Increase In Calcium Ion Concentration Research Articles

Mechanistic Investigation of Calcium Channel Regulation-Associated Genes in Pulmonary Arterial Hypertension and Signatures for Diagnosis.

Pulmonary arterial hypertension (PAH) is a severe cardiopulmonary disorder with complex causes. Calcium channel blockers have long been used in its treatment. Our study aimed to validate experimental results showing increased calcium ion concentration in PAH patients. We investigated the impact of genes related to calcium channel regulation on PAH development and developed an accurate diagnostic model. Clinical trial data from serum of 18 healthy individuals and 18 patients with PAH were retrospectively analyzed. Concentrations of calcium and potassium ions were determined and compared. Datasets were retrieved, selecting genes associated with calcium ion release. R packages processed the datasets, filtering 174 common genes, and conducting Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. Six hub genes were identified, and nomogram and logistic regression prediction models were constructed. Random forest filtered cross genes, and a diagnostic model was developed and validated using an artificial neural network. The 174 intersection genes related to calcium ions showed significant correlations with biological processes, cellular components, and molecular functions. Six key genes were obtained by constructing a protein-protein interaction network. A diagnostic model with high accuracy (> 90%) and diagnostic capability (AUC = 0.98) was established using a neural network algorithm. This study validated the experimental results, identified key genes associated with calcium ions, and developed a highly accurate diagnostic model using a neural network algorithm. These findings provide insights into the role of calcium release genes in PAH and demonstrate the potential of the diagnostic model for clinical application. However, due to limitations in sample size and a lack of prognosis data, the regulatory mechanisms of calcium ions in PAH patients and their impact on the clinical prognosis of PAH patients still need further exploration in the future.

Photoactivated 9-methylacridine destroys midgut tissues of Aedes aegypti larvae by targeting ROS-mediated apoptosis in the mitochondrial pathway of midgut cells

An aromatic ring-containing compound with a wide range of biological activities, 9-methylacridine (AD-9-Me) is a precursor for the synthesis of various drugs. However, its photoactivation properties and mechanism of damage as a photo activator against Aedes aegypti are unknown. The toxic effects of AD-9-Me on Aedes aegypti mosquitoes were determined under light and non-light conditions. The results showed that the toxicity of AD-9-Me to mosquito larvae was significantly higher than that of the dark treatment after 24 h of light exposure; AD-9-Me was mainly distributed in the midgut of larvae, after 24 h of treatment, it can cause an increase in calcium ion concentration, reactive oxygen species (ROS) eruption and ROS accumulation by blocking the ROS elimination pathway in midgut cells. This in turn caused an increase in protein carbonyl and malondialdehyde (MDA) content, a decrease in mitochondrial membrane potential (MMP), a disruption of the barrier function of midgut tissues, a significant decrease in midgut weight and chitin content, which induced the up-regulation of AeDronc, AeCaspase8 and AeCaspase7 genes, leading to apoptotic cell death. In this study, we confirmed that AD-9-Me has photoactivation activity and mainly acts on the midgut of mosquito larvae, which can generate a large amount of ROS in the cells of the midgut and induce apoptosis to occur, resulting in the disruption of the function of the tissues of mosquito larvae, accelerating the death and delaying the development of the mosquito larvae.

Morphofunctional traits and reactivity of the portal vein

Background: Portal vein is the most enigmatic vessel of our body because it regulates own contractile performances using a special pace-maker mechanism represented by cells of Cajal. The contribution of various metabolic mediators and natural vasotropic agents in the control of the portal blood circuit is much less studied compared to the arterial system in general and the hepatic system in particular. The studies designed on the structure, function, and reactivity of the portal vein in different preconditioning have brought some common but also distinct evidence of the arterial system. Nitric oxide production is higher partly due to reduced arginase expression, but muscular media is thinner. Periodic spontaneous contractions directed towards the liver gate are characteristic for portal vein (PV), and the longitudinal muscle fibers are considered to be responsible for this phenomenon. Spontaneous rhythmic oscillations of the cells of Cajal are triggered by increasing calcium ion concentration leading to their depolarization. PV constrictor effect of phenylephrine is dependent on the activity of receptors to ET-1. For PV is characterized the acetylcholine induced contraction either in vivo or in vitro, and this effect is thought to be dependent on ET-1. Conclusions: The establishment of main particularities of portal vein reactivity of action of different paracrine, endocrine, and hemodynamical stimuli represents an important tool for prediction of contractile disorders leading plausible to portal hypertension. Likewise, a well proven interplay between cholinergic and adrenergic stimulations and on the other hand between Ang II and ET-1 actions must be a support for pharmacological modulating of portal vein reactivity disorders.

