Biophysics最新文献

When studying the antimicrobial effect of various physical factors, it is useful to monitor the changes occurring with a biological object. Proteins are the main components of living cells, thus, damage to the structure of proteins and their amino acids can be a critical factor that is responsible for the death of microorganisms. UV absorption spectra and fluorescence spectra for albumin, tyrosine, and tryptophan after the action of pulsed radiation of hot plasma of the IR10 generator were studied. The fluorescence of model solutions of albumin, tyrosine, and tryptophan was compared with the fungicidal effect of an aqueous suspension of Aspergillus niger micromycetes and the bactericidal effect of E. coli depending on the dose of pulsed radiation of hot plasma spark discharge. It has been established that a decrease in fluorescence yield correlates with fungicidal effects, thus, measurements of protein and amino acid fluorescence can be used to quickly assess the possibility of damage to biological objects. The bactericidal effect is much stronger than the fungicidal effect, which indicates the predominance of mechanisms that do not affect fluorescence.

Bioactive polylactide fibers containing 6 wt % of iodine and characterized by high mechanical properties, an elastic modulus of about 3 GPa and a strength of 125 MPa, were obtained using the liquid crazing methodology. It was shown that iodine in such materials is uniformly distributed throughout the polymer volume and forms nanoparticles 5–15 nm in size. It was found that the process of destruction of iodine-containing polylactide fibers in a model medium with a phosphate-buffered saline at 37°C occurs quite quickly, in 6 weeks, the molecular mass of the polymer decreases almost an order of magnitude to 9.4 kDa, and the dispersion increases to 5.5. Under in vivo conditions, in the presence of iodine-containing fibers, the inflammatory reaction phase is suppressed and muscle tissue hypertrophy is stimulated.

The α-subunits of the Kv1.2 potassium voltage-gated channel, whose function is to regulate neuronal conductivity in the central nervous system, form heterotetramers with α-subunits of related Kv1 channels, which differ in composition and stoichiometry. To study heterotetrameric channels in vitro, concatemers have been constructed by sequentially connecting the Kv1 α-subunits. The method for constructing concatemers that allow reproducing the properties of native channels requires detailed study. In this work, concatemers (dimers) of Kv1.2 α-subunits (mKate2-Kv1.2-Kv1.2) labeled with the fluorescent protein mKate2 were constructed and their expression was carried out in mouse neuroblastoma Neuro-2a cells. It was shown that the Kv1.2 channel assembled from concatemers is almost identical in its properties, namely, intracellular distribution, ability to integrate into the plasma membrane, efficiency of interaction with a peptide blocker, as well as in its electrophysiological characteristics, to the Kv1.2 channel based on monomeric mKate2-Kv1.2 α-subunits.

The contribution of museum collections to modern scientific research has increased significantly due to the development of modern omics technologies and methods of genetic analysis. However, despite the transition to digital data storage formats, their handling and collection management are still fraught with difficulties. Existing software tools are designed to solve specific tasks and often require advanced technical skills that limits the scope of their applicability. To solve these problems, we have developed BearBase, a convenient and portable database management system that does not require advanced information technology expertise. It has both server and client components, supports offline operation, as well as synchronization with mobile devices for working in the field. Users can easily import data from formats such as MS Excel and modify the database structure as needed. The open-source software is available on GitHub. Currently, BearBase stores data on about 500 specimens of the polar bear (Ursus maritimus) from the collection of the Zoological Institute of the Russian Academy of Sciences (St. Petersburg), covering the time interval of active research and industrial development of the Arctic region from the middle of the 19th century to the present day. In addition, the system can be used to manage collections of any biological or medical samples.

The dynamics of hamsters’ motor activity was compared with the number of strong earthquakes with a magnitude ≥4.5. A positive correlation was found between the total daily motor activity calculated for the period from 6 p.m. on the previous day to 6 p.m. on the current day and the global seismic activity of the current day (r = 0.34, p = 0.02). Numerous local aftershocks do not affect the biological indicator under study. The data obtained indicate that it is not the effects of earthquakes on the geosphere that affect animals, but global seismic activity that is only a marker of the desired biotropic factor. Moreover, a long-term two-center study (Moscow and Ulyanovsk) established a positive correlation (r = 0.42, p = 0.003) between the intensity of oscillations in the counting rate from the natural isotope potassium-40 and the level of global seismicity (excluding aftershocks). Taking into account the previously identified relationship between oscillations in the counting rate from ⁴⁰K and biological parameters, this fact indicates the existence of some general influence on animal activity, radioactive decay and global seismicity.

It has been shown that the conversion of the nitrosonium (NO⁺) cation into the NO molecule in sodium nitroprusside under the action of a strong reducing agent, sodium dithionite, does not completely suppress the cytotoxic effect of sodium nitroprusside solution as a NO⁺ donor on MCF-7 tumor cell culture. The fact is that NO molecules and Fe²⁺ ions released from nitroprusside under these conditions form, together with thiol-containing ligands (thiosulfate as a degradation product of sodium dithionite and thiol groups of proteins), dinitrosyl iron complexes in which half of the nitrosyl ligands are represented in the form of cytotoxic nitrosonium cations. The amount of dinitrosyl iron complexes formed in this process is more than 3 times lower than the initial level of sodium nitroprusside and is the main reason for the weakening of the cytotoxic effect of sodium nitroprusside solution on cell culture.

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.

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%, was observed when the drugs were administered in the sequence “diethyldithiocarbamate, and then 1 h later binuclear dinitrozyl iron complexes”; whereas when the drugs were used in the reverse sequence, inhibition of tumor growth did not exceed 30%. Based on the analysis of EPR measurements of tumor tissues (on the 15th day of tumor development), it was concluded that the inhibition of tumor growth was caused by nitrosonium cations released from binuclear dinitrosyl iron-glutathione complexes during the breakdown of these complexes under the action of sodium diethyldithiocarbamate.