Changes In NaCl Concentration Research Articles

Neuronal sensorimotor integration guiding salt concentration navigation in Caenorhabditis elegans

Animals navigate their environment by manipulating their movements and adjusting their trajectory which requires a sophisticated integration of sensory data with their current motor status. Here, we utilize the nematode Caenorhabditis elegans to explore the neural mechanisms of processing the sensory and motor information for navigation. We developed a microfluidic device which allows animals to freely move their heads while receiving temporal NaCl stimuli. We found that C. elegans regulates neck bending direction in response to temporal NaCl concentration changes in a way which is consistent with a C. elegans' navigational strategy which regulates traveling direction toward preferred NaCl concentrations. Our analysis also revealed that the activity of a neck motor neuron is significantly correlated with neck bending and activated by the decrease in NaCl concentration in a phase-dependent manner. By combining the analysis of behavioral and neural response to NaCl stimuli and optogenetic perturbation experiments, we revealed that NaCl decrease during ventral bending activates the neck motor neuron which counteracts ipsilateral bending. Simulations further suggest that this phase-dependent response of neck motor neurons can facilitate curving toward preferred salt concentrations.

Influence of seawater concentration on alkali-silica reaction of seawater sea-sand concrete: Mimicking through NaCl solution and recycled glass aggregate

Seawater sea-sand concrete (SSC) is one environment-friendly and promising construction material. Nevertheless, limited research shed favorable light on alkali-silica reaction (ASR) of SSC. This work provided a novel insight regarding the fast test method that (i) the recycled glass aggregate (RGA) was used for fast assessing the effect of seawater concentration on ASR, reusing its characteristic resource; (ii) the NaCl solutions with different concentrations were used to mimic different salinities of sea waters; and (iii) a modified curing method was adopted. The results showed that the NaCl solution could be used for assessing ASR risk of SSC instead of seawater. The specimens mixed with twice and above the sodium concentration of seawater would exhibit ASR expansion, strength reduction, coarsening of nanopore distribution, and the cracks on the macro and micro levels. However, the change of NaCl concentration scarcely affected the composition and content of hydration products. Additionally, with increasing the mixing Na+ concentration, the ASR crack would firstly appear in the interface between the cement paste layer and the glass layer, and then developed in the internal zone of RGA matrix with different hardness, elastic modulus, and Si contents based on the destroyed degree.

Natural Ventilation and Air Purification for Effective Removal of Airborne Virus in Classrooms with Heater Operation.

Mass COVID-19 infection cases in indoor spaces have been continuously reported since its global outbreak, generating increasing public interest in reducing the spread of the virus. This study considered a situation in which an infected individual continuously releases the virus into the air in a classroom, simulated by continuous injection of NaCl particles ≤ 5 μm, with heater operation during winter. The effects of applying natural ventilation and operating one or two air purifiers on the removal of virus-containing aerosols were experimentally compared and analyzed based on the spatiotemporal changes in NaCl concentration within the classroom. When a heater was operated with all windows shut, operating one and two air purifiers reduced the amount of the aerosol in indoor air by approximately 50 and 60%, respectively, compared to the case with no air purifier. Additionally, when the heater was operated with one or two air purifiers under natural ventilation, the amount of virus-containing aerosol in the air was reduced by 86–88% compared to the case with neither natural ventilation nor air purifier. Because natural ventilation significantly varies with weather conditions and particulate matter concentrations, combining natural ventilation with air purifiers in classrooms during winter needs to be adjusted appropriately.

Sensing and Responding to Hypersaline Conditions and the HOG Signal Transduction Pathway in Fungi Isolated from Hypersaline Environments: Hortaea werneckii and Wallemia ichthyophaga.

