Hydrotropism mechanisms and their interplay with gravitropism.

Plants partly optimize their water recruitment from the growth medium by directing root growth toward a moisture source, a phenomenon termed hydrotropism. The default mechanism of downward growth, termed gravitropism, often functions to counteract hydrotropism when the water-potential gradient deviates from the gravity vector. This review addresses the identity of the root sites in which hydrotropism-regulating factors function to attenuate gravitropism and the interplay between these various factors. In this context, the function of hormones, including auxin, abscisic acid, and cytokinins, as well as secondary messengers, calcium ions, and reactive oxygen species in the conflict between these two opposing tropisms is discussed. We have assembled the available data on the effects of various chemicals and genetic backgrounds on both gravitropism and hydrotropism, to provide an up-to-date perspective on the interactions that dictate the orientation of root tip growth. We specify the relevant open questions for future research. Broadening our understanding of root mechanisms of water recruitment holds great potential for providing advanced approaches and technologies that can improve crop plant performance under less-than-optimal conditions, in light of predicted frequent and prolonged drought periods due to global climate change.

ATP2B4 is an essential gene for epidermal growth factor-induced macropinocytosis in A431 cells.

Macropinocytosis (MPC) is a large-scale endocytosis pathway that involves actin-dependent membrane ruffle formation and subsequent ruffle closure to generate macropinosomes for the uptake of fluid-phase cargos. MPC is categorized into two types: constitutive and stimuli-induced. Constitutive MPC in macrophages relies on extracellular Ca2+ sensing by a calcium-sensing receptor. However, the link between stimuli-induced MPC and Ca2+ remains unclear. Here, we find that both intracellular and extracellular Ca2+ are required for epidermal growth factor (EGF)-induced MPC in A431 human epidermoid carcinoma cells. Through investigation of mammalian homologs of coelomocyte uptake defective (CUP) genes, we identify ATP2B4, encoding for a Ca2+ pump called the plasma membrane calcium ATPase 4 (PMCA4), as a Ca2+-related regulator of EGF-induced MPC. Knockout (KO) of ATP2B4, as well as depletion of extracellular/intracellular Ca2+, inhibited ruffle closure and macropinosome formation, without affecting ruffle formation. We demonstrate the importance of PMCA4 activity itself, independent of interactions with other proteins via its C-terminus known as a PDZ domain-binding motif. Additionally, we show that ATP2B4-KO reduces EGF-stimulated Ca2+ oscillation during MPC. Our findings suggest that EGF-induced MPC requires ATP2B4-dependent Ca2+ dynamics.

Amlodipine inhibits Synaptotagmin-4's oncogenic activity on gastric cancer proliferation by targeting calcium signaling.

BACKGROUND: Gastric cancer (GC) remains a leading cause of cancer mortality globally. Synaptotagmin-4 (SYT4), a calcium-sensing synaptic vesicle protein, has been implicated in the oncogenesis of diverse malignancies. PURPOSE: This study delineates the role of SYT4 in modulating clinical outcomes and biological behaviors in GC. METHODS: We evaluated SYT4 expression in GC specimens using bioinformatics analyses and immunohistochemistry. Functional assays included CCK8 proliferation tests, apoptosis assays via flow cytometry, confocal calcium imaging, and xenograft models. Western blotting elucidated MAPK pathway involvement. Additionally, we investigated the impact of the calcium channel blocker amlodipine on cellular dynamics and MAPK pathway activity. RESULTS: SYT4 was higher in GC tissues, and the elevated SYT4 was significantly correlated with adverse prognosis. Both univariate and multivariate analyses confirmed SYT4 as an independent prognostic indicator for GC. Functionally, SYT4 promoted tumorigenesis by fostering cellular proliferation, inhibiting apoptosis, and enhancing intracellular Ca2+ influx, predominantly via MAPK pathway activation. Amlodipine pre-treatment attenuated SYT4-driven cell growth and potentiated apoptosis, corroborated by in vivo xenograft assessments. These effects were attributed to MAPK pathway suppression by amlodipine. CONCLUSION: SYT4 emerges as a potential prognostic biomarker and a pro-oncogenic mediator in GC through a Ca2+-dependent MAPK mechanism. Amlodipine demonstrates significant antitumor effects against SYT4-driven GC, positing its therapeutic promise. This study underscores the imperative of targeting calcium signaling in GC treatment strategies.

