Low NA Research Articles

A soybean sodium/hydrogen exchanger GmNHX6 confers plant alkaline salt tolerance by regulating Na+/K+ homeostasis.

Alkaline soil has a high pH due to carbonate salts and usually causes more detrimental effects on crop growth than saline soil. Sodium hydrogen exchangers (NHXs) are pivotal regulators of cellular Na+/K+ and pH homeostasis, which is essential for salt tolerance; however, their role in alkaline salt tolerance is largely unknown. Therefore, in this study, we investigated the function of a soybean NHX gene, GmNHX6, in plant response to alkaline salt stress. GmNHX6 encodes a Golgi-localized sodium/hydrogen exchanger, and its transcript abundance is more upregulated in alkaline salt tolerant soybean variety in response to NaHCO3 stress. Ectopic expression of GmNHX6 in Arabidopsis enhanced alkaline salt tolerance by maintaining high K+ content and low Na+/K+ ratio. Overexpression of GmNHX6 also improved soybean tolerance to alkaline salt stress. A single nucleotide polymorphism in the promoter region of NHX6 is associated with the alkaline salt tolerance in soybean germplasm. A superior promoter of GmNHX6 was isolated from an alkaline salt tolerant soybean variety, which showed stronger activity than the promoter from an alkaline salt sensitive soybean variety in response to alkali stress, by luciferase transient expression assays. Our results suggested soybean NHX6 gene plays an important role in plant tolerance to alkaline salt stress.

Morphogenetic Response of Assorted Rice Genotypes to Salinity in Tanzania

Salinity, where salts concentrate on the soil surface causing severe decline of crop yields, is a worldwide problem. In Tanzania salinity is one of the major soil degradation challenges affecting over 3.5 million hectares limiting agriculture productivity of various crops including rice. Most of the varieties grown are sensitive to salts and inadequate tolerant cultivars available in the country. A hydroponics mass screening technique using Yoshinda Solution was used to test the 102 genotypes in NaCl- saline treated and non-treated solution at Tanzania Agricultural Research Institute (TARI-Dakawa Centre). Different salt concentrations (4 dSm-1, 6 dSm-1, 8 dSm-1 and 10 dSm) were used and the experiment was done in three replications. The genotypic variability for salinity tolerance was observed as less salt injury symptoms, low Na+ accumulation and Na+/K+ ratio in plant tissues and high biomass accumulation (fresh weight and dry weight). Results revealed further those 28 genotypes (28.45%) out of 102 showed tolerance to salinity, at high salinity level of 10dSm-1. Lines namely SR35266-2-18-2-1, SR35250-1-19-1-1, SR23364-128-1762-1-HV-1-1, SR35230-1-12-1-1, SR23364-128-1986-1-HV-1-1, SR34590-HB3433-4-1-1, SR35266-2-7-1-1, PBR1000922-1 and SR34053 (#5-52)-1-4-2-10-3-3 showed high performance under high salt conditions. Others includes SR35266-3-1-5-1, SR34574-2-10-3-1-2-1, SR35278-2-10-1-1, SR35250-2-3-1-1, SR35266-3-2-3-1, SR35266-3-2-4-1, SR23364-133-184-1-HV-1-1, SR34592-HB-1-HV-1, and SR34042F3-22-1-1-5-3 indicated tolerance to salt and had high dry matter as well. All the genotypes had increased levels of Na+ and differential performance was observed in some genotypes under saline and non-saline conditions. Among these three lines namely SR35266-2-7-1-1, SR23364-128-1762-1-HV-1-1, and SR34590- HB3433-4-1-1expressed high dilution ability as the K+ and Na+ concentrations were lower compared to other genotypes. The study, therefore, suggests that the lines can be used in breeding programs to develop varieties with potential to salt tolerance and other traits.

