Search Results (49)

Bacteriocins from lactic acid bacteria have attracted considerable attention as natural alternatives to conventional antimicrobial agents. Weissellicin LM85, a bacteriocin purified from Weissella confusa LM85, has been less extensively studied in terms of its mechanism of action and potential applications. In this study, purified weissellicin LM85 exhibited potent inhibitory effects against Gram-positive bacteria, with minimum inhibitory and bactericidal concentrations determined against Micrococcus luteus MTCC106. Time-kill assays and fluorescence staining indicated a concentration-dependent reduction in cell viability, accompanied by membrane disruption. Further analyses revealed potassium ion efflux, dissipation of membrane potential (Δψ) and pH gradient (ΔpH), genomic DNA fragmentation, and pronounced morphological alterations in target cells. These findings are strongly suggestive of membrane-targeted bactericidal activity, likely involving pore-forming effects. In addition, weissellicin LM85 inhibited both growth and biofilm formation of Salmonella enterica subsp. enterica serovar Typhimurium ATCC13311 and Staphylococcus aureus subsp. aureus ATCC25923. Mechanistic analyses revealed the disruption of cell membrane integrity, leakage of potassium ions, cytoplasmic contents, and non-specific DNA degradation, indicating a multifaceted antibacterial mode of action. These findings highlight weissellicin LM85 as a promising natural antimicrobial with potential applications in food preservation and the control of foodborne pathogens and biofilm-associated infections. Further studies on cytotoxicity and in vivo efficacy are required to advance its practical application. Full article

Curcumin, a polyphenolic compound derived from Curcuma longa, has drawn significant attention for its pleiotropic pharmacological activities, including anti-inflammatory and anticancer effects. Pyroptosis, an inflammatory form of programmed cell death mediated by inflammasome activation and gasdermin cleavage, has emerged as a critical target in both chronic inflammatory diseases and cancer therapy. This review comprehensively explores the dual roles of curcumin in the regulation of NLRP3 inflammasome-mediated pyroptosis. Curcumin exerts inhibitory effects by suppressing NF-κB signaling, attenuating mitochondrial reactive oxygen species (ROS) and ER stress, preventing potassium efflux, and disrupting inflammasome complex assembly. Conversely, in certain cancer contexts, curcumin promotes pyroptosis by stabilizing NLRP3 through the inhibition of Smurf2-mediated ubiquitination. Molecular docking studies support curcumin’s direct binding to several pyroptosis-associated proteins, including NLRP3, AMPK, caspase-1, and Smurf2. These context-dependent regulatory effects underscore the therapeutic potential of curcumin as both an inflammasome suppressor in inflammatory diseases and a pyroptosis inducer in cancer. Full article

Investigations of CO₂ emissions in the context of different tillage systems are relevant not only for studying the effects of climate change but also for evaluating the sustainability of soil management. To better understand the influence of soil physico-chemical properties on CO₂ emissions, an experiment was conducted to measure the direct and indirect effects of these soil properties on CO₂ efflux. Soil CO₂ efflux is measured using a closed chamber method (LI-COR LI-8100A) under various tillage in two soil textures. Our research revealed that soil temperature, water content, soil organic carbon, total nitrogen, available phosphorus and pH significantly affected the soil–atmosphere CO₂ exchange rate. Soil CO₂, volumetric water content and soil temperature were higher in loam soil than in sandy loam soil. Soil CO₂ efflux was 8.6% lower in conventional tillage than under reduced and no tillage. Total nitrogen and soil organic carbon contents are dependent on tillage and decreased from no tillage to conventional tillage. Soil agrochemical properties such as SOC, total nitrogen, available phosphorus, available potassium and soil pH were higher evaluated in loam soil than in sandy loam soil. The results of this research are valuable contributions to knowledge on soil management in relation to CO₂ emissions on morainic loamy soil. Full article