Sensing and responding to changes in NaCl concentration in hypersaline environments is vital for cell survival. In this paper, we identified and characterized key components of the high-osmolarity glycerol (HOG) signal transduction pathway, which is crucial in sensing hypersaline conditions in the extremely halotolerant black yeast Hortaea werneckii and in the obligate halophilic fungus Wallemia ichthyophaga. Both organisms were isolated from solar salterns, their predominating ecological niche. The identified components included homologous proteins of both branches involved in sensing high osmolarity (SHO1 and SLN1) and the homologues of mitogen-activated protein kinase module (MAPKKK Ste11, MAPKK Pbs2, and MAPK Hog1). Functional complementation of the identified gene products in S. cerevisiae mutant strains revealed some of their functions. Structural protein analysis demonstrated important structural differences in the HOG pathway components between halotolerant/halophilic fungi isolated from solar salterns, salt-sensitive S. cerevisiae, the extremely salt-tolerant H. werneckii, and halophilic W. ichthyophaga. Known and novel gene targets of MAP kinase Hog1 were uncovered particularly in halotolerant H. werneckii. Molecular studies of many salt-responsive proteins confirm unique and novel mechanisms of adaptation to changes in salt concentration.

Исследование устойчивости Lactobacillus sakei к осмотическому стрессу

Introduction. The development of new technologies of bacterial cultures for fish products is an important area of re-search. Sodium chloride (NaCl) has an inhibitory effect on most microorganisms and is often used in fish industry. The present research objective was to study the effect of NaCl on the growth of lactic acid bacteria of the species Lactoba-cillus sakei.
 Study objects and methods. The research featured strains of lactic acid bacteria L. sakei (L. sakei LSK-45 and L. sakei DSM 20017). The bacteria were cultivated in a semi-liquid MRS medium supplemented with sodium chloride at vari-ous concentrations. The optical density (OD) of the medium and the viable cell counts served as indicators of bacterial growth. The morphology of bacterial cells was studied by microscopic examination of Gram-stained bacteria.
 Results and discussion. Both L. sakei strains proved tolerant to NaCl concentrations up to 6% as proved by the high density of the cell population – 109 CFU/cm3. When NaCl concentration reached 10%, L. sakei LSK-45 demonstrated the highest resistance to osmotic stress. At the end of cultivation, the population density dropped to 108 CFU/cm3, and the survival rate was 92%. The number of viable cells of L. sakei DSM 20017 decreased to 106 CFU/cm3, and the sur-vival rate reached 62%. The high resistance of L. sakei LSK-45 to osmotic stress was caused by cell cohesion, which increased with the growing NaCl concentration and was regulated by the quorum sensing system.
 Conclusion. L. sakei showed a flexible response to the changes in NaCl concentration. L. sakei LSK-45 strain had the highest resistance to osmotic stress.

Production and characterisation of a biosurfactant based on Acinetobacter sp. V2 and its potential use for environmental applications

ABSTRACT Maximum biosurfactant production was achieved in an optimised process containing pH 8 and 30°C, with waste coconut oil and ammonium sulphate at carbon-to-nitrogen ratio of 1:7. The structural composition of Acinetobacter sp. V2 biosurfactant was polymeric, consisting of a protein complex and a fatty acid. This biosurfactant exhibited stability to different pH and temperature conditions. The emulsifying property was affected by changes in NaCl concentration. The V2 biosurfactant was effective in removing heavy metals present in acid mine drainage effluents and contaminated vegetables.

Effect of wet-curing on physical properties and proteins of cured ham

AbstractConsuming enough protein is a very important part of a balanced and healthy diet. Complete proteins are those in which all essential amino acids are present. In meat products, like hams, many different reactions occur during ageing and storage. For example, the production of free amino acids or the production of biogenic amines is formed by decarboxylation. In this study, the presence of these amino acids and biogenic amines, as well as the quality properties of cured hams during curing and ageing, were investigated.The meat samples were immersed into 100 g L−1 NaCl brine. The curing took 20 days, followed by smoking and ageing for 35 days (12 °C, 75% RH). The wet-cured ham samples were analysed for changes in NaCl concentration (at 3 parts: surface, core, bottom layer). Moreover, color, water activity, denaturation temperature and enthalpy (Differential Scanning Calorimetry), free amino acids (FAAs) and biogenic amines (BAs) were also evaluated.