Abstract 027: Early Life Sodium Restriction Programs Long-term Changes In Energy Flux And Autonomic Activity

As sodium (Na) retention by the kidney is not fully efficient until the final weeks of a normal gestation, prematurely born infants are at high risk of Na depletion. We hypothesize that early-life sodium depletion contributes to delayed somatic growth and increased cardiometabolic risks associated with premature birth, via programmed increases in autonomic activity. To model early-life Na depletion, mice were weaned at 3 weeks of age onto custom variations of a soy-free diet (Teklad 2920x) containing either low (0.04% n=6m+8f) or high (0.30% n=8m+8f) Na. At 6 weeks of age, all mice were returned to standard (0.15% Na) diet. Energy flux was studied using NMR and a multiplexed phenotyping system (Promethion) at 6, 7, 8, 10, and 18 weeks of age, and data were analyzed by General Linear Modeling to account for covariates such as fat-free mass (FFM) and fat mass. Low Na supply caused delayed gains in FFM (diet x age interaction p<0.01) but no change in fat mass (p>0.77) in both sexes. In male mice supplied low Na in early life, food intake was reduced for weeks to months after return to normal diet even after correction for FFM and fat masses (diet p<0.01, diet x age p=0.93), primarily due to smaller meal sizes. Water intake was increased (diet p<0.01, diet x age p=0.03), primarily due to more drinking events. Total daily energy expenditure was also increased even after correction for FFM mass, fat mass, and food intake (diet p<0.01, diet x age p>0.99), though no changes in locomotion were observed (p>0.60). Throughout, female mice exhibited qualitatively similar yet quantitatively smaller effects. A parallel study indicated that after low Na supply, basal metabolic rate was increased at 8 weeks of age (n=8m each, +16%, p=0.01), and this increase was abolished with autonomic blockade via hexamethonium (30 mg/kg, ip; p=0.02). Finally, preliminary data (n=4 vs 5) indicate Ucp1 mRNA may be increased in inguinal fat at 6 (2.8-fold p=0.08) and 18 weeks of age (2.2-fold p=0.12) in the low Na group. Together these findings support the concept that Na depletion in early life is sufficient to program persistent cardiometabolic and autonomic dysfunctions long after Na repletion.

Red@Black phosphorus core–shell heterostructure with superior air stability for high-rate and durable sodium-ion battery

Heterostructured electrodes have gained increasing attentions owing to the synergistic effects from individual building components and the unique interfaces. However, rational design and controllable fabrication of high areal capacity and durable phosphorus-based heterostructure anode for industry remains a critical challenge. Herein, a new red@black phosphorus core–shell heterostructure anchored on three-dimensional N-doped graphene (RP@BP/3DNG) has been prepared via a facile one-step solvothermal strategy. As demonstrated by experimental data and theoretical calculations, RP@BP/3DNG shows a superior high electronic conductivity and an extremely low Na+ diffusion barrier due to the build-in filed at the RP@BP heterointerface, thus RP@BP/3DNG delivers an ultra-high areal capacity of 3.46 mAh cm−2 (1440.2 mAh/g at 0.05 A/g), impressive rate performance (521.3 mAh/g at 10.0 A/g) as well as unprecedented capacity retention rate of 89.3% after 1200 cycles at 10.0 A/g when evaluated as an anode for sodium ion batteries (SIBs). Furthermore, the internal electric field at the interfaces of RP@BP leads to the shift of electron cloud from BP to RP, which greatly suppresses the reaction activity of lone-pair electrons of BP atoms, and therefore RP@BP/3DNG shows much enhanced air stability. This work heralds a new insight for designing high-performance and stable P-based anodes for rechargeable batteries.

Effect of valence state of cobalt in cobalt hexacyanoferrate coprecipitated at different temperatures on electrochemical behavior

