Activity-stability trade-off observed in variants at position 315 of the GH10 xylanase XynR.

XynR is a thermostable alkaline GH10 xylanase, for which we have previously examined the effects of saturation mutagenesis at position 315 on enzyme alkaliphily, and found that at pH 10, the activities of variants could be ordered as follows: T315Q > T315S = T315N > T315H = wild-type XynR (WT) > 15 other variants. In this study, we sought to elucidate the mechanisms underlying the variable activity of these different variants. Crystallographic analysis revealed that the Ca2+ ion near position 315 in WT was absent in the T315Q variant. We accordingly hypothesized that the enhancement of alkaliphily in T315Q, and probably also in the T315H, T315N, and T315S variants, could be ascribed to an activity-stability trade-off associated with a reduction in stability due to the lack of this Ca2+ ion. Consistent with expectations, the alkaline resistance of T315H, T315N, T315Q, and T315S, evaluated through the pH-dependence of stability at 0 mM CaCl2 under alkaline conditions, was found to be lower than that of WT: the residual activity at pH 11 of WT was 78% while those of T315H, T315N, T315Q, and T315S were 0, 9, 0, and 43%, respectively. In addition, the thermostabilities of these four variants, as assessed using the denaturing temperatures (Tm) at 0 mM CaCl2 based on ellipticity at 222 nm in circular dichroism measurements, were lower than that of WT by 2-8 °C. Furthermore, the Tm values of WT and variants at 5 mM CaCl2 were higher than those at 0 mM CaCl2 by 6-11 °C. Collectively, our findings in this study indicate that mutation of the T residue at position 315 of XynR to H, N, Q, and S causes an increase in the alkaliphily of this enzyme, thereby reducing its stability.

Pps1, phosphatidylserine synthase, regulates the salt stress response in Schizosaccharomyces pombe.

Phosphatidylserine (PS) is important for maintaining growth, cytoskeleton, and various functions in yeast; however, its role in stress responses is poorly understood. In Schizosaccharomyces pombe, the PS synthase deletion (pps1∆) mutant shows defects in growth, morphology, cytokinesis, actin cytoskeleton, and cell wall integrity, and these phenotypes are rescued by ethanolamine supplementation. Here, we evaluated the role of Pps1 in the salt stress response in S. pombe. We found that pps1∆ cells are sensitive to salt stresses such as KCl and CaCl2 even in the presence of ethanolamine. Loss of the functional cAMP-dependent protein kinase (git3∆ or pka1∆) or phospholipase B Plb1 (plb1∆) enhanced the salt stress-sensitive phenotype in pps1∆ cells. Green fluorescent protein (GFP)-Pps1 was localized at the plasma membrane and endoplasmic reticulum regardless of the stress conditions. In pka1∆ cells, GFP-Pps1 was accumulated around the nucleus under the KCl stress. Pka1 was localized in the nucleus and the cytoplasm under normal conditions and transferred from the nucleus to the cytoplasm under salt-stress conditions. Pka1 translocated from the nucleus to the cytoplasm during CaCl2 stress in the wild-type cells, while it remained localized in the nucleus in pps1∆ cells. Expression and phosphorylation of Pka1-GFP were not changed in pps1∆ cells. Our results demonstrate that Pps1 plays an important role in the salt stress response in S. pombe.

High NaCl Concentrations in Water Are Associated with Developmental Abnormalities and Altered Gene Expression in Zebrafish.

