Cytosine methylation and CpG, TpG (CpA) and TpA frequencies
Cytosine methylation and CpG, TpG (CpA) and TpA frequencies
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DOI：
10.1016/j.gene.2004.02.043
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发表时间：
2004-05-26
期刊：
影响因子：
3.5
通讯作者：
Bernardi, G
中科院分区：
文献类型：
--
作者：
Jabbari, K;Bernardi, G
对昆虫和哺乳动物的 DNA 以及果蝇、冈比亚按蚊、河豚鱼 (Takifugu rubripes)、斑马鱼 (Danio rerio) 和人类基因组的大 DNA 序列进行了二核苷酸频率分析。选择这些生物体是因为果蝇和按蚊 DNA 的甲基化水平极低，人类 DNA 的甲基化水平较高，而鱼类 DNA 的甲基化水平是人类的两倍。结果表明：（i）CpG缺乏和相应的TpG（CpA）过量与DNA甲基化水平没有相关性；事实上，具有显着不同 DNA 甲基化水平的基因组（例如果蝇和人类的基因组）表现出相似的 TpG (CpA) 水平。 (ii) 大 (50 kb) DNA 序列的 GC 水平与 TpA 或 CpG 短缺水平之间的相关性似乎不是由于 CpG 甲基化随后脱氨基造成的； (iii) CpG 二核苷酸在鱼类中比在哺乳动物中更常见；有趣的是，单孔类鸟类 Ornitorhinchus anatinus 显示出中等的 CpG 频率。讨论了这些结果的含义。 (C) 2004 Elsevier B.V. 保留所有权利。
An analysis of dinucleotide frequencies was carried out on DNAs from insects and mammals, as well as on large DNA sequences from the genomes of Drosophila melanogaster, Anopheles gambiae, puffer fish (Takifugu rubripes), zebra fish (Danio rerio) and human. These organisms were chosen because Drosophila and Anopheles DNAs have an extremely low level of methylation, human DNA a high level and fish DNA a two-fold higher level compared to human. The results indicate that: (i) CpG deficiency and the corresponding TpG (CpA) excess show no correlation with the level of DNA methylation; indeed, genomes endowed with strikingly different levels of DNA methylation (such as those of Drosophila and human) exhibited similar TpG (CpA) levels; (ii) the correlation between GC levels of large (50 kb) DNA sequences and TpA or CpG shortage levels do not appear to be due to CpG methylation followed by deamination; (iii) CpG dinucleotides are more frequent in fishes than in mammals; interestingly, the monotreme Ornitorhinchus anatinus shows an intermediate CpG frequency. The implications of these results are discussed. (C) 2004 Elsevier B.V. All rights reserved.