CYTOGENETIC RESULTS FROM A CHRONIC FEEDING STUDY OF MEIQX IN MICE

The primary food mutagens found in cooked meat are the heterocyclic ar omatic amines, including 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). High dose, acute exposures of MeIQx produce hepatic tumours in some mouse and rat strains. By assaying chromosome damage it may be possible to correlate aberrations with exposure to a mutagen. Whole c hromosome painting by fluorescence in situ hybridization allows the ra pid screening of metaphase chromosomes for rearrangements. This techni que was applied to female mice (C57BL/6) chronically fed 100-400 ppm M eIQx for up to 6 months. Two tissues, blood and bone marrow, were scre ened with multicolour whole chromosome painting probes (1, 2, 3 and 8) . The mice showed no outward signs of toxicity at any dose and very fe w chromosome aberrations were observed. A slight but significant incre ase in sister chromatid exchanges (SCE) was seen at 400 ppm in blood a t 6 months. When MeIQx was removed from the diet for 1 month there was an apparent decline in SCEs only for animals previously given the 400 ppm diet. Published by Elsevier Science Ltd