Stability influence factors and mechanism of produced emulsion from CO2 flooding

CO2 flooding has been widely applied for enhanced oil recovery (EOR) in recent years, while the difficulty in demulsification of the produced fluid has become an urgent problem due to the specific physical and chemical properties of CO2 flooding process. In this study, the crude oil from Block Hei-59 by CO2 flooding was used to prepare simulated produced emulsions and the influence of CO2 pressure, temperature, salinity, pH and solid particles on the stability of emulsions are investigated. The results indicated that the stability of simulated emulsions gradually increased with CO2 pressure but decreased with the increase of temperature, while the change of NaCl concentration and pH had little effects on the stability of emulsions. Moreover, the solid particles had great influences on the stability of the emulsion, and the emulsion prepared by the particles initially dispersed in the oil phase was more stable than in water. This study can provide a theoretical basis for the future dehydration and demulsification treatment of produced fluids from the formation developed by CO2 flooding.

Heavy Metal Extractions from NaCl Brines to Pseudoprotic Ionic Liquids

In liquid–liquid extractions, the aqueous phase from which heavy metal ions are extracted often contains a mixture of salt ions (brine). These additional salt ions may have an effect on the efficiency and selectivity of the extraction of a specific heavy metal ion and may cause a shift in extraction mechanism when the organic phase is an ionic liquid. This has been demonstrated in this study for the extraction of Co, Ni, or Zn chloride by three pseudoprotic ionic liquids (PPILs) in the absence or presence of NaCl up to 4 times the concentration in seawater. In most cases, the extraction efficiency was increased by the presence of NaCl. This increase resulted from a shift in equilibrium referred to as the van’t Hoff–le Chatelier effect. In all cases, also, sodium ions were extracted, but at low efficiencies. An increase in NaCl presence in the brine leads to a slightly higher sodium extraction efficiency, which can also be contributed to the van’t Hoff–le Chatelier effect. Zn ions were transferred to the PPILs by neutral extraction, but only without NaCl in the brine. In all other cases, the transfer of the metal ions occurred with increasing anion exchange between the chloride ions and the trihexylammonium octanoate and trioctylammonium benzoate anions if more NaCl was present. In the case of extraction of Co or Ni ions with trioctylammonium salicylate, a shift in mechanism from anion into cation exchange was observed with a change in NaCl concentration.

Is it feasible to replace freshwater by seawater in hydrothermal liquefaction of biomass for biocrude production?

Crude bio-oil production through hydrothermal liquefaction (HTL) of biomass requires a tremendous amount of water. Current operations commonly use freshwater as the processing medium that is already scarce across the globe. Replacing freshwater by seawater holds promise, however has not been explored yet. In this study, four types of biomass with largely different biochemical compositions were chosen as representative feedstocks, including microalgae (Chlorella sp.), marine macroalgae (red seaweed), food processing waste (spent coffee grounds) and lignocellulosic waste (sawdust). Microwave-assisted HTL of each feedstock was conducted under varying NaCl concentrations, 0 wt%, 1.5 wt% and 3 wt%, representing freshwater, brackish water and seawater respectively. Change in NaCl concentration was not influential for HTL of Chlorella sp., red seaweed and spent coffee grounds in terms of biocrude yield and quality. However, in the HTL of sawdust (containing more fibers than the other three feedstocks), a much lower biocrude yield (7.9 wt%, daf) was obtained in seawater than in freshwater (27.1 wt% daf), presumably due to the condensation of intermediates generated from decomposed carbohydrate and lignin in the presence of NaCl. This assumption was further verified by a computational simulation based upon Density Functional Theory, indicating that the condensation of phenolics-aldehydes was kinetically favored in the presence of NaCl.

Salt-triggered Active Plasmonic Systems Based on the Assembly/Disassembly of Gold Nanorods in a DNA Brush Layer on a Solid Substrate

In this study, we demonstrate that the plasmonic properties of gold nanorods (GNRs) electrostatically adsorbed on a DNA brush substrate are reversibly controlled by changes in NaCl concentration. T...

