Том 63, № 1 (2018)

The mechanics of the conformational motions of macromolecules due to rotations around the valence bonds in a viscous medium have been considered. The variational principles for the energy-dissipation rate during conformational motions in a viscous medium and the rate of the potential energy decrease of a macromolecule during conformational relaxation have been analyzed. The seeming contradiction between this principle and the principle of the minimum energy-dissipation rate is resolved. It is shown that the energy-dissipation rate must be optimal and minimal in order to simultaneously satisfy the conservation laws and fulfill the deterministic nature of classical trajectories. The generalization and analysis of the influence of thermal fluctuations and external forces on the variational principles for the conformational relaxation of macromolecules is carried out. A visual graphical geometric depiction has been developed using hyperspheres in the space of the velocities of chain nodes to describe conformational movements along many degrees of freedom in a viscous medium. The equipartition of the energy-dissipation rates (and the rates of potential energy decrease) among the conformational degrees of freedom is discussed.

It has been shown that Dulbecco’s incubation medium prepared with electrochemically reduced water compensates for oxidative stress induced by hydrogen peroxide addition (H₂O₂, 0.2 mM) to the incubation medium. The incubation medium modified in this way does not affect the H₂O₂ induced apoptosis in an early mouse embryo. The embryonic cell in the experimental model of apoptosis shows the presence of characteristic morphological changes and decreased cell volume. These apoptosis-related changes were detected using laser-scanning microtomography.

Interactions of 7-aminoactinomycin D (a fluorescent analogue of actinomycin D, an anticancer antibiotic) and two structural forms of the model guanine-rich telomeric oligonucleotide d[AGGG(TTAGGG)₃] have been studied. We have shown that 7-aminoactinomycin D induces fluorescence in two G-quadruplex structures formed with the presence of potassium or sodium ions. The enthalpy of the interaction between the phenoxasone chromophore of the antibiotic and the telomeric oligonucleotide as determined by analysis of excitation spectra is 5.5 kcal/mol. This value differs little from those obtained for complexes with guanine, adenine, or thymine aggregates (6–7 kcal/mol). In the oligonucleotide, the antibiotic is located within dynamic cavities. Therefore, 7-aminoactinomycin D is not released from telomeric structures to the aqueous phase spontaneously or even by photoexcitation, but it is easily released from the surface of aggregates of the respective nucleobases. The entropy term of the interaction energy calculated as a difference between the total energy determined from the binding constant and the enthalpy determined from excitation spectra constitutes approximately 30% for the telomeric oligonucleotide and is virtually null in interactions with nucleobase aggregates.

Gene regulatory networks control the complex programs that drive development. Deciphering the connections between transcription factors (TFs) and target genes is challenging, in part because TFs bind to thousands of places in the genome but control expression through a subset of these binding events. We hypothesize that we can combine natural variation of expression levels and predictions of TF binding sites to identify TF targets. We gather RNA-seq data from 71 genetically distinct F1 Drosophila melanogaster embryos and calculate the correlations between TF and potential target genes' expression levels, which we call “regulatory strength.” To separate direct and indirect TF targets, we hypothesize that direct TF targets will have a preponderance of binding sites in their upstream regions. Using 14 TFs active during embryogenesis, we find that 12 TFs showed a significant correlation between their binding strength and regulatory strength on downstream targets, and 10 TFs showed a significant correlation between the number of binding sites and the regulatory effect on target genes. The general roles, e.g. bicoid’s role as an activator, and the particular interactions we observed between our TFs, e.g. twist’s role as a repressor of sloppy paired and odd paired, generally coincide with the literature.

Electron spin resonance (ESR) and atomic force microscopy (AFM) were used to study liposomes that were prepared from soybean phosphatidylcholine (PC); they incorporated plant antioxidants (ginger, allspice, and black-pepper extracts; clove oil; etc.) that were encapsulated in biopolymers (sodium caseinate or sodium caseinate–maltodextrin covalent conjugates). Plant antioxidants were shown to cause a 15–25% decrease in the microviscosity of deep-lying regions of the liposome lipid bilayer by ESR with a 16-doxylstearic acid spin probe. A ginger extract exerted the greatest effect (24%). Sodium caseinate and its covalent conjugates with maltodextrins (dextrose equivalents (DEs) 2 and 10) increased the microviscosity by 30–35% as compared with free and antioxidant-incorporating liposomes. AFM showed that antioxidants increased the cross-sectional area and volume of liposomes and that the polymers made liposomes denser and their structure more compact.

