The problem of stretching a flexible polymer with given conditions at the ends, under the action of a fixed force, is considered. A mathematical model is constructed for different energy functions describing the elasticity of the polymer and different immobilization methods. It is shown that the dependence of stretching on the polymer length is linear. Numerical results are given. The results obtained allow to improve the analysis of experimental data on polymer stretching. The theory offers several verifiable predictions, and experimental methods are proposed to improve the accuracy of measurements.
A study was conducted to investigate the antiulcer activity of the polysaccharide from Solanum tuberosum L. in chronic and acute ulcer models proposed by Selye and Okabe. The antiulcer effect was assessed by determining and comparing the ulcer index in the treated animals and a control. The groups of treated animals that received a daily administration of polysaccharide for 7 and 3 days showed a significant decrease in the ulcer index when compared with that of the control group of animals given physiological saline. In the presence of polysaccharide, the incidence of pathological conditions (hyperemia, edema, and internal bleeding) decreased substantially regardless of the dose. This indicates that the polysaccharide may effectively prevent changes associated with the development of ulcerative colitis in the “August” line rats in the ulcer model adduced by Selye. According to Okabe, the polysaccharide dose (0.5 mg/animal) even in a single administration led to significant and in some cases almost complete healing of ulcers.
Сryoprotective properties of cholesterol/randomly methylated beta-cyclodextrin (RAMEB) inclusion complexes with respect to human spermatozoa have been investigated. The influence of different concentrations of RAMEB and cholesterol/RAMEB inclusion complexes on sperm membranes has been explored. It was shown that obvious cytotoxicity of RAMEB against spermatozoa is due to the interaction between cyclodextrins and lipid components of the membrane, in particular cholesterol extraction. Cholesterol/RAMEB inclusion complexes are significantly less cytotoxic. The dependence of cholesterol concentration in sperm membranes on the concentration of cholesterol/RAMEB inclusion complexes in the sample was established. It was demonstrated that incubation of spermatozoa with 2 mg/ml of cholesterol inclusion complexes before cryopreservation caused a statistically significant increase in survival rate (by 13.8%) and in the proportion of progressively motile spermatozoa (by 14.8%) post-thaw. X-ray diffraction revealed that the concentrations of RAMEB or cholesterol/RAMEB inclusion complexes (2, 4 and 8 mg/mL) do not affect the average size of ice crystals formed in the sample during cryopreservation in the samples. The mechanism of the cryoprotective effect of cholesterol/RAMEB inclusion complexes is proposed.
This study analyzed genetic data using DNA isolated from museum specimens of polar bears in the collection of the Zoological Institute of the Russian Academy of Sciences. The unique data obtained in this study made it possible to characterize the population structure of polar bears in the past and to lay the foundation for further research. Methods of DNA isolation used in archaeogenetics and paleogenetics were applied to historical materials. These methods provided a sufficient quantity and quality of DNA suitable for high-throughput sequencing. The analysis of genetic variants made it possible to reveal the population structure of spatial and temporal polar bear populations in the Russian Arctic regions and its changes associated with the economic activities that unfolded in the first third of the 20th century.
Products with a complex spatial organization were formed during ab initio synthesis using the large fragment of the Bst DNA polymerase. Using the analysis of AFM images of products obtained with the addition of a minimal amount of the nicking endonuclease Nt. BspD6I during this synthesis it was possible to describe the structures that formed as a result of this synthesis and suggest that their formation occurs by the mechanism of recombination-dependent replication.
The search for effective and safe radio-modulating compounds that reduce cancer cell radioresistance and/or the concomitant damage to normal tissues caused by radiation remains a significant challenge in radiation therapy. Peroxiredoxin 6, a member of the thiol-specific peroxidase family, is a promising candidate to solve this problem. However, often in studies, insufficient attention is paid to radiation parameters and there is no information about how different radiation parameters influence the radioprotective effect of exogenous peroxiredoxin 6. This article shows the peculiarities of the radioprotective effects of intravenous peroxiredoxin 6 at a concentration of 20 μg/g body weight and its mutant form Prx6-C47S (without peroxidase activity) administered shortly before X-ray or γ-irradiation with different dose rates and exposure times. Survival rates of the 10 Gy γ-irradiation 0.125 Gy/min and 7 Gy X-ray irradiation 1 Gy/min animal groups (an 8-fold difference in dose rate and exposure time) were correlated both for control and experimental animals.
