浒苔(Ulva prolifera)核糖体基因簇单元全长序列的克隆与分析

Cloning and Analysis of Full Length Sequence of Ulva prolifera Ribosomal Gene Cluster Unit

核糖体基因簇单元全长序列对于藻类分子鉴定与分类具有重要意义,而浒苔(Ulvaprolifera)作为形成我国黄海绿潮的主要物种,其核糖体基因簇单元全长序列的克隆还未见研究报道。本研究通过分子克隆技术成功扩增了浒苔的核糖体基因簇单元全长序列。浒苔核糖体基因簇单元全长序列为8948bp,其中18SrDNA1760bp,28SrDNA3259bp,ITS1205bp,5.8SrDNA160bp,ITS2176bp和IGS3388bp。对各部分序列的碱基组成进行分析后,我们发现ITS1,ITS2和IGS序列对胞嘧啶具有明显的偏好性,而18SrDNA和28SrDNA序列对鸟嘌呤具有明显的偏好性。浒苔核糖体基因簇单元全长序列的GC含量为54.12%,其中ITS1、ITS2和IGS序列的GC含量比保守序列的GC含量高,这表明内转录单元间隔区序列和基因间间隔区序列比保守序列变异率更高,进化速率更快。另外,IGS序列中发现大量简单的直接重复序列、串联重复序列、短对称序列和回文序列。浒苔核糖体基因簇单元全长序列可为其分类及分子鉴定提供有效的工具。

The full-length sequence of ribosomal gene cluster is of great significance for the molecular identification and classification of algae. However, Ulva prolifera , a major species forming the green sea tide in the Yellow Sea, in which the complete sequence of ribosomal gene cluster unit has not been reported yet. In this study, the full-length of the ribosomal gene cluster unit of Ulva prolifera has been amplified successfully by molecular cloning technology. The full-length sequence of the Ulva prolifera gene cluster was 8 948 bp, of which 18S rDNA 1 760 bp, 28S rDNA 3 259 bp, ITS1 205 bp, 5.8S rDNA 160 bp, ITS2 176 bp and IGS 3 388 bp. After analyzing the base composition of each part of the sequence, we found that ITS1、ITS2 and IGS sequences have obvious preference for cytosine, while 18S rDNA and 28S rDNA sequences have obvious preference for guanine. The GC content of the full-length sequence of Ulva prolifera gene cluster was 54.12%. The GC content of ITS1,ITS2 and IGS sequences were higher than those of conserved sequences, indicating that the internal transcribed spacer sequences and intergenic sequences have higher variation rate than the conserved sequences, the mutation rate was higher, the evolution rate was faster. In addition, a large number of simply direct repeat sequences, tandem repeats, dyad sequences and palindrome sequence were found in the IGS sequences. In conclusion, the full-length sequence of the ribosomal gene cluster unit of Ulva prolifera can provide an effective molecular tool for the classification and molecular identification of green algae.