Total Mg2 Research Articles

Characterization of intestine-specific TRPM6 knockout C57BL/6J mice: effects of short-term omeprazole treatment.

The transient receptor potential melastatin type 6 (TRPM6) is a divalent cation channel pivotal for gatekeeping Mg2+ balance. Disturbance in Mg2+ balance has been associated with the chronic use of proton pump inhibitors (PPIs) such as omeprazole. In this study, we investigated if TRPM6 plays a role in mediating the effects of short-term (4days) omeprazole treatment on intestinal Mg2+ malabsorption using intestine-specific TRPM6 knockout (Vill1-TRPM6-/-) mice. To do this, forty-eight adult male C57BL/6J mice (50% TRPM6fl/fl and 50% Vill1-TRPM6-/-) were characterized, and the distal colon of these mice was subjected to RNA sequencing. Moreover, these mice were exposed to 20mg/kg bodyweight omeprazole or placebo for 4days. Vill1-TRPM6-/- mice had a significantly lower 25Mg2+ absorption compared to control TRPM6fl/fl mice, accompanied by lower Mg2+ serum levels, and urinary Mg2+ excretion. Furthermore, renal Slc41a3, Trpm6, and Trpm7 gene expressions were higher in these animals, indicating a compensatory mechanism via the kidney. RNA sequencing of the distal colon revealed a downregulation of the Mn2+ transporter Slc30a10. However, no changes in Mn2+ serum, urine, and feces levels were observed. Moreover, 4days omeprazole treatment did not affect Mg2+ homeostasis as no changes in serum 25Mg2+ and total Mg2+ were seen. In conclusion, we demonstrate here for the first time that Vill1-TRPM6-/- mice have a lower Mg2+ absorption in the intestines. Moreover, short-term omeprazole treatment does not alter Mg2+ absorption in both Vill1-TRPM6-/- and TRPM6fl/fl mice. This suggests that TRPM6-mediated Mg2+ absorption in the intestines is not affected by short-term PPI administration.

Magnesium matters: unveiling hidden risks in kidney transplant patients through total and ionized magnesium profiling.

In kidney transplant (KT) patients, magnesium (Mg2+) deficiency is widespread. It is often encountered early after KT, may persist longer, and is frequently promoted by calcineurin inhibitors (CNIs) and tubular leakage. Studies demonstrated an association between post-KT hypomagnesemia and allograft dysfunction. The concentration of the active form, the ionized Mg2+ (iMg2+), is not measured clinically, and total Mg2+ (tMg2+) and iMg2+ correlations are conflicting. We assess the cross-sectional prevalence of hypomagnesemia in KT patients. The correlation of demographic and anthropometric parameters was also studied. A prospective, single-center analysis of KT patients was conducted at the University Hospital of Bern, Switzerland (March 2023-August 2023). Blood samples were collected at least twice for the majority of patients. tMg2+ has been quantified from a plasma sample at the Clinical Chemistry Department of the University Hospital of Bern. The PRIME® ES analyzer (Nova Biomedical, USA) provided results for iMg2+. The following co-variables were considered: age, comorbidities, kidney disease, KT history, estimated glomerular filtration rate (eGFR), and treatment (including Mg2+ supplementation and immunosuppression). A total of 208 measurements in 104 patients were performed [once in 9/104 patients (8.7%), twice in 86/104 (82.7%), and three times in 9/104 (8.7%)]. Compared to that in healthy volunteers (51 measurements in 51 participants), mean iMg2+ was significantly lower in KT patients {KT: 0.46 mmol/L [interquartile range (IQR): 0.40-0.50], volunteers: 0.57 mmol/L (IQR 0.54-0.61), p < 0.01}. Overall, iMg2+ and tMg2+ showed strong category agreement (r2 = 0.93, p < 0.01). In linear regression, low iMg2+ correlated with CNI exposure. For 110/208 measurements (52.9%), a reduced iMg2+ (cutoff: 0.42 mmol/L) was shown. In 58/208 (27.9%), both values were reduced, and 52/208 (25%) had isolated reduced iMg2+. In principal component analysis, patients with isolated low iMg2+ clustered with patients with low iMg2+ and tMg2+. iMg2+ and tMg2+ were strongly correlated. A substantial proportion of patients show isolated low iMg2+. Currently, it is unclear if these patients suffer from Mg2+ deficiency.

