Concentrations Of ZnSO4 Research Articles

Diabetes-induced alteration of metal ion levels declines the activity of MMPs to decrease aortic aneurysm risk.

Diabetes mellitus (DM) links the risk of cardiovascular diseases. Inverse to the enhanced expression of matrix metalloproteinases (MMPs), the development of aortic aneurysm is lower in diabetic population. We examined the hypothesis that DM-induced alteration of metal ion levels declines the activity of MMPs to decrease aortic aneurysm risk. By culturing vascular smooth muscle cells (VSMCs) or macrophages with different concentrations of glucose in the medium, we confirmed that high glucose significantly increased the expression of fibronectin and CTGF in VSMCs, and induced MMP2 expression and MMP9 secretion in macrophages. We also established an abdominal aortic aneurysm model in streptozotocin-induced diabetic mice and evaluated aneurysm development six weeks later. Compared to the healthy controls, diabetic mice had significantly lower levels of Zn2+ and Mg2+ in serum and developed significantly smaller sizes of aneurysms with higher expression of fibronectin and CTGF; but dietary zinc supplementation to diabetic mice effectively neutralized these differences. Gelatin zymography assay indicated that the enzymatic digestion activity of MMP2 was changed under different concentrations of ZnSO4 and MgSO4. Clinical data analysis also confirmed that DM, serum Zn2+ level, and aortic aneurysm risk closely correlated with each other. It seems that DM-induced alteration of metal ion levels declines the activity of MMPs to negate aortic aneurysm development. Our data provide novel mechanistical insight and therapeutic strategy for aortic aneurysms.

Effects of Dietary Zinc Chloride and Zinc Sulfate on Life History Performance and Hemolymph Metabolism of Spodoptera litura (Lepidoptera: Noctuidae).

Zinc is an essential micronutrient crucial in various biological processes of an organism. However, the effects of zinc vary depending on its chemical form. Therefore, the aim of this study was to conduct a comparative analysis of the life history performances and hemolymph metabolism of Spodoptera litura exposed to different concentrations of dietary zinc chloride (ZnCl2) and zinc sulfate (ZnSO4), utilizing two-sex life tables and untargeted metabolomics. The preadult survival rate of S. litura significantly decreased, while the preadult developmental period of S. litura was prolonged as the dietary ZnCl2 concentration increased. However, the fecundity of S. litura at 50 mg/kg dietary ZnCl2 was significantly increased. The intrinsic rate of increase (r) and the finite rate of increase (λ) in S. litura in the control group (CK, no exogenous ZnCl2 or ZnSO4 added) and with 50 mg/kg dietary ZnCl2 were significantly higher than those at 100 mg/kg, 200 mg/kg, and 300 mg/kg. Dietary ZnSO4 exerts a devastating effect on the survival of S. litura. Even at the lowest concentration of 50 mg/kg dietary ZnSO4, only 1% of S. litura could complete the entire life cycle. Furthermore, as the dietary ZnSO4 concentration increased, the developmental stage achievable by the S. litura larvae declined. High-throughput untargeted metabolomics demonstrated that both 100 mg/kg dietary ZnCl2 and ZnSO4 decreased the hemolymph vitamins levels and increased the vitamin C content, thereby helping S. litura larvae to counteract the stress induced by ZnCl2 and ZnSO4. Simultaneously, dietary ZnCl2 obstructed the chitin synthesis pathway in the hemolymph of S. litura, thus extending the developmental period of S. litura larvae. These results indicate that low concentrations of Zn2+ positively impact populations of S. litura, but the effectiveness and toxicity of Zn depend on its chemical form and concentration.

