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The maintenance of sodium/potassium (Na+ /K+ ) homeostasis in plant cells is essential for salt tolerance. Plants export excess Na+ out of cells mainly through the Salt Overly Sensitive (SOS) pathway, activated by a calcium signal; however, it is unknown whether other signals regulate the SOS pathway and how K+ uptake is regulated under salt stress. Phosphatidic acid (PA) is emerging as a lipid signaling molecule that modulates cellular processes in development and the response to stimuli. Here, we show that PA binds to the residue Lys57 in SOS2, a core member of the SOS pathway, under salt stress, promoting the activity and plasma membrane localization of SOS2, which activates the Na+ /H+ antiporter SOS1 to promote the Na+ efflux. In addition, we reveal that PA promotes the phosphorylation of SOS3-like calcium-binding protein 8 (SCaBP8) by SOS2 under salt stress, which attenuates the SCaBP8-mediated inhibition of Arabidopsis K+ transporter 1 (AKT1), an inward-rectifying K+ channel. These findings suggest that PA regulates the SOS pathway and AKT1 activity under salt stress, promoting Na+ efflux and K+ influx to maintain Na+ /K+ homeostasis.
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Proteínas de Arabidopsis , Arabidopsis , Proteínas Serina-Treonina Quinases , Estresse Salino , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Homeostase , Ácidos Fosfatídicos/metabolismo , Potássio/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Estresse Salino/genética , Sódio/metabolismoRESUMO
The regulation of intracellular pH in yeast (Saccharomyces cerevisiae) cells is critical for cell function and viability. In yeast, protons (H+) can be excreted from the cell by plasma membrane ATPase PMA1 and pumped into vacuoles by vacuolar H+-ATPase. Because PMA1 is critical to the survival of yeast cells, it is unknown whether other compensatory components are involved in pH homeostasis in the absence of PMA1. To elucidate how intracellular pH is regulated independently of PMA1, we employed a screening approach by exposing the yeast haploid deletion mutant library (ver 4.0) to the selective plant plasma membrane H+-ATPase inhibitor PS-1, which we previously reported. After repeated screenings and verification, we identified two proteins, Aly1 and Aly2, that play a role in the regulation of intracellular pH when PMA1 is deficient. Our research uncovers a new perspective on the regulation of intracellular pH related to PMA1 and also preliminarily reveals a role for Aly1 and Aly2 in the regulation of intracellular pH.
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Furfural residue (FR), a solid waste, was applied as the precursor to prepare activated carbon by steam activation. The Box-Behnken design (BBD) approach-based response surface methodology (RSM) was utilized to optimize the preparation conditions to evaluate their effects on the performance of activated carbon from furfural residue (FRAC). The optimum preparation conditions of FRAC were found as follows: activation temperature of 922 °C, activation time of 62 min, and the mass ratio of char to H2O of 1:4.5, resulting in 1,501.84 mg/g of iodine adsorption capacity and 1,662.41 m2/g of specific surface area. The FRAC was characterized and then the adsorption performance of bisphenol S (BPS) on FRAC was investigated. Langmuir and Koble-Corrigan isotherm models were well fitted to the experimental data, and the adsorption kinetics process was perfectly described by the pseudo-second-order model. Thermodynamic parameters showed that the adsorption of BPS was a spontaneous exothermic process. Besides, the regeneration efficiency of FRAC was over 97% after five consecutive cycles. The maximum monolayer adsorption capacity of FRAC for BPS was 3.2848 mmol/g at 298 K, indicating that the FRAC was an excellent adsorbent for the removal of BPS from aqueous solutions.
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Carvão Vegetal , Poluentes Químicos da Água , Adsorção , Furaldeído , Concentração de Íons de Hidrogênio , Cinética , Fenóis , Sulfonas , Termodinâmica , Poluentes Químicos da Água/análiseRESUMO
A novel N-doped activated carbon (NAC) derived from shaddock peel was investigated to remove norfloxacin (NFX) from aqueous solution. The Box-Behnken central composite design (BBD) was used to optimize the preparation conditions of NAC. The specific surface area of NAC was 2,481.81 m2 g-1, which was obtained at 1,106 K activation temperature, 2.4 h residence time, and 2.3:1 mass ratio of KOH to hydrochar. Moreover, the equilibrium data were perfectly represented by Langmuir and Koble-Corrigan isotherms, and the adsorption process was precisely described by the pseudo-second-order kinetic model. Besides, the adsorption of NFX on NAC was mainly controlled by π-π electron-donor-acceptor (EDA) interaction, hydrophobic effect, hydrogen-bonding, electrostatic interaction and Lewis acid-base effect. The maximum monolayer adsorption capacity of NFX was 746.29 mg g-1 at 298 K, implying that NAC was a promising adsorbent for the removal of NFX from aqueous solution.
