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For the first time, an analysis of leukocyte changes in the organs of the immune system (pronephros, mesonephros, and spleen) of the Baikal omul Coregonus migratorius (Georgi, 1775) (Salmoniformes: Coregonidae) infected with Dibothriocephalus dendriticus (Nitsch, 1824) (syn. Diphyllobothrium dendriticum) (Cestoda: Diphyllobothriidea) is presented in natural habitat conditions. In the pronephros of infected fish, the number of poorly differentiated neutrophils (myelocytes and metamyelocytes) was significantly higher than in uninfected fish, which indicated inflammatory processes. D. dendriticus triggered the immunoregulatory processes in the body of infected fish, as evidenced by the decrease in the total number of lymphocytes and prolymphocytes (B-lymphocytes) in the pronephros and the increase in prolymphocytes in the spleen. The other effector elements (cells of the monocyte–macrophage lineage, basophils, and eosinophils) were barely involved in antiparasitic defense. [ABSTRACT FROM AUTHOR]

This paper reviews research on the application of equivalent electrical circuits (EEC) for extracting electrochemical parameters of the aluminum alloys oxide coatings. Based on the published research and experimental data gathered by authors we conclude that the most common EEC, applicable to nonsealed coatings and coatings with different sealing, is dual-circuit, consisting of two parallel connected resistors and constant phase elements (CPE). When corrosion damage is introduced the circuit can still be applied except for sufficient degradation of the surface, in which the total impedance is dominated by the double capacitance layer and the impedance can be modeled by the Randles circuit. [ABSTRACT FROM AUTHOR]

The Evevpenta ore occurrence is situated in the northeastern part of the Central Kamchatka volcanic belt (Kamchatka Peninsula, Russia), and lies among andesitic volcanic complexes of the Neogene age. The ore bodies are veins, zones of quartz streaks, and hydrothermal breccias, accompanied by aureoles of argillization which transition into propylites at the periphery. The formation of noble-metal mineralization occurred through two phases: the hypogene (hydrothermal) phase and the hypergene phase. For the hypogene phase we have identified two mineral associations related to noble-metal mineralization: the Central area contains gold—telluride–quartz mineralization, while the Northern area hosts telluride–sulfide–quartz mineralization. The hypergene mineral association with native gold occurs within the Central area only. Based on data relating to the material composition of the ores we show that the Evevpenta ore occurrence is a typical member of epithermal reduction-alkaline or low sulfidation deposits. [ABSTRACT FROM AUTHOR]

The PdII complex was synthesized on the platform of hyperbranched polyester polyphthalate. The polymeric ligand and complex were characterized by different methods, including 1H NMR, IR spectroscopy, electron spectroscopy in the visible and UV ranges, elemental analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), electron microscopy, nitrogen adsorption/desorption, temperature-programmed reduction (TPR) in a hydrogen flow, and XRD. The polymer macromolecule was found to contain ten terminal phthalate groups. The PdII complex is characterized by the ratio ligand: PdII = 2: 5 and contains a square-planar coordination site, which favors the formation of a cluster with the predominant pore diameter from 2 to 10 nm. After the reduction of the PdII complex in a hydrogen flow, Pd0 nanoparticles stabilized on the polymer substrate were obtained. The complex showed a high catalytic activity in the reduction of α-methylstyrene to cumene under mild conditions. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of 1-substituted 5-aryl-1,2,4-triazoles by selective C—H arylation of 1-substituted 1,2,4-triazoles with non-activated aryl chlorides and aryl bromides under the catalysis by a palladium complex with a N-heterocyclic carbene ligand IPr*OMe using 1,1,2,2-tetraphenylethane-1,2-diol (TPEDO) as a catalyst activator is reported. [ABSTRACT FROM AUTHOR]

Free endings of peripheral neurosecretory neurons (NNs) were found in the tegument of plerocercoids of five species of parasitic cestodes of fish in an ultrastructural study. The free terminals secreted vesicles on the tegument surface and into the host body. Secretion was experimentally shown to increase in response to the host fish blood serum. In the cestode body, NNs form paracrine-type contacts near the cell membranes of the frontal glands, the tegument, and muscles, functioning as endocrine glands. Simultaneously, NNs function as exocrine glands and secrete the so-called manipulative factors, which influence the physiology of the host. [ABSTRACT FROM AUTHOR]

A second-generation hyperbranched polyester with the terminal carbamoyl phosphonate groups has been synthesized. The structure of the resulting polyester has been studied by IR, 1H NMR, 31P NMR, and electron spectroscopy. It has been found that 25% of the terminal OH groups of polyester polyol were subjected to functionalization. Using the TGA method, the thermal stability temperature of the resulting polyester was evaluated to be 138°C. We have synthesized a complex of the resulting polyester with the Pd(II) ions, and the complex structure has been studied by IR and electron spectroscopy. The composition of the ligand–Pd(II) complex has been evaluated to be 1 : 6. We have found by the TGA method that this complex is thermally stable up to 207°C. The temperature of reduction of the Pd(II) ions by molecular hydrogen to Pd(0) has been assessed as –20.6°C. Electron microscopy has been used to demonstrate the spherical morphology of hyperbranched polyester polycarbamoyl phosphonate with Pd(0) atoms, with the predominant fraction being 1.5 μm. It has been shown that the use of hyperbranched polyester polycarbamoyl phosphonate as a catalyst provides the activation energy of 55.8 kJ/mol for hydrogenation of α-methylstyrene to cumene with the effective rate constant of 1.950×10–2 L/(gcat s) at 45°C and atmospheric pressure. The results indicate the prospects of using hyperbranched polyester polycarbamoyl phosphonate as a matrix to obtain catalysts for the hydrogenation of unsaturated compounds. [ABSTRACT FROM AUTHOR]

In this work, the anti-inflammatory potential of secretory-excretory products (SEP) of gull-tapeworm Dibothriocephalus dendriticus and Ligula Ligula interrupta plerocercoids was studied for the first time in an in vitro model of LPS-induced activation of macrophages. A monocyte cell line derived from a patient with acute monocytic leukemia, THP-1, was used as a macrophage model. The anti-inflammatory properties of SEP were determined by the content of tumor necrosis factor (TNF) and interleukin-6 cytokines in the incubation medium using commercial kits for enzyme immunoassay. The results of our study indicated that SEP from L. interrupta plerocercoids have a pronounced anti-inflammatory effect, while SEP from D. dendriticus plerocercoids did not have such an effect. The authors next investigated the anti-inflammatory properties of L. interrupta SEP in a carrageenan-induced air-sac inflammation model in mice. A significant decrease in the volume of inflammatory exudate under the influence of L. interrupta SEP was found as well as an increase in the level of the interleukin-6 cytokine. At the same time, SEP of L. interrupta had no effect on the number of cells per 1 mL of exudate or the level of the proinflammatory cytokine TNF. The low molecular weight fraction of L. interrupta SEP also increased the level of the anti-inflammatory cytokine interleukin-10, which indicates a more pronounced anti-inflammatory effect compared to the high molecular weight fraction. The results obtained, in general, indicate the anti-inflammatory properties of the SEP of L. interrupta plerocercoids. However, the mechanism of anti-inflammatory action has not been elucidated and requires further research. [ABSTRACT FROM AUTHOR]