Exploration of the structural and electrical characteristics and solar cell applications of an electrolyte membrane derived from acacia gum

The natural and eco-friendly solid-state electrolytes were prepared using varying concentrations (wt%) of ZnSO4.7H2O salt and pure acacia gum through the solution cast method. Multiple analytical methods were employed to characterize the resulting acacia gum electrolyte samples. XRD analysis confirmed the increased presence of the amorphous phase with the introduction of salt. FTIR analysis explored the formation of interlinking bands and their complex nature upon salt incorporation. The ionic conductivity was found from room temperature (RT) to 100 °C range. The optimized high ionic conductivity value was found to be 1.11 × 10−4 S/cm at 100 °C for the electrolyte composed of 70 wt% acacia gum and 30 wt% ZnSO4.7H2O, while at RT it was 1.06 × 10−5 S/cm for the same composition. Activation energy values fell within the 0.6–0.92 eV range for all samples. Complex dielectric (real and imaginary) and complex electric modulus analyses were conducted. Dielectric permittivity and electrical modulus analyses revealed a significant interaction between the segmental movements of acacia gum and salt ions. Ionic relaxation processes were explored in terms of conductivity relaxation time using the electrical modulus. The presence of a long tail in the complex dielectric modulus study indicated that the acacia-based solid electrolyte displayed favorable capacitance properties. Further, the Solar Cell (dye-sensitized solar cell) device was fabricated with (Acacia gum + ZnSO4.7H2O) electrolyte. The current density-voltage (J-V) characteristics of the prepared device were investigated. The outstanding results were optimized in the present work, Voc = 0.81 V, Jsc = 9.56 mA/cm2, Fill Factor of 0.67, and optimum power conversion efficiency ƞ = 5.17 % for the electrolyte composed of 70 wt% acacia gum and 30 wt% ZnSO4.7H2O device.

Laser diagnostics of micellar nanoreactors in ZnSO4/water/AOT/heptane reverse microemulsion system

In the article, for the first time, a method has been developed for remote monitoring of the composition of the reaction medium of micellar nanoreactors and for determining the parameters of nanoparticles during their synthesis using Raman spectroscopy. The sensitivity of spectral characteristics to changes in the size of nanoreactors and the concentration of the nanoparticle precursor in reverse ZnSO4/water/AOT/heptane microemulsions has been experimentally established. It has been shown that the intensity of the band of symmetrical S-O stretching vibrations in the Raman spectrum of the ZnSO4/water/AOT/heptane microemulsion can be used to determine the concentration of ZnSO4 in the micelle cores with the accuracy of 2.4 %. The calibration dependence of the center of mass position of the symmetrical O–H stretching vibrations band of the specified microemulsion on the micelles diameter ensures the determination of the sizes of micellar nanoreactors with an accuracy of 11 %.

Revealing the Effects of Polymer Additives on Zn Dendrite Suppression in Aqueous Zn Batteries via in-Situ EC-AFM

Polyethylene glycol (PEO) is a commonly used polymer in the field of batteries for achieving flat and uniform electrodes to enhance the performance of batteries, such as lithium batteries and zinc (Zn) batteries. However, the impact of PEO on the electrochemical deposition of Zn metal on electrodes remains uncertain. In this study, we selected ZnSO4 solution as electrolyte and copper (Cu) substrates as electrodes, which are widely applied in Zn batteries. We used in situ electrochemical atomic force microscopy (EC-AFM) to observe the nucleation and growth of Zn metal plates on the Cu substrate in the presence of different concentrations of ZnSO4 and PEO additives. Our results indicate that PEO biases the crystallographic orientation of the initially deposited Zn metal nuclei, but does not have an obvious influence on subsequent growth. Based on our findings, we hypothesize that PEO primarily interacts with the Cu substrate to adjust the interfacial energy of the Cu-electrolyte interfaces. In contrast, due to the lack of apparent change in the Zn growth rate, we postulate that PEO does not affect the delivery rate of Zn2+ to the electrode surface. The consistent aspect ratio of the Zn plates combined with the lack of an effect on growth rates further suggests that PEO does not interact significantly with the surface of the newly formed Zn plates. The Zn metal will undergo surface reorganization in a mildly acidic aqueous solution as a result of oxidation of Zn, which is not affected by PEO adsorption. Our findings provide both insight into the underlying mechanism by which PEO promotes electrode flattening in Zn batteries and a standardized protocol for elucidating the impact of additives on the morphological evolution of interfaces during electrochemical deposition.Work by C.O. was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Enhancing zinc biofortification and mitigating cadmium toxicity in soil–earthworm–spinach systems using different zinc sources