Salt is frequently introduced in ecosystems, where it acts as a pollutant. This study examined how changes in salinity affect the survival and development of zebrafish from the two-cell to the blastocyst stage and from the blastocyst to the larval stage. Control zebrafish embryos were cultured in E3 medium containing 5 mM Sodium Chloride (NaCl), 0.17 mM Potassium Chloride (KCL), 0.33 mM Calcium Chloride (CaCl2), and 0.33 mM Magnesium Sulfade (MgSO4). Experiments were conducted using increasing concentrations of each individual salt at 5×, 10×, 50×, and 100× the concentration found in E3 medium. KCL, CaCl2, and MgSO4 did not result in lethal abnormalities and did not affect early embryo growth at any of the concentrations tested. Concentrations of 50× and 100× NaCl caused embryonic death in both stages of development. Concentrations of 5× and 10× NaCl resulted in uninflated swim bladders in 12% and 65% of larvae, compared to 4.2% of controls, and caused 1654 and 2628 genes to be differentially expressed in blastocysts, respectively. The ATM signaling pathway was affected, and the Sonic Hedgehog pathway genes Shh and Ptc1 implicated in swim bladder development were downregulated. Our findings suggest that increased NaCl concentrations may alter gene expression and cause developmental abnormalities in animals found in affected ecosystems.

[Effect of asiaticoside on systolic blood pressure and relaxation of isolated thoracic aorta of rats].

OBJECTIVE: To investigate the effect of asiaticoside on blood pressure and relaxation of thoracic aorta in rats and explore the underlying mechanism. METHODS: SD rats treated with 50 and 100 mg/kg asiaticoside by daily gavage for 2 weeks were monitored for systolic blood pressure changes, and histological changes of the thoracic aorta were evaluated using HE staining. In isolated rat endothelium-intact and endothelium-denuded thoracic aorta rings, the effects of asiaticoside on relaxation of the aortic rings were tested at baseline and following norepinephrine (NE)- and KCl-induced constriction. The vascular relaxation effect of asiaticoside was further observed in NE-stimulated endothelium-intact rat aortic rings pretreated with L-nitroarginine methyl ester, indomethacin, zinc protoporphyrin Ⅸ, tetraethyl ammonium chloride, glibenclamide, barium chloride, Iberiotoxin, 4-aminopyridine, or TASK-1-IN-1. The aortic rings were treated with KCl and NE followed by increasing concentrations of CaCl2 to investigate the effect of asiaticoside on vasoconstriction induced by external calcium influx and internal calcium release. RESULTS: Asiaticoside at 50 and 100 mg/kg significantly lowered systolic blood pressure in rats without affecting the thoracic aorta histomorphology. While not obviously affecting resting aortic rings with intact endothelium, asiaticoside at 100 mg/kg induced significant relaxation of the rings constricted by KCl and NE, but its effects differed between endothelium-intact and endothelium-denuded rings. In endothelium-intact aortic rings pretreated with indomethacin, ZnPP Ⅸ, barium chloride, glyburide, TASK-1-IN-1 and 4-aminopyridine, asiaticoside did not produce significant effect on NE-induced vasoconstriction, and tetraethylammonium, Iberiotoxin and L-nitroarginine methyl ester all inhibited the relaxation effect of asiaticoside. In KCland NE-treated rings, asiaticoside obviously inhibited CaCl2-induced vascular contraction. CONCLUSION: Asiaticoside induces thoracic aorta relaxation by mediating high-conductance calcium-activated potassium channel opening, promoting nitric oxide release from endothelial cells and regulating Ca2+ influx and outflow, thereby reducing systolic blood pressure in rats.

Effect of sheep bone protein hydrolysate on promoting calcium absorption and enhancing bone quality in low-calcium diet fed rats.

Calcium deficiency is prone to fractures, osteoporosis and other symptoms. In this study, sheep bone protein hydrolysates (SBPHs) were obtained by protease hydrolysis. A low-calcium-diet-induced calcium-deficiency rat model was established to investigate the effects of SBPHs on calcium absorption and intestinal flora composition. The results showed that an SBPHs + CaCl2 treatment significantly increased the bone calcium content, bone mineral density, trabecular bone volume, and trabecular thickness, and reduced trabecular separation, and changed the level of bone turnover markers (P < 0.05). Supplementation of SBPHs + CaCl2 can remarkably enhance the bone mechanical strength, and the microstructure of bone was improved, and the trabecular network was more continuous, complete, and thicker. Additionally, SBPHs + CaCl2 dietary increased the abundance of Firmicutes and reduced the abundance of Proteobacteria and Verrucomicrobiota, and promoted the production of short chain fatty acids. This study indicated that SBPHs promoted calcium absorption and could be applied to alleviate osteoporosis.