Rotatable microfluidic device for simultaneous study of bilateral chemosensory neurons in Caenorhabditis elegans

The nematode Caenorhabditis elegans is a leading model system in genetics, development and neurobiology; its transparent body and small size make it particularly suitable for fluorescent imaging of cells and neurons within microfluidic setups. Simultaneously recording activity in bilaterally symmetric cells has proved difficult in C. elegans because the worm enters the chip and is then immobilised when it is lying on one side of the body. We developed a side-view rotatable microfluidic device that allows us to image a pair of bilateral neurons in a single focal plane of an epi-fluorescence microscope. We demonstrated the utility of the device by recording the responses of immobilised worms to controlled stimuli, focusing on the responses of two classes of head sensory neurons to changes in NaCl concentration. The results indicate that responses of ASE left and right and ASH left and right sensory neurons are stochastic. Simultaneous recordings of ASH left and right neurons tend to synchronise, pointing to a role of gap junctional connectivity. The anatomy of the C. elegans nerve ring makes this microfluidic approach ideally suited for the study of spatially extended pairs of neurons or larger neuronal circuits that lie within a limited depth of field.

Using a Robust and Sensitive GFP-Based cGMP Sensor for Real-Time Imaging in Intact Caenorhabditis elegans.

cGMP plays a role in sensory signaling and plasticity by regulating ion channels, phosphodiesterases, and kinases. Studies that primarily used genetic and biochemical tools suggest that cGMP is spatiotemporally regulated in multiple sensory modalities. FRET- and GFP-based cGMP sensors were developed to visualize cGMP in primary cell culture and Caenorhabditis elegans to corroborate these findings. While a FRET-based sensor has been used in an intact animal to visualize cGMP, the requirement of a multiple emission system limits its ability to be used on its own as well as with other fluorophores. Here, we demonstrate that a C. elegans codon-optimized version of the cpEGFP-based cGMP sensor FlincG3 can be used to visualize rapidly changing cGMP levels in living, behaving C. elegans. We coexpressed FlincG3 with the blue-light-activated guanylyl cyclases BeCyclOp and bPGC in body wall muscles, and found that the rate of change in FlincG3 fluorescence correlated with the rate of cGMP production by each cyclase. Furthermore, we show that FlincG3 responds to cultivation temperature, NaCl concentration changes, and sodium dodecyl sulfate in the sensory neurons AFD, ASEL/R, and PHB, respectively. Intriguingly, FlincG3 fluorescence in ASEL and ASER decreased in response to a NaCl concentration upstep and downstep, respectively, which is opposite in sign to the coexpressed calcium sensor jRGECO1a and previously published calcium recordings. These results illustrate that FlincG3 can be used to report rapidly changing cGMP levels in an intact animal, and that the reporter can potentially reveal unexpected spatiotemporal landscapes of cGMP in response to stimuli.

An Excitatory/Inhibitory Switch From Asymmetric Sensory Neurons Defines Postsynaptic Tuning for a Rapid Response to NaCl in Caenorhabditis elegans.

The neural networks that regulate animal behaviors are encoded in terms of neuronal excitation and inhibition at the synapse. However, how the temporal activity of neural circuits is dynamically and precisely characterized by each signaling interaction via excitatory or inhibitory synapses, and how both synaptic patterns are organized to achieve fine regulation of circuit activities is unclear. Here, we show that in Caenorhabditis elegans, the excitatory/inhibitory switch from asymmetric sensory neurons (ASEL/R) following changes in NaCl concentration is required for a rapid and fine response in postsynaptic interneurons (AIBs). We found that glutamate released by the ASEL neuron inhibits AIBs via a glutamate-gated chloride channel localized at the distal region of AIB neurites. Conversely, glutamate released by the ASER neuron activates AIBs via an AMPA-type ionotropic receptor and a G-protein-coupled metabotropic glutamate receptor. Interestingly, these excitatory receptors are mainly distributed at the proximal regions of the neurite. Our results suggest that these convergent synaptic patterns can tune and regulate the proper behavioral response to environmental changes in NaCl.