Cadmium (Cd) pollution poses significant threats to soil organisms and human health by contaminating the food chain. This study aimed to assess the impact of various concentrations (50, 250, and 500 mg·kg–1) of zinc oxide nanoparticles (ZnO NPs), bulk ZnO, and ZnSO4 on morphological changes and toxic effects of Cd in the presence of earthworms and spinach. The results showed that Zn application markedly improved spinach growth parameters (such as fresh weight, plant height, root length, and root-specific surface area) and root morphology while significantly reducing Cd concentration and Cd bioconcentration factors (BCF-Cd) in spinach and earthworms, with ZnO NPs exhibiting the most pronounced effects. Earthworm, spinach root, and shoot Cd concentration decreased by 82.3 %, 77.0 %, and 75.6 %, respectively, compared to CK. Sequential-step extraction (BCR) analysis revealed a shift in soil Cd from stable to available forms, consistent with the available Cd (DTPA-Cd) results. All Zn treatments significantly reduced Cd accumulation, alleviated Cd-induced stress, and promoted spinach growth, with ZnO NPs demonstrating the highest Cd reduction and Zn bioaugmentation efficiencies compared to bulk ZnO and ZnSO4 at equivalent concentrations. Therefore, ZnO NPs offer a safer and more effective option for agricultural production and soil heavy metal pollution management than other Zn fertilizers.

Effect of Foliar Spray of NPK, Borax, ZnSO\(_4\) & MgSO\(_4\) on Storage of Strawberry (Fragaria annanassa Duch.) cv. Winter Dawn

This study identified the synergistic effect of NPK, Borax, ZnSO4 and MgSO4 with different concentrations on the postharvest quality and shelf life of strawberry stored at ambient conditions. This study was conducted in completely randomized Block design. Strawberry fruits were treated with different concentration of NPK, Borax, ZnSO4 and MgSO4 and stored at ambient temperature for 4 days. Changes in fruit’s physiological loss of weight, firmness, total soluble solid, titrable acidity, and ascorbic acid were periodically recorded. The results indicated that the treatment T8 (NPK @0.5% + Borax @0.25% + Znso4 @0.25%+ Mgso4 @0.25%) significantly reduced the decrease of physiological loss of weight, total soluble solids, titrable acidity, ascorbic acid, reducing sugar, non- reducing sugar and total sugar content. The results showed that treatment T8 (NPK @0.5% + Borax @0.25% + Znso4 @0.25%+ Mgso4 @0.25%) is the most effective treatment for improving the postharvest quality and prolong the shelf life of strawberry when stored at ambient condition.

Enhancement of Frozen-Thawed Human Sperm Quality with Zinc as a Cryoprotective Additive.

BACKGROUND Cryopreservation preserves male fertility, crucial in oncology, advanced age, and infertility. However, it damages sperm motility, membrane, and DNA. Zinc (Zn), an antioxidant, shows promise in improving sperm quality after thawing, highlighting its potential as a cryoprotectant in reproductive medicine. MATERIAL AND METHODS Gradient concentration of ZnSO₄ (0, 12.5, 25, 50, and 100 µM) was added in the Glycerol-egg yolk-citrate (GEYC) cryopreservative medium as an extender. Alterations in sperm viability and motility parameters after cryopreservation were detected in each group. Sperm plasma membrane integrity (PMI), acrosome integrity (ACR), DNA fragment index (DFI), and changes in sperm mitochondrial function were examined, including: mitochondrial potential (MMP), sperm reactive oxygen species (ROS), and sperm ATP. RESULTS We found that 50 µM ZnSO₄ was the most effective for the curvilinear velocity (VCL) and the average path velocity (VAP) of sperm after cryo-resuscitation. Compared to the Zn-free group, sperm plasma membrane integrity (PMI) was increased, DNA fragmentation index (DFI) was decreased, reactive oxygen species (ROS) was reduced, and mitochondrial membrane potential (MMP) was increased after cryorevival in the presence of 50 µM ZnSO₄. CONCLUSIONS Zn ion is one of the antioxidants in the cell. The results of our current clinical study are sufficient to demonstrate that Zn can improve preserves sperm quality during cryopreservation when added to GEYC. The addition of 50 µM ZnSO₄ increased curve velocity, mean path velocity, sperm survival (or plasma membrane integrity), and mitochondrial membrane potential while reducing ROS production and DNA breaks compared to GEYC thawed without ZnSO₄.

