论文部分内容阅读
目的 :了解沙蝰蛇毒 PL A2 分子在进化过程中的特点 ,特别是基因水平上的特点。方法 :采用不加权成对群算术平均法( UPGMA)构建来自沙蝰蛇毒的 5种 PL A2 的分子进化树 ;将 PL A2 c DNA顺序中编码区内的碱基进行两两比较 ,统计和分析编码氨基酸密码的三个碱基不同位置的取代数及同义取代 ( S)和非同义取代 ( N )数目 ;并分别统计和分析这些 PL A2 的二联碱基胞嘧啶 -鸟嘌呤 ( Cp G)和鸟嘌呤 -胞嘧啶 ( Gp C)的数目及分布情况。结果 :1成功地构建了与 PL A2 性质、功能和彼此间关系相符的分子进化树 ;2碱基取代以第 、 位为多 ,同义取代的数目也远低于非同义取代的数目 ,S/ N远小于 1;3编码区内的二联碱基顺序 Cp G出现的频率非同寻常的高 ,Gp C/ Cp G之比为 1.12～ 1.2 5。非编码区内 Cp G则明显受到压抑而数目很少。结论 :沙蝰蛇毒的 PL A2 基因有加速进化的情况发生 ,可能与其基因中异常高的 Cp G出现频率有关
OBJECTIVE: To understand the characteristics of PL A2 molecules in the process of evolution, especially the gene level. Methods: The molecular phylogenetic tree of five PL A2 genes from Acipenser sinensis was constructed by unweighted pairwise arithmetic average (UPGMA) method. The nucleotide sequences in the coding region of PL A2 c DNA sequence were compared and statistically analyzed (S) and non-synonymous (N) substitutions at different positions of the three amino acids coding for the amino acid code; and statistical analysis was performed on these two tandemly labeled cytosine-guanine (Cp G) and guanine-cytosine (Gp C) number and distribution. Results: 1The phylogenetic tree was constructed successfully according to the nature and function of PL A2 and their relationship with each other. The number of synonymous substitutions of 2-base substitutions was more in the first and the second position than in the non-synonymous substitutions, S / N is far less than 1; 3 CpG in the coding region within the coding region appears unusually high frequency, and the ratio of Gp C / Cp G is 1.12-1.25. Cp G was significantly suppressed in the non-coding region with a small number. CONCLUSION: The accelerated evolution of PL A2 gene in C. sinensis may be related to the abnormally high frequency of CpG in its gene