Supramolecular Engineering of Ti3C2Tx MXene -Perylene Diimide Hybrid Electrodes for the Pseudocapacitive Electrochemical Storage of Calcium Ions.

The rare combination of metallic conductivity and surface redox activity enables 2D MXenes as versatile charge storage hosts for the design of high-rate electrochemical energy storage devices. However, high charge density metal ions including but not limited to Ca+2 and Mg+2 pose challenges such as sluggish solid-state diffusion and also inhibiting the charge transfer across electrode-electrolyte interfaces. In this work, free-standing hybrid electrode architectures based on 2D titanium carbide-cationic perylene diimide (Ti3C2Tx@cPDI) via supramolecular self-assembly are developed. Secondary bonding interactions such as dipole-dipole and hydrogen bonding between Ti3C2Tx and cPDI are investigated by zeta potential and Fourier-transformed infrared (FTIR) spectroscopy . Ti3C2Tx@cPDI free-standing electrodes show typical volumetric capacitance up to 260 F cm-3 in Mg2+ and Ca2+ aqueous electrolytes at charging times scales from 3 minutes to a few seconds. Three-dimensional (3D) Bode maps are constructed to understand the charge storage dynamics of Ti3C2Tx@cPDI hybrid electrode in an aqueous Ca-ion electrolyte. ,Pseudocapacitance is solely contributed by the nanoscale distribution of redox-active cPDI supramolecular polymers across 2D Ti3C2Tx. This study opens avenues for the design of a wide variety of MXene@redox active organic charge hosts for high-rate pseudocapacitive energy storage devices.

ROS and Ca2+ signaling involved in important lipid changes of Chlorella pyrenoidosa under nitrogen stress conditions.

MAIN CONCLUSION: Nitrogen stress altered important lipid parameters and related genes in Chlorella pyrenoidosa via ROS and Ca2+ signaling. The mutual interference between ROS and Ca2+ signaling was also uncovered. The changed mechanisms of lipid parameters (especially lipid classes and unsaturation of fatty acids) in microalgae are not completely well known under nitrogen stress. Therefore, Chlorella pyrenoidosa was exposed to 0, 0.5, 1 and 1.5 g L-1 NaNO3 for 4 days. Then, the physiological and biochemical changes were measured. It was shown that the total lipid contents, neutral lipid ratios as well as their related genes (accD and DGAT) increased obviously while the polar lipid ratios, degrees of unsaturation as well as their related genes (PGP and desC) decreased significantly in nitrogen stress groups. The obvious correlations supported that gene expressions should be the necessary pathways to regulate the lipid changes in C. pyrenoidosa under nitrogen stress. The changes in ROS and Ca2+ signaling as well as their significant correlations with corresponding genes and lipid parameters were analyzed. The results suggested that ROS and Ca2+ may regulate these gene expressions and lipid changes in C. pyrenoidosa under nitrogen stress conditions. This was verified by the subordinate tests with an ROS inhibitor and calcium reagents. It also uncovered the clues of mutual interference between ROS and Ca2+ signaling. To summarize, this study revealed the signaling pathways of important lipid changes in microalgae under N stress.

Calcineurin B-like protein ZmCBL8-1 promotes salt stress resistance in Arabidopsis.