Difference in the Osteoblastic Calcium Signaling Response Between Compression and Stretching Mechanical Stimuli

In orthodontics, various forms of mechanical stimulation induce opposing bone metabolism mechanisms. Bone resorption and bone formation occur in areas of compressive and tensile force action, respectively. The mechanism that causes such a difference in bone metabolism is still unclear. In this study, we investigated the difference in the osteoblastic calcium signaling response between compression and stretching mechanical stimuli. We applied two types of mechanical stimuli to osteoblast-like MC3T3-E1 cells: first microneedle direct indentation onto the cell as compression stimuli, and second stretching stimuli by using originally developed cell stretching MEMS device. Cells were treated with thapsigargin and calcium-free medium to investigate the source of the calcium ion. The results demonstrated variations in the osteoblastic calcium signaling response between the compression and stretching stimuli. The magnitude of an increase in the intracellular calcium ion concentration is much higher in the compression stimuli-applied cell group. Treatment of calcium-free medium nearly suppressed the calcium signaling response to both types of mechanical stimulation. Thapsigargin treatment induced an increase in the magnitude of calcium signaling response to the compression stimuli, while suppressed the slow and sustained increase in the calcium ion concentration in the stretching stimuli-applied cell group. These findings demonstrate the difference in the characteristics of osteoblastic calcium signaling response between compression and stretching mechanical stimuli.

Compensatory response of Hong Kong oysters to co-occurring stressors: Zinc oxide nanoparticles and low salinity exposure

Zinc Oxide nanoparticles (ZnO NPs), due to their ubiquitous use in industrial and consumer applications, present potential risks to marine ecosystems and biota, especially oysters. The physiological and immunological health of marine species is highly dependent on salinity levels. However, the combined impact of lowered salinity and exposure to ZnO NPs, particularly on key marine species like oysters, is an area that requires more research. Our study aimed to examine these concurrent stressors' impacts on phenotypic markers, gill and hepatopancreas physiological indices, and hemocyte immune parameters of Crassostrea hongkongensis. We subjected six oyster cohorts to varied ZnO NPs concentrations and salinity levels over 21 days. Our findings reveal that individual exposure to ZnO NPs or diminished salinity disrupts oyster physiology, impacting metabolism, antioxidant capacity, immune response, and energy distribution through distinct mechanisms. Remarkably, low salinity constituted a more significant threat than isolated ZnO NPs. However, when confronted with combined stressors, oysters exhibited a compensatory response, attenuating individual stressors' detrimental effects. This adaptation was characterised by reduced apoptosis rates, increased calcium ion concentration in mature hemocytes, and a restoration of conditioned indices, hepatopancreas alkaline phosphatase, and gill catalase activity to baseline levels. Principal Component Analysis and Integrated Biomarker Responses validated this compensatory phenomenon. Partial Least Squares Pathway Model analysis underscored these stressors' profound implications on oyster health, primarily driven by stressor exposure rather than mere zinc concentrations, despite acknowledging zinc's immunosuppressive impact on oyster immunity. Our research emphasises the importance of assessing multiple stressors' cumulative effects on aquatic species' ecological resilience, accentuating the need for comprehensive analyses incorporating functional specificity among diverse organs and immune components, including gill, hepatopancreas, and the critical hemocytes.

