PHENOMENON AND MECHANISM OF SECONDARY DAMAGE DURING REPAIR OF DNA-DAMAGE IN IRRADIATED MAMMALIAN-CELLS

By means of comet assay, a study of kinetics curve of DNA damage repai r in irradiated SX-9 cells that came from mouse breast cancer proceede d. It was found that while the initial DNA damages had nearly been rep aired, DNA damages arose for the second time, then they were repaired again. As a result, a phenomenon of ''secondary damage'' was found dur ing the repair of DNA damages in irradiated SX-9 cells. Further resear ch illuminated that 3-aminobenzamide (3AB), which is an inhibitor of p oly (ADP-ribose) polymerase, could change the proceeding of ''secondar y damage''. For this reason it is possible that there exists some inne r relationship between the phenomenon of ''secondary damage'' and the function of poly(ADP-ribose) polymerase.