MAIN CONCLUSION: ZmCBL8-1 enhances salt stress tolerance in maize by improving the antioxidant system to neutralize ROS homeostasis and inducing Na+/H+ antiporter gene expressions of leaves. Calcineurin B-like proteins (CBLs) as plant-specific calcium sensors have been explored for their roles in the regulation of abiotic stress tolerance. Further, the functional variations in ZmCBL8, encoding a component of the salt overly sensitive pathway, conferred the salt stress tolerance in maize. ZmCBL8-1 is a transcript of ZmCBL8 found in maize, but its function in the salt stress response is still unclear. The present study aimed to characterize the protein ZmCBL8-1 that was determined to be composed of 194 amino acids (aa) with three conserved EF hands responsible for binding Ca2+. However, a 20-aa fragment was found to be missing from its C-terminus relative to another transcript of ZmCBL8. Results indicated that it harbored a dual-lipid modification motif MGCXXS at its N-terminus and was located on the cell membrane. The accumulation of ZmCBL8-1 transcripts was high in the roots but relatively lower in the leaves of maize under normal condition. In contrast, its expression was significantly decreased in the roots, while increased in the leaves under NaCl treatment. The overexpression of ZmCBL8-1 resulted in higher salt stress resistance of transgenic Arabidopsis in a Ca2+-dependent manner relative to that of the wild type (WT). In ZmCBL8-1-overexpressing plants exposed to NaCl, the contents of malondialdehyde and hydrogen peroxide were decreased in comparison with those in the WT, and the expression of key genes involved in the antioxidant defense system and Na+/H+ antiporter were upregulated. These results suggested that ZmCBL8-1 played a positive role in the response of leaves to salt stress by inducing the expression of Na+/H+ antiporter genes and enhancing the antioxidant system to neutralize the accumulation of reactive oxygen species. These observations further indicate that ZmCBL8-1 confers salt stress tolerance, suggesting that transcriptional regulation of the ZmCBL8 gene is important for salt tolerance.

Modelling spatio-temporal interactions between second messengers Ca 2 + and cAMP in a pancreatic ß -cell.

Calcium serves as a widespread second messenger in almost every human and animal cell. The regulation of various cellular processes, such as transcriptional control and the kinetics of membrane channels, is significantly influenced by intracellular calcium ions (Ca 2 + ), and linkages between Ca 2 + and other second messengers should activate signaling networks. The passage of ions across the cell membrane regulates Ca 2 + levels in pancreatic ß -cells and requires the coordinated interaction of various ion transport mechanisms and organelles. The signaling of Ca 2 + in ß -cells and its interactions with the intracellular dynamics of cyclic adenosine monophosphate (cAMP) is poorly understood. Therefore, the current investigation proposes a mathematical model to illustrate the spatiotemporal dynamical interaction between Ca 2 + and cAMP. In order to construct a one-dimensional mathematical model, the fundamental initial and boundary conditions derived from the physiological characteristics of the ß -cell are incorporated. The numerical results were obtained by MATLAB simulations using the finite element method and the Crank-Nicolson method. The current study aims to offer an update on regulation between Ca 2 + and cAMP signaling circuits, with a focus on interactions that occur in localized areas of the ß -cell. The model gives the individual effect of each parameter on the regulation of Ca 2 + and cAMP profiles in a ß -cell. Evidently, impairments in the regulation of messenger pathways contribute to the pathological conditions, as demonstrated by the results obtained.

In vivo cytosolic H2O2 changes and Ca2+ homeostasis in mouse skeletal muscle.

