[Effect of autoinducers of anabiosis for some microorganisms on rat liver mitochondria respiration]. / Deistvie autoinduktorov anabioza nekotorykh mikroorganizmov na dykhanie mitokhondrii pecheni krysy.

2-(4-Hydroxyphenyl)ethane-1-ol (tyrosol) and 5-n-alkyl(C19,C21)resorcinols produced by some microorganisms as anabiosis autoregulators (factors d1) inhibit the electron transport and uncouple oxidative phosphorylation in the respiratory chain of rat liver mitochondria: a 50% decrease of the respiratory control is caused by 0.32-0.36 mumol of tyrosol or by 0.21-0.26 mumol of alkylresorcinols per mg of protein. Alkylresorcinols reduce the NADH-dehydrogenase and succinate dehydrogenase activities in mitochondria, whereas tyrosol acts predominantly on the NADH-dehydrogenase activity.

[Tyrosol--the autoregulatory d1 factor of the yeast Saccharomyces cerevisiae]. / Tirozol--autoreguliatornyi faktor d1 drozhzhei Saccharomyces cerevisiae.

The autoregulatory d1 factor of the yeast, Saccharomyces cerevisiae, that induces the transition of vegetative cells into refractory resting forms, has been isolated from the cell-free culture medium as an individual crystalline compound. It has been shown to be 2-(4-hydroxyphenyl)ethane-1-ol which is also known as tyrosol. When added to the producer culture at 5-15 microM concentration, tyrosol stimulated the endogenous respiration of cells, but inhibited at 20-80 microM concentration. At 200-800 microM concentration, it induced the occurrence of resting forms. The action of tyrosol was not specific, for it also inhibited the cell respiration of the bacteria, Escherichia coli and Bacillus cereus, at 64-86 microM concentration.

Membrane-structuring properties of bacterial long-chain alkylresorcinols.

To investigate the mechanism by which 5-n-alkyl(C19-C25)-resorcinols synthesized by certain bacteria of the Azotobacter genus affect the lipid bilayers of cellular membranes, planar bimolecular membranes were formed from these alkyl-resorcinols and from mixtures of those and typical bacterial phospholipids such as phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The electrical properties and, in some instances, the stability of the prepared membranes have been studied. The alkylresorcinols have been found to associate with phospholipids to form oligomeric and polymeric complexes, thereby giving rise to modifications in the bilayer structure and properties. It has been shown that the same compounds suppress the mitochondrial respiration in the presence of NAD-dependent substrates, but they activate it if succinate is used as substrate. This fact is explained in terms of the interaction between the alkylresorcinols and membrane phospholipids.

[The effect of isomeric alkyl (C19--C25) methoxybenzoquinones on mitochondrial respiration]. / Vliianie izomernykh alkil(C19--C25)netoksibenzokhinonov na dykhanie mitokhondrii.

The influence of 2-methoxy-6-alkyl(C19-C25)benzoquinones-1,4 and 4-methoxy-6-alkyl(C19-C25)benzoquinones-1,2 on the respiration of isolated rat liver mitochondria has been studied. As a concentration of each of the quinones increased gradually from zero, the rate of the respiration using NAD-dependent substrates firstly increased but then decreased, 1,2-quinones being the more potent inhibitors. Concurrently, the respiratory control of mitochondria was lowered, indicating uncoupling effect of these quinones. With succinate the latter exhibited moderately accelerating effect. Uncoupled by 2,4-dinitrophenol, the respiration was stimulated by the both preparations in the presence of succinate but was suppressed when NAD-dependent substrates were used. The observed inhibitory effects have been assumed to be caused by a competition between the quinones and endogenous co-enzyme Q for the active site of NADH-dehydrogenase complex of the respiratory chain.

[Effect of berberine, glaucine, stephaglabrine and sanguiritrine on neuromuscular transmission]. / Deistvie berberina, glautina, stefaglabrina i sangviritrina na nervno-myshechnuiu peredachu.

