Zinc shields against copper phytotoxicity in a contaminated soil.

While zinc protects plants from copper in hydroponics, its behavior in soil remains unclear. We investigated the potential of zinc sulfate to protect ryegrass from copper toxicity in contaminated soil. Twelve soil treatments combined varying levels of copper oxide (CuO) and zinc sulfate (ZnSO4). Increasing CuO significantly stunted ryegrass, but adding ZnSO4 mitigated the effects at each CuO level. ZnSO4 had no effect in unpolluted conditions. These results, supported by the Terrestrial Biotic Ligand Model, indicate that zinc competes with copper for binding sites, reducing copper uptake by ryegrass and mitigating its toxicity. Application of zinc sulfate to copper-contaminated soils appears promising for ryegrass growth, although field studies are critical to confirm real-world efficacy.

The differential expressions of aquaporins underline the diverse strategies of cucumber and tomato against salinity and zinc stress.

Salinity and excess zinc are two main problems that have limited agriculture in recent years. Aquaporins are crucial in regulating the passage of water and solutes through cells and may be essential for mitigating abiotic stresses. In the present study, the adaptive response to moderate salinity (60 mM NaCl) and excess Zn (1 mM ZnSO4 ) were compared alone and in combination in Cucumis sativus L. and Solanum lycopersicum L. Water relations, gas exchange and the differential expression of all aquaporins were analysed. The results showed that cucumber plants under salinity maintained the internal movement of water through osmotic adjustment and the overexpression of specific PIPs aquaporins, following a "conservation strategy". As tomato has a high tolerance to salinity, the physiological parameters and the expression of most aquaporins remained unchanged. ZnSO4 was shown to be stressful for both plant species. While cucumber upregulated 7 aquaporin isoforms, the expression of aquaporins increased in a generalized manner in tomato. Despite the differences, water relations and transpiration were adjusted in both plants, allowing the RWC in the shoot to be maintained. The aquaporin regulation in cucumber plants facing NaCl+ZnSO4 stress was similar in the two treatments containing NaCl, evidencing the predominance of salt in stress. However, in tomato, the induced expression of specific isoforms to deal with the combined stress differed from independent stresses. The results clarify the key role of aquaporin regulation in facing abiotic stresses and their possible use as markers of tolerance to salinity and heavy metals in plants.

Research Note: Relative bioavailability of zinc in zinc hydroxychloride for chicks.

A chick assay was conducted to determine the effects of Zn source on performance and to establish a Zn relative bioavailability value (RBV) for a new source of Zn hydroxychloride. In the assay, 8-day-old chicks were fed a Zn-deficient soy protein concentrate diet supplemented with 0, 7, and 15 mg Zn/kg from feed grade ZnSO4 monohydrate for 14 d to establish a standard response curve. The same basal diet was supplemented with 3, 7, and 10 mg Zn/kg from a new Zn hydroxychloride (SAMZn). A second source of Zn hydroxychloride (IBZn) was supplemented at 10 mg Zn/kg as a direct comparison to the highest level of SAMZn. Weight gain increased (P < 0.05) with increasing Zn level, regardless of source. Weight gain of chicks fed 7 mg Zn/kg from SAMZn was not different (P > 0.05) from chicks fed 15 mg Zn/kg from ZnSO4. Weight gain was not different (P > 0.05) when comparing the 2 sources of Zn hydroxychloride supplemented at 10 mg Zn/kg. Tibia ash Zn and total tibia Zn were increased (P < 0.05) by all Zn sources and responded linearly (P < 0.05) to Zn supplementation from ZnSO4 and SAMZn. Total tibia Zn concentration was not different (P > 0.05) for chicks fed 10 mg Zn/kg from either source of Zn hydroxychloride. Multiple linear regression of total tibia Zn on supplemental Zn intake (R2 = 0.95) resulted in a RBV of 115% for SAMZn compared with ZnSO4 (set at 100%). The RBV of SAMZn was higher (P < 0.05) than ZnSO4. In conclusion, relative bioavailability of Zn (based on tibia Zn) in Zn hydroxychloride from SAMZn was higher than feed grade ZnSO4 based on multiple regression slope-ratio analysis and was similar to that of IBZn Zn hydroxychloride based on tibia Zn responses to 10 mg/kg supplemental dietary Zn.