Experimental study on the calcium carbonate production rates and crystal size of EICP under multi-factor coupling

The production and microstructure of calcium carbonate are the fundamental indicators to evaluate the effectiveness of Enzyme-induced Carbonate Precipitation (EICP). Soybean urease is extracted, and the urease activity is controlled by the soybean powder concentration in this study. The urease reacts with the cementation solution with different concentrations of urea and calcium ions at different temperatures to determine the calcium carbonate production rates (RCC). The crystal sizes of calcium carbonate (SCC) are investigated by scanning electron microscopy (SEM) and image processing method. The RCC increase and subsequently decrease with increasing calcium ion concentration and peak at 0.75 M. A lower urea concentration is more favourable to the formation of CaCO3. Increased urease activity and temperature will lead to an increased RCC and SCC. Some crystals appear as capsules when the temperature goes up. The SCC decreases slightly with increasing calcium ion concentration under low urease activity and increases under high urease activity. The SCC increases first and subsequently decreases with increasing urea concentration under high urease activity, while the effect of urea concentration under low urease activity is not significant. XRD test results show that the calcium carbonate produced in this study is dominated by calcite crystals. The study provides additional data, a useful base to move forward toward a better understanding of the method of stabilization and its applications, for example, the treatment of different soils.

Effect of calcium ions concentration on the properties and microstructures of doubly induced sorghum arabinoxylan/soy protein isolate mixed gels

Sorghum bran arabinoxylan (AX) - soy protein isolate (SPI) mixed gel with multiple network structures and greater mechanical property was previously fabricated by duo-induction of peroxidase and calcium ions. The aim of current study was to achieve continuous improvement of the properties and microstructures of this dual-induced mixed gel by regulating the calcium ion concentrations, and to clarify the influence mechanism of calcium ions. The results showed that the addition of calcium ions (≤20 mM) caused the mixed gel network to regular and smooth, and effectively enhanced the mechanical strength. With the increase of calcium ion concentration (>20 mM), the gel network structure became disordered and rough, and the springiness, adhesiveness as well as chewiness decreased significantly. Fluorescence spectra, circular dichroism (CD) and chemical interaction forces analysis indicated that for the mixed gels formed by duo-induction, the low calcium ions concentration did not only change the secondary structure and molecular conformation of the protein, but also enhance its hydrophobic interactions, hydrogen bonds and disulfide bonds, leading to the formation of filamentous protein network. However, excessive calcium ions decreased the electrostatic interactions between polysaccharide and protein networks, weakened the cross-links between the networks, resulting in the formation of granular coarse gel network and the loss of gel springiness. Overall, appropriate calcium ion concentration had a positive effect on the microstructures and texture properties of the AX-SPI mixed gels. • Calcium ions had a significant effect on the gel properties of sorghum AX-SPI mixed gel. • Appropriate Ca 2+ concentration (≤20 mM) improved the hardness and springiness of AX-SPI mixed gel. • The addition of Ca 2+ enhanced hydrophobic interactions, hydrogen bonds and disulfide bonds except electrostatic interactions. • The SPI in mixed gel formed filamentous network at low Ca 2+ ,while formed granular network at high Ca 2+ . • Low Ca 2+ could promote the improvement of strength and microstructures of mixed gel.

Ethanol-Soluble Extract of Terminalia chebula Attenuates Paraquat-Induced Apoptosis in PC12 Cells

Parkinson’s disease is the second most common neurodegenerative disease after Alzheimer’s disease. This study was aimed at investigating the neuroprotective mechanisms of the ethyl acetate fraction of Terminalia chebula ethanol-soluble extract using PC12 cells treated with paraquat as a model system. The ethyl acetate fraction of T. chebula ethanol-soluble extract was prepared using 95% ethanol and ethyl acetate as described in our previous study. The neuroprotective potential of the ethyl acetate fraction of T. chebula ethanol-soluble extract was analyzed by evaluating the intracellular reactive oxygen species and calcium levels, apoptosis, caspase-3 and α-synuclein activities, as well as Bcl-2 and Bax expressions. The ethyl acetate fraction of T. chebula ethanol-soluble extract exhibited neuroprotective effects against paraquat-induced apoptosis in PC12 cells at concentrations ranging from 0.4 μg/mL to 0.6 μg/mL. The various neuroprotective mechanisms identified for the extract included reduction in reactive oxygen species levels; inhibition of increased calcium ion concentration; increased Bcl-2 expression; reduced Bax, caspase-3 and α-synuclein expression; and reduced nuclear shrinkage. This study elucidates the various mechanisms underlying the neuroprotective effects of the ethyl acetate fraction of T. chebula ethanol-soluble extract that may further aid the Parkinson’s disease pharmacological application of T. chebula.

