Different Concentrations Of Zn Research Articles

Spectral variations associated with anthocyanin accumulation; an apt tool to evaluate zinc stress in Zea mays L.

ABSTRACT The correlation between anthocyanins content and accumulation of zinc (Zn) in leaves of Zea mays was investigated and this was considered as a mode of assessing the intensity of Zn toxicity. Characterisation and quantification of leaf pigments were done in 45 d old maize plants exposed to different concentrations of Zn (0.0, 0.65, 1.30, 1.95 g Zn Kg−1 soil), and the enhancement in the accumulation of anthocyanins and degradation of chlorophyll was detected by the spectral analysis performed in the leaf extract of plants as the Zn content in the shoot increases. The role of anthocyanins in safeguarding photosynthesis and chelation of Zn was critically evaluated using chlorophyll a fluorescence responses and computational DFT-B3LYP structural analysis of anthocyanins-Zn complex has been performed using 6-311++ G (df, p) basis set. It was concluded that the accumulation of anthocyanins can act as an indicator of the intensity of Zn stress and this anthocyanins have a lesser potential to maintain photosynthetic efficiency in Z. mays, but plays a prominent role in metal chelation as the anthocyanins-Zn complex is a stable molecule.

Mitigation of cadmium toxicity by zinc in juvenile cacao: Physiological, biochemical, molecular and micromorphological responses

Cadmium (Cd) is a trace metal without essential biological function due to its high toxicity to plants, animals and humans, even at low concentrations. On the other hand, Zn is an essential nutrient and plays important metabolic functions in plants. The study of the interaction between essential and a nonessential element may be important for understanding, analyzing and improving the defense strategies adapted by plants. The main objective of this work was to evaluate the mitigation of Cd toxicity by Zn in young plants of the CCN 51 cocoa genotype, grown in soil with different concentrations of Zn, Cd and Zn + Cd, through physiological, biochemical, molecular and micro-morphological responses. It was verified that high concentrations of Zn, Cd and Zn + Cd in the soil promoted alterations in the enzymatic and non-enzymatic antioxidative metabolism and expression of genes. This was demonstrated by increase in the activity of antioxidative enzymes, proline content and reduction in lipid peroxidation. Leaf gas exchange was affected at the highest soil Cd concentrations (0.4, 0.6 and 0.8 mmol Cd kg−1 soil) combined with different soil Zn concentrations (0.4, 0.8, 1.2 and 1.6 mmol kg-1 soil), resulting in a decrease in CO2 fixation. The higher concentration of soil Cd (0.8 mmol kg−1 soil), together with the intermediate concentrations of soil Zn + Cd (0.8 + 0.4 and 0.4 + 0.6 mmol kg−1 soil), promoted reduction of the thickness of the leaf mesophyll and, consequently, led to decrease of the leaf gas exchange. It was observed a hormesis effect due to high photosynthetic activity in low Cd concentration. The increase in Cd concentration in the soil altered the uptake of Cd and Zn by the roots of the CCN 51 cocoa genotype. The increase of Zn concentration in the soil promoted the decrease of the Cd uptake by the root system of the plants and thereby reduced the transport of Cd to the leaves. Part of Cd uptake by the plant's root system was immobilized in roots tissues, as a tolerance strategy, preventing that it was transported to the aerial part. The increase of Zn + Cd concentration in the soil did not influence the accumulation of Zn in the leaves of the young plants of the CCN 51 cocoa genotype.

Nrf2 participates in the anti-apoptotic role of zinc in Type 2 diabetic nephropathy through Wnt/β-catenin signaling pathway

Zinc (Zn), as an essential trace element, has been approved to serve many roles in diabetic studies. Also Zn deficiency will aggravate renal damage in diabetes through suppression of nuclear factor-erythroid 2-related factor 2 (Nrf2) expression and function. The purpose of this study was to illustrate the role of Zn in renal apoptosis in diabetes and whether Nrf2 participated in the process. Type 2 diabetes mice model was induced by a single dose of streptozotocin (STZ) injection after high-fat diet (HFD) feeding for 3 months, then the mice were given diets supplemented with different concentrations of Zn (control, 30 ppm; low-concentration, 0.85 ppm). After 12-week treatment, morphology and associated protein expressions were examined. The results showed that low Zn diet significantly aggravated the level of renal apoptosis during diabetes, performed as the upregulation of caspase-3 expression. In addition, either low Zn diet or diabetes or both dramatically decreased the expression of Nrf2 and P-AKT in kidney. Moreover, the expression of β-catenin in kidney was increased markedly in diabetic groups. Mechanistic study applying human renal tubular epithelial cells (HK11) confirmed the role of Nrf2, as silencing Nrf2 expression abolished Zn supplementation protection against high sugar + high fat + low Zn-induced apoptosis and downregulation of β-catenin expression. All these results suggest that Nrf2 plays a key role in Zn protection against Type 2 diabetes induced renal apoptosis, which might be through Wnt/β-catenin signaling pathway.