Enhancing wheat production and quality in alkaline soil: a study on the effectiveness of foliar and soil applied zinc.

Cultivation of high-yield varieties and unbalanced fertilization have induced micronutrient deficiency in soils worldwide. Zinc (Zn) is an essential nutrient for plant growth and its deficiency is most common in alkaline and calcareous soils. Therefore, this study aimed to evaluate the effect of Zn applied either alone or in combination with foliar application on the quality and production of wheat grown in alkaline soils. Zn was applied in the form of zinc sulfate (ZnSo4) to the soil and as a foliar spray during the sowing and tillering stages, respectively. Results showed that Zn fertilization of wheat, irrespective of modes of application, significantly increased grain and biological yield, grain per spike, and 1,000 grains weight over control; however, its effect was more noticeable when applied as 7.5 kg ha-1 of soil Zn combined with foliar Zn at 2.5 kg ha-1. Zn application significantly increased the grain protein content from 9.40% in the control to a maximum of 11.83% at soil Zn of 10 kg ha-1. Similarly, Zn application improved Zn, phosphorus (P), and potassium (K) concentrations in wheat grains. Moreover, correlation analysis showed that the grain Zn concentration was positively correlated with the grain P concentration. The correlation between P concentration in wheat grains and 1,000 grain weight was not significant. A total of 1,000 grains weight was positively correlated with tillers per plant, grain yield, and biological yield. There were positive correlations between protein content, biological yield, grain yield, and tillers per plant. Therefore, soil-applied Zn + foliar application in alkaline soils with limited Zn availability is crucial for improving wheat yield and grain quality.

Differential response of nano zinc sulphate with other conventional sources of Zn in mitigating salinity stress in rice grown on saline-sodic soil.

Salinization causes the degradation of the soil and threatening the global food security but the application of essential micronutrients like zinc (Zn), improve the plant growth by stabilizing the plant cell and root development. Keeping in view the above-mentioned scenario, an experiment was conducted to compare the efficiency of conventional Zn fertilizers like zinc sulphate (ZnSO4), zinc ethylene diamine tetra acetic acid (Zn-EDTA) and advance nano Zn fertilizers such as zinc sulphate nanoparticles (ZnSO4NPs), and zinc oxide nanoparticles (ZnONPs) (applied at the rate of 5 and 10 mg/kg) in saline-sodic soil. Results revealed that the maximum plant height (67%), spike length (72%), root length (162%), number of tillers (71%), paddy weight (100%), shoot dry weight (158%), and root dry weight (119%) was found in ZnSO4NPs applied at the rate of 10 mg/kg (ZnSO4NPs-10) as compared to salt-affected control (SAC). Similarly, the plants physiological attributes like chlorophyll contents (91%), photosynthesis rate (113%), transpiration rate (106%), stomatal conductance (56%) and internal CO2 (11%) were increased by the application of ZnSO4NPs-10, as compared to SAC. The maximum Zn concentration in root (153%), shoot (205%) and paddy (167%) found in ZnSO4NPs-10, as compared to control. In the body of rice plants, other nutrients like phosphorus and potassium were also increased by the application of ZnSO4NPs-10 and soil chemical attributes such as sodium and sodium adsorption ratio were decreased. The current experiment concluded that the application of ZnSO4NPs at the rate of 10 mg/kg in salt-affected paddy soil increased the growth, physiology, up take of essential nutrients and yield of rice by balancing the cationic ratio under salt stress.

Enrichment of Zinc and Iron Micronutrients in Lentil (Lens culinaris Medik.) through Biofortification.

Biofortification of pulse crops with Zn and Fe is a viable approach to combat their widespread deficiencies in humans. Lentil (Lens culinaris Medik.) is a widely consumed edible crop possessing a high level of Zn and Fe micronutrients. Thus, the present study was conducted to examine the influence of foliar application of Zn and Fe on productivity, concentration, uptake and the economics of lentil cultivation (LL 931). For this, different treatment combinations of ZnSO4·7H2O (0.5%) and FeSO4·7H2O (0.5%), along with the recommended dose of fertilizer (RDF), were applied to the lentil. The results of study reported that the combined foliar application of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at pre-flowering (S1) and pod formation (S2) stages was most effective in enhancing grain and straw yield, Zn and Fe concentration, and uptake. However, the outcome of this treatment was statistically on par with the results obtained under the treatment ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage. A single spray of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage enhanced the grain and straw yield up to 39.6% and 51.8%, respectively. Similarly, Zn and Fe concentrations showed enhancement in grain (10.9% and 20.4%, respectively) and straw (27.5% and 27.6% respectively) of the lentil. The increase in Zn and Fe uptake by grain was 54.8% and 68.0%, respectively, whereas uptake by straw was 93.6% and 93.7%, respectively. Also the benefit:cost was the highest (1.96) with application of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage. Conclusively, the combined use of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage can contribute significantly towards yield, Zn and Fe concentration, as well as uptake and the economic returns of lentil to remediate the Zn and Fe deficiency.

