[Detection of DNA crosslinks with comet assay]

A simple and rapid method for the detection of DNA cross-links was explored. DNA cross-links was induced by formaldehyde (FA) in TK6 cells. Hydrogen peroxide was used as a standard DNA breakage agent. Two protocols on detecting DNA cross-links with comet assay were tested and compared. The results showed that with increasing FA, the length of DNA migration caused by H2O2 was decreased. When the level of FA was 1000 mumol/L, no any tailed cell could be observed, the migration of DNA was inhibited completely even H2O2 was used. The detection of DNA cross-link could be tested by both protocols. However, when the DNA cross-link agent (FA) was added to the cells before the treatment with DNA breakage agent (H2O2), the result of the scheme was much better than that in the opposite order. The former scheme was much easy to be manipulated, with no influence from DNA repair and had better dose-response relationship in the detection of DNA cross-links. The comet assay is indeed a sensitive, convenient and rapid method for the detection of DNA cross-link.