The effect of three additives on properties of mineral trioxide aggregate cements: a systematic review and meta-analysis of in vitro studies.

BACKGROUND: Several efforts have been made to improve mechanical and biological properties of calcium silicate-based cements through changes in chemical composition of the materials. This study aimed to investigate the physical (including setting time and compressive strength) and chemical (including calcium ion release, pH level) properties as well as changes in cytotoxicity of mineral trioxide aggregate (MTA) after the addition of 3 substances including CaCl2, Na2HPO4, and propylene glycol (PG). METHODS: The systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Electronic searches were performed on PubMed, Embase, and Scopus databases, spanning from 1993 to October 2023 in addition to manual searches. Relevant laboratory studies were included. The quality of the included studies was assessed using modified ARRIVE criteria. Meta-analyses were performed by RevMan statistical software. RESULTS: From the total of 267 studies, 24 articles were included in this review. The results of the meta-analysis indicated that addition of PG increased final setting time and Ca2+ ion release. Addition of Na2HPO4 did not change pH and cytotoxicity but reduced the final setting time. Incorporation of 5% CaCl2 reduced the setting time but did not alter the cytotoxicity of the cement. However, addition of 10% CaCl2 reduced cell viability, setting time, and compressive strength. CONCLUSION: Inclusion of 2.5% wt. Na2HPO4 and 5% CaCl2 in MTA can be advisable for enhancing the physical, chemical, and cytotoxic characteristics of the admixture. Conversely, caution is advised against incorporating elevated concentrations of PG due to its retarding effect. TRIAL REGISTRATION: PROSPERO registration number: CRD42021253707.

CO2 sequestration in microbial electrolytic cell-anaerobic digestion system combined with mineral carbonation for sludge hydrolysate treatment.

The combination of microbial electrolytic cells and anaerobic digestion (MEC-AD) became an efficient method to improve CO2 capture for waste sludge treatment. By adding CaCl2 and wollastonite, the CO2 sequestration effect with mineral carbonation under 0 V and 0.8 V was studied. The results showed that applied voltage could increase dissolved chemical oxygen demand (SCOD) degradation efficiency and biogas yield effectively. In addition, wollastonite and CaCl2 exhibited different CO2 sequestration performances due to different Ca2+ release characteristics. Wollastonite appeared to have a better CO2 sequestration effect and provided a wide margin of pH change, but CaCl2 released Ca2+ directly and decreased the pH of the MEC-AD system. The results showed methane yield reached 137.31 and 163.50 mL/g SCOD degraded and CO2 content of biogas is only 12.40 % and 2.22 % under 0.8 V with CaCl2 and wollastonite addition, respectively. Finally, the contribution of chemical CO2 sequestration by mineral carbonation and biological CO2 sequestration by hydrogenotrophic methanogenesis was clarified with CaCl2 addition. The chemical and biological CO2 sequestration percentages were 46.79 % and 53.21 % under 0.8 V, respectively. With the increased applied voltage, the contribution of chemical CO2 sequestration rose accordingly. The findings in this study are of great significance for further comprehending the mechanism of calcium addition on CO2 sequestration in the MEC-AD system and providing guidance for the later engineering application.

Exceptional anti-toxic growth of water spinach in arsenic and cadmium co-contaminated soil remediated using biochar loaded with Bacillus aryabhattai.

