Vol 62, No 5 (2017)

Cluster–rod structure were designed, which are comprised of tetrahedral atoms with a typical torsion angle of ~38° at interatomic bonds. These structures correspond to a muscle tissue and clathrin lattice by their metrics and topology and can be formed by bound water in these systems. It is shown that the considered rod structures, which are fragments of bound water structures, can also be involved in nondissipative energy transmission as elastic energy storing structures. The estimated length of the bound water rod structure required to absorb the energy of decomposition of an ATP molecule into ADP and a phosphate group is comparable with myosin head sizes and its step along an actin filament. A mechanism of cooperative transition of the rod structure to a fragment of the ice Ih structure was demonstrated. This transition is accompanied by nondissipative release of stored energy.

Transformation of the water cluster distribution in wet potato starch (with a water content of 27 to 45%) at temperatures that ranged from–50 to +80°C was studied by differential scanning calorimetry. A significant difference was observed between the transformations in the temperature ranges below and above 0°C. Both cooling and heating at T < 0°C enabled a reorganization of the initial size distribution of water clusters characteristic for room temperature. These changes could lead to an increase of the average cluster size during both crystallization and melting. The transformation intensity depended on the water content and scanning rate and differed between the native and amorphous states of starch. In this case, the cluster-size distribution remained unimodal. However, heating of wet native starch to temperatures close to the point of transition into the amorphous state (75–80°C) induced a bimodal distribution due to the emergence of large water clusters; thus, the heterogeneity of the water distribution within the native granules increased.

The permeability of ion channels for ions and substances that bind inside the pore depends on the cross-sectional area of the pore. We have constructed models of the closed, open, and desensitized α₁β₂γ₂ GABA_A receptor on the basis of known structures of both prokaryotic and eukaryotic ligand-gated channels. We employed Monte Carlo energy minimization to optimize the model structures. We have found significant pore constrictions, whose diameter depends on the functional state of the receptor in the cytoplasmic, middle, and extracellular parts of the pore-forming M2 segments. It is known that the constrictions in the middle (the 9' ring of residues) and cytoplasmic (the 2' ring of residues) parts of the M2 helices form the activation and desensitization gates of the GABA_A receptor. Our computations predict that the constriction in the extracellular part of the M2 helices (the 20' ring of residues) may also serve as a gate in the GABA_A receptor, whose physiological role is still unclear. Our results imply that the structures of a number of prokaryotic and eukaryotic ligand-gated channels that have been found in bacteria and lower organisms can be used for homology modeling of the pore region of the human GABA_A receptor.

Isolated Helianthus tuberosus L. polysaccharide (HTLP) with a molecular weight of 1–2 MDa has a wide range of biological activities, including the ability to switch transformed cells to an apoptotic pathway. A qualitative explanation for this effect has previously been proposed on the basis of the interactions among components of intracellular signaling pathways associated with the Dectin-1, TLR-6, and TNFR1 receptors and intracellular factors involved in regulating apoptosis. In this work, an autowave model is proposed to explain the switch between alternative modes of cell behavior in response to polysaccharide. The model is based on the modified FitzHugh–Nagumo system of equations. The parameters of the model were estimated numerically.

Intact cells of freshwater algae Cladophora aegagropila (L). Rabenh. (synonymous to Aegagropila linnaei Kutz.) were investigated by resonance Raman spectroscopy. It was found that incubation in the dark (up to 24 h) leads to changes in the Raman spectroscopy spectrum of this species, namely to changes in the ratio of amplitudes of the I₁₅₂₃/I₁₁₅₅ and I₉₆₀/I₁₀₀₄ bands and in the half width of band in the region of 1523 cm–1. We suggested that the adaptation of algae to the dark alters the conformation of the molecule of the carotenoid by delocalization of π-electrons in the polyene chain of the molecule and changes the orientation of the ring. Moreover, the composition of carotenoids, as well as their location in the cell and microenvironment in the pigment–protein complexes can change: in the absence of illumination, the distribution of carotenoids in algal cells is more uniform. These changes are probably caused either by changes in the location of cell organelles or by carotenoid redistribution between photosynthetic membranes, plastoglobules, and lipophilic formations in the cytoplasm.

This review considers the biochemical and biophysical mechanisms that trigger blood clotting upon contact of blood with an alien surface and leads via a cascade of enzymatic reactions to fibrin polymerization and the formation of a blood plasma clot, which permeates a primary platelet aggregate to produce a dense hemostatic clot. In spite of the substantial number of experimental and theoretical studies on the subject, there is still no consistent opinion as to what processes occur as the blood plasma contacts a surface. This review discusses the role that plasma protein factor XII and various surfaces play in triggering the contact pathway in vivo and in vitro. Current views of the molecular events that underlie the process are described.

The enhancement of lipid peroxidation in neutrophils (the content of malonic dialdehyde increased by 10.2%) has been shown after a 1-h exposure to a combined constant (42 μT) magnetic field and a weak low-frequency magnetic field (1.0, 4.4, and 16.5 Hz; 860 nT) collinear to it. No correlation was found between this effect and the process of functional pre-activation (priming) of neutrophils as a result of the combined action of magnetic fields detected by chemiluminescence enhancement in response to the introduction of the bacterial peptide N-formyl–Met–Leu–Phe in the presence of luminol, since ionol (10 μM), an inhibitor of lipid peroxidation, did not reduce the neutrophil priming index in this case. Preliminary addition of histidine (0.1 and 1.0 mM), a singlet oxygen scavenger, also did not decrease the priming index. A myeloperoxidase inhibitor, sodium azide (0.1 mM), exerted a significant inhibitory effect on the chemiluminescence intensity of the neutrophil suspension; priming did not develop in the presence of this inhibitor after the action of combined magnetic fields.