Physicochemical characteristics of pomegranate fruits as affected by foliar application of potassium and zinc

Foliar application of mineral nutrients can considerably improve fruit yield and quality. In this study, the effects of K and Zn application by spraying on leaf mineral contents, and some physical and biochemical characteristics of pomegranate fruits cv. ‘Malas Saveh’ were investigated. The mineral treatments were three concentrations of K2SO4 (0, 1, and 2%) and three concentrations of ZnSO4 (0, 0.5, and 1%). The solutions were applied in 2020–2021 and in four times: the first application was during the time of flowering and rest three applications were applied at two-week intervals. The results showed that leaves of trees fed with different concentrations of K2SO4 and ZnSO4 accumulated higher concentrations of N, P K, Zn, Fe, and Mn than those untreated. Pomegranate trees treated with the mineral treatments had higher chlorophyll a and total chlorophyll. Applying most mineral treatments, especially 2% K2SO4+0.5% ZnSO4, significantly increased the fruit yield, fruit diameter, fruit length, aril percentage, aril/skin, the weight of 100 arils, and juice content of 100 g arils, but reduced the cracking percentage, skin thickness, skin percentage and firmness of fruits. Moreover, fruits of pomegranate trees treated with the most mineral treatments and especially 2% K2SO4+0.5% ZnSO4, showed a greater level of TSS (total soluble solids), TSS/TA (total soluble solids/titratable acidity), anthocyanin, total phenol, flavonoid, antioxidant activity, and vitamin C, and a lower level of TA. The study results evidenced that K and Zn application by spraying has a high potential for improving fruit yield and quality of pomegranate.

Effect of Seed Priming on Germination, Seedling Emergence and Development of Spring Rice Var. Hardinath-1

Poor germination percentage and non-uniform seedling emergence and establishment are major causes of low rice yield in water-deficit arid ecosystems. A seed priming study with a low concentration of MoP, DAP, urea, vitamin C, ZnSO4, sucrose, NaCl, and hydro priming was conducted to assess the seed germination, seedling emergence, establishment, and seedling growth of the spring rice variety Hardinath-1. The experiment was conducted using a completely randomized design with three replications. Two test sets of experiments were carried out using blotting paper rolls and separate sand trays. Germination was observed at intervals of 24 hours up to 7 days, and germination and growth parameters were monitored. The results showed that germination (88.67%) and seedling emergence (88.67%) were high in vitamin C at 7 days after sowing (DAS). Germination energy (81%), germination speed (91.78%), and vigor index (91.78) were higher with seed priming of MoP. The lowest germination (56.44%) was observed with the priming of urea. At 30 DAS, the longest shoot length (19.93 cm) and longest root length (11.79 cm) were observed with the priming of ZnSO4. The highest seedling fresh weight (0.75 g) and dry weight (0.16 g), the highest number of leaves (3.57), and the longest leaf length (11.97 cm) were found with the priming of MoP, NaCl, and ZnSO4, respectively. However, the lowest seedling growth parameters were observed in the control priming. The overall results revealed that seed priming with MoP is an effective tool to enhance the germination percentage and seedling establishment of rice. SAARC J. Agric., 21(2): 81-93 (2023)

