bluuebunny/crossref_metadata_2025 huggingface dataset:
Conformational Rearrangements of Adsorbed Polyampholytes under Periodic Changes in Polarity
of a Charged Prolate Gold Nanospheroid
Authors: Kruchinin N. Yu. , Kucherenko M. G. , Neyasov P. P.
Published: April 2024

Conformational rearrangements of polyampholytic polypeptides adsorbed on the surface of a charged prolate gold nanospheroid with a periodic change in time of its polarity along the rotation axis have been studied using molecular dynamics simulation. The radial distributions of the density of polypeptide atoms in the equatorial region of the nanospheroid have been calculated, as well as the distributions of the linear density of polypeptide atoms along the major axis of the nanospheroid. At a low simulation temperature, a girdle polyampholytic fringe was formed in the central region of the nanospheroid and its ordering by layers, depending on the type of units, occurred with an increase in the charge of the nanospheroid with a simultaneous increase in the width of the macromolecular fringe along the rotation axis. The thickness of such a fringe along the cross section depends on the distance between the oppositely charged units in thepolyampholyte. At high temperatures and high absolute values of the total charge of the spheroidal nanoparticle, there were periodic displacements of the polyampholytic fringe toward the poles of the nanospheroid, being in antiphase for oppositely charged metallic nanospheroids. A mathematical model is presented for describing the conformational structure of a polyampholyte macromolecule on a prolate nanospheroid in an alternating electric field with the approximation of a prolate spheroid by a spherical cylinder
Mathematical Model and Experimental Data for Water Cooling in Counterflow Film Cooling Towers
Authors: Lapteva E. A. , Laptev A. G.
Published: April 2024

The article considers the research methods, mathematical simulation, and calculation of heat-and-mass-transfer characteristics of film-type fills (packings) of cooling towers. The basic research approaches include experimental, numerical, and approximate methods. It is noted that the experimental and approximate methods are the most applicable for practical purposes when calculating cooling towers. One of the approximate methods consists in the application of flow structure models, namely, diffusion or cellular models. The authors consider the application of the cellular model for the gas and liquid phases in the form of an analytical solution with the thermal number of transfer units to calculate the thermal efficiency of the gas phase (air heating) and determine further the efficiency of the cooling water based on the thermal balance equation. The main parameters of the model, namely the number of cells for the gas and liquid phases, are calculated using the presented expressions. The article presents experimental data on hydraulic resistance, the volumetric coefficient of mass transfer, and thermal efficiency in the gas and liquid phases, obtained using the experimental model of a cooling tower with a bank of tubes (fill pack) with a discrete-regular rough surface. The calculation results by the cellular model are shown to agree with the experimental data. In addition, the calculation is performed for mini cooling towers with regular fills, used in rectification and absorption columns.
Method to Calculate the Limiting and Optimal Conditions of the Chemical and Energy Engineering Process of Calcination of Lump and Pelletized Phosphate Ore Raw Materials on the Grate of a Traveling-Grate Roasting Machine
Authors: Meshalkin V. P. , Orekhov V. A. , Dli M. I. , Bobkov V. I. , Chistyakova T. B.
Published: April 2024

A method and a mathematical model were proposed to calculate the chemical and energy engineering process of roasting of phosphate ore raw materials in a moving dense bed on the grate of a traveling-grate roasting machine. The results of computational experiments on the developed computer model were used to analyze the limiting and optimal conditions of drying and roasting of lump and pelletized phosphate ore raw materials on the traveling grate of the roasting machine. The limiting conditions for the calcination of lump and pelletized ore raw materials loaded as a monolayer bed of lumps, for co-roasting, and as a bed of phosphorite pellets were determined taking into account the technological restrictions on the existing traveling-grate roasting machines. For phosphate ore raw materials, it was determined that the maximum achievable degree of decarbonization in high-temperature roasting of lumps in the traveling-grate roasting machine is 60%, whereas the pellets can be roasted to a degree of decarbonization of 80%. The method of thermophysical and kinetic studies that was proposed in this paper can be extended to study the laws of thermally activated endothermic chemical-metallurgical calcination processes in a wide class of iron ore raw materials. The presented computer model for calculating the limiting and optimal conditions for the operation of traveling-grate roasting machines is used for the rapid adaptation of industrial plants to the periodically changing properties of ore raw materials supplied for heat treatment.
Reproducibility of the Results of the Conductometric Determination of the Degree of Dilution of the Essentuki-4 Mineral Water
Authors: Nikulina S. N. , Smirnova E. I. , Vasyukov A. E. , Fateeva N. Yu. , Cherikanova E. A.
Published: April 2024

Calculations substantiated the reproducibility of the conductometric method for the quantitative determination of the volume concentration of water added to the Essentuki-4 mineral water by analyzing the dependence of the specific electrical conductivity of the mineral water and model solutions prepared on the basis of it. The method fully complies with the principles of green chemistry, since the “waste” is mineral water diluted with distilled water.
Evaluation of the Efficiency of the Separation of Dust–Gas Flows in Uniflow Cyclones
Authors: Toptalov V. S. , Chesnokov Yu. G. , Meshalkin V. P. , Kulov N. N. , Flisyuk O. M. , Martsulevich N. A. , Likhachev I. G.
Published: April 2024

