Correlation of chromosomal aberrations and sister chromatid exchanges in individual CHO cells pre-labelled with BrdU and treated with DNaseI or X-rays

Purpose : To analyse the correlation between chromosomal aberrations and sister-chromatid exchanges (SCE) in cells treated in G1 phase with X-rays or DNaseI. Materials and methods : Chinese hamster ovary (CHO) cells were labelled with 5'-bromodeoxyuridine (BrdU) for one round of replication and irradiated in G1 phase with 1.2, 2.4, 3.6 and 4.8 Gy X-rays or treated by electroporation with 1000, 2000, 3000 and 4000 units DNaseI per 800 μ l electroporation buffer. Using a computer-aided metaphase relocation system first post-treatment mitoses were analysed for SCE and chromosomal aberrations allowing a precise investigation of correlation between both phenomena. Results : A better correlation between aberrations and SCE was observed for DNaseI than for X-rays. X-rays induced more SCE than expected on the basis of aberrations, whereas the frequencies of SCE induced by DNaseI can mainly be accounted for by chromosomal aberrations. Discussion : The results obtained with X-rays support an earlier observation tha...