【作者】 李永香；

【导师】 李宏；

【作者基本信息】 内蒙古大学 ， 理论物理， 2005， 硕士

【摘要】 本论文共分三部分: 第一部分通过对大肠杆菌编码序列中同义密码子重复序列的研究,分析了同义密码子重复序列与全部编码序列中密码子使用的差异:发现部分密码子在同义密码子重复序列中的使用与在全序列中的使用存在很大的差异;同义密码子4重复片段中相同密码子重复有明显的位置偏好,在同义密码子重复序列中,部分密码子的使用与基因表达水平有关。 第二部分以6种模式生物闪烁古生球菌、枯草杆菌、大肠杆菌、酿酒酵母、线虫和拟南芥基因组中编码序列所翻译的氨基酸序列为样本,研究氨基酸重复序列中氨基酸的使用情况。给出了不同长度氨基酸重复片段数目的分布规律以及与生物进化的关系,得到了氨基酸重复序列中氨基酸含量随联体长度的变化趋势,以及氨基酸联体最大长度的分布与氨基酸疏亲水、体积和极性的关系。 第三部分通过上述6种生物基因组中编码序列的分析,得到关于密码子在同义密码子重复序列中的一些基本性质。结果表明一部分密码子在同义密码子重复序列中的使用与其在全编码序列中明显不同。给出了密码子的联体能力,发现密码子的联体能力各不相同,尤其对于同一个碱基构成的密码子,它们的联体能力低。在同义密码子重复序列中相同的密码子重复片段有非常明显的位置偏好。最后讨论了这些性质与基因组进化的关系。更多还原

【Abstract】 In the first part, based on the synonymous codon repeat sequences of E.coli coding sequences, the difference of codon usage is analyzed between synonymous codon repeat sequences and all coding sequences. Compared with all of the coding sequences, we find that the codon usage has distinct difference for some codons in synonymous codon repeat sequences; the same codon repeats have the position bias in 4 synonymous codon repeat segments; some codons’ usage is correlated with the gene expression levels in synonymous codon repeat segments.In the second part: based on the amino acid sequences which translated by coding sequence in six genomes, which are Archaeoglobus fulgidus Bacillus subtilis Escherichia coli Saccharomyces cerevisiae Caenorhabditis elegans andArabidopsis thaliana, the amino acid usage in amino acid repeat sequences is discussed. The distribution of amino acid repeat segment numbers with its repeat lengh is given. We find that the distributions are correlated with genome evolution and the amino acid content is changed with the amino acid repeat lengh. Furthermore, we find that the maximum lenghs of amino acid repeat are affected by the hydrophobicity and hydrophilicity and amino acid volume as well as the polarity of amino acid.In the third part, by using the coding sequences of the six genomes (shown above), some basic characters about the codon usage in synonymous codon repeat sequences are analyzed. The results show that some codons’ usage in synonymous codon repeat sequences is different from the codon usage in all coding sequences; and the characteristic of codon repeat ability is given. We find that codon repeat ability is different, especially, for same base repeat codons, its repeat ability is low. There is distinct position bias for the same codon repeat segments in synonymous codon repeat sequences. Finally, we discuss the relationship of those characters with genome evolution.更多还原