Zinc Deficiency Aggravation of ROS and Inflammatory Injury Leading to Renal Fibrosis in Mice.

Zinc (Zn) is a trace element with a variety of anti-inflammatory and antioxidant effects. Zn deficiency is related to tissue fibrosis. The present study was designed to investigate the effect of Zn on renal fibrosis. Mouse models were successfully established by feeding mice diets with different concentrations of Zn. Zn deficiency induced a decrease in Zn levels in kidney tissue. The results also revealed renal vasodilation, hyperemia, and inflammatory cell infiltration, and the levels of creatinine and urea nitrogen were increased. Furthermore, the TUNEL results showed a large degree of renal cell necrosis caused by Zn deficiency. Meanwhile, the corresponding antioxidant and anti-inflammatory regulators (MT-1, MT-2, Nrf2, and TGF-β1) were detected by RT-PCR, showing that the expression of MT-1, MT-2, and Nrf2 decreased but that TGF-β1 expression increased. The results of Sirius red staining proved that the expression of collagen was increased by Zn deficiency. The immunohistochemical experiments found that the expression of α-smooth muscle actin (α-SMA) increased. ELISA showed that the expression of Collagen I, III, and IV; fibronectin (FN); and inflammatory factors (TNF-α and IL-1β) were remarkably increased. The expression of MMP-1, MMP-2, MMP-3, MMP-7, MMP-9, MMP-12, and TIMP-1, which are extracellular matrix-regulating molecules, was detected by RT-PCR. The results showed that the expression of TIMPs was increased but that the expression of MMPs was decreased. We also obtained consistent results in vivo. All the experimental results indicated that Zn deficiency could aggravate fibrosis by increasing inflammation in the kidney.

Effects of Copper and Zinc Application on the Oil Palm Root Morphology and Epidermis Cell Size

The growth of oil palm is highly dependent on the availability of nutrients, supplied through fertilizers. This is especially true for peat soils where there is a lack of Zn and Cu due to the soil being deficient of mineral and clay content. The deficiency of Zn and Cu has been found to inhibit oil palm plant and root growth. The objective of this study is to determine the effect of different concentration of Zn and Cu chelates on the root development of oil palm roots cell walls. The oil palm seedlings were harvested after two different growing periods; the first harvest was conducted after three months of planting while the second harvest was after 6 months of planting. The harvested oil palm seedlings were measured for root length, root thickness and root surface area. The best root growth for the copper treatments was with concentrations of 8.00 mg Cu/palm. The cell epidermis size and cortex cells of the oil palm seedlings in this treatment was the smallest, meaning that it did not experience any Cu toxicity, while it had the longest root length, root surface area, root fresh weight and root dry weight. For the zinc treatments, the best root growth was at 5.00 mg/palm. This is because in this treatment, the oil palm seedlings achieved the highest root length, root surface area, root fresh weight and root dry weight. This means that the best concentration of Cu to promote root growth of oil palm seedlings is 8.00 mg Cu/palm while the best concentration of Zn was 5.00 mg Zn/palm. Further research needs to also be conducted using a combination of both Zn and Cu applications at the same time, to determine if the combined micronutrients had different effects on the oil palm seedlings roots growth.

Zinc toxicity alters the photosynthetic response of red alga Pyropia yezoensis to ocean acidification.

