Excess Zn2 Research Articles

Fluorescent protein-based Zn2+ sensors reveal distinct responses of aerobic and anaerobic Escherichia coli cultures to excess Zn2+

Zinc ions are required by all known organisms. Maintaining zinc homeostasis by preventing toxic overload while ensuring sufficient acquisition for cellular functions is crucial for survival and growth of bacteria. Bacteria, however, frequently encounter and must survive in various environments. During infection in host animals, for example, bacteria are exposed to acidic conditions in the stomach and anaerobic conditions in the intestines, but the effects of oxygen on zinc homeostasis in E. coli have not been well-studied. Previously, we reported a flavin-binding fluorescent protein-based zinc sensor, CreiLOVN41C, which can respond to changes in labile Zn2+ levels in bacteria under both aerobic and anaerobic conditions. Here, we combined the use of CreiLOVN41C with established oxygen-dependent fluorescent protein-based sensors, inductively coupled plasma-mass spectrometry (ICP-MS), and growth curves to evaluate how oxygen levels affect zinc uptake in E. coli. ICP-MS results showed that cells grown aerobically with added zinc acquired more zinc, but no additional zinc was accumulated when cells were grown anaerobically. Using oxygen-independent CreiLOVN41C and the oxygen-dependent ZapCY series of sensors, intracellular labile zinc was detected in E. coli grown with varied zinc under varied conditions. Although little to no endogenous zinc was detected by any sensor in E. coli cells grown with up to 2 mM added zinc, CreiLOVN41C revealed that when Zn2+ was added and detected by cells in real-time, anaerobic cells required more Zn2+ to similarly saturate the sensor. Overall, this work reveals that zinc uptake in E. coli is impacted by oxygen levels during cell growth.

Insight into brain metallothioneins from bidirectional Zn2+ signaling in synaptic dynamics.

The basal levels as the labile Zn2+ pools in the extracellular and intracellular compartments are in the range of ∼10nM and ∼100 pM, respectively. The influx of extracellular Zn2+ is used for memory via cognitive activity and is regulated for synaptic plasticity, a cellular mechanism of memory. When Zn2+ influx into neurons excessively occurs, however, it becomes a critical trigger for cognitive decline and neurodegeneration, resulting in acute and chronic pathogenesis. Aging, a biological process, generally accelerates vulnerability to neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). The basal level of extracellular Zn2+ is age relatedly increased in the rat hippocampus, and the influx of extracellular Zn2+ contributes to accelerating vulnerability to the AD and PD pathogenesis in experimental animals with aging. Metallothioneins (MTs) are Zn2+-binding proteins for cellular Zn2+ homeostasis and involved in not only supplying functional Zn2+ required for cognitive activity, but also capturing excess (toxic) Zn2+ involved in cognitive decline and neurodegeneration. Therefore, it is estimated that regulation of MT synthesis is involved in both neuronal activity and neuroprotection. The present report provides recent knowledge regarding the protective/preventive potential of MT synthesis against not only normal aging but also the AD and PD pathogenesis in experimental animals, focused on MT function in bidirectional Zn2+ signaling in synaptic dynamics.

Noninvasive Diagnosis of Kidney Dysfunction Using a Small-Molecule Manganese-Based Magnetic Resonance Imaging Probe.

