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DNA demethylation is the process of removal of a methyl group from nucleotides in DNA. DNA demethylation could be passive or active. The passive process takes place in the absence of methylation of newly synthesised DNA strands by DNMT1 during several replication rounds (for example, upon 5-Azacytidine treatment). Active DNA demethylation occurs via direct removal of a methyl group independently of DNA replication. ==Examples DNA Demethylation== All the cases of DNA demethylation can be divided as global (genome wide) or locus-specific (when just specific sequences are demethylated). The genome-wide DNA demethylation occurs: # In mammals: ## In the male pronucleus of zygote immediately after fertilization; ## In mouse primordial germ cells (PGCs) between E8.5-11.5 day old embryos; # Possibly in amphibia - during midblastula transition. Examples of specific DNA demethylation: # Genomic imprinting during plant reproduction; # Electroconvulsive stimulation-induced demethylation of neurotrophic factor genes in dentate gyrus neurons in the mouse brain. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「DNA demethylation」の詳細全文を読む スポンサード リンク
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