Influence of partial deproteinization on the cytochemical properties of DNP of lymphocyte nuclei

Fixed lymphocytes from mouse lymphatic nodules were treated on histological preparations with sodium chloride solutions of varying molarity. The extracts were investigated electrophoretically and were found to contain all histone fractions after treatment with 1.5 M NaCl solution and only the histone F1 after treatment with 0.6 M solution. The cytochemical properties of the cells with histones removed were investigated. The experiments showed that histone removal resulted in a marked increase of nucleic capacity to bind AO, and in a significant decrease of DNP thermal stability of these cells in denaturation test. To establish the role played by histone F1 in the course of cell activation this histone was removed from lymphocytes in states of different activity. The experiments showed that after treatment with 0.6 M sodium chloride the difference in AO-binding of cells in states of different activity disappeared. The data obtained confirm the hypothesis about histone-DNA separation at early stages of chromatin activation and suggest that the early change in physico-chemical properties of chromatin are connected with the separation of lysine-rich histone F1.