DETECTION OF CHROMOSOME-2 AND CHROMOSOME-7 WITHIN X-RAY-INDUCED OR COLCHICINE-INDUCED MICRONUCLEI BY FLUORESCENCE IN-SITU HYBRIDIZATION

The occurrence of chromosome 2 and chromosome 7 within micronuclei of binucleated lymphocytes induced by X-rays or colchicine was scored usi ng the whole chromosome painting technique. The observed frequency of involvement in micronucleus formation was compared with the yield that would be expected theoretically, when the random participation of eac h chromosome is assumed, No difference was observed between the expect ed and observed inclusion of chromosome 2 or chromosome 7 into micronu clei after X-ray exposure (2.5 Gy). This was also the case for chromos ome 2, but not for chromosome 7 after colchicine treatment (0.04/0.06 mu g/ml); chromosome 7 was detected approximately 1.5 times more frequ ently in micronucleus formation than would be expected from the assump tion of a random distribution.