Zinc Supply Research Articles

Zinc deficiency impairs the development of human regulatory B cells from purified B cells

Zinc is a vital trace element, important for many different immune processes and adequate functionality. B cell development is known to be dependent on sufficient zinc supply. Recently a regulatory B cell (Breg) population has been identified, as CD19+IL-10+ B cells, able to regulate immune responses by secretion of anti-inflammatory cytokines, such as IL-10. Due to their promotion of an anti-inflammatory milieu, Bregs could reduce or might even prevent excessive pro-inflammatory responses. Hence, having and maintaining Bregs could be interesting for patients suffering from allergies, asthma, and autoimmune diseases. Therefore, understanding Breg generation, required signaling, and their developmental requirements are important. Since our group could previously show that zinc is important for regulatory T cells, we aimed to determine the effect of zinc deficiency on Breg development from human peripheral blood CD19+ B cells. We observed highest Breg generation with a combined stimulus of CD40L and the toll like receptor (TLR) ligand, CpG-ODN2006. Using this stimulus, we observed that zinc deficient medium significantly decreased Breg generation from purified B cells. This was not seen in Bregs generated from peripheral blood mononuclear cells (PBMCs) without B cell enrichment suggesting a compensatory mechanism. In line with literature, our data also confirms Bregs develop from CD19+ B cells, since total CD19+ frequencies remained unchanged, while Breg frequencies varied between stimuli and zinc media conditions. Our study shows for the first time that zinc deficiency significantly impairs Breg development, which provides an important new perspective for clinical applications and therapeutic strategies.

NRF2 and Thioredoxin Reductase 1 as Modulators of Interactions between Zinc and Selenium.

Selenium and zinc are essential trace elements known to regulate cellular processes including redox homeostasis. During inflammation, circulating selenium and zinc concentrations are reduced in parallel, but underlying mechanisms are unknown. Accordingly, we modulated the zinc and selenium supply of HepG2 cells to study their relationship. HepG2 cells were supplied with selenite in combination with a short- or long-term zinc treatment to investigate intracellular concentrations of selenium and zinc together with biomarkers describing their status. In addition, the activation of the redox-sensitive transcription factor NRF2 was analyzed. Zinc not only increased the nuclear translocation of NRF2 after 2 to 6 h but also enhanced the intracellular selenium content after 72 h, when the cells were exposed to both trace elements. In parallel, the activity and expression of the selenoprotein thioredoxin reductase 1 (TXNRD1) increased, while the gene expression of other selenoproteins remained unaffected or was even downregulated. The zinc effects on the selenium concentration and TXNRD activity were reduced in cells with stable NRF2 knockdown in comparison to control cells. This indicates a functional role of NRF2 in mediating the zinc/selenium crosstalk and provides an explanation for the observed unidirectional behavior of selenium and zinc.

ZnR/GPR39 Regulates Hepatic Insulin Signaling, Tunes Liver Bioenergetics and ROS Production, and Mitigates Liver Fibrosis and Injury

Adequate supply of zinc is essential for hepatic function and its deficiency is associated with acute liver injury (ALI) and chronic nonalcoholic fatty liver disease (NAFLD). However, how zinc controls hepatic function is unknown. We found that the zinc sensitive ZnR/GPR39, a mediator of zinc signaling, enhances hepatic phosphorylation of ERK1/2, which is reduced in ZnR/GPR39 deficient livers. Surprisingly, livers from ZnR/GPR39 knockout (KO) mice exhibited elevated insulin receptor expression and downstream AKT activation. Moreover, ZnR/GPR39 KO mice had higher blood fasting glucose level, pronounced hepatic lipid accumulation, increased hepatocyte oxygen consumption rate (OCR) and reactive oxygen species (ROS) levels. These data suggest that ZnR/GPR39 modulates insulin receptor signaling, a major pathway in hepatic metabolism. Associated with the impaired signaling, ZnR/GPR39 KO livers exhibited increased tissue fibrosis, manifested by marked elevation of collagen expression, compared to wildtype (WT). Additionally, we found alteration of hepatocyte junctional proteins that was accompanied by increased macrophage infiltration and higher liver inflammation in ZnR/GPR39 KO mice. To determine the role of ZnR/GPR39 in ALI, we applied a mild LPS challenge that induced profound decrease in hepatic OCR, also leading to higher ROS generation in ZnR/GPR39 KO hepatocytes, but not in WT. We further found increased serum IL-2 and AST/ALT ratio only in ZnR/GPR39 KO mice. Our findings reveal a role of ZnR/GPR39 in controlling hepatic insulin receptor signaling and mitigating liver fibrosis and inflammation, thus underscoring the important role of ZnR/GPR39 in liver signaling and function.