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Norfloxacino , Poluentes Químicos da Água , Adsorção , Carvão Vegetal/química , Água , Poluentes Químicos da Água/químicaRESUMO
Mass production of nanomaterials to remove pollutants from water still faces many challenges, mainly due to the complexity of the synthesis methods involved and the use of dangerous reagents. The green method of preparation of nanomaterials from plants can effectively solve these problems. Fe,Cu oxide nanocomposites (Fe-Cu-NCs) were synthesized by a green and single-step method using loquat leaf extracts, and were used as an adsorbent for removal of Norfloxacin (NOR) and Ciprofloxacin (CIP) from aqueous solution. The synthesized adsorbent showed excellent adsorption properties for NOR and CIP. The experimental equilibrium data fitted the Redlich-Peterson and Koble-Corrigan models well and the maximum adsorption capacities of Fe-Cu-NCs calculated by the Langmuir model for NOR and CIP were 1.182 mmol/g and 1.103 mmol/g, respectively, at 293 K. Additionally, the morphologies and properties of Fe-Cu-NCs were characterized by transmission electron microscopy (TEM), scanning electron microscopy X-ray energy-dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis and the adsorption mechanism of NOR and CIP onto Fe-Cu-NCs was discussed. Thermodynamic parameters revealed that the adsorption process was spontaneous and endothermic. This study indicated that Fe-Cu-NCs are a potential adsorbent and provide a simple and convenient strategy for the purification of antibiotics-laden wastewater.
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Eriobotrya , Nanocompostos , Poluentes Químicos da Água , Adsorção , Ciprofloxacina , Cinética , Norfloxacino , Óxidos , Extratos Vegetais , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
FLOWERING LOCUS T2 (FT2) is the closest paralog of the FT1 flowering gene in the temperate grasses. Here we show that overexpression of FT2 in Brachypodium distachyon and barley results in precocious flowering and reduced spikelet number, while down-regulation by RNA interference results in delayed flowering and a reduced percentage of filled florets. Similarly, truncation mutations of FT2 homeologs in tetraploid wheat delayed flowering (2-4 d) and reduced fertility. The wheat ft2 mutants also showed a significant increase in the number of spikelets per spike, with a longer spike development period potentially contributing to the delayed heading time. In the wheat leaves, FT2 was expressed later than FT1, suggesting a relatively smaller role for FT2 in the initiation of the reproductive phase. FT2 transcripts were detected in the shoot apical meristem and increased during early spike development. Transversal sections of the developing spike showed the highest FT2 transcript levels in the distal part, where new spikelets are formed. Our results suggest that, in wheat, FT2 plays an important role in spike development and fertility and a limited role in the timing of the transition between the vegetative and reproductive shoot apical meristem.
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Brachypodium/genética , Flores/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Hordeum/genética , Proteínas de Plantas/genética , Triticum/genética , Brachypodium/crescimento & desenvolvimento , Fertilidade/genética , Flores/genética , Genes de Plantas/genética , Hordeum/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Reprodução/genética , Triticum/crescimento & desenvolvimentoRESUMO
Plasma membrane (PM) H+-ATPase is essential for plant growth and development. Various environmental stimuli regulate its activity, a process that involves many protein cofactors. However, whether endogenous small molecules play a role in this regulation remains unknown. Here, we describe a bio-guided isolation method to identify endogenous small molecules that regulate PM H+-ATPase activity. We obtained crude extracts from Arabidopsis seedlings with or without salt treatment and then purified them into fractions based on polarity and molecular mass by repeated column chromatography. By evaluating the effect of each fraction on PM H+-ATPase activity, we found that fractions containing the endogenous, free unsaturated fatty acids oleic acid (C18:1), linoleic acid (C18:2), and linolenic acid (C18:3) extracted from salt-treated seedlings stimulate PM H+-ATPase activity. These results were further confirmed by the addition of exogenous C18:1, C18:2, or C18:3 in the activity assay. The ssi2 mutant, with reduced levels of C18:1, C18:2, and C18:3, displayed reduced PM H+-ATPase activity. Furthermore, C18:1, C18:2, and C18:3 directly bound to the C-terminus of the PM H+-ATPase AHA2. Collectively, our results demonstrate that the binding of free unsaturated fatty acids to the C-terminus of PM H+-ATPase is required for its activation under salt stress. The bio-guided isolation model described in this study could enable the identification of new endogenous small molecules that modulate essential protein functions, as well as signal transduction, in plants.
