The role of Ca ions in restoration of the structure of interphase and mitotic chromosomes in PK living cells after hypotonic stress.

The dynamics of mitotic chromosome and interphase chromatin recondensation in living PK cells during their adaptation to hypotonic medium was studied. The recondensation process was found to be slowed down by the modification of plasma membrane with low concentrations of glutaraldehyde, while osmotic reactions of glutaraldehyde-treated cells remain unchanged. The effect of glutaraldehyde can be rapidly reversed by the addition of Ca(2+)-ionophore A23187.

Glucose strongly stimulates rate of the rRNA synthesis in Ehrlich ascites carcinoma cells.

A change in glucose concentration in an Ehrlich ascites carcinoma cell suspension from 0.1 mM to 20 mM causes a more than 50-fold stimulation of the rate of ribosomal RNA synthesis. Such an effect occurs without any dramatic effect on the rate of protein synthesis in cells.

[Dependence of the nature of the action of metabolic inhibitors on ribosomal RNA synthesis in Ehrlich ascites carcinoma cells on cell integrity].

Ribosomal RNA (rRNA) synthesis in the intact Ehrlich ascite carcinoma cells is selectively inhibited by papaverin (ED50 = 0.01 mM), 2,4-dinitrophenol (DPN; ED50 = 5 microM), and actinomycin D (ED50 = 0.1 microgram/ml).

[Inhibitor interaction in the suppression of ribosomal RNA synthesis in Ehrlich ascites carcinoma cells].

Kinetic analysis of inhibitory action of papaverine, 2,4-dinitrophenol (DNP) and actinomycin D on RNA synthesis in the intact Ehrlich ascites carcinoma cells has shown that the action of these agents is mediated by their effect on the same step of rRNA synthesis.

[Effect of 2,4-dinitrophenol on the synthesis of ribosomal RNA in the cells of Ehrlich ascitic carcinoma under anaerobic conditions].

It is shown that 2,4-DNP (20 mkM to 1 mM) selectively inhibited RNA synthesis in Ehrlich ascite carcinoma cells both in aerobic and in anaerobic conditions in equal extent. It is supposed that the inhibitory action of DNP is not associated with its influence on oxidative phosphorylation and intracellular ATP concentration, but may be accounted for cell reaction to non-specific actions.

[Effect of cycloheximide, 2,4-dinitrophenol and papaverine on ribosomal RNA synthesis in Ehrlich ascitic carcinoma cells].

The influence of 2,4-dinitrophenol (DNP), papaverine and cycloheximide on RNA synthesis in Ehrlich ascites tumour cells has been investigated. All above mentioned agents inhibit selectively synthesis of high-molecular rRNA precursor, when the cell population density is 3.10(7)--5.

[Effect of a number of metabolic inhibitors and other biologically active substances on the development of sea urchin embryos].

Benzo(a)pyrene, hydrocortisone, corticosterone, ethidium bromide, actinomycin D and papaverin arrested the development of sea urchin embryos at the stage of early gastrula when the synthesis of rRNA increases. The fertilization membrane did not prevent the penetration of hydrocortisone and benzo(a)pyrene in the embryo cells. These drugs did not affect RNA synthesis at the early stages of development and markedly suppressed it at the early gastrula stage.