Sanguinarine induces apoptosis in Eimeria tenella sporozoites via the generation of reactive oxygen species

Eimeria tenella (E. tenella) is the most pathogenic genus in Eimeria and can lead to a huge number of deaths of chickens, causing significant economic losses in the poultry industry worldwide. As a natural alkaloid, sanguinarine has many medicinal effects; to a certain extent, it can replace antibiotics and has good application prospects in veterinary medicine. To evaluate the effect of sanguinarine on sporozoites of E.tenella, we used flow cytometry and immunofluorescence staining to detect reactive oxygen species (ROS), mitochondrial membrane potential (MMP), calcium ion (Ca2+), and caspase-3 activation in E.tenella sporozoites treated with different concentrations of sanguinarine. The results of flow cytometry showed that sanguinarine could inhibit the invasion of sporozoites of E.tenella in vitro (P < 0.05) and increase the reactive oxygen species and calcium ions in the sporozoites (P < 0.05). The results of immunofluorescence staining showed that sanguinarine could decrease the mitochondrial membrane potential of sporozoites. Our analysis suggests that sanguinarine can induce apoptosis of E. tenella sporozoites through reactive oxygen species-mediated reduction of the mitochondrial membrane potential and an increase in calcium ion concentration. It follows that sanguinarine is likely to be a novel type of anticoccidiosis drug with good research and clinical application prospects.

TET1 mediated male reproductive toxicity induced by Bisphenol A through Catsper-Ca2+ signaling pathway

Bisphenol A (BPA) exposure has many adverse effects on the reproductive system in animals and humans. Ten-eleven translocation 1 (TET1) is closely related to a variety of biological processes through regulating the dynamic balance of DNA demethylation and methylation. However, the role and mechanism of TET1 during BPA induced reproductive toxicity are largely unknown. In this study, mouse spermatogonia cell line GC-2 was treated with BPA in the final concentration of 0, 20, 40 and 80 μM for 72 h. The cell model of differential TET1 gene expression was established to explore the role and mechanism. We found that the growth rate of GC-2 cells, and the intracellular calcium level decreased significantly with the increase of BPA dose, while TET1 and Catsper1-4 expression level decrease with a dose-dependent relationship. Furthermore, TET1 overexpression promoted the proliferation of GC-2 cell, the increase of calcium ion concentration, and the expression level of Catsper1-4, while knockdown of TET1 leads to the opposite results. Mechanistically, TET1 expression promoted the hydroxymethylation of Catsper1-4 and reduced their methylation level. In addition, the expression level of Catsper1-4 was positively correlated with TET1 gene expression level in semen samples of the population. Our study revealed for the first time that TET1 gene regulates the expression of related molecules in the Catsper calcium signal pathway through its hydroxymethylation modification to affect the calcium level, thereby participating in the process of BPA induced damage. These results indicated that TET1 gene may be a potential biomarker of BPA induced male reproductive toxicity.

Effect of calcium chloride on heat-induced Mesona chinensis polysaccharide-whey protein isolation gels: Gel properties and interactions

Salt ions play an important role in the quality structure of food and sensory properties. This study aims to investigate the effects of different concentrations of calcium chloride (0–0.012 mol/L) on the gel properties and interactions of heat-induced Mesona chinensis polysaccharide (MCP)-whey protein isolate (WPI) mixed gels. It was found that the apparent viscosity decreases gradually with the increase of calcium ion concentration, especially when the calcium ion concentration reaches 0.012 mol/L, the apparent viscosity is the lowest. The water holding capacity of the mixed gel decreased from 86.25% to 32.05% and the network structure of the gel became looser, which was consistent with low-field magnetometry results and the variation of microstructure. In the in vitro digestion experiments, the addition of 0.003 mol/L calcium chloride was effective in reducing the degradation of the gel. The results of chemical bonding analysis indicated that hydrogen bond and hydrophobic interactions were the key forces that promoting gel formation and maintaining the gels network structure. This study showed that calcium ions could change the contribution of hydrogen bonding, disulfide bonds, and hydrophobic interactions to the gelation process.