Assessing Protein Dynamics on Low-Complexity Single-Stranded DNA Curtains.

Single-stranded DNA (ssDNA) is a critical intermediate in all DNA transactions. Because ssDNA is more flexible than double-stranded (ds) DNA, interactions with ssDNA-binding proteins (SSBs) may significantly compact or elongate the ssDNA molecule. Here, we develop and characterize low-complexity ssDNA curtains, a high-throughput single-molecule assay to simultaneously monitor protein binding and correlated ssDNA length changes on supported lipid bilayers. Low-complexity ssDNA is generated via rolling circle replication of short synthetic oligonucleotides, permitting control over the sequence composition and secondary structure-forming propensity. One end of the ssDNA is functionalized with a biotin, while the second is fluorescently labeled to track the overall DNA length. Arrays of ssDNA molecules are organized at microfabricated barriers for high-throughput single-molecule imaging. Using this assay, we demonstrate that E. coli SSB drastically and reversibly compacts ssDNA templates upon changes in NaCl concentration. We also examine the interactions between a phosphomimetic RPA and ssDNA. Our results indicate that RPA-ssDNA interactions are not significantly altered by these modifications. We anticipate that low-complexity ssDNA curtains will be broadly useful for single-molecule studies of ssDNA-binding proteins involved in DNA replication, transcription, and repair.

Hempseed meal protein isolates prepared by different isolation techniques. Part II. gelation properties at different ionic strengths

The effect of isolation technique and sodium chloride level (0, 50, 300 mM, at pH 7.0) on gelation of hemp protein isolates was investigated. The aqueous dispersions (30% w/w) prepared from micelle (salt extracted) protein isolate (HMI) behaved more as concentrated liquid-like dispersions, while the dispersions prepared from the alkali extracted/isoelectric precipitated protein isolate (HPI) had a paste-like consistency. Although changes in NaCl concentration did not have a pronounced impact on the rheological properties and microstructure of HPI dispersions, an increase in NaCl concentration led to HMI protein isolate aggregation. On heating, both HMI and HPI formed gels as indicated by dynamic oscillatory rheological measurements. Confocal micrographs have shown that the HPI gels had a granular, particulate structure, while the HMI gels had cellular-like structure formed from thin strands. In the case of HMI gels, 300 mM NaCI concentration caused intensive protein-protein interactions, which resulted in the formation of an aggregate structure with larger pore sizes in comparison to HMI gels prepared from low salt (50 mM NaCl) or without salt aqueous dispersions. On the contrary, NaCl addition slightly affected the HPI gels microstructure in terms of preservation of protein globular structure.

Effect of sodium chloride on oxidative stress biomarkers of the freshwater bivalve Anodonta cygnea

For the first time a study was conducted of the effects of the change in the concentration of sodium chloride in water on the biomarkers of oxidative stress (enzymes: catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST), and the levels of reduced glutathione (GSH), and a marker of peroxidation lipids (LPO) – malonic dialdehyde (MDA)) in the gills of the freshwater mollusc Anodonta cygnea. Adult specimens of A. cygnea of both sexes with a shell length of 70–100 mm were selected for the study, a total of 36 individuals. The molluscs were collected in one of the bays on the southwestern coast of the Volga reaches of the Rybinsk Reservoir (reservoir of the cascade of the upper Volga). The molluscs were kept in the laboratory in aquariums with river water and sand collected from the place of the molluscs' collection. During the experiment, a solution of NaCl 3 g/l in river water was introduced into the container with molluscs. Samples of molluscs’ tissues were taken before application of the saline solution, 40 and 120 min after changing the salt concentration to 3 g/l, and 20 and 60 min after changing the NaCl solution to river water. The change in the concentration of NaCl in water (0–3 g/l) did not affect the content of water-soluble protein in the gills of molluscs during short-term exposure. The change in NaCl concentration in water caused the intensification of LPO processes in the gills of A. cygnea. The change in the activity of the enzymes of the antioxidant system and the increase in the concentration of GSH in A. cygnea gills, indicates their involvement in protecting freshwater molluscs from NaCl-induced oxidative stress. The change in the functioning of the glutathione system may be a compensatory mechanism for changing the NaCl concentration in water. Such biomarkers of oxidative stress as malonic dialdehyde and enzymes of the antioxidant system are sensitive indicators of changes in NaCl concentration in water in freshwater bivalve molluscs, for example A. cygnea.