A model was proposed for determining the efficiency of fractional separation in a uniflow cyclone. The model includes parameters that characterize the motion of a particle in the cyclone and, hence, the degree of separation, namely, the distance that the particle travels when moving in a helical path, and this path itself. The separation efficiency in a uniflow cyclone of a new design was experimentally studied. The experiments were carried out with quartz flour of four particle size fractions: 15, 20, 30, and 50 μm. The efficiency of the cyclone in the separation of small particles was high for apparatuses of this type. The separation efficiency curves were analyzed.
The Role of Energodynamics in the Scientific Bases of Chemical Technology
Authors: Dorokhov I. N.
Published: April 2024

The article presents a compact and exhaustive interpretation of the foundations of energodynamics and shows that it significantly extends the horizons of natural science and opens new avenues to improve the scientific bases of chemical technology.
Enhancement of Heat Transfer in a Tube Channel of a Tubular Heat Exchanger
Authors: Konoplev A. A. , Rytov B. L. , Berlin Al. Al. , Romanov S. V.
Published: April 2024

Thermal engineering experiments were carried out with laboratory water-to-water tube-in-tube heat exchangers of the same design parameters with smooth and profiled inner tubes. The tubes were profiled by confuser–diffuser constrictions of the flow section of the inner channel, which were formed by the deformation of their walls and placed along the length at a step that was constant and equal for all profiled tubes. The obtained results showed a dependence of the heat transfer enhancement in the tube channel on the Reynolds and Prandtl numbers, with the dependence on the latter being much stronger than that on the former, at least in cases where the heat carrier is water.
Theory of a Solid–Liquid Heterogeneous Reaction to Form a Gas Phase
Authors: Meshalkin V. P. , Orekhov V. A. , Bykov A. A. , Bobkov V. I. , Shinkevich A. I.
Published: April 2024

An analytical model of a solid–liquid heterogeneous reaction to form a gas phase was presented. The model is based on the analysis of the main parameters that have the most significant effect on the intensity of the reaction. The formation of gas–liquid dissipative structures in the form of alternating flows of reacting phases that perform relaxation pulsations was shown. The formation, detachment, and movement of bubbles were described with a satisfactory adequacy. The dynamics and conditions for the formation of a gas bubble on a solid reaction surface were characterized. Relationships were obtained for estimating the mass-transfer coefficients, which correlate with experimental data. The developed analytical model of the heterogeneous reaction will give a better insight into the essence of the melting processes in ore-thermal furnaces, which will make it possible to make changes to these processes using qualitatively new parameters of their characteristic reactions. Analysis of the hydrodynamics with the formation of the gas phase by analytical and numerical methods suggested the type of the flow of the liquid phase. Typical was the presence of hydrodynamic structures that determined the ordered movement of the liquid phase with various methods of supplying the gas phase. The values of critical mass-transfer parameters were determined. In contrast to the boiling process, a crisis of the heterogeneous reaction is impossible because of the shielding of the reaction surface.
A Study of the Effect of Pressure on the Relative Volatility of the Components in the Process of Rectification of Mixtures of Different Natures
Authors: Gaganov I. S. , Frolkova A. V. , Frolkova A. K.
Published: April 2024

The effect of pressure on the coefficient of relative volatility of binary mixtures of different natures and ternary mixtures containing potential separating agents such as dimethylsulfoxide (DMSO) and butyl propionate is studied. A wide range of information is obtained based on the data on the vapor–liquid equilibrium, and effects of the pressure on the relative volatility of various nature and cause for a fixed composition of the initial mixture are determined. In the presence of points of intersection of the phase-equilibrium curves in the initial binary mixture and pseudobinary mixture (in the section with a constant concentration of the third high-boiling component), the concentration simplex is divided into regions in which the values of the coefficient of relative volatility decrease (increase) upon varying pressure. This fact makes it possible to improve the procedure of optimization of the process of separation at the stage of selection of the working pressure in the columns.
Denitrogenation of Light Hydrocarbon Fractions with Natural Deep Eutectic Solvents Using Commercial Extraction Equipment
Authors: Lobovich D. V. , Solov’eva S. V. , Milevskii N. A. , Zakhodyaeva Yu. A. , Voshkin A. A.
Published: April 2024

Hydrophilic deep eutectic solvents are actively positioned as efficient extractants for removing heterocyclic compounds from light hydrocarbon fractions. Of particular interest is the subclass of natural deep eutectic solvents (NaDESs), since they contain substances of exclusively natural origin. However, these processes have not been systematically studied to date in extraction equipment. To study the process of countercurrent extraction of pyridine, quinoline, and indole from a model solution of light hydrocarbon fractionsusing commercial equipment, a series of NaDESs based on citric and malic acids, xylitol, and water was used for the first time in this work. The high extraction capacity of these NaDES was demonstrated in laboratory experiments, and the extraction mechanism was determined. A detailed study of the efficiency of extraction of heterocycles with varying process conditions allowed us to move on to studying the process using extractorsof the mixer–settler type. From the model solution of light hydrocarbon fractions, pyridine, quinoline, and indole were removed to concentrations 1 ppm by countercurrent extraction using a cascade of six mixer–settlers.
Separation of Industrial Mixture of Decalin or Naphthalene Fluorination Products. Physical-Chemical Foundations of Crystallizing Binary Mixtures of cis- and trans-Perfluorodecalin and Perfluorobutylcyclohexane
Authors: Polkovnichenko A. V. , Kulov N. N. , Kisel’ A. V. , Kuritsyn N. N. , Kvashnin S. Ya. , Lunachev E. V.
Published: April 2024