Punicalagin and zinc (II) ions inhibit the activity of SARS-CoV-2 3CL-protease in vitro.

OBJECTIVE: Coronavirus 2019 (COVID-19) has now been declared as a worldwide pandemic. Currently, no drugs have been endorsed for its treatment; in this manner, a pressing need has been developed for any antiviral drugs that will treat COVID-19. Coronaviruses require the SARS-CoV-2 3CL-Protease (3CL-protease) for cleavage of its polyprotein to yield a single useful protein and assume a basic role in the disease progression. In this study, we demonstrated that punicalagin, the fundamental active element of pomegranate in addition to the combination of punicalagin with zinc (Zn) II, appear to show powerful inhibitory activity against SARS-CoV-2. MATERIALS AND METHODS: The 3CL protease assay kit was used to quantify 3CL protease action. The tetrazolium dye, MTS, was used to evaluate cytotoxicity. RESULTS: Punicalagin showed inhibitory action against the 3CL-protease in a dose-dependent manner, and IC50 was found to be 6.192 µg/ml for punicalagin. Punicalagin (10 µg/mL) demonstrated a significant inhibitory activity toward 3CL-protease activity (p < 0.001), yet when punicalagin is combined with zinc sulfate monohydrate (punicalagin/Zn-II) extremely strong 3CL-protease activity (p < 0.001) was obtained. The action of 3CL-protease with punicalagin/Zn-II was decreased by approximately 4.4-fold in contrast to only punicalagin (10 µg/mL). Likewise, we did not notice any significant cytotoxicity caused by punicalagin, Zn-II, or punicalagin/Zn-II. CONCLUSIONS: We suggest that these compounds could be used as potential antiviral drugs against COVID-19.

Zinc Oxide Nanoparticles and Zinc Sulfate Impact Physiological Parameters and Boosts Lipid Peroxidation in Soil Grown Coriander Plants (Coriandrum sativum).

The objective of this study was to determine the oxidative stress and the physiological and antioxidant responses of coriander plants (Coriandrum sativum) grown for 58 days in soil with zinc oxide nanoparticles (ZnO NPs) and zinc sulfate (ZnSO4) at concentrations of 0, 100, 200, 300, and 400 mg of Zn/kg of soil. The results revealed that all Zn compounds increased the total chlorophyll content (CHLt) by at least 45%, compared to the control group; however, with 400 mg/kg of ZnSO4, chlorophyll accumulation decreased by 34.6%. Zn determination by induction-plasma-coupled atomic emission spectrometry (ICP-AES) showed that Zn absorption in roots and shoots occurred in plants exposed to ZnSO4 at all concentrations, which resulted in high levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Only at 400 mg/kg of ZnSO4, a 78.6% decrease in the MDA levels was observed. According to the results, the ZnSO4 treatments were more effective than the ZnO NPs to increase the antioxidant activity of catalase (CAT), ascorbate peroxidase (APX), and peroxidases (POD). The results corroborate that phytotoxicity was higher in plants subjected to ZnSO4 compared to treatments with ZnO NPs, which suggests that the toxicity was due to Zn accumulation in the tissues by absorbing dissolved Zn++ ions.

Zinc supplementation alleviates endoplasmic reticulum stress during porcine oocyte in vitro maturation by upregulating zinc transporters.