Contrast-enhanced magnetic resonance imaging (CE-MRI) is a promising approach for the diagnosis of kidney diseases. However, safety concerns, including nephrogenic systemic fibrosis, limit the administration of gadolinium (Gd)-based contrast agents (GBCAs) in patients who suffer from renal impairment. Meanwhile, nanomaterials meet biosafety concerns because of their long-term retention in the body. Herein, we propose a small-molecule manganese-based imaging probe Mn-PhDTA as an alternative to GBCAs to assess renal insufficiency for the first time. Mn-PhDTA was synthesized via a simple three-step reaction with a total yield of up to 33.6%, and a gram-scale synthesis can be realized. Mn-PhDTA has an r1 relaxivity of 2.72 mM-1 s-1 at 3.0 T and superior kinetic inertness over Gd-DTPA and Mn-EDTA with a dissociation time of 60 min in the presence of excess Zn2+. In vivo and in vitro experiments demonstrate their good stability and biocompatibility. In the unilateral ureteral obstruction rats, Mn-PhDTA provided significant MR signal enhancement, enabled distinguishing structure changes between the normal and damaged kidneys, and evaluated the renal function at different injured stages. Mn-PhDTA could act as a potential MRI contrast agent candidate for the replacement of GBCAs in the early detection of kidney dysfunction and analysis of kidney disease progression.

Cadmium and Zn hyperaccumulation provide efficient constitutive defense against Turnip yellow mosaic virus infection in Noccaea caerulescens

To understand the role of Zn and Cd in anti-viral defence, Zn/Cd hyperaccumulator Noccaea caerulescens plants grown with deficient (0.3 µM), replete (10 µM) and excess (100 µM) Zn2+ and Cd (10 µM Zn2+ + 1 µM Cd2+) were infected with Turnip yellow mosaic virus (TYMV). Gas exchange and chlorophyll fluorescence kinetics analyses demonstrated direct TYMV effects on photosynthetic light reactions but N. caerulescens was more resistant against TYMV than the previously studied non-hyperaccumulator N. ochroleucum. Virus abundance and photosynthesis inhibition were the lowest in the high Zn and Cd treatments. RNAseq analysis of 10 µM Zn2+ plants revealed TYMV-induced upregulation of Ca transporters, chloroplastic ZTP29 and defence genes, but none of those that are known to be strongly involved in hyperaccumulation. Synchrotron µ-XRF tomography, however, showed that Zn hyperaccumulation remained strongest in vacuoles of epidermal storage cells regardless of infection. This was in contrast to N. ochroleucum, where apoplastic Zn drastically increased in response to TYMV. These results suggest that the antiviral response of N. caerulescens is less induced by the onset of this biotic stress, but it is rather a permanent resistant state of the plant. Real-time qPCR revealed upregulation of ferritin in Zn10 infected plants, suggesting Fe deprivation as a virus defence strategy under suboptimal Zn supply.

Zn2+-interference and H2S-mediated gas therapy based on ZnS-tannic acid nanoparticles synergistic enhancement of cell apoptosis for specific treatment of prostate cancer

Zn2+ and H2S are essential to maintain normal prostate function, and sometimes can evolve into weapons to attack and destroy prostate cancer (PCa) cells. Nevertheless, how to achieve the targeted and effective release of Zn2+ and H2S, and reverse the concentration distribution within PCa tumor cells still highly challenging. Herein, combined with these pathological characteristics of prostate, we proposed a tumor microenvironment (TME) responsive Zn2+-interference and H2S-mediated gas synergistic therapy strategy based on a nanoplatform of tannic acid (TA) modified zinc sulfide nanoparticles (ZnS@TA) for the specific treatment of PCa. Once the constructed pH-responsive ZnS@TA internalized by cancer cells, it would instantaneously decomposed in acidic TME, and explosively release excess Zn2+ and H2S exceeding the cell self-regulation threshold. Meanwhile, the in situ produced Zn2+ and H2S synergistic enhancement of cell apoptosis, which is evidenced to increase levels of Bax and Bax/Bcl-2 ratio, release of Cytochrome c in cancer cells, contributing to inhibit the growth of tumor. Moreover, the TA in cooperation with Zn2+ specifically limits the migration and invasion of PCa cells. Both in vitro and in vivo results demonstrate that the Zn2+-interference in combination with H2S-mediated gas therapy achieves an excellent anti-tumor performance. Overall, this nanotheranostic synergistic therapy provides a promising direction for exploring new strategies for cancer treatment based on specific tumor pathological characteristics, and provides a new vision for promoting practical cancer therapy.