Physical–chemical data on the liquid–solid phase transitions in the binary systems trans-PFD–cis-PFD, trans-PFD–BCH, and cis-PFD–BCH are obtained. All three systems are characterized by the presence of a temperature extremum on the fusibility curve. For the trans-PFD–BCH system, the liquidus line can be described by the equation for simple eutectic systems with the assumed activity coefficient = 1, which indicates that the behavior of the system is close to ideal. The process of bulk crystallization is considered using the example of a cis-PFD–BCH mixture. It is demonstrated that from cis-PFD–BCH mixtureswith an initial content xcis-PFD = 0.7348 and 0.6447 mol. fr., cis-PFD can be isolated with a purity of more than 0.99 mol. fr. in three crystallization cycles.
Simulation Methods to Model Chemical Processes at Elevated Pressures and the Theory of Non-ideal Reaction Systems
Authors: Tovbin Yu. K.
Published: April 2024

Literature analysis shows that the main method to model the equilibrium characteristics of reaction systems at elevated pressures, including processes under supercritical conditions, are equations of state describing the non-ideality of the vapor and liquid phases, while the law of mass action is applied to describe the kinetics of the elementary and chemical stages. The mentioned difference in the types of models used to describe the equilibrium and kinetic characteristics of the same experimental system under study violates thesecond law of thermodynamics formulated by Clausius. The only theoretical method consistent with the second law of thermodynamics is the molecular theory based on the lattice gas model. In order to satisfy the second law of thermodynamics, molecular models must provide the self-consistent description of the rates of the chemical process at the equilibrium and elementary stages. This means that the molecular models must providea single mathematical apparatus to calculate the states of the system both outside and inside the equilibrium point. The molecular models can differ in both the effective parameters of the interparticle interaction and the methods of refining these models due to taking into account distinctions in sizes, contributions of the vibrational motions of the components, as well as the accuracy of description of the correlation effects. To ensure the self-consistent description of the equilibrium and kinetics, the models must at least reflect the effects of direct correlations. One-particle approximations (mean field, chaotic, density functional) do not correspond to the self-consistency condition and violate the second law of thermodynamics.
Cytotoxic Activity of Atmospheric Cold Plasma Jet Towards 3D Human Breast Cancer Cell Model
Authors: Patrakova E. A. , Birykov M. M. , Troitskaya O. S. , Novak D. D. , Milakhina E. V. , Gugin P. P. , Zakrevskyc D. E. , Schweigert I. V. , Koval O. A.
Published: April 2024

The treatment of solid tumors with a cold atmospheric plasma jet (CAP) is an innovative approach, which began to be actively developed only in the last decade. As a consequence, the studies aimed at revealing the conditions of selectivity of such effects on tumor cells, including in 3D tumor models, are important. It is known that the main cytotoxic effects of CAP are caused by reactive oxygen and nitrogen species, which are formed in the plasma flow and the availability of which for the cells in the classical 2D and 3D cultivation models may be different. We used multicellular spheroids of MCF7-EGFR cells with hyperexpression of epidermal growth factor receptor (EGFR), the parental MCF7 breast adenocarcinoma cell line, and MCF10A non-transformed human breast cells. Irradiation of MCF7-EGFR spheroids led to destruction of multicellular 3D structures into individual cells with activation of death processes. It was shown that cells of CAP-irradiated spheroids underwent phagocytosis by activated macrophages. When comparing direct exposure to CAP and cultivation of MCF7-EGFR spheroids in CAP-irradiated medium (CAP-IM), a higher content of reactive oxygen and nitrogen species in spheroid cells was found when cultured in CAP-IM, which further leads to a greater cytotoxic effect than in direct irradiation. The cytotoxicity of CAP-IM has been shown to be valid longer when such medium is stored at 4 than at −20°С. Thus, it was shown that the treatment of spheroids with CAP-IM was more effective in death induction than direct CAP irradiation.
The Role of the Notch Signaling Pathway in the Pathogenesis of Lung Diseases of Non-infectious Etiology
Authors: Serebryakova V. A. , Sanina A. E. , Urazova O. I. , Gadzhiev A. A. , Stepanova E. P.
Published: April 2024