Endoplasmic reticulum (ER) stress is a major contributor to embryonic development failure. Mammalian oocytes have a high risk of exposure to cellular stress during in vitro embryo production. We investigated the effects of zinc supplementation during in vitro maturation under ER stress. We evaluated cumulus expansion, embryonic development derived by parthenogenetic activation, reactive oxygen species, protein expression of X-box binding protein 1 (XBP1), and expression of genes related to ER stress. Supplementation with 1 µg/ml zinc significantly increased the nuclear maturation of oocytes, cleavage and blastocyst formation rates, and total blastocyst cell number (p < .05). Under ER stress, zinc significantly reduced protein expression of XBP1, and increased cleavage and blastocyst rates (p < .05). Concomitantly, zinc supplementation upregulated the expression of zinc transporters (SLC39A14 and SLC39A10), PTGS2, and downregulated ER stress-related genes (sXBP1, uXBP1, ATF4, and PTPN1/PTP1B), and caspase 3. These results suggest that zinc supplementation alleviates ER stress by providing essential metal-ion transporters for oocyte maturation and subsequent embryonic development.

Zinc ameliorates human aortic valve calcification through GPR39 mediated ERK1/2 signalling pathway.

AIMS: Calcific aortic valve disease (CAVD) is the most common heart valve disease in the Western world. It has been reported that zinc is accumulated in calcified human aortic valves. However, whether zinc directly regulates CAVD is yet to be elucidated. The present study sought to determine the potential role of zinc in the pathogenesis of CAVD. METHODS AND RESULTS: Using a combination of a human valve interstitial cell (hVIC) calcification model, human aortic valve tissues, and blood samples, we report that 20 µM zinc supplementation attenuates hVIC in vitro calcification, and that this is mediated through inhibition of apoptosis and osteogenic differentiation via the zinc-sensing receptor GPR39-dependent ERK1/2 signalling pathway. Furthermore, we report that GPR39 protein expression is dramatically reduced in calcified human aortic valves, and there is a significant reduction in zinc serum levels in patients with CAVD. Moreover, we reveal that 20 µM zinc treatment prevents the reduction of GPR39 observed in calcified hVICs. We also show that the zinc transporter ZIP13 and ZIP14 are significantly increased in hVICs in response to zinc treatment. Knockdown of ZIP13 or ZIP14 significantly inhibited hVIC in vitro calcification and osteogenic differentiation. CONCLUSIONS: Together, these findings suggest that zinc is a novel inhibitor of CAVD, and report that zinc transporter ZIP13 and ZIP14 are important regulators of hVIC in vitro calcification and osteogenic differentiation. Zinc supplementation may offer a potential therapeutic strategy for CAVD.

Production, characterization, and functions of sulfated polysaccharides from zinc sulfate enriched cultivation of Antrodia cinnamomea.

This research utilized zinc sulfate enriched cultural conditions to produce sulfated polysaccharides from Antrodia cinnamomea (denoted as ZnFSPS) and physiochemically characterize functional and mechanical investigations of ZnFSPS. The maximum SPS yield reached a value of 6.68% when A. cinnamomea was fed zinc sulfate with 250 mM (denoted as Zn250). Zn250 had a maximal inhibitory effect on LPS-induced tumor necrosis factor (TNF-α) release in RAW264.7 macrophage. Zn250 contained the highest area percentage of molecular weight of 178.5, 105.1, and 1.56 kDa at values of 19.08, 15.09, and 5.04. Zn250 contained three times the sulfate content as compared with the control. Mechanism studies revealed a novel finding that Zn250 inhibited the LPS-induced RAW264.7 macrophage inflammation and selectively blocked pAKT, pERK and p38. Zn250 also attenuated the LPS-induced IkB-α degradation. In addition, ZnFSPS interfered with lung cancer cell H1975 TGFRI/FAK/Slug signaling. These results suggest ZnFSPS plays roles in regulating inflammatory and anti-lung cancer activity.

Comparative digestibility of polysaccharide-complexed zinc and zinc sulfate in diets for gestating and lactating sows.