The globally changing environmental climate, ocean acidification, and heavy metal pollution are of increasing concern. However, studies investigating the combined effects of ocean acidification and zinc (Zn) exposure on macroalgae are very scarce. In this study, the photosynthetic performance of the red alga Pyropia yezoensis was examined under three different concentrations of Zn (control, 25 (medium), and 100 (high) μg L-1) and pCO2 (400 (ambient) and 1000 (high) μatm). The results showed that higher Zn concentrations resulted in increased toxicity for P. yezoensis, while ocean acidification alleviated this negative effect. Ocean acidification increased the relative growth rate of thalli under both medium and high Zn concentrations. The net photosynthetic rate and respiratory rate of thalli also significantly increased in response under ocean acidification, when thalli were cultured under both medium and high Zn concentrations. Malondialdehyde levels decreased under ocean acidification, compared to ambient CO2 conditions and either medium or high Zn concentrations. The activity of superoxide dismutase increased in response to high Zn concentrations, which was particularly apparent at high Zn concentration and ocean acidification. Immunoblotting tests showed that ocean acidification increased D1 removal, with increasing expression levels of the PSII reaction center proteins D2, CP47, and RbcL. These results suggested that ocean acidification could alleviate the damage caused by Zn exposure, thus providing a theoretical basis for a better prediction of the impact of global climate change and heavy metal contamination on marine primary productivity in the form of seaweeds.

The response of candy barrel cactus to zinc contamination is modulated by its rhizospheric microbiota

In order to better understand the mechanism of tolerance to zinc contamination, a potentially toxic element, it is relevant to analyze its effects on the rhizospheric microbiota of plants with a high tolerance to environmental stress such as cacti species. In this work, the risk for soil contamination with zinc, its effect on bacterial diversity, microbial carbon, abundance of diazotrophs in the soil, and on the photosynthetic efficiency and absorption of zinc in Echinocactus platyacanthus were determined. The soil was characterized physicochemically and placed in experimental pots with E. platyacanthus which were then contaminated with different concentrations of Zn+2. Changes in the rhizospheric bacterial community was analyzed before and after 30 days of contamination with zinc. In this study we found that even when zinc is considered a low toxic metal, their presence in soil selects bacterial groups in the rizosphere involved in stress resistance by heavy metals. Also, at high concentrations it can have negative effects on the rhizospheric community of E. platyacanthus, which could generate serious disturbances in the ecosystem reflected in the loss of bacterial groups that participate in essential functions within the biogeochemical cycles, mainly N cycle. That said, the plant E. platyacanthus was not affected negatively, managing to accumulate a large concentration of metal in its stem and root and can therefore be considered as a plant with phytoaccumulation potential.

Effect of different zinc concentrations on partially-stabilized cement for vital pulp therapy

We have developed and investigated the partially-stabilized cements (PSC) with Zn for vital pulp therapy due to their short setting time and high cell biocompatibility. However, the effect of PSC with different concentrations of Zn on setting time and biocompatibility remained unknown. Therefore, the purpose of this study was to determine the optimal concentration of Zn to be synthesized with PSC for vital pulp therapy. PSC with different weight percentages of Zn (5%, 7%, 10%) were synthesized to attain 5%Zn-PSC, 7%Zn-PSC, and 10%Zn-PSC. The initial and final setting times were measured using the Gillmore needles method, and the compressive strength tests were conducted using a universal testing machine. The phases of Zn-PSC powders were observed using an X-ray diffractometer (XRD). Human dental pulp stem cells (hDPSCs) were used to evaluate the biocompatibility and cytotoxicity of the materials via Alamar blue and LDH assays. Mineral trioxide aggregate (MTA) was used to be compared with Zn-PSC samples. The initial and final setting times of PSC with different concentrations of Zn were reduced considerably compared to those of MTA. The results also indicated that the initial and final setting times decreased as the weight % of Zn increased. 5%Zn-PSC had the highest compressive strength among all tested materials. 5%Zn-PSC samples also displayed comparatively higher cell biocompatibility than 7% and 10% Zn-PSC samples. However, there was no significant difference between the 5%Zn-PSC and MTA in cell biocompatibility. In addition, the results of the LDH release assay indicated a low level of cytotoxicity among all the test samples. 5%Zn-PSC has a shorter setting time, better mechanical properties, and good biocompatibility and thus it has great potential for vital pulp therapy.