A decrease in the intensity of the processes of apoptotic and necrotic death of human peripheral blood lymphocytes was found after exposure to UV light (254 nm, 1510 J/m2) and hydrogen peroxide (10–5 mol/L) in the presence of resveratrol (10–7, 10–6, 10–5 mol/L). It was revealed that the cytoprotective effect of resveratrol on lymphocytes is due to a decrease in the level of production of intracellular reactive oxygen species and calcium ions, an increase in the activity of antioxidant enzymes, that is, catalase and glutathione reductase, an increase in peroxide resistance of plasma membranes, and interaction with DNA. Possible mechanisms of action of resveratrol as a regulator of the processes of apoptotic and necrotic death of lymphocytes induced by exposure to hydrogen peroxide and UV radiation are discussed.
No differences were found in antiviral action of the solutions of binuclear dinitrosyl iron complexes with glutathione (B-DNIC-GSH) and sodium diethyldithiocarbamate (DETC) delivered sequentially to SARSCoV-2-infected Syrian hamsters in nose-only (the present study) inhalation or whole-body exposure chambers. In a whole-body exposure chamber, the animal became wet and it led only to a decrease in the level of mononuclear DNIC (M-DNIC) with thiol-containing proteins in lungs resulting in diminished EPR signal while the total Band M-DNIC pool remained unchanged. It is suggested that antiviral activity of D-DNICGSH + DETC against SARS-CoV-2 virus is due to nitrosonium cations released from B-DNIC-GSH in its decomposition induced by DETC. Without additional aerosol inhalation delivery of the solutions of DETC to animals, complex with mercaptosuccinate that is less stable than B-DNIC-GSH exerted similar antiviral effect on Syrian hamster model.
Using an experimental model of dysbiosis caused by the antibiotic gentamicin sulfate, the effect of low-intensity electromagnetic radiation of extremely high frequencies (42.2 GHz, 100 µW/cm2, pulse modulation by a meander with a frequency of 1 Hz, exposure for 30 min per day for 10 consecutive days, starting from the 4th day after induction of dysbiosis) on the fatty acid composition of the thymus, blood plasma, activity of antioxidant enzymes, the content of malondialdehyde and lactate in the blood of laboratory rats was studied. A significant decrease in the content of myristic, palmitic, stearic, palmitoleic, oleic and linoleic fatty acids in the thymus of animals was shown. The activity of antioxidant enzymes, the content of fatty acids and malonic dialdehyde in the blood did not change. The content of lactate in the blood plasma decreased. Irradiation of animals with dysbiosis normalized the fatty acid composition of the thymus and the content of lactate in plasma. The high efficiency of low-intensity extremely-high-frequency electromagnetic radiation with certain parameters in dysbiosis opens up fundamentally new possibilities for using radiation in this range for the prevention and treatment of a number of pathological conditions associated with dysbiosis.
Radiation therapy occupies one of the key places in the arsenal of cancer treatment methods. This non-invasive method has been actively used for many decades and has demonstrated high effectiveness in combating various types of malignant neoplasms. Despite significant progress in ionizing radiation delivery technologies and the introduction of targeted radiosensitizers and immunotherapy, classical radiation therapy faces limitations related to radioresistance of tumor cells. This is due to a variety of factors, such as genetic mutations, metabolic features of cancer cells, their ability to repair DNA, the presence of a tumor microenvironment, and many others. Radioresistance of tumors reduces the success of treatment, which makes it necessary to search for new approaches to improve the effectiveness of radiation therapy. This review discusses the basic principles of radiation therapy and the properties of cancer cells that affect their radiosensitivity. Both the existing methods of overcoming cancer cell radioresistance and the prospects for their further development are being considered, which can significantly improve the effectiveness of cancer treatment.