We hypothesized that the digestibility of a zinc polysaccharide complex is greater than zinc sulfate when sows consume high fiber diets containing corn dried distillers grains with solubles (DDGS). Gilts and sows (n = 32) were blocked according to parity and assigned randomly to one of four dietary treatments (n = 8 sows per treatments). Dietary treatments consisted of: 1) Control (ConZnSO4)-corn-soybean meal-based diet + 100 ppm supplemental Zn from ZnSO4; 2) Control PSZn (ConPSZn)-corn-soybean meal-based diet + 100 ppm supplemental Zn from Zn polysaccharide complex; 3) DDGS/ZnSO4-corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from ZnSO4; 4) DDGS/PSZn-corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from Zn polysaccharide complex. A fifth dietary treatment was imposed using a subset of sows (n = 20) to determine basal Zn losses in gestating and lactating sows fed corn-soybean meal-based diets containing no supplemental Zn. Nutrient balance experiments were conducted in both gestation and lactation to evaluate the digestibility of Zn sources of the four dietary treatments and to determine basal Zn losses when no supplemental Zn was provided. The statistical model included fixed effects of diet, Zn source, and their interaction, and random effects of parity. Estimated endogenous losses of Zn were used to adjust apparent total tract digestibility (ATTD) to true total tract digestibility (TTTD) of Zn in the four dietary treatment balance periods. There were no differences in Zn concentrations of urine, plasma, colostrum, or milk samples among treatments at any time of the experiment (P > 0.05). Gestating sows fed DDGS/PSZn had improved (P < 0.05) ATTD, TTTD, and overall retention of Zn compared with both Control treatments, with the DDGS/ZnSO4 treatment responses being intermediate. Lactating sows consuming diets without DDGS and supplemented with Zn polysaccharide complex had the greatest (P < 0.05) ATTD, TTTD, and retention of Zn, which were opposite to responses observed in gestation. Furthermore, ATTD, TTTD, and Zn retention for lactating sows consuming DDGS/PSZn were less (P < 0.05) than all other treatments. Overall, zinc digestibility of ZnSO4 and PSZn appears to be differentially influenced by the stage of the reproductive cycle and presence of dietary fiber from DDGS.

Zinc uptake from ZnSO4 (aq) and Zn-EDTA (aq) and its root-to-shoot transport in soybean plants (Glycine max) probed by time-resolved in vivo X-ray spectroscopy.

This study investigated the dynamic of zinc (Zn) uptake and the root-to-shoot Zn-transport when supplied as ZnSO4 (aq) or Zn-EDTA (aq) in soybean seedlings using in vivo X-ray fluorescence (XRF) and X-ray absorption spectroscopy (XANES). The time-resolved X-ray fluorescence showed that plants absorbed ca. 10-fold more Zn from ZnSO4 (aq) than from Zn-EDTA (aq). However, the uptake velocity did not influence the amount of Zn in the stem. It let furthermore appear that the plants were able to reduce the absorption of Zn from Zn-EDTA (aq) earlier than ZnSO4 (aq). Thus, the entrance of Zn2+ into the roots is not necessarily accompanied by SO42-(aq). Regardless the source, the Zn distribution and its transport in the stem were spatially correlated to the bundles and cortex nearby the epidermal cells. Its chemical speciation showed that Zn is neither transported as ZnSO4(aq) nor as Zn-EDTA(aq), indicating that these compounds are retained in the roots or biotransformed on in the root-solution interface. Zn2+ was long-distance transported complexed by organic molecules such as histidine, malate, and citrate, and the proportion of ligands was affected by the concentration of Zn2+ in the stem rather than by the type of Zn source.

Protein kinase CK2 is involved in zinc homeostasis in breast and prostate cancer cells.

The intracellular zinc profiles of breast and prostate cancer cells are diametrically opposed, with hyper-accumulation of zinc in breast cancer, and low level in prostate cancer. This phenomenon is poorly understood. This study employs two breast and two prostate cancer cell lines to investigate the role of protein kinase CK2 in regulating zinc homeostasis. CK2 was targeted by its specific inhibitors 4,5,6,7-tetrabromobenzotriazole (TBB) and CX-4945, and by the specific siRNA against each of the three CK2 genes. The effect of zinc exposure after the above CK2 manipulation was observed by MTT [3-(4,5-dimethyliazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] cell viability assay and confocal microscopy for intracellular zinc level. The results demonstrate that CK2 is involved in regulating zinc homeostasis in breast and prostate cancer cells as both TBB and CX-4945 substantially decreased cell viability upon zinc exposure. siRNA-mediated knockdown of the three CK2 subunits (α, α' and ß) revealed their discrete roles in regulating zinc homeostasis in breast and prostate cancer cells. Knockdown of CK2α' decreased the intracellular zinc level of breast cancer cells and in turn increased the cell viability while the opposite findings were obtained for the prostate cancer cells. Knockdown of CK2ß expression substantially increased the zinc level in breast cancer cell lines whilst decreased the zinc level in prostate cancer cells. Taken together, this study shows that CK2 is involved in zinc homeostasis of breast and prostate cancer cells and opens a new avenue for research on these cancers.