A review of current literature data on the significance of the Notch signaling pathway in the mechanisms of the development of diseases of the respiratory system – chronic obstructive pulmonary disease (COPD), bronchial asthma (BA) and lung cancer is presented. In studies of lung tissue samples of patients with COPD and lung tissues of mice, it was found that activation of the Notch signaling pathway promotes metaplasia and increases the functional activity of goblet cells, protects epithelial cells from apoptosis and oxidative stress. Suppression of the Notch−Jagged1/Jagged2 pathway is associated with the transdifferentiation of club-shaped cells into ciliated ones. In patients with AD, the Notch signaling pathway promotes differentiation of Th2 lymphocytes. In the ovalbumin-induced bronchial asthma model, the Notch cascade increases the imbalance of Th17/Treg lymphocyte populations, the production of IL-4, IL-5, IL-13, IL-17, the formation of allergen-specific IgE, eosinophilic infiltration and metaplasia of goblet-shaped epithelial cells of the respiratory tract. A decrease in the concentration of IgE, Th2-type cytokines (IL-4, IL‑5, IL-13), an increase in the number of Treg cells and the level of TGFß in bronchoalveolar lavage in mice with asthma, mediated by the introduction of dendritic cells expressing the ligands DLL1 and Jagged1, indicates the protective role of the Notch signaling pathway. On samples of tumor tissue and cell lines of non-small cell lung cancer, it was found that an increase in the expression of Notch-1 and Notch-3 mRNA is associated with increased proliferative activity, malignant cell transformation, a high risk of metastasis to lymph nodes and an unfavorable prognosis of the disease. In the samples of tumor tissue of small cell lung cancer, an increase in the expression of the Notch ligand DLK1 signaling inhibitor gene, the Ascl1 transcription factor gene and lysine-specific histone demethylase 1 (LSD1) was recorded. Suppression of LSD1 activity is accompanied by reactivation of signaling via Notch-1 receptor and subsequent inhibition of the transcription factor Ascl1, which induces the initial stages of tumor transformation.
Development of Method for Three-Dimensional Cultivation of Human Mesenchymal Stem/Stromal Cells Using Cellulose Scaffolds
Authors: Kuneev I. K. , Ivanova J. S. , Nashchekina Y. A. , Patronova E. K. , Sokolova A. V. , Domnina A. P.
Published: April 2024

The development of methods for culturing cells in three-dimensional systems is an urgent focus of modern cell biology. When cultured in the 3D system, a tissue-specific architecture is reproduced and the real microenvironment and cell behavior in vivo are more precisely recreated. Human mesenchymal stem/stromal cells (MSCs) are typically isolated and cultured as a monolayer 2D culture. In this work, we developed a method for three-dimensional cultivation and tissue-specific decidual differentiation of MSCs isolated from human endometrial tissue using a matrix derived from decellularized apple. Decellularized apple matrices have sufficient mechanical strength, are biocompatible, accessible, easy to use, and have ample scope for surface modification. This cell culture system is suitable for both confocal microscopy and flow cytometry studies. The model we developed can become the basis for the creation of new cell products and tissue-engineering structures in the field of regenerative biomedicine.
Pericytes as an Essential Part in Transwell Models of the BBB in Vitro
Authors: Mosiagina А. I. , Khilazheva E. D. , Morgun A. V.
Published: April 2024

In this study we aimed to demonstrate the advantages of using a quadruple culture model of the blood-brain barrier (BBB) in vitro in comparison with a common triple culture model, as well as to show the impact of pericytes on endothelial cells of the BBB. We co-cultured primary rat brain microvascular endothelial cells (BMECs), pericytes, astrocytes and neurons in a Transwell BBB model in vitro. Then, we carried out quantitative analysis to compare transendothelial electrical resistance (TEER) values, as well as expression levels of tight junction proteins, ZO1 and JAM1, in the triple culture and the quadruple culture Transwell BBB models in vitro. According to the obtained data, the quadruple culture model of the BBB in vitro has advantages over the triple culture model, since the presence of pericytes is accompanied by higher TEER values and higher expression levels of tight junction proteins in endothelial cells. The results presented in the study are consistent with the world scientific literature and confirm the hypothesis that pericytes not only offer mechanical support for endothelial cells, but also play a key role in signaling networks between different cell types of the neurovascular unit (NVU) and thus regulate the barrier functions of the BBB. According to this, co-culture of BMECs, astrocytes, and neurons with pericytes is essential for BMECs optimum phenotype and offers a closer representation of the in vivo environment.
Activation of Endogenous Mesenchymal Stromal Cells as an Approach to Tissue Regeneration
Authors: Payushina O. V. , Tsomartova D. A. , Chereshneva Ye. V. , Ivanova M. Yu. , Lomanovskaya T. A. , Pavlova M. S. , Kuznetsov S. L.
Published: April 2024

Mesenchymal stromal cells (MSCs) which have a complex pro-regenerative effect on damaged tissues represent a promising resource for cell therapy for a wide range of diseases. However, transplantation of autologous or donor MSCs to a patient is associated with a number of problems, such as variability of cell properties depending on their source and cultivation conditions, a decrease in their therapeutic potential and the possibility of acquiring immunogenicity or tumorigenicity during in vitro expansion, and the invasiveness of the isolation procedure. One of the ways to avoid these problems can be the impact on endogenous MSCs by stimulating their directed migration into tissue defects, without the need for extraction from the body, in vitro cultivation and reintroduction to the patient. This review discusses approaches to activating the mobilization of MSCs from tissue niches and/or stimulating their migration to the target area, which can be considered as a safer, and possibly more effective alternative to MSC transplantation.
Growth and Molecular Characteristics of Temozolomide-Resistant Human A172 and R1 Glioblastoma Cells
Authors: Pinevich A. A. , Vartanyan N. L. , Kartashev A. V. , Kiseleva L. N. , Smirnov I. V. , Sidorova Z. U. , Svitina S. P. , Samoilovich M. P.
Published: April 2024