Comprehensive environmental impact assessment and irrigation wastewater suitability of the Arab El-Madabegh wastewater treatment plant, ASSIUT CITY, EGYPT.

The presence of a wastewater treatment plant in the Arab El-Madabegh region, which discharges excessive amounts of raw effluent toward the nearby farming fields, is the area's main issue. Examining the harmful implications of raw effluent releases on groundwater quality, determining if treated wastewater effluent complies with regulations for discharge into the aquatic environment, and assessing irrigation appropriateness by the effluent are the main goals of this work. In order to accomplish these targets, twelve treated effluent samples from the Arab El-Madabegh wastewater treatment plant were gathered every two weeks starting in January 2012 and finishing in June 2012. They were tested to determine pH, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Temperature (Temp), Conductivity (EC), Turbidity (Turb.), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Organic Carbon (TOC), NO3-, SO42-, Cl-, Ca2+, PO43-, HCO3-, Na+, Mg2+, and heavy metals such as (Fe, Mn, K+, Cr, Pb, Zn, Ni, Cu, and Cd). The outcomes revealed that all Egyptian and Food and Agricultural Organization (FAO) standards for unrestricted irrigation were met by the treated effluents, except for COD, which exceeded than the Egyptian allowed limit. The evaluation indices of the effluent's EC, SAR, PI, MR, and MH were in the low-risk category according to indicators of water quality for irrigation, nevertheless, The SSP and RSC both showed slightly higher values (67.9% and 2.76, respectively). As well, The average values of heavy metals in treated wastewater effluent were found to be below permitted limits, with the exception of lead and phosphate, which exceeded permissible limits in Egypt. The environmental sustainability (ecological friendliness) of reusing and recycling tertiary treated wastewater can be achieved in agriculture to reduce the adverse impacts on the aquatic environment.

The effects of prolonged stress exposure on the brain of rats and insights to understand the impact of work-related stress on caregivers

IntroductionStress exposure is a significant concern in the healthcare sector. This animal model study aims to reproduce caregivers’ working conditions and determine their impact on the brain.MethodTwenty-four healthy male rats of the Wistar strain were divided into four groups. Three groups were submitted each to one stressor for 21 days, while the fourth group was used as a control. Stressors were food and water deprivation (FW), permanent illumination (PI), and forced swimming (FS). At the end of the experiment, rats were euthanized, and stress biomarkers, biological parameters, and DNA damage were measured.ResultsProoxidant biomarker rates increased in the different groups (+50 to +75%) compared to the control (p &amp;lt; 0.0001). Urinary corticosterone rates increased in all stressed animals, mainly in the PI group, with changes of up to +50% compared to the control group. Acetylcholinesterase levels decreased to −50% (p &amp;lt; 0.0001 for the three exposed groups). Total ATPase, (Na+/K+)-ATPase, and Mg2+-ATPase activities decreased in all stressed groups. The percentage of brain cell congestion and apoptosis was 3% for the FW group (p &amp;lt; 0.0001), 2% for the PI group (p &amp;lt; 0.0001), and 4% for the FS group (p &amp;lt; 0.0001) compared to the control (0.8%). DNA damage was observed in all exposed groups. Finally, we noticed behavioral changes and a depression-like syndrome in all stressed rats.ConclusionStressful conditions such as the working environment of caregivers can trigger several pathophysiological processes leading to oxidative, neurochemical, and hypothalamic–pituitary–adrenal disorders. These changes can progress to cell damage and apoptosis in the brain and trigger psychological and physical disorders.