The new mineral nishanbaevite, ideally KAl2O(AsO4)(SO4), was found in sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with euchlorine, alumoklyuchevskite, langbeinite, urusovite, lammerite, lammerite-β, ericlaxmanite, kozyrevskite, and hematite. Nishanbaevite occurs as long-prismatic or lamellar crystals up to 0.03 mm typically combined in brush-like aggregates and crusts up to 1.5 mm across. It is transparent, colourless, with vitreous lustre. Dcalc = 3.012 g cm− 3. Nishanbaevite is optically biaxial (–), α = 1.552, β ≈ γ = 1.567. The chemical composition (average of seven analyses) is: Na2O 3.79, K2O 8.01, CaO 0.10, CuO 0.21, Al2O3 30.08, Fe2O3 0.50, SiO2 1.62, P2O5 0.66, As2O5 32.23, SO3 22.59, total 99.79 wt%. The empirical formula calculated based on 9 O apfu is: (K0.57Na0.41Ca0.01)Σ0.99(Al1.99Fe3+0.02Cu0.01)Σ2.02(As0.95S0.95Si0.09P0.03)Σ2.02O9. Nishanbaevite is orthorhombic, Pbcm, a = 15.487(3), b = 7.2582(16), c = 6.6014(17) Å, V = 742.1(3) Å3 and Z = 4. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 15.49(100)(100), 6.56(30)(110), 4.653(29)(111), 3.881(54)(400), 3.298(52)(002), 3.113(29)(121), and 3.038(51)(202, 411). The crystal structure, solved from single-crystal XRD data (R = 7.58%), is unique. It is based on the complex heteropolyhedral sheets formed by zig-zag chains of Al-centred polyhedra (alternating trigonal bipyramids AlO5 and octahedra AlO6 sharing edges) and isolated tetrahedra AsO4 and SO4. Adjacent chains of Al polyhedra are connected via AsO4 tetrahedra to form a heteropolyhedral double-layer. Its topological peculiarity is considered and compared with those in structurally related compounds. The (K,Na) site is located in the interlayer space between SO4 tetrahedra. The position of nishanbaevite among the arsenate-sulfates and their specific structural features are discussed. The mineral is named in honour of the Russian mineralogist Tursun Prnazorovich Nishanbaev (1955–2017). [ABSTRACT FROM AUTHOR]

In the course of the three waves of the seventh cholera pandemic, the genome of the pathogen has undergone significant changes, which resulted in the emergence of new genetic variants with a high pathogenic and epidemic in the last decade. The aim of this study is to investigate the genomic diversity of the cholera agent and the prevalence of new genetic variants both in cholera-endemic regions and Russia, as well as to identify their phylogenetic relations. To search for new variants of the pathogen, bioinformatic analyses of the whole genome nucleotide sequences of 124 V. cholerae El Tor strains have been carried out. These strains were previously obtained by us or taken from the NCBI Gen Bank and European Nucleotide Archive database. Phylogenetic relations have been established based on SNP analysis for 115 different strains isolated in Asia, Africa, Russia, and Ukraine during three waves of the pandemic. Genomic analyses have been performed for 91 strains isolated in seven endemic countries between 2007 and 2019. According to the sets of mutant virulence and epidemicity genes localized in mobile genetic elements (CTXφ prophage, pathogenicity island VPI-1, and pandemic island VSP-II) and the core region, 74.7% of the studied strains are classified as new genetic variants of the pathogen. The genomic analyses of toxigenic strains from Russia and Ukraine (1970–2014) have revealed five groups that differ in mutations in key genes associated with virulence, epidemic potential, and drug resistance. According to the spectrum of mutant genes, 80.0% of the strains imported from endemic regions in recent years (2010–2014) have been recognized as new variants. According to the analysis of phylogenetic relations based on SNP typing of 115 strains, the new variants from Russia and Ukraine are phylogenetically similar to those circulating in Africa and Asia over the past decade. The results obtained are of interest for understanding the molecular mechanisms and dynamics of changes in the most important genetic properties of this pathogen and can also be used to develop methods for gene diagnostics of new variants of the pathogen. [ABSTRACT FROM AUTHOR]

Tapeworms of the genus Dibothriocephalus are widely distributed throughout the world, some of which are agents of human diphyllobothriasis, one of the most important fish-borne zoonoses caused by a cestode parasite. Genomic and transcriptomic data can be used to develop future diagnostic tools and epidemiological studies. The present work focuses on a comparative analysis of the transcriptomes of adult and plerocercoid D. dendriticus and the identification of their differentially expressed genes (DEGs). Transcriptome assembly and analysis yielded and annotated 35,129 unigenes, noting that 16,568 (47%) unigenes were not annotated in known databases, which may indicate a unique set of expressed transcripts for D. dendriticus. A total of 8022 differentially expressed transcripts were identified, including 3225 upregulated and 4797 downregulated differentially expressed transcripts from the plerocercoid and adult animals. The analysis of DEGs has shown that among the most differentially expressed genes, there are important genes characteristic of each stage. Thus, several genes are characteristic of D. dendriticus plerocercoids, including fatty acid–binding protein and ferritin. Among the most highly expressed DEGs of the adult stage of D. dendriticus is the Kunitz-type serine protease inhibitor, in two putative isoforms. The analyses of GO and KEGG metabolic pathways revealed that a large number of the DEGs of D. dendriticus are associated with the biosynthesis of various substances such as arginine and folate, as well as with various metabolic pathways such as galactose metabolism, selenocompound metabolism, and phosphonate and phosphinate metabolism. This will contribute to further research aimed at identifying targets for new generation drugs and the development of specific vaccines. [ABSTRACT FROM AUTHOR]

A highly efficient hybrid adsorbent has been synthesized, which is based on an industrially available biodegradable nontoxic flax cellulose modified with hyperbranched polyester polybenzoylthiocarbamate. The synthesis has been carried out using toluene diisocyanate (TDI) as a linker. The second-generation hyperbranched polyester polybenzoylthiocarbamate contains eight terminal benzoylthiocarbamate and eight hydroxyl groups according to 1H NMR, 13C NMR, and IR spectroscopy. In the first stage, the reaction of TDI with flax cellulose has been carried out, which provided 27% content of TDI according to potentiometric titration. The resulting modified flax cellulose has reacted with hyperbranched polyester polybenzoylthiocarbamate. The content of hyperbranched polymer in cellulose (5%) has been evaluated by the weight method. The unreacted isocyanate groups have been neutralized with isobutyl alcohol. The structure of the hybrid material has been proven by IR spectroscopy. The adsorption properties of the polydentate adsorbent have been studied with for the Cu(II) ions. It has been found that the adsorption capacity of the adsorbent is 6.93 mg/g. The methods of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been used to evaluate the temperature characteristics, thermal effects, and mass loss of the obtained polydentate compound and its complexes. Desorption of the Cu(II) and Co(II) ions with the regeneration of the hybrid adsorbent has been shown to occur in an acidic medium at pH 3–4. [ABSTRACT FROM AUTHOR]

Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (greater than two seconds) duration are produced by the core-collapse of massive stars1, and those of short (less than two seconds) duration by the merger of compact objects, such as two neutron stars2. A third class of events with hybrid high-energy properties was identified3, but never conclusively linked to a stellar progenitor. The lack of bright supernovae rules out typical core-collapse explosions4–6, but their distance scales prevent sensitive searches for direct signatures of a progenitor system. Only tentative evidence for a kilonova has been presented7,8. Here we report observations of the exceptionally bright GRB 211211A, which classify it as a hybrid event and constrain its distance scale to only 346 megaparsecs. Our measurements indicate that its lower-energy (from ultraviolet to near-infrared) counterpart is powered by a luminous (approximately 1042 erg per second) kilonova possibly formed in the ejecta of a compact object merger.A bright, long-duration gamma-ray burst observed by the Swift observatory has hybrid high-energy properties, suggesting that its origin is the merger of a compact binary. [ABSTRACT FROM AUTHOR]

Recently, hyperbranched polymers (HBPs), which differ significantly in structure and properties from linear, cross-linked and branched analogs, have become increasingly important. HBP have a spatial unloaded core and a shell of branched monomer units (dendrons), in which functional groups are predominantly located in the surface layer. The size of macromolecules ranges from 2 nm to 100 nm. Currently, there are a fairly large number of publications in the literature devoted to the modification of hyperbranched polyester polyols with various functional groups and the assessment of the potential for their use. However, there are no review articles on this topic in recent years. In this regard, it is relevant to generalize the latest achievements in the field of synthesis, properties and application of hyperbranched polyester polyols with terminal oxygen, nitrogen, silicon, sulfur and organophosphorus fragments. The advantage of hyperbranched polyester polyols of the Boltorn H series is their industrial availability, biodegradability, nanoscale, non-toxicity and high solubility in various polar solvents due to short monomer units, as well as the presence of reactive terminal hydroxyl groups. Functionalization of hyperbranched polyester polyols at hydroxyl groups is mainly carried out by addition of acid anhydrides, iso(thio)cyanates, alkenes, lactides, lactones, lactams, epoxy compounds or reactions with halogenated compounds (alkyl halides, acid chlorides). In some cases, for the functionalization of polyester polyols special linkers are used, such as acid chlorides of unsaturated or dicarboxylic acids, diisocyanates, etc., which provide covalent bonding of the hyperbranched polymer with the target functional group. The obtained derivatives of hyperbranched polyesters are widely used in such areas as biomedicine, pharmacy, paints and varnishes, they are also used as catalysts, membranes, multifunctional coatings, plasticizers and polymer stabilizers. [ABSTRACT FROM AUTHOR]

Abstract—The possibility of determining the degree of corrosion damages of various types by the eddy current control method using a laid-on probe is considered. A two-frequency method is proposed for separate control of the degree and type of corrosion damages. A method for selecting frequencies for monitoring is described. The developed method of estimating the degree of corrosion damage is experimentally tested. [ABSTRACT FROM AUTHOR]

The cytomorphological parameters of hemopoietic organs (pronephros and spleen) of crucian carp (Carassius auratus L., 1758) infected with Ligula (Digramma) interrupta (Logan, 2004) are studied for the first time. The biological material has been obtained from fish in Dolgoe and Cheremukhovoe lakes (the Lake Baikal basin, Buryatia) with an unfavorable digrammosis situation. Infection with plerocercoids causes a hematopoietic transformation: the compensatory activation of erythropoiesis in the pronephros against the background of a low number of mature erythrocytes and a decrease in the proliferative activity of erythroid elements in the spleen. [ABSTRACT FROM AUTHOR]

Changes in impedance spectra of hot-water sealed and unsealed coatings at the aluminum alloy from the Al–Cu–Li–Zn-system during their corrosion testing in NaCl solution and salt spray chamber are studied. During the testing in NaCl solution, the coatings' barrier properties are severely degraded after the appearance of corrosion damage spots, which manifests itself in the lowering of the impedance modulus in low-frequency region. The NaCl solution induced rapid growth of corrosion area, the more so, for the unsealed coating. Compared to the NaCl solution testing, the growth of corrosion spots is by order of magnitude slower for the salt-spray testing, at which the isolated corrosion damage spots are prevailing. [ABSTRACT FROM AUTHOR]

Ural-Alaskan-type zonal mafic–ultramafic complexes are the predominant source of platinum-group minerals (PGM) in alluvial deposits worldwide. Processes responsible for the formation of mm-sized grains of Pt-Fe alloys within these deposits remain a subject of ongoing debate. In this study, the 190Pt-4He dating method is applied to isoferroplatinum from the Ural-Alaskan-type Matysken, Itchayvayam, and Filippa complexes of the Koryak-Kamchatka Platinum Belt in order to determine the timing of Pt mineralization and its relation to the regional and local geologic history of the source rocks. Results of 190Pt-4He dating indicate multistage Pt mineralization, with at least two generations recognized. The first generation (70 ± 2 Ma and 77 ± 2 Ma for the northern and southern parts of the Belt, respectively) is contemporaneous with intra-oceanic arc magmatism, which resulted in the formation of the dunite-clinopyroxenite complexes. The second generation is significantly younger (~ 64 Ma), and reflects a later mineralization or recrystallization event following the termination of active volcanism within the Olyutorsky Arc evolution. [ABSTRACT FROM AUTHOR]

A new adsorbent based on powdered linen cellulose modified with hyperbranched polyester with terminal benzoyl thiocarbamate groups has been synthesized. Complexes with Cu(II) and Co(II) ions have been obtained. The structure of the adsorbent and complexes has been established by IR spectroscopy and potentiometric titration. The adsorption capacity of the adsorbent and conditions for its regeneration from the complexes have been estimated. [ABSTRACT FROM AUTHOR]

The aim of the study is to analyze the variability of multiple antibiotic resistance caused by variations in the mobile SXT element and chromosomal gene mutations in various strains of the cholera agent isolated in Russia and endemic cholera foci. Based on bioinformatic analysis of the whole genome nucleotide sequences of 110 clinical strains of V. cholerae El Tor isolated in different regions, the structure of their integrative conjugative SXT elements was determined. Mutations in the chromosomal antibiotic-resistance genes gyrA, parC, and carR were identified. Phylogenetic analysis of strains containing different types of SXT was carried out. It was shown that the variability of multiple antibiotic resistance in the studied strains from Russia and Ukraine was associated with the presence in the chromosome of two types of SXT elements with different compositions of resistance genes and spontaneous chromosomal mutations in the gyrA, parC, and carR genes, which determine resistance to nalidixic acid and polymyxin B. At the same time, five types of SXT were found in the studied strains from Asian and African countries, which determined a higher level of variability of their antibiotic resistance. Based on SNP analysis, an assessment of the phylogenetic relationships of isolates with different types of SXT and different chromosomal mutations is given. The data obtained indicate that the variability of cholera-agent resistance to antibiotics is provided by different types of SXT and mutations in chromosomal genes. The revealed high level of SXT genomic diversity in the V. cholerae population in cholera-endemic regions indicates the threat of importation of new cholera-agent strains with previously unknown antibiotic resistance into Russia. [ABSTRACT FROM AUTHOR]