Zn homeostasis in genetic models of Parkinson's disease in Caenorhabditis elegans.

While the underlying mechanisms of Parkinson's disease (PD) are still insufficiently studied, a complex interaction between genetic and environmental factors is emphasized. Nevertheless, the role of the essential trace element zinc (Zn) in this regard remains controversial. In this study we altered Zn balance within PD models of the versatile model organism Caenorhabditis elegans (C. elegans) in order to examine whether a genetic predisposition in selected genes with relevance for PD affects Zn homeostasis. Protein-bound and labile Zn species act in various areas, such as enzymatic catalysis, protein stabilization pathways and cell signaling. Therefore, total Zn and labile Zn were quantitatively determined in living nematodes as individual biomarkers of Zn uptake and bioavailability with inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) or a multi-well method using the fluorescent probe ZinPyr-1. Young and middle-aged deletion mutants of catp-6 and pdr-1, which are orthologues of mammalian ATP13A2 (PARK9) and parkin (PARK2), showed altered Zn homeostasis following Zn exposure compared to wildtype worms. Furthermore, age-specific differences in Zn uptake were observed in wildtype worms for total as well as labile Zn species. These data emphasize the importance of differentiation between Zn species as meaningful biomarkers of Zn uptake as well as the need for further studies investigating the role of dysregulated Zn homeostasis in the etiology of PD.

Comparison study of zinc nanoparticles and zinc sulphate on wheat growth: From toxicity and zinc biofortification.

ZnO nanoparticles (NPs) are studied as a potential solution to alleviate Zn deficiency in human diet due to their special physicochemical properties. However, information for food quality and safety in NP-treated crops is limited. The effects of ZnO NPs and ZnSO4 on germination and growth of wheat (Triticum aestivum L.) were studied in germination and pot experiments. Zn content increased significantly, ZnO NPs were more effective than ZnSO4 at increasing grain Zn content, but less effective at increasing leaf Zn, and no ZnO NPs were detected in the wheat tissues by NP-treatments, indicated by XRD. Both ZnO NPs and ZnSO4 at moderate doses increased grain yield and biomass. Compared with control, the maximum grain yield and biomass of wheat treated with ZnO NPs and ZnSO4 were increased by 56%, 63% and 55%, 72%, respectively. ZnSO4 was more toxic than ZnO NPs at high doses as measured by the inhibitory effects in seed germination, root length, shoot length and dry biomass of seedlings. Structural damage in roots and variation in enzyme activities were greater with ZnSO4 than with ZnO NPs. ZnO NPs did not cause toxicity different from that of ZnSO4, which indicates that ZnO NPs used under the current experimental conditions did not cause Nano specific risks.

Design of High-Affinity Metal-Controlled Protein Dimers.

The ability to precisely control protein complex formation has high utility in the expanding field of biomaterials. Driving protein-protein binding through metal-ligand bridging interactions is a promising method of achieving this goal. Furthermore, the capacity to precisely regulate both complex formation and dissociation enables additional control not available with constitutive protein complexes. Here we describe the design of three metal-controlled protein dimers that are completely monomeric in the absence of metal yet form high-affinity symmetric homodimers in the presence of zinc sulfate. The scaffold used for the designed dimers is the ß1 domain of streptococcal protein G. In addition to forming high-affinity dimers in the presence of metal, the complexes also dissociate upon addition of EDTA. Biophysical characterization revealed that the proteins maintain relatively high thermal stability, bind with high affinity, and are completely monodisperse in the monomeric and dimeric states. High-resolution crystal structures revealed that the dimers adopt the target structure and that the designed metal-binding histidine residues successfully bind zinc and function to drive dimer formation.

Effects of foliar application of zinc sulfate and zinc nanoparticles in coffee (Coffea arabica L.) plants.

