摘要
本文对噬菌体ΦX174基因组的核苷酸频率进行了细致的分析。蛋白质编码基因中核苷酸在各密码位点上的分布是不随机的,且其分布模式在各基因间非常相似,可能是该基因组的特点。本文提出1个基于位点×碱基3×4表的统计量,可以揭示编码区存在额外信息这一事实,也可甩于判定1个未确定读码框架是否是基因。二联体偏差分析发现二联体组合是非随机的,且其特点在基因间具有相似性,在3个位点上也没有明显差异,说明在DNA序列的组成变化和分子替代过程中,DNA水平上的约束起着很重要的作用。
Detailed analysis was carried out on the nacleotide frequencies in the genome of bacterio-phage φX174. In coding regions the distribution of four nucleotides at the three codon sites was highly non-random, and the patterns were conspicuously similar among the genes, implying that it might be a feature of the genome. An index e, which was based on the x2 statistics of the site by base 3×4 table, was introduced to reveal he extra information embedded in the coding region, and also to discriminate between coding and non-coding open reading frames. Doublet deviation analysis showed that deviation patterns were not significantly related to the codon sites in coding regions, and were also very similar in different genes. Possible mechanisms of suoh similarity are discussed.
关键词
核苷酸频率
病毒
基因组
Bacteriophage φX174, Nuc eotide frequencies, Doublet deviation