MEDICAGO sativa-mediated green synthesis of Zinc nano-complex: Impacts on the phytochemical properties of Hyssopus officinalis under Alkaline stress

The purpose of this study was to investigate the interaction between sodium bicarbonate stress (SBCS) (0, 10, 20, and 40 mM) and zinc nanocomplex (Zn NC) (0, 1, 2, and 4 mM) on the growth and bioactive compounds of Hyssopus officinalis L. plants at the growth stage. The application of Zn NC increased essential oil (EO) production and the biosynthesis of phenolic compounds (PCs) and flavonoids in the plant. The accumulation of these compounds amplified the plant's antioxidant capacity compared to control. Treatment with Zn NC increased these compounds significantly more than alkalinity. 2 mM and 4 mM Zn NCs increased average APX activity substantially by 37 % and 55 %, respectively. The oxidative damage and depletion of mineral nutrients in the leaves were caused by SBCS. However, Zn NC-treated plants significantly increased nitrogen, phosphorus, potassium, zinc, and iron concentrations in the bicarbonate-stressed plants. A 44 % increase in proline content with 20 mM SBCS and 4 mM Zn NCs compared to control was revealed. In alkaline soils, Zn NC can be a beneficial and environmentally acceptable zinc supply that increases plant growth and bioactive compound production. Totally, applying 2 and 4 mM Zn NC treatment can counteract the negative effects of SBCS on plant growth and nutrient uptake.

Dietary Organic Zinc Supplementation Modifies the Oxidative Genes via RORγ and Epigenetic Regulations in the Ileum of Broiler Chickens Exposed to High-Temperature Stress.

Heat stress (HS) is a significant concern in broiler chickens, which is vital for global meat supply in the dynamic field of poultry farming. The impact of heat stress on the ileum and its influence on the redox homeostatic genes in chickens remains unclear. We hypothesized that adding zinc to the feed of heat-stressed broilers would improve their resilience to heat stress. However, this study aimed to explore the effects of organic zinc supplementation under HS conditions on broiler chickens' intestinal histology and regulation of HS index genes. In this study, 512 Xueshan chickens were divided into four groups: vehicle, HS, 60 mg/kg zinc, and HS + 60 mg/kg zinc groups. Findings revealed that zinc supply positively increased the VH and VH: CD in the ileum of the broilers compared to the HS group, while CD and VW decreased in Zn and HS+Zn supplemented broilers. Zn administration significantly increased superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and decreased the enzymatic activities of reactive oxygen species (ROS) and malondialdehyde (MDA) compared to the HS group. In addition, Zn administration significantly increased relative ATP, complex I, III, and V enzyme activity compared to the HS group. Furthermore, the expression of acyl-CoA synthetase long-chain family member 4 (ACSL4), lactate transporter 3 (LPCAT3), peroxiredoxin (PRX), and transferrin receptor (TFRC) in the protein levels was extremely downregulated in HS+Zn compared to the HS group. Zn supply significantly decreased the enrichment of RORγ, P300, and SRC1 at target loci of ACSL4, LPCAT3, and PRX compared to the HS group. The occupancies of histone active marks H3K9ac, H3K18ac, H3K27ac, H3K4me1, and H3K18bhb at the locus of ACSL4 and LPCAT3 were significantly decreased in HS+Zn compared to the HS group. Moreover, H3K9la and H3K18la at the locus of ACSL4 and LPCAT3 were significantly decreased in HS+Zn compared to the HS group. This study emphasizes that organic Zn is a potential strategy for modulating the oxidative genes ACSL4, LPCAT3, PRX, and TFRC in the ileum of chickens via nuclear receptor RORγ regulation and histone modifications.