Psoralen synergies with zinc implants to promote bone repair by regulating ZIP4 in rats with bone defect

BackgroundThe regulation of dose-dependent biological effects induced by biodegradation is a challenge for the production of biodegradable bone-substitute materials, especially biodegradable zinc (Zn) -based materials. Cytotoxicity caused by excess local Zn ions (Zn2+) from degradation is one of the factors limiting the wide application of Zn implants. Given that previous studies have revealed that delayed degradation of Zn materials by surface modification does not reduce cytotoxicity; in the present study, we explore whether preventing the entry of excess Zn2+ into cells may can reduce local Zn toxicity by applying Psoralen (PRL) to Zn implants and assessing its ability to regulate intracellular Zn2+ concentrations.MethodsThe effects of different concentrations of Zn2+ on cellular activity and cytotoxicity were investigated; briefly, we identified natural compounds that regulate Zn transporters, thereby regulating the concentrations of intracellular Zn2+, and applied them to Zn materials. Of these materials, PRL, a natural, tricyclic, coumarin-like aromatic compound that promotes the proliferation and differentiation of osteoblasts and enhances osteogenic activity, was loaded onto the surface of a Zn material using peptides and chitosan (CS), and the surface characteristics, electrochemical properties, and activity of the modified Zn material were evaluated. In addition, the ability of Zn + CS/pPRL implants to promote bone formation and accelerate large-scale bone defect repairs was assessed both in vitro and in vivo.ResultsWe determined that 180 µM Zn2+ significantly induced pre-osteoblast cytotoxicity, and a 23-fold increase in Zrt- and Irt-like protein 4 (ZIP4) expression. We also found that PRL dynamically regulates the expression of ZIP4 in response to Zn2+ concentration. To address the problem of cytotoxicity caused by excessive Zn2+ in local Zn implants, PRL was loaded onto the surface of Zn implants in vivo using peptides and CS, which dynamically regulated ZIP4 levels, maintained the balance of intracellular Zn2+ concentrations, and enhanced the osteogenic activity of Zn implants.ConclusionsThis study reveals the importance of Zn2+ concentration when using Zn materials to promote bone formation and introduces a natural active ingredient, PRL, that can regulate intracellular Zn2+ levels, and thus may be clinically applicable to Zn implants for the treatment of critical bone defects.Graphical

“Block and attack” strategy for tumor therapy through ZnO2/siRNA/NIR‐mediating Zn2+‐overload and amplified oxidative stress

AbstractIntracellular zinc ion (Zn2+) accumulation disrupts the Zn2+ homeostasis, providing an ion‐overloading anticancer strategy with great potential. The self‐adaptation of tumor cells to ion concentration, however, puts forward higher requirements for the design of ion‐overloading strategy. Herein, “block and attack” antitumor strategy was applied through a composite nanomaterials (UHSsPZH NPs). The strategy demonstrated powerful ion interference ability through both “blocking” the efflux of excess Zn2+ via gene silencing and “attacking” tumor cells via target delivery of ZnO2. After cellular internalization, ZnO2 was degraded to Zn2+ and hydrogen peroxide (H2O2), and the gene expression of zinc transporter 1 (ZnT1) was silenced by targeting of released siRNA, which together caused intracellular Zn2+‐overload. Disorder of Zn2+ further interfered with intracellular Ca2+ homeostasis, inhibited the electron transport chain and promoted the production of endogenous reactive oxygen species (ROS), which assisted the “attack” to tumor cells together with the exogenous ROS generated by UHSsPZH NPs under 980 nm laser irradiation. In summary, this work supplies a “block and attack” strategy for the application of ion homeostasis interference in tumor therapy.