Natural alkaloid drugs, glaucine, stephaglabrine and sanguiritrine, are shown to affect the synaptic transmission in a fairly complicated manner and seem to involve several different mechanisms of action. These substances as well as berberine reduce amplitude of the spontaneous miniature end plate potentials in a frog neuromuscular junction. At low concentrations all the mentioned alkaloids diminish frequency of miniature potentials, but increase it when their concentration exceeds a certain value. Sanguiritrine is the most active in this respect (nearly a 100-fold increase), that is probably associated with its uncoupling effect on the mitochondrial oxidative phosphorylation. Sanguiritrine and stephaglabrine both cause repeated muscle contractions, that is in line with their anti-cholinesterase properties. Glaucine provokes only muscle contracture if present at relatively high concentration.

[5-Alkyl(C19-C25) resorcinols as regulators of succinate and NAD-dependent substrate oxidation by mitochondria]. / 5-Alkil(C19-C25)rezortsiny--regulatory okisleniia mitokhondriiami suktsinata i NAD-zavisimykh substratov.

The effect of 5-n-alkyl(C19-C25) resorcinols isolated from Azotobacter chroococcum on the oxidation of succinate and NAD-dependent substrates (glutamate, alpha-ketoglutarate, malate, pyruvate) by rat liver mitochondria was studied, using the polarographic technique. With succinate, the above resorcinol lipids activated to some extent the 2,4-dinitrophenol-decoupled mitochondrial respiration, but markedly suppressed it (up to 95%) in the presence of NAD-dependent substrates. The activating and inhibiting effects correlated with the resorcinol lipid/mitochondrial proteins ratio and were observed, when the lipid concentration in the incubation mixture ranged from 2.4.10(-4) to 6.0.10(-4) M. The most striking inhibiting effect was observed with alpha-ketoglutarate as substrate. The results obtained suggest that 5-n-alkyl(C19-C25) resorcinols should be regarded as rotenone type regulators of cell respiration.

[Interaction of perfluoro-organic compounds with flat lipid bilayers]. / Vzaimodeistvie perftororganicheskikh soedineniii s ploskim lipidnym bisloem.

It has been found that contact interaction between the drops of perfluoro-organic compounds (PFOC) and bilayer lipid membranes (BLM) results in the fusion of PFOC and BLM drops. In the process PFOC is incorporated into the lipid bi layer of BLM, which decreases the BLM stability.

[Inclusion of erythrocyte membranes into planar lipid bilayers]. / Vkliuchenie membrany éritrotsitov v ploskie bisloinye lipidnye membrany.

Planar lipid bilayer membranes (PM) were modified by membrane vesicles prepared from rabbit erythrocytes. Vesicles contained amphotericin B and tetraethylammonium. Voltage-current relationships of modified PM were investigated. Semi-fusion, the inclusion of sealed vesicles into PM with formation of contact bilayer consisting of one lipid monolayer of the erythrocyte membrane and another monolayer of PM, was shown to appear some minutes after the contact of vesicles with PM. Some tens of minutes later fusion of the erythrocyte membranes with PM was observed. Fusion occurred either by opening out of vesicles or by incorporation of sealed vesicles into PM. The temperature rise increased the fusion probability. Sealed vesicles were incorporated in PM asymmetrically: the contact area was always smaller than the noncontact vesicle surface.

[Two stages of contact interaction of liposomes with bimolecular lipid membranes]. / Dve stadii kontaktnogo vzaimodeistviia liposom i biomolekuliarnykh lipidnykh membran.

Interaction of liposomes with BLM is confirmed to consist of two stages. The first stage is a semi-fusion of liposomes with BLM. On this stage the bilayer in a contact area is formed of one liposome monolayer and another one of BLM. The second stage is inclusion of liposome bilayers into BLM; it occurs some tens of minutes after the first one. It occurs either by fusion or incorporation. The fusion to incorporation ratio increases with temperature. Liposomes are incorporated in BLM asymmetrically: the contact area of the liposome bilayer is always smaller than the free one.

[Reaction between liposomes and biomolecular membranes]. / Vzaimodeistvie liposom s bimolekuliarnymi membranami.