Risk assessment for the distribution and levels of fluoride and nitrate in groundwater in a semi-arid area of northern Mexico

This study assessed groundwater quality and associated risks in a semi-arid region located in a city in the Northern zone of Mexico. To conduct this study, we collected 92 groundwater samples and analyzed 14 physicochemical parameters across 18 sectors. Only fluoride (F−) and nitrate (NO3–N) exceeded Mexican regulations and WHO guidelines for drinking water. Approximately 65 % of samples surpassed the 1.5 mg/L permissible limit for F−, with the highest recorded concentration reaching 3.60 mg/L in two sectors among the 18 studied, 34 % of samples exhibited NO3−-N concentrations in the 10.64–17.27 mg/L range across three sectors, surpassing permissible levels. Pearson Correlation Analysis revealed strong positive correlations with HCO3−, EC, Mg2+, Ca2+, NO3−, Cl−, SO42−, and Na+. Moderate correlations existed for the total hardness, alkalinity, Cl−, NO3−, SO42−, Na+, Mg2+, and EC. K+ showed weak correlations. PIG values indicated significant pollution of F− in all of 18 sectors (PIG <1). HQ for F− exceeded tolerable levels in 14 adult and 16 child sectors, posing an intolerable risk. Nitrate's HQ was below <1 for all age groups, suggesting non-carcinogenic effects. THI indicated high F− and NO3−-N exposure risks for children in the study area. It is recommended to implement effective water treatment technologies, such as reverse osmosis or adsorptive materials, in those sectors reported as a potential risk to human health to ensure access to safe drinking water.

Water and salt recovery from shale gas produced water by vacuum membrane distillation followed by crystallization

A vacuum membrane distillation (VMD) followed by crystallization (VMD-C) was developed for the recovery of water and salts from shale gas produced water (SGPW). Before VMD, the pretreatment of SGPW with Fenton oxidation-flocculation is applied, with the chemical oxygen demand (COD) concentration reduction of 75% and the total removal of the total suspended solids (TSS), Ca2+, and Mg2+ in SGPW. The pretreatment of SGPW mitigated the membrane fouling in the VMD and effectively prevented the reduction of membrane flux over time. The average flux of the PTFE membrane reached 12.1 kg m−2 h−1 during the separation of the pretreated SGPW at a feed flux of 40 L h−1 and a feed temperature of 40 °C. The rejection rate of the membrane to TDS in SGPW was over 99%. Fresh water with a conductivity of below 20 μs cm−1 was produced by VMD-C. The salts concentrated upstream of the membrane were recovered by a stirring crystallization process. The VMD-C system resulted in a 61% cost savings compared to conventional SGPW treatment.

Elevated River Inputs of the Total Alkalinity and Dissolved Inorganic Carbon in the Northern Adriatic Sea

The response of coastal systems to global acidification depends strongly on river inputs, which can alter the total alkalinity (AT) and dissolved inorganic carbon (DIC) in seawater. The northern Adriatic Sea (NAd) is a shallow continental shelf region that currently receives about 15% of the total freshwater input in the Mediterranean Sea, where the role of riverine discharges on the carbonate system has been poorly studied. In particular, river discharges can alter the carbonate system in the sea, affecting both the equilibrium chemistry and biological processes. For the main rivers flowing into the NAd (the Po, Adige, Brenta, Piave, Livenza, Tagliamento, Isonzo, Timavo and Rižana), data were collected for the pH, concentrations of the total alkalinity (AT), Ca2+ and Mg2+ and the isotopic ratio of stable carbon in the dissolved inorganic carbon (δ13CDIC). The DIC fluxes were estimated using the THINCARB (THermodynamic modeling of INOrganic CARBon) model for the compilation of the AT and pH data. The results show that the total transport of the AT in the rivers was 205 Gmol yr−1 while the transport of the DIC was 213 Gmol yr−1, of which about 70% was from the Po River. About 97% of the DIC in the river waters was in the form of bicarbonates. The high Mg2+/Ca2+ ratios indicate that dolomite weathering is predominant in the Adige, Piave, and Livenza river basins, while lower ratios in the Timavo and Rižana rivers indicate a greater proportion of calcite. The mean δ13C-DIC value was estimated to be −10.0 ± 1.7 ‰, a value nowadays considered typical for the DIC flux inputs in oceanic carbon cycle modeling. The DIC flux depends on the mineral weathering and biological activity in each river basin. However, these natural processes can be modified by anthropogenic disturbances that should be better quantified.

