Alzheimer’s disease (AD) is the most common neurodegenerative disorder and is a cause of dementia that is linked to atrophic changes in the brain. There are two forms of AD: familial earlyonset form of AD (FAD, which accounts for ~5% of all cases) and sporadic late-onset AD (SAD, which accounts for ~95% of all cases). Identification of genetic determinants of FAD and proof of the neurotoxic effects of amyloid-beta peptide (Aβ) as a central event in the cascade of pathological processes significantly expanded understanding of the molecular and genetic mechanisms of the disease. However, the question of whether the accumulation of Aβ triggering factor for the most common SAD remain poorly understood. It is assumed that Aβ overproduction apparently becomes the secondary event of pathological processes of AD: synaptic failure, hyperphosphorylation of tau protein, neuroinflammation, neuronal loss and cognitive decline. As one of the risk factors for development of AD is mitochondrial dysfunction, a consequence of which becomes a decrease of ATP synthesis and oxidative stress. However, the specific molecular and genetic mechanisms of AD remain unclear. A major problem in AD research is the lack of an animal model that accurately replicates the human disease. This shortage makes it difficult to study the underlying mechanisms and to explore additional risk factors and therapeutic approaches to AD.

Two model systems — “replicative aging” and “chronological aging” (CA), used for gerontological research on the yeast Saccharomyces cerevisiae are compared. In the first case the number of daughter cells generated by an individual mother cell before cell propagation irreversibly stops is analyzed. This makes the model very similar to the well-known Hayflick model. In case of CA the survival of yeast cell population in the stationary phase of growth is studied. It is noted that the second model is pretty similar to the “stationary phase aging” model used in the author’s laboratory for cytogerontological studies on animal and human cells. It is considered that the conception of cell proliferation restriction as the main reason of age-related accumulation in the cells of multicellular organisms of macromolecular defects (mainly — DNA damage) leading to deterioration of tissue and organ functioning and, as a result, to the increase of death probability allows to explain how the aging process proceeds in almost any living organisms. Apparently, in all cases the process is initiated by appearance of slow propagating (or not propagating at all) cells which leads to the stopping “dilution”, with the help of new cells, of macromolecular defects accumulating at the level of whole cell population. It is concluded that data obtained in testing on the yeast CA model of various factors for their geropromoter or geroprotector activity can be with high reliability used for understanding mechanisms of human aging and longevity.

Development and functional characterization of novel high-affinity protein compounds that can selectively kill human cancer cells, is an important task of modern biomedical research. In this work the cytotoxicity of recombinant phototoxic protein DARPin-miniSOG on HER2- positive breast adenocarcinoma human cells has been studied. It was determined that targeted phototoxin DARPin-miniSOG specifically interacts with HER2 receptor and causes necrotic death of HER2-positive cells induced by illumination. Treatment of the cells with DARPinminiSOG in the presence of ascorbic acid eliminates the light-induced cytotoxic action of the protein that confirmed the mechanism of action of the protein through oxidative stress.

Salicylhydroxamic acid (SHAM), an inhibitor of the alternative oxidase in plant mitochondria, accelerated the NADH-oxidase activity in suspensions of mitochondria and chloroplasts, obtained by their isolation from the roots or leaves of pea, respectively. The reaction was suppressed by washing mitochondria and chloroplasts. It also proceeded in supernatants where the organelles were removed by centrifugation. The reaction was sensitive to CN– and propyl gallate, an antioxidant. In addition to SHAM, NADH oxidation was stimulated by 2,4-dichlorophenol or phenol, but not by salicylic acid. The acceleration of NADH oxidation by the phenolic compounds occurred in the presence of commercial horseradish peroxidase. It is due to the involvement of these compounds in the NADH-dependent peroxidase reaction. 2,4-Dichlorophenol and SHAM enhanced significantly destruction of nuclei in guard cells of the epidermis from pea leaves induced by generation of reactive oxygen species under oxidation of exogenous NADH by means of the apoplastic peroxidase.

BALB/с mice were immunized with recombinant Ebola virus glycoprotein. Following selection, screening and cloning of murine hybridomas we obtained 5 genetically stable clones of monoclonal antibodies GPE118 (IgG), GPE274 (IgM), GPE325 (IgM), GPE463 (IgM), and GPE534 (IgG). These antibodies were isolated and purified from ascitic fluid of BALB/с mice using Protein G affinity chromatography (IgG) and euglobulin precipitation method (IgM). For the selection of at least 3 candidate antibodies to be tested in biological assays as components of an antibody cocktail for the prophylaxis and treatment of hemorrhagic fever, we carried out an immunochemical analysis of epitope specificity of isolated antibodies. Based on immunoblotting and sandwich ELISA data, it became evident that the epitope recognized by GPE 534 is different from GPE 118 and GPE 325 epitopes. The latter two antibodies also have different epitope specificity. It is evidenced from immunoblotting data as well as from binding data of these antibodies with intact and oxidized (partly deglycosylated) recombinant glycoprotein. For the studies of biological activity and the development of recombinant counterparts, we isolated 3 candidate high-affinity monoclonal antibodies GPE 534, GPE 118, and GPE 325.

