Bleomycin - Induced DNA damage and DNA repair in chicken embryo cells as compared to X-irradiation

Following iii vitro- and in ovo-exposure of chicken embryo cells, the level of bleomycin (BM) - induced damage was evaluated by using DNA synthesis, n ucleoid sedimentation (SED), and viscometry of alkaline cell lysates (VISC) . This damage was compared to X-irradiation, using 5.9-378 nM BM in vitro, 1.5-116 mu g BM/egg in ovo, and 2-32 Gy, respectively in vitro as well as i n ovo. With respect to BMI the most notable result is the increase in DNA s ynthesis and VISC at the lowest concentrations of the drug. A decrease in b oth parameters was observed at high BM concentrations and following exposur e to X-rays, concomitantly with an increase in SED. Regarding the radiomime tic drug BM and X-rays, different modes of DNA damage and DNA repair are su ggested by previous investigations and the present results. Therefore, furt her evidence is presented, that the chicken embryo can act as a simple, rap id and inexpensive test system to characterize the biological effects of ma ny nucleo- and/or cytotoxic agents.