Use of the 5-bromodeoxyuridine-labelling technique for exploring mechanisms involved in the formation of chromosomal aberrations.

Synchronized G1 CHO cells with chromosomes of TB or TT constitution were irradiated with X-rays, short-wave UV and long-wave UV. The types and frequencies of chromosomal aberrations observed in the ensuing mitosis were studied. X-Rays induced predominantly chromosome types of aberration in chromosomes of TT constitution, whereas both chromosome- and chromatid-types of aberration were induced in cells with chromosomes of TB constitution. Short-wave UV induced only chromatid types of aberration in cells containing chromosomes of TT constitution, but both chromosome and chromatid types of aberration in cells with chromosomes of TB constitution. Long-wave UV induced chromosome and chromatid types of aberration in cells with chromosomes of TB constitution and no aberrations in cells containing chromosomes of TT constitution. Long-wave UV-irradiation of cells containing chromosomes of TB constitution increases the frequencies of SCEs. The relationship between chromosome constitution (TT or TB), the type of lesions induced by the 3 different agents employed, and the types of chromosomal aberration induced are discussed.