中国沿海9种红藻hsp70基因序列及系统进化分析

本研究自山东青岛、浙江象山和江苏南通采集共9种红藻样品, 隶属于2纲、5目、6科、8属(据NCBI), 克隆各红藻hsp70 基因, 并对所获序列进行分析。利用特异性引物P1/P3扩增, 得到的目的条带约630 bp, 分析所推导的氨基酸序列发现:所获得片段均位于HSP70的ATPase结构域附近。9种红藻hsp70 序列之间的遗传距离在0.078～0.319之间, 序列相似度在73%～92%之间, 其保守性略低于HSP70蛋白;基因对A或T结尾的密码子表现出很高的偏好性, CGC与TGG这两种密码子在这9种红藻HSP70氨基酸密码子中未出现。上述表明hsp70 及HSP70密码子偏好性可应用于红藻分子系统学研究。基于多物种HSP70构建的进化树可见, Cyanidium caldarium与Cyanidioschyzon merolae strain 10D两种原始红藻的起源早于其他红藻, 紫菜次之, 本研究中9种红藻系统发生符合NCBI的描述。在真菌、藻类和植物中, 营养方式的差异可能是造成HSP70进化树分化的基本原因, 而相同形态类型的物种中, 环境适应是抗逆能力强、遗传结构稳定的物种生物分子进化的重要因素。

Phylogenetic analysis based on hsp70 gene sequences of the nine red seaweeds from Chinese coasts

Nine common species of red seaweeds were collected from the coasts of Qingdao Shandong, Nantong Jiangsu and Xiangshan Zhejiang area, which could be classified into 2 classes, 5 orders, 6 families, 8 genus (according to the NCBI). The hsp 70 genes were amplified by PCR from 9 red seaweeds, phylogenetic analysis were carried out based on the hsp70 gene and HSP 70 protein sequences. The obtained target bands amplified by the primers P1/P3 were about 630bp, which were presumed located near the ATPs domain based on the HSPs sequences analysis The distances of hsp70 sequences within 9 red seaweeds were between 0.078 and 0.319, and the similarities of sequences were between 73% and 92%, which conservation were slightly lower than their HSP70 proteins. The codons ended with A and T were preferred in the hsp70 genes of these 9 red seaweeds while the codons of CGC and TGG were not founded. The results of the phylogenetic analysis of hsp70, 18S rDNA and rbcL sequences in other algae, microbes and plants obtained from GenBank suggested that the origin of the primitive red algae Cyanidium caldarium and Cyanidioschyzon merolae strain 10D were more primordially than the other red algae, while the Pyropia species were followed, and the phylogenesis of the 9 species of red seaweeds studied in this paper were coherent with those described in NCBI. The difference of nutrition mode might be the basic factor of HSP 70 differentiation in fungi, algae and plant, while the adaptation to variable environment was the major factor in biological molecular evolution when the organisms were at the same morphological levels, which made the species much stronger in stress resistance and more stable in genetic structures.