[On the role of gene of SER-4 serotonin receptor in thermotolerance of Caenorhabditis elegans behavior].

Serotonin reduces the behavior tolerance of Caenorhabditis elegans of the N2 wild-type strain (swimming induced by the mechanical stimulus) to a temperature of 36 degrees C. The sensitivity to the serotonin influence on the behavior thermotolerance remains intact in strains with null mutations of mod-1 (ok103) and ser-1 (ok345) serotonin receptor genes, and is almost completely lost in the ser-4 (ok512) strain with null mutation in the gene of the SER-4 serotonin receptor, which is a homologue of 5-HT1 mammalian serotonin receptor. In addition, nematodes of the ser-4 (ok512) strain have high behavior thermotolerance in the absence of the exogenous serotonin compared to the N2 strain. These data indicate the involvement of the ser-4 gene in the serotonin regulation of the tolerance of C. elegance nervous system functions to hyperthermia.

Ethanol sensitizes the nervous system of Caenorhabditis elegans nematode to heat stress.

Ethanol sensitizes the nervous system of C. elegans to heat stress, which manifested in exacerbation of locomotion disturbances induced by exposure to constant temperature 36°C. Adaptation of C. elegans to high temperature by heat shock (1 h at 32°C and 1 h at 18°C) or two-hour exposure at 30°C resulted considerably reduced sensitivity of the nervous system to the negative effects of ethanol under conditions of heat stress.

[Characterization of new Caenorhabditis elegans lines with a high thermotolerance].

The lines of Caenorhabditis elegans displaying low (LT) and high (HT1, HT2, and HT3) thermotolerance were obtained from the wild line N2 by artificial selection for thermostability of locomotion and by natural selection in laboratory for thermotolerance of fertility under tolerable environmental temperature elevation. All these lines are new genetic variants that emerged during the experiment. The worms of lines HT2 and HT3 displayed an elevated upper temperature limit for reproduction (from 26 to 27.5 degrees C), thermostability of locomotion at 36 degrees C, and survival at 37 degrees C as compared with the line N2. The results have demonstrated that adaptation of C. elegans to high temperatures is an appropriate laboratory model for studying the mechanisms involved in the evolution of thermotolerance of poikilothermic Metazoa.

[A calcium channel in the rat liver inner mitochondrial membrane. Effective diameter and selectivity under various conditions]. / Kal'tsievyi kanal vnutrennei membrany mitokhondrii pecheni krysy. Effektivny diameter i selektivnost' v razlichnykh usloviiakh.

The pore with an effective diameter of 6.0 A is a Ca(2+)-channel of the inner mitochondrial membrane. Transport of nonelectrolytes through the pore is inhibited by ruthenium red, a specific Ca2+ transport inhibitor, and by polyanions which bind to the positively charged regions in the pore localized on the outer side of the inner mitochondrial membrane. The selectivity of Ca2+ ion transport into intact mitochondria is due to the binding of Ca2+ ions by the glycoprotein at the mouth of the pore as well as to electrostatic interactions of monovalent cations (electrostatic repulsion) and Cl- ions (strong binding) with the positively charged region of the ion-selective filter of the pore. Under normal conditions SCN- and NO3- ions are transferred through the pore at a high rate. Removal of Mg2+ ions and the rise in pH diminish the electrostatic repulsion of the monovalent cations and Cl- ions from the positively charged region of the pore. Depending on conditions, the pore can function as a monovalent ion transport system or as a mechanism of Cl- ion transfer through the inner mitochondrial membrane.

[Oxidative phosphorylation uncoupling in hyperthyroidism as a result of activating cyclosporin-sensitive pores in the inner mitochondrial membrane by water soluble modulators from rat liver cytoplasm]. / Razobshchenie okislitel'nogo fosforilirovaniia pri gipertireoze kak sledstvie aktivatsii tsiklosporinchuvstvitel'noi pory vo vnutrennei membrane mitokhondrii vodorastvorimymi moduliatorami iz tsitoplazmy pecheni krysy.

Small concentrations of low molecular weight modulators of the functional state of rat liver cytoplasm mitochondria, which uncouple oxidative phosphorylation, induce phosphate-dependent transport of potassium and hydrogen ions. In contrast, high concentrations of these compounds induce nonspecific transport of monovalent cations and sucrose (K+ > H+ > Na+ > or = Li+ > sucrose). The effect of cytoplasmic modulators on oxidative phosphorylation and permeability of the inner mitochondrial membrane in inhibited by cyclosporin A and controlled by physiological concentrations of Ca2+. It is assumed that ion transport across the inner mitochondrial membrane in the presence of cytoplasmic modulators is implemented by the same cyclosporin-sensitive transport system which in damaged mitochondria functions as a nonspecific pore.

[Effective diameter of pores in rat liver mitochondria inner membrane and selectivity of transport of monovalent cations with a submicromolar concentration of Ca2+ ions or A23187 and EDTA]. / Effektivnyi diameter pory vo vnutrennei membrane mitokhondrii pecheni krysy i selektivnost' transporta odnovalentnykh kationov pri deistvii submikromoliarnykh kontsentratsii ionov Ca2+ ili A23187 i EDTA.

