Naveh-Many T, Cedar H
Mol Cell Biol. 1982 Jul;2(7):758-62. doi: 10.1128/mcb.2.7.758-762.1982.
The topographical distribution of 5-methylcytosine on animal and plant cell DNA has been examined with methyl-sensitive restriction enzymes and gel electrophoresis analysis. These DNAs digested with the enzyme HpaII have a partially bimodal size distribution, indicating the existence of clusters of methylated and unmethylated CCGG sites in the DNA. By analyzing the methylation state of all CG moieties in restricted DNA fractions, it was possible to show that these genomes are, in general, arranged as clusters of relatively highly methylated and undermethylated regions. Plant DNA also contains 5-methylcytosine in the prototype sequence C-X-G. Restriction of this DNA with EcoRII revealed that these methyl groups are also distributed in clusters, suggesting that this is a general phenomenon. The undermethylated areas may correspond to the active fraction of the genome.
利用甲基敏感限制性内切酶和凝胶电泳分析,研究了动植物细胞DNA上5-甲基胞嘧啶的拓扑分布。用HpaII酶消化的这些DNA具有部分双峰大小分布,表明DNA中存在甲基化和未甲基化CCGG位点的簇。通过分析限制性DNA片段中所有CG基团的甲基化状态,有可能表明这些基因组通常是作为相对高度甲基化和低甲基化区域的簇排列的。植物DNA在原型序列C-X-G中也含有5-甲基胞嘧啶。用EcoRII对该DNA进行限制性内切显示这些甲基基团也呈簇分布,表明这是一种普遍现象。低甲基化区域可能对应于基因组的活性部分。