Functionalized biochars are crucial for simultaneous soil remediation and safe agricultural production. However, a comprehensive understanding of the remediation mechanism and crop safety is imperative. In this work, the all-in-one biochars loaded with a Bacillus aryabhattai (B10) were developed via physisorption (BBC) and sodium alginate embedding (EBC) for simultaneous toxic As and Cd stabilization in soil. The bacteria-loaded biochar composites significantly decreased exchangeable As and Cd fractions in co-contaminated soil, with enhanced residual fractions. Heavy metal bioavailability analysis showed a maximum CaCl2-As concentration decline of 63.51% and a CaCl2-Cd decline of 50.96%. At a 3% dosage of composite, rhizosphere soil showed improved organic matter, cation exchange capacity, and enzyme activity. The aboveground portion of water spinach grown in pots was edible, with final As and Cd contents (0.347 and 0.075 mg·kg⁻¹, respectively) meeting food safety standards. Microbial analysis revealed the composite's influence on the rhizosphere microbial community, favoring beneficial bacteria and reducing plant pathogenic fungi. Additionally, it increased functional microorganisms with heavy metal-resistant genes, limiting metal migration in plants and favoring its growth. Our research highlights an effective strategy for simultaneous As and Cd immobilization in soil and inhibition of heavy metal accumulation in vegetables.

Isolation and quantification of alginate in choline chloride-based deep eutectic solvents.

Extraction of seaweed compounds using Deep Eutectic Solvents (DES) has shown high interest. Quantification, however, is challenging due to interactions with DES components. In this research work, three chemical separation techniques were investigated to isolate and quantify alginate from a set of choline chloride-based DES. While choline chloride served as the hydrogen bond acceptor (HBA); Urea, Ethylene Glycol, Propylene Glycol, Glycerol, Sorbitol, Xylitol and Glucose were used as hydrogen bond donors (HBD). DES containing sodium alginate were subjected to precipitation with sulfuric acid 0.2 M (pH 1.6), ethanol-water mixture (80 % v/v) and calcium chloride (1 % w/v CaCl2·2H2O). Alginate in precipitates was quantified and used to evaluate the performance of each separation technique. The highest recovery yields (51.2 ± 1.3 %) were obtained using the ethanol-water mixture followed by calcium chloride (45.7 ± 1.2 %), except for polyols (e.g. sorbitol). The lowest recovery yields were obtained with acid, with a particularly low recovery yield when urea was used as HBD (9.6 ± 1.3 %). Estimations of ManA/GulA ratios showed lower values for precipitates from DES compared to the ones obtained from water. This research shows ethanolic precipitation as a suitable method for alginate separation from the studied set of choline chloride-based DES.

Hypertonic Aerosols Hydrate Airways Longer and Reduce Acidification Risk with Nonpermeating Cation and Permeating Anion Salts.

Background: Hyperosmolar aerosols appear to promote or suppress upper airway dysfunction caused by dehydration in a composition-dependent manner. We sought to explore this composition dependence experimentally, in an interventional human clinical study, and theoretically, by numerical analysis of upper airway ion and water transport. Methods: In a double-blinded, placebo-controlled clinical study, phonation threshold pressure (PTP) was measured prenasal and postnasal inhalation of hypertonic aerosols of NaCl, KCl, CaCl2, and MgCl2 in seven human subjects. Numerical analysis of water and solute exchanges in the upper airways following deposition of these same aerosols was performed using a mathematical model previously described in the literature. Results: PTP decreased by 9%-22% relative to baseline (p < 0.05) for all salts within the first 30 minutes postadministration, indicating effective laryngeal hydration. Only MgCl2 reduced PTP beyond 90 minutes (21% below baseline at 2 hours postadministration). By numerical analysis, we determined that, while airway water volume up to 15 minutes postdeposition is dictated by osmolarity, after 30 minutes, divalent cation salts, such as MgCl2, better retain airway surface liquid (ASL) volume by slow paracellular clearance of the divalent cation. Fall of CFTR chloride flux with rise in ASL height, a promoter of airway acidification, appears to be a signature of permeating cation (NaCl) and nonpermeating anion (mannitol) aerosol deposition. For hypertonic aerosols that lack permeating cation and include permeating anion (CaCl2 and MgCl2), this acid-trigger signature does not exist. Conclusions: Nonpermeating cation and permeating anion hypertonic aerosols appear to hydrate upper airways longer and, rather than provoke, may reduce laryngeal dysfunction such as cough and bronchoconstriction.

