The proposal that N6-methyl-deoxyadenosine (m6dA) acts as an epigenetic mark in mammals remains controversial. Using isotopic labeling coupled to ultrasensitive mass spectrometry, we confirm the presence of low-level m6dA in mammalian DNA. However, the bulk of genomic m6dA originates from ribo-N6-methyladenosine, which is processed via the nucleotide-salvage pathway and misincorporated by DNA polymerases. Our results argue against m6dA acting as a heritable, epigenetic DNA mark in mammalian cells.

中文翻译：

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基因组N6-甲基-脱氧腺苷在哺乳动物细胞中的起源。

关于N6-甲基-脱氧腺苷（m6dA）充当哺乳动物表观遗传标记的提议仍存在争议。使用同位素标记与超灵敏质谱联用，我们确认哺乳动物DNA中存在低水平的m6dA。然而，大部分的基因组m6dA来源于核糖-N6-甲基腺苷，它是通过核苷酸挽救途径加工而成，并被DNA聚合酶误掺入。我们的研究结果反对m6dA在哺乳动物细胞中充当可遗传的表观遗传DNA标记。