Volume 68, Nº 4 (2023)

One of the survival strategies evolved by the organisms living in cold ecosystems is production of ice-binding proteins. An important feature of these proteins is to bind to the surface of ice, keep the ice from growing and prevent cells from damage and death. To understand the mechanism underlying interaction between icebinding proteins and ice, it is necessary to know the structure of these extraordinary proteins. This study contributes towards information on the structural and dynamic mechanisms of ice-binding proteins that ensure the adaptation of organisms to extreme conditions. Research on the mechanisms by which ice-binding proteins develop adaptation to cold opens up great opportunities in solving a wide range of interesting problems in medicine, such as the development of effective cryoprotectants for cells and organs, as well as in the food industry, such as long-term food storage without losing nutritional quality at the consumer level.

The interaction of antioxidants - plant polyphenol resveratrol and nitric oxide donor, iron-sulfo-nitrosyl complex with thiosulfate Na₂[Fe₂(S₂O₃)₂(N0)₄]₂4H₂O (TNIC-thio), and their combined action on mitochondria of pea germ epicotyls was studied in vitro. The antioxidant activity of resveratrol (10^-6 M), partially compensated the toxic effect of TNIC-thio at high concentration, that is most likely associated with the exhibition of the prooxidant properties of high concentrations of the nitric oxide donor. The effect of resveratrol at concentrations 10^-6 M and 10^-8 M on the membranes of mitochondria isolated from the pea germ epicotyls treated with 10^-8 M TNIC-thio led to coordinations failure in the system of regulation of lipid peroxidation of membranes, that caused antioxidant stress. The action of resveratrol at the dose of 240^-5 M had a dual character and practically did not effect on the structural state of mitochondrial membranes.

This review provides an overview of molecular mechanisms of intracellular signal transduction involving free radicals. The structure and functions of enzymes that can form superoxide anion-radical and hydrogen peroxide are considered in detail. The mechanisms of regulation of cell properties with the participation of specialized redox chains formed by a group of proteins interacting through electron transport processes are discussed. Genetically mediated mechanisms of regulation of redox cell homeostasis are analyzed. Particular attention is paid to the issue concerning quantitative characterization of the network of interactions of oxidizing and reducing agents, which determines the species and individual characteristics of redox homeostasis and the stress response of cells.

The short-chain fatty acids such as acetic, propionic and butyric acids are microbiota metabolites that can exert a series of physiological effects both in the intestine and other organs, including the central nervous system. The present work aimed to examine the effects of sodium acetate, propionate, and butyrate on the activity of large conductance Ca²⁺ activated K⁺ channels and calcium oscillations in rat pituitary GH3 cells. It has been shown that fatty acids under study cause a dose-dependent increase in the amplitude of total outward potassium currents and these effects are prevented by tetraethylammonium, a Ca²⁺ activated K⁺ channel blocker, indicating the involvement of Ca²⁺ activated K⁺ channels in the effects of fatty acids. It is worthy of note that fatty acids increased open probability of single channels with no changes in the amplitude and the mean channel open time. In addition, fatty acids were associated with a significant reduction in the amplitude and frequency of Ca²⁺ oscillations in GH3 cells. An increase in potassium conductance and a decrease in the intracellular Ca²⁺ level can mediate the effects of short-chain fatty acids in various excitable structures, such as a relaxation of intestinal and vascular smooth muscle cells, hyperpolarization of neurons, and the regulation of hormone and neurotransmitter release.

The release of ATP as an intermediate at the neuromuscular junction, and acetylcholine, the chief neurotransmitter, may take place by mechanisms responsible for quantal and non-quantal secretion from the motor neurons of the central and peripheral nervous system. The dephosphorylation pathway of ATP that is completed by the hydrolysis of AMP to adenosine in the synaptic cleft is a cascade of reactions catalyzed by ectonucleotidases. These enzymes are of enormous interest, the research in this field is necessary to clarify their role in a complex signaling cascade, since it is known that they have dual functions: ectonucleotidases limit the action of ATP as a neurotransmitter and participate in the formation of other neuromodulators (ADP, AMP and adenosine). In addition, ATP and its metabolites can cause completely different physiological effects. The activity of ectonucleatidases in different types of skeletal muscles was determined, it varies within 5-7 IU. A decrease in temperature to 22°C leads to a multiple decrease in the enzymatic regeneration of ATP in skeletal muscle tissues. It is assumed that enzymatic limitation of ATP and the production of its metabolites ensures stabilization of effective cholinergic neuromuscular transmission in norm and pathology.

