Optimisation of Arabidopsis thaliana DNA extraction for the analysis of 8-oxo-7,8-dihydro-2 '-deoxyguanosine formation after gamma irradiation

8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is a major oxidative DNA le sion. Plant DNA extraction protocols were improved in order to quantify 8-o xodGuo in the overall DNA of a cell suspension of Arabidopsis thaliana usin g the method of high performance liquid chromatography with electrochemical detection (HPLC-EC). Our results show that DNA can be artefactually oxidis ed during the extraction procedure. Metal chelating agents were efficient t o decrease the 8-oxodGuo background level to 3.3 +/- 0.1 8-oxodGuo/10(5)Gua and to improve experiment reproducibility. It was observed that DNA guanin e oxidation in plant cells by gamma-rays is very low in vivo (15 8-oxodGuo/ 10(9)Gua formation per Gy).