Ecological condition and invasiveness of Fraxinus pennsylvanica in different ecotopes of the arid Caspian region.

The study investigated ash development in an arid region, focusing on its invasive spread mechanisms at organismic and ecosystem levels under varying moisture conditions. Conducted in the Northern Caspian region's Volga-Urals interfluve, it examined the effects of arid climate, soil salinity, and limited moisture on plant communities. The features of ash functioning at the organismal and ecosystem levels with permanent and partial deficiency of productive moisture in the soil, as well as with its optimal availability, were investigated. It is shown that on automorphic soil types, ash cultures, subject to appropriate forestry technologies, can exist for many decades even during periodic soil droughts due to premature harmless dumping of leaf mass. In hydromorphic floodplain conditions, ash is not only well preserved in cultures, but also effectively introduced into meadow and forest ecosystems by lowering the relief. Trees in a new place, especially in meadows, begin to bear fruit after 6-10 years and spread the seeds to other territories. Such a nomadic strategy of stepwise dispersed multiple dispersal of ash contributes to the rapid formation of its secondary invasive areas and eliminates the possibility of effective control against it. Therefore, the use of ash in industrial plantings in floodplains is highly inadvisible.

The effect of lactoferin on the free radical and cytokine status of cornea in the experimental thermal burn.

The free radical and cytokine statuses of the cornea during its thermal burn and the possibility of its correction by lactoferrin have been studied in Soviet Chinchilla rabbits. The development of a corneal thermal burn was accompanied by the development of oxidative stress (increased levels of TBA-reactive substances and carbonyl derivatives of proteins, decreased activity of SOD and GPx enzymes) and a pronounced inflammatory reaction with increased levels of TNF-1α, IL-10, TGF-1ß. The use of lactoferrin had a pronounced therapeutic effect, which was manifested by accelerated healing, prevention of the development of complications (corneal perforations), a decrease in the severity of oxidative stress, an increase in the concentrations of TNF-1α (in the early stages), IL-10 (in the later stages), TGF-1ß (throughout the experiment). At the same time, by the end of regeneration more severe corneal opacification was recognized compared to the control group. This may be associated with an increased level of anti-inflammatory cytokines, especially TGF-1ß.

A dataset of microstructure features and physicochemical properties of soils of the solonetzic complex in 2022 (Caspian lowland).

The fact of global climate change is generally recognized by the world scientific community. However, the spatial distribution of climatic parameters is very heterogeneous. In this regard, studies of the local response of individual territories to global climate change are of particular importance. The nature of dry-steppe and semi-desert regions is most vulnerable to climatic fluctuations. The soil cover of the Caspian lowland is characterized by the predominance of saline and saline soils, which react quickly to even small climate changes. At the same time, long-term climate changes can affect such stable soil characteristics as granulometric composition and microstructure. This article presents data collected on the territory near the Dzhanybek Research Station of the Institute of Forest Science RAS. The studied object is represented by microcatena of light chestnut soils with varying degrees of severity of the saline process which is located in the saline complex between the I and II belts of the Chapaevsk-Vladimirovka State Forest Wind Belt. The height range between the studied pits is 4 cm. The dataset includes data on soil grain size distribution, organic carbon content, the composition of absorbed bases, the salt composition of soil-water extract and microphotographs of the state of the light chestnut soils in 2022. This year is a reference point for further long-term monitoring of changes in soil properties and assessment of their dependence on climate change.

Immune response to Vi-antigen of Salmonella typhi is dependent on introduction of positive charge and shape of charged group into polysaccharide.

A model of a controlled conversion of polysaccharide Vi-antigen of S. typhi into zwitterionic antigen is proposed. The immunological properties of modifications of this antigen conjugated to a protein support were studied.

[Aptamers in the Treatment of Bacterial Infections: Problems and Prospects].