Cobalt hexacyanoferrate (CoFe(CN)6; CoHCF) is coprecipitated as a cathode material in an Na-ion aqueous battery with varying solution temperatures of 5°C, 25°C, 50°C, and 70°C to tailor the particle size and defect content. At a low temperature, the small cubic particle is prepared with high Fe vacancies and low Na amounts. Conversely, an elevated temperature results in the enlarged particle with lower Fe vacancies and high Na amounts. Meanwhile, the lattice parameter is extended at a high temperature based on the Co2+ evolution with a larger ionic radius than that of the Co3+ ion at the Co site. Contrary with the expectations, a lower specific capacity is obtained for the highly crystalline structure at high temperature due to the evolution of the irreversible redox-inactive Co2+. The low temperature of 5°C confers an excellent rate capability, capacity retention of 89% at 20 times faster charging rate, based on the smaller particles and relieved distortion in cycling. The shorter diffusion path for Na intercalation due to the fine powder enables a faster charging process. Higher Fe vacancies induced at lower temperature limit Na accommodation, yielding a reduced distortion. The coprecipitation at low temperature enhances the rate performance and cyclability, sacrificing the capacity. Novelty Statement High temperature builds the large particle with low Fe vacancies and high Na amounts. High temperature derives the extended lattice constant due to Co2+ evolution in CoHCF. Evolution of the irreversible redox-inactive Co2+ degrades the specific capacity. Low temperature enhances rate performance due to small powder and relaxed distortion. High rate performance and cyclability at low temperature sacrifices the capacity.

Fracture of silicate glasses: Microcavities and correlations between atomic-level properties

We use large-scale simulations to investigate the dynamic fracture of silica and sodium-silicate glasses under uniaxial tension. The stress-strain curves demonstrate that silica glass is brittle whereas the glasses rich in Na show pronounced ductility. A strong composition dependence is also seen in the crack velocity which, for the strain rate considered, is on the order of 1800 m/s for glasses with low Na concentration and decreases to 650 m/s if the concentration is high. We find that during the fracture of Na-rich glasses very irregular cavities as large as 3--4 nm form ahead of the crack front, indicating the presence of nanoductility in these glasses. Before fracture occurs, the local composition, structure, and mechanical properties are heterogeneous in space and show a strong dependence on the applied strain. Further analysis of the correlations between these local properties allows to obtain a better microscopic understanding of the deformation and fracture of oxide glasses and how the local heating close to the crack tip, up to several hundred degrees, permits the structure to relax.

Nickel toxicity pretreatment attenuates salt stress by activating antioxidative system and ion homeostasis in tomato (Solanum lycopersicon L.): an interplay from mild to severe stress.

Plants antioxidative system is the first line of defense against oxidative stress caused secondarily by toxic ions under salinity. Plants with pre-activated antioxidative system can better adapt to salinity and can result in higher growth and yield. The current experiment was conducted to assess the adaptation of two tomato genotypes (Riogrande and Green Gold) with pre-activated antioxidative enzymes against salt stress. Tomato seedlings were exposed to mild stress (Ni: 0, 15 and 30mgL-1) for three weeks to activate the antioxidative enzymes. The seedlings with pre-activated antioxidative enzymes were then grown under severe stress in hydroponics (0, 75 and 150mMNaCl) and soil (control, 7.5 and 15 dSm-1) to check the adaptation, growth and yield. The results showed that Ni toxicity significantly enhanced activities of antioxidant enzymes (SOD, CAT, APX and POX) in both the genotypes and reduced growth with higher values in genotype Riogrande than Green Gold. The seedlings with pre-activated antioxidant enzymes showed better growth, low Na+ and high K+ uptake and maintained higher antioxidative enzymes activity than non-treated seedlings after four weeks of salt stress treatment in hydroponics. Similarly, the results in soil salinity treatment of the Ni pretreated seedlings showed higher yield characteristics (fruit yield per plant, average fruit weight and fruit diameter) than non-treated seedlings. However, Ni pretreatment had nonsignificant effect on tomato fruit quality characteristics like fruit dry matter percentage, total soluble solids, fruit juice pH and titratable acidity. The genotype Riogrande showed better growth, yield and fruit quality than Green Gold due to higher activity of antioxidant enzymes and better ion homeostasis as a result of Ni pretreatment. The results suggest that pre-activation antioxidant enzymes by Ni treatment proved to be an effective strategy to attenuate salt stress for better growth and yield of tomato plants.