Effect of Foliar Spraying of Nano Zno on Qualitative and Physical Parameters of Tomato Grown in Polybags

Background: Tomato (Solanum lycopersicum L.) is the main vegetable crop extensively grown all over the globe. Tomato requires both major and micronutrients for its proper plant growth. Nano fertilizers are preferred largely due to their efficiency and environmentally friendly nature compared to conventional chemical fertilizers. Nano fertilizers are preferred largely due to their efficiency and environmentally friendly nature compared to conventional chemical fertilizers. The use of nano fertilizers is expected to maintain better soil fertility and provide greater crop yields.
 Methods: A polybag experiment was conducted during Kharif, 2020-21 at Agricultural College, Palem, PJTSAU, in a completely randomized design (CRD) with fourteen treatments comprising different concentrations of nano ZnO (50, 100, 250, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250 and 2500 ppm), ZnSO4 and control.
 Results: Foliar spraying of nano ZnO 1000 ppm recorded the lowest total soluble solids (4.00 0brix), highest ascorbic acid (23.71 mg 100g-1), highest titrable acidity (0.48%), lowest percentage of total sugars (2.80%), lowest percentage of reducing sugars (2.48%), highest percentage (0.32%) of non-reducing sugars and highest value of lycopene content (6.64 mg 100g-1), maximum shelf life (11.67 days) and firmness (3.05 kg cm-2). On 3rd, 6th and 9th day after harvest, same treatment recorded minimum physiological loss in weight (3.64%, 6.36% and 8.51%).

Effects of ZnSO4 concentration on the high-rate deposition of CBD-Zn(O,S) buffer layer for Cu(In,Ga)Se2 thin-film solar cells

To utilize eco-friendly materials in Cu(In,Ga)Se2 (CIGS) thin-film solar cells, a Zn-based buffer layer has been adopted to replace the conventional CdS buffer layer. Buffer layers can be grown using a variety of techniques, with chemical bath deposition (CBD) generally used for the preparation of the Zn(O,S) buffer layer. The growth rate of the CBD-Zn(O,S) buffer layer is determined by the dissociation rate of S during chemical reaction between Zn and S ions. Thiourea (TU) is a conventional precursor of S, but it suffers from poor dissociation rate of S, leading to prolonged layer deposition times. In this study, we replaced TU with thioacetamide (TAA), thereby drastically shortening the deposition time from 80 min (TU) to 7 min (TAA). Furthermore, incorporating Zn with S ions is known to be difficult owing to the high-speed release of S ions from TAA. However, by adjusting the molar concentration of ZnSO4, we discovered a process to effectively form the Zn–S bonds for the CBD-Zn(O,S) buffer layer. The efficiency of the CIGS thin-film solar cell shows the best performance at a ZnSO4 concentration of 0.05 M, which rivals the performance of the TU base process. The physical and chemical properties of CBD-Zn(O,S) grown at a high deposition rate using TAA were examined as a function of ZnSO4 molar concentration. We proposed a growth model that accounts for the changes in film thickness and surface morphology evolution, both of which depend on the ZnSO4 concentration. Additionally, to investigate the p–n junction properties in terms of device operation, we elucidated the band alignment at the CIGS/CBD-Zn(O,S) interface, concentrating on the interfacial barrier height. It is empirically demonstrated that a lower ΔEC value improves the solar cell operation.

Promoting Homogeneous Zinc-Ion Transfer Through Preferential Ion Coordination Effect in Gel Electrolyte for Stable Zinc Metal Batteries.