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Arabidopsis/enzimologia , ATPases Translocadoras de Prótons/metabolismo , Bioensaio , Fracionamento Celular , Membrana Celular/metabolismo , Condutividade Elétrica , Ativação Enzimática , Ácido Linoleico/metabolismo , Ácido Oleico/metabolismo , Ácido alfa-Linolênico/metabolismoRESUMO
This study aimed at a systematic review and meta-analysis of all available randomized controlled trials (RCTs) using acupuncture to treat tinnitus. Five electronic databases, in both English and Chinese, were searched. All studies in our review and meta-analysis included parallel RCTs of tinnitus patients which compared subjects receiving acupuncture (or its other forms, such as electroacupuncture) to subjects receiving no treatment, sham treatment, drugs or basic medical therapy. Data from the articles were validated and extracted using a predefined data extraction form. Nearly all of Chinese studies reported positive results, while most of English studies reported negative results. Analysis of the combined data found that the acupuncture treatments seemed to provide some advantages over conventional therapies for tinnitus. It had difference in acupuncture points and sessions between Chinese studies and English studies. Methodological flaws were also found in many of the RCTs, especially in Chinese studies. The results of this review suggest that acupuncture therapy may offer subjective benefit to some tinnitus patients. Acupuncture points and sessions used in Chinese studies may be more appropriate, whereas these studies have many methodological flaws and risk bias, which prevents us making a definitive conclusion.
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Terapia por Acupuntura/métodos , Zumbido/terapia , HumanosRESUMO
OBJECTIVE: To compare the effects of thoracotomy and total thoracoscopic surgery on coronary artery fistulae complicated with ectasia. METHODS: Forty-six patients with coronary artery fistulae complicated with ectasia were randomly divided into a treatment group and a control group (n=23) which were given totally thoracoscopic surgery and thoracotomy respectively. Both groups were followed up. RESULTS: All patients survived the surgeries and were discharged from the hospital. The treatment group had significantly less intraoperative blood loss, earlier postoperative ambulation and shorter postoperative hospitalization stay more than those of the control group (P<0.05). The two groups had similar plasm cortisol and adrenocorticotropic hormone levels one day before and after surgery. These levels peaked on the postoperative 3rd day, but those of the treatment group were significantly lower (P<0.05). The two groups had similar left and right atrial diameters as well as left ventricular ejection fractions (LVEFs) before surgery, but the treatment group had significantly higher postoperative LVEF (P<0.05) as well as significantly smaller left and right atrial diameters in the postoperative 1st and 3rd months (P<0.05). The treatment group was significantly less prone to postoperative complications such as chest pain, atelectasis and pulmonary infection than the control group (P<0.05). CONCLUSION: Total thoracoscopic surgery promoted the recovery of coronary artery fistulae complicated with ectasia, improved cardiac remodeling and cardiac function, and alleviated stress reaction, with well-proved safety.
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Multiple cell death pathways are involved in neuronal death in ischemic stroke (IS). However, the role of different cell death pathways in different cell types has not been elucidated. By analyzing three single-nucleus RNA sequencing (snRNA-seq) data of IS, we first found that a variety of programmed cell death (PCD) -related genes were significantly changed in different cell types. Based on machine learning and virtual gene knockout, we found that ferroptosis related genes, ferritin heavy chain 1 (Fth1) and ferritin light chain (Ftl1), play a key role in IS. Ftl1 and Fth1 can promote microglia activation, as well as the production of inflammatory factors and chemokines. Cell communication analysis showed that activated microglia could enhance chemotactic peripheral leukocyte infiltration, such as macrophages and neutrophils, through Spp1-Cd44 and App-Cd74 signaling, thereby aggravating brain tissue damage. Furthermore, real-time quantitative polymerase chain reaction (RT-qPCR) showed that P2ry12 and Mef2c were significantly decreased in oxygen-glucose deprivation (OGD) group, while Ftl1, Fth1, Apoe, Ctsb, Cd44 and Cd74 were significantly increased in OGD group. Collectively, our findings suggested targeted therapy against microglia Ftl1 and Fth1 might improve the state of microglia, reduce the infiltration of peripheral immune cells and tissue inflammation, and then improve the ischemic brain injury in mouse.