We discuss the question of constructing three-dimensional models of DNA complexed with proteins on the basis of computer modeling and indirect methods for studying the structure of macromolecules. We consider methods of interpreting the experimental data obtained by indirect methods for studying the three-dimensional structure of biomolecules. We discuss some aspects of the integration of such data in to the process of molecular models building (based on the geometric characteristics of DNA). We propose an algorithm for the estimation of protein-DNA complexes structure on the basis of information about the local DNA flexibility and experimental data obtained by Forster resonance energy transfer (FRET) and hydroxyl footprinting methods. Finally, we use this method for prediction of the hypothetical configuration of DNA in nucleosome bound with histone H1.

One of the most promising and reliable methods for analysis of the structure of macromolecules is cryo-electron transmission microscopy with subsequent three-dimensional reconstruction. In this study, this method was used to study transcription by RNA polymerase, stalled at the position 42 bp into a nucleosome. We obtained the projection images and solved the three-dimensional structure of the complex EC-42 with the 2.5 nm resolution. It allowed us to confirm the conformational integrity of the nucleosome, during the passage of RNA polymerase.

Immunochromatography test systems were developed for molecular diagnostics of the potato virus Y and PLRV infection. To increase a low yield of PLRV and raise antibodies against the PLRV antigen, chimerical virus was constructed comprising the PLRV coat protein and recombinant RNA of a tobamovirus, in which capsid protein gene was replaced by the PLRV coat protein gene. Binary vector containing the DNA copy of the recombinant RNA was infectious, and yield of the chimerical virus increased up to 800 times in comparison with the WT PLRV. On the basis of experience in the development of the diagnostics of viral and viroid infections, a rational tactics is proposed for the mass laboratory and field diagnosis of viral infections on the molecular level.

Formation of viral ribonucleoprotein particles during incubation of the Alternanthera mosaic virus 5′-end transcripts with Potato virus X (members of the Potexvirus genus) coat protein was studied. It was shown that the capping of Alternanthera mosaic virus transcripts affects the efficiency of their interaction with a coat protein. At the same time the removal of the cap structure from previously capped Alternanthera mosaic virus transcripts did not prevent viral ribonucleoproteins assembly. The removal of the first 100 nucleotides (the likely site for assembly initiation) had no effect on the formation of viral ribonucleoproteins. The additional evidences that the potexvirus ribonucleoproteins assembly does not depend on the RNA nucleotide sequence were obtained.

In recent years, it has been shown that LOV (light, oxygen, voltage) and BLUF (Blue Light sensing Using FAD) photosensory proteins are functioning as photoreceptors of light-regulated processes not only in eukaryotes but also in numerous prokaryotes. In bacterial photoreceptors, LOV and BLUF domains with attached flavin chromophores are often associated with different effector domains, which possess enzymatic and other functions, constituting modular lightswitchable systems. Nowadays, progress has been achieved in uncovering the photoactivation mechanisms of such systems, which based on the chromophore photoreaction-induced changes  in the photosensory domain structures and subsequent signal transduction to the effector domains. Knowledge of signal transduction principles in LOV and BLUF photosensors is important for designing on their basis photo-switchable enzymes and transcriptional systems, which have been applied in optogenetics — a new field in cell biology and biotechnology. The structural aspects of signal transduction by light-activated LOV and BLUF photoreceptors and their regulatory functions in bacteria as well as on some recent advances in using LOV and BLUF photosensors as actuators in optogenetic systems for regulation of cellular processes are discussed.

It was demonstrated by means of probe microfluorimetry of single cells that tuftsin in concentrations 0.1 and 1.0 ug/ml (that increase murine peritoneal macrophages phagocytic activity) changed intracellular pH (pHi) biphasicaly over time. At the beginning there was a decrease of pHi reaching the ultimate expression after 5 min of incubation. After that pHi value increased, reaching maximum 30 min later. The observed parameter (pHi) did not change up to 55 min. It was found that after administration of the Na+/H+ exchange blocker ethylisopropylamiloride into the cells incubation medium during tuftsin treatment there was no increase of intracellular pH. This finding can be the evidence that the observed increase of pHi during tuftsin treatment through the second phase of cellular response connected with the system of Na+/H+ exchange.

It was shown that extracellular proteinases produced by micromycetes A. ochraceus L-1 and A. ustus 1 differ by the values of activity at various pH values and the intensity of its effect on fibrillar proteins. It was revealed that the proteinase of A. ochraceus L-1 demonstrated maximum activity during the growth of the producer on nitrate-free growth medium, at pH 8.0, and proteinase of A. ustus 1 showed maximum activity during the growth of the micromycete on a medium containing sodium nitrate, at pH of 6.0. Values of specific fibrinolytic and collagenolytic activities of A. ochraceus L-1 were in 2.2 and 1.6 times greater than those activities of A. ustus 1, but A. ustus 1 showed low values of total proteolytic (caseinolytic) activity and had a high ratio of fibrinolytic activity to total proteolytic (caseinolytic) activity (6.92), making it a promising producer of proteinases which hydrolyze fibrin and collagen.