Extracellular Vesicles Generated Using Bioreactors and their Therapeutic Effect on the Acute Kidney Injury Model.

Extracellular vesicles (EVs) are nano-sized vesicles secreted by cells, having beneficial effects for various types of regenerative processes. Although EVs have shown promising effects as therapeutic agents, these effects are difficult to research due to the limitations of EV production. In this study, an EV production method based on a flat-plate bioreactor is introduced. The bioreactor produces approximately seven times more mesenchymal stem cell-derived EVs than static culture conditions. The mechanism underlying the increased production of EVs in a flat-plate bioreactor and its application to acute kidney injury is investigated. This study describes the mechanism of EV production by demonstrating the link between EV biogenesis and increased calcium ion concentration under flow conditions. EVs secreted by cells cultured in the bioreactor have therapeutic efficacy in terms of improving kidney damage, resulting in tissue regeneration in a cisplatin-induced acute kidney injury model. This method will help overcome the limitations of EV production, and the analysis of the application of EVs will increase their reliability as well as the understanding of the use of bioreactor-derived EVs as therapeutic agents.

Characterization of a clonal human periodontal ligament stem cell line exposed to methacrylate resin-, bioactive glass-, or silicon-based root canal sealers.

The aim of this study was to characterize a clonal human periodontal ligament (PDL) stem cell line (line 2-23 cells) cultured with root canal sealers based on methacrylate resin (SuperBond sealer; SB), bioactive glass (Nishika Canal Sealer BG; BG), or silicon (GuttaFlow 2; GF). The sealers were set in rubber molds to form sealer discs. Line 2-23 cells were cultured with or without the discs for 3days. The cell viability was evaluated by direct cell counting and MTT assay. Inflammation-, PDL-, collagen-, and cell cycle-related gene expression was investigated by real-time RT-PCR. Collagen production was analyzed by Picro Sirius Red staining. Calcium ion concentration in the culture was measured by a QuantiChrom calcium assay kit. Line 2-23 cells survived when cultured with GF discs, but decreased cell viability was observed with SB and BG discs. The expression of inflammation-related genes was higher in cells cultured with SB discs, and expression of PDL-related genes was lower in cells exposed to SB and BG discs. These discs also down-regulated collagen production in line 2-23 cells. BG discs increased calcium ion concentration in the culture medium. Cells exposed to GF discs exhibited the same inflammation-, PDL-, collagen-, and cell cycle-related gene expression and collagen production as untreated cells. These results suggested that the characteristics of line 2-23 cells cultured with GF discs was highly resemble to untreated cells throughout the 3days of the culture model.

Adsorption behavior of anionic surfactants to silica surfaces in the presence of calcium ion and polystyrene sulfonate

Adsorption behavior of surfactants to rock surfaces is an important issue in oil recovery, especially in the process of surfactant flooding. The surfactant loss through adsorption to rock surfaces makes such process economically less feasible. Here, we investigated the adsorption behavior of anionic surfactants (alcohol alkoxy sulfate, AAS) onto silica with quartz crystal microbalance with dissipation monitoring. The results demonstrated that the surfactant adsorption followed the Langmuir adsorption isotherm. Up to solution pH 10, surfactant adsorption slightly increased with increasing pH. The higher pH leads to more anionic surface sites for binding with an anionic surfactant with the help of a calcium cation bridging. The amount of anionic surfactant binding also increases with increasing calcium ion concentration up to 50 mM. It was found that sodium ions were able to exchange calcium ions near the silica surface, which would reduce the affinity for surfactant adsorption. The effect of the polyanion polystyrene sulfonate (PSS) on the anionic AAS adsorption was investigated to learn the possible competitive adsorptions. Indeed, this was found. Upon addition of 50 ppm PSS to a 0.05 wt% AAS containing solution, the adsorption of AAS was reduced by about 85 %. The obtained results show the interplay of different interacting species affecting the overall degree of anionic surfactant adsorption to silica surfaces. Optimal tuning of the process conditions according to these results will contribute to a more efficient use of anionic surfactants in enhanced oil recovery.