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BACKGROUND: Though generally a mild affliction, allergic rhinitis (AR) is very common and causes considerable discomfort. Ephedra sinica polysaccharide is a candidate cost-effective therapy to relieve AR symptoms. PURPOSE: We explore the molecular mechanism of pure polysaccharide ESP-B4 action in AR. METHODS: RPMI2650 cells were treated with lipopolysaccharide to induce an in vitro sensitization model, and extracellular vesicles (EVs) were isolated. A rat model of AR was established using ovalbumin as the allergen and was treated with Ephedra sinica polysaccharide to observe changes in rhinitis symptoms, nasal mucosa histopathology and molecular pathology. ESP-B4-treated sensitized cells were adopted in vitro to verify effect of Ephedra sinica polysaccharide on miR-146a-5p expression in RPMI2650 cell-derived EVs and helper T cell differentiation. RESULTS: miR-146a-5p inhibited Smad3, impeded the Smad3/GATA-3 interaction, upregulated IFN-γ expression, and promoted CD4+T cell Th1 differentiation. Treatment with ESP-B4 relieved AR in rats, and elevated miR-146a-5p in the EVs from the nasal epithelial cells, apparently in relation to effects on helper T cell Th1/Th2 equilibrium. CONCLUSION: Overall, ESP-B4 can promote miR-146a-5p secretion, affect the Th1/Th2 balance of helper T cells, and relieve AR symptoms through Smad3/GATA-3 interaction, thus presenting a potential strategy for AR treatment.
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Ephedra sinica , Vesículas Extracelulares , MicroRNAs , Rinite Alérgica , Ratos , Animais , Rinite Alérgica/tratamento farmacológico , Células Epiteliais/metabolismo , Vesículas Extracelulares/metabolismo , Lipopolissacarídeos , MicroRNAs/genética , MicroRNAs/metabolismoRESUMO
OBJECTIVE: To study the adjunctive roles of Qingliu Lianghou Recipe (QLR) in treatment of hypopharyngeal carcinoma. METHODS: A total of 156 patients with hypopharyngeal squamous cell carcinoma were recruited, including 21 cases of stage I, 34 in stage II, 55 in stage III, and 46 in stage IV. Of them, 31 patients (Group A) were managed with operation and post-operative radiotherapy, 40 patients (Group B) with operation, post-operative radiotherapy, and QLR, 45 patients (Group C) were managed with concomitant chemoradiotherapy, 40 patients (Group D)with concomitant chemoradiation and QLR. QLR was given for 12 weeks. The radio- and chemotoxic reactions, quality of life (KPS score), and long-term efficacy (the recurrence time and the survival time) were observed. RESULTS: The toxicity levels were significantly lower in Group B than in Group A, manifested as radioactive dermatitis, mucositis, dysphagia, changes in body weight, and lymphatic edema (P < 0.05, P < 0.01). The toxicity levels were significantly lower in Group D than in Group C, manifested as radioactive dermatitis, mucositis, dysphagia, marrow depression, changes in body weight, and gastrointestinal reactions (P < 0.05, P < 0.01). After treatment the KPS scores of all patients obviously decreased (P < 0.05, P < 0.01). But the KPS scores were significantly higher in Group B than in Group A (P < 0.05), and they were significantly higher in Group D than in Group C (P < 0.05). The 3-year recurrence rate of patients in Group A was 41.94%, 20.00% in Group B, 60.00% in Group C, and 37.50% in Group D (P < 0.05). The 5-year survival rate of patients in Group A was 38.71%, 62.50% in Group B, 22.22% in Group C, and 42.50% in Group D (P < 0.05). CONCLUSIONS: QLR could effectively prevent and reduce the toxicity response caused by operation, radiotherapy and chemotherapy. The combination therapy of integrative medicine could postpone the recurrence and prolong the lifespan of patients. Therefore, we must not neglect the adjunctive therapy of QLR in treating hypopharyngeal carcinoma.
