卷 73, 编号 3 (2018)

Platelets, or thrombocytes, are important players in inflammation, wound healing, initiation of immune response and regeneration in the organism. Disruption of the blood-brain barrier occurs during certain neurological disorders, such as brain trauma, Alzheimer’s disease or stroke, when blood cells including platelets can invade nervous tissue. However, the role of platelets in the context of neuroinflammation remains understudied. Recent studies have shown that activated platelets release a wide set of coagulative and vascular factors during neurovascular pathologies in the central nervous system. Moreover, platelets stimulate immunity and regulate inflammation in the central nervous system. Trophic and growth factors stored in platelets may play a role in neuronal regeneration. Activated platelets release neurotransmitters, serotonin, dopamine, histamine, and glutamate, and can modify neuronal cell activity in neuropathologies. This review focuses on the major aspects and mechanisms of platelet functions in neuroinflammation, and therapeutic potential of platelets for treatment of neurodegenerative disorders.

Transport of electrons in spinach photosystem II (PSII) whose oxygen-evolving complex (OEC) contains heterogeneous metal clusters 2Mn2Fe and 3Mn1Fe was studied by measuring the fluorescence induction kinetics (FIK). PSII(2Mn,2Fe) and PSII(3Mn,1Fe) preparations were produced using Cadepleted PSII membranes (PSII(–Ca)). It was found that FIK in PSII(2Mn,2Fe) membranes is similar in form to FIK in PSII(–Ca) samples, but the fluorescence yield is lower in PSII(2Mn,2Fe). The results demonstrate that, just as in PSII(–Ca) preparations, there is electron transfer from the metal cluster in the OEC to the primary plastoquinone electron acceptor Q_A. They also show that partial substitution of Mn cations with Fe has no effect on the electron transport on the acceptor side of PSII. Thus, these data demonstrate the possibility of water oxidation either by the heterogeneous metal cluster or just by the manganese dimer. We established that FIK in PSII(3Mn,1Fe) preparations are similar in form to FIK in PSII(2Mn,2Fe) membranes but PSII(3Mn,1Fe) is characterized by a slightly higher maximal fluorescence yield, F_max. The electron transfer rate in PSII(3Mn,1Fe) preparations significantly (by a factor of two) increases in the presence of Ca²⁺, whereas Ca²⁺ has hardly any effect on the electron transport in PSII(2Mn,2Fe) membranes. In Mndepleted PSII membranes, FIK reaches its maximum (the so-called peak K), after which the fluorescence yield starts to decrease as the result of two factors: the oxidation of reduced primary plastoquinone Q_A⁻ and the absence of electron influx from the donor side of PSII. The replacement of Mn cations by Fe in PSII(‒Mn) preparations leads to fluorescence saturation and disappearance of the K peak. This is possibly due to the deceleration of the charge recombination process that takes place between reduced primary electron acceptor Q_A⁻ and oxidized tyrosine Y_Z^+. which is an electron carrier between the OEC and the primary electron donor P680.

Despite the fact that oxidation products of nucleotides and nucleosides are markers of oxidative stress, reports of the paradoxical ability of these compounds to protect cells from the harmful effects of reactive oxygen species began to appear more often. Among all nitrogenous bases, guanine is most susceptible to the influence of oxidative stress; therefore, guanosine is oxidized more often than other bases. In the present work, the effect of exogenous 8-oxo-2′-deoxyguanosine on the growth and “stationary phase aging” (accumulation of “age-related” changes in cultured cells during cell proliferation slowing down within a single passage and subsequent “aging” in the stationary growth phase) of nonsubcultured transformed Chinese hamster cells was studied. We showed that the nucleoside is rapidly absorbed by the cells from the medium, but it does not affect the growth of the culture, and impairs the viability of the cells in the late stationary growth phase. Thus, no mitogenic or geroprotective effect of 8-oxo-2′-deoxyguanosine was found.