Aqueous zinc metal batteries (AZMBs) are emerging energy storage systems that are poised to replace conventional lithium-ion batteries owing to their intrinsic safety, facile manufacturing process, economic benefits, and superior ionic conductivity. However, the issues of inferior anode reversibility and dendritic plating during operation remain challenging for the practical use of AZMBs. Herein, a gel electrolyte based on zwitterionic poly(sulfobetaine methacrylate) (poly(SBMA)) dissolved with different concentrations of ZnSO4 is proposed. Two-dimensional correlation spectroscopy based on Raman analysis reveals an enhanced interaction priority between the polar groups in SBMA and the dissolved ions as electrolyte concentration increases, which establishes a robust interaction and renders homogeneous ion distribution. Attributable to the modified coordination, zwitterionic gel polymer electrolyte with 5molkg-1 of ZnSO4 (ZGPE-5) facilitates stable zinc deposition and improves anode reversibility. By taking advantage of preferential coordination, a symmetrical cell evaluation employing ZGPE-5 demonstrates a cycle life over 3600 h, where ZGPE-5 also exerts a beneficial effect on the full cell cycling when assembled with Zn0.25 V2 O5 cathode. This study elucidates changes in the internal ion behavior that are dependent on electrolyte concentrations and pave the way for durable AZMBs.

Determination of the solubility of MgSO4 in the Zinc hydrometallurgy system within the temperature range of 263.15 K–293.15 K

ABSTRACT Solid–liquid equilibrium solubility of magnesium sulphate (MgSO4) is essential for designing and optimising the removal and recovery of magnesium (Mg) from standard zinc (Zn) hydrometallurgy systems via freeze crystallization. In this study, the solubility data of MgSO4 in ternary system MgSO4-H2SO4-H2O and quaternary system MgSO4-ZnSO4-H2SO4-H2O were determined in different zinc sulphate (ZnSO4) concentrations and sulphuric acid (H2SO4) concentrations through the isothermal equilibrium method within the temperature range from 263.15–293.15 K. The results indicated that the solubility of MgSO4 decreased with decreasing temperature and increasing concentrations of H2SO4 and ZnSO4. Furthermore, the modified Apelblat equation was applied to correlate the experimental solubility data, yielding results consistent with the experimental findings. Furthermore, X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy SEM-EDS analysis results indicated that the main phases of the equilibrium solid consist of mixed crystallization products of Zn sulphate heptahydrate (MgSO4·7H2O) and Mg sulphate heptahydrate (ZnSO4·7H2O). The microstructure of the equilibrium solid was affected by the sulphate concentration.

Strategies for Improving Lignocellulosic Butanol Production and Recovery in ABE Fermentation by Tailoring Clostridia Metabolic Perturbations

The present study investigates approaches to enhance bio-butanol production using lignocellulosic feedstock via supplements of metabolism perturbation. Traditionally, bio-butanol has been produced through chemical synthesis in a process known as acetone–butanol–ethanol (ABE) fermentation. Today, biochemical techniques involving bacterial strains capable of producing butanol are used with renewable sources of biomass. In this study, a stepwise approach was tailored for metabolic perturbations to maximize butanol production from pure sugar and lignocellulosic feedstock as a reference model fermentation. In preliminary investigations, impacts of CaCO3, furfural and methyl red on cell growth, sugar utilization, acid production and butanol production were evaluated in glucose feedstock and xylose feedstock. Following the preliminary investigation, with supplementation of 4 g/L CaCO3, the concentrations of furan derivatives (75% furfural and 25% HMF) and ZnSO4 were optimized for maximal butanol production from glucose and xylose feedstocks, respectively. A final experiment of butanol production was concluded using lignocellulosic feedstock hydrolysate normally containing 0.5~1.5 g/L furan derivatives under optimized conditions of 2 mg/L ZnSO4 and 4 g/L CaCO3. Under optimized conditions, butanol production exceeded 10 g/L in wheat straw hydrolysate, which was significantly higher than that obtained in the absence of ZnSO4 and CaCO3. As compared to the traditional lignocellulosic feedstock post-treatment method, the metabolic perturbations method shows advantages in terms of productivity and economics.