EVALUATION OF GROUND WATER QUALITY IN Al-BAIDH FIELD, HODIEDA CITY, YEMEN

Ground water is the main source for drinking water in Hodieda city, Yemen. This study discusses the chemical and physical characteristics of nineteen ground water wells in the Al-baidh field. Thus, the measurement of water quality parameters such as electrical conductivity EC, total dissolved solids TDS, pH, turbidity, color, total alkalinity, total hardness TH , NO3-,SO42-, PO43-, Cl- ,Na+, K+, Ca2+ and Mg2+ in addition to Mn, Cu, Fe and Cr were expressed. The results indicate unacceptable&#x0D; levels of TDS , Cl-, Na+ , Ca2+ and Mg2+comparing with the maximum tolerable concentration given by World Health Organization (WHO) and Yemen standard (YS). Elsewhere, the measurement of SO42- and NO3- exceeded the allowable values given by WHO and Y.S for most the samples which can be attributed to the nature of the geological and chemical structure of soil in Albaidh field. In this study, measurement of the concentration for elements such as Cr, Fe, and Mn were carried out, the results indicate that the values for this elements were within the allowable ranges. In this paper the concepts of star- refinement and strongly star- refinement of covering are extended to fuzzy topological space in the sense of Chang, basic theorem for covering dimension of normal fuzzy topological space is proved . Also, the small inductive dimension function is extended to fuzzy topological space, and some results for this inductive dimension in Chang’s space are obtained.

Coal-mining subsidence changed distribution of the microbiomes and their functional genes in a farmland.

Land subsidence is a serious geological event, and can trigger severe environmental and ecological issues. In this study, the influences of coal-mining subsidence on distribution of farmland microbiomes and their functional genes were investigated by 16 S ribosomal RNA (rRNA) gene and metagenome sequencing. The results showed the existence of a core microbiome, which determined the community compositions across the subsidence farmland. Subsidence decreased the relative abundances of dominant Streptomyces, Nocardioides, and Rhizophagus, but increased the relative abundances of dominant Bradyrhizobium, Rhizobium, and Trichoderma. Subsidence also decreased the relative abundances of genes related to carbon metabolism, Quorum sensing, aminoacyl-transfer RNA (tRNA) biosynthesis, and oxidative phosphorylation, and increased the relative abundances of genes related to two-component system and bacterial chemotaxis. Furthermore, subsidence weakened the biosynthesis of organic carbons by decreasing the relative abundances of genes encoding glycosyl transferases, and strengthened decomposition of degradable organic carbons of the microbiomes and auxiliary activities by increasing the relative abundances of genes encoding glycoside hydrolases and polysaccharide lyases. The concentrations of total phosphorus, Mg2+ , and Ca2+ at the lower areas were significantly higher than those at the upper areas, indicating an associated loss of soil nutrients. Canonical correspondence analysis showed that soil moisture, pH, and the concentrations of NH4 + and Ca2+ were the main factors affecting the distribution of the microbiomes and their functional genes. Collectively, this study shows that coal-mining subsidence alters soil physicochemical properties and distribution of farmland microbiomes and their functional genes.

Current opinion on the regulation of small intestinal magnesium absorption.

Magnesium (Mg2+) has an important role in numerous biological functions, and Mg2+ deficiency is associated with several diseases. Therefore, adequate intestinal absorption of Mg2+ is vital for health. The small intestine was previously thought to absorb digested Mg2+ exclusively through an unregulated paracellular mechanism, which is responsible for approximately 90% of total Mg2+ absorption. Recent studies, however, have revealed that the duodenum, jejunum, and ileum absorb Mg2+ through both transcellular and paracellular routes. Several regulatory factors of small intestinal Mg2+ uptake also have been explored, e.g., parathyroid hormone, fibroblast growth factor-23, apical acidity, proton pump inhibitor, and pH-sensing channel and receptors. The mechanistic factors underlying proton pump inhibitor suppression of small intestinal Mg2+, such as magnesiotropic protein dysfunction, higher mucosal bicarbonate secretion, Paneth cell dysfunction, and intestinal inflammation, are currently being explored. The potential role of small intestinal microbiomes in Mg2+ absorption has also been proposed. In this article, we reviewed the current knowledge on the mechanisms and regulatory factors of small intestinal Mg2+ absorption.