Fluorescence turn‐off and turn‐on sensors of Zn2+ based on π‐conjugated poly(aryleneethynylene)s comprising alloxazine‐6,9‐diyl and 2,7‐diethynylene‐9,9‐dialkylfluorene units

Abstractπ‐Conjugated poly(aryleneethynylene)s, polymer‐1 comprising alloxazine‐6,9‐diyl and 2,7‐diethynylene‐9,9‐dihexylfluorene units and polymer‐2 comprising alloxazine‐6,9‐diyl and 2,7‐diethynylene‐9,9‐bis(hexaethylene glycol monomethyl ether)fluorene units, were synthesized via Pd‐complex‐catalyzed condensation reactions. The Mn values of polymers 1 and 2 were 5200 and 8100, and Mw values were 24,900 and 69,700, respectively. The onset wavelengths of the polymers were longer wavelength than that of the monomer in the UV–vis spectra, confirming the π‐conjugated system along the polymer chain. The photoluminescence (PL) of the polymers decreased with the addition of Zn2+ until an equimolar amount and then increased upon the addition of an excess amount of Zn2+, which enabled the detection of Zn2+ over a wider concentration range (10−6–10−4 M) than those of the previously reported Zn2+ sensors. The PL intensity upon the addition of excess Zn2+ was greater in polymer‐2 than in polymer‐1 because the Zn2+‐alloxazine complex in polymer‐2 was stabilized by its interaction with the oligoether side chain. The difference in the PL response of the polymers to metal ions such as Cu+, Cu2+, and Zn2+ was analyzed using the Stern–Volmer and Benesi–Hildebrand methods.

Effect of Zn2+ on emodin molecules studied by time-resolved fluorescence spectroscopy and quantum chemical calculations

Emodin is a natural drug for treating neurodegenerative diseases and plays a vital role in the mitigation of nerve damage. Metal ions can modify the drug properties of emodin, where Zn2+ can synergize with the emodin molecule and enhance the drug effect of emodin. Besides, complex changes can be observed in the fluorescence intensity and fluorescence lifetime of the emodin molecule as the concentration of Zn2+ increases. Herein, the synergistic effects of ligand structural in Zn(II)-Emodin complexes and the electronic effects of metal elements on the antioxidant properties of the complexes are discussed in detail based on UV–vis absorption spectroscopy, fluorescence spectroscopy, time-correlated single photon counting (TCSPC) technique and quantum chemical calculations at the B3LYP/6-31G(d) level. The experimental results confirm that Zn2+ can coordinate with the hydroxyl groups on the emodin to make the molecule structure more rigid, thus inhibiting the non-radiative processes such as high-frequency vibrations of the emodin molecule in solution. The suppression of non-radiative processes leads to an increase in the average fluorescence lifetime of the emodin molecule, and finally results in the enhanced fluorescence intensity. The chemical softness of Zn(II)-Emodin is then confirmed to be higher than that of emodin by Gaussian calculations, indicating its higher chemical reactivity and lower stability. The stronger electron donating ability of Zn(II)-Emodin compared to emodin may explain the higher antioxidant activity of Zn(II)-Emodin, which gives it a stronger pharmacological activity. The results of this study show that emodin can well complex with Zn2+ to remove excess Zn2+ in human body and the resulting complex has better antioxidant properties, which helps to understand the role of Zn2+ in drug-metal coordination and provides guidance for the design of new drugs.

Zn0.52V2O5−a⋅1.8 H2O Cathode Stabilized by In Situ Phase Transformation for Aqueous Zinc‐Ion Batteries with Ultra‐Long Cyclability

AbstractDeveloping cathode materials integrating good rate performance and sufficient cycle life is the key to commercialization of aqueous zinc‐ion batteries. The hyperstable Zn0.52V2O5−a⋅1.8 H2O (ZVOH) cathode with excellent rate performance has been successfully developed via an in situ self‐transformation from zinc‐rich Zn3V3O8 (ZVO) in this study. Different from the common synthetic method of additional Zn2+ pre‐insertion, ZVOH is obtained from the insertion of structural H2O and the removal of excess Zn2+ in ZVO, ensuring the lattice structure of ZVOH remains relatively intact during the phase transition and rendering good structural stabilities. The ZVOH delivers a reversible capacity of 286.2 mAh g−1 at 0.2 A g−1 and of 161.5 mAh g−1 at 20 A g−1 over 18 000 cycles with a retention of 95.4 %, demonstrating excellent rate performance and cyclic stability. We also provide new insights on the structural self‐optimization of Znx(CF3SO3)y(OH)2x−y⋅n H2O byproducts and the effect on the mobility of Zn2+ by theoretical calculations and experimental evidence.