Effect of calcium ions on the adsorption and lubrication behavior of salivary proteins on human tooth enamel surface

The aim of this study is to investigate the effect of calcium ions on the adsorption and lubrication behavior of salivary proteins on human tooth enamel. Human whole saliva was collected from healthy donors. Three testing groups were calcium ion-enhanced saliva samples with an increased ion concentration of 1 mmol/L, 5 mmol/L, and 10 mmol/L, respectively. Normal saliva was used as a control. The adsorption behavior was tested using quartz crystal microbalance with dissipation (QCM-D), while the mechanical properties and lubricating behavior of salivary pellicle were examined by nano-indentation/scratch technique. Results show that the increased calcium ion concentration in the saliva weakens the electrostatic interaction between the salivary proteins and enamel surface, but causes increases in the thickness and viscoelasticity of the salivary pellicle formed on enamel surface. Therefore, the load-bearing and anti-shear capacity of the pellicle is improved, and then the anti-wear and friction-reducing effect of the pellicle is enhanced. In sum, the addition of calcium ion in saliva can contribute to the formation of the salivary pellicle with enhanced lubrication performance and help to alleviate the excessive tooth wear of xerostomia patients.

The Ability of Biodentine™ of Guided Tissue Remineralization (GTR): Analysis Using SEM, EDX and TEM

Objective: To analyze the Biodentine™ capability in guided tissue remineralization. Material and Methods: Four premolar with two cavities per tooth of 3 mm depth were demineralized with EDTA 17% in shaking incubator at 37°C temperature. After 7 days, the sample were washed with aquabidest then were soaked in 20 ml NaCl 1 M (pH 7.0) at 25°C temperature for 8 hours. The samples were divided into two groups: G1: The control group (cavity directly restored with composite resin); G2: Biodentine™group (cavity with Biodentine™as a base then restored with composite resin). All samples were stored in shaking incubator under PBS solution at 37°C temperature. SEM, EDX and TEM analysis were performed on the 7 th and 14 th day. Results: The 14 th day Biodentine group had the best SEM remineralization feature with irregular dentine tubular features covered by density of mass. In the EDX analysis, the concentration of calcium ion of the Biodentine group was higher than the control group on the 7 th day analysis (Biodentin™ 10.2167 and control 1.9667) and on the 14 th day analysis (Biodentine™ 29.833 and Control 22.080). The Biodentine™ group and control group of the 7th and 14th day experienced significant increases in calcium ion concentration while the concentration of phosphate ion in the Biodentine™ and control group had a much lower value of calcium either on the 7 th or 14 th day. The TEM analysis of Biodentine™ group showed more intrafibrillar remineralization than the control group. The feature of intrafibrillar dentin remineralization is analyzed by looking at the density of black dots in collagen. Conclusion: Biodentine™ is able to trigger the process of remineralization by guided tissue remineralization.

Degradation in vitro and in vivo of β-TCP/MCPM-based premixed calcium phosphate cement