Synthesis and structural, magnetic, thermal and electronic properties of Mn-doped ZnCr2Se4

Polycrystalline compounds of the ZnxMnyCrzSe4 system (x + y + z ≈ 3) crystallizing in a cubic spinel structure were successfully synthesized in the concentration range of x = 0.11 ÷ 0.46 using the ceramic method. The influence of manganese on microstructure, magnetic, thermal and electronic properties was investigated. X-ray studies confirmed that the spinel phase forms throughout the entire range (x = 0.1 ÷ 0.5). The results of magnetic measurements showed that the studied compounds are antiferromagnets with the Néel temperature of TN = 12 ÷ 25 K and the Curie-Weiss temperature increasing from θ = 87 K for x = 0.11 to θ = 110 K for x = 0.46. Below TN, the magnetic field dependence of magnetization shows two peculiarities at critical fields Hc1 (connected with metamagnetic threshold accompanied with transition from a helical to a conical phase) and Hc2 (where the conical magnetic structure transforms into a ferromagnetic phase). The values of Hc1 remain almost constant while the values of Hc2 shift into lower magnetic fields as the Mn content increases. These effects are interpreted in terms of the superexchange integrals for the first two coordination spheres including spin defects and non-stoichiometry. The XPS study is consistent with FPLO calculation and discerned Mn2+ charge states. The effects of different concentrations of Zn, Mn and Cr have been demonstrated by XPS experimental results. DSC/TG analysis indicates that the presence of Mn ions in the ZnCr2Se4 crystal lattice affects the stability and resistance of the doped compounds in comparison with the pure ZnCr2Se4.

Protective Effects of Zinc on 2.45GHz Electromagnetic Radiation-Induced Oxidative Stress and Apoptosis in HEK293 Cells.

Several epidemiological studies have shown that exposure to electromagnetic radiation (EMR) can be harmful to human health. The purpose of this study was to examine oxidative parameters and apoptosis induced by EMR in human kidney embryonic cells (HEK293) and to investigate whether zinc (Zn) has protective effect on EMR-induced apoptosis in HEK293 cells. For our experiment, HEK293 cells were divided into four main groups, control, EMR, 50μM Zn + EMR, and 100μM Zn + EMR. HEK293 cells of EMR groups were exposed to 2.45GHz EMR for 1h. In Zn groups, HEK293 cells were incubated with different concentrations of Zn for 48h before EMR exposure. Oxidative stress parameters were determined by spectrophotometric method; bcl-2 and caspase-3 were assessed immunohistochemically and TUNEL method was performed for apoptotic activity. EMR group had higher malondialdehyde (MDA) level and lower superoxide dismutase (SOD) activity compared with control group. In Zn-applied groups, MDA was decreased and SOD activity was increased compared with EMR group. The number of the apoptotic cells and caspase-3 immunopositive cells at EMR group was increased significantly compared with the control group, whereas bcl-2 was decreased. Besides, Zn-treated groups showed a significant reduction in the number of apoptotic cells and caspase-3 from that of EMR group, whereas there was an increase in bcl-2 immunopositivity. Our findings show that EMR caused oxidative stress and apoptotic activation in HEK293 cells. Zn seems to have protective effects on the EMR by increasing SOD activity and bcl-2 immunopositivity, decreasing lipid peroxidation and caspas-3 immunopositivity.

Accumulation potential of Atriplex halimus to zinc and lead combined with NaCl: Effects on physiological parameters and antioxidant enzymes activities

An experiment in this study was designed to investigate the effect of different concentrations of Zn2+ or Pb2+ (0, 200, 400 and 600 μM) with NaCl (0, 200 mM), on the morphological and physiological parameters as well as the antioxidative response of the halophytic species Atriplex halimus. Results showed that Pb2+ had no significant impact on biomass production while Zn2+ significantly affected plant development mainly at high concentration, 600 μM. Total chlorophyll content did not change significantly under elevation concentrations of Zn2+ when compared to control. However, there was a modest decrease in total chlorophyll concentration in the leaves of A. halimus grown in a medium supplemented with 600 μM Pb2+ and with combined stress Pb2+/NaCl. Zn2+ and Pb2+ contents in tissues were higher in the belowground organs of this halophyte. Overall results pointed out that application of different concentrations of Zn2+ or Pb2+ disturbed status of nutrients in A. halimus. Analysis of antioxidant enzymes [ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and catalase (CAT)] showed that the activity was diminished by increasing Zn2+ concentrations in the medium. Whereas, the addition of Pb2+ in the medium increased CAT activity and decreased APX activity.