Zinc supply effects on wheat production in a low precipitation zone

AbstractZinc (Zn) fertilization of hard red and soft white winter wheat (Triticum aestivum L.) is uncommon in the low precipitation zone of the inland Pacific Northwest. It is uncommon because there have been no indications of deficiency. Soil test data, however, show Zn levels have been declining over time. We conducted a four‐site‐year experiment to evaluate effects of fertilization on early‐season tissue Zn concentration (TZC), dry matter accumulation (DMA), Zn uptake (ZNU), the grain test weight (TWT), protein content (PRO), and yield (YLD) of two regionally adapted cultivars. Planting occurred late in September or early in October. Zinc fertilizer, placed with the seed while planting, was applied at rates of 0 and 5 kg Zn ha−1. Application of 5 kg Zn ha−1 increased TZC and ZNU at one of two sites. There were corresponding trends of increased DMA and improved YLD. Response to fertilization occurred on a relatively shallow soil that had a diethylenetriamine‐pentaacidic acid–extractable Zn test level of 0.3 mg kg−1.

Effect of Zinc on Germination, Growth Yield of (Solanum melongena L.)

Eggplant (Solanum melongena L.) is an economically significant crop, valued for its culinary versatility and nutritional content. Understanding the factors that influence its growth is crucial for optimizing agricultural practices and improving yield. Zinc, an essential micronutrient, plays a vital role in various physiological processes within plants, including enzyme activation, photosynthesis, and hormone regulation. This study investigated the effect of zinc supplementation on the growth parameters of eggplant. The experiment was conducted in Botany Lab of Maharishi University of Information Technology, Lucknow in earthen Pots filled with garden soil. Where eggplant seedlings were subjected to different levels of zinc supplementation. Parameters such as plant height, leaf area, root development, and biomass accumulation were measured at regular intervals over the growth period. Results indicated a significant positive correlation between zinc concentration and various growth parameters of eggplant. Seedlings treated with higher zinc concentrations, enhanced leaf expansion, and more extensive root systems compared to those with lower or no zinc supplementation. Furthermore, zinc-treated eggplants displayed improved resistance to certain environmental stressors, suggesting a potential role of zinc in enhancing plant resilience. These findings underscore the importance of adequate zinc supply in promoting the growth and development of eggplant crops, thereby contributing to higher yields and improved agricultural sustainability. Further research is warranted to elucidate the underlying mechanisms of zinc-mediated growth enhancement in eggplant and optimize zinc application strategies for maximum benefit.

Influence of zinc supply on the course of infectious diarrhea in children of early age

Aim. Give a comparative characteristic of the course of infectious diarrhea in young children, residents of the Zaporizhzhia region (Ukraine), depending on their provision of zinc (Zn). Materials and methods. The study included 99 children aged 1 to 36 months with manifestations of infectious diarrhea. On the day of hospitalization, immunochromatographic and bacteriological examination of feces was performed. Also, on the first, third and fifth days of hospitalization, a general blood test and the level of Zn in the blood were determined for each patient. Results. It was found that among the examined patients with infectious diarrhea at the onset of the disease, 22 children (22.2 %) had a reduced concentration of Zn in blood serum. In these children, the zinc level ranged from 7.63 to 9.17 μmol/l. It was also noted that the level of Zn in these patients on the 5th day of inpatient treatment rose to the norm of reference indicators. After studying the anamnesis, it was found that 40.9% of children with low Zn content had episodes of acute intestinal infection before this disease. During a comparative analysis of the clinical and laboratory data of patients, it was found that the tendency to more frequent vomiting occurred in patients with Zn deficiency (p = 0.05), that Zn availability had the most significant effect on the expressiveness of the diarrheal syndrome at the onset of the disease and more than a third (n = 8, 36.4 %) of children with Zn deficiency had more than 5 episodes of diarrhea per day, among which every second had more than 10. We did not determine significant differences between the frequency of viral and bacterial causes of diarrhea in the comparison groups. As for complete blood count, patients with Zn deficiency more often had a tendency to blood neutrophilia with a reliably frequent shift of the leukocyte formula to the left (p = 0.003). At the same time, children with a reduced content of Zn in blood serum significantly more often had lymphopenia at the onset of diarrheal disease (p = 0.006). When investigating the effect of Zn deficiency on the course of the disease, we found that in children with reduced Zn, the duration of diarrhea was almost twice as long (8 [6; 9] days vs. 5 [4; 6] in children with normal Zn indicators; p = 0.0001 according to the Mann–Whitney test) and in patients with infectious diarrhea who had Zn deficiency at the onset of the disease, on the seventh day of treatment diarrhea persisted significantly more often (p = 0.03). Such symptoms were accompanied by the persistence of signs of anemia (p = 0.06 on the 5th day) and a shift of the leukocyte formula to the left (p = 0.007) without leukocytosis. Conclusions. Almost 25 % of young children with infectious diarrhea in the Zaporizhzhia region had Zn deficiency. Most likely, Zn deficiency is caused by the peculiarities of its supply with food and its metabolism. In the debut of a diarrheal disease, insufficient supply of Zn is associated with lymphopenia and a shift of the leukocyte formula to the left. Zn deficiency in infectious diarrhea leads to a long (more than 5 days) course of the disease due to prolongation of the diarrheal syndrome.