Gelation of crocodile myofibrillar protein - κ-carrageenan mixtures in two low-NaCl solution.

Crocodile meat is a novel reptile meat source, but its processing method is rare. This study investigated the effect of κ-carrageenan addition and partial substitution of NaCl on the gel properties of crocodile myofibrillar protein (CMP). Result showed that CMP formed gel when temperature above 60 ℃. The water-holding capacity, gel strength, denaturation degree, sulfhydryl content covalent bond and hydrophobic bond of gel in KCl solution were significantly higher than those in CaCl2 solution (P < 0.05). K+ induced CMP to form a tight network structure with uniform small pores though covalent and hydrophobic bonds, but the gel properties were reduced by κ-carrageenan. In CaCl2 solution, κ-carrageenan improved the gel structure by filling the protein network through hydrogen bonding. Therefore, it can be concluded that KCl is better than CaCl2 in the manufacturing of low-sodium crocodile foods. Moreover, κ-carrageenan was only beneficial to gel quality in CaCl2 solution.

Enhancing soil redox dynamics: Comparative effects of Fe-modified biochar (N-Fe and S-Fe) on Fe oxide transformation and Cd immobilization.

Biochar and modified biochar have gained wide attention for Cd-contaminated soil remediation. This study investigates the effects of rape straw biochar (RSB), sulfur-iron modified biochar (S-FeBC), and nitrogen-iron modified biochar (N-FeBC) on soil Fe oxide transformation and Cd immobilization. The mediated electrochemical analysis results showed that Fe modification effectively enhanced the electron exchange capacity (EEC) of biochar. After 40 days of anaerobic incubation, compared to the treatment without biochar (CK), the concentrations of CaCl2-extractable Cd in N-FeBC, S-FeBC, and RSB treatments decreased by 79%, 53%, and 23%, respectively. Compared with S-FeBC, N-FeBC significantly decreased the soil Eh and increased soil pH within the first 15 days, which could be attributed to its higher EEC and alkalinity. There is a negative correlation between the concentration of CaCl2-extractable Cd and soil pH (p < 0.01). The sequential extraction results showed that both N-FeBC and S-FeBC promoted Cd transfer from acid-soluble to Fe/Mn oxides bound fraction (Fe/Mn-Cd). N-FeBC significantly increased the concentration of amorphous Fe oxides (amFeox) from 4.0 g kg-1 in day 1 to 4.6 g kg-1 in day 15 by promoting the NO3--reducing Fe(II) oxidation process, while S-FeBC significantly increased amFeox from 4.0 g kg-1 in day 15 to 4.8 g kg-1 in day 40 by promoting the Fe(II) recrystallization. There is a positive correlation between the concentration of amFeox and Fe/Mn-Cd (p < 0.01). The scanning electron microscopy analysis showed that Cd was bound to the amFeox coating on the surface of Fe-modified biochar. By acting as an electron shuttle, the active surface of Fe-modified biochar may serve as a hotspot for Fe transformation, which promotes amFeox formation and Cd immobilization. This study highlights the potential of Fe-modified biochar for the remediation of Cd-contaminated soils and provides valuable insights into the development of effective remediation approaches for Cd-contaminated soils.

Rapid assessment of soil accessible Cr(â ¥) in the field by a portable RGB color sensor.