The aim of this study was to examine the effects of sucrose, dextran, polyethylene glycol, glycerol, and mannitol, which possess cryoprotective properties to various degrees, on the mechanical stability and the geometric parameters of human erythrocytes. All substances, except mannitol, contributed to a decrease in hemolysis, which was caused by the movement of small beads. Glycerol and polyethylene glycol, which provide the highest level of protection of erythrocytes during cryopreservation, also showed the maximum efficiency under mechanical stress. Changes in cell resistance may be associated with the transformation of their geometric parameters. According to the cytometry data, 5% solutions of all the substances, except mannitol, caused similar changes in the geometric parameters of the cell. The relationship between changes in the mechanical stability and the geometric parameters of erythrocytes under the influence of cryoprotective agents may be caused by the modification of the membrane−cytoskeleton protein complex, which controls the mechanoelastic properties and morphology of erythrocytes.

A study of the regenerative potential of bone marrow cells of donor mice that express the enhanced green fluorescent protein was conducted in mice irradiated at a dose of 7 Gy. Expression of this protein allowed us to carry out monitoring of the presence of donor cells in recipient blood over the entire lifespan of the recipient. The lifespan of young recipients increased by 93% after transplantation; for old recipients it increased by 15%. Total acceptance of the bone marrow, spleen, thymus, and blood of the recipient with donor bone marrow cells was demonstrated over the entire life of the recipient. Only the donor colonies were detected with the studied irradiation dose and number of transplanted cells (11.7 ± 0.4) · 10⁶ on the spleen surface. The percentage of bone marrow and spleen cells that expressed the CD117 and CD34 stem cell markers in the recipient mice was above the control level for a long period of time after the irradiation. More than half of the cells with CD117, CD34, CD90.2, and CD45R/B220 phenotypes in the studied organs were donor cells. Further detailed study of the peculiarities of the engraftment of bone marrow cells, both without preliminary treatment of recipients and after the effects of extreme factors, will allow improvement of the methods of cell therapy.

A comparative evaluation of the level of extracellular peroxidase activity and light-emission intensity of the mycelium of the luminescent basidiomycete Neonothopanus nambi in the presence of β-glucosidase was performed. The enzyme activity damages the hyphae of the fungus leading to osmotic imbalance, partial degradation of the mycelium, and release of extracellular peroxidases into the incubation medium. The presence of β-glucosidase reduces the time necessary to reach the maximum luminescence. Putative biochemical mechanisms that underlie the stimulation of reactive oxygen species formation (first and foremost, of hydrogen peroxide) in the N. nambi mycelium in the presence of β-glucosidase are proposed.

The effects of exposure to low-intensity continuous radiation in the red and near-infrared regions of the spectrum, as well as to infrared pulsed radiation, on the early development of zebrafish (Danio rerio) were studied. It was found that the use of continuous radiation at the red and infrared wavelengths (633 nm, 930 nm, dose 24 mJ/m²) leads to accelerated development of the embryo. In contrast, exposure to low-intensity single pulsed infrared radiation (864 nm) in the entire range of the doses studied (2.4–2400 mJ/cm2) negatively affected the early development of zebrafish, resulting in a significant dose-dependent delay in the hatching time of embryos and a reduction in the body length of larvae.

A skin blood flow was studied by laser doppler flowmetry. Fourteen male BALB/c mice were used. The skin blood flow was registered in the left hind paw. To measure the skin microhemodynamics, we proposed a protocol of animal immobilization with two types of anesthesia, injection with zoletil and inhalation with nitrous oxide. The borders of low-frequency intervals of oscillations of the microhemodynamics in mice have been determined; they coincided with those for humans and rats that were determined earlier.

The effect on reduction/oxidation (redox) reactions was studied for the first time for pulsed current exposure using a Darsonval’ Korona physiotherapeutic device. The reactions were studied in Fe²⁺, Fe³⁺, KI, tryptophan, tyrosine, and phenylalanine model solutions. Treatment with the device induced redox reactions and quenched the fluorescence of aromatic amino acids. The highest yields of redox reactions and the greatest fluorescence quenching were observed within the first 0.5–2 min from the start of treatment. In the case of one-electron transfer (a Fe²⁺/Fe³⁺ system), the yields of oxidation and reduction reactions were approximately proportional. In the case of two-electron transfer (a I^–/I₃^- system), only reduction was observed, while oxidation was suppressed. The effect was presumably associated with the duration of the pulsed current half-wave. The results implicate redox processes triggered by microdischarges on the electrode surface in the therapeutic effect of D’Arsonval treatment.

New nonlinear regression models were developed to predict climatic factor dependences of the periods of time from sowing to seedling emergence and from seedling emergence to flowering in soybean. The developed regression models are more accurate than earlier models, but are more complex in structure.