A new hybrid adsorbent has been synthesized by covalent linking of activated zeolite with hyperbranched polyester containing 8 terminal N-benzoylthiocarbamate groups. The structure of the polymer ligand was defined by IR, 1H and 13C NMR spectroscopy. The complexing properties of the adsorbent have been studied using the example of complexes with Cu(II) and Co(II) ions. It was proved by IR spectroscopy that N-benzoylthiocarbamate and toluylenecarbamate groups participate in complexation with metal ions. According to electron microscopy and porometry data, the average particle diameter of the adsorbent is 34.56 μm and the mesopore diameter is 4.19 nm. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have shown that the hybrid adsorbent is thermally stable up to 150 °C. The sorption capacities of the adsorbent for Cu(II) and Co(II) ions are 31.92 and 17.7 g/kg. It was shown that the desorption process of metal ions from the complexes occurs in an acidic medium at pH 4 with the regeneration of the original adsorbent. [ABSTRACT FROM AUTHOR]

Abstract—This paper focuses on new data for palladium-bearing mineral phases in the ores of the Malmyzh porphyry gold–copper deposit situated approximately 220 km northeast of Khabarovsk in the Russian Far Eas. The Malmyzh area comprises the Early Cretaceous terrigenous sediments, which are intruded by the Albian to Cenomanian diorite and granodiorite stocks. The platinum group minerals (PGM), sopcheite, merenskyite, kotulskite, naldrettite, and arsenopalladinite, were identified during a detailed study of chalcopyrite veinlets at the Freedom site of the Malmyzh porphyry Cu–Au deposit. The relationship with other minerals indicates that these PGM are later than chalcopyrite. [ABSTRACT FROM AUTHOR]

On the initiative of the PJSC Mosenergo, possible alternatives of cooling of cycle air of the gas-turbine units of the combined-cycle power plant (CCPP) were compared within the framework of the 2015 feasibility study and the 2017 research and development (approved at Techncial Expert Council No. 13 of the LLC Gazpromenergoholding) to choose a unit with an evaporative cooler manufactured by the Roxor company (Sweden – Russia). In the period from 10/30/2018 to 11/30/2018, construction and installation work was carried out, followed by the installation of evaporator and moisture-trap cassettes in the period from 5/20/2019 to 5/24/2019 (planned shutdown of the CCPP). The results of tests intended to determine the efficiency of the evaporation unit in the climatic conditions of Moscow and to develop a parameter chart for CCPP-450 unit of Mosenergo CHPP-20 are presented. Recommendations on further use of such installations in the Mosenergo power system are given. [ABSTRACT FROM AUTHOR]

Results of a microstructural study of spinel peridotite samples obtained from the Kraka massif in the Southern Urals, involving findings of Cr-spinel neomineralisations within intensive ductile deformed silicates (olivine and orthopyroxene), are presented. The new-formed Cr-spinel grains show different stages of syn-deformation growth as evidenced by investigations combining petrography, decorated dislocation structure analysis, scanning electron microscopy and electron backscatter diffraction (EBSD). Initial precipitations appearing as rods or lamellae are observed to form around structural defects of host silicate grains (olivine and orthopyroxene) by means of impurity segregation or heterogeneous nucleation in the most distorted lattice regions (i.e., in the predominant recrystallisation zones). Syn-deformational crystal growth leads to a complication and coarsening of the grain morphology by coalescence due to a reduction in grain boundary (interfacial) energy. While in the process of growing, the Cr-spinel grains capture fragments of silicate matrix in the solid-state process. The final stage of Cr-spinel growth involves a change in morphology resulting in their characteristic crystallographic forms (spheroidisation). The presence of euhedral Cr-spinel grains, typical for ophiolitic dunite bodies, is a result of interfacial energy reduction in areas of grain boundaries of the hardest phase. The general trend of the observed stages relates closely with the localisation of deformation zones in the upwelling upper mantle (diapir), which are composed by the weakest phase of olivine (dunites). The concentration of the weakest olivine phase in the mobile zones, which is energetically beneficial, explains why dunite bodies having euhedral chromite grains comprise the dynamic equilibrium rocks in the plastic flow localisation zones in upper mantle diapirs. Conversely, assemblages having pyroxene phases, which are stronger and larger in size compared to olivine, are not stable in these zones. [ABSTRACT FROM AUTHOR]

The article presents the first U-Pb (SHRIMP–II) zircon age data on dikes cutting dunite of the Kamenushinsky dunite–clinopyroxenite–gabbroic massif in the Ural Platinum Belt. The dikes are made up of gabbro-pegmatite, hornblendite, and granite, the field relations between which suggest their subsequent intrusion in the dunites. Their geochemical features show that they belong to two different magmatic series. The gabbro–pegmatite is the derivatives of the dunite–clinopyroxenite–gabbro series, while hornblendites are the derivatives of the gabbro series. At the same time, the granite corresponds to anatectic granites developed within the Platinum Belt. U-Pb zircon dating of the gabbro yielded an age of 418.3 ± 4.5 Ma, which can be considered as the upper age limit of the dunite–clinopyroxenite–gabbro series. The age of the hornblendite of 421.0 ± 2.4 Ma is close to the age of the majority of the gabbroic rocks of the Ural Platinum Belt. The U-Pb zircon dating of the granite yielded a relatively young age of 384.9 ± 0.5 Ma. This testifies the continuation of the intrusive magmatic activity within the Ural Platinum Belt after the formation of the youngest volcanic rocks of the Tagil volcanic arc, the gabbro–diorite–granite intrusions of the Auerbakh Complex, and significantly expands the time range of magmatism associated with partial melting of the gabbro protolith directly within the belt. [ABSTRACT FROM AUTHOR]

A new hybrid adsorbent based on zeolite modified with hyperbranched polyesterpolybenzoylthiocarbamate is presented. The structure and morphology of the sorbent are characterized by potentiometric titration, IR, 1H and 13C NMR spectroscopy, and electron microscopy. The fundamental possibility of extracting transition metal ions has been demonstrated using the examples of CuII and CoII ions. It is shown that the sorption capacity of the adsorbent to CuII salt is 25.34 mg g−1. A method of sorbent regeneration is proposed. [ABSTRACT FROM AUTHOR]