Three-dimensional porous N-doped graphite carbon with embedded CoS2 nanoparticles as advanced anode for sodium-ion batteries

To achieve both high capacity and long cycling stability in sodium-ion batteries (SIBs), the structural optimizations of anode materials should take into considerations of the reaction kinetics, the insertion/extraction processes of Na+, and the structural stability of anodes. In this study, the growth of CoS2 nanoparticles on N-doped graphite carbon three-dimensional nano-skeleton (CoS2/NGC) is designed to increase the active sites for sodium storage, to provide high ionic/electrical conductivity, and to alleviate the volume swelling and reduce Na+ diffusion energy barrier. As employed as anode materials of SIB, CoS2/NGC shows a great rate capability, affording an initial capacity of 660 mAh g−1, and maintaining a coulombic efficiency of 99.7% even after 1000 cycles at 1.0 A g−1. The cyclic voltammetry experiments demonstrate that the main contribution of the capacity is from the capacitive charge-storage. Density functional theory calculations reveal that the advantageous Na+ storage kinetics of the CoS2/NGC electrode is attributed to its low Na+ adsorption energy of −2.21 eV and low Na+ diffusion barrier of 0.113 eV. This systematic study paves a way for the efficient design of metal sulfides anodes for SIB, which is conducive to develop battery systems with remarkable electrochemical performance.

Low dietary sodium potentially mediates COVID-19 prevention associated with whole-food plant-based diets.

Compared with an omnivorous Western diet, plant-based diets containing mostly fruits, vegetables, grains, legumes, nuts and seeds, with restricted amounts of foods of animal origin, are associated with reduced risk and severity of COVID-19. Additionally, inflammatory immune responses and severe acute respiratory symptoms of COVID-19, including pulmonary oedema, shortness of breath, fever and nasopharyngeal infections, are associated with Na toxicity from excessive dietary Na. High dietary Na is also associated with increased risks of diseases and conditions that are co-morbid with COVID-19, including chronic kidney disease, hypertension, stroke, diabetes and obesity. This article presents evidence that low dietary Na potentially mediates the association of plant-based diets with COVID-19 prevention. Processed meats and poultry injected with sodium chloride contribute considerable amounts of dietary Na in the Western diet, and the avoidance or reduction of these and other processed foods in whole-food plant-based (WFPB) diets could help lower overall dietary Na intake. Moreover, high amounts of K in plant-based diets increase urinary Na excretion, and preagricultural diets high in plant-based foods were estimated to contain much lower ratios of dietary Na to K compared with modern diets. Further research should investigate low Na in WFPB diets for protection against COVID-19 and co-morbid conditions.

Dietary Patterns of 479 Indonesian Adults and Their Associations with Sodium and Potassium Intakes Estimated by Two 24-h Urine Collections.

The excess sodium (Na) intake and insufficient potassium (K) intake are frequently observed all over the world, including Indonesia. This study explored the dietary patterns of Indonesian people and evaluated their associations with Na and K intakes. Na and K intakes were assessed by repeated 24-h urine collection. The dietary patterns of the previous month were extracted by factor analysis using the Indonesian Food Frequency Questionnaire. The participants were community-dwelling Indonesian men and women (n = 479) aged 20 years and over. We identified four dietary patterns in each sex. After controlling for confounding factors, the high quantile of ‘Noodle, oil, and salty sea products’ pattern was associated with the high Na intake in both men and women (p = 0.02 and <0.001, respectively). The ‘Meat, vegetable, oil, and fruit’ pattern statistically significantly contributed to the high K intake in men (p = 0.04), but not in women (p = 0.26). The ‘Vegetable, non-oil, and milk’ pattern in men and ‘Meat, vegetable, and fruit’ pattern in women were associated with low Na:K ratios (p = 0.03 and 0.01, respectively). Neither ‘bread’ nor ‘fish’ appeared as a major determinant of any dietary patterns in this population. The ‘Noodle, oil, and salty sea products’ pattern should be avoided to reduce sodium intake.