Zn0.52 V2 O5-a ⋅1.8 H2 O Cathode Stabilized by In Situ Phase Transformation for Aqueous Zinc-Ion Batteries with Ultra-Long Cyclability.

Developing cathode materials integrating good rate performance and sufficient cycle life is the key to commercialization of aqueous zinc-ion batteries. The hyperstable Zn0.52 V2 O5-a ⋅1.8 H2 O (ZVOH) cathode with excellent rate performance has been successfully developed via an in situ self-transformation from zinc-rich Zn3 V3 O8 (ZVO) in this study. Different from the common synthetic method of additional Zn2+ pre-insertion, ZVOH is obtained from the insertion of structural H2 O and the removal of excess Zn2+ in ZVO, ensuring the lattice structure of ZVOH remains relatively intact during the phase transition and rendering good structural stabilities. The ZVOH delivers a reversible capacity of 286.2 mAh g-1 at 0.2 A g-1 and of 161.5 mAh g-1 at 20 A g-1 over 18 000 cycles with a retention of 95.4 %, demonstrating excellent rate performance and cyclic stability. We also provide new insights on the structural self-optimization of Znx (CF3 SO3 )y (OH)2x-y ⋅n H2 O byproducts and the effect on the mobility of Zn2+ by theoretical calculations and experimental evidence.

Reversible and biocompatible AuNP-decorated [Zn2+]:[Insulin] condensed assembly for potential therapeutic applications

The present study reports the construction of Gold Nanoparticle (AuNP)-decorated [Zn2+]:[Insulin] condensed assembly which was found to be reversible and biocompatible. At first, Citrate-Capped AuNPs were synthesized using the Turkevich method, and the colloidal solution was co-incubated with [Zn2+]:[Insulin] maintaining an equimolar stoichiometry, at physiological pH, 60 °C and 6 h. Accordingly, the effect of excess Zn2+ and surface sorption events were investigated. The surface chemistry of protein sorption on AuNPs involved interaction of surface citrate with the amyloidogenic residues of insulin Chain A (L13, E17, N18) and Chain B (V12, Y16, L17), and also C7:A, C7:B, C20:A. The surface sorption involved a number of driving forces which were predicted to be covalent, H-bonding and hydrophobic interactions. Upon the capture of a fraction of insulin molecules, the Zn2+ was found to form cross-links between the unbound monomers and insulin bound on AuNP, thus forming nucleating species with dendritic morphology. The dendritic species self-assembled into linear and branched organization, followed by the formation of densely packed AuNP-decorated [Zn2+]:[Insulin] condensed assembly. Subsequently, alteration of pH resulted in changes of local charges, thus destabilizing the intermolecular ionic interactions, and subsequently caused the reversal of the condensed assembly back to monomeric forms. Furthermore, the reversible AuNP-decorated [Zn2+]:[Insulin] condensate was found to be biocompatible, and promoted the growth of the adherent cell line, BHK-21 fibroblasts. The non-cytotoxic and reversible material thus formed might have enormous applications in bioelectronics, cell culture matrices, and drug-delivery systems.

Excess Zinc Supply Reduces Cadmium Uptake and Mitigates Cadmium Toxicity Effects on Chloroplast Structure, Oxidative Stress, and Photosystem II Photochemical Efficiency in Salvia sclarea Plants.

