Abanobi SE, Columbano A, Mulivor RA, Rajalakshmi S, Sarma DS. In vivo replication of hepatic deoxyribonucleic acid of rats treated with dimethylnitrosamine: presence of dimethylnitrosamine-induced O6-methylguanine, N7-methylguanine, and N3-methyladenine in the replicated hybrid deoxyribonucleic acid.
Biochemistry 1980;
19:1382-7. [PMID:
7387997 DOI:
10.1021/bi00548a018]
[Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Experiments were designed to determine whether some chemical lesions such as O6-methylguanine, N7-methylguanine, and N3-methyladenine induced in rat liver DNA by the hepatocarcinogen dimethylnitrosamine permit replication in vivo. For this purpose, [14C]dimethylnitrosamine was administered to methylate the parental strand of liver DNA. Four hours later, a time period when the carcinogen cannot be detected in either the liver or the blood, rats were subjected to partial hepatectomy in order to induce DNA replication. During the S phase, 5-bromo-2-deoxyuridine was administered to render the newly made strands heavy. The rebanded, hybrid, hepatic DNA of density 1.714 g/cm3 and greater was pooled from the neutral cesium chloride gradient, dialyzed, and lyophilized. The hybrid DNA was then treated with S1 nuclease to digest any single-stranded regions. The results obtained indicated the presence of O6-methylguanine, N7-methylguanine, and N3-methyladenine in S1 nuclease resistant, hybrid DNA. The results are interpreted to indicate that these chemical lesions permitted in vivo DNA replication.
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