15种鱼转铁蛋白cDNA序列密码子使用比较分析

Comparative analysis of codon usage of 15 fish transferrin cDNA sequences

运用DNAman v4.0分析软件,对克隆的鲫鱼血清转铁蛋白cDNA序列与文献中的14种鱼转铁蛋白cDNA序列的同源性、密码子使用频率和密码子使用偏性进行分析,结果表明:鲤形目鱼类Tf的cDNA序列同源性在46%以上,而鲑形目鱼类Tf的cDNA序列同源性在34%-99%之间,变化较大。密码子使用频率越高或使用偏性越小,说明陔密码子编码的氨基酸对蛋白质空间结构的形成和基本生理功能的影响也越重要;在进化上分化时间越早的物种,密码子使用频率和使用偏性的差异较小,反之则较大;在同源性方面,在进化上比较接近的物种,基因的密码子使用频率和使用偏性指标比较接近或基本相同。根据对15种鱼Tf的cDNA序列同源性和密码子分析,推测Tf基因的进化顺序是:鲤形目、鳕形目、鲑形目和鲽形目。

The analysis of the identity, the codon usage frequency and the codon usage preference were made to sequences of Carassius auratus auratus serum transferrin （Tf） cDNA cloned in our laboratory and 14 fish Tf cDNA from reference documentation by DNAman v4. 0. The results show that the identity of Tf cDNA sequences among Cypriniformes fishes is more than 46% and the identity of Tf cD- NA sequences among Oncorhynchus fishes is between 34% - 99% with larger variation. The higher the codon usage frequency or the lower the codon usage preference, the more important the effect of amino acids coded by the codon to form protein space structure and perform basic physiological functions. Furthermore, the earlier the species differentiation time on evolution, the lower the difference of the codon usage frequency and preference and the higher by contraries. Moreover, species with near homology relationship on evolution share the near codon usage frequency and preference index or the similar index. According to the codon usage frequency and the codon usage preference analysis, the evolution sequence of Tf gene, viz. Cypriniformes, Melanogrammus, Oncorhynchus and Paralichthys, were presumed.