Salvia sclarea L. is a Cd2+ tolerant medicinal herb with antifungal and antimicrobial properties cultivated for its pharmacological properties. However, accumulation of high Cd2+ content in its tissues increases the adverse health effects of Cd2+ in humans. Therefore, there is a serious demand to lower human Cd2+ intake. The purpose of our study was to evaluate the mitigative role of excess Zn2+ supply to Cd2+ uptake/translocation and toxicity in clary sage. Salvia plants were treated with excess Cd2+ (100 μM CdSO4) alone, and in combination with Zn2+ (900 μM ZnSO4), in modified Hoagland nutrient solution. The results demonstrate that S. sclarea plants exposed to Cd2+ toxicity accumulated a significant amount of Cd2+ in their tissues, with higher concentrations in roots than in leaves. Cadmium exposure enhanced total Zn2+ uptake but also decreased its translocation to leaves. The accumulated Cd2+ led to a substantial decrease in photosystem II (PSII) photochemistry and disrupted the chloroplast ultrastructure, which coincided with an increased lipid peroxidation. Zinc application decreased Cd2+ uptake and translocation to leaves, while it mitigated oxidative stress, restoring chloroplast ultrastructure. Excess Zn2+ ameliorated the adverse effects of Cd2+ on PSII photochemistry, increasing the fraction of energy used for photochemistry (ΦPSII) and restoring PSII redox state and maximum PSII efficiency (Fv/Fm), while decreasing excess excitation energy at PSII (EXC). We conclude that excess Zn2+ application eliminated the adverse effects of Cd2+ toxicity, reducing Cd2+ uptake and translocation and restoring chloroplast ultrastructure and PSII photochemical efficiency. Thus, excess Zn2+ application can be used as an important method for low Cd2+-accumulating crops, limiting Cd2+ entry into the food chain.

Manganese(II)-Based Responsive Contrast Agent Detects Glucose-Stimulated Zinc Secretion from the Mouse Pancreas and Prostate by MRI.

A Mn(II)-based zinc-sensitive MRI contrast agent, MnPyC3A-BPEN, was prepared, characterized, and applied in imaging experiments to detect glucose-stimulated zinc secretion (GSZS) from the mouse pancreas and prostate in vivo. Thermodynamic and kinetic stability tests showed that MnPyC3A-BPEN has superior kinetic inertness compared to GdDTPA, is less susceptible to transmetalation in the presence of excess Zn2+ ions, and less susceptible to transchelation by albumin. In comparison with other gadolinium-based zinc sensors bearing a single zinc binding moiety, MnPyC3A-BPEN appears to be a reliable alternative for imaging β-cell function in the pancreas and glucose-stimulated zinc secretion from the prostate.

A novel zinc transporter essential for Arabidopsis zinc and iron-dependent growth

Zinc (Zn), an essential micronutrient, is absorbed by plant roots and redistributed to leaves. This process must be finely regulated in order to avoid toxic Zn2+ overaccumulation, which can arise due to Zn2+ oversupply or Zn2+ hyperaccumulation induced by Fe2+ deficiency. Although several proteins in Arabidopsis thaliana are essential for retaining Zn in the root and partitioning it from roots to leaves, how Zn2+ homeostasis in leaves is maintained is largely unknown. In this study, we identified a novel Golgi-localized protein named ZINC NUTRIENT ESSENTIAL1 (AtZNE1,At3g08650) in Arabidopsis. AtZNE1 contains 14 putative transmembrane domains. AtZNE1 promoter has strong activity in the root and leaf. Its expression complemented the increased sensitivity of a yeast mutant to excess Zn2+. The disruption of AtZNE1 in the T-DNA insertion mutant atzne1 caused growth defect under excess-Zn or Fe deficit conditions, but had no effects on the total Zn and Fe contents. We propose that AtZNE1 plays a vital role in plant adaptation to excess Zn or Fe deficiency.

Atroxlysin-III, A Metalloproteinase from the Venom of the Peruvian Pit Viper Snake Bothrops atrox (Jergón) Induces Glycoprotein VI Shedding and Impairs Platelet Function.