Screening of finger millet genotypes for sodicity tolerance using the Na+/K+ ratio as a major physiological trait

Sodicity affects a larger area than salinity, but research on the sodicity tolerance mechanism is limited. The study was carried out to screen 120 finger millet genotypes under sodic soil conditions and identify sodicity-tolerant genotypes. The experimental field soil conditions were sandy clay loam with pH 8.9, electrical conductivity (EC) 0.94 dSm-1 and exchangeable sodium percentage (ESP) 21.5, which was naturally sodic. Grain yield per plant and Na+/K+ ratio were recorded for each genotype to screen sodicity tolerance among the genotypes. A significantly higher grain yield per plant than that of the sodicity-tolerant check variety TRY 1 (23.10 g) was observed in 30 finger millet genotypes. The analysis of sodium and potassium revealed that these 30 finger millet genotypes also recorded a significantly lower Na+/K+ ratio, which is comparatively lower than that of the sodicity-tolerant check variety TRY 1 (0.23 Na+/K+ ratio). The genotypes (FIN 3045, FIN 2875, FIN 3077, FIN 3015, FIN 3063, FIN 2861, FIN 3028, FIN 2867, FIN 2854, FIN 2860, FIN 2872, FIN 2896, FIN 4268, FIN 3034, FIN 3928, FIN 3104, FIN 3965, FIN 3091, FIN 2960, FIN 3994, FIN 4198, FIN 3174, FIN 3078, FIN 4288, FIN 4202, FIN 4238, FIN 3089, FIN 4205, FIN 3966 and FIN 3182) that recorded higher grain yield per plant and lower Na+/K+ ratio can be considered sodicity tolerant. These genotypes with a high grain yield per plant and a low Na+/K+ ratio could be utilized in stress breeding programs to develop sodicity-tolerant finger millet varieties.

Magnetopriming Actuates Nitric Oxide Synthesis to Regulate Phytohormones for Improving Germination of Soybean Seeds under Salt Stress.

In this study, the role of the signalling molecule nitric oxide (NO) in magnetopriming-mediated induction of salinity tolerance in soybean seeds is established. The cross-talk of NO with germination-related hormones gibberellic acid (GA), abscisic acid (ABA) and auxin (IAA) for their ability to reduce the Na+/K+ ratio in the seeds germinating under salinity is highlighted. Salt tolerance index was significantly high for seedlings emerging from magnetoprimed seeds and sodium nitroprusside (SNP, NO-donor) treatment. The NO and superoxide (O2•−) levels were also increased in both of these treatments under non-saline and saline conditions. NO generation through nitrate reductase (NR) and nitric oxide synthase-like (NOS-like) pathways indicated the major contribution of NO from the NR-catalysed reaction. The relative expression of genes involved in the NO biosynthetic pathways reiterated the indulgence of NR in NO in magnetoprimed seeds, as a 3.86-fold increase in expression was observed over unprimed seeds under salinity. A 23.26-fold increase in relative expression of NR genes by the NO donor (SNP) was observed under salinity, while the NR inhibitor (sodium tungstate, ST) caused maximum reduction in expression of NR genes as compared to other inhibitors [L-NAME (N(G)-nitro-L-arginine methyl ester; inhibitor of nitric oxide synthase-like enzyme) and DPI (diphenylene iodonium; NADPH oxidase inhibitor)]. The ratio of ABA/GA and IAA/GA decreased in magnetoprimed and NO donor-treated seeds, suggesting homeostasis amongst hormones during germination under salinity. The magnetoprimed seeds showed low Na+/K+ ratio in all treatments irrespective of NO inhibitors. Altogether, our results indicate that a balance of ABA, GA and IAA is maintained by the signalling molecule NO in magnetoprimed seeds which lowers the Na+/K+ ratio to offset the adverse effects of salinity in soybean seeds.

Hydrochemical and quality assessment of irrigation water at the trans-himalayan high-altitude regions of Leh, Ladakh, India

