RADIATION-INDUCED DAMAGE IN 2 HUMAN GLIOMA CELL-LINES AS MEASURED BY THE NUCLEOID ASSAY

We measured radiation-induced damage and repair in MO59J and MO59K hum an glioma cell lines using the nucleoid halo assay. Although these two cell lines have different radiosensitivities when assayed for colony forming efficiency, our results indicated that there was no significan t difference between the two in terms of the unwinding and rewinding o f DNA supercoils, radiation-induced changes in nucleoid halo size or t he kinetics of nucleoid halo lysis. The only differences noted were in the kinetics of recovery of radiation-induced changes in nucleoid hal o size, with the more sensitive cell line (MO59J) showing a slightly f aster recovery than the more resistant cell line (MO59K). However, thi s difference was not statistically different Our data indicate that th e different cellular radiosensitivities of MO59J and MO59K cells are p robably not due to any differences in their supercoiled DNA structure as measured by the nucleoid halo assay.