Toxicity effects of zinc supply on growth revealed by physiological and transcriptomic evidences in sweet potato (Ipomoea batatas (L.) Lam)

Zinc toxicity affects crop productivity and threatens food security and human health worldwide. Unfortunately, the accumulation patterns of zinc and the harmful effects of excessive zinc on sweet potato have not been well explored. In the present research, two genotypes of sweet potato varieties with different accumulation patterns of zinc were selected to analyze the effects of excessive zinc on sweet potato via hydroponic and field cultivation experiments. The results indicated that the transfer coefficient was closely related to the zinc concentration in the storage roots of sweet potato. Excessive zinc inhibited the growth of sweet potato plants by causing imbalanced mineral concentrations, destroying the cellular structure and reducing photosynthesis. Furthermore, a total of 17,945 differentially expressed genes were identified in the two genotypes under zinc stress by transcriptomic analysis. Differentially expressed genes involved in the absorption and transport of zinc, defense networks and transcription factors played important roles in the response to zinc stress. In conclusion, this study provides a reference for the selection of sweet potato varieties in zinc contaminated soil and lays a foundation for investigating the tolerance of sweet potato to excessive zinc, which is meaningful for environmental safety and human health.

Metabolomics reveals the impact of nitrogen combined with the zinc supply on zinc availability in calcareous soil via root exudates of winter wheat (Triticum aestivum)

A possible mechanism for the improved availability of zinc (Zn) in soil by combining nitrogen (N) with Zn supply was investigated based on the root exudates of winter wheat. N, Zn supply as well as their combination significantly regulated nine root exudates in winter wheat; in which, the secretion of cis-aconitic acid involving in the TCA cycle, C5-branched dibasic acid metabolism, glyoxylate and dicarboxylate metabolism and 2-oxocarboxylic acid metabolism was upregulated by N, Zn supply as well as their combination. N–Zn combination induced the activities of citrate synthase and cis-aconitase in roots and shoots of winter wheat thus to increase the concentrations of citric and aconitic acid; the decrease of isocitric acid concentrations in shoots indicated the inhibited conversion of aconitic acid to isocitric acid by N–Zn combination. It revealed a possible reason for the enhanced secretion of cis-aconitic acid by N–Zn combination. Exogenous addition of 10 μ plant−1 cis-aconitate significantly increased available Zn concentrations in soil and Zn concentrations in winter wheat under N–Zn combination. Thus, the N–Zn combination regulated the metabolism of cis-aconitic acid in winter wheat, thus enhancing the secretion of cis-aconitic acid to increase the bioavailability of Zn in soil.

Suboptimal zinc supply affects the S-nitrosoglutathione reductase enzyme and nitric oxide signaling in Arabidopsis

The S-nitrosoglutathione reductase (GSNOR), a key regulator of nitric oxide (NO) signaling, requires zinc (Zn) cofactors for its catalytic activity. Possible changes in GSNOR function and NO signaling due to limited Zn supply and participation of GSNOR in response to Zn deficiency have not yet been examined. The wild-type Arabidopsis thaliana seedlings (Col-0) and the overproducer of GSNOR (35S::FLAG-GSNOR1) were grown in agar medium supplemented with 15 µM (full Zn), 1.5 µM (Zn/10) and 0 µM (Zn0) zinc sulfate. Limited availability of Zn in the nutrient medium during the experimental period resulted in a significantly reduced Zn content in the roots and shoots of Arabidopsis and altered the expression of Zn deficiency marker genes; however, the Zn content did not reflect Zn deficiency in the seedlings. GSNOR has no effect on the Zn limitation-induced reduction in the in planta Zn content. Suboptimal Zn supply results in a smaller but more active GSNOR protein pool in Col-0 A. thaliana. In 35S::FLAG-GSNOR1, overproduction possibly compensates for the negative effects of reduced Zn supply, resulting in unchanged GSNOR expression, protein abundance, and activity. Suboptimal Zn supply alters NO but did not modify peroxynitrite and hydrogen peroxide levels and exerts a pronitrant effect in the plant proteome. Overall, this is the first report to show that limited Zn supply affects the GSNOR enzyme at the gene and protein levels but not at the activity level and modifies reactive species levels and physiological nitroproteome in Arabidopsis.

