Pristane induced effects on chromatin of rat lymphoid cells

The effects of pristane on the conformation of chromatin in cells isolated from the lymphoid tissues of pristane-treated Copenhagen rats were examined by flow cytometry, thermal denaturation, sensitivity to enzymatic digestion, and histone protein analyses. Decreases were observed in the fluorescent intensities of propidium iodide (PI) stained nuclei isolated from lymphoid cells of pristane-treated rats when compared with normal rat lymphoid nuclei. Studies to address the possible basis for the pristane-induced changes in the DNA staining characteristics of lymphocytes demonstrated that 1) there were no decreases in the amount of DNA present in the nuclei, 2) nuclei isolated from pristane treated rats were less sensitive to thermal denaturation, as well as DNase I enzymatic digestion, and 3) there were apparent increases in the expression of the H1 histone proteins. Collectively, these results suggest that pristane elicits a conformational change in the chromatin which may be mediated by altered expression of nuclear-associated histone proteins.