Aptamers are short single-stranded oligonucleotides which are selected via targeted chemical evolution in vitro to bind a molecular target of interest. The aptamer selection technology is designated as SELEX (Systematic evolution of ligands by exponential enrichment). SELEX enables isolation of oligonucleotide aptamers binding a wide range of targets of interest with little respect for their nature and molecular weight. A number of applications of aptamer selection were developed ranging from biosensor technologies to antitumor drug discovery. First aptamer-based pharmaceutical (Macugen) was approved by FDA for clinical use in 2004, and since then more than ten aptamer-based drugs undergo various phases of clinical trials. From the medicinal chemist's point of view, aptamers represent a new class of molecules suitable for the development of new therapeutics. Due to the stability, relative synthesis simplicity, and development of advanced strategies of target specific molecular selection, aptamers attract increased attention of drug discovery community. Difficulties of the development of next-generation antibiotics basing on the conventional basis of combinatorial chemistry and high-throughput screening have also amplified the interest to aptamer-based therapeutic candidates. The present article reviews the investigations focused on the development of antibacterial aptamers and discusses the potential and current limitations of the use of this type of therapeutic molecules.

[Development of Specific Therapy to Category A Toxic Infections].

Category A select agents continue to be major threat to human population both as naturally occurring diseases and as potential weapon of bioterrorists. Anthrax and botulism are probably the most threatening agents as both have virtually uncontrolled natural reservoirs from which they can be isolated and propagated. Available specific antitoxin therapy of both diseases is outdated; its efficiency is questionable as well as safety of reactogenic or human-derived components used in treatment. Highly sensitive toxin detection techniques are still not as widespread as it needed for timely alerting medical services. There is urgent need of pre-exposure prophylaxis and postexposure specific antitoxin therapy for anthrax and botulism. Analysis of modern studies in the field suggests oligoclonal antibodies acting against receptor-binding toxin subunits and nucleic acid aptamers as allosteric inhibitors of metlloproteolytic toxin components as the most promising candidates for development of efficient antitoxin therapy.

[CONTEMPORARY CONCEPTION OF IMMUNE RESPONSE ACTIVATION MECHA- NISM BY CONJUGATED POLYSACCHARIDE VACCINES].

Vaccination remains the most effective method of control of spread of a whole range of infections of both viral and bacterial nature. Many bacterial pathogens (Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae) carry polysaccharide capsule on the surface, that is one of the elements of protection from host organism immune system. At the same time, vaccination with bacteria exopolysaccharides (EPS) ensures infection neutralization. Effectiveness of such vaccine prophylaxis is limited by age of the vaccinated, intensity and duration of the immunity, development of secondary immune response. EPS conjugation with protein antigens was known for a long time to ensure activation of T-cell immunity against EPS and formation of secondary immune response. However, detailed studies of mechanism of immunity modulation by a protein partner as part of a glycoconjugate has not been carried out. T-lymphocyte activation was traditionally thought to occur exclusively due to peptide presentation, that are products of processing of protein component of the conjugate. Recently, information, accumulated in the field of natural carbohydrate, glycolipid and glycoprotein antigen presentation to T-cells, has generated interest in studying mechanisms of cell immunity activation by conjugated vaccines. Progress in this field, as well as development of novel chemical and biochemical, including combinative technologies of synthesis and study of these molecules, opens new opportunities for detailed understanding of mechanism of action for conjugated vaccines and creation of glycoconjugates with increased effectiveness of protective action.

[Antibiotic-dependent selection of the E. coli clones with increased chaperone activity for highly-efficient production of the full-length soluble New Delhi metallo-beta-lactamase].

The spread of the New Delhi metallo-beta-lactamase (NDM-1), a plasmid-borne enzyme conferring bacterial resistance to any known beta-lactam antibiotics, represents the global health threat. There is an urgent need to develop the efficient NDM-1 inhibitors of various mode of action thereby necessitating structural studies of the enzyme as well as analysis of the secretion pathway and localization of the protein. The recombinant full-length NDM-1 is produced in E. coli in the inactive form and is mostly accumulated in the inclusion bodies. The secreted recombinant NDM-1 forms are several N-terminally truncated species. The robust expression system capable of high-level production of the full-length NDM-1 and derivatives thereof is required to obtain NDM-1 in the quantities necessary for drug discovery, diagnostics, and research purposes. Therefore, we developed a new system that utilizes antibiotic pressure to select E. coli producing increased quantity of soluble NDM-1 and showed that an increase in the NDM-1 solubility occurs in the bacterial clones producing increased amounts in the chaperones.