A Localized Assessment of Groundwater Quality Status Using GIS-Based Water Quality Index in Industrial Zone of Faisalabad, Pakistan

Groundwater risks driven by population growth and industrialization in metropolitan cities have become a worldwide problem. Faisalabad is Pakistan’s third largest city with a population of more than 2 million and is renowned for its diverse industries. Many factories in the area dump their untreated effluent into nearby drainage systems, having a direct negative effect on the marine ecosystem. This research focuses on the Madhuana drain and Khurrianwala industrial region of Faisalabad to investigate groundwater quality status. Sixty water samples from groundwater bore wells and open wells were obtained, and all these samples were subjected to lab experiments for physical and chemical analysis. Sixteen physiochemical parameters, namely, electrical conductivity (EC), pH, total dissolved solids (TDS), total suspended solids (TSS), turbidity, carbonate, Ca2+, Fe, HCO3−, Cl−, Mg2+, SO24−, As, Cr, Cu, and Mn, were examined. To provide a comprehensive picture of water quality from a human perspective, we calculated the water quality index (WQI) by integrating 16 physiochemical criteria. The results revealed that a larger proportion had poor drinking quality due to direct releases of toxins by industries. It was observed that 87% of the water samples showed an unsuitable status of groundwater for drinking purposes in terms of pH, EC, Fe, Mn, Cu, and Cr. The results of this study could be used to build and construct wastewater treatment plant facilities for the Madhuana drain, reducing pollution loads on the drain and river, as well as contaminant seepage rates into groundwater. The research’s resulting maps will help policymakers to manage groundwater supplies more efficiently for sustainable development.

Precise determination of dolomite content in marine sediments

AbstractDolomite (CaMg[CO3]2) is a common rock‐forming mineral. Nevertheless, its mechanisms of formation and the factors that cause dolomite concentration variations within the sedimentary records constitute long‐standing geochemical questions. In addition, the flux of Mg2+leaving the ocean by the formation of dolomite is a controversial question, with some studies arguing that dolomite formation is a negligible Mg2+sink in the modern ocean, while others show that it constitutes more than 50% of the total Mg2+removal rate. An important factor that impedes the resolution of the dolomite Mg2+flux is the lack of analytical methods with adequate precision and detection limit to directly measure minute quantities of authigenic dolomite in marine sediments. Here, we present a new analytical method for direct, precise measurement of dolomite content in marine sediments. The method is based on sequential leaching of carbonate minerals in acid and tracks the CO2emitted by the dissolution. Based on the measurement of gravimetric standards of calcite and dolomite, the method's detection limit and precision were determined as better than 0.2 and ± 0.2 dry wt% of dolomite, respectively. The method out‐performed dolomite quantification made by x‐ray diffraction and by inductive coupled plasma mass‐spectrometry, which provided precision of ± 2 and ± 1 dry wt%, respectively. Measurements of the dolomite content in modern sediments from the seafloor below the oligotrophic Eastern Mediterranean and the eutrophic Mississippi plume, and in clayey‐silty alluvial soil from south‐eastern Israel, demonstrated that the aforementioned precisions are also valid for natural samples.

Membrane distillation combined with electrocoagulation and electrooxidation for the treatment of landfill leachate concentrate

The landfill leachate concentrate is a kind of waste water containing salt and refractory organics produced by the membrane bioreactor-nanofiltration/reverse osmosis process. In the present work, three integrated processes of electrocoagulation (EC)-direct contact membrane distillation (DCMD), electrooxidation (EO)-DCMD and EC-EO-DCMD were used to treat the leachate concentrate. The results show that the total organic carbon (TOC), Ca2+ and Mg2+ removal rates of the EC process were 40.52%, 98.03% and 88.84%, respectively, under the optimal operating conditions. The TOC removal rate of the EO process was 64.62% under the optimal operating conditions. The removal rates of TOC, Ca2+ and Mg2+ by combined EC-EO process were 82.16%, 99.04% and 94.22%, respectively. When the MD was applied together with the EC and EO steps, the flux improved 23%∼42%, which was confirmed by the SEM-EDS, FTIR and XRD analysis that only quite a small amount of humic acid and fulvic acid substances was observed to be randomly deposited on the membrane surface. During 72 h operation, the permeate had a lower conductivity than 15 μS/cm, and only a small amount of organic (TOC < 9.6 mg/L) was detected. These results clearly demonstrated that the EC and EO processes can effectively reduce the refractory organics and scaling inorganics, and coupled with MD can synergistically to remove the pollutant that providing a better choice for the treatment of leachate concentrate.