Glioblastoma recurrence is caused by initial and acquired as a result of therapy resistance of tumor cells. Studies searching the markers that would allow predicting the level of glioblastoma cell resistance to therapy are in progress. The complexity of the problem is related to the high heterogeneity of individual tumors and the cellular content of each tumor. In present work, a comparative study of the influence of single temozolomide (in Temodal® form) ex-posure on the well-known glioblastoma cell line A172 and a new one R1 was performed. In A172 (highly tem-ozolomide-sensitive cell line) after treatment with 0.1 mM of this drug only individual cells persisted and resumed proliferation. In R1 glioblastoma cell line single cells survived and resumed proliferation after treatment with 1 mM temozolomide. The populations resulting from the proliferation of these cells were designated as resistant. The expression of MGMT, as well as genes responsible for resistance to chemotherapy and tumor progression (MGMT, ABCB1, ABCC1, ABCG2), growth factor genes (VEGF, HGF), cytokines IL-6 and IL-8, and their encoding genes was examined in resistant A172 and R1 cells. In A172 cells, the methylated status of MGMT gene promoter was confirmed, as well as the absence of the corresponding gene expression. It was shown for the first time that glioblastoma R1 is heterogeneous by the methylation status of MGMT gene promoter and expression of the relevant enzyme. In A172 and R1 resistant cell populations, the level of MGMT gene promoter methylation was lower than in the intact cells, and MGMT gene expression was enhanced. We suspect that this may be the reason for greater resistance of such cells to chemotherapy. The expression of most genes associated with resistance to chemotherapy and a more aggressive course of the disease, genes of growth factors, and interleukins in resistant A172 cells was higher than in intact cells. In contrast, in resistant R1 cells, the expression of most of the same genes (with the exception of ABCC1 and VEGF, for which the expression level changed insignificantly) was lower than in the intact cells. These results confirm the significance of MGMT in the formation of glioblastoma cell resistance to temozolomide. The prognostic value of the other studied parameters is still ambiguous.
Impact of the Stimulation and Inhibition of NAD+ Biosynthesis on the Maintenance of Pluripotency in Mouse Embryonic Stem Cells
Authors: Antipova M. V. , Kulikova V. A. , Solovjeva L. V. , Kropotov A. V. , Svetlova M. P. , Yakimov A. P. , Nerinovski K. B. , Bakhmet E. I. , Nikiforov A. A.
Published: April 2024

Nicotinamide adenine dinucleotide (NAD+) plays a key role in cellular metabolism and signaling. In recent years, evidence has accumulated that NAD+-dependent processes are involved in the regulation of pluripotency and differentiation of mammalian embryonic stem cells. The major means to maintain NAD+ levels in mammalian cells is through its biosynthesis from various forms of vitamin B3. In this study, we examined how stimulation and inhibition of NAD+ biosynthesis affect the maintenance of the pluripotency of mouse embryonic stem cells E14 Tg2a (E14 cells). The pluripotency status of E14 cells was assessed by immunocytochemical and immunoblotting analysis using antibodies to the pluripotency factor Oct4, as well as by staining for alkaline phosphatase. Using NMR spectroscopy, we have found that the concentration of NAD+ in pluripotent E14 cells cultured in the presence of LIF is about 4 nmol/mg, and it remains unchanged after induction of differentiation with retinoic acid. We have also demonstrated that pharmacological stimulation of NAD+ biosynthesis by nicotinamide riboside increases the level of intracellular NAD+ by 20%, but it does not affect the maintenance of pluripotency in E14 cells. Moreover, under conditions of critical depletion of NAD+ pool by Nampt inhibition with FK866 E14 cells maintained pluripotency, though the expression level of Oct4 was decreased.
Titanium Dioxide Nanoparticles Inhibits Entosis in the Human Breast Adenocarcinoma Cell Line
Authors: Kisurina-Evgenieva O. P. , Savitskaya M. A. , Smeshnova D. S. , Onishchenko G. E.
Published: April 2024

TiO2 is widely used in industry and cosmetics and medicines production. In recent years, to achieve tumor-specific delivery of anticancer agents, TiO2 nanoparticles have been used in chemo/photodynamic therapy, which may cause local increase of the TiO2 concentration in tumors. The TiO2 nanoparticles can affect various processes in tumors. One of such process is entosis. During entosis one tumor cell invades another tumor cell. The aim of this work was to study the effect of TiO2 nanoparticles (anatase 25 nm and rutil/anatase 75 nm; 1, 10 and 100 µg/mL, 72 hours) on the entosis in the human breast adenocarcinoma cell line (MCF7). Cultivation of cells in the presence of nanoparticles lead to a slowdown in proliferation and reduced in the entosis number. These effects were dose-dependent. Elemental analysis (analytical electron microscopy) showed presence TiO2 nanoparticles in the cell vacuoles, in the cytosol and in the extracellular space. TiO2 nanoparticles (10 µg/mL) significantly disrupted adhesive junctions in entotic cells and in cell culture in general (immunocytochemistry staining). The anatase nanoparticles induced p53 translocation into the nucleus. Thus, the obtained data showed that the TiO2 nanoparticles inhibited entosis in MCF-7 cells by means of disrupting the adhesive junction formation and preventing cell invasion. However, failure of adhesive contacts can facilitate tumor metastasis.
Visualization of Escherichia coli Single Cells in the State of SOS Response Using Expansion Microscopy
Authors: Rumyantseva N. A. , Golofeeva D. M. , Vishnyakov I. E. , Vedyaykin A. D.
Published: April 2024