The genomic instability of the cholera agent leads to the emergence of its new variants with altered epidemically significant features. This makes investigation of the dynamics in pathogenicity gene structure and cholera vibro persistence changes over extended periods of time important. Bioinformatic analysis of whole genome nucleotide sequences was carried out in 44 toxigenic and nontoxigenic Vibrio cholerae O1 strains, biovar El Tor, isolated before the onset and in different periods of the current pandemic, with 29 of them being found in Russia. SNP-typing was performed using Bayesian evolutionary analysis with BEAST v2.5.1. Based on SNP-analysis, it was demonstrated that the importation of epidemically hazardous strains into the territory of Russia (1970–2014) overlapped with three different waves of the global spread of cholera. Comparison of the nucleotide sequences of genomic regions determining their virulence and ability to spread epidemically confirmed that there were multilayered rapid changes in cholera vibrios during evolution. For the first time ever, it has been established that the genomes of pathogenicity islands, VPI-1 and VPI-2, of prepandemic strains contained different mutations, which distinguish them from the genome of pandemic strains. At the same time, we have revealed conservation of nucleotide sequences of all the studied persistence genes from VPI-2 and EPI of pandemic isolates. On the contrary, the modern nontoxigenic strains ctxA–tcpA– show considerable variability of persistence genes that are parts of the structure of these mobile elements. New data on the structure of regions of the V. cholerae genome associated with persistence can be used to differentiate V. cholerae of different epidemic significance. [ABSTRACT FROM AUTHOR]

The Epilchik Ural-Alaskan type mafic-ultramafic zoned complex, located in the northernmost part of the Koryak-Kamchatka Platinum Belt (Russian Far East), contains lode platinum mineralization. The outcrops of the complex are crossed by the Snegovaya River, which hosts placer platinum-group minerals (PGM) occurrences. The primary PGM assemblage of the Epilchik lode chromitites is typical for Ural-Alaskan type complexes, dominated by Ir-rich isoferroplatinum which occurs as small euhedral inclusions within chromite. Secondary alloys include tetraferroplatinum (PtFe), tulameenite (Pt2FeCu), an unnamed Fe3Pt compound, and Pt-bearing native iron, which form alteration rims around isoferroplatinum or occupy fractures in chromite. Other secondary minerals from lode chromitites are hollingworthite (RhAsS) and Os-Fe alloy ("hexaferrum"). The PGM assemblages of the Snegovaya River placer occurrences are comparable with those of the lode chromitites with a predominance of Ir-rich isoferroplatinum and secondary alloys, including tetraferroplatinum, tulameenite, and an unnamed Fe3Pt compound. However, placer occurrences are much richer in regard to mineral diversity, comprising native osmium (Os,Ir), native iridium (Ir,Os), laurite (RuS2), erlichmanite (OsS2), cuprorhodsite (CuRh2S4), cuproiridsite (CuIr2S4), Co-malanite (Cu(Pt,Co)2S4), unnamed sulfides Rh3S4, (Rh,Pt)S, sperrylite (PtAs2), platarsite (PtAsS), irarsite (IrAsS), hollingworthite (RhAsS), osarsite (OsAsS), cooperite (PtS), native gold, unnamed telluride (Pt2Te), and an unnamed Fe-Ir-Rh alloy. Similarities between lode and placer mineralization indicate that the Epilchik complex was the dominant source for the placers. The larger diversity of PGM in placers may be attributed to the heterogeneity of samples which could be derived from unsampled or unexposed outcrops of the complex. Alteration of isoferroplatinum to secondary intermetallic compounds occurred via progressive development of reduced conditions as a result of serpentinization. Subsequent pervasive As-mineralization redistributed platinum-group elements, including Os and Ir. A final mineralizing pulse deposited sporadic native gold and Pt telluride minerals. A comparison of key mineralogical and physical features between the Epilchik complex and other Ural-Alaskan type complexes is used to determine the economic potential for placers along the Snegovaya River. Key criteria include (1) the size and degree of erosion of the outcrop area of the complex; (2) the predominance of isoferroplatinum over native platinum; (3) high Ir content in Pt-Fe alloys; and (4) the predominance of secondary intermetallic compounds over sulfides. Based on these criteria, the occurrences associated with the Epilchik complex are considered prospective for high volume and economic grade accumulations of PGE. This method is useful for assessing the economic potential of placer occurrences during indirect early-stage prospecting with a limited sample suite. [ABSTRACT FROM AUTHOR]

The change in the composition of the protein fraction of Diphyllobothrium dendriticum (Cestoda) plerocercoids during incubation in a medium containing blood serum of their host—the Baikal omul Coregonus migratorius (Coregonidae)—was investigated. The change in the composition of the protein fraction of the incubation medium also was studied. On the one hand, the appearance of new high-molecular fractions with a molecular weight (MW) of 193 kDa after 3, 12, and 24 h of incubation and 88 kDa after 24 h was detected, which was associated at plerocercoids with the appearance of a new 189 kDa fraction after 12 h and the disappearance of the 80 kDa fraction. On the other hand, a decrease or the disappearance of two low-molecular fractions 57 and 42 kDa in the incubation medium after 3, 12, and 24 h of incubation were observed. [ABSTRACT FROM AUTHOR]

The results of comparative sequence analysis of pathogenicity islands (PIs), VPI-1 and VPI-2, in 43 nontoxigenic Vibrio cholerae strains are presented. It was demonstrated that these strains, differing from each other in the PI genome composition and structure, formed three genetically distinct groups (ctxA−tcpA+VPI-2+, ctxA−tcpA+VPI-2del+, and ctxA−tcpA−VPI-2del+) that differed in adaptive potential. It was found that the level of PI genomic variability caused by point mutations and deletions of different lengths was different. Nucleotide sequences of the VPI-1 structural and regulatory pathogenicity genes present in the chromosome of nontoxigenic ctxA−tcpA+ vibrios were mostly identical to that of the reference toxigenic strain. Only a small number of polymorphic sites (5) with single nucleotide substitutions in the acfB, асfС, tcpА, tcpF, and tcpH genes were identified. At the same time, high VPI-2 genomic instability, manifested in the formation of deletions of different lengths (31 131–49 986 kb) and the occurrence of multiple single nucleotide substitutions in all conserved genes, was observed. It was first demonstrated that the loss of VPI-2 DNA correlated with the appearance of multiple substitutions in its genes of utilization of amino sugars and sialic acids, located in the nan-nag region (57–274 substitutions), including the nanH gene. Twelve previously undescribed nanH allelic variants were identified. It seems likely that high genetic diversity of these genes that are important for the vibrio survival in different ecological niches is one of the reasons for high adaptive potential of V. cholerae O1 biotype El Tor сtxA−tcpA−VPI-2del+, ubiquitous in an aquatic environment. On the basis of sequence analysis of the nanH gene included in VPI-2, as well as six housekeeping genes, cluster analysis that determined the phylogenetic relationships of different groups of nontoxigenic strains with each other and with toxigenic strains was performed. The genetic closeness of nontoxigenic ctxA−tcpA+VPI-2+ and ctxA−tcpA+VPI-2del+ vibrios to the causative agent of cholera was discovered. The novel data obtained in the present study on the PI structure in nontoxigenic vibrios not only shed light on the molecular mechanisms of genetically diverse strains with different adaptive potentials. Nontoxigenic strains with the determined genome structure that do not require the removal of key virulence genes upon genome editing can be useful in creating a new generation of live cholera vaccines. [ABSTRACT FROM AUTHOR]