Field rapid determination of soil accessible Cr(Ⅵ) is of great significance for on-site assessment and decision-making about the health risks of contaminated sites. When the thickness of solutions with various concentrations of Cr(Ⅵ) is constant, there would be a quantitative relationship between the chromogenic difference of Cr(Ⅵ) solutions and the concentration of Cr(Ⅵ). The chromogenic difference could be described by Red (R), Green (G), Blue (B) values. Based on the chromogenic reaction between 1,5-diphenylcarbazide and Cr(Ⅵ), this study first established the calibration curve between the chromogenic difference and the concentration of Cr(Ⅵ) in standard solution with or without 0.01 M CaCl2, using an RGB color sensor. This is the subsequent determination basis of the method for rapidly assessing accessible Cr(Ⅵ) in the field (M-RGB). Then, the concentration of accessible Cr(Ⅵ) of contaminated soil with "hand-shaking + standing" field extraction method was compared with "end-over-end shaking" laboratory extraction method. Finally, the accessible Cr(Ⅵ) of contaminated soil extractants was determined via M-RGB integrating the field extraction method. Results indicated there was a highly significant linear relationship between colorimetric difference value (∆E) and Cr(Ⅵ) concentration in the range of 0.1-3 mg/L (R2 > 0.99, P < 0.01), based on the Euclidean formula for calculating ∆E. The "hand-shaking + standing" field extraction method was effective in obtaining accessible Cr(Ⅵ) extractants with or without 0.01 M CaCl2, with the high extraction efficiency within 100±1%. The concentrations of accessible Cr(Ⅵ) in various polluted soils determined by M-RGB were consistent with that determined by the ultraviolet-visible spectrophotometry, with the relative error within ±5%, and the relative standard deviation ≤ 20%. The spiked recovery experiments showed that the recovery of M-RGB was between 95% and 105%, which means M-RGB could realize the trace analysis for accessible Cr(Ⅵ) in the field.

Effect of magnetic field mediated CaCl2 on the edible quality of low-sodium minced pork gels.

Magnetic field combined with calcium chloride (CaCl2,) treatment is a highly promising technique for reducing sodium chloride (NaCl) in meat. Therefore, this paper investigated the effect of reducing NaCl addition (0-10%) by CaCl2 in combination with a magnetic field (3.8 mT) on the edible quality of low-salt pork mince. It is desired to drive the application of magnetic field and CaCl2 in low-sodium meat processing in this way. Results showed that the cooking yield, color, hardness, elasticity, mouthfeel, apparent texture, and orderliness of protein conformation of all minced pork were improved as compared to the control group, while the electron nose response values of their volatile sulfides and nitrogen oxides were decreased. In particular, the best edible quality and perceived salty intensity of minced pork gel was obtained by using CaCl2 in place of 5% NaCl under magnetic field mediation. In addition, energy dispersive X-ray spectroscopy scans showed that the reduced NaCl treatment by magnetic field combined with CaCl2 could increase the signal intensity of sodium in minced pork matrices to some extent. Magnetic field-mediated substitution of NaCl for CaCl2 treatment was also found to be favorable for inducing the transition of the protein secondary structure from an irregularly coiled to a ß-folded structure (demonstrated by infrared spectroscopy). In short, magnetic fields combined with CaCl2 instead of NaCl was a highly promising method of producing low-NaCl meats.

Saline extraction assisted by ultrasound: a method to obtain purified phycocyanin.

The influence of ultrasound intensity and saline solution concentration (NH4Cl and CaCl2) on phycocyanin extraction from Arthrospira platensis was evaluated. The intensity had a significant effect on phycocyanin content and purity, while the saline solution concentration only had an effect on purity. The optimum extraction condition was obtained at 41% of intensity and 8.5 g.L-1 of CaCl2 solution. In this condition, ultrasound promoted cell disruption efficiently, increasing the extraction yield. The combination of ultrasound with CaCl2 solution reduced the co-extraction of chlorophylls and other proteins, providing more purified extracts. The freezing and thawing method was compared to the best condition obtained, and it showed no significant difference for phycocyanin content but better results for purity. Overall, ultrasound treatment may be considered a promising technology to obtain phycocyanin by the food industry without additional purification techniques due to the reduced extraction time, less use of energy, and easy scale-up.

Carboxymethyl hydroxypropyl guar gum physicochemical properties in dilute aqueous media.