Role of Structure-Based Changes due to Somatic Mutation in Highly Homologous DNA-Binding and DNA-Hydrolyzing Autoantibodies Exemplified by A23P Substitution in the VH Domain.

Anti-DNA autoantibodies are responsible for tissue injury in lupus. A subset of DNA-specific antibodies capable of DNA cleavage can be even more harmful after entering the living cells by destroying nuclear DNA. Origins of anti-DNA autoantibodies are not fully understood, and the mechanism of induction of DNA-cleaving activity remains speculative. The autoantibody BV04-01 derived from lupus-prone mouse is the only DNA-hydrolyzing immunoglobulin with known 3D structure. Identification and analysis of antibodies homologous to BV04-01 may help to understand molecular bases and origins of DNA-cleaving activity of autoantibodies. BLAST search identified murine anti-DNA autoantibody MRL-4 with sequences of variable region genes highly homologous to those of autoantibody BV04-01. Despite significant homology to BV04-01, not only MRL-4 had no DNA-cleaving activity, but also reversion of its unusual P23 mutation to the germline alanine resulted in a dramatic loss of affinity to DNA. Contrary to this effect, transfer of the P23 mutation to the BV04-01 has resulted in a significant drop in DNA binding and almost complete loss of catalytic activity. In the present paper we analyzed the properties of two homologous autoantibodies and mutants thereof and discussed the implications of unusual somatic mutations for the development of autoantibodies with DNA-binding and DNA-hydrolyzing activity.

[Prospects for application of aptamers in diagnostics of bacterial infections].

Nucleic acid-based aptamers are widely accepted as promising tools for development of a plethora of diagnostic and therapeutic preparations, as well as means ofenvironmental monitoring. Aptamers can be regarded as fully synthetic analogs of antibodies. At the same time, certain properties ofaptamers render them superior to antibodies in terms of development of new diagnostic and monitoring systems that combine high sensitivity and specificity with high reproducibility and inexpensive manufacturing. In particular, the aptamers tailored to bind biomolecules and live cells can be employed in solving the problem of combining short analysis time with high sensitivity and specificity in detection of pathogenic bacteria. The present review summarizes the current state of the techniques developed for aptamer-based detection of bacteria and their components and discusses the potential of their practical application.

[Characteristics of the immune response to the lethal toxin of Bacillus anthracis].

We and other authors have recently shown that the pattern of the immune response to components of anthrax, the Bacillus anthracis lethal toxin, is complex. In addition to neutralizing antibodies, the antitoxin antibody pool contains antibodies enhancing the toxin lethal action. We mapped the epitopes in the protective antigen that are responsible for the induction of both antibody types. In this study, we obtained new data on the cytotoxicity of the B. anthracis lethal toxin toward the J774 A.1 cell line in the presence of monoclonal antibodies to various domains of the protective antigen and the lethal factor. The role of the Fc fragment of immunoglobulins in enhancing the lethal toxin action was shown. These results may serve as a basis for the development of a new generation vaccine for anthrax.

Visual cycle and its metabolic support in gecko photoreceptors.

Photoreceptors of nocturnal geckos are transmuted cones that acquired rod morphological and physiological properties but retained cone-type phototransduction proteins. We have used microspectrophotometry and microfluorometry of solitary isolated green-sensitive photoreceptors of Tokay gecko to study the initial stages of the visual cycle within these cells. These stages are the photolysis of the visual pigment, the reduction of all-trans retinal to all-trans retinol, and the clearance of all-trans retinol from the outer segment (OS) into the interphotoreceptor space. We show that the rates of decay of metaproducts (all-trans retinal release) and retinal-to-retinol reduction are intermediate between those of typical rods and cones. Clearance of retinol from the OS proceeds at a rate that is typical of rods and is greatly accelerated by exposure to interphotoreceptor retinoid-binding protein, IRBP. The rate of retinal release from metaproducts is independent of the position within the OS, while its conversion to retinol is strongly spatially non-uniform, being the fastest at the OS base and slowest at the tip. This spatial gradient of retinol production is abolished by dialysis of saponin-permeabilized OSs with exogenous NADPH or substrates for its production by the hexose monophosphate pathway (NADP+glucose-6-phosphate or 6-phosphogluconate, glucose-6-phosphate alone). Following dialysis by these agents, retinol production is accelerated by several-fold compared to the fastest rates observed in intact cells in standard Ringer solution. We propose that the speed of retinol production is set by the availability of NADPH which in turn depends on ATP supply within the outer segment. We also suggest that principal source of this ATP is from mitochondria located within the ellipsoid region of the inner segment.