Controllable and innovative preparation of Zn(O,S) buffer layers for CIGS thin film solar cells

The band gap of CdS (Eg = 2.4 eV) was narrow, which made it unable to transmit short-wave sunlight through the CIGS absorber layer. Zn(O,S) thin film, prepared by doping O into ZnS, had a wider band gap, and the raw material was green and non-toxic, making it suitable as a buffer layer for solar cells. However, CBD-Zn(O,S) usually takes longer than CdS deposition. In this work, By shortening the deposition time through the fast hydrolysis of TAA. Na3NTA was added in the solutions to improve the quality of Zn(O,S) thin films. The effect of Na3NTA concentration on the complex ion contents was investigated. When Na3NTA was added at a concentration of 0.04 M along with TAA (0.04 M), the film had a high T% of 88.6%, Eg of 3.76 eV, and a dense grain distribution. ZnS and ZnO grew at (111) and (100) crystals, respectively. Raman and XPS analyses showed the existence of Zn–S and Zn–O bonds, indicating the high crystalline quality of the Zn(O,S) thin films prepared with CBD. Finally, when the optimal concentrations of ZnSO4, NH4OH, Na3NTA, and TAA were 0.04 M, 0.48 M, 0.04 M, and 0.04 M, respectively, the prepared Zn(O,S) thin films could be used as a cadmium-free buffer layer for solar cells.

Mechanism of Zn alleviates Cd toxicity in mangrove plants (Kandelia obovata).

Cadmium (Cd) pollution is very common and serious in mangrove ecosystems in China. Zinc (Zn) has been used to reduce Cd accumulation in plants, and phenolic acid metabolism plays an important role in plant response to stress. In present study, in order to clarify whether Zn alleviates Cd toxicity in mangrove plants through phenolic acid metabolism, the Cd-contaminated Kandelia obovata plants were treated with different concentrations of (0, 80,300, and 400 mg·kg-1) ZnSO4 in a set of pot experiments and the biomass, the contents of Cd, Zn, soluble sugar, chlorophyll and the activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP), l-phenylalanine ammonia-lyase (PAL), shikimic acid dehydrogenase (SKDH), cinnamyl alcohol dehydrogenase (CAD) and polyphenol oxidase (PPO) in the leaves were analyzed. The results showed that Cd contents in the leaves of Kandelia obovata ranged from 0.077 to 0.197 mg·kg-1 under different treatments, and Zn contents ranged from 90.260 to 114.447 mg·kg-1. Low-dose ZnSO4 treatment (80 mg·kg-1) performed significant positive effects on the biomass, phenolic acid metabolism-related enzyme activities, antioxidant capacity, and chlorophyll and soluble sugar contents in the leaves of Cd-contaminated mangrove plants. At the meantime, the addition of low-dose ZnSO4 promoted the biosynthesis of hydroxycinnamic acid, hydroxybenzoic acid, and enhanced the plant antioxidant capacity, thus alleviated Cd toxicity in mangrove plants.

The balance between gyrase and topoisomerase I activities determines levels of supercoiling, nucleoid compaction, and viability in bacteria.

