Hydrobionts of a freshwater oil-polluted northern lake: bioaccumulation of heavy metals in fish and the rate of ecosystem recovery

The response of phytoplankton, zooplankton, benthic and fish community structure to one of the biggest oil spill in history of Komi Republic (north-west part of Russia) was investigated using data from a long-term survey off the polluted lake. The characteristics of aquatic freshwater communities observed in the study area 10, 11 and 22 years after the spill (1994) were compared to find out the rate of natural recovery of the ecosystem after oil decontamination of bottom sediments. The concentrations of fifteen trace metals (Al, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Pb, U, Bi, Th) were analyzed in the tissues (muscle) of three fish species. The concentrations of Al (3-309 mg/kg), Cr (0,1-3,71 mg/kg), Fe (8,6-317 mg/kg), and Cu (0,09-99 mg/kg) in fishes from polluted lake resulted in most cases higher than reference thresholds. Quantitative and qualitative indicators of aquatic invertebrates from polluted lake reach those one of unpolluted lake but do not fully recover 22 years after the spill, despite that oil concentration in water column and in bottom sediments was lower than reference tresholds. We conclude that natural recovery rate of aquatic freshwater ecosystems in northern regions after oil pollution is extremely low. The purification of water and bottom sediments of oil-polluted northern water bodies is necessary for stimulation of ecosystem restoration

Model of ionic currents through microtubule nanopores and the lumen

It has been suggested that microtubules and other cytoskeletal filaments may act as electrical transmission lines. An electrical circuit model of the microtubule is constructed incorporating features of its cylindrical structure with nanopores in its walls. This model is used to study how ionic conductance along the lumen is affected by flux through the nanopores when an external potential is applied across its two ends. Based on the results of Brownian dynamics simulations, the nanopores were found to have asymmetric inner and outer conductances, manifested as nonlinear IV curves. Our simulations indicate that a combination of this asymmetry and an internal voltage source arising from the motion of the C-terminal tails causes a net current to be pumped across the microtubule wall and propagate down the microtubule through the lumen. This effect is demonstrated to enhance and add directly to the longitudinal current through the lumen resulting from an external voltage source, and could be significant in amplifying low-intensity endogenous currents within the cellular environment or as a nano-bioelectronic device.Comment: 43 pages, 6 figures, revised versio

Investigation of the Lipopolysaccharide Cluster Structure in the Genomes of <i>Vibrio cholerae</i> Rough Variants

Determination of Vibrio cholerae affiliation to one or another serogroup may meet some difficulties in cases of atypical agglutination with diagnostic cholera sera. The study of genetic determinants that allows for identifying a serogroup is a relevant task in monitoring of surface water body contamination with cholera vibrios.The aim of the work was to compare the structural organization (quantitative and qualitative gene composition) of LPS clusters in V. cholerae rough variants.Materials and methods. We used Illumina MiSeq for the whole genome sequencing; SPAdes software (version 3.11.1) for de novo assembly; and blastn (v. 2.5.0) for gene searching. GeneMarkS software was deployed for annotation of the genes incorporated in the clusters; nucmer – for searching homologous sites. Visualization of O-LPS clusters was carried out by means of SnapGene Viewer.Results and discussion. Strains of V. cholerae rough variants had diverse gene clusters responsible for O-antigen biosynthesis. We have identified three types of O-LPS clusters with different size and number of genes. Unique DNA sites, common to the whole group of V. cholerae rough variants, have not been detected. Two genes present in all rough strains have been defined, but they are not unique for this group of strains and can be found in representatives of other serogroups. For two types of clusters, a region containing the IS‑element, common with V. cholerae O1, has been revealed

Epidemiological Situation on the Tick-Borne Viral Encephalitis in the Russian Federation in 2009-2011 and Prognosis for 2012

Analysis of the epidemiological situation on the tick-borne viral encephalitis in the territory of the Russian Federation with due consideration to weekly epidemiological monitoring data (2009-2011), conducted by Rospotrebnadzor organizations in the corresponding constituent entities, testifies of the fact that continuous decrease in morbidity, characteristic of the early XXI century, has given way to a slight increase within the past three years. Given that there are no spring or early-summer weather anomalies or forest fires, morbidity rates among the population of the Russian Federation in 2012 can tend to exceed 2011 rates. Comprehensive set of measures applied for the disease control and prevention in the majority of endemic territories is quite effective in view of averting sharp upturn of morbidity rates, but nevertheless is not sufficient in view of the suppression of epidemiological situation

Assessment of the Variation Range of Agglutinability in <i>Vibrio cholerae</i> Strains Isolated in the Course of Monitoring Studies