Recombination reaction of rhodopsin in situ studied by photoconversion of "indicator yellow".

We measured the kinetics of recombination of 11-cis-retinal with opsin in intact frog rod outer segment (ROS). The rhodopsin in ROS was bleached and allowed to decay to "indicator yellow," a photoproduct where all-trans-retinal is partly free, and partly bound to non-specific amino groups of disk membranes. By briefly illuminating the "indicator yellow" by an intense 465 or 380-nm flash, we then photoconverted all-trans-retinal to (mostly) the 11-cis- form thus introducing into ROS a certain amount of cis-chromophore. The recombination of cis-retinal with opsin and the formation of rhodopsin were followed by fast single-cell microspectrophotometry. Regeneration proceeded with a time constant of approximately 3.5 min; up to 27% of bleached visual pigment was restored. The regenerated pigment consisted of 91% rhodopsin (11-cis-chromophore) and 9% of presumably isorhodopsin (9-cis-chromophore). The recombination of 11-cis-retinal with opsin inside the ROS proceeds substantially faster than rhodopsin regeneration in the intact eye and, hence, is not the rate-limiting step in the visual cycle.

Two realms of dark adaptation.

The recovery of rod responsiveness after saturating flashes is greatly retarded above a certain critical level of rhodopsin bleaching (approximately 0.1%). A mathematical description of the process of turn-off of the phototransduction cascade allows attributing different phases of the recovery to specific products of rhodopsin photolysis. The fast phase is determined by quenching of metarhodopsin II and activated transducin. The slow phase is controlled by decay of partially inactivated (phosphorylated and arrestin-bound) metarhodopsins, and by regeneration of rhodopsin. The transition between the two regimes of adaptation is rather abrupt, occurring within a few-fold range of stimulus intensity. This marks the border between reversal of light adaptation and dark adaptation, as it is commonly defined.

[Production of DNA-hydrolyzing antibody BV04-01 Fab fragment in methylotrophic yeast Pichia pastoris]. / Produktsiia Fab-fragmenta DNK-gidrolizuiushchego antitela BV04-01 v metilotrofnykh drozhzhakh Pichia pastoris.

Efficient system for producing the recombinant Fab of DNA-hydrolyzing antibody BV04-01 in metylotrophic yeast Pichia pastoris was developed. Addition of peptides encompassing the Jun-Fos leucine zipper at the C-termini of the antibody chains facilitated the in vivo assembling of the Fab. The yield of secreted functionally active BV04-01 Fab was about 3 mg/L. Catalytic efficiency of supercoiled DNA hydrolysis by the Fab obtained was 1.8 x 10(6) M(-1) min(-1).

[Visual cycle and dark adaptation: a new approach in research]. / Tsikl zritel'nogo pigmenta i temnovaia adaptatsiia: novye podkhody k issledovaniui.

Visual cycle is the series of reactions that support regeneration of the visual pigmen after its photolysis in retinal rods and cones. Inherited or acquired deficiencies of the visual cycle impair dark adaptation and lead to a series of visual disorders. The paper describes a new approach to study of the visual cycle that uses fast dichroic microspectrophotometer. The method allows studying interconversion of bleaching products in single intact photoreceptors in condition approaching the situation in vivo. Using this approach, we established a complete scheme of transitions between metarhodopsins, retinal and retinol in amphibian rods. It appeared that the decay of metarhodopsins controls both the time course of rod dark adaptation following small bleaches and the production of retinol that is the substrate for rhodopsin regeneration. We also obtained novel data on kinetics of the decay of cone metapigments that was found to be by an order of magnitude faster than in rods. Possible application of the method for further study of the visual cycle in normal and pathological conditions is discussed.