Atroxlysin-III (Atr-III) was purified from the venom of Bothrops atrox. This 56-kDa protein bears N-linked glycoconjugates and is a P-III hemorrhagic metalloproteinase. Its cDNA-deduced amino acid sequence reveals a multidomain structure including a proprotein, a metalloproteinase, a disintegrin-like and a cysteine-rich domain. Its identity with bothropasin and jararhagin from Bothrops jararaca is 97% and 95%, respectively. Its enzymatic activity is metal ion-dependent. The divalent cations, Mg2+ and Ca2+, enhance its activity, whereas excess Zn2+ inhibits it. Chemical modification of the Zn2+-complexing histidine residues within the active site by using diethylpyrocarbonate (DEPC) inactivates it. Atr-III degrades plasma fibronectin, type I-collagen, and mainly the α-chains of fibrinogen and fibrin. The von Willebrand factor (vWF) A1-domain, which harbors the binding site for GPIb, is not hydrolyzed. Platelets interact with collagen via receptors for collagen, glycoprotein VI (GPVI), and α2β1 integrin. Neither the α2β1 integrin nor its collagen-binding A-domain is fragmented by Atr-III. In contrast, Atr-III cleaves glycoprotein VI (GPVI) into a soluble ~55-kDa fragment (sGPVI). Thereby, it inhibits aggregation of platelets which had been stimulated by convulxin, a GPVI agonist. Selectively, Atr-III targets GPVI antagonistically and thus contributes to the antithrombotic effect of envenomation by Bothrops atrox.

Study on the reuse of anaerobic digestion effluent in lactic acid production

Abstract A novel process for reuse of anaerobic digestion effluent in lactic acid fermentation was investigated to resolve wastewater pollution in lactic acid industry. A series of experiments were performed and the results showed that anaerobic digestion effluent directly reused did not affect liquefaction of raw materials, but inhibited lactic acid fermentation instead. Further experimental studies proved that excess ammonia-nitrogen, Zn2+, Fe2+, S and Mn2+ in the anaerobic digestion effluent could inhibit lactic acid fermentation and their corresponding critical inhibition concentrations were 100 mg/L, 1 mg/L,1 mg/L, 2.5 mg/L and 1 mg/L, respectively. In this paper, the activated carbon treatment was adopted to process the anaerobic digestion effluent, and these inhibitors had been effectively removed. The removal rate of metal ions reached 75%, and that for ammonia-nitrogen was over 80%. Application of the treated anaerobic digestion effluent in lactic acid fermentation, there was 129.59 ± 3.13 g/L of lactic acid, which was comparable to the control (130.09 ± 2.12 g/L). This new process is of significance to the realization of no-waste manufacturing, energy saving and emission reduction in lactic acid industry. It can be concluded that a cleaner way to produce lactic acid is realized.

Synthesizing ZnWO4 with enhanced performance in photoelectrocatalytic inactivating marine microorganisms

ZnWO4 was synthesized by a hydrothermal method, and different molar ratios of Zn2+/WO42− were prepared in precursor solution systems (Zn2+:WO42− = 1:1, 2:1, 3:1, 4:1, 1:2, 1:3, 1:4) in the synthesis process. On the whole, the photocatalytic activity increases with excess Zn2+ and decreases when excess WO42− is in the precursor solution; the sample exhibited the best performance when Zn2+:WO42− = 3:1, with inactivation time of 7 min, which is 36% shorter than for the original sample (1:1). The CV tests showed that the OH generation ability strengthened with excess Zn2+ and weakened with abundant WO42−; according to the SEM results, long and uniform nanorods can be gained when Zn2+ is in excess in the precursor solution, and the morphology became bulky in the case of WO42−. Apart from the morphology and properties, the immanent cause is the exposed (100) high energy plane under the Zn2+-rich condition. Generally, the molar ratio of Zn2+/WO42− in the precursor solution could adjust the morphology and face exposure of products and improve the photocatalytic activity of ZnWO4. Simultaneously, photoelectrocatalytic technology can effectively separate the e−/h+ pairs, which greatly enhances the inactivation activity.