Expansion microscopy (ExM) is a sample preparation method that allows to achieve improved visualization of structures due to the physical expansion of the sample. This method is used in combination with traditional light microscopy and allows, without the use of complex technical devices typical for super-resolution microscopy, to achieve visualization of biological structures with higher resolution. Unlike the methods of super-resolution microscopy, expansion microscopy does not make it possible to overcome the diffraction limit; however, the observed effect can be considered equivalent to an increase in the spatial resolution. The relative simplicity of the method and the undemanding nature of the microscope used have made expansion microscopy a fairly popular method to visualize various biological structures last time. This paper describes the use of expansion microscopy to visualize DNA and structures formed by the FtsZ protein in Escherichia coli cells during the SOS response. The results of the work confirm the previously obtained data that the FtsZ protein in cells in the state of the SOS response is unevenly distributed. The protocol used in this work for visualization of E. coli cells preliminarily fixed on the glass surface using the expansion microscopy method can be used in the future to study the internal structures of other cells, both bacterial and eukaryotic.
New in Centromere Genomics: Lessons from the First T2T Human Genome Assembly
Authors: Uralsky L. I. , Alexandrov I. A. , Ryabov F. D. , Lapidus A. L. , Rogaev E. I.
Published: April 2024

With the recent development of long-read sequencing technologies, it is now possible for the first time to read a complete gapless sequence of the human genome. The result was the first T2T (telomere-to-telomere) genomic assembly, published by an international consortium of scientists in 2022. The most significant contribution of the new assembly were the centromeric regions consisting of highly repetitive satellite DNA. In this review, we will briefly list the major achievements of the T2T consortium related to centromeres and take a closer look at the unexpected findings of cytogenetic magnitude that analysis of first assembled human centromeres has brought, such as the “split” centromeres of chromosomes 3 and 4, mega-inversion in the active centromere array of chromosome 1, haplotypic epialleles in the centromere of X chromosome and the macro-repeats found in several centromeres.
The Role of the Integrated Response of Tumor Cells to Stress, Autophagy, and Chaperones in the Origin of Recurrent Resistant Tumors
Authors: Zubova S. G. , Gnedina O. O.
Published: April 2024

Chemotherapy and radiotherapy are a colossal stress factor for tumor cells. In response to therapy, the entire evolutionarily fixed response of cells to stress is activated. This happens at all levels of cell organization, namely at the protein level and the DNA level. This response involves the cell proteostasis system, DNA repair systems, tumor suppressor genes, and many other cell systems. We will consider the role of the main systems of proteostasis in these processes, namely, macroautophagy and chaperones, which are part of the integrated response of the cell to stress. As a result of the cell’s response to stress, the tumor cell becomes even less differentiated, activating the genes and intracellular systems necessary for survival. Cells that have responded to stress in this way have a more aggressive phenotype that is significantly more resistant to therapy. Under the influence of stress, the cell evolutionarily simplifies, which gives it additional chances for survival. On the one hand, autophagy contributes to a decrease in tumor cell differentiation and its plasticity, and on the other hand, it maintains a certain stability, being responsible for the integrity of the genome and freeing the cell from damaged organelles and defective proteins. Both autophagy and chaperones contribute to the acquisition of multidrug resistance by the tumor, which further complicates therapy. Understanding these processes makes it possible to develop new therapeutic approaches, taking into account the multistage nature of carcinogenesis.
Synaptophysin Expression by Supraependymal Structures of the Rat Brain
Authors: Razenkova V. A. , Kirik O. V.
Published: April 2024

Supraependymal plexus in ventricular system is one of the most cryptic structures in the mammalian central nervous system. Since both the topography of supraependymal elements and their functional role remain unclear, the aim of this research was to study the distribution of supraependymal structures within the ventricular system of the rat brain with synaptic function associated marker, synaptophysin. Serial sections of Wistar rats (4–6 month, n = 6) forebrain were examined using immunohistochemical detection of synaptophysin and tyrosine hydroxylase. It was shown that supraependymal plexus can form on the surface of ependymal cells synaptophysin-immunopostitive discrete structures, which indicates the formation of synaptic contacts. Although catecholaminergic nerve fibers were present on the ventricular surface in all studied zones, it seems that these nerve fibers may not always contain synaptophysin. Thus, it is assumed that the functional purpose of the supraependymal nerve plexus depends on its localization and can be associated whether with the regulation of ependymal cells and cerebrospinal fluid formation, or with the formation of long-range interneuronal connectivities.
Tyramide Signal Amplification: New Opportunities for DNA In Situ Hybridization
Authors: Vorontsova E. О. , Yurchenko D. A. , Shilova N. V.
Published: April 2024