An Improved Method for Establishing Accurate Water Potential Levels at Different Temperatures in Growth Media.

NaCl, KCl, or PEG (polyethylene glycol)-amended potato dextrose broth (PDB), and potato dextrose agar (PDA) are essential for pure culture studies of water stress on fungi. Direct information on the actual water potential (WP) of this salt-amended PDB and PDA is lacking. Much fungal research in the past calculated WP of these salt-amended growth media by adding the WP of their constituents taken from individual salt dilution studies. But the WP of any complex solution will be modified by the level of synergism between its solutes. This study presents evidence of change in NaCl concentration due to synergism for attaining the same level of WP in NaCl solution, and NaCl amended PDB and PDA. The relation between WP and temperature and WP and salt concentration is also modified depending on the number of solutes in a growth medium. The WP of PEG-amended PDB increases with rising temperature, while that of NaCl/KCl amended PDB and PDA decreases with the increase of temperature. These results can be useful for doing pure culture studies on the biology and modeling the growth of air, water, and soil-borne fungi important in the food and agriculture industry and in terrestrial and aquatic ecosystems.

A Computational Model Based on Multi-Regional Calcium Imaging Represents the Spatio-Temporal Dynamics in a Caenorhabditis elegans Sensory Neuron

Due to the huge number of neuronal cells in the brain and their complex circuit formation, computer simulation of neuronal activity is indispensable to understanding whole brain dynamics. Recently, various computational models have been developed based on whole-brain calcium imaging data. However, these analyses monitor only the activity of neuronal cell bodies and treat the cells as point unit. This point-neuron model is inexpensive in computational costs, but the model is unrealistically simplistic at representing intact neural activities in the brain. Here, we describe a novel three-unit Ordinary Differential Equation (ODE) model based on the neuronal responses derived from a Caenorhabditis elegans salt-sensing neuron. We recorded calcium responses in three regions of the ASER neuron using a simple downstep of NaCl concentration. Our simple ODE model generated from a single recording can adequately reproduce and predict the temporal responses of each part of the neuron to various types of NaCl concentration changes. Our strategy which combines a simple recording data and an ODE mathematical model may be extended to realistically understand whole brain dynamics by computational simulation.

Sodium Chloride Diffusion in Low-Acid Foods during Thermal Processing and Storage.

This study aimed at modeling sodium chloride (NaCl) diffusion in foods during thermal processing using analytical and numerical solutions and at investigating the changes in NaCl concentrations during storage after processing. Potato, radish, and salmon samples in 1% or 3% NaCl solutions were heated at 90, 105, or 121°C for 5 to 240 min to simulate pasteurization and sterilization. Selected samples were stored at 4 or 22°C for up to 28 d. Radish had the largest equilibrium NaCl concentrations and equilibrium distribution coefficients, but smallest effective diffusion coefficients, indicating that a greater amount of NaCl diffused into the radish at a slower rate. Effective diffusion coefficients determined using the analytical solution ranged from 0.2 × 10(-8) to 2.6 × 10(-8) m²/s. Numerical and analytical solutions showed good agreement with experimental data, with average coefficients of determination for samples in 1% NaCl at 121°C of 0.98 and 0.95, respectively. During storage, food samples equilibrated to a similar NaCl concentration regardless of the thermal processing severity. The results suggest that sensory evaluation of multiphase (solid and liquid) products should occur at least 14 d after processing to allow enough time for the salt to equilibrate within the product.