The morphological structure and functional properties of musculature in a flatworm Fasciola hepatica (Trematoda, Fasciolidae), a dangerous parasite of farm animals and humans, have been studied. The flatworm body musculature was stained histochemically with fluorescently labeled phalloidin and analyzed using fluorescence microscopy. The presence of staining was found in the longitudinal, circular, and diagonal muscle fibers of the worm’s body wall, as well as in the circular and diagonal muscle fibers surrounding the lumens of the branched intestine, as well as in the tubular muscle structures of the reproductive tract. Densely packed and intensely stained layers of muscle fibers were found in the ventral and oral suckers of the flatworm. Physiological studies conducted on muscle preparations isolated from F. hepatica, demonstrated the presence of spontaneous contractile activity of the muscles. The neuropeptide GYIRF, from the family of FMRFamide-like peptides, at concentrations of 1–10 µM, additionally stimulated the contraction of muscle preparations of F. hepatica, increasing the frequency and amplitude of muscle contractions compared with their basic activity. The information obtained will be used in further study of the mechanisms of muscle contraction in parasitic worms, whose musculature is the target of existing antiparasitic drugs.
One important direction in cancer prevention is the development of novel strategies that can be used in treatment by affecting the mechanisms of the regulatory pathways and genomic elements involved in malignant transformation. The strategy proposed in this study is to initiate cell death mechanisms in response to the depletion of the energy resources within a cancer cell due to the uncontrolled spread of mobile genetic elements throughout its genome. The calculation results obtained using a preliminary mathematical model that simulates the cellular bioenergetic balance, taking the energy consumption for retrotransposition of the mobile elements such as LINE-1 and SINE into account, show that this scenario is plausible. Intracellular resources undergo a critical redistribution when affecting the genomic defense mechanisms and the LINE-1 transcription rate. This leads to a sharp increase in energy consumption for retrotransposon transcription that causes a significant decrease in the pool of free ATP in the cell.
The aim of this study was an attempt to prevent the decrease in sperm motility of the fruit fly Drosophila melanogaster that occurs in the early period of readaptation after space flight by adding phospholipids with polyunsaturated fatty acids in the tail groups (essential phospholipids) to the nutrient medium. The study was carried out as part of space flights on board the Russian segment of the ISS during the periods of September 15, 2023–September 27, 2023 (ISS-69) and March 23, 2024–April 6, 2024 (ISS-70). The content of cytoskeletal proteins in the testes was determined by Western blotting and sperm motility by video recording and subsequent analysis. The results of the study show that modification of the nutrient medium by adding essential phospholipids leads to a decrease in cholesterol content and an increase in actin content, which prevents a decrease in tubulin content and a decrease in the speed of movement of fruit fly sperm in the early period of readaptation (up to 16 hours) after space flight. The data we obtained, on the one hand, demonstrate a possible mechanism for triggering mechanotransduction, and on the other, allow us to propose essential phospholipids as one of the means of protection against negative changes associated with changes in the gravity field acting on the cell.
The objective of the present research was to study the action of dinitrosyl iron complexes (DNIC) with a ligand based on N-acetyl-L-cysteine upon long-term inhalation exposure of rats to this substance. It has been shown that as a result, NO stabilized forms pass efficiently through the alveolal membrane into the lung tissue leading to the accumulation of dinitrosyl iron complexes with protein ligands and to an increase in the total NO level in the lungs and other organs thereby inducing a significant and long-lasting hypotensive effect.
The problem of changes in myoneural transmission in the presence of an intercalating agent, ethidium bromide, which has a known inhibitory effect on neuromuscular transmission, has been investigated, but the nature of such an effect remains unclear. To solve the question of the possible participation in this process of known modulators of synaptic transmission, that is, purines (ATP and adenosine), we evaluated their effects in the presence of this agent. After holding a frog neuromuscular preparation in a perfusing solution containing ethidium bromide, the amplitude of postsynaptic responses and muscle contraction forces decreased. Under these conditions, both purines additionally exerted their usual suppressive effect on both the amplitude of postsynaptic responses and the strength of skeletal muscle contraction. Thus, the inhibitory effect of ethidium bromide on neuromuscular transmission is not associated with an increase in the inhibitory effect of endogenous purines caused by the quantum release of the neurotransmitter.