Hydrogen peroxide (H2O2) and calcium ions (Ca2+) are functional regulators of skeletal muscle contraction and metabolism. Although H2O2 is one of the activators of the type-1 ryanodine receptor (RyR1) in the Ca2+ release channel, the interdependence between H2O2 and Ca2+ dynamics remains unclear. This study tested the following hypotheses using an in vivo model of mouse tibialis anterior (TA) skeletal muscle. 1) Under resting conditions, elevated cytosolic H2O2 concentration ([H2O2]cyto) leads to a concentration-dependent increase in cytosolic Ca2+ concentration ([Ca2+]cyto) through its effect on RyR1; and 2) in hypoxia (cardiac arrest) and muscle contractions (electrical stimulation), increased [H2O2]cyto induces Ca2+ accumulation. Cytosolic H2O2 (HyPer7) and Ca2+ (Fura-2) dynamics were resolved by TA bioimaging in young C57BL/6J male mice under four conditions: 1) elevated exogenous H2O2; 2) cardiac arrest; 3) twitch (1 Hz, 60 s) contractions; and 4) tetanic (30 s) contractions. Exogenous H2O2 (0.1-100 mM) induced a concentration-dependent increase in [H2O2]cyto (+55% at 0.1 mM; +280% at 100 mM) and an increase in [Ca2+]cyto (+3% at 1.0 mM; +8% at 10 mM). This increase in [Ca2+]cyto was inhibited by pharmacological inhibition of RyR1 by dantrolene. Cardiac arrest-induced hypoxia increased [H2O2]cyto (+33%) and [Ca2+]cyto (+20%) 50 min postcardiac arrest. Compared with the exogenous 1.0 mM H2O2 condition, [H2O2]cyto after tetanic muscle contractions rose less than one-tenth as much, whereas [Ca2+]cyto was 4.7-fold higher. In conclusion, substantial increases in [H2O2]cyto levels evoke only modest Ca2+ accumulation via their effect on the sarcoplasmic reticulum RyR1. On the other hand, contrary to hypoxia secondary to cardiac arrest, increases in [H2O2]cyto from muscle contractions are small, indicating that H2O2 generation is unlikely to be a primary factor driving the significant Ca2+ accumulation after, especially tetanic, muscle contractions.NEW & NOTEWORTHY We developed an in vivo mouse myocyte H2O2 imaging model during exogenous H2O2 loading, ischemic hypoxia induced by cardiac arrest, and muscle contractions. In this study, the interrelationship between cytosolic H2O2 levels and Ca2+ homeostasis during muscle contraction and hypoxic conditions was revealed. These results contribute to the elucidation of the mechanisms of muscle fatigue and exercise adaptation.

Distinct regulation of two flagella by calcium during chemotaxis of male gametes in the brown alga Mutimo cylindricus (Cutleriaceae, Tilopteridales).

Brown algal male gametes show chemotaxis to the sex pheromone that is released from female gametes. The chemotactic behavior of the male gametes is controlled by the changes in the beating of two flagella known as the anterior and posterior flagellum. Our previous study using Mutimo cylindricus showed that the sex pheromone induced an increment in both the deflection angle of the anterior flagellum and sustained unilateral bend of the posterior flagellum, but the mechanisms regulating these two flagellar waveforms were not fully revealed. In this study, we analyzed the changes in swimming path and flagellar waveforms with a high-speed recording system under different calcium conditions. The extracellular Ca2+ concentration at 10-3 M caused an increment in the deflection angle of the anterior flagellum only when ionomycin was absent. No sustained unilateral bend of the posterior flagellum was induced either in the absence or presence of ionomycin in extracellular Ca2+ concentrations below 10-2 M. Real-time Ca2+ imaging revealed that there is a spot near the basal part of anterior flagellum showing higher Ca2+ than in the other parts of the cell. The intensity of the spot slightly decreased when male gametes were treated with the sex pheromone. These results suggest that Ca2+-dependent changes in the anterior and posterior flagellum are regulated by distinct mechanisms and that the increase in the anterior flagellar deflection angle and sustained unilateral bend of the posterior flagellum may not be primarily induced by the Ca2+ concentration.

Involvement of nucleus accumbens SERCA2b in methamphetamine-induced conditioned place preference.

