SrDNA gene is not suitable to Phylogenetic analysis in phaeocysitis .