Magnesium (Mg) deficiency is increasingly recognized as a critical factor limiting crop production, especially in soils with high potassium (K) application. This study investigated the effects of different Mg fertilizers (MgSO₄ and Mg(OH)₂-based nanofertilizer) on K–Mg interactions in hydroponically grown tomato seedlings, with varying K (0.7, 7, and 21 mM) and Mg (0.1 and 1 mM) supply concentrations. The results observed with MgSO₄ application showed that high K levels (21 mM) significantly antagonized Mg uptake, reducing total Mg content and negatively affecting plant growth and root-to-shoot ratios at both Mg supply levels. Specifically, the K3 (21 mM) treatment reduced total biomass by 45.35% compared to the K2 (7 mM) treatment. Moreover, a high K supply combined with low Mg intake exacerbated Mg deficiency. The optimal K:Mg ratio for growth was found to be 7:1. K–Mg antagonism occurred primarily during root uptake, with excessive K leading to increased Mg²⁺ efflux in the root elongation zone. Notably, the application of Mg(OH)₂ nanoparticles alleviated K-induced Mg deficiency, as indicated by the lack of a significant correlation between K supply and relative Mg concentrations in plants treated with nano-Mg across K:Mg ratios ranging from 7:0.1 to 21:0.1. However, Mg concentration decreased by 17.54% and 35.63% in shoots and by 27.72% and 37.08% in roots for K2 and K3, respectively, in plants treated with MgSO₄. It is concluded that optimizing K:Mg ratios and using Mg-based nanofertilizers can improve K and Mg utilization in high-K soils. Full article

Cronobacter sakazakii, an opportunistic foodborne pathogen, has a strong resistance to osmotic stress and desiccation stress, but the current studies cannot elucidate this resistance mechanism absolutely. A mechanosensitive channel MscM was suspected of involving to desiccation resistance mechanism of C. sakazakii. To investigate the specific molecular mechanism, the mscM mutant strain (ΔmscM) was constructed using the homologous recombination method, and the cpmscM complementary strain was obtained by gene complementation, followed by the analysis of the difference between the wild-type (WT), mutant, and complementary strains. Compared to the wild-type bacteria (WT), the inactivation rate of the ΔmscM strain decreased by 15.83% (p < 0.01) after desiccation stress. The absence of the mscM gene led to an increase in the membrane permeability of mutant strains. Through turbidity assay, it was found that the intracellular content of potassium ion (K⁺) of the ΔmscM strain increased by 2.2-fold (p < 0.05) compared to the WT strain, while other metal ion contents, including sodium ion (Na⁺), calcium ion (Ca²⁺), and magnesium ion (Mg²⁺), decreased by 48.45% (p < 0.001), 24.29% (p < 0.001), and 26.11% (p < 0.0001), respectively. These findings indicate that the MscM channel primarily regulates cell membrane permeability by controlling K⁺ efflux to maintain the homeostasis of intracellular osmotic pressure and affect the desiccation tolerance of bacteria. Additionally, the deletion of the mscM gene did not affect bacterial growth and motility but impaired surface hydrophobicity (reduced 20.52% compared to the WT strain, p < 0.001), adhesion/invasion capability (reduced 26.03% compared to the WT strain, p < 0.001), and biofilm formation ability (reduced 30.19% compared to the WT strain, p < 0.05) of the bacteria. This study provides a reference for the role of the mscM gene in the desiccation resistance and biofilm formation of C. sakazakii. Full article

Maintaining extracellular potassium (K⁺) within narrow limits, critical for membrane potential and excitability, is accomplished through the internal redistribution of K⁺ between extracellular fluid (ECF) and intracellular fluid (ICF) in concert with the regulation of renal K⁺ output to balance K⁺ intake. Here we present evidence from high-precision analyses of stable K⁺ isotopes in rats maintained on a control diet that the tissues and organs involved in the internal redistribution of K⁺ differ in their speed of K⁺ exchange with ECF and can be grouped into those that exchange K⁺ with ECF either rapidly or more slowly (“fast” and “slow” pools). After 10 days of K⁺ restriction, a compartmental analysis indicates that the sizes of the ICF K⁺ pools decreased but that this decrease in ICF K⁺ pools was not homogeneous, rather occurring only in the slow pool (15% decrease, p < 0.01), representing skeletal muscles, not in the fast pool. Furthermore, we find that the dietary K⁺ restriction is associated with a decline in the rate constants for K⁺ effluxes from both the “fast” and “slow” ICF pools (p < 0.05 for both). These results suggest that changes in unidentified transport pathways responsible for K⁺ efflux from ICF to ECF play an important role in buffering the internal redistribution of K⁺ between ICF and ECF during K⁺ restriction. Thus, the present study introduces novel stable isotope approaches to separately characterize heterogenous ICF K⁺ pools in vivo and assess K⁺ uptake by individual tissues, methods that provide key new tools to elucidate K⁺ homeostatic mechanisms in vivo. Full article