A greenhouse study comparing the physiological responses and uptake of coffee (Coffea arabica L.) plants to foliar applications of zinc sulfate (ZnSO4) and zinc nano-fertilizer (ZnO NPs) was conducted with the aim to understand their effects on plant physiology. One-year old coffee plants were grown in greenhouse conditions and treated with two foliar applications of 10 mg/L of Zn as either zinc sulfate monohydrate (ZnSO4 ‧ H2O) or zinc oxide nanoparticle (ZnO NPs 20% w/t) and compared to untreated control plants over the course of 45 days. ZnO NPs positively affected the fresh weight and dry weight (FW and DW) of roots and leaves, increasing the FW by 37% (root) and 95% (leaves) when compared to control. The DW increase was 28%, 85%, and 20% in roots, stems, and leaves, respectively. The net photosynthetic rate increased 55% in response to ZnO NPs treatment at the end of experiment when compared to control. ZnO NPs-treated leaves contained significantly higher amounts of Zn (1267.1 ±â€¯367.2 mg/kg DW) when compared to ZnSO4-treated plants (344.1 ±â€¯106.2 mg/kg DW), while control plants had the lowest Zn content in the leaf tissue (53.6 ±â€¯18.9 mg/kg DW). X-ray micro-analyses maps demonstrated the increased penetrance of ZnO NPs in coffee leaf tissue. Overall, ZnO NPs had a more positive impact on coffee growth and physiology than conventional Zn salts, which was most likely due to their increased ability to be absorbed by the leaf. These results indicate that the application of ZnO NPs could be considered for coffee systems to improve fruit set and quality, especially in areas where Zn deficiency is high.

Copper and zinc sources and levels of zinc inclusion influence growth performance, tissue trace mineral content, and carcass yield of broiler chickens.

A 35-d experiment was conducted in broilers to study the effect of supplementation of sulfate or hydroxychloride forms of Zn and Cu at 2 supplemental Zn levels on growth performance, meat yield, and tissue levels of Zn. On day 0, 900 male Ross 308 broiler chicks (45 ± 1.10 g) were allocated to 4 treatments in a randomized complete block design and 2 × 2 factorial arrangement of treatments. The factors were 2 sources (sulfate or hydroxychloride) of Zn and Cu and 2 levels (low or high) of Zn. The Zn sources were zinc sulfate monohydrate (ZSM) or hydroxychloride Zn. Copper sources were copper (II) sulfate pentahydrate or hydroxychloride Cu. Each of the 4 treatments had 15 replicates and 15 birds per replicate. Birds were weighed on days 0, 21, and 35 for growth performance. On day 35, left tibia bone, liver, and blood were collected from 4 randomly selected birds per pen. In addition, 7 birds per pen were used for carcass evaluation. There was no significant source × level interaction on any of the growth performance response. Broiler chickens receiving hydroxychloride Zn and Cu had greater (P < 0.05) gain: feed, whereas broiler chickens receiving lower Zn level had greater (P < 0.01) weight gain. There was no source × level interaction on meat yield. Broiler chickens receiving hydroxychloride Zn and Cu had greater (P < 0.05) % breast yield than those receiving sulfate Zn and Cu. Higher level of Zn, irrespective of source, produced greater (P < 0.01) tibia and plasma Zn levels, whereas liver Cu was greater (P < 0.05) in broiler chickens receiving hydroxychloride Zn and Cu. It was concluded that hydroxychloride Zn and Cu were more efficacious than sulfate Zn and Cu in promoting growth performance and enhancing meat yield in the current study.

Comparison of the Oral Absorption, Distribution, Excretion, and Bioavailability of Zinc Sulfate, Zinc Gluconate, and Zinc-Enriched Yeast in Rats.

SCOPE: The oral absorption, distribution, excretion, and bioavailability of zinc sulfate (ZnS), zinc gluconate (ZnG), and zinc-enriched yeast (ZnY) in rats are fully and systemically compared for the first time. METHODS AND RESULTS: After zinc compounds were orally administered to rats at a single dose of 4 mg Zn kg-1 , blood, tissues, urine, and feces at different time points were collected for the quantification of zinc concentration. Blood was also harvested for the zinc assay in the multiple-dose administration. Plasma zinc levels among three zinc compounds showed no difference, and zinc was widely distributed in various tissues with the level sequence of bone > liver > pancreas > testes. The net Zn balance was 2.993, 5.125, and 7.482% for ZnS, ZnG, and ZnY, respectively. CONCLUSION: ZnS, ZnG, and ZnY show equivalent bioavailability based on plasma and tissues zinc levels, although ZnY was statistically more absorbed and retained than ZnS and ZnG based on the excretion amount.