The structures of ethyl 2,2-bis{[(benzoylcarbamothioyl)oxy]methyl}propanoate and its 1 : 1 complexes with copper(II) and cobalt(II) ions were determined by electronic absorption, IR, and 1H and 13C NMR spectroscopy and elemental analysis. The coordination entity in the complexes includes oxygen and sulfur atoms of the benzoyl and carbamothioyloxy groups of both ligand branches. The copper(II) ion has octahedral configuration with trigonal distortion, and the cobalt(II) ion has five-coordinate square–pyramidal configuration. The thermal behavior of the title compounds was studied by differential scanning calorimetry and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

The paper reports the investigation of the population structure of Yersinia pestis strains belonging to the ulegeica subspecies (genetic branch 0.PE5), which is endemic to the natural plague foci in Mongolia and which is characterized by low epidemic potential compared to the strains belonging to the main plague subspecies. Whole genome SNP analysis of 12 Y. pestis subspecies ulegeica strains isolated in Mongolia considering the 1581 identified core SNPs revealed two main genetic clusters in correspondence with the geographic distribution of these strains. The first cluster, named 0.PE5/1, contains the strains isolated in the Umnegov', Uverkhangai, and Gov'-Altai aimaks located in the south of Mongolia. The second cluster 0.PE5/2 comprises two subclusters, namely, 0.PE5/2-1, containing the strains from the Bayan-Ulgii and Khovd aimaks, and 0.PE5/2-2, represented solely by the strains isolated in the Bayan-Ulgii aimak. To find the possible causes of the selective virulence of subspecies ulegeica strains, the analysis of the nucleotide sequences of 79 pathogenicity factors along with some other genomic regions has been carried out. Specific mutations have been found in the following genes: irp1, included in the high-pathogenicity island of the chromosomal pigmentation region, and yscQ, involved in the regulation of the synthesis of the LcrV protein and outer membrane proteins (Yops) associated with plague pathogen virulence. [ABSTRACT FROM AUTHOR]

High genomic variability of cholera pathogen, which is capable of persisting in the human organism and aquatic environments, underlies the diversity of virulent properties of its strains. However, the mechanism of emergence of the El Tor biovar Vibrio cholerae O1 strains with altered virulence remains poorly understood. A total of 21 El Tor biovar V. cholerae O1 strains were studied. Protein electrophoresis, enzyme-linked immunosorbent assay (GM1-ELISA), whole-genome sequencing, genomic analysis, and SNP genotyping were employed to study their properties. The virulence of the strains was assessed via intestinal infection of model animals. This paper reports that the genome of avirulent V. cholerae O1 strains of the El Tor biovar isolated from the aquatic environment contains the CTXφ prophage and VPI-1 pathogenicity island, which contain the ctxAB and tcpA-F genes, respectively, encoding the key pathogenicity factors, namely, the cholera toxin and toxin-coregulated pili. Comparative analysis of the nucleotide sequences of these mobile elements' genomes from two avirulent strains (89 and 147) of the ctxA+tcpA+ genotype and five clinical virulent isolates of the same genotype has not revealed any differences between them. At the same time, a change in the nucleotide sequence of the toxR global regulator gene located in the core region of pathogen's genome has for the first time been detected in avirulent strains. This was a single nucleotide deletion (T in position 357), which resulted in the formation of a TGA stop codon. The consequence of such mutation is the production of defective transmembrane DNA-binding protein ToxR that positively regulates the toxT main virulence regulator gene expression due to the loss of 176 amino acids. It has been demonstrated that the loss of toxR protein function resulted in a significant decrease of the mRNA levels of the key regulatory (toxR and toxT) and structural (ctxA, ctxB, and tcpA) virulence genes in the studied strains. As a result, the expression of the cholera toxin genes in the mutant strains 89 and 147 was more than 20 times lower compared to the virulent strains. Whole-genome SNP analysis of the strains 89 and 147, as well as of 19 virulent strains including different genetic variants of the pathogen was carried out to infer their phylogenetic relationships. A new mechanism for the virulence change in cholera vibrio strains has been identified. A change in the nucleotide sequence of the toxR global regulator gene has been demonstrated in the avirulent strains of the ctxA+tcpA+ genotype. This mutation resulted in the formation of a defective transmembrane DNA-binding protein ToxR, which caused a dramatic decrease in the production of the toxin required for the development of the cholera disease. [ABSTRACT FROM AUTHOR]

Syntheses of a polydentate ligand based on the second-generation hyperbranched polyester containing 3-(2-aminoethyl)amino]propionate groups and its metal complex with copper(II) ions have been elaborated. In view of the IR, electronic absorption, and EPR spectroscopy data, it has been suggested that the coordination sites in the metal-polymer complex are paramagnetic sites with the CuN4Solv2 or CuN2O2Solv2 composition (Solv = H2O, DMSO). [ABSTRACT FROM AUTHOR]

The interaction of Co(NO3)2 and Cu(NO3)2 with hyperbranched polyester containing 7 terminal benzoyl thiocarbamate groups has been studied by IR-Fourier and electron absorption spectroscopy. А new polynuclear complexes of Co(II) and Cu(II) with poly(benzoyl thiocarbamate)-modified hyperbranched polyester have been synthesized. It has been found that the oxygen and sulfur atoms of the peripheral benzoyl thiocarbamate fragments of the macroligand are involved in coordination with metal ions, the metal to ligand ratio being 7 : 1. [ABSTRACT FROM AUTHOR]

The cytomorphological composition of the blood and mesonephros of goldfish infected with Ligula interrupta has been studied under the conditions of the native range. A decrease in the total number of leukocytes and neutrophils in the blood at all stages of development and deregulation of the proliferation and differentiation of lymphoid, pseudo-eosinophilic, and pseudo-basophilic elements in the studied organs are established. Infiltration of neutrophilic mesonephros by low-differentiated forms is observed. It has been shown that, in this parasitic system, the partner relations cause the launch by L. interrupta of mechanisms that regulate the host immune response by inhibiting the acute inflammatory response and the development of mild chronic inflammation. B-cell activation in the immune response is accompanied by processes of cellular degeneration and immunosuppression, factors that are actively involved in cytotoxic reactions. [ABSTRACT FROM AUTHOR]