A total of seventy irrigation water samples were collected from Leh, Ladakh, India, to determine their hydrochemistry profile and water quality for irrigation purposes. Water quality indices such as total hardness (TH), residual sodium carbonate (RSC), potential salinity (PS), permeability index (PI), Kelly's ratio (KR), sodium absorption ratio (SAR), corrosivity ratio (CR), and chloroalkaline indices (CAI) were measured. The Piper diagram, Durov's diagram, and United States Salinity Laboratory (USSL) diagram were drawn to determine the water types, ion exchange processes, and rock–soil–water interaction. The findings indicated that the hydrochemical characteristics of irrigation water are naturally alkaline. Furthermore, water quality parameters revealed that the study area’s surface water is suitable for irrigation purposes, despite relatively high TH and MH levels. The level of CR indicated that water should not be transported using metal pipes. The CAI and Durov's plot indicated direct ionic exchange processes controlling water chemistry. Additionally, this irrigation water is mainly dominated by the Ca2+–Cl−–SO42−, Na+–K+–CaCO3 + HCO3−, and Na+–K+–Cl− type, which indicates silicate rock weathering along with some anthropogenic input. The USSL salinity diagram indicated a medium salinity and low Na hazard. Hence, it is concluded that the rock weathering cycle is the natural source of all the cations and anions, and these ions pass directly from water to rock and vis-à-vis, along with some input of anthropogenic activity.

Crystal-Chemical Observations and the Relation Between Sodium and H2O in Different Beryl Varieties

ABSTRACTBeryl (Be3Al2Si6O18) is a well-known mineral, most famously in its vivid green form of emerald, but also as a range of other colors. Prominent varieties of beryl aside from emerald include aquamarine, red beryl, heliodor, goshenite, and morganite. There has not been a significant amount of research dedicated to comparing the crystal-chemical differences among the varieties of beryl except in determining chromophoric cations. While the H2O content within structural channels of emerald has been explored, and the H2O content of individual beryl specimens has been studied, there has not yet been a study comparing the H2O content systematically across beryl varieties. In this study we consider single-crystal X-ray diffraction data and electron probe microanalyses of 80 beryl specimens of six primary varieties, to compare and contrast their crystal chemistry. Beryl cation substitutions are dominantly coupled substitutions that require Na to enter a structural channel site. The results indicate that with increasing Na content beryl varieties diverge into two groups, characterized by substitutions at octahedral or tetrahedral sites, and that the dominant overall cation substitutions in each beryl variety tend to be different in more than just their chromophores. We find that the relation between Na and H2O content in beryl is consistent for beryl with significant Na content, but not among beryl with low Na content. Natural red beryl is found to be anhydrous, and heliodor has Na content too low to reliably determine H2O content from measured Na. We determined equations and recommendations to relate the Na and H2O content in emerald, aquamarine, goshenite, and morganite from a crystallographic perspective that is applicable to beryl chemistry measured by other means. This research will help guide future beryl studies in classifying beryl variety by chemistry and structure and allow the calculation of H2O content in a range of beryl varieties from easily measured Na content instead of requiring the use of expensive or destructive methods.

Analysis of sequence polymorphism of OsHKT1;5 gene in rice (Oryza sativa L.)

In salt stress conditions, the excessive accumulation of Na+ ion in the cytoplasm could cause ion toxicity, metabolic imbalances, and reduction in growth of plant. The ability of maintaining a low Na+ concentrations or low Na+/K+ ratio in cytosol plays the important roles of plant adapt to salinity stress. In rice, the HKT transporter family has been proven to be critical for salt tolerance and the maintenance of Na+, K+ homeostasis under salinity conditions. In this study, we conducted the sequence polymorphisms analysis in the OsHKT1;5 coding region in order to detect the potential allelic variants in some local rice cultivars in Viet Nam. The exon 1 region and exon 2-3 region of OsHKT1;5 gene were amplified by PCR in two separate reactions. After direct sequencing of PCR products, the full length coding region of OsHKT1;5 gene was obtained and compared to reference Nipponbare OsHKT1;5 coding sequence. Accordingly, twelve nucleotide substitutions in coding sequence of OsHKT1;5 were identified, including six non-synonymous substitutions (G382A, C418G, G551A, C994G, C1183G, A1630C) and the other six synonymous substitutions (G225A, C1038G, G1152A, G1261A, G1304C, C1608T). Further analysis revealed that six non-synonymous substitutions (G382A, C418G, G551A, C994G, C1183G, A1630C) caused the changes in amino acids (D128N, P140A, R184H, H332D, V395L, and S544R). The single nucleotide polymorphism A1630C leading substitution of S544R was newly found in the Chiem Rong cultivar. In silico analysis of protein structure and post-translational modifications indicated that amino acid substitutions had no influence on protein structure but led to changes in post-translational modifications such as phosphorylation and SUMOylation.

