GENOTOXIC BIFUNCTIONAL ALDEHYDES PRODUCE SPECIFIC IMAGES IN THE COMETASSAY

Seven genotoxic aldehydes (acrolein, chloroacetaldehyde, crotonaldehyd e, formaldehyde, glutardialdehyde, glyoxal, and methylacrolein) have b een studied in vitro using the alkaline version of the comet assay (or single cell microgel electrophoresis assay) in freshly isolated rat h epatocytes. Chloroacetaldehyde, glyoxal and methylacrolein treatment r esulted in an elevated tail moment (TM), used as indicator for an DNA damaging activity and formation of comet like structures. In addition, this treatment also caused characteristic DNA spot images with small, highly condensed areas within the otherwise circular DNA spots. These were not seen in solvent and N-Methyl-N'-nitro-N-nitrosoguanidine (MN NG)-treated control cells. Treatment of hepatocytes with acrolein, cro tonaldehyde, formaldehyde and glutardialdehyde resulted in an TM which did not differ from those of control values although 86-95% of the ce lls showed characteristic changes of their DNA spot images. The conden sed areas are probably the consequence of the known DNA and protein cr osslinking activities of these bifunctional aldehydes. It is suggested that using the alkaline comet assay both TM (or overall comet length) as well as changes in the DNA spot image should be evaluated. (C) 199 8 Elsevier Science B.V. All rights reserved.