Signaling pathways involved in human sperm hyperactivated motility stimulated by Zn2+

To fertilize the egg, sperm cells must reside in the female reproductive tract for several hours during which they undergo chemical and motility changes collectively called capacitation. During capacitation, the sperm develop a unique type of motility known as hyperactivated motility (HAM). The semen contains Zn2+ in millimolar concentrations, whereas in the female reproductive tract the concentration is around 1 µM. In this study, we characterize the role of Zn 2+ in human sperm capacitation focusing on its effect on HAM. Western blot analysis revealed the presence of G protein-coupled receptor 39 (GPR39) type Zn-receptor localized mainly in the sperm tail. Zn 2+ at micromolar concentration stimulates HAM, which is mediated by a cascade involving GPR39-AC-cAMP-PKA-Src-EGFR and phospholipase C. Both the transmembrane adenylyl cyclase (AC) and the soluble-AC are involved in the stimulation of HAM by Zn 2+ . The development of HAM is precisely regulated by cyclic adenosine monophosphate, in which relatively low concentration (5-10 µM) stimulated HAM, whereas at 30 µM no stimulation occurred. A similar response was seen when different concentrations of Zn 2+ were added to the cells; low Zn 2+ stimulated HAM, whereas at relatively high Zn 2+ , no effect was seen. We further demonstrate that the Ca 2+ -channel CatSper involved in Zn 2+ -stimulated HAM. These data support a role for extracellular Zn 2+ acting via GPR39 to regulate signaling pathways in sperm capacitation, leading to HAM induction.

Zinc promotes prostate cancer cell chemosensitivity to paclitaxel by inhibiting epithelial-mesenchymal transition and inducing apoptosis.

Paclitaxel (PTX) is a first-line chemotherapeutic drug for the treatment of prostate cancer. However, most patients develop resistance and metastasis, and thus new therapeutic approaches are urgently required. Recent studies have identified widespread anti-tumor effects of zinc (Zn) in various tumor cell lines, especially prostate cancer cells. In this study, we examined the effects of Zn as an adjuvant to PTX in prostate cancer cells. PC3 and DU145 cells were treated with different concentrations of Zn and/or PTX. MTT assay was used to detect cell viability. Real-time cell analysis (RTCA) and microscopy were used to observe morphological changes in cells. Western blotting was used to detect the expression of epithelial-mesenchymal transition (EMT)-related proteins. qPCR (reverse transcription-polymerase chain reaction) was used to examine changes in TWIST1 mRNA levels. Cell invasion and migration were detected by scratch and transwell assays. shRNA against TWIST1 was used to knockdown TWIST1. Colony formation assay was used to detect cell proliferation, while Annexin V and propidium iodide (PI) staining was used to detect cell apoptosis. Zn and PTX increased proliferation inhibition in a dose- and time-dependent manner in prostate cancer cells, while Zn increased prostate cancer cell chemosensitivity to PTX. Combined Zn and PTX inhibited prostate cancer cell invasion and migration by downregulating the expression of TWIST1. Furthermore, knockdown of TWIST1 increased the sensitivity of prostate cancer cells to PTX. In addition, Zn and PTX reduced cell proliferation and induced apoptosis in prostate cancer cells. Our results demonstrated that Zn and PTX combined therapy inhibits EMT by reducing the expression of TWIST1, which reduces the invasion and migration of prostate cancer cells. SiTWIST1 increased the sensitivity of prostate cancer cells to PTX. In addition, with prolonged treatment, Zn and PTX inhibited proliferation and led to prostate cancer cell apoptosis. Therefore, Zn may be a potential adjuvant of PTX in treating prostate cancer and combined treatment may offer a promising therapeutic strategy for prostate cancer.

Luminescent properties of Zn2+-doped CaAl12O19:Mn4+ deep-red phosphor for indoor plant cultivation

A series of CaAl12O19: 0.5%Mn4+ phosphors doped with different concentrations of Zn2+ were prepared via solid state reaction process. The micrographs and phases of powders were analyzed by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively. The Photoluminescence excitation spectra(PLE) and emission spectra(PL) of CaAl12O19: 0.5%Mn4+ with varying Zn2+ concentrations were investigated, the result indicated that prepared samples after Zn2+-doping exhibited deep red emission (658 nm) under the excitation of ultraviolet (UV), near ultraviolet (NUV). PL spectra indicated that Zn2+-doping could remarkably enhance the luminescent intensity of CaAl12O19:0.5%Mn4+. When the doping concentration of Zn2+ was 4%, the emission intensity of Ca0.96Zn0.04Al12O19:0.5%Mn4+ was improved up to 2.2 times that of pure CaAl12O19:0.5%Mn4+. In addition, the emission band of phosphor is highly compatible with the absorption band of phytochrome PR(660 nm). Besides, the internal quantum efficiency (IQE) was up to 67.1%. All the obtained results indicated that CaAl12O19:Zn2+, 0.5%Mn4+ has potential application value in indoor plant cultivation.