Transcriptional Response of Burkholderia cenocepacia H111 to Severe Zinc Starvation.

Burkholderia cenocepacia is an opportunistic pathogen that is primarily associated with severe respiratory infections in people with cystic fibrosis. These bacteria have significant intrinsic resistance to antimicrobial therapy, and there is a need for more effective treatments. Bacterial zinc uptake and homeostasis systems are attractive targets for new drugs, yet our understanding of how bacteria acquire and utilise zinc remains incomplete. Here we have used RNA-sequencing and differential gene expression analysis to investigate how B. cenocepacia H111 is able to survive in zinc poor environments, such as those expected to be encountered within the host. The data shows that 201 genes are significantly differentially expressed when zinc supply is severely limited. Included in the 85 upregulated genes, are genes encoding a putative ZnuABC high affinity zinc importer, two TonB-dependent outer membrane receptors that may facilitate zinc uptake across the outer cell membrane, and a COG0523 family zinc metallochaperone. Amongst the 116 downregulated genes, are several zinc-dependent enzymes suggesting a mechanism of zinc sparring to reduce the cells demand for zinc when bioavailability is low.

Mapping QTL for Mineral Accumulation and Shoot Dry Biomass in Barley under Different Levels of Zinc Supply.

Zinc (Zn) deficiency is a common limiting factor in agricultural soils, which leads to significant reduction in both the yield and nutritional quality of agricultural produce. Exploring the quantitative trait loci (QTL) for shoot and grain Zn accumulation would help to develop new barley cultivars with greater Zn accumulation efficiency. In this study, two glasshouse experiments were conducted by growing plants under adequate and low Zn supply. From the preliminary screening of ten barley cultivars, Sahara (0.05 mg/pot) and Yerong (0.06 mg/pot) showed the lowest change in shoot Zn accumulation, while Franklin (0.16 mg/pot) had the highest change due to changes in Zn supply for plant growth. Therefore, the double haploid (DH) population derived from Yerong × Franklin was selected to identify QTL for shoot mineral accumulation and biomass production. A major QTL hotspot was detected on chromosome 2H between 31.91 and 73.12 cM encoding genes for regulating shoot mineral accumulations of Zn, Fe, Ca, K and P, and the biomass. Further investigation demonstrated 16 potential candidate genes for mineral accumulation, in addition to a single candidate gene for shoot biomass in the identified QTL region. This study provides a useful resource for enhancing nutritional quality and yield potential in future barley breeding programs.

Examining energy and nutrient production across the different agroecological zones in rural Ethiopia using statistical methods.

Poor-quality diets are of huge concern in areas where consumption is dominated by locally sourced foods that provide inadequate nutrients. In agroecologically diverse countries like Ethiopia, food production is also likely to vary spatially. Yet, little is known about how nutrient production varies by agroecology. Our study looked at the adequacy of essential nutrients from local production in the midland, highland, and upper highland agroecological zones (AEZs). Data were collected at the village level from the kebele agriculture office and at the farm and household levels through surveys in rural districts of the South Wollo zone, Ethiopia. Household data were acquired from 478 households, and crop samples were collected from 120 plots during the 2020 production year. Annual crop and livestock production across the three AEZs was converted into energy and nutrient supply using locally developed crops' energy and nutrient composition data. The total produced energy (kcal) met significant proportions of per capita energy demand in the highland and upper highland, while the supply had a 50% energy deficit in the midland. Shortfalls in per capita vitamin A supply decreased across the agroecological gradient from midland (46%) to upper highland (31%). The estimated shortfall in folate supply was significantly higher in the upper highlands (63%) and negligible in the highlands (2%). The risk of deficient iron and zinc supply was relatively low across all AEZs (<10%), but the deficiency risk of calcium was unacceptably high. Agroecology determines the choice of crop produced and, in this way, affects the available supply of energy and nutrients. Therefore, agroecological variations should be a key consideration when designing food system interventions dedicated to improving diets.