Two enzymes are responsible for maintaining supercoiling in the human pathogen Streptococcus pneumoniae, gyrase (GyrA2GyrB2) and topoisomerase I. To attain diverse levels of topoisomerase I (TopoI, encoded by topA), two isogenic strains derived from wild-type strain R6 were constructed: PZn topA, carrying an ectopic topA copy under the control of the ZnSO4-regulated PZn promoter and its derivative ΔtopAPZn topA, which carries a topA deletion at its native chromosomal location. We estimated the number of TopoI and GyrA molecules per cell by using Western-blot and CFUs counting, and correlated these values with supercoiling levels. Supercoiling was estimated in two ways. We used classical 2D-agarose gel electrophoresis of plasmid topoisomers to determine supercoiling density (σ) and we measured compaction of nucleoids using for the first time super-resolution confocal microscopy. Notably, we observed a good correlation between both supercoiling calculations. In R6, with σ = -0.057, the average number of GyrA molecules per cell (2,184) was higher than that of TopoI (1,432), being the GyrA:TopoI proportion of 1:0.65. In ΔtopAPZn topA, the number of TopoI molecules depended, as expected, on ZnSO4 concentration in the culture media, being the proportions of GyrA:TopoI molecules in 75, 150, and 300 μM ZnSO4 of 1:0.43, 1:0.47, and 1:0.63, respectively, which allowed normal supercoiling and growth. However, in the absence of ZnSO4, a higher GyrA:TopoI ratio (1:0.09) caused hyper-supercoiling (σ = -0.086) and lethality. Likewise, growth of ΔtopAPZn topA in the absence of ZnSO4 was restored when gyrase was inhibited with novobiocin, coincidentally with the resolution of hyper-supercoiling (σ change from -0.080 to -0.068). Given that TopoI is a monomer and two molecules of GyrA are present in the gyrase heterotetramer, the gyrase:TopoI enzymes proportion would be 1:1.30 (wild type R6) or of 1:1.26-0.86 (ΔtopAPZn topA under viable conditions). Higher proportions, such as 1:0.18 observed in ΔtopAPZn topA in the absence of ZnSO4 yielded to hyper-supercoiling and lethality. These results support a role of the equilibrium between gyrase and TopoI activities in supercoiling maintenance, nucleoid compaction, and viability. Our results shed new light on the mechanism of action of topoisomerase-targeting antibiotics, paving the way for the use of combination therapies.

Range Findings of Lethal Concentration of Zinc Sulfate Heptahydrate (ZnSO4.7H2O) to Juvenile Red Tilapia

An acute toxicity study was conducted to determine the range of lethal concentration of zinc sulfate heptahydrate (ZnSO4.7H2O) to juvenile red tilapia (Oreochromis sp.). The mortality of the fish was recorded at 24, 48, 72, and 96 hours of study. The lethal concentration of ZnSO4.7H2O that caused 50% mortality (LC50) was 48.7, 40.0, 34.6, and 33.1 mg/L for 24, 48, 72, and 96 hours, respectively. Meanwhile, the lethal concentration that caused 99% mortality (LC99) was 116.7, 108.7, 76.2, and 69.9 mg/L for 24, 48, 72, and 96 hours, respectively. The Probit analysis with a 95% confidence interval is used to determine the range of lethal concentration of ZnSO4.7H2O for 24, 48, 72, and 96 hours of toxicity study. The result shows that the lethal concentration of ZnSO4.7H2O decreased over time indicating that the low concentration could become lethal to juvenile red tilapia when exposed for longer periods and act as a preliminary study for further study.

Reversible switching and stability of the epigenetic memory system in bacteria.

In previous work, we have developed a DNA methylation-based epigenetic memory system that operates in Escherichia coli to detect environmental signals, trigger a phenotypic switch of the cells and store the information in DNA methylation. The system is based on the CcrM DNA methyltransferase and a synthetic zinc finger (ZnF4), which binds DNA in a CcrM methylation-dependent manner and functions as a repressor for a ccrM gene expressed together with an egfp reporter gene. Here, we developed a reversible reset for this memory system by adding an increased concentration of ZnSO4 to the bacterial cultivation medium and demonstrate that one bacterial culture could be reversibly switched ON and OFF in several cycles. We show that a previously developed differential equationmodel of the memory system can also describe the new data. Then, we studied the long-term stability of the ON-state of the system over approximately 100 cell divisions showing a gradual loss of ON-state signal starting after 4 days of cultivation that is caused by individual cells switching from an ON- into the OFF-state. Over time, the methylation of the ZnF4-binding sites is not fully maintained leading to an increased OFF switching probability of cells, because stronger binding of ZnF4 to partially demethylated operator sites leads to further reductions in the cellular concentrations of CcrM. These data will support future design to further stabilize the ON-state and enforce the binary switching behaviour of the system. Together with the development of a reversible OFF switch, our new findings strongly increase the capabilities of bacterial epigenetic biosensors.