The aim of the study was to retrospectively analyze the range of variability of antigenic properties and genotypic characteristics of Vibrio cholerae R-variant strains atypical in terms of agglutinability.Materials and methods. 169 strains of V. cholerae R-variant with atypical agglutinability have been studied using the “AmpliSens® Vibrio cholerae-FL” test-system. The determination of O1 antigen was carried out using the “Ig-V. cholerae О1/О139 – ELISA/dot-ELISA” reagent kit.Results and discussion. A retrospective analysis of the complex of phenoand genotypic characteristics of strains isolated from surface water bodies in the territories of three former Soviet republics and 13 constituent entities of the Russian Federation in the course of 30-year monitoring and identified upon isolation as nontoxigenic V. cholerae R-variant strains has been performed. Upon re-identification, it was found that the strains belong to both epidemically dangerous (3.0 %) and non-dangerous strains (97.0 %). The range of variability was expressed in their distribution into three groups and consisted in retaining of agglutinability only with cholera RO serum in the first group (34.5 % of strains); the loss of this trait, but the acquisition of the ability to agglutinate in different combinations with O1, Ogawa or Inaba sera – in the second (16.7 %); and also in the loss of agglutinability with all diagnostic cholera sera – in the third (48.8 %). The presence of the wbeT gene in the compared V. cholerae classical R-variant strain does not exclude the presence of the genomic region for O1 antigen biosynthesis in other R-strains, possibly in a modified form, which can be clarified in further molecular-genetic studies. Alternatively, such strains are likely to be attributed to V. cholerae nonO1/nonO139. Strains of V. cholerae R-variant with different amounts of surface antigen (optical density range – from 0.088±0.002 to 1.226±0.003) have been identified. The data obtained can be used for monitoring of cholera in laboratories of regional and federal levels

Epidemiological Situation on Tick-Borne Viral Encephalitis in the Territory of the Russian Federation in 2012 and Prognosis for 2013

Analyzed are the epidemiological situation and preventive measures against tick-borne encephalitis in the territory of the Russian Federation in 2012. Short-term forecast for 2013 is made based on the population morbidity rate in the federal districts of Russia in 2007–2012

Direct knock-on of desolvated ions governs strict ion selectivity in K+ channels

The seeming contradiction that K+ channels conduct K+ ions at maximal throughput rates while not permeating slightly smaller Na+ ions has perplexed scientists for decades. Although numerous models have addressed selective permeation in K+ channels, the combination of conduction efficiency and ion selectivity has not yet been linked through a unified functional model. Here, we investigate the mechanism of ion selectivity through atomistic simulations totalling more than 400 μs in length, which include over 7,000 permeation events. Together with free-energy calculations, our simulations show that both rapid permeation of K+ and ion selectivity are ultimately based on a single principle: the direct knock-on of completely desolvated ions in the channels' selectivity filter. Herein, the strong interactions between multiple 'naked' ions in the four filter binding sites give rise to a natural exclusion of any competing ions. Our results are in excellent agreement with experimental selectivity data, measured ion interaction energies and recent two-dimensional infrared spectra of filter ion configurations

Organizational and Functional Reassignment of a Scientific Plague Control Institution of the Rospotrebnadzor under Conditions of Coronavirus Infection Pandemic

The aim of the work was to summarize the experience of the Rostov-on-Don Research Anti-Plague Institute in the organizational and functional response aimed at ensuring the implementation of a complex of on-going and scheduled anti-epidemic (preventive) measures at different territorial levels in the context of COVID-19 pandemic. Stage-wise reassignment of scientific and operational subdivisions of the facility was carried out in a timely manner in a flexible mode for a prompt response to the challenges that arose from community transmission of the new coronavirus infection in the territory of the Russian Federation. It allowed an effective distribution of the forces and assets without damage for specialized functioning in the main areas of scientific and practical activities. Realized was an effective interdepartmental interaction with territorial scientific and practical institutions of the Rospotrebnadzor and specialized medical organizations. Practical, methodological and advisory assistance was provided to personnel of specialized medical institutions within the framework of conversing in-patient facilities into hospitals for the treatment of patients with COVID-19. Priority research to study the level of the humoral and cellular immune response to SARS-CoV-2 among the population of the Rostov Region, the etiological spectrum of the causative agents of community-acquired pneumonia associated with COVID-19, full genome sequencing of SARS-CoV-2 isolates was carried out. Specialists of the task forces reinforced human resources of individual laboratory facilities in Moscow city, the Republic of Crimea and the Rostov Region. Complex objective of effective functioning has been implemented: in an operational mode – participation in anti-epidemic (preventive) measures in the face of changes in the dynamics and intensity of the epidemic manifestations of new coronavirus infection; in scheduled mode – the implementation of activities in the main areas of the scientific work of the organization

Adhesion of alumina surfaces through confined water layers containing various molecules

When two surfaces confine water layers between them at the nanoscale, the behaviour of these confined water molecules can deviate significantly from the behaviour of bulk water and it could reflect on the adhesion of such surfaces. Thus, the aim of this study is to assess the role of confined water layers on the adhesion of hydrophilic surfaces and how sensitive this adhesion is to the presence of contaminants. Our methodology used under water AFM force measurements with an alumina sputtered sphere-tipped cantilever and a flat alumina single crystal, then added fractions of ethanol, dimethylformamide, formamide, trimethylamine, and trehalose to water, as contaminants. Such solutions were designed to illuminate the influences of dielectric constant, molecular size, refractive index and number of hydrogen bonds from donors and acceptors of solutes to water. Apart from very dilute solutions of dimethylformamide, all solutions decreased the ability of confined water to give adhesion of the alumina surfaces. The predicted theoretical contribution of van der Waals and electrostatic forces was not observed when the contaminants distorted the way water organizes itself in confinement. The conclusion was that adhesion was sensitive mostly to hydrogen bonding network within water layers confined by the hydrophilic alumina surfaces