An Analysis on the Characteristics and Influence Factors of Soil Salinity in the Wasteland of the Kashgar River Basin

Clarifying the salt ion composition characteristics and the influence factors of soil salinization of the wasteland in the Kashgar River Basin is of high importance for saline land improvement and utilization in this region. We studied the characteristics and influence factors of soil salinity in the wasteland of the Kashgar River Basin through classical statistics, principal component analysis and grey relational theory. The results showed that the total salt content had a T-shaped distribution pattern in the soil profile. As the most important ions, Cl−, Na+, and SO42− have the characteristics of vertical differentiation from top to bottom in the soil profile. Correlation analysis showed that the total salt content was negatively correlated to the HCO3− content and positively correlated to other salt ions, The most correlated anions were SO42− and Cl−. Na+, the most important cation, had the closest relationship with Cl−, followed successively by SO42− and HCO3−. Principal component analysis showed that SO42−, total salt content, Na+, Cl−, Mg2+, and Ca2+ could represent soil salinity status and salt ion composition, while HCO3− could represent soil alkalization status. The grey relational analysis indicated a differentiation in the intensity of influence of each factor on soil salinization at different depths. Except for groundwater burial depth and elevation, the relational degree between other influence factors and soil salt content decreased with depth. Our research findings offer important clues for understanding the soil salinity characteristics and influence factors of salinization in the wasteland of the Kashgar River Basin.

The first application of sensory structures based on photoelectric transducer for the study of enzymatic reactions

Background. The development of highly sensitive sensor equipment with the possibility of registering analytes in real time is a fast growing research area and a promising diagnostic biomedical technology. Currently, the standard laboratory method for determining the activities of ATPses is an indirect spectroscopic study of the concentration of inorganic phosphate formed as a result of ATP hydrolysis by these enzymes. However, there is no commercially available phosphate sensor with satisfactory parameters of sensitivity, selectivity and stability over time. The purpose of our research was the deve­lopment of a photoelectric recombination sensor system for the real-time detection of biochemical markers and its testing on the example of screening ATPase activity of rat erythrocyte plasma membrane suspension preparations. Materials and Methods. Experiments were performed on suspension preparations of plasma membranes of erythrocytes of Wistar rats. Preparations of plasma membrane suspensions obtained by Dodge method from each animal were divided into aliquots and used for the simultaneous study of ATPase activity by the reference method of Rathbun &amp; Betlach, as well as the registration of photocurrents induced during the passage of the ATPase reaction using the photoelectric recombination multisensor system of our own design. Results. The application of silicon sensory structures based on photoelectrical transducer principle for detecting the activity of adenosine triphosphate hydrolases on the example of total Mg2+,Na+,K+-ATPases preparations of plasma membranes of rat erythro­cytes has been experimentally tested. The directly measured analytic parameter is the photocurrent of the deep silicon barrier structure under illumination with high absorption coefficient. The physical features of the device operation have been examined. Detection of such metabolites becomes possible due to reactions intermediates with their own dipole moment (inorganic phosphate, which is one of the products of ATP hydrolysis). The drastic change of photocurrent that characterizes the course of biochemical reaction was observed in real time. The effect is explained by local electrostatic influence on the parameters of recombination centers at the silicon surface that results in surface recombination velocity change. The sensor operation is qualitatively explained in the frame of Stevenson-Keyes’s theory. Conclusions. Our approach can be regarded as a promising way to elaborate technically simple and highly sensitive method for detection of quantitative behavior of enzymatic reactions. Moreover, the local modification of silicon surface allows obtaining time depending scenarios of the adsorption and thus improving the sensitivity of the sensor. These circumstances open up the possibility of elaborating the complex sensory structures with optimized parameters for certain enzymatic reactions.

Magnesium Limitation Leads to Transcriptional Down-Tuning of Auxin Synthesis, Transport, and Signaling in the Tomato Root.