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Carcinoma de Células Escamosas/tratamento farmacológico , Medicamentos de Ervas Chinesas/uso terapêutico , Neoplasias Hipofaríngeas/tratamento farmacológico , Adolescente , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Quimioterapia Adjuvante , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fitoterapia , Resultado do Tratamento , Adulto JovemRESUMO
The mineralogical structure of flux films is a critical factor in controlling heat transfer in the mold and avoiding the longitudinal cracking of slabs during the continuous casting of peritectic steel. In this study, the layered structure, crystallization ratio, mineralogical species, and morphology features of flux films were characterized by optical microscopy, X-ray diffraction, and electron-probe microanalysis. Microstructural observation revealed that the normal flux films for peritectic steels present a multilayered structure and high crystallization ratio (60~90 vol%), mainly composed of well-developed crystalline akermanite and cuspidine. In contrast, the films with outstanding flux characteristics with abundant longitudinal cracks on the slab surface have a low crystallization ratio (<50 vol%) or vast crystallite content (>80 vol%). Furthermore, heat transfer analysis showed that the low crystallization ratio and the vast crystallite content of flux films worsen the heat transfer rate or uniformity in the mold, whereas the appropriate thickness and cuspidine content of flux films can improve the heat transfer performance. From the above results, it is concluded that using strong crystalline flux to obtain the ideal mineral phase structure of flux film is one of the important measures for reducing longitudinal cracks during continuous casting of peritectic steel slabs.
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In situ N-doped porous carbon (NPC) derived from wheat bran via a convenient salt sealing and air-assisted strategy was prepared for the removal of doxycycline (DOX) from aqueous solution. The NPC was precisely characterized by SEM, FTIR, XPS and BET analysis. Additionally, the experimental variables including contact time, adsorbent dosage of NPC and pH were optimized by using Box-Behnken design (BBD) under response surface methodology (RSM). The predicted adsorption capacity of DOX was found to be 291.14 mg g-1 under optimalizing experimental conditions of 196 min contact time, 0.2 g L-1 adsorbent dosage and pH 5.78. The adsorption experimental data fitted Langmuir, Koble-Corrigan and Redlich-Peterson models well, and the pseudo-second-order model perfectly described the DOX adsorption process onto NPC. Thermodynamic parameters of DOX adsorbed onto NPC indicated that the adsorption process was spontaneous and endothermic. Moreover, the adsorption of DOX on NPC was mostly controlled by electrostatic interaction, π-π electron-donator-acceptor (EDA) interaction, hydrogen-bonding and Lewis acid-base effect. Besides, the N element of NPC also played a role in capturing DOX. The maximum monolayer adsorption capacity of DOX was turn out to be 333.23 mg g-1 at 298 K, which suggested that the NPC could be a prospectively adsorbent for the removal of DOX from wastewater.
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Carbono , Poluentes Químicos da Água , Adsorção , Fibras na Dieta , Doxiciclina , Concentração de Íons de Hidrogênio , Cinética , Porosidade , Termodinâmica , Água , Poluentes Químicos da Água/análiseRESUMO
Cold stress limits plant growth and development; however, the precise mechanisms underpinning plant acclimation to cold stress remain largely unknown. In this study, the Ser/Thr protein kinase SOS2-LIKE PROTEIN KINASE5 (PKS5) was shown to play a positive role in plant responses to cold stress. A PKS5 loss-of-function mutant (pks5-1) exhibited elevated sensitivity to cold stress, as well as a lower survival rate and increased ion leakage. Conversely, PKS5 gain-of-function mutants (pks5-3, pks5-4) were more tolerant to cold stress and exhibited higher survival rates and decreased ion leakage. Stomatal aperture analysis revealed that stomatal closure was slower during the first 25 min after cold exposure in pks5-1 compared to wild-type, whereas pks5-3 and pks5-4 displayed accelerated stomatal closure over the same time period. Further stomatal aperture analysis under an abscisic acid (ABA) treatment showed slower closure in pks5-1 and more rapid closure in pks5-3 and pks5-4. Finally, expression levels of cold-responsive genes were regulated by PKS5 under cold stress conditions, while cold stress and ABA treatment can regulate PKS5 expression. Taken together, these results suggest that PKS5 plays a positive role in short-term plant acclimation to cold stress by regulating stomatal aperture, possibly via ABA pathways, and in long-term acclimation by regulating cold-responsive genes.