Cloning, function, and localization of human, canine, and Drosophila ZIP10 (SLC39A10), a Zn2+ transporter.

Zinc (Zn2+) is the second most abundant trace element, but is considered a micronutrient, as it is a cofactor for many enzymes and transcription factors. Whereas Zn2+ deficiency can cause cognitive immune or metabolic dysfunction and infertility, excess Zn2+ is nephrotoxic. As for other ions and solutes, Zn2+ is moved into and out of cells by specific membrane transporters: ZnT, Zip, and NRAMP/DMT proteins. ZIP10 is reported to be localized at the apical membrane of renal proximal tubules in rats, where it is believed to play a role in Zn2+ import. Renal regulation of Zn2+ is of particular interest in light of growing evidence that Zn2+ may play a role in kidney stone formation. The objective of this study was to show that ZIP10 homologs transport Zn2+, as well as ZIP10, kidney localization across species. We cloned ZIP10 from dog, human, and Drosophila ( CG10006), tested clones for Zn2+ uptake in Xenopus oocytes and localized the protein in renal structures. CG10006, rather than foi (fear-of-intimacy, CG6817) is the primary ZIP10 homolog found in Drosophila Malpighian tubules. The ZIP10 antibody recognizes recombinant dog, human, and Drosophila ZIP10 proteins. Immunohistochemistry reveals that ZIP10 in higher mammals is found not only in the proximal tubule, but also in the collecting duct system. These ZIP10 proteins show Zn2+ transport. Together, these studies reveal ZIP10 kidney localization, a role in renal Zn2+ transport, and indicates that CG10006 is a Drosophila homolog of ZIP10.

Triticum urartu MTP1: its ability to maintain Zn2+ and Co2+ homeostasis and metal selectivity determinants.

TuMTP1 maintains Zn2+ and Co2+ homeostasis by sequestering excess Zn2+ and Co2+ into vacuoles. The mutations NSEDD/VTVTT in the His-rich loop and I119F in TMD3 of TuMTP1 restrict metal selectivity. Mineral nutrients, such as zinc (Zn) and cobalt (Co), are essential or beneficial for plants but can be toxic at elevated levels. Metal tolerance proteins (MTPs) are plant members of the cation diffusion facilitator (CDF) transporter family involved in cellular metal homeostasis. However, the determinants of substrate selectivity have not been clarified due to the diversity of MTP1 substrates in various plants. In this study, Triticum urartu MTP1 was characterized. When expressed in yeast, TuMTP1 conferred tolerance to Zn2+ and Co2+ but not Fe2+, Cu2+, Ni2+ or Cd2+ in solid and liquid culture and localized on the vacuolar membrane. Furthermore, TuMTP1-expressing yeast accumulated more Zn2+ and Co2+ when treated. TuMTP1 expression in T. urartu roots was significantly increased under Zn2+ and Co2+ stresses. Determinants of substrate selectivity were then examined through site-directed mutagenesis. The exchange of NSEDD with VTVTT in the His-rich loop of TuMTP1 restricted its metal selectivity to Zn2+, whereas the I119F mutation confined specificity to Co2+. The mutations H74, D78, H268 and D272 (in the Zn2+-binding site) and Leu322 (in the C-terminal Leu-zipper) partially or completely abolished the transport function of TuMTP1. These results show that TuMTP1 might sequester excess cytosolic Zn2+ and Co2+ into yeast vacuoles to maintain Zn2+ and Co2+ homeostasis. The NSEDD/VTVTT and I119F mutations are crucially important for restricting the substrate specificity of TuMTP1, and the Zn2+-binding site and Leu322 are essential for its ion selectivity and transport function. These results can be employed to change metal selectivity for biofortification or phytoremediation applications.