Magnesium (Mg) deficiency is becoming a widespread limiting factor for crop production. How crops adapt to Mg limitation remains largely unclear at the molecular level. Using hydroponic-cultured tomato seedlings, we found that total Mg2+ content significantly decreased by ∼80% under Mg limitation while K+ and Ca2+ concentrations increased. Phylogenetic analysis suggested that Mg transporters (MRS2/MGTs) constitute a previously uncharacterized 3-clade tree in planta with two rounds of asymmetric duplications, providing evolutionary evidence for further molecular investigation. In adaptation to internal Mg deficiency, the expression of six representative MGTs (two in the shoot and four in the root) was up-regulated in Mg-deficient plants. Contradictory to the transcriptional elevation of most of MGTs, Mg limitation resulted in the ∼50% smaller root system. Auxin concentrations particularly decreased by ∼23% in the Mg-deficient root, despite the enhanced accumulation of gibberellin, cytokinin, and ABA. In accordance with such auxin reduction was overall transcriptional down-regulation of thirteen genes controlling auxin biosynthesis (TAR/YUCs), transport (LAXs, PINs), and signaling (IAAs, ARFs). Together, systemic down-tuning of gene expression in the auxin signaling pathway under Mg limitation preconditions a smaller tomato root system, expectedly stimulating MGT transcription for Mg uptake or translocation.

Mechanisms of releasing magnesium ions from a magnesium anode in an electrolysis reactor with struvite precipitation

The electrochemical precipitation of struvite (MgNH4PO4) using the sacrificed magnesium anode is a new and effective method to recover phosphorus from wastewater. However, insufficient knowledge about the mechanism of Mg2+ released from the magnesium anode and the variation of the outer anode layer related to the hydrogen evolution and electrolysis reactions limits the development and application of electrochemical precipitation methods. To better understand the role of magnesium anode in electrochemical reactions, an electrolysis reactor with a magnesium anode was used to recover phosphate from synthetic wastewater containing 10 and 100 mg/L-P, respectively. The results showed that the composition of the produced precipitates mainly depended on the phosphorus concentration in the synthetic wastewater, because the predominant precipitates changed from Mg(OH)2 to MgNH4PO4 as the concentration increased. Besides, the proportion of Mg2+ from the hydrogen evolution reaction in total Mg2+ production decreased with increased applied current. Meanwhile, the current application facilitated struvite precipitation and weakened the adsorption of struvite on the Mg anode surface. The results revealed that when the Mg anode was polarized in ammonia and phosphorus solution, an outer mixed film consisting of Mg(OH)2/MgNH4PO4/MgCO3 on top of a MgO-rich inner layer formed on the Mg anode surface. These findings are contributing to the comprehensive understanding and improvement of using magnesium anode for recovering phosphorus from wastewater.

Comparative effects of ascobin and glutathione on copper homeostasis and oxidative stress metabolism in mitigation of copper toxicity in rice.

Copper (Cu) pollution of agricultural land is a major threat to crop production. Exogenous chemical treatment is an easily accessible and rapid approach to remediate metal toxicity, including Cu toxicity in plants. We compared the effects of ascobin (ASC; ascorbic acid:citric acid at 2:1) and glutathione (GSH) in mitigation of Cu toxicity in rice. Plants subjected to Cu stress displayed growth inhibition and biomass reduction, which were connected to reduced levels of chlorophylls, RWC, total phenolic compounds, carotenoids and Mg2+ . Increased accumulation of ROS and malondialdehyde indicated oxidative stress in Cu-stressed plants. However, application of ASC or GSH minimized the inhibitory effects of Cu stress on rice plants by restricting Cu2+ uptake and improving mineral balance, chlorophyll content and RWC. Both ASC and GSH pretreatments reduced levels of ROS and malondialdehyde and improved activities of antioxidant enzymes, suggesting their roles in alleviating oxidative damage. A comparison on the effects of ASC and GSH under Cu stress revealed that ASC was more effective in restricting Cu2+ accumulation (69.5% by ASC and 57.1% by GSH), Ca2+ and Mg2+ homeostasis, protection of photosynthetic pigments and activation of antioxidant defence mechanisms [catalase (110.4%), ascorbate peroxidase (76.5%) and guaiacol peroxidase (39.0%) by ASC, and catalase (58.9%) and ascorbate peroxidase (59.9%) by GSH] in rice than GSH, eventually resulting in better protection of ASC-pretreated plants against Cu stress. In conclusion, although ASC and GSH differed in induction of stress protective mechanisms, both were effective in improving rice performance in response to Cu phytotoxicity.