Methamphetamine (METH) is a highly addictive psycho-stimulant that induces addictive behaviour by stimulating increased dopamine release in the nucleus accumbens (NAc). The sarco/endoplasmic reticulum calcium ion transport ATPases (SERCA or ATP2A) is a calcium ion (Ca2+) pump in the endoplasmic reticulum (ER) membrane. SERCA2b is a SERCA subtype mainly distributed in the central nervous system. This study used conditioned place preference (CPP), a translational drug reward model, to observe the effects of SERCA and SERCA2b on METH-CPP in mice. Result suggested that the activity of SERCA was significantly decreased in NAc after METH-CPP. Intraperitoneal SERCA agonist CDN1163 injection or bilateral CDN1163 microinjection in the NAc inhibited METH-CPP formation. SERCA2b overexpression by the Adeno-associated virus can reduce the DA release of NAc and inhibit METH-CPP formation. Although microinjection of SERCA inhibitor thapsigargin in the bilateral NAc did not significantly aggravate METH-CPP, interference with SERCA2b expression in NAc by adeno-associated virus increased DA release and promoted METH-CPP formation. METH reduced the SERCA ability to transport Ca2+ into the ER in SHSY5Y cells in vitro, which was reversed by CDN1163. This study revealed that METH dysregulates intracellular calcium balance by downregulating SERCA2b function, increasing DA release in NAc and inducing METH-CPP formation. Drugs that target SERCA2b may have the potential to treat METH addiction.

The involvement of calcium in the toxic effect of 4-methylethcathinone on SH-SY5Y cells.

Neurotoxicity induced by psychoactive substances is often accompanied by an imbalance of intracellular calcium ions. It is unclear whether calcium ions play a role in the toxicity induced by psychoactive substances. In the present study, we aimed to evaluate the occurrence of calcium dysregulation and its contribution to cytotoxicity in human neurotypic SH-SY5Y cells challenged with a recently developed psychoactive substance 4-methylethcathinone (4-MEC). An increase in the intracellular calcium was detected by inductively coupled plasma atomic emission spectrometry and Fluo-3 AM dye in SH-SY5Y cells after being treated with 4-MEC. The increase of intracellular Ca2+ level mediated G0/G1 cell cycle arrest and ROS/endoplasmic reticulum stress-autophagy signaling pathways to achieve the toxicity of 4-MEC. In particular, N-acetyl-L-cysteine, a classical antioxidant, was found to be a potential treatment for 4-MEC-induced toxicity. Taken together, our results demonstrate that an increase in intracellular calcium content is one of the mechanisms of 4-MEC-induced toxicity. This study provides a molecular basis for the toxicity mechanism and therapeutic intervention of psychoactive substances.

Structural and energetic analysis of metastable intermediate states in the E1P-E2P transition of Ca2+-ATPase.

Sarcoplasmic reticulum (SR) Ca2+-ATPase transports two Ca2+ ions from the cytoplasm to the SR lumen against a large concentration gradient. X-ray crystallography has revealed the atomic structures of the protein before and after the dissociation of Ca2+, while biochemical studies have suggested the existence of intermediate states in the transition between E1P⋅ADP⋅2Ca2+ and E2P. Here, we explore the pathway and free energy profile of the transition using atomistic molecular dynamics simulations with the mean-force string method and umbrella sampling. The simulations suggest that a series of structural changes accompany the ordered dissociation of ADP, the A-domain rotation, and the rearrangement of the transmembrane (TM) helices. The luminal gate then opens to release Ca2+ ions toward the SR lumen. Intermediate structures on the pathway are stabilized by transient sidechain interactions between the A- and P-domains. Lipid molecules between TM helices play a key role in the stabilization. Free energy profiles of the transition assuming different protonation states suggest rapid exchanges between Ca2+ ions and protons when the Ca2+ ions are released toward the SR lumen.

Exploring the Effectiveness of Carboxymethylated and Crosslinked Albizia procera Gum in Diltiazem Hydrochloride Matrix Tablets: A Comparative Analysis.

