[Fluorescent analysis of irradiation-induced changes in chromatin state]

A fluorescent technique with Hoechst-33258 and acridine orange staining was used to assess changes in chromatin state induced by radiation. Fluorochromes with different modes of binding to DNA were chosen. In T lymphocytes chronic irradiation caused a rearrangement of binding between nonhiston proteins and lipids accompanied by conformational changes in DNA, resulting in chromatin condensation. The decrease in fluorescence probably resulted from a reduction in the number of sites accessible for dye binding. After acute irradiation, the fluorescence intensity decreases predominantly due to double-strand breaks.