A study of the cytotoxic activities of two polyacrylic acid-based compounds containing gold (aurumacryl) and silver (argacryl) against a panel of human tumor cell cultures (769-P, Caki-2, SK-RC-1 renal carcinoma lines, BT-474 breast carcinoma, and NCI-H211 small cell lung carcinoma) was carried out in vitro. The results we obtained were analyzed in comparison with the data established earlier for other cell cultures (MCF-7 breast carcinoma, A-549 lung carcinoma, HCT116 colon carcinoma, and Mel Me melanoma). The IC50 cytotoxic index of drugs for the nine tested tumor cell lines ranged from 0.8 to 5.2 μg/mL for aurumacryl and from 0.2 to 14.4 μg/mL for argacryl (in terms of gold and silver content, respectively), depending on the type of tumor. Significant differences were found in the spectra of the lethal effects of aurumacryl and argacryl against tumor cells of various types.
The chickpea (Cicer arientinum) is an important crop grown in the Middle East, Central Asia, Turkey, India, and southern Russia and is used in a wide variety of traditional dishes. The decrease in genetic diversity during domestication, as well as its greater sensitivity to abiotic and biotic stresses, provides the idea of using landraces in breeding programs to improve the crop. The new IIIVmrMLM method for genome-wide association searching allowed us to identify new variants in the genetic data of the chickpea collection that were located within important genes and to identify landraces best suited to the climate of two experimental stations.
Cryopreservation of biological material is an important task in many areas of biology and medicine especially for assisted reproductive technologies. Cryoprotective media including cell-penetrating and non-penetrating components are used for effective cryopreservation of cells. Usually glycerin in various concentrations acts as a penetrating component. However, elucidating the mechanisms of the cryoprotective action of these compounds as well as increasing the proportion of surviving cells after cryopreservation remain urgent objective of cryobiology. The work examines the mechanism of glycerol transfer through sperm membranes with the participation of aquaporins using the method of mathematical modeling. The presented model describes dynamics of changes in sperm volume depending on the concentration of glycerol and sucrose in the cryoprotective medium. As a result of the analysis the characteristic time for establishing equilibrium between the studied cryoprotective medium and cells was calculated and amounts to t = 80 s in the presence of glycerol 12% vol. The concentration of sucrose (0.16 M) at which the cell returns to its original volume after incubation in a cryoprotective medium was determined. It has been shown that human sperm can contain 6750 AQP7 with a permeability PAQP7 = 0.00366 µm3/s. The experiments performed showed an increase in the sperm motility index when correcting the concentration of sucrose in the solution according to the modeling results.
The RPS12 gene in the mitochondrial genome encodes an important protein from the small ribosomal subunit. The transcript of this gene can undergo RNA editing in a number of organisms, for instance it is edited actively in all tripanosomatida. In this study, a comparison between the sequences of edited mRNA and tertiary structures of the proteins when mRNA were translated from some of the members of Tripanosomatidae family showed that tertiary structures of the RPS12 gene remained unchanged in all species while only two short conserved regions were found in the primary structure of the gene. Using computer modeling it was demonstrated that these regions encode amino acids that are turned in the decoding center of the ribosome. The nature of editing patterns demonstrates that evolutionary conservation of these regions is independent of the editing process; moreover, an evolutionary tendency to reduction of editing process in a number of sites was seen within the conserved sites of the RPS12 gene.
The combined use of two compounds, the binuclear form of dinitrozyl iron complexes with glutathione (100 µM/kg, subcutaneously) and sodium diethyldithiocarbamate (500 µM/kg, intraperitoneally), administered 8 times, caused complete inhibition of the development of a solid tumor in mice for 2 weeks after transplantation (Lewis lung carcinoma). However, when the antitumor effect was assessed on the 20th day after the end of drug administration, the maximum activity, inhibition of tumor growth by 60
