Detection of DNA lesions induced by chemical mutagens by the single cell gel electrophoresis (Comet) assay. 1. Relationship between the onset of DNA damage and the characteristics of mutagens.

We evaluated the relationship between the onset of DNA damage and the characteristics of 5 model chemical mutagens with the single-cell gel electrophoresis (SCG) assay using L5178Y mouse lymphoma cells. We treated the cells with each chemical for 3 h and sampled them 0, 21, and 45 h after treatment. DNA damage induced by UV mimetic mutagens MMS and MNU, and X-ray mimetic mutagen BLM was observed just after treatment, crosslinking agent MMC-induced DNA damage was detected 21 h after treatment, and 6-MP as an inhibitor of DNA synthesis did not induce DNA damage at any sampling time. These results suggest that the SCG assay detects DNA lesions just after treatment with UV and X-ray mimetic mutagens, but needs a waiting period after treatment with crosslinking agents.