We investigate carboxymethyl hydroxypropyl guar gum (CMHPG) solution properties in water and NaCl, KCl, and CaCl2 aqueous solutions. The Huggins, Kraemer, and Rao models were applied by fitting specific and relative viscosity of CMHPG/water and CMHPG/salt/water to determine the intrinsic viscosity [η]. The Rao models yielded better results (R2 = 0.779-0.999) than Huggins and Kraemer equations. [η] decreased up to 84% in salt solution over the range 0.9-100 mM compared to water. Salt effects screened the CMHPG charged side groups chains leading to a compacted structure. In 0.9 mM NaCl(aq), the hydrodynamic coil radius (Rcoil) was 28% smaller and 45% smaller in 100 mM NaCl solution relative to water. Similar decreases were seen in KCl and CaCl2 solutions. KCl and CaCl2 were more effective than NaCl. CMHPG is salt-tolerant and shows comparatively less viscosity change than native guar gum, with modest reduced viscosity increases with CMHPG dilution at all salt concentrations. The electrostatic interactions were effective up to 100 mM salt. The activation energy of viscous flow for CMHPG solutions was computed and compared to measured xanthan gum and several literature values. These data show that the barrier to CMHPG flow is higher than for xanthan gum.

Effect of experimental boundary conditions and treatment-time on the electro-desalination of soils.

This study investigates the effect of boundary conditions and treatment-time on the electro-desalination of artificially-contaminated soil. The effect of ion exchange membranes (IEM), calcium chloride (CaCl2), and ethylenediaminetetraacetic acid (EDTA) on the removal of salt (i.e., Na+, Cl-, and Ca2+) and metal (i.e., Co2+ and Fe2+) ions from the soil by electrokinetic (EK) was studied. The outcomes demonstrate that an increase in treatment-time decreases the electroosmosis and ion removal rate, which might be attributed to the formation of acid-base fronts in soil, except in the IEM case. Because a high pH jump and electroosmotic flow (EOF) of water were not observed within the soil specimen due to the IEM, the removal of ions was only by diffusion and electromigration. The collision of acid-base fronts produced a large voltage gradient in a narrow soil region with a reduced electric field (EF) in its remaining parts, causing a decrease in EOF and ion transport by electromigration. The results showed that higher electroosmosis was observed by using CaCl2 and EDTA; thus, the removal rate of Co2+, Na+, and Ca2+ was greater than Cl- due to higher EOF. However, for relatively low EOF, the removal of Cl- exceeded that of Co2+, Na+, and Ca2+, possibly due to a lack of EOF. In addition, the adsorption of Fe2+ in soil increased with treatment-time due to the corrosion of the anode during all EK experiments except in the case of IEM, where an anion exchange membrane (AEM) was introduced at the anode-soil interface.

Alleviating summer heat stress in cowpea-baby corn intercropping with stress-reducing chemicals and fertility variations.

Over the past century, the average surface temperature and recurrent heatwaves have been steadily rising, especially during the summer season, which is affecting the yield potential of most food crops. Hence, diversification in cropping systems with suitable fertilizer management is an urgent need to ensure high yield potential during the summer season. Since intercropping has emerged as an important strategy to increase food production, the present study comprises five intercropping systems in the main plot (sole cowpea, sole baby corn, cowpea + baby corn in 2:1, 3:1, and 4:1 row ratio), three levels of fertilizer viz. 100 (N20 P40), 125 (N25 P50), and 150% (N30 P60) recommended dose of fertilizer (RDF) in the subplot, along with two stress-mitigating chemicals (0.5% CaCl2 and 1% KNO3) in the sub-sub plots. A split-split plot system with four replications was established to carry out the field experiment. The effect of intercropping, fertilizer levels, and stress-mitigating chemicals on crop growth rate (CGR), relative growth rate (RGR), plant temperature, relative water content (RWC) and chlorophyll content of cowpea and baby corn, as well as cowpea equivalent yield (CEY), was investigated during the summer seasons of 2019 and 2020. The experiment was conducted at Agriculture University, Kota (Rajasthan), India. Results showed that CGR, RGR, RWC and chlorophyll content of both crops and CEY were maximum under intercropping of cowpea and baby corn in a 2:1 row ratio compared to other intercropping systems. However, the plant temperature of both crops was significantly lower under this system. CEY, CGR, RGR, and chlorophyll content were considerably greater in the subplots with a fertilizer application of 150% RDF compared to lower levels of fertilizer (100 and 125% RDF). Our findings further show that foliar application of CaCl2 0.5% at the flowering and pod-developing stages of cowpea dramatically boosted CEY, CGR, RGR, RWC, and chlorophyll content of both crops and lowered the plant temperature.