This study investigates the efficacy of modified Albizia procera gum as a release-retardant polymer in Diltiazem hydrochloride (DIL) matrix tablets. Carboxymethylated Albizia procera gum (CAP) and ionically crosslinked carboxymethylated Albizia procera gum (Ca-CAP) were utilized, with Ca-CAP synthesized via crosslinking CAP with calcium ions (Ca2+) using calcium chloride (CaCl2). Fourier Transform (FT) IR analysis affirmed polymer compatibility, while differential scanning calorimetry (DSC) and X-ray diffraction (XRD) assessed thermal behavior and crystallinity, respectively. Zeta potential analysis explored surface charge and electrostatic interactions, while rheology examined flow and viscoelastic properties. Swelling and erosion kinetics provided insights into water penetration and stability. CAP's carboxymethyl groups (-CH2-COO-) heightened divalent cation reactivity, and crosslinking with CaCl2 produced Ca-CAP through -CH2-COO- and Ca2+ interactions. Structural similarities between the polymers were revealed by FTIR, with slight differences. DSC indicated modified thermal behavior in Ca-CAP, while Zeta potential analysis showcased negative charges, with Ca-CAP exhibiting lower negativity. XRD highlighted increased crystallinity in Ca-CAP due to calcium crosslinking. Minimal impact on RBC properties was observed with both polymers compared to the positive control as water for injection (WFI). Ca-CAP exhibited improved viscosity, strength, controlled swelling, and erosion, allowing prolonged drug release compared to CAP. Stability studies confirmed consistent six-month drug release, emphasizing Ca-CAP's potential as a stable, sustained drug delivery system over CAP. Robustness and accelerated stability tests supported these findings, underscoring the promise of Ca-CAP in controlled drug release applications.

In vivo heat production dynamics during a contraction-relaxation cycle in rat single skeletal muscle fibers.

Skeletal muscle generates heat via contraction-dependent (shivering) and independent (nonshivering) mechanisms. While this thermogenic capacity of skeletal muscle undoubtedly contributes to the body temperature homeostasis of animals and impacts various cellular functions, the intracellular temperature and its dynamics in skeletal muscle in vivo remain elusive. We aimed to determine the intracellular temperature and its changes within skeletal muscle in vivo during contraction and following relaxation. In addition, we tested the hypothesis that sarcoplasmic reticulum Ca2+ ATPase (SERCA) generates heat and increases the myocyte temperature during a transitory Ca2+-induced contraction-relaxation cycle. The intact spinotrapezius muscle of anesthetized adult male Wistar rats (n = 18) was exteriorized and loaded with the fluorescent probe Cellular Thermoprobe for Fluorescence Ratio (49.3 µM) by microinjection over 1 s. The fluorescence ratio (i.e., 580 nm/515 nm) was measured in vivo during 1) temperature increases induced by means of an external heater, and 2) Ca2+ injection (3.9 nL, 2.0 mM). The fluorescence ratio increased as a linear function of muscle surface temperature from 25 °C to 40 °C (r2 = 0.97, P < 0.01). Ca2+ injection (3.9 nL, 2.0 mM) significantly increased myocyte intracellular temperature: An effect that was suppressed by SERCA inhibition with cyclopiazonic acid (CPA, Ca2+: 38.3 ± 1.4 °C vs Ca2++CPA: 28.3 ± 2.8 °C, P < 0.01 at 1 min following injection). While muscle shortening occurred immediately after the Ca2+ injection, the increased muscle temperature was maintained during the relaxation phase. In this investigation, we demonstrated a novel model for measuring the intracellular temperature of skeletal muscle in vivo and further that heat generation occurs concomitant principally with SERCA functioning and muscle relaxation.

Human Rad51 Protein Requires Higher Concentrations of Calcium Ions for D-Loop Formation than for Oligonucleotide Strand Exchange.

Human Rad51 protein (HsRad51)-promoted DNA strand exchange, a crucial step in homologous recombination, is regulated by proteins and calcium ions. Both the activator protein Swi5/Sfr1 and Ca2+ ions stimulate different reaction steps and induce perpendicular DNA base alignment in the presynaptic complex. To investigate the role of base orientation in the strand exchange reaction, we examined the Ca2+ concentration dependence of strand exchange activities and structural changes in the presynaptic complex. Our results show that optimal D-loop formation (strand exchange with closed circular DNA) required Ca2+ concentrations greater than 5 mM, whereas 1 mM Ca2+ was sufficient for strand exchange between two oligonucleotides. Structural changes indicated by increased fluorescence intensity of poly(dεA) (a poly(dA) analog) reached a plateau at 1 mM Ca2+. Ca2+ > 2 mM was required for saturation of linear dichroism signal intensity at 260 nm, associated with rigid perpendicular DNA base orientation, suggesting a correlation with the stimulation of D-loop formation. Therefore, Ca2+ exerts two different effects. Thermal stability measurements suggest that HsRad51 binds two Ca2+ ions with KD values of 0.2 and 2.5 mM, implying that one step is stimulated by one Ca2+ bond and the other by two Ca2+ bonds. Our results indicate parallels between the Mg2+ activation of RecA and the Ca2+ activation of HsRad51.