Advanced anion-selective membranes with pendant quaternary ammonium for neutral aqueous supporting redox flow battery

Neutral aqueous organic redox flow battery (NAORFB) stands out as one of the most prospective mass energy storage options. The main limitations of large-scale storage regarding the NAORFB lie in the low Na+/Cl− conductivity of membrane in pH7 systems, which leads to a lower voltage efficiency. Herein, quaternary ammonium functionalized fluorinated poly (arylene ether) (QAFPAE-x) anion exchange membrane with hydrophilic and hydrophobic blocks was designed successfully. The results demonstrated that the grafting of quaternary ammonium and fluorine-containing block enables QAFPAE-x membrane low swelling, high Cl− conductivity, and promising chemical stability characteristics. The voltage efficiency of QAFPAE-100 membrane (93.8%–60.7%) is much higher than the AMVN membrane (88.4%–37.8%) at 20–160 mA cm−2. Furthermore, the NAORFB with the QAFPAE-100 membrane steadily runs at 60 mA cm−2 over 1500 cycles. Therefore, the ionic highway induced excellent performance of QAFPAE-100 membrane to render this material a promising candidate for practical NAORFB applications.

Kidney-Specific CAP1/Prss8-Deficient Mice Maintain ENaC-Mediated Sodium Balance through an Aldosterone Independent Pathway.

The serine protease prostasin (CAP1/Prss8, channel-activating protease-1) is a confirmed in vitro and in vivo activator of the epithelial sodium channel ENaC. To test whether proteolytic activity or CAP1/Prss8 abundance itself are required for ENaC activation in the kidney, we studied animals either hetero- or homozygous mutant at serine 238 (S238A; Prss8cat/+ and Prss8cat/cat), and renal tubule-specific CAP1/Prss8 knockout (Prss8PaxLC1) mice. When exposed to varying Na+-containing diets, no changes in Na+ and K+ handling and only minor changes in the expression of Na+ and K+ transporting protein were found in both models. Similarly, the α- or γENaC subunit cleavage pattern did not differ from control mice. On standard and low Na+ diet, Prss8cat/+ and Prss8cat/cat mice exhibited standard plasma aldosterone levels and unchanged amiloride-sensitive rectal potential difference indicating adapted ENaC activity. Upon Na+ deprivation, mice lacking the renal CAP1/Prss8 expression (Prss8PaxLC1) exhibit significantly decreased plasma aldosterone and lower K+ levels but compensate by showing significantly higher plasma renin activity. Our data clearly demonstrated that the catalytic activity of CAP1/Prss8 is dispensable for proteolytic ENaC activation. CAP1/Prss8-deficiency uncoupled ENaC activation from its aldosterone dependence, but Na+ homeostasis is maintained through alternative pathways.

Inverse Salt Sensitivity of Blood Pressure: Mechanisms and Potential Relevance for Prevention of Cardiovascular Disease.

To review the etiology of inverse salt sensitivity of blood pressure (BP). Both high and low sodium (Na+) intake can be associated with increased BP and cardiovascular morbidity and mortality. However, little is known regarding the mechanisms involved in the increase in BP in response to low Na+ intake, a condition termed inverse salt sensitivity of BP, which affects approximately 15% of the adult population. The renal proximal tubule is important in regulating up to 70% of renal Na+ transport. The renin-angiotensin and renal dopaminergic systems play both synergistic and opposing roles in the regulation of Na+ transport in this nephron segment. Clinical studies have demonstrated that individuals express a "personal salt index" (PSI) that marks whether they are salt-resistant, salt-sensitive, or inverse salt-sensitive. Inverse salt sensitivity results in part from genetic polymorphisms in various Na+ regulatory genes leading to a decrease in natriuretic activity and an increase in renal tubular Na+ reabsorption leading to an increase in BP. This article reviews the potential mechanisms of a new pathophysiologic entity, inverse salt sensitivity of BP, which affects approximately 15% of the general adult population.