Biomass of photosynthetic picoplankton (B_pic), its contribution to the total phytoplankton biomass (B_pic%), chlorophyll a concentration (Chl), and associated hydrophysical characteristics of the water masses in the White Sea were estimated in June 2015 at 47 stations located in the open parts and in the inlets of the Onega and Kandalaksha Bays and in the western part of the Basin. Spatial variability of mean values of B_pic in the photic layer (0.01–1.91 mg C/m³) was preconditioned by sub- and mesoscale heterogeneity of the hydrological conditions. The values of B_pic were higher near the frontal zones than those in the water masses characterized by quasi-homogeneous distribution of the thermohaline characteristics. The relative contribution of B_pic did not exceed 1% at half of the stations and varied from 1 to 8% for the rest of the studied water area. The value of B_pic% reached 40.5% in the Basin and did not exceed 2% during the phytoplankton bloom in Knyazhaya Inlet (Chl > 3 mg/m³) accompanied by the dominance of Skeletonema costatum sensu lato.

Brachiopoda is a relict group of invertebrate filter feeders that used a tentacle organ, lophophore, for capturing food particles from the water column. Brachiopod extinction apparently occurred due to low productivity of their filtering organ in comparison with more advanced filter-feeders. Investigation of the filtering mechanism of modern brachiopods is essential to understanding their evolutionary fate. This study is devoted to the rejection mechanism of large waste particles from the plectolophous lophophore of brachiopod Coptothyris grayi. The waste particles gather inside of the lophophore on the outer side of the brachial fold. The particles form rows along frontal grooves of outer tentacles and are carried successively to the tentacle tips and move along them, slimed by mucus. One portion of the particles comes off the lophophore and falls down the mantle, while another part is carried to the abfrontal surface of the tentacles. Due to repeated reversals of abfrontal cilia, the particles wavily move along the abfrontal surface of tentacles. Such movement contributes to the secretion of mucus and the formation of particle clots. The clots come off the lophophore and fall down the mantle. The particles are transported along the mantle by cilia to the anterior part of the mantle margin. Here the ciliary reversals that facilitate secretion of mucus and formation of pseudofeces also take place. The latter takes away from the mantle cavity. Thus, only outer tentacles participate in the rejection of large waste particles from the lophophore. Ciliary reversals of the abfrontal surface of tentacles and the mantle are discovered in brachiopods for the first time. This facilitates the additional secretion of mucus and formation of pseudofeces, easing their exit from the mantle cavity. The results contribute to the knowledge of lophophore function and evolution of tentacle organs in Bilateria.

A procedure was developed for the preparation of a stalled elongation complex of Escherichia coli RNA polymerase with the nucleosome for investigation by cryo-electron microscopy. We purified the complex from the excess of free RNA polymerase and unproductive complexes on heparin resin and concentrated it on an affine monolayer formed by lipids bound to Ni ions. The use of affinity grids with an immobilized lipid monolayer helps to prevent aggregation of the particles on the grid surface. This technique can be used in the future to obtain a three-dimensional reconstruction of the EC+39 elongation complex.

The effect of different organic compounds (glucose, fructose, ribose, glycine, alanine, pyruvate, acetate, citrate, and yeast extract) as well as of the wastes of food production (molasses, stillage, sweet whey), on the growth of iron-oxidizing acidophilic microorganisms and biooxidation of ferrous iron was studied. Representatives of the microorganisms predominating in biohydrometallurgical processes—archaea of the family Ferroplasmaceae (A. aeolicum V1^T, A. cupricumulans BH2^T, Acidiplasma sp. MBA-1, Ferroplasma acidiphilum B-1) and bacteria of the genus Sulfobacillus (S. thermosulfidooxidans SH 10–1, S. thermotolerans Kr1^T)—were the subjects of the study. All studied strains most actively grew and oxidized ferrous iron in the presence of yeast extract, which is probably due to the presence of a large number of different growth factors in its composition, while others substrates provided growth of microorganisms and ferrous iron oxidation.