Small liposomes did not change the resistance of bimolecular lipid membranes (BLM) in monovalent ion solution (less than or equal to 0.5 M). The interaction between liposomes containing cholesterol and BLM free from cholesterol in the solution of polyene antibiotic nystatine induced anion selectivity and smooth growth of BLM conductance by 4--5 orders. The addition of the liposomes containing cholesterol and nystatine induced a step-like fall of BLM resistance by 2--3 orders. Both cation-selective and anion-selective steps was observed. The effects observed point to the fusion and incorporation of liposome into BLM.

[Electrophoretic mobility of bimolecular lipid membranes]. / Elektroforeticheskaia podvizhnost' bimolekuliarnykh lipidnykh membran.

The floating membrane vesicle is fixed by the counter solution flow in different points along the radius of a cylinder electrophoretic chamber, which permits to measure the vesicle electrophoretic mobility (EM). Close state condition of the chamber is provided for by the capillary system successively connected with the chamber. Relationship between EM of bimolecular lipid membranes (BLM) and pH and ionic concentration of aqueous solution qualitatively coincides with similar relationship for liposomes. The EM value of BLM essentially decreases in solution containing polyene antibiotics nystatine and levorin when derivative of cholesterol having 3betaOH-groups is present in the membrane.

Cctionic selectivity of bimolecular membranes in the presence of nystatin and amphotericin B. / Issledovanie kationnoi izbiratel'nosti bimolekuliarnykh membran v prisutstvii nistatina i amfoteritsina b

Ergosterin or 7-dehydrocholesterin-containing artificial membranes are selectively permeable for cations of alkaline metals in aqueous solutions of nistatin and amphotericine B. Membrane permeability changes spontaneously within several tens of minutes from the cation to the anion one. A decrease of temperature, an increase of medium pH or introduction of dimethylsulphoxide into aqueous solution inhibit, while the addition of calcium accelerate this transition.

A study of the mechanism of quantal transmitter release at a chemical synapse.

1. The nerve-muscle preparation of the cutaneous pectoris of the frog has been used to study quantal transmitter release.2. When the osmotic pressure of the external solution is raised 1.5-2 fold, the frequency of miniature end-plate potentials (m.e.p.p.s) rises by 1.5-2 orders of magnitude. This effect is independent of the presence of Ca(2+) ions and of the nature of the substances by which the osmotic pressure has been increased.3. In Ca(2+) free hypertonic solution the nerve impulse still invades the nerve terminals but does not alter the frequency of the m.e.p.p.s.4. The arrival of the impulse in the terminals causes an immediate increase in the rate of quantal release, provided divalent cations are present whose passage through the axon membrane is facilitated by excitation (Ca(2+), Sr(2+), Ba(2+)).5. Divalent cations which penetrate only slightly (Mg(2+), Be(2+)) lower the frequency of m.e.p.p.s and suppress the end-plate potential (e.p.p.) evoked by an impulse, in the presence of Ca(2+) ions. Be(2+) is a more effective inhibitor than Mg(2+).6. In Ca(2+) free solutions, adding Mg(2+) causes an increase in the frequency of m.e.p.p.s evoked by depolarization of the nerve endings or by treatment with ethanol.7. The trivalent cation La(3+) is more effective than divalent cations are in increasing the frequency of m.e.p.p.s. The tetravalent cation Th(4+) also raises the m.e.p.p. frequency.8. The observations summarized in paragraphs 2-7 indicate that the frequency of m.e.p.p.s at a constant temperature depends only on the concentration of uni-, di- and trivalent cations inside the nerve ending. It is suggested that the internal cation concentration influences the adhesion between synaptic vesicles and the membrane of the nerve ending.9. For a model experiment, artificial phospholipid membranes have been used to study the effect of uni-, di-, tri- and tetravalent cations on the adhesion process. At pH 7-7.4, the time required for adhesion to take place decreases with increasing cation concentration in the bath. Ca(2+) ions are 100-1000 times more effective than K(+) ions; La(3+) and Th(4+) ions are still more effective. The ;adhesion time' decreases when the pH is lowered; it increases greatly with lowering of temperature.10. The hypothesis is put forward that the mutual adhesion of artificial vesicles made of phospholipid membranes, and the adhesion between synaptic vesicles and the membrane of the nerve ending arise by a common mechanism. In both cases, the important factor is the influence of cations on the electric double layer at the membrane surface.