Valve teratologies and Chl c in the freshwater diatom Tabellaria flocculosa as biomarkers for metal contamination

Freshwater benthic diatoms, routinely used for bioassessment, are potential metal indicators because of their known capacity to reflect changes in water chemistry. Nevertheless, the effect of metals on benthic freshwater diatoms is still poorly understood. Metals, such as Zn and Cu, are not only essential as micronutrients, but also one of the main anthropogenic pressures in aquatic ecosystems. However, metal stress cannot be detected with the current European standard methods using bioindicators for environmental assessment, so new tools need to be developed. We studied the effects of Zn and Cu on the freshwater diatom Tabellaria flocculosa. This diatom isolated from a Zn and Cu contaminated stream, was exposed to different concentrations of Zn and Cu, and the metal effects were assessed by measuring physiological ((growth, fluorescence, pigments’ content (Chl a, c, carotenoids)) and morphological parameters (teratological forms). We found that at environmental concentrations occurring in European streams, Zn and Cu showed toxic effects on T. flocculosa. Toxic effects induced by Zn were only observed at high concentrations (500 and 1000 µg/L), resulting in fluorescence changes, an increase of Chl c cellular content and an increase of teratological forms (with an increase of more heavily deformed valves with increasing metal concentrations). Increasing Cu exposure induced several changes, such as increasing the cellular content of Chl a and c, while carotenoids’ cellular content decreased. Cu also increased the number of T. flocculosa frustule deformations. Cu did not affect the cellular fluorescence. Our results thus show that the frequency of diatom teratologies could potentially be used to assess metal stress for the studied metals Zn and Cu. Additionally, the analysis of algal pigments could potentially separate the effects of different metals.

Zinc Influences Regeneration of Talinum portulacifolium Stem Cuttings in Nutrient Solution

Zinc (Zn) is an essential micronutrient for plant growth and development, but toxic at high concentrations. The present study focused to underline the direct effect of different concentrations (0-50 ppm) of Zn on the regeneration ability and morphological characteristics of Talinum portulacifolium stem cuttings in hydroponic solution over a period of 35 days without the interference of other soil factors. High concentrations of Zn (40-50 ppm) affected callusing, root initiation, root and shoot development to varying levels. At high concentrations, Zn caused stem decay, stunting and browning of roots, wilting, withering and necrotic spots on leaves. Increasing concentrations of Zn inversely affected the lateral shoot development, stem elongation, leaf, root numbers and total root length of the stem cuttings. Though Zn had no significant influence on fresh or dry weights of stem, low concentration (15 ppm) of Zn increased the fresh and dry weights of leaves by 11.17% and 26.79% respectively, compared to 0 ppm and with 77.06-243.80% and 47.92-255.00% compared with those raised in 20-50 ppm. Zn concentrations >10 ppm reduced the root fresh weight by 28.57-90.47% and dry weight by 27.27-90.91% than those at 0 ppm. The Zn content in leaves and stems increased linearly with increasing concentrations of Zn and ranged from 1.09-125.62 ppm and 1.00-110.26 in stems and leaves respectively. The tolerance index varied between 81 and 138 for different concentrations of Zn. The results of the study clearly indicate that high concentrations of Zn inhibit the regeneration of T. portulacifolium stem cuttings.

Cupriavidus necator strains: zinc and cadmium tolerance and bioaccumulation

ABSTRACT: Among soil microorganisms, the genus Cupriavidus has garnered particular scientific, economic and ecological interest because of its ability to fix nitrogen and tolerate high concentrations of metals. The aim of this study was to analyze four strains of Cupriavidus necator for their ability to tolerate and bioaccumulate cadmium and zinc. The tolerance of these strains to these metals was assessed in liquid culture medium containing different concentrations of Zn + Cd and in soil solutions and soils contaminated with multiple elements including Zn, Cd, Cu and Pb. The four strains showed high tolerance to Zn and Cd, both in culture medium and when inoculated into contaminated soil solutions or multi-element contaminated soil. The UFLA02-71 strain displayed the highest ability to bioaccumulate these metals. It was able to accumulate 93.76 µmol g cell−1 of Zn and 16.03 µmol g cell−1 of Cd when cultured in liquid medium with a total heavy metal concentration of 9,140 µmol L−1 (9,000 Zn + 140 Cd) and was able to accumulate 16.98 µmol g cell−1 of Cd in the soil solution. An increase in the pH of the culture medium resulting from the growth of the C. necator strains reduced the Zn2+ and Cd2+ ions in the medium and increased the concentrations of the ZnHPO4 and CdHPO4 species in solution. Thus, we concluded that they show great potential for use in the bioremediation of HM-contaminated areas.