Using fluorescence microscopy of single particles with Förster resonance energy transfer recording, structural rearrangements that occurred in nucleosomes formed on the 603 DNA template at high ionic strength were studied. Within the range of 0.7–1.3 M KCl, large-scale changes occurred in the nucleosome structure, including the formation of at least two states differing in the degree of DNA unwrapping from the histone octamer and affecting from 13 to 35 and more pairs of nucleotides. Content of the fraction of nucleosomes with modified structure varied from 60% at 0.7 M KCl to 100% at 1.3 M KCl. Preservation of the association between core histones and DNA in the new conformational states ensured reversibility of structural changes when KCl concentration was reduced to a physiological level. Reversibility was ~100% upon transition from 0.7 M to 0.15 KCl and decreased to ~50% upon transition from 1.3 M to 0.15 KCl.

This paper describes the integrated effect of high summer temperature, intensive insolation, gas pollution, and dust in the air on the pigment content and net oxygen production (apparent photosynthesis) and dark respiration rates of common hibiscus (Hibiscus syriacus L.) leaves. The study included three observation sites: Tashkent Botanical Garden (Academy of Sciences, the Republic of Uzbekistan), the public garden in the central part of the city of Tashkent, and a mountain holiday camp. The research was carried out in 2017 during the period of active vegetation. The results of experiments showed a high adaptive potential of H. syriacus L., as well as its adaptiveness to stress environmental factors of the semiarid zone, provided a sufficient level of its irrigation. The ecological plasticity of the photosynthetic apparatus of hibiscus plays a key role in species adaptation to environmental conditions. It has been revealed that the growth of the plants of the Tashkent Botanical Garden under shading conditions leads to the formation of large, wide, thin, shade leaf blades, which can be considered as the manifestation of sciomorphosis. Heliomorphosis features of hibiscus leaves were identified in mountains, where sun leaves with significantly smaller, thickened, and compacted blades are formed under high insolation. The adaptive significance of these structural leaf modifications is to strengthen photosynthetic capacity for compensating the deficiency in sunlight (in the case of sciomorphosis), and, on the contrary, to provide mutual shading for photosynthetic elements as a measure of protection against the damaging effect of redundant solar radiation (in the case of heliomorphosis). This provides carbon dioxide assimilation and organic matter production for maintaining the constant energy balance for the plant under different environmental conditions. The study of the temperature correlation of dark respiration and net oxygen production rates has shown that these processes are more resistant to temperature injuries under more extreme environmental conditions. In addition, mature H. syriacus leaves have a higher resistance than young leaves; i.e., the plant adapts to possible temperature drops in the process of its ontogenesis. Taking into account the optimal measuring conditions, the net oxygen production rate of H. syriacus during the period of active vegetation is approximately at the same level under different growing conditions (0.20 ± 0.05 μmol of O₂/(dm² s)); this is considered a norm of reaction of the net production (apparent photosynthesis) rate of H. syriacus and determines the specific features of its photosynthetic apparatus.

Pleurozium schreberi is one of the most common moss species in the forest area. It is dominant in the moss layer of blueberry and wood sorrel forests. It can occur in small quantities in almost all types of forests (even in bogs). It is also a typical component of the moss layer in tundra. The article considers the distribution of Pleurozium schreberi in the East European Plain and Eastern Fennoscandia. On the basis of literature sources on the occurrence of the species in different regions (according to point data), a model map of species distribution using the kriging-method has been created. The overlaying of the model map on the maps of spatial distribution of climatic parameters and vegetation zones in this area has revealed that the biogeographical preferences of the species. P. schreberi is characterized by its highest distribution in the forest zone. It often occurs here and represents a phytocenotically active species. The occurrence of Pleurozium schreberi dramatically decreases in the transition from the forest to the steppe zone, where it is a rather rare species, growing exclusively in pine and birch pegs. This species disappears in the open steppe. From the steppe zone to the south, the occurrence of Pleurozium schreberi gradually decreases with increase in summer temperatures and decrease in precipitation and with forest disappearance. In the north, where the species is highly active, its range abruptly ends on the coast of the Arctic Ocean. This pattern of distribution of Pleurozium schreberi is associated both with cenotic preferences and with climate: it becomes rare in regions with summer temperatures higher than +23°C and annual precipitation of less than 400 mm.