Fong L Y, Lin H J, Lee C L
Int J Cancer. 1979 May 15;23(5):679-82. doi: 10.1002/ijc.2910230514.
The sites of labelling of DNA with [14C]methyl groups from methylbenzylnitrosamine and dimethylnitrosamine were studied in rat oesophageal epithelium and liver. All four combinations of tissue and carcinogen were studied. Tissues were labelled in vitro and the DNA contained therein purified and hydrolysed (pH 1, 37 degrees C) to free purines and apurinic acid. Quantitative analysis was performed with the aid of thin-layer chromatography. The apurinic acid and 7-methylguanine fractions were found to be extensively labelled. Smaller amounts of radioactivity were found in O6-methylguanine and some of the methylated adenines. The same carcinogen produced different patterns of labelling is oesophageal and liver DNA. The proportion of O6-methylguanine to 7-methylguanine was higher when the methylating agent was a carcinogen specific for the organ.
研究了甲基苄基亚硝胺和二甲基亚硝胺中[¹⁴C]甲基对大鼠食管上皮和肝脏DNA的标记位点。对组织和致癌物的所有四种组合进行了研究。组织在体外进行标记，其中所含的DNA经纯化并水解（pH 1，37℃）以释放出游离嘌呤和脱嘌呤酸。借助薄层色谱法进行定量分析。发现脱嘌呤酸和7-甲基鸟嘌呤部分被大量标记。在O⁶-甲基鸟嘌呤和一些甲基化腺嘌呤中发现的放射性较少。相同的致癌物在食管和肝脏DNA中产生不同的标记模式。当甲基化剂是器官特异性致癌物时，O⁶-甲基鸟嘌呤与7-甲基鸟嘌呤的比例更高。