Clonidine hydrochloride, an agonist of the α2-adrenergic receptor, was tested for its effect on the parameters of the electrical activity of the atrial myocardium induced by pacing. In the experimental rat cardiomyocyte pacing model, clonidine hydrochloride caused a decrease (approximately 50% and 90%) in action potential duration in adult rats. Treatment of one- and three-week-old rats with this agonist led to an increase (around 50% and 90%) in action potential duration

The capability of bioluminescence has been found in many marine hydrobionts, including almost all representatives of the phylum Ctenophora. The glow of species and bioluminescent substrates isolated from them is actively used in biology, ecology, and medicine to study the physiological state of an organism or to identify unfavorable environmental parameters. The parameters of luminescence of the Black Sea ctenophores Mne-miopsis leidyi A. Agassiz, 1865 (Lobata) and Berce ovata Bruguicre, 1789 (Beroida) are used to study the effects of toxicants, such as liquid hydrocarbons, PCBs, and heavy metals. Some researchers casted doubt on the capability of the Black Sea autochthonous inhabitant, ctenophore Pleurobrachia pileus (O. F Muller, 1776) to produce bioluminescent light. The objective of this work was to ensure scientific support for the light-producing ability of species under study and to choose the optimal time for conducting experiments on the factors that affect bioluminescence. It was found that mechanical and chemical stimulation triggered a bioluminescent response in all size groups of species under study at any time of day. Upon chemical stimulation of the studied species, the signal energy value was several times greater than that observed after mechanical stimulation. It was revealed that the optimal time interval for conducting biophysical research is the time from 8 pm to 6 am, because the values of luminescence activity are the greatest in this time interval within a day.

The effects of a non-selective nitric oxide synthase inhibitor L-NAME on the functional parameters of the isolated rat heart after a 30-day period of hypokinesia were studied. Electron paramagnetic resonance spectroscopy was employed in the analysis of a role for L-NAME in the intensity of nitric oxide production in rat heart tissues. The intensity of nitric oxide synthesis was assessed by the intensity of the signal belonging to the (DETC)2-Fe²⁺-NO complex. It was found that L-NAME decreased nitric oxide production on average by 69%. The Langendorff isolated perfused heart was used to evaluate cardiac activity, and the following parameters were measured: pressure generated by the left ventricle, heart rate, and coronary flow. Addition of the nitric oxide synthesis inhibitor L-NAME induced an increase in inotropic function and normalization of heart rate.

Acute kidney injury causes deterioration of liver function, that is a confounding factor affecting treatment outcomes. In this work, renal ischemia reperfusion injury was used as a model. Taking into account that hyperproduction of reactive oxygen species is the major risk factor for kidney damage, the exogenous antioxidant enzyme peroxiredoxin 6, able to neutralize reactive oxygen species, has been used to prevent liver damage when kidneys are damaged. Kidney injury was initiated by a 45-minute ischemia simultaneously with a left-sided donor nephrectomy without manipulations of the liver. Peroxiredoxin 6 was administered intravenously 15 minutes before ischemia. The functional state of the liver was assessed after 2, 5 and 24 hours of reperfusion using histological and biochemical analysis. The signs of liver damage were detected in the best possible way after 5 hours of kidney reperfusion. It was found that peroxiredoxin 6 helps reduce the severity of the vascular reaction and leukocyte infiltration in the liver; lower the level of dystrophy and apoptosis of hepatocytes; keep the concentration of TBA-reactive products even and stabilize the level of cytokines, IL-6 and IL-10, in the liver tissue, as well as normalize the activity of intracellular transferases in the blood at the onset of reperfusion. The protective effect of peroxiredoxin 6 is associated primarily with its antioxidant properties, due to which hyperproduction of reactive oxygen species can be neutralized in the early phase of kidney reperfusion, but the signal-regulatory function of the protein can also contribute to a protective role peroxiredoxin 6.

In the article, based on clinical material obtained in the course of a study of patients with depression, an approach was applied to the analysis of the dependences of electroencephalogram channels using correlation ratios. It can objectively evaluate the properties of connections in any of their models (linear and non-linear). On the basis of the constructed matrices of correlation ratios, the possibility of analyzing paired dependences is shown in order to determination of parameters that differ for the norm and pathology. The direction of the connections between the leads was also established. In our opinion, differences in interhemispheric occipital connections are the most significant. This approach could become the basis for determining unique quantitative markers of depressive states and other neuropsychiatric disorders.

A historical timeline created to celebrate the 63-year anniversary of a chair of biophysics, the first in the world of science chair founded at Lomonosov State Moscow University. Professor Lev Alexandrovich Blumenfeld and Professor Simon El’evich Shnoll, who both departed this life in 2002 and 2021, respectively, started the chair. In the latest issues of journal "Biophysics", a large series of articles written and prepared by friends, colleagues, students, and the successors of these outstanding scientists have been published. This article closes this series. The article includes a brief historical overview of the formation of world and Russian biophysics as a scientific discipline, gives information about the history of how the Chair of Biophysics has been established, its main achievements and the scientific schools formed within the walls of this Department.