Holliday R, Ho T
CSIRO Division of Biomolecular Engineering, Laboratory for Molecular Biology, North Ryde, NSW, Australia.
Somat Cell Mol Genet. 1991 Nov;17(6):537-42. doi: 10.1007/BF01233618.
Chinese hamster ovary (CHO) cells were subjected to electroporation in the presence of 5-methyl deoxycytidine-triphosphate. This treatment increases by 10 to 100-fold the frequency of cells lacking thymidine kinase, hypoxanthine-guanine phosphoribosyltransferase, or adenine phosphoribosyltransferase. The inactivation of the genes coding for these enzymes is thought to occur following the direct incorporation of the methylated nucleotide triphosphate into DNA. The enzyme-deficient clones were stable, but almost all were reactivated at high frequency by the demethylating agent 5-azacytidine, to produce derivatives with enzyme activity. The results indicate that there is a direct relationship between DNA methylation and gene silencing.
将中国仓鼠卵巢（CHO）细胞在5-甲基脱氧胞苷三磷酸存在的情况下进行电穿孔处理。这种处理使缺乏胸苷激酶、次黄嘌呤-鸟嘌呤磷酸核糖基转移酶或腺嘌呤磷酸核糖基转移酶的细胞频率增加了10到100倍。编码这些酶的基因失活被认为是在甲基化核苷酸三磷酸直接掺入DNA之后发生的。酶缺陷型克隆是稳定的，但几乎所有克隆都能被去甲基化剂5-氮杂胞苷高频重新激活，从而产生具有酶活性的衍生物。结果表明DNA甲基化与基因沉默之间存在直接关系。