Geochemistry and depositional environment of the Mesoproterozoic Xiamaling shales, northern North China

The Mesoproterozoic Xiamaling shales from Xiahuayuan area, southeastern Xuanlong sag, Northern China, were examined the elemental analysis by applying the inductively coupled plasma-mass spectrometry (ICP–MS). The Xiamaling shales have good to excellent oil hydrocarbon generation potential with type II kerogenas demonstrated by high content of alginate macerals, TOC, HI, S1 + S2 and extractable organic matter (EOM). The Xiamaling shales were deposited under a marine environment according to boron (B) (56–111 ppm) and other trace elements concentration, which is consistent with the geological settings. These shales can be classified into three types: (1) Type I is a coastal facies, which is influenced by fresh riverine water and has low B content of 56–61 ppm; (2) Type II is a marginal marine with B content of 73–79 ppm; and (3) type III has high B content of 111 ppm, typical of a brackish, and open marine environment.The Xiamaling shales have high B (>50 ppm), low Na, Ca, Ce, Mn, and rare earth elements (REEs). According to the elemental composition and ratios, the Xiamaling sediments were derived from the felsic source, which has suffered from moderate to strong chemical weathering based on the CIA, ICV, and PIA values. The Xiamaling marine shales were mostly deposited under dysoxic-anoxic conditions. The paleoclimate during the deposition of the Xiamaling shales was warm and humid based on the cross plots of Sr/Ca vs Mn/Ca values and Sr/Cu vs Rb/Sr ratios. Their total REE (ΣREE) contents increase from coastal towards the open marine zone. The Xiamaling shales display a negative Ce anomaly, representative of marine shale, and show a negative Eu anomaly, which is representative of lacustrine oil shale and the Post-Archean Australian Shale (PAAS) and is different from typical marine shale of younger age, indicating the influx of terrestrial sediment.

SALT-SENSITIVITY IN HEALTHY NORMOTENSIVE MEN IS ASSOCIATED WITH IMPAIRED BAROREFLEX SENSITIVITY

Objective: Blood pressure (BP) responses to Na+ intake show great variability, discriminating sodium sensitive (SS) from salt resistant (SR) individuals. The pathophysiology behind salt-sensitivity is still not fully elucidated. A pivotal role for the sympathetic nervous system to BP increase after sodium loading is suggested. Therefore, we aimed to investigate the effect of the sympathovagal balance on Na+-induced BP effects and if Na+-induced effects on sympathetic activation contribute to salt-sensitivity. Design and method: We performed a randomized cross-over study in 31 young healthy men with normal BMI and eGFR. Subjects followed both an 8-day low Na+ diet (LSD, &lt; 50mmol/d) and high Na+ diet (HSD, &gt; 200mmol/d), in 18 subjects the diets were extended to 14-days. SS was defined as an increase of three or more mmHg standardized measured office MAP after HSD. Cardiac-output (CO) and cross correlation baroreflex sensitivity (xBRS) were measured with continuous non-invasive finger photoplethysmography. Systemic vascular resistance (SVR) was calculated as the ratio of MAP by CO. Results: After HSD, SS men (19%) showed a mean 6.2 (±2.1 SD) mmHg increase in MAP. No absolute differences in Na+-induced effects on CO and SVR could be observed between groups. After HSD, xBRS was 34% lower in SS men compared to SR men (Fig1A). Sodium loading resulted in a mean xBRS decrease of 3.4 (±6.5 SD) ms/mmHg in SS men, whilst xBRS increased with 2.3 (±6.3 SD) ms/mmHg in SR men (p = 0.06). HSD xBRS values were significantly correlated with Na+-induced BP changes in the complete group when corrected for age and BMI (Fig1B). Conclusions: Salt-sensitivity of BP in young normotensive men seems to be predominantly driven by changes in sympathovagal balance. The significant correlation between xBRS and delta BP further suggests a continuous relation between sympathetovagal balance and salt exposure. Further studies are needed to unravel pathophysiological mechanisms underlying Na+-effects on sympathetic regulation.