摘要
应用NCBI数据库和计算机分析软件对农业部淡水鱼类种质资源与生物技术重点开放实验室克隆的鲫鱼(Carassiusauratus)转铁蛋白的cDNA序列以及GenBank序列数据库中的27种转铁蛋白及其同源类似物cDNA序列的同源性进行了比较。结果表明:不同种属和来源的转铁蛋白cDNA的同源性均在30%以上;物种分化时间越早,其转铁蛋白基因的同源性越低,相反则越高;不同种属和不同来源转铁蛋白cDNA的进化并不同步,而是由不同途径分别进化的。根据同源性比较结果绘制出它们的系统发育进化树。转铁蛋白基因的进化顺序推测是:微生物转铁蛋白类似物基因、昆虫转铁蛋白基因、黑素转铁蛋白基因、卵转铁蛋白基因、乳转铁蛋白基因、鸟类血清转铁蛋白基因、鱼类血清转铁蛋白基因、哺乳类血清转铁蛋白基因。对cDNA序列的密码子使用频率和密码子使用偏性进行分析,结果表明:密码子使用频率越高或使用偏性越小,说明该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。
The sequence homology among crucian carp(Carassius auratus)transferrin cDNA cloned in authou’s laboratory and 27 species transferrin or the homology analogs cDNAs from GenBank sequence database were compared by using NCBI database and computer analysis software.The results showed that the homology among Tf cDNAs from different species, genus and resources is over 30%.The earlier the differentiation time of species, the lower the homology of Tf gene.The evolution of Tf cDNAs from different species, genus and resources would be done by different ways respectively without the same pace.The evolution phylogeny tree based on the homology comparison was drawn.The train of Tf evolution was conjectured: microorganism homology analog genes, insect Tf, MTf, OTf, LTf and STf of bird, fish and mammal.The code usage frequency and preference of 28 species transferrins and homology analogs’ cDNAs were analyzed.The results showed that the higher the code usage frequency or the lower the code usage preference, the more important the effect of amino acids coded by the code to form protein space structure and perform basic physiologic functions.Furthermore, the earlier the species differentiation time in evolution, the lower the difference of the code usage frequency and preference.Moreover, species with near homology relationship in evolution share near code usage frequency and preference index or similar index.
出处
《长江大学学报（自然科学版）》
CAS
2005年第2期43-49,共7页
Journal of Yangtze University(Natural Science Edition)
基金
农业部"948"国际引进项目资助(983094)