Studies of swelling of rat liver mitochondria in isoosmotic solutions of nonelectrolytes in the presence of respiration inhibitors revealed that submicromolar concentrations of Ca2+ increase the diameter of pores in the inner mitochondrial membrane--from 5.5-6.0 A (10(-8) M Ca2+) up to 7.5 A (3 x 10(-7) M Ca2+) and 8.0-8.5 A (6 x 10(-7) M Ca2+); these increases are prevented by cyclosporin A. The inner mitochondrial membrane with an effective pore diameter of 7.5 A is readily permeable for potassium but not for sodium ions, although with an increase in the effective pore diameter up to 8.0-8.5 A the selectivity of the K(+)-Na+ channel decreases. A conclusion is drawn that in the presence of submicromolar concentrations of Ca2+ the conductivity of the cyclosporin-sensitive pore for monovalent cations increases in the following order: K > Na > Li.

[Regulation of thyroid hormones of the interaction of mitochondria with low-molecular weight cytoplasmic mediators, induced by phosphate- dependent transport of K+ and H+ ions through the mitochondrial inner membrane]. / Reguliatsiia tireoidnymi gormonami vzaimodeistviia mitokhondrii s nizkomolekuliarnymi tsitoplazmaticheskimi mediatorami, indutsiruiushchimi fosfatzavisimyi transport ionov K+ i H+ cherez membranu mitokhondrii.

In vivo thyroid hormones control the binding to mitochondria of low molecular weight water-soluble cytoplasmic mediators that are capable to induce oxidative phosphorylation uncoupling, by increasing the sensitivity of mitochondria to the effects of these mediators. In hyperthyroid rat liver mitochondria cytoplasmic mediators stimulate the phosphate-dependent transport of K+ and H+ in a greater degree than in liver mitochondria of control rats. The increase in the oxidative phosphorylation uncoupling by cytoplasmic mediators is one of mechanisms of thermogenesis stimulation by thyroid hormones.

[Isolation of low molecular weight cytoplasmic regulators from the rat liver inducing the electrophoretic transport of K+ ions and phosphate across the inner mitochondrial membrane]. / Vydelenie nizkomolekuliarnykh tsitoplazmaticheskikh reguliatorov iz pecheni krysy, indutsiruiushchikh lektroforeticheskii transport ionov K+ i fosfata cherez vnutrenniuiu membranu mitokhondrii.

A water-soluble thermostable factor from rat liver cytoplasm whose activity decreases during starvation, causes the uncoupling of oxidative phosphorylation and stimulates pyruvate oxidation in rat liver mitochondria. The activity of this factor is insensitive to pronase treatment. Gel filtration and ion-exchange chromatography resulted in three low molecular weight water-soluble fractions which bear a negative charge at alkaline values of pH and induce electrophoretic transport of K+ and phosphate across the inner mitochondrial membrane. The effect of this factor on K+ transport is manifested at pH less than or equal to 7.0, that on phosphate transport-at pH 6.5-7.6.

[Regulation of oxidative phosphorylation, K+ ions transport and the volume of mitochondrial matrix by cytoplasmic glycopeptide and Ca2+ ions]. / Reguliatsiia okislitel'nogo fosforilirovaniia, transporta ionov K+ i ob''ema matriksa mitokhondrii tsitoplazmaticheskim glikopeptidom i ionami Ca2+.

A thermostable low molecular weight glycopeptide containing syalic acids, which uncouples mitochondrial oxidative phosphorylation, has been detected, isolated and purified from rat liver cytoplasm. In the presence of the glycopeptide, oxidative phosphorylation in rat liver mitochondria is uncoupled by low physiological concentrations of Ca2+, which otherwise do not have any appreciable effect on the mitochondria. Oxidative phosphorylation uncoupling by the glycopeptide is accompanied by an increase of the mitochondrial volume. This process has a limited amplitude and is regulated by changes in Ca2+ concentration in the extramitochondrial space. The glycopeptide has been shown to induce K+ transport across the inner mitochondrial membrane, this effect is enhanced by Ca2+.

[Effect of pregnancy and progesterone on the activity of an insulin-dependent cytoplasmic regulator in the liver, heart and diaphragm of rats]. / Vliianie beremennosti i progesterona na aktivnost' insulinzavisimogo tsitoplazmaticheskogo reguliatora v pecheni, serdtse i diafragme krys.

The activity of the insulin-dependent regulator (IDR) in the thermostable fraction of the cytoplasm isolated from the liver, heart and diaphragm of rats as well as the glycogen level in the liver were estimated. The IDR activity in the insulin target organs and glycogen concentration in the liver were raised in the pregnant well-fed rats; a tendency to their decrease was observed after 24 h starvation. The range of changes between satiation and starvation was much more pronounced in the pregnant rats than in the controls. The IDR activity was also higher in well-fed rats receiving progesterone for 5 days and did not change after a single injection of progesterone. It was concluded that a raised level of progesterone in the blood was one of the reasons for an increase in the IDR activity in pregnant rats. An increase in the IDR activity in the insulin target organs under conditions of insulin resistance induced by pregnancy or progesterone administration testifies to the fact that the binding of insulin with its receptors is not a limiting link in the mechanism of insulin action.

[Electrogenic transport of bicarbonate ions through the internal mitochondrial membrane induced by cytoplasmic glycopeptide]. / Elektrogennyi transport ionov bikarbonata cherez vnutrenniuiu membranu mitokhondrii, indutsirovannyi tsitoplazmaticheskim glikopeptidom.

Cytoplasmatic glycopeptide-induced bicarbonate ion electrogenic transport through mitochondrial membrane has been studied. Glycopeptide, described earlier as a factor increasing inner mitochondrial membrane permeability for phosphate ions, has been also shown to induce bicarbonate ion electrogenic transport through inner mitochondrial membrane. HCO3- ion transport, induced by cytoplasm glycopeptide is realized by pH-dependent pore. The interrelation of cytoplasm glycopeptide with mitochondria is regulated by mitochondrial energization.