Premixed calcium phosphate cements (CPCs) have been developed to shorten the surgical time of conventional CPCs. However, there is lack of investigation on degradation behavior of premixed CPCs in vitro and in vivo. In this study, the premixed CPCs are prepared by mixing glycerol or polyethylene glycol (PEG) with the CPC power (β-tricalcium phosphate (β-TCP) and monocalcium phosphate monohydrate (MCPM)), and their degradation performances including the microstructure, chemical composition and mechanical properties are systematically evaluated both in vitro and in vivo (subcutaneous implantations in rabbits). When the premixed CPCs aged in PBS or FBS, results show weight loss of the specimens, decreased pH value and increased calcium ion concentration of aging media. Meanwhile, the setting products convert from dicalcium phosphate dihydrate (DCPD) to dicalcium phosphate anhydrous (DCPA), and no hydroxyapatite deposit. The specimen size and the molecular weight of non-aqueous solvent can modulate the setting product of premixed CPCs. For the larger specimens, DCPA is the main setting product, for the smaller ones, the composite contained DCPD and DCPA. With the decrease of the molecular weight of the non-aqueous solvent PEG, the setting product change from both DCPD and DCPA to DCPA due to the quicker exchange rate of PEG with water. After a period of subcutaneous implantation, the surface of the grafts obviously disintegrated with the formation of porous structures, but their internal morphology do not obviously change.

Plants signal danger through nervelike process

When a caterpillar, or some other pesky herbivore, nibbles on a leaf, the plant sends danger signals to its farthest fronds to activate the plant’s defense mechanisms, such as producing noxious compounds to chase off the pest or turning on pathways to heal damaged tissues. Now a research team led by Masatsugu Toyota at Saitama University reports that this signaling happens through a nervelike process involving glutamate, which is a neurotransmitter in mammals (Science 2018, DOI: 10.1126/science.aat7744). The team either cut the stems of or enticed caterpillars to munch on Arabidopsis plants engineered to express a protein sensor that fluoresces when it binds calcium ions. The plant’s defense mechanisms are triggered in part by increases in calcium ion concentration. Using fluorescent microscopy, the team detected spikes in calcium ion levels immediately at the sites of damage and two minutes later in distant leaves. The timing was too fast to be

Role of coexistence of negative and positive membrane surface charges in electrostatic effect for salt rejection by nanofiltration

Electrostatic effect is a primary mechanism for nanofiltration (NF) in rejecting mineral ions in water. In this study, efforts were devoted to understand the change of membrane surface charges by pH-titrating synthesized poly(piperazine-amide) material in the presence of NaCl or CaCl2 of different concentrations. It revealed that the membrane surface charges were resulted from dissociation and protonation of functional groups when in contact with NaCl solution, and additionally from specific complexation of calcium ions by acidic groups when in contact with CaCl2 solution. Viewing the membrane with a uniform surface potential could not well explain the rejection behavior for CaCl2-containing solutions. We proposed to treat the membrane surface as a mixed collection of positively and negatively charged regions, with these regions able to reject ions relatively separately. Increasing calcium ion concentration in the feed water could increase the proportion of positively charged regions. The enhanced shielding on positively-charged regions could reduce the rejection of calcium ions while that on negatively-charged regions could increase the rejection. This study could act to initiate further studies on the roles and importance of the coexistence of negative and positive charges at membrane surface in electrostatic effect on salt rejection.

Cationic liposomes suppress intracellular calcium ion concentration increase via inhibition of PI3 kinase pathway in mast cells

Cationic liposomes are commonly used as vectors to effectively introduce foreign genes (antisense DNA, plasmid DNA, siRNA, etc.) into target cells. Cationic liposomes are also known to affect cellular immunocompetences such as the mast cell function in allergic reactions. In particular, we previously showed that the cationic liposomes bound to the mast cell surface suppress the degranulation induced by cross-linking of high affinity IgE receptors in a time- and dose-dependent manner. This suppression is mediated by impairment of the sustained level of intracellular Ca2+ concentration ([Ca2+]i) via inhibition of store-operated Ca2+ entry (SOCE). Here we study the mechanism underlying an impaired [Ca2+]i increase by cationic liposomes in mast cells. We show that cationic liposomes inhibit the phosphorylation of Akt and PI3 kinases but not Syk and LAT. As a consequence, SOCE is suppressed but Ca2+ release from endoplasmic reticulum (ER) is not. Cationic liposomes inhibit the formation of STIM1 puncta, which is essential to SOCE by interacting with Orai1 following the Ca2+ concentration decrease in the ER. These data suggest that cationic liposomes suppress SOCE by inhibiting the phosphorylation of PI3 and Akt kinases in mast cells.