DNA in situ hybridization (DNA-ISH) is a widely used method in molecular cytogenetics that allows the localization of specific DNA sequences in particular regions of chromosomes. Implementation of DNA-ISH requires the use of DNA probes, which can be commercial or developed for specific research purposes as non-commercial (homemade) DNA probes. One of the significant drawbacks of non-commercial probes is the difficulty in obtaining a high signal intensity with a small DNA probe size. Therefore, developing approaches to enhance non-commercial DNA probes is an important task in modern molecular cytogenetics. To directly visualize small DNA sequences on a chromosome, the tyramide signal amplification (TSA) method is used. The TSA system is based on the formation of a covalent bond between electron-rich protein fragments in the sample and tyramide molecules linked to a hapten (in chromogenic in situ hybridization) or a fluorophore (in fluorescent in situ hybridization). This is achieved by converting tyramide molecules into free-radical intermediate compounds under the action of horseradish peroxidase (HRP), followed by deposition of precipitated molecules nearby. As a result, a low-intensity signal is amplified. Thus, TSA is a good complement to the DNA-ISH method, thanks to its high sensitivity and ability to detect small genomic imbalances, and can therefore become a valuable tool for diagnosing chromosomal rearrangements in clinical practice.
Functional Interactions of BAF and LEM Proteins in the Formation of Germ Cells
Authors: Bogolyubova I. O. , Bogolyubov D. S.
Published: April 2024

Recovery of the nuclear structure after cell division requires special interactions between the integral proteins of the inner nuclear membrane having a special LEM domain (LEMD), nuclear lamina proteins (lamins) and the conserved BAF protein that serves as a central link in these interactions, providing topological relationships between chromatin and nuclear envelope. The dynamic transformations of these protein ensembles in the mitotic cycle are characterized in detail at the molecular level, however, less attention is paid to the developing germ cells undergoing meiotic divisions, despite of their nuclei, especially in diplotene oocytes, differ significantly in structure from the somatic nucleus. This review summarizes the still relatively scarce experimental data proving the significance of functional interactions between BAF and LEMD proteins for gamete formation, from the selection of germline cells to the transformation of haploid spermatids into morphologically mature spermatozoa.
The Intensity of Degradation and Synthesis of Derma Intercellular Matrix in Rats after Local Cold Injury in the Presence of Metabolic Syndrome
Authors: Shutskiy N. A. , Gorbatova L. N. , Kashutin S. L. , Kholopov N. S. , Shagrov L. L. , Zashihin A. L.
Published: April 2024

Studies of tissue regeneration processes in the post-cold period are currently in demand in connection with the development of the Arctic, which is characterized by extremely low temperatures. Metabolic or hormonal abnormalities based on insulin resistance and compensatory hyperinsulinemia, which can lead to the development of cardiovascular diseases, and, consequently, to microcirculation disorders, are aggravating factors that increase the consequences of cold injuries. In this work, we studied the processes of degradation and synthesis of the intercellular matrix of the dermis, as well as the concentration of sialic acids in the blood serum after a local cold injury of the third degree. It was revealed that the regenerative process after local cold damage began on day 3 and was characterized by an increase in the collagen content of the dermis and the thickness of collagen fibers. Regeneration in the case of metabolic syndrome was accompanied by a slowdown in tissue repair processes. The course of the recovery process was associated with a change in the content of sialic acids in the blood serum, while a distinctive feature of the dynamics of this indicator was an increase in the concentration of sialic acids in metabolic disorders on day 7 and a slow slight decrease throughout the experiment, reaching the control values by day 21.
Gap Junction Protein Connexin-43 in Glial Cells of Rat Dorsal Root Ganglion
Authors: Kolos E. A. , Korzhevskii D. E.
Published: April 2024

The aim of this study was to assess the dynamics of distribution and localization of the gap junction protein connexin-43 (Cx43) in rat dorsal root ganglion (DRG) cells at different stages of postnatal ontogenesis to assess the morphological signs of age-related changes in intercellular interactions. The work was performed on Wistar rats at the age of 4 months and 18 months using immunohistochemical methods. Glial cells were detected using antibodies to glutamine synthetase, macrophages – using the antibodies to calcium-binding protein Iba-1. The paper describes the features of connexin-43 distribution in the spinal ganglion of young and old rats. It has been established that connexin-43-containing structures are identified mainly in satellite glial cells of young and aging animals. Sensitive neurons, as well as DRG macrophages of both groups of animals, do not show immunoreactivity. Analysis of age-related changes in intercellular contacts in rat DRG showed that plaques of connexin-43-containing protein channels that provide metabolic interaction of satellite cells in the spinal ganglia become more numerous with age. This fact may indicate the activation of the interaction between glial cells in the DRG of rats during aging.
Structural and Functional Features of Bacterial SMC Complexes
Authors: Morozova N. E. , Potysyeva A. S. , Vedyaykin A. D.
Published: April 2024

SMC complexes (Structural maintenance of chromosomes) are key participants in the spatial organization of DNA in all living organisms – in bacteria, archaea and eukaryotes. In bacteria, there are several homologues of SMC complexes that perform seemingly unrelated functions, but function through very similar, highly conserved mechanisms. In recent years, it has been established that SMC complexes are capable of forming loops from DNA (through the so-called loop extrusion), which allows them to be considered as a separate class of DNA translocases. This paper discusses bacterial SMC complexes in comparison with their homologues such as MukBEF, MksBEF, RecN, and Wadjet, as well as with eukaryotic SMC complexes. Their properties, role and functions in the key processes of the bacterial cell are discussed.
Curly Birch: Some Secrets Remain
Authors: Vetchinnikova L. V. , Titov A. F.
Published: April 2024