Hypokalemic paralysis is a clinical syndrome characterized by acute flaccid paralysis with concomitant hypokalemia. Complications, such as acute respiratory failure and cardiac arrhythmias, can be fatal. If treated appropriately, the patient can recover without any sequelae. We present a rare case of life-threatening hypokalemic paralysis following the ingestion of an unknown substance. At presentation, her serum potassium concentration was 1.9 mmol/L. A review of the patient’s history confirmed the ingestion of barium chloride. She was diagnosed with acute barium poisoning characterized by high serum and urine barium levels. Aggressive potassium repletion was administered intravenously and orally. Her serum potassium concentration dropped to 1.5 mmol/L and peaked at 5.4 mmol/L following treatment. The patient achieved a complete recovery and was discharged without sequelae. Barium can competitively block the potassium inward rectifier channels and interfere with the efflux of intracellular potassium, leading to severe hypokalemia. Our report illustrates a rare presentation of acute barium intoxication and a differential diagnosis indicating hypokalemic paralysis. We also discuss the pathophysiological features and compare the clinical findings with cases of rebound hyperkalemia. Full article

Human defensins are cysteine-rich peptides (Cys-rich peptides) of the innate immune system. Defensins contain an ancestral structural motif (i.e., γ-core motif) associated with the antimicrobial activity of natural Cys-rich peptides. In this study, low concentrations of human α- and β-defensins showed microbicidal activity that was not associated with cell membrane permeabilization. The cell death pathway was similar to that previously described for human lactoferrin, also an immunoprotein containing a γ-core motif. The common features were (1) cell death not related to plasma membrane (PM) disruption, (2) the inhibition of microbicidal activity via extracellular potassium, (3) the influence of cellular respiration on microbicidal activity, and (4) the influence of intracellular pH on bactericidal activity. In addition, in yeast, we also observed (1) partial K⁺-efflux mediated via Tok1p K⁺-channels, (2) the essential role of mitochondrial ATP synthase in cell death, (3) the increment of intracellular ATP, (4) plasma membrane depolarization, and (5) the inhibition of external acidification mediated via PM Pma1p H⁺-ATPase. Similar features were also observed with BM2, an antifungal peptide that inhibits Pma1p H⁺-ATPase, showing that the above coincident characteristics were a consequence of PM H⁺-ATPase inhibition. These findings suggest, for the first time, that human defensins inhibit PM H⁺-ATPases at physiological concentrations, and that the subsequent cytosolic acidification is responsible for the in vitro microbicidal activity. This mechanism of action is shared with human lactoferrin and probably other antimicrobial peptides containing γ-core motifs. Full article

Hearing loss can result from impairments in structures that support endocochlear potential, as they play a crucial role in the transduction and transmission of auditory waves. This aspect has been the subject of several studies to date. In our review, the role of ion transport channels and pumps involved in hearing function has been highlighted, emphasizing how important the Kir4.1 channel is in maintaining the endocochlear potential. The Kir4.1 channel, a member of the inwardly rectifying potassium channel (Kir) family, plays a key role in the regulation of cell electrical activity and potassium ion homeostasis. The cochlear expression of these channels is at the level of the intermediate cells of the vascular stria, in the root cells of the outer sulcus, and in the glial cells of the spiral ganglion. In development, its expression demonstrates its involvement in the progression of pathologies related to potassium channel dysfunction, and its activation in the stria vascularis is directly related to the generation of endocochlear potential. Kir4.1 is fundamental in stabilizing the resting membrane potential of cells and modulating their excitability, as it facilitates a greater influx of potassium into cells compared to efflux when the membrane potential is negative. Mutations in the K⁺ channel gene KCNJ10 (Kir4.1) have been associated with several disorders, with the most significant studies on EAST/SeSAME syndrome and Pendred syndrome. Recent research has explored the metabolic importance of potassium channel changes associated with stria vascularis degeneration in the progression of age-related hearing loss. Furthermore, in ototoxicity studies, the Kir4.1 channel has been shown to have the ability to compensate for the deficiency of other K⁺ channels, as it maintains the cochlear homeostasis by correcting the imbalanced K⁺ concentration. Full article