An evaluation of the core bacterial communities associated with hypersaline environments in the Qaidam Basin, China

Hypersaline lakes and saltern areas are important industrial and biodiversity resources in the Qaidam Basin of China that reside at > 2600m asl. Most hypersaline environments in this area are characterized by saturated salinity (~ 300g/L salinity), nearly neutral pH, intense ultraviolet radiation, and extremely variable temperature fluctuations. The core bacterial communities associated with these stressful environments have nevertheless remained uninvestigated. 16S rRNA gene Illumina sequencing analyses revealed that the bacterial communities were dominated by core lineages including the Proteobacteria (39.4-64.6%) and the Firmicutes (17.0-42.7%). However, the relative abundances of common lineages, and especially the five most abundant taxa of Pseudomonas, Lactococcus, Anoxybacillus, Acinetobacter, and Brevundimonas, were highly variable across communities and closely associated with hypersaline characteristics in the samples. Network analysis revealed the presence of co-occurrence high relative abundance taxa (cluster I) that were highly correlated across all hypersaline samples. Additionally, temperature, total organic carbon, K+, and Mg2+ correlated highest with taxonomic distributions across communities. These results highlight the potential mechanisms that could underlie survival and adaptation to these extreme hypersaline ecosystems.

Canonical Correspondence Analysis Ordinations and Competitor, Stress Tolerator, and Ruderal Strategies of Coastal Dune Plants in South Korea

Lee, J.-S.; Son, D.-H.; Lee, S.-H.; Myeong, H.-H.; Cho, J.-S.; Lee, J.-C.; Lee, J.-Y.; Park, C.-S., and Kim, J.-W., 2020. Canonical correspondence analysis ordinations and competitor, stress tolerator, and ruderal strategies of coastal dune plants in South Korea. Journal of Coastal Research, 36(3), 528–535. Coconut Creek (Florida), ISSN 0749-0208.The distribution of plant communities in the sand dunes of the SW coasts of South Korea was studied, along with environmental factors and plant traits, by canonical correspondence analysis (CCA). The competitor, stress tolerator, and ruderal (CSR) ecological strategies were also evaluated. The coastal sand dune plants were classified into two plant trait groups in the CCA biplot diagram. First, vegetation was correlated with leaf dry weight, canopy height, specific leaf area, leaf dry matter content, and lateral spread. Second, it was correlated with the flowering period and flowering start. Coastal sand dune plants were classified into three soil factor groups in axes 1 and 2 of the CCA biplot diagram. First, the vegetation was correlated with total nitrogen (T-N), K+, Silt, Mg2+, Na+, and clay contents. Second, it was correlated with Ca2+. Third, it was correlated with the sand contents. To elucidate the relative significance of competition, stress, and disturbance in the distribution process of plant communities, the CSR distribution model was adopted. Many coastal plants (12 species) showed competitor-ruderal/competitor-stress-tolerant-ruderal strategies: Artemisia fukudo, Atriplex gmelinii, Carex kobomugi, Calystegia soldanella, Digitaria ciliaris, Linaria japonica, Messerschmidia sibirica, Oenothera bieenis, Salicornia europaea, Salsola komarovii, Suaeda glauca, and Suaeda maritima. The four species with stress-tolerant-competitor/competitor-stress-tolerant-ruderal strategies were Carex pumila, Imperata cylindrica var. koenigii, Limonium tetragonum, and Zoysia sinica. Conyza canadensis, Ischaemum anthephoroides, Phragmites communis, and Vitex rotundifolia displayed competitor/stress-tolerant-competitor, competitor-ruderal, stress-tolerant-competitor, and C/SC strategies, respectively. The differences in distribution and restoration patterns of the CCA diagrams and CSR triangles may be attributable to different adaptions of plant traits or soil factors.