Zinc Ions Affect Siderophore Production by Fungi Isolated from the Panax ginseng Rhizosphere.

Although siderophore compounds are mainly biosynthesized as a response to iron deficiency in the environment, they also bind with other metals. A few studies have been conducted on the impact of heavy metals on the siderophore-mediated iron uptake by microbiome. Here, we investigated siderophore production by a variety of rhizosphere fungi under different concentrations of Zn²⁺ ion. These strains were specifically isolated from the rhizosphere of Panax ginseng (Korean ginseng). The siderophore production of isolated fungi was investigated with chrome azurol S (CAS) assay liquid media amended with different concentrations of Zn²⁺ (50 to 250 μg/ml). The percentage of siderophore units was quantified using the ultra-violet (UV) irradiation method. The results indicated that high concentrations of Zn²⁺ ion increase the production of siderophore in iron-limited cultures. Maximum siderophore production by the fungal strains was detected at Zn²⁺ ion concentration of 150 μg/ml except for Mortierella sp., which had the highest siderophore production at 200 μg/ml. One potent siderophore-producing strain (Penicillium sp. JJHO) was strongly influenced by the presence of Zn²⁺ ions and showed high identity to P. commune (100% using 18S-rRNA sequencing). The purified siderophores of the Penicillium sp. JJHO strain were chemically identified using UV, Fourier-transform infrared spectroscopy (FTIR), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS) spectra.

Alleviation of Zn Toxicity in Germinated Wheat Grains ( Triticum aestivum L.) By Seed Priming with Defensine Like Protein

THE AIM of this study is to examine the effect of priming the wheat grains with definsine like protein in a trial to enhance their tolerance of Zn toxicity. The present technique was performed on two groups of wheat grains that were germinated under different concentrations of Zn. The first group included the non-primed grains and the second group included the primed grains with definsine like proteins which was extracted and purified from fenugreek seeds. Growth and somephysiological parameters of wheat seedlings were determined. Data revealed that increasing Zn concentrations in the non-primed grains reduced the growth parameters represented by germination ratio and length of both radicle and coleoptile. Also, hydrolysis processes represented by amylase, acid and alkaline phosphatase were significantly decreased, such decrease was accompanied with a decrease in soluble carbohydrates and phosphorus content. Additionally, there was a significant inhibition in the activity of the antioxidant enzymes such as superoxide dismutase, polyphenol oxidase and peroxidase. In contrast, there was an enhancement in the growth process in the definsine primed grains treated with high Zn concentrations. This was associated with a reduction in the oxidative markers such as malondialdehyde (MDA) and H2O2 content. Compared with non-primed grains, an improvement in the activity of the antioxidant enzymes and controlling the excess of the ROS were recorded but no significant effect on the hydrolyzing enzymes was found.

Zn2+-triggered self-assembly of Gonadorelin [6-D-Phe] to produce nanostructures and fibrils

A synthetic derivative, GnRH [6-D-Phe], stable against enzymatic degradation, self-assembles and forms nanostructures and fibrils upon a pH shift in the presence of different concentrations of Zn2+in vitro. Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR–FTIR) revealed the existence of higher order assembly of Zn2+: GnRH [6-D-Phe]. Nuclear Magnetic Resonance spectroscopy (NMR) indicated a weak interaction between Zn2+ and GnRH [6-D-Phe]. Atomic Force Microscopy (AFM) showed the existence of GnRH [6-D-Phe] oligomers and fibrils. Molecular Dynamic (MD) simulation of the 10:1 Zn2+: GnRH [6-D-Phe] explored the interaction and dimerization processes. In contrast to already existing short peptide fibrils, GnRH [6-D-Phe] nanostructures and fibrils form in a Tris-buffered pH environment in a controlled manner through a temperature reduction and a pH shift. The lyophilized Zn2+: GnRH [6-D-Phe] assembly was tested as a platform for the sustained delivery of GnRH [6-D-Phe] and incorporated into two different oil vehicle matrices. The in vitro release was slow and continuous over 14 days and not influenced by the oil matrix.