The article briefly recapitulates on and systematizes major results of the studies of curly (or Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti, mainly from the past two or three decades. Its main biological characteristics are described. Facts regarding curly birch resources are provided; the important role of protected areas in conserving its gene pool is emphasized. Good experience of its introduction and re-introduction is demonstrated. The origin of curly birch, the process of figured grain formation in its wood and the question of its taxonomic status are touched upon. It is pointed out that our knowledge of the nature and characteristics of curly birch as a biological object has advanced substantially over the past two or three decades, but two essential questions remain unresolved: a) origin of the curly birch and b) causes and mechanisms of figured grain formation in its wood. Answers to these questions are of much interest both theoretically and for practical causes as they would help preserve the gene pool of curly birch and contribute to augmented reproduction of its resources.
Some Methodological Approaches to the Identification of Heat Resistant Genotypes of Cultivated Plants (on the Example of Cereals)
Authors: Kruglova N. N. , Zinatullina A. E.
Published: April 2024

The problem of cultivated plants resistance to heat as the effect of high air temperatures leading to physiological drought is extremely relevant not only in the conditions of predicted climate aridization, but also when studying the effects of relatively short-term “heat waves”. Modern breeding is focused on the creation of high-yielding heat-resistant varieties of cultivated plants, especially cereals as the main world food resource. During breeding developments, it is necessary to first identify heat-resistant cereal genotypes for their insertion in the appropriate programs. The article provides a critical analysis of a number of approaches presented in the literature to identify such genotypes (modeling of the effect of the high temperature stress factor in experimental conditions in situ; the use of anthers in such conditions as the generative structures more sensitive to the effects of this stress factor in comparison with vegetative organs), which can be assessed as methodological. In addition, from the standpoint of descriptive and experimental plant embryology, the use of interrelated concepts (developed by T.B. Batygina, 2014 and earlier) is proposed as the promising methodological approach: the assessment of the anther as the complex integrated tissue system and the presence of critical stages in the development of this system.
Dynamics of Commensals Virulence: Preventive Phenotypical Mutability
Authors: Chepur S. V. , Pluzhnikov N. N. , Saiganov S. A. , Chubar O. V. , Bakulina L. S. , Litvinenko I. V.
Published: April 2024

The peculiarities of the influence of cytokines and metabolites of the systemic inflammatory reaction, stress-implementing and nutritional factors contributing to the transformation of the phenotype of the resident intestinal microflora with an increase in its virulence are described. From the perspective of gene expression, protein and phospholipids conformations, the influence of temperature as a signaling factor in increasing the virulence of the intestinal microbiome is considered. Evolutionarily formed mechanisms of expression of the maximum pathogenic phenotype of microorganisms and, thus, achieving an increase in their biomass and maximum dissemination through the microorganism compartments increases the probability of the commensals transmission to another biotope, i.e. increases the probability of their survival after the death of the host organism. To prevent bacterial translocation after the relief of critical conditions, early enteral administration of β-glucans in food mixtures, iron excretion, relief of inorganic phosphate deficiency, including by induction of alkaline phosphatase synthesis.
Abundance and Condition of Populations of Small Mammals as Carriers of Natural Focal Human Diseases in the Karelia North-East Ladoga
Authors: Ivanter E. V.
Published: April 2024

Summing up the results of the long-term studies of population ecology and dynamics of small mammals for more than half a century (1966–2018). Small mammals are involved in the formation and functioning of natural-focil of human vector-borne diseases common in the North-Eastern Ladoga region. Encephalitis and tularemia circulate intensively in the Ladoga region under conditions of intensive anthropogenic transformation of taiga ecosystems. Local landscapes belong to the subzone of the middle taiga forests. Most of the studied species of small mammals are located in the northern periphery of this area. Here representatives of the native taiga fauna of Micromammalia constantly experience powerful anthropogenic pressure, which leads to a decrease in their abundance and correlation of the species. Of the total amount of 22 species of small mammals collected here, Sorex araneus and Myodes glareolus dominate. Next, the species prevalent (according to the degree of predominant species) in the counts are Microtus agrestis, Sorex minutus and Sorex caecutiens. Other species are relatively rare and appear in smaller numbers. Myodes glareolus has main role in the feeding of ticks and, accordingly, in the circulation of infections in nature, the differentiated contribution of individual intrapopulation groups in maintaining the number of vectors and the activity of pathogens. Shrews are important for the development of the larval stages of the tick. In the research area, were recorded total index of trap catch of abundance of small animals with trap lines from 0.34 to 18.5 individuals per 100 snap traps-nights (average of 7.8 ind.) and with pitfall traps recorded from 2.7 to 25.4 individuals per 10 ditch-nights (average of 14 ind.). This indicates that the studied area has smaller amount of mammals compared to other regions in Southern Europe. Nevertheless, the studies determine a rather tense epidemic situation in the studied area. Population of small mammals of boreal ecosystem steadily affect the mass feeding of carriers of natural focal infections.