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Purpose: In social marketing, sharing reward program (SRP) is a common way to improve the marketing effect. However, few studies have explored the impact of consumers' self-presentation and face consciousness on enterprise SRP. This study aims to explore the influence of these two factors on the optimal SRP. Methods: A Stackelberg game between enterprises, sharers and potential consumers is developed to study the impact of sharers' face consciousness on enterprise's SRP. In order to discuss the impact of face consciousness on SRP in detail, we introduced status identity of commodity information, sharer's self-presentation preference and commodity price as exogenous variables in the research. Results: The results have shown that when the face consciousness of sharers is high, enterprises are advised to adopt the strategy of low reward and low requirement. But when the face consciousness is low, it would be better for them adopt the strategy of high reward and high requirement. In addition, with the low face consciousness, the optimal SRP is also affected by the relationship between the price of goods and the number of WeChat friends of sharers. Conclusion: The results suggest that when enterprises make incentive policies, considering consumers' self-presentation preference and face consciousness, the profit level can be effectively improved.
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Stomatal closure-associated actin-binding protein 1 (SCAB1) regulates stomatal closure by mediating actin filament reorganization in Arabidopsis thaliana. Our previous study showed that phosphatidylinositol 3-phosphate (PI3P) binds to SCAB1 and inhibits its oligomerization, thereby inhibiting its activity on F-actin in guard cells during stomatal closure. In this study, we show that another phospholipid, phosphatidic acid (PA), also binds to SCAB1 and inhibits its actin-bundling activity but not its actin-binding activity. F-actin bundling was promoted in vivo by treating Col-0 seedlings with n-butanol, a suppressor of PA production, but this effect was absent in the scab1 mutant. These results indicate that the signaling molecule PA is involved in the modulation of SCAB1 activity in F-actin reorganization.
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The adsorption potential of lotus leaf to remove methylene blue (MB) from aqueous solution was investigated in batch and fixed-bed column experiments. Langmuir, Freundlich, Temkin and Koble-Corrigan isotherm models were employed to discuss the adsorption behavior. The results of analysis indicated that the equilibrium data were perfectly represented by Temkin isotherm and the Langmuir saturation adsorption capacity of lotus leaf was found to be 239.6 mg g(-1) at 303 K. In fixed-bed column experiments, the effects of flow rate, influent concentration and bed height on the breakthrough characteristics of adsorption were discussed. The Thomas and the bed-depth/service time (BDST) models were applied to the column experimental data to determine the characteristic parameters of the column adsorption. The two models were found to be suitable to describe the dynamic behavior of MB adsorbed onto the lotus leaf powder column.
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Lotus/química , Azul de Metileno/química , Folhas de Planta/química , Adsorção , TermodinâmicaRESUMO
High salinity threatens crop production by harming plants and interfering with their development. Plant cells respond to salt stress in various ways, all of which involve multiple components such as proteins, peptides, lipids, sugars, and phytohormones. Phospholipids, important components of bio-membranes, are small amphoteric molecular compounds. These have attracted significant attention in recent years due to the regulatory effect they have on cellular activity. Over the past few decades, genetic and biochemical analyses have partly revealed that phospholipids regulate salt stress response by participating in salt stress signal transduction. In this review, we summarize the generation and metabolism of phospholipid phosphatidic acid (PA), phosphoinositides (PIs), phosphatidylserine (PS), phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG), as well as the regulatory role each phospholipid plays in the salt stress response. We also discuss the possible regulatory role based on how they act during other cellular activities.
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Plant metabolites are dynamically modified and distributed in response to environmental changes. However, it is poorly understood how metabolic change functions in plant stress responses. Maintaining ion homeostasis under salt stress requires coordinated activation of two types of central regulators: plasma membrane (PM) H+-ATPase and Na+/H+ antiporter. In this study, we used a bioassay-guided isolation approach to identify endogenous small molecules that affect PM H+-ATPase and Na+/H+ antiporter activities and identified phosphatidylinositol (PI), which inhibits PM H+-ATPase activity under non-stress conditions in Arabidopsis by directly binding to the C terminus of the PM H+-ATPase AHA2. Under salt stress, the phosphatidylinositol 4-phosphate-to-phosphatidylinositol (PI4P-to-PI) ratio increased, and PI4P bound and activated the PM Na+/H+ antiporter. PI prefers binding to the inactive form of PM H+-ATPase, while PI4P tends to bind to the active form of the Na+/H+ antiporter. Consistent with this, pis1 mutants, with reduced levels of PI, displayed increased PM H+-ATPase activity and salt stress tolerance, while the pi4kß1 mutant, with reduced levels of PI4P, displayed reduced PM Na+/H+ antiporter activity and salt stress tolerance. Collectively, our results reveal that the dynamic change between PI and PI4P in response to salt stress in Arabidopsis is crucial for maintaining ion homeostasis to protect plants from unfavorable environmental conditions.