Enhancement of yellow pigments production via high CaCl2 stress fermentation of Monascus purpureus.

Monascus pigments (MPs) are a kind of natural ingredient fermented by Monascus spp., which contains three types of pigments: red, orange, and yellow ones. Monascus yellow pigments have a restricted yield and cannot meet industrial application. The method and mechanism of CaCl2 improving yellow pigments production by liquid fermentation of Monascus purpureus M8 were studied in order to overcome the low yield of yellow pigments produced by liquid fermentation. Changes in physiological and biochemical indicators explained the effects of CaCl2 on the production of Monascus yellow pigments from solid fermentation. The intracellular yellow pigments, orange pigments, and red pigments increased by 156.08%, 43.76%, and 42.73%, respectively, with 60 g/l CaCl2 addition to culture medium. The amount of red and orange pigments reduced, while the proportion of yellow pigments increased and the relative peak area of intracellular yellow pigments accounted for a dominant 98.2%, according to thin layer chromatography and high performance liquid chromatography analyses. Furthermore, the influence of CaCl2 extended to the modulation of pigments synthesis-related gene expression in M8 strain. This modulation led to a pronounced upregulation in the expression of the yellow pigments synthesis-related gene, mppE, signifying a pivotal role played by CaCl2 in orchestrating the intricate machinery behind yellow pigments biosynthesis.

Amelioration of NaCl stress on germination, growth, and nitrogen fixation of Vicia faba at isosmotic Na-Ca combinations and Rhizobium.

MAIN CONCLUSION: The Na+/Ca2+ ratio of 1/5 ameliorated the inhibitory action of NaCl and improved the germination and growth of Vicia faba. Addition of Rhizobium also enhanced nodulation and nitrogen fixation. Casting light upon the impact of salinity stress on growth and nitrogen fixation of Vicia faba supplemented with Rhizobium has been traced in this work. How Ca2+ antagonizes Na+ toxicity and osmotic stress of NaCl was also targeted in isosmotic combinations of NaCl and CaCl2 having various Na+:Ca2+ ratios. Growth of Vicia faba (cultivar Giza 3) was studied at two stages: germination and seedling. At both experiments, seeds or seedlings were exposed to successively increasing salinity levels (0, 50, 100, 150, and 200 mM NaCl) as well as isosmotic combinations of NaCl and CaCl2 (Na+:Ca2+ of 1:1, 1:5, 1:10, 1:15, 1:18, and 1: 20), equivalent to 150 mM NaCl. Inocula of the local nitrogen-fixing bacteria, Rhizobium leguminosarum (OP715892) were supplemented at both stages. NaCl salinity exerted a negative impact on growth and metabolism of Vicia faba; inhibition was proportional with increasing salinity level up to the highest level of 200 mM. Seed germination, shoot and root lengths, fresh and dry weights, chlorophyll content, and nodules (number, weight, leghemoglobin, respiration, and nitrogenase activity) were inhibited by salinity. Ca2+ substitution for Na+, particularly at a Na/Ca ratio of 1:5, was stimulatory to almost all parameters at both stages. Statistical correlations between salinity levels and Na/Ca combinations proved one of the four levels (strong- or weak positive, strong- or weak negative) with most of the investigated parameters, depending on the parameter.