[Strength of nucleic acid-protein interactions and synthesis of nucleic acids and proteins in the cell]. / Prochnost' nukleinovo-belkovykh vzaimodeistvii i sintez nukleinovykh kislot i belka v kletke.

Nucleoprotein-celite chromatography of cultivated cells nuclei, where incorporation of 3H-thymidine, 3H-UTP and 14C-aminohydrolysate into the cells was studied, enabled to detect that lowering of DNA-protein interactions in intact cells occurred simultaneously with a decrease in the rate of spontaneous macromolecular synthesis. The natural growth-regulating drugs, which inhibited distinctly DNA synthesis, inhibited RNA synthesis only slightly and stimulated protein synthesis within the first hours of the cells cultivation, prevented a decrease in tightness of DNA-protein bonds at the beginning of cultivation and then contributed to the reaction thus correlating with inhibition of RNA and protein synthesis. Definite interrelationship was found between alterations in the chromatin structural state and the cells functional activity. The cells lost their functional activity after pronounced decrease in tightness of DNA-protein bonds.

[Mechanisms of the interaction of the leukemic cell with endogenous regulators of the proliferation of hematopoietic tissue]. / Mekhanizmy vzaimodeistviia leikoznoi kletki s éndogennymi reguliatorami proliferatsii krovetvornoi tkani.

A substance inhibiting DNA synthesis in mouse leukemic cells was isolated from the regenerating calf spleen. When added to a suspension of leukaemic cells, this substance is adsorbed on their surface. The following changes in cell features being noticed: 1) a minute decrease in electrophoretic cell motility, 2) a decrease in esterase activity of the cells, 3) an increase in microviscosity of membrane lipids, 4) an increase in the intracellular pH values. With a longer contact with this substance, changes in nuclear chromatin structure were noticed, with special reference to weakened bonds between DNA and proteins. The data obtained are of significance for revealing molecular mechanisms of hematopoietic mediator action on target cells.

[Structural properties of leukemic and normal lymphoid cells]. / Strukturnye svoistva leikoznykh i normal'nykh limfoidnykh kletok.

DNA synthesis intensity and spectral and fluorescent properties of leucemic, PHA-induced and intact normal mouse spleen cells and of nuclei isolated from these cells were investigated. The cell electrophoretic mobility and DNA-protein interaction in the nuclei were studied. Similarity in cell and nuclei fluorescence, fluorescence of the probe ANS conjugated with the cells, the electrophoretic mobility and tightness of DNA--protein interaction for leucemic and PHA--induced cells and also the similarity of the tightness of DNA--protein interaction for leucemic and normal intact cells were found inspite of the differences in DNA synthesis intensity and cell functional peculiarities.

[Effect of a substance isolated from the regenerating spleen on the chromatin structural organization and the leukosogenic activity of transplanted cells]. / Vliianie veshchestva, vydelennogo iz regeneriruiushchei selezenki, na strukturnuiu organizatsiiu khromatina i leikozogennuiu aktivnost' transplantirovannykh kletok.

When leukemic cells in vitro are treated with the substance isolated from the regenerating calf spleen, incorporation of 3H-thymidine into DNA is rapidly inhibited. The completeness of DNA synthesis restoration after washing off cells from the substance depends on the duration of the previous contact with the substance. It is the change in the structural organization of chromatin but not the very fact of inhibition of the ability of the cells to the DNA synthesis that is important for a decrease of transplantability of mice cells treated by the substance. The quicker the stability of the DNA/protein interaction in chromatin weakens due to the effect of the substance, the earlier the leukosogenic potential of the treated cells decreases.