Estimation of the Mutagenic Potential of 8-Oxog in Nuclear Extracts of Mouse Cells Using the "Framed Mirror" Method

We propose an improved earlier described "mirror" method for detecting in cell nuclear extracts mutations that arise in DNA during its replication due to the misincorporation of deoxyadenosine-5'-monophosphate (dAMP) opposite 7,8-dihydro-8-oxoguanine (8-oxoG). This method is based on the synthesis of a complementary chain ("mirror") by nuclear extracts of different mice organs on a template containing 8-oxoG and dideoxycytidine residue (ddC) at the 3'‑end. The "mirror" was amplified by PCR using primers part of which was non-complementary to the template. It allowed obtaining the "framed mirror" products. The misincorporation of dAMP in "framed mirror" products forms an EcoRI restriction site. The restriction analysis of double-stranded "framed mirror" products allows a quantification of the mutation frequency in nuclear extracts. The data obtained show that the mutagenic potential of 8-oxoG markedly varied in different organs of adult mice and embryos.