[The characteristics of the structural organization and spontaneous DNA damage in the cells of 2 lymphoma L5178Y lines differing in their radiosensitivity].

Nucleotide particles, resulting from mild lysis procedure, obtained from two strains of murine L5178Y lymphoma cells, differing in radiosensitivity (L-R and LY-S) showed differences in the sedimentation rate and in the halo rewinding in the presence of 40 micrograms/ml Ethidium bromide (EB). Microgel electrophoresis of DNA after an exhaustive lysis of cells (in the presence of sodium laurylsarcosine and proteinase for 20-24 h at room temperature) disclosed not only heterogeneity in DNA migration length among LY-R cells (LR) and LY-S cells (LS), but also differences between two strains with respect to this parameter. L-value for LY-S cells exceeds that for LY-R strain by 20 per cent, and the ratio LS/LR remains constant regardless of the voltage applied. Thus, the cell distribution pattern according to L-value is the intrinsic parameter for both LY-R and LY-S cells, and DNA of LY-S cells is suggested to bear more background strand breaks as compared with the radioresistant LY-R cells. LY-R cells irradiated with 10 Gy repair their DNA completely after 60-90 min of incubation at 37 degrees C but DNA migration pattern for irradiated and repaired LY-S cells is characterized by the predominance of DNA with a higher L-value than that for intact cells. Hence, we suggest that the higher radiosensitivity of LY-S cells might be compatible with a relatively high background DNA breakage in these cells.