High-voltage electrical injuries, especially from lightning strikes, can cause life-threatening complications due to extreme temperature and voltage exposure. While burns and cardiac complications have been widely described, the documentation of metabolic imbalances, particularly hypokalemia, has not been as prevalent. This report focuses on a patient with profound transient hypokalemia following a lightning strike, alongside a review of three similar cases of transient hypokalemia from the literature. Our patient, a previously healthy young man, was struck by lightning and subsequently suffered transient hypokalemia with lower extremity sensory changes, which resolved after the normalization of serum potassium levels. While the exact underlying mechanisms of transient hypokalemia following high-voltage electrical injuries are unknown, we propose a multifactorial mechanism, which includes massive intracellular shifts of potassium due to elevated epinephrine levels and the prevention of potassium efflux through the electrical disruption of voltage-gated potassium channels. Our report underscores the importance of recognizing hypokalemia in patients with high-voltage electrical injuries and contributes to the understanding of the complex mechanisms involved. Further research is necessary to understand the connection between cellular changes induced by high-voltage exposure and their effects on metabolism, particularly in relation to hypokalemia. Full article

Background: Observational studies of intermittent hemodialysis therapy have reported that the excess decrease in K⁺ concentration in plasma (KP) during treatment is associated with the destabilization of cardiac function. Elucidating the mechanism by which the decrease in KP impairs myocardial excitation is indispensable for a deeper understanding of prescription design. Methods: In this study, by using an electrophysiological mathematical model, we investigated the relationship between KP dynamics and cardiomyocyte excitability for the first time. Results: The excess decrease in KP during treatment destabilized cardiomyocyte excitability through the following events: (1) a decrease in KP led to the prolongation of the depolarization phase of ventricular cells due to the reduced potassium efflux rate of the Kr channel, temporarily enhancing contraction force; (2) an excess decrease in KP activated the transport of K⁺ and Na⁺ through the funny channel in sinoatrial nodal cells, disrupting automaticity; (3) the excess decrease in KP also resulted in a significant decrease in the resting membrane potential of ventricular cells, causing contractile dysfunction. Avoiding an excess decrease in KP during treatment contributed to the maintenance of cardiomyocyte excitability. Conclusions: The results of these mathematical analyses showed that it is necessary to implement personal prescription or optimal control of K⁺ concentration in dialysis fluid based on predialysis KP from the perspective of regulatory science in dialysis treatment. Full article

Actinobacillus pleuropneumoniae (APP) is responsible for causing Porcine pleuropneumonia (PCP) in pigs. However, using vaccines and antibiotics to prevent and control this disease has become more difficult due to increased bacterial resistance and weak cross-immunity between different APP types. Naringin (NAR), a dihydroflavonoid found in citrus fruit peels, has been recognized as having significant therapeutic effects on inflammatory diseases of the respiratory system. In this study, we investigated the effects of NAR on the inflammatory response caused by APP through both in vivo and in vitro models. The results showed that NAR reduced the number of neutrophils (NEs) in the bronchoalveolar lavage fluid (BALF), and decreased lung injury and the expression of proteins related to the NLRP3 inflammasome after exposure to APP. In addition, NAR inhibited the nuclear translocation of nuclear factor kappa-B (NF-κB) P65 in porcine alveolar macrophage (PAMs), reduced protein expression of NLRP3 and Caspase-1, and reduced the secretion of pro-inflammatory cytokines induced by APP. Furthermore, NAR prevented the assembly of the NLRP3 inflammasome complex by reducing protein interaction between NLRP3, Caspase-1, and ASC. NAR also inhibited the potassium (K⁺) efflux induced by APP. Overall, these findings suggest that NAR can effectively reduce the lung inflammation caused by APP by inhibiting the over-activated NF-κB/NLRP3 signalling pathway, providing a basis for further exploration of NAR as a potential natural product for preventing and treating APP. Full article