The paper presents new geological, petrological, and geochemical data on the dunite–clinopyroxenite–gabbro massifs of the Tamanvayam area. The time of formation of the intrusions is specified using U–Pb zircon dating. The Machevna Massif is mainly composed of gabbroids and clinopyroxenites, which are related by gradual facies transitions and intruded by amphibole gabbro, leucogabbro, and monzogabbro. The youngest rocks, cutting across all of the above-described varieties, are granites and granodiorites (tonalites), which make up composite injection bodies and small stocks in the central part of the massif. According to the new U–Pb dates, all of the intrusive rocks of the Machevna and Poputny intrusions were formed in a narrow time range of 73.1–67.7 Ma. The obtained range overlaps the formation interval of the siliceous volcanogenic sequences of the Achaivayam Formation (biostratigraphic studies, retrospective data). The geochemical similarity of the gabbroids and pyroxenites with intersecting amphibole gabbros and leuco- and monzogabbros allows us to attribute them to a single magmatic complex. The geochemical affinity and the penecontemporaneous formation of the intrusive rocks of the Tamanvayam area and volcanics of the Achaivayam Formation indicate their formation during a single tectonomagmatic event. At the same time, the gabbroids and pyroxenites can be considered as comagmatic rocks of the basalts and picrobasalts of the Achaivayam Formation. The high-Ca picrobasalts of the Achaivayam Formation that developed near the Machevna intrusion were presumably derived from parental melts of concentrically zonal massifs. [ABSTRACT FROM AUTHOR]

We have investigated the population structure of Yersinia pestis spp. caucasica strains from natural plague foci located in the Caucasus and Transcaucasia. According to the data of a whole genome SNP analysis of 28 strains of the Caucasian subspecies, seven of which are sequenced by us, and taking into account 1625 identified core SNPs, the presence of several phylogenetic lines and populations of Yersinia pestis ssp. caucasica corresponding to the geographical distribution of the strains has been determined. Strains of Y. pestis Caucasian subspecies include three separate clusters, the first of which is represented by strains from the East Caucasian high-mountain plague focus. Their genome has revealed 80 unique SNPs, which indicates their greatest antiquity and the long-standing divergence of this branch from the common stem of the evolution of Caucasian strains. The genomes of strains of two other clusters also differ in a large number of individual SNPs, 32 and 36, respectively. One of them includes strains from the Pre-Sevan mountain, Zangezur-Karabakh mountain, and Pre-Araks low-mountain foci with the grouping within the cluster of three separate subclusters: Pre-Sevan (IIa), Zangezur-Karabakh (IIb), and Zangezur-Karabakh-Pre-Araks (IIc). Another one, the third cluster of the Caucasian subspecies, consists of strains from the northwestern part of the Caucasus highlands (Gyumri and Javakheti-Akhalkalaki foci). Using PCR with hybridization-fluorescent registration of results and whole genome sequencing, two clinical strains of Y. pestis were shown to belong to the Caucasian subtype, which confirms the ability of this subspecies to cause plague in humans. [ABSTRACT FROM AUTHOR]

The high-resolution mid-infrared spectrometer (HIRMES) under development for Stratospheric Observatory for Infrared Astronomy is an instrument operating in the 25-122 μm spectral range with a spectral resolution R = Δλ/λ ~ 100,000 and has two absorber-coupled transition edge sensor bolometric detector focal planes. We have developed novel NbTiN low-stress absorber coatings which have the required optical impedance across the HIRMES operating band. The low intrinsic stress of these coatings allow for a peak-to-valley corrugation amplitude < 5 μm of the 450 nm thick, 1.4 mm × 1.7 mm detector pixels. Furthermore, these coatings have a superconducting transition temperature ~ 10 K, which allows them to simultaneously serve as an absorber in the desired signal band and a rejection filter at long wavelengths. This attribute makes them especially attractive for ultrasensitive absorber-coupled bolometric detector applications, because it helps in controlling the optical loading from out-of-band radiation. We also discuss a novel method for integrating a wedged-reflective absorber termination to the detector array. [ABSTRACT FROM AUTHOR]

The high-resolution mid-infrared spectrometer (HIRMES) is a high resolving power (R ~ 100,000) instrument operating in the 25-122 μm spectral range and will fly on board the Stratospheric Observatory for Far-Infrared Astronomy in 2019. Central to HIRMES are its two transition edge sensor (TES) bolometric cameras, an 8 × 16 detector high-resolution array and a 64 × 16 detector low-resolution array. Both types of detectors consist of Mo/Au TES fabricated on leg-isolated Si membranes. Whereas the high-resolution detectors, with a noise equivalent power (NEP) ~ 1.5 × 10−18 W/rt (Hz), are fabricated on 0.45 μm Si substrates, the low-resolution detectors, with NEP ~ 1.0 × 10−17 W/rt (Hz), are fabricated on 1.40 μm Si. Here, we discuss the similarities and differences in the fabrication methodologies used to realize the two types of detectors. [ABSTRACT FROM AUTHOR]

Hyperbranched polyesters containing terminal p-toluenesulfonylamido and diethoxyphosphorylamido groups have been synthesized, and their complexes with copper(II) and cobalt(II) ions have been prepared. The thermal stability of the ligands and their metal complexes has been studied by differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

The high-resolution mid-infrared spectrometer instrument will fly onboard the National Aeronautics and Space Administration’s airborne stratospheric observatory for infrared astronomy in 2019. It will provide astronomers with a unique observing window (25-122 μm) for exploring the evolution of protoplanetary disks into young solar systems. There are two focal plane detector arrays for the instrument: a high-resolution (λ/Δλ=100,000) 8×16 detector array, with a target noise-equivalent power, NEP≤3aW/Hz, and a low-resolution (λ/Δλ=600-19,000) 16×64 detector array with a target NEP≤20aW/Hz. The detectors for both of these arrays are superconducting Mo/Au bilayer transition-edge sensor bolometers on suspended single-crystal silicon membranes. We present detector characterization results for both arrays, including measurements of thermal conductance in comparison with phonon transport models, and measurements of saturation power and noise. [ABSTRACT FROM AUTHOR]

Abstract: On the basis of the data of phylogeographical analysis, strains of Yersinia pestis are divided into a number of phylogenetic branches, and in accordance with the traditionally used subspecies classification in the CIS countries, they are divided into five subspecies. We conducted a study of the population structure and genetic characteristics of strains belonging to the phylogenetic branch 0.PE4 and its strains of the Altai subspecies—0.PE4a (Russia, Mongolia), the Hissar subspecies—0.PE4h (Tajikistan), the Talas population—0.PE4t (Kyrgyzstan), and the microtus population—0.PE4m (China). The uniformity of phenotypic and genetic characteristics of strains of the 0.PE4 branch has been established and the necessity of their association into one subspecies, the Central Asian (Y. pestis subsp. central asiatica), has been substantiated. The dendrogram demonstrates the presence of four separate subclusters corresponding to four populations: 0.PE4a (Altai strains), 0.PE4h (Hissar strains), 0.PE4t (Talas strains), and 0.PE4m (microtus strains) in the composition of the 0.PE4 cluster, which we propose to allocate to four biovars of the Central Asian subspecies: Altai, Hissar, Talas, and Microtus. A number of mutations specific only to 0.PE4 strains were detected. A DNA target was found and a method for differentiating the Central Asian subspecies (strains avirulent for humans) from other strains of Y. pestis by Real-Time PCR was developed. [ABSTRACT FROM AUTHOR]