Mechanisms of denitrifying granular sludge disintegration and calcium ion-enhanced re-granulation in acidic wastewater treatment.

Granular sludge is an alternative technology for the direct treatment of acidic nitrate-containing wastewater. Rapid remediation of disintegrated granules is essential to achieve efficient nitrogen removal. In this study, denitrifying granules were inactivated and disintegrated when the influent nitrate-nitrogen concentration was elevated from 240 to 360 mg L-1 in acidic wastewater (pH = 4.1) in a sequencing batch reactor. Tightly bound extracellular polymeric substances (TB-EPS) decreased by 60%, and extracellular protein (PN) was the main component of the reduced EPS. The three-dimensional excitation emission matrices (3D-EEM) results confirmed that the PNs that decreased were mainly tryptophan-like, tyrosine-like, and aromatic. This study further confirmed that the decrease in PN was mainly from the destruction of C=O (amide I) and N-H functional groups. Overloading of nitrogen-inhibited denitrifying activity and the destruction and dissolution of TB-EPS by acidic pH were responsible for granule disintegration, with PNs playing a major role in maintaining granule stability. Based on this, new granules with an average particle size of 454.4 µm were formed after calcium chloride addition; EPS nearly doubled during granule formation with PN as the dominant component, accounting for 64.7-78.4% of the EPS. Atomic force microscopy (AFM) revealed that PN-PN adhesion increased by 1.6-4.9 times in the presence of calcium ions, accelerating the re-granulation of disintegrated particles. This study provides new insights into the disintegration and remediation of granular sludge under acidic conditions.

The role of Ca2+ signalling and InsP3R in the pathogenesis of intrahepatic cholestasis of pregnancy.

BACKGROUND: In order to contribute new insights for future prevention and treatment of intrahepatic cholestasis of pregnancy (ICP), and to promote positive pregnancy outcomes, we evaluated serum Ca2+ levels and inositol 1,4,5-trisphosphate receptor (InsP3R) expression in the liver tissue of a rat ICP model. METHODS: After establishing the model by injection of oestradiol benzoate and progesterone into pregnant rats, animals were divided into normal control (n = 5) and ICP model groups (n = 5). The expression of InsP3R protein in the liver, and serum levels of Ca2+, glycocholic acid and bile acid were detected. RESULTS: InsP3R mRNA and protein were significantly lower in the ICP model group compared to the normal group, as determined by qPCR and immunohistochemistry, respectively. Serum enzyme-linked immunosorbent assay results revealed significantly higher levels of glycocholic acid and bile acid in the ICP model group compared to the normal group, while Ca2+ levels were significantly lower. The levers of Ca2+ were significantly and negatively correlated with the levels of glycocholic acid. The observed decrease in Ca2+ was associated with an increase in total bile acids, but there was no significant correlation. CONCLUSIONS: Our results revealed that the expression of InsP3R and serum Ca2+ levels was significantly decreased in the liver tissue of ICP model rats. Additionally, Ca2+ levels were found to be negatively correlated with the level of glycocholic acid.

This study investigated the relationship between serum Ca²⁺ levels, inositol 1,4,5-trisphosphate receptor (InsP3R) expression and intrahepatic cholestasis of pregnancy (ICP) in a rat model. The results indicated a significant decrease in InsP3R expression and Ca²⁺ in the disease group compared to the control group, alongside elevated levels of glycocholic acid and bile acid. The levels of Ca²⁺ exhibited a negative correlation with the levels of glycocholic acid. These findings indicated that the decrease of InsP3R expression and Ca²⁺ levels may be related to the pathogenesis of ICP. The study provides further insight into the treatment of this disease.

