DETECTION OF CHEMICALLY-INDUCED DNA LESIONS IN MULTIPLE-MOUSE ORGANS (LIVER, LUNG, SPLEEN, KIDNEY, AND BONE-MARROW) USING THE ALKALINE SINGLE-CELL GEL-ELECTROPHORESIS (COMET) ASSAY

The effect of 2 model chemical mutagens on DNA was evaluated with the alkaline single cell gel electrophoresis (SCG) (Comet) assay in 5 mous e organs - liver, lung, kidney, spleen and bone marrow. Mice were sacr ificed 3 and 24 h after the administration of the direct mutagen ethyl nitrosourea (ENU) or the liver-targeting promutagen p-dimethylaminoaz obenzene (DAB). Each organ was minced, suspended at a concentration of 1 g/ml in chilled homogenizing buffer (pH 7.5) containing 0.075 M NaC l and 0.024 M Na(2)EDTA, homogenized gently using a Potter-type homoge nizer at 500-800 rpm set in ice, and then centrifuged nuclei were used for the alkaline SCG assay. ENU induced DNA damage in cells all of th e organs studied, DAB, on the other hand, produced a positive response in the liver only. We suggest that it may be possible to use the alka line SCG assay using a homogenization technique to detect the genotoxi city of chemicals in vivo in their target organs.