A new water-soluble multidentate ligand based on a second-generation hyperbranched polyester containing 3-(morpholin-4-yl)propionate fragments in the terminal position has been synthesized, and its complex with copper(II) has been obtained. The degree of polyester functionalization with aminopropylmorpholine is 56%. [ABSTRACT FROM AUTHOR]

Abstract: Apart from strains of Vibrio cholerae biovar El Tor imported from cholera-endemic regions, causing outbreaks or sporadic cases of cholera, a significant number of different variants of nontoxigenic strains that can induce acute enteric infections are annually isolated from surface water bodies and human beings in the Russian Federation. We have carried out analysis of whole genomes that we sequenced (29) and obtained from the GenBank database (11), of 40 toxigenic and nontoxigenic strains isolated in cholera nonendemic (Russia, Ukraine, Turkmenistan, Georgia) and endemic (India, Bangladesh, Vietnam, and others) territories. It is established that they fall into three main groups which differ in the composition of mobile elements with pathogenicity and epidemicity genes, both from toxigenic isolates and among themselves. Nontoxigenic strains of the first group are deprived of all intact virulence prophages (CTXφ, RS1φ, TLCφ), pathogenicity (VPI-1, VPI-2) and pandemicity (VSP-I, VSP-II) islands, which testifies to their epidemic safety. The strains of the second group differ from the first one by the presence of the TLCφ prophage and two pathogenicity islands. It is demonstrated that this population of nontoxigenic strains, which is detected only in the Russian Federation and other cholera nonendemic regions, does not pose a potential epidemic hazard as was assumed earlier, despite the availability of tcpA-F genes in VPI-1. The lack of not only the CTXφ prophage but also VSP-I and VSP-II, which we revealed in these strains, eliminates the possibility of their reversion to epidemically hazardous ones. The strains of the third group have opulent similarity to toxigenic strains, being different in the absence of the CTXφ prophage only. It is this group of nontoxigenic strains, isolated only in cholera-endemic territories and capable of acquiring CTXφ through phage conversion, that is potentially epidemically hazardous. The results of whole genome SNP analysis of 58 different strains confirmed these data. We have also shown with the help of model animals (7- to 8-day-old rabbits) that nontoxigenic strains, irrespective of the structure of their genome, cannot cause typical cholera infection. The results provide insight into genomic diversity of nontoxigenic strains, as well as draw us nearer to an understanding of the mechanisms of reversion of their different variants into epidemically hazardous isolates. [ABSTRACT FROM AUTHOR]

The results of the construction of an avirulent strain of V. cholerae genovariant of the O1 serogroup of the El Tor biovar with efficient production of the cholera toxin (CT) B-subunit, which causes the formation of antitoxic immunity during cholera infection, are presented. In the beginning of the study, a modified P18899ΔCTXϕchr:TnphoA (KmRHly-) strain was obtained via nondirectional transposon mutagenesis on the basis of a nontoxigenic strain of a P18899ΔCTXϕHly+ genovariant. It lost the ability to produce thermolabile hemolysin, which is an additional toxin. The ctxB gene, which encodes biosynthesis of the CT B-subunit, was further introduced into cells of this strain. To accomplish this, the cointegrative recombinant plasmid pIEM3 was used. It was generated in the process of the fusion of a conjugative plasmid pIEM1 and a nonconjugative one, pCTΔ27, which is a derivative of pBR322 (which carries the cloned gene ctxB). Via restriction analysis, it was established that disjunction of a cointegrate occurred in vibrio cholera cells, followed by the preservation of a multicopy plasmid (pCTΔ27) only. As a result, avirulent clones of KmRTcR with a high production level (5-6 μg/mL) of secreted CT B-subunit were obtained, one of which (E99) was selected for further studies. Via real-time PCR, it was discovered that the expression of the ctxB plasmid gene in the cells of a designed strain of V. cholerae, E99, doesn't depend on the activity of the key regulatory gene toxT, which located on the chromosome. Efficient expression of the ctxB gene in E99 cells allows their use to obtain CT B-subunit in order to produce cholera immunobiological drugs. [ABSTRACT FROM AUTHOR]

Novel polydentate ligands on the basis of second- and third-generation hyperbranched polyesters containing terminal poly[3-(morpholin-4-yl)propionate] groups and their 6 : 1 and 13 : 1 polynuclear copper(II) complexes were synthesized. The degree of functionalization of the polyesters with morpholine increases in going from the second (56%) to third generation (68%). According to IR and electronic spectroscopy data, each coordination entity in the complexes is an isolated paramagnetic center of the formula CuNOSolv (Solv = HO, DMSO). [ABSTRACT FROM AUTHOR]

Comparative analysis of glucose fermentation in typical strains of V. cholerae biovar El Tor isolated in the Russian Federation in 1970-1990 and highly virulent strains of genovariants imported in 1993-2012 was carried out. It was demonstrated that glucose metabolism of V. cholerae biovar El Tor genovariants changed as a result of acquisition of classical CTX prophage (or only its ctxB gene) and a corresponding increase in virulence. A phenotypical manifestation of these changes is a lack of ability to grow on a minimal nutrient medium supplemented with 1% carbohydrate, as well as compromised capacity for acetoin fermentation in the course of the Voges-Proskauer test. Possible causes of the degraded glucose metabolism are associated with the presence of SNP in gene alsD that encodes acetolactate decarboxylase enzyme and is incorporated into als operon, which, in turn, is involved in acetoin generation, as well as with hyperexpression of regulatory protein AphA that controls acetoin biosynthesis. [ABSTRACT FROM AUTHOR]

This work represents the results of comparative analysis of the nucleotide sequences in the chromosomal region containing CTXφ prophage in isogenic toxigenic (Tox) and nontoxigenic (Tox) strains of Vibrio cholerae biovar El Tor. It is shown that spontaneous mutants which have identical Tox phenotype are formed either owing to the precise elimination of CTX prophage from the chromosome (deletion size is 6.9 kb) or owing to imprecise elimination with the additional loss of two other prophages (RS1φ and TLC), which are adjacent to CTX prophage (deletion size is 17.4 kb). It is revealed that, in the nontoxigenic mutants, CTX deletion initiates simultaneous change in several phenotypic properties, which are associated with virulence or biofilm formation, such as colonizing ability, HA/P production, VPS, and motility. For the first time, it is stated that the cause of the pleiotropic effect of the CTX deletion is a cascade decrease in the transcription levels of seven regulatory genes ( toxR, aphA, tcpP, tcpH, toxT, vpsT, vpsR) which control virulence and biofilm formation processes in the cholera agent. [ABSTRACT FROM AUTHOR]