The review is focused on a new, unique and promising method of creating a precision local temperature gradient in the micro- and nanovolumes, allowing to heat a single cell and to explore exogenous and endogenous intracellular processes. Retrospective analysis and systematization of advanced developments in the study of intracellular temperature have been carried out. A device is described in detail consisting of an optical nanoheater, which uses metallic nanoparticles or water warming up with infrared laser beam, enabling setting a stationary temperature gradient of up to 70°C at a distance of 20 μm from the heat source, and a fluorescent microthermometer, which can measure temperature in microvolumes with millisecond resolution. Special attention is paid to the physical, in particular, thermodynamic description of temperature as а parameter of macro-, micro- and nanosystems and to the description of the ultralocal temperature gradient induction mechanism. The results are collected on the implementation of the local heating on living cell and on the thermoinduction of intracellular processes, among which the growth rate of neurites, of about 10 μm/min in a thermal gradient is the most impressive; absolutely new prospects opened by “thermal manipulation” of a living cell are highlighted.

This review describes integrated mathematical models of processes, such as calcium homeostasis, pathogen–host interaction (with hepatitis C virus as a pathogen), and the response of the human brain to a stimulating event. It is shown that integrated mathematical models provide a deeper insight into the mechanisms and conditions that lead to the development of diseases of different natures (musculoskeletal disorders, viral infections, and various impairments in brain function) and aid identification of the key targets and conditions for a directed effect of new generation drugs, as well as the interpretation of the results of state-of-theart CT imaging.

The effect of horizontal clinorotation on the dynamics of the accumulation of the main photosynthetic pigments in the greening of 6-day-old etiolated barley seedlings has been studied. The content of protochlorophillide, the direct precursor of chlorophyll a, in clinorotated seedlings in the dark was 9–20% lower than in the control group. After exposure of barley seedlings to light for 12 h under clinorotation, chlorophyll accumulation lagged behind the control by 45% and reached the control value after 48–72 h. The total content of carotenoids increased many fold during greening; at the first stage the carotenoid level in clinorotated seedlings was less than in the control. The synthesis rates of δ-aminolevulinic acid and δ-aminolevulinate dehydratase activity in clinorotated seedlings were slower than in the control after 24 h of greening and after 72 h of greening reaching the control values. The activity of Mg-protoporphyrin IX chelatase catalyzing the incorporation of Mg ions in the structure of chlorophyll a, did not change when exposed to clinorotation. The results we obtained show inhibition of the initial stages of chlorophyll biosynthesis in the conditions of simulated microgravity. The light, to a certain extent, decreases the negative effect of microgravity on the formation of the photosynthetic apparatus in plants.

A study on the effects of a constant magnetic field on the components of the protein structures in human blood was conducted by the methods of electron spectroscopy, optic aggregometry, and electrophoresis on an agarose gel. It was found that protein structures of different localizations experience the primary effect of a constant magnetic field. As a result, the total charge, form, and linear dimensions of the molecules change, as well as the rotation frequency of the components around valence bonds; this leads to changes in the spatial structures of the blood protein components. It was suggested as a working hypothesis that an increase in the intensity of oxidation processes under the effect of a magnetic field and, consequently, an increase in the negative activities of oxygen metabolites underlie these changes.

Transgenerational genomic instability in the first generation offspring of mice exposed to lowintensity infrared laser (632.8 nm) and light-emitting-diode infrared irradiation (850 nm) was investigated in vivo. It was found that the level of spontaneous damage in bone marrow according to the micronucleus test, the level of reactive oxygen species in whole blood, and the mass index of lymphoid organs in all of the descendants of irradiated mice did not increase. After additional X-ray exposure of the progeny at a dose rate of 1.5 Gy, a decrease in the level of damage and the absence of an adaptive response were revealed upon testing according to “radiosensitivity” and the radiation-induced adaptive-response scheme (0.1 + 1.5 Gy), respectively, compared to the descendants of nonirradiated mice. The rate of tumor growth in the offspring of irradiated mice did not differ from that in the descendants of nonirradiated mice, although inhibition of the tumor growth rate was observed in their irradiated parents. The survival rate after irradiation at a dose rate of 6.5 Gy did not differ from both the parents and the control.

Ischemia-reperfusion injury is a significant problem; there is a need for interpretation of its pathogenetic mechanism and a search for potential methods of correction. The aim of this study was to investigate the cytokine content and the proapoptotic protein expression, including caspase-3, in experimental ischemia–reperfusion injury, and to assess the effectiveness of peroxiredoxin 6 treatment. Studies were conducted on 56 white male Wistar line rats weighing 180–200 g, in which ischemia–reperfusion injury was simulated by cross clamping both hind limbs. Proinflammatory cytokines in blood serum, the expression of caspase-3 in the cells of blood vessels, lungs, and kidneys were analyzed after ischemia–reperfusion injury and upon the peroxiredoxin 6 preventive treatment. It was found that the progression of ischemia–reperfusion injury is followed by proinflammatory cytokine activation in the rat blood: the maximum values of interleukin 1β, which were almost 10 times higher than the control, have been observed by 12 h of reperfusion. Ischemia–reperfusion injury was accompanied by an caspase-3 increase in the cells of rat limb vessels and the lungs after 6 h of reperfusion. Peroxiredoxin 6 treatment neutralizes oxidative stress primarily in the limb blood vessels, reducing the degree of vessel tissue destruction in the hind limbs that should be considered as a target for therapy of ischemia–reperfusion injury.