High concentrations of sodium (Na⁺), chloride (Cl⁻), calcium (Ca²⁺), and sulphate (SO₄²⁻) are frequently found in saline soils. Crop plants cannot successfully develop and produce because salt stress impairs the uptake of Ca²⁺, potassium (K⁺), and water into plant cells. Different intracellular and extracellular ionic concentrations change with salinity, including those of Ca²⁺, K⁺, and protons. These cations serve as stress signaling molecules in addition to being essential for ionic homeostasis and nutrition. Maintaining an appropriate K⁺:Na⁺ ratio is one crucial plant mechanism for salt tolerance, which is a complicated trait. Another important mechanism is the ability for fast extrusion of Na⁺ from the cytosol. Ca²⁺ is established as a ubiquitous secondary messenger, which transmits various stress signals into metabolic alterations that cause adaptive responses. When plants are under stress, the cytosolic-free Ca²⁺ concentration can rise to 10 times or more from its resting level of 50–100 nanomolar. Reactive oxygen species (ROS) are linked to the Ca²⁺ alterations and are produced by stress. Depending on the type, frequency, and intensity of the stress, the cytosolic Ca²⁺ signals oscillate, are transient, or persist for a longer period and exhibit specific “signatures”. Both the influx and efflux of Ca²⁺ affect the length and amplitude of the signal. According to several reports, under stress Ca²⁺ alterations can occur not only in the cytoplasm of the cell but also in the cell walls, nucleus, and other cell organelles and the Ca²⁺ waves propagate through the whole plant. Here, we will focus on how wheat and other important crops absorb Na⁺, K⁺, and Cl⁻ when plants are under salt stress, as well as how Ca²⁺, K⁺, and pH cause intracellular signaling and homeostasis. Similar mechanisms in the model plant Arabidopsis will also be considered. Knowledge of these processes is important for understanding how plants react to salinity stress and for the development of tolerant crops. Full article

Sulfite is a common preservative in wine, but the spoilage yeast Brettanomyces bruxellensis can produce volatile phenols even with the recommended sulfite dose. The purpose of this study was to examine how wine components, p-coumaric acid (a precursor of volatile phenols), and micronutrients influence culturability, viability, and volatile phenols production by B. bruxellensis under sulfite stress. In red wine, a high sulfite dose (potassium metabisulfite, 100 mg L⁻¹) led to an immediate death phase followed by growth recovery after two weeks. However, 4-ethylphenol (4-EP) was continuously produced by dead or nonculturable cells. Nonetheless, an event of growth recovery could not be observed in the case of the model wine. However, when the model wine was supplemented with minerals and vitamins, both growth recovery and 4-EP production were noticed, suggesting that the minerals and vitamins played an important role in maintaining the viability of cells under the sulfite stress. The yeast could also utilize the p-coumaric acid (p-CA) as an energy source, showing a specific growth rate of 0.0142 h⁻¹ with 1 mM of p-CA in model wine. Furthermore, the sulfite-stressed cells exhibited ATP production by means of proton efflux while utilizing the p-CA. This work highlights the novel finding that the conversion of p-CA into 4-EP provides sufficient energy for the cell to remain metabolically active under the sulfite stress. Full article

Cucurbita species are widely used as rootstocks for cucumber, watermelon, and other plants for the restriction of toxic Na⁺ transport from root to shoot. Previous studies have found distinct salt tolerance strategies between Cucurbita moschata and Cucurbita maxima; the former accumulates a large amount of Na⁺ in the root, while the latter accumulates Na⁺ in the shoot. To further study the mechanism of Na⁺ transport in plants, four reciprocal grafts were made between MB (C. moschata) and JHL (C. maxima), denoted as MB/MB, JHL/JHL, MB/JHL, and JHL/MB (scion/rootstock). The results showed that using MB as the rootstock effectively reduced the accumulation of Na⁺ in the scion. Conversely, JHL rootstock tended to transfer more Na⁺ to the scion. To clarify this phenomenon, the velocities of Na⁺ flows on the root surface, stem, and vein of grafting combinations were measured using non-invasive micro-test technology. Compared with the seedlings using JHL as rootstock, the grafted combination with MB as rootstock had a higher root Na⁺ efflux and lower Na⁺ fluxes in the stem and vein. qRT-PCR analyses revealed the critical roles of salt overly sensitive 1 and high-affinity potassium as components of the mechanism enabling Na⁺ exclusion from the root and Na⁺ unloading from the stem xylem. Compared with the seedlings using MB as rootstocks, the JHL-grafted plants showed more rapid stomatal closure and decreased transpiration rate in the first three hours after salt stress but maintained a higher level under prolonged salt treatment (120 h). The tissue tolerances of JHL and MB were assessed using the isolated leaves under NaCl to exclude the influence of the root and stem. The results showed that the salinity inflicted more serious damage to MB leaves than to JHL leaves. qRT-PCR analyses indicated that the intracellular Na⁺/H⁺ transporter in the leaf vein was involved in this process. All these findings indicated that C. moschata and C. maxima adopted different strategies for regulating Na⁺ transport, and grafting can be used as a tool to create more salt-tolerant plants. Full article