Photo-Controlled Calcium Overload from Endogenous Sources for Tumor Therapy.

Designing reactive calcium-based nanogenerators to produce excess calcium ions (Ca2+ ) in tumor cells is an attractive tumor treatment method. However, nanogenerators that introduce exogenous Ca2+ are either overactive incapable of on-demand release, or excessively inert incapable of an overload of calcium rapidly. Herein, inspired by inherently diverse Ca2+ -regulating channels, a photo-controlled Ca2+ nanomodulator that fully utilizes endogenous Ca2+ from dual sources was designed to achieve Ca2+ overload in tumor cells. Specifically, mesoporous silica nanoparticles were used to co-load bifunctional indocyanine green as a photodynamic/photothermal agent and a thermal-sensitive nitric oxide (NO) donor (BNN-6). Thereafter, they were coated with hyaluronic acid, which served as a tumor cell-targeting unit and a gatekeeper. Under near-infrared light irradiation, the Ca2+ nanomodulator can generate reactive oxygen species that stimulate the transient receptor potential ankyrin subtype 1 channel to realize Ca2+ influx from extracellular environments. Simultaneously, the converted heat can induce BNN-6 decomposition to generate NO, which would open the ryanodine receptor channel in the endoplasmic reticulum and allow stored Ca2+ to leak. Both in vitro and in vivo experiments demonstrated that the combination of photo-controlled Ca2+ influx and release could enable Ca2+ overload in the cytoplasm and efficiently inhibit tumor growth.

A chitosan-coated lentinan-loaded calcium alginate hydrogel induces broad-spectrum resistance to plant viruses by activating Nicotiana benthamiana calmodulin-like (CML) protein 3.

Control of plant virus diseases largely depends on the induced plant defence achieved by the external application of synthetic chemical inducers with the ability to modify defence-signalling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a chitosan-coated lentinan-loaded hydrogel and discovered how it protects plants from different virus infections. The hydrogel was synthesized by coating chitosan on the surface of the calcium alginate-lentinan (LNT) hydrogel (SL-gel) to form a CSL-gel. CSL-gels exhibit the capacity to prolong the stable release of lentinan and promote Ca2+ release. Application of CSL-gels on the root of plants induces broad-spectrum resistance against plant viruses (TMV, TRV, PVX and TuMV). RNA-seq analysis identified that Nicotiana benthamiana calmodulin-like protein gene 3 (NbCML3) is upregulated by the sustained release of Ca2+ from the CSL-gel, and silencing and overexpression of NbCML alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that this novel and synthetic CSL-gel strongly inhibits the infection of plant viruses by the sustainable release of LNT and Ca2+ . This study uncovers a novel mode of action by which CSL-gels trigger NbCML3 expression through the stable and sustained release of Ca2+ .

Unraveling the connection between calreticulin and myeloproliferative neoplasms via calcium signaling.

Mutations in the form of insertions and deletions (INDEL) in the calreticulin gene lead to essential thrombocythemia (ET) which is characterized by the formation of thrombosis. However, the connection between calreticulin INDEL and ET remains largely elusive. Through combined molecular dynamics simulation, clustered regularly interspaced short palindromic repeats (CRISPR) and calcium imaging studies on the wild type and mutated isoforms of calreticulin, the mechanism underlying the calreticulin INDEL induced ET was investigated at the molecular level. Our results demonstrate that mutations in exon-9 could lead to significant conformational variations of calreticulin structure and thereby reducing its interaction with calcium ions due to decreased electrostatic contributions. The consequence of mutations on calreticulin's structural integrity was revealed by identifying the key residues and their roles in calcium binding. Furthermore, mutations implemented by CRISPR-Cas9 in exon-9 showed diminished calcium signaling in HEK-293T cells, which agree well with our in-silico findings. The current study might help in understanding the variations of molecular interactions between calreticulin's exon-9 and calcium ions during physiological and pathological conditions. The results might also provide useful information for designing novel therapeutic approaches targeting ET.