线粒体和核基因密码子的若干统计特征及其关联

Several Statistic Characteristics Derived from Codons of Mitochondrial and Nuclear Genes and Their Relevancy

基于归1000密码子使用频次,从垂直和水平两个方向比较研究了不同进化阶层生物线粒体基因和核基因密码子使用的若干统计特征及其关联.结果表明:线粒体基因密码子多样性、相对分子质量和相对π电子共振能低于相应核基因且变异较大;不同进化阶层生物线粒体基因和核基因归1000密码子的相对π电子共振能呈极显著负相关且两者之和接近定值;真菌-真菌线粒体、植物-植物线粒体、无脊椎动物-无脊椎动物线粒体的密码子使用频次匹配较好;线粒体基因AU含量、密码子第三位碱基AU3s含量高于相应核基因;给出了密码子各位点碱基含量随进化以及在线粒体-核间的变化规律.由于线粒体环境不如核环境稳定,线粒体基因密码子的多个统计特征较核基因在不同进化阶层生物间变异较大,但二者在归1000密码子相对π电子共振能等若干特征方面仍存在明显关联.

Based on frequency of every codon usage in 1000 codons,several stat is tic characteristics of codons used by mitochondrial genes and nuclear genes from different levels of organism and their relevancy have been studied.The results showed that:the codon diversity,the relative molecular weight and the relative πresonance energy in mitochondrial genes were lower than those in nucleus,respe ctively.Since the mitochondrial environment was not steady,biggish variations of these statistic characteristics were observed in mitochondrial genes compared w ith those of in nucleus.As for πresonance energy,a remarkable negative relativi ty was detected between mitochondrial genes and nuclear genes.The codon usage fr equencies of nuclear genes of fungi,plant and invertebrate matched well with tho se of mitochondria genes,respectively.Mitochondrial genes prefered base A/U and codons with A/U at the third position compared with corresponding nuclear genes. The rules of base content at every position of codon have also been summarized from both vertica l and horizontal directions.