Synergetic adsorption of dodecylamine and octyl hydroxamic acid on sulfidized smithsonite: Insights from experiments and molecular dynamics simulation

The escalating demand for zinc resources has been positioning zinc oxide ore as an invaluable supplementary resource to cater to zinc supply requirements. There is now a growing focus on optimizing the efficient flotation of zinc oxide ore. In this study, experiments were conducted using dodecylamine (DDA) and octyl hydroxamic acid (OHA) as combined collectors, along with pre-sulfidization by sodium sulfide, to enhance smithsonite flotation. The use of the DDA–OHA combined collector resulted in a significant improvement of over 25% in the recovery when compared with the use of DDA as a single collector. Adsorption capacity measurements and zeta potential measurements provided evidence for the synergistic effect of DDA and OHA. Solution surface tension measurements indicated that the combined collector system helped stabilize the flotation foam. Analysis of treated smithsonite by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy further verified the chemical and physical adsorption of DDA and OHA on the surface of smithsonite. The measurement of contact angles of treated smithsonite showed that the combined collector effectively increased the hydrophobicity of the mineral. Molecular dynamics simulations suggested that OHA and DDA undergo multilayer adsorption on the sulfidized smithsonite (101) surface and that the presence of OHA promotes the adsorption of DDA.

Zinc supply influences the root-specific traits with the expression of root architecture modulating genes in millets

Zinc supply influences the root-specific traits with the expression of root architecture modulating genes in millets

Combined transcriptome and proteome analysis revealed the molecular regulation mechanisms of zinc homeostasis and antioxidant machinery in tobacco in response to different zinc supplies

Zinc (Zn) is an essential micronutrient for plants. Adequate regulation of Zn uptake, transport and distribution, and adaptation to Zn-deficiency stress or Zn-excess toxicity are crucial for plant growth and development. However, little has been done to understand the molecular responses of plants toward different Zn supply levels. In the present study, we investigated the growth and physiological responses of tobacco seedlings grown under Zn-completely deficient, Zn-limiting, Zn-normal, and Zn-4-fold sufficient conditions, respectively, and demonstrated that Zn deficiency/limitation caused oxidative stress and impaired growth of tobacco plants. Combined transcriptome and proteome analysis revealed up-regulation of genes/proteins associated with Zn uptake and distribution, including ZIPs, NAS3s, and HMA1s, and up-regulation of genes/proteins involved in regulation of oxidative stress, including SODs, APX1s, GPX6, and GSTs in tobacco seedlings in response to Zn deficiency/limitation, suggesting that tobacco possessed mechanisms to regulate Zn homeostasis primarily through up-regulation of the ZIPs–NAS3s module, and to alleviate Zn deficiency/limitation-induced oxidative stress through activation of the antioxidant machinery. Our results provide novel insights into the adaptive mechanisms of tobacco in response to different Zn supplies, and would lay a theoretical foundation for development of varieties of tobacco or its relatives with high tolerance to Zn-deficiency.

Sol–gel deposition of Al-doped ZnO thin films: effect of additional zinc supply

Sol–gel deposition of Al-doped ZnO thin films: effect of additional zinc supply

Zinc Supply Affects Cadmium Uptake and Translocation in the Hyperaccumulator Sedum Plumbizincicola as Evidenced by Isotope Fractionation.

This study employs stable isotope analysis to investigate the mechanisms of cadmium (Cd) and zinc (Zn) interaction in the metal hyperaccumulating plant species Sedum plumbizincicola. To this end, the Cd and Zn isotope compositions of root, stem, leaf, and xylem sap samples were determined during metal uptake and translocation at different Cd and Zn concentrations. The enrichment of light isotopes of both elements in plants during uptake was less pronounced at low metal supply levels, likely reflecting the switch from a low-affinity to a high-affinity transport system at lower levels of external metal supply. The lower δ114/110Cd values of xylem sap when treated with a metabolic inhibitor decreasing the active Cd uptake further supports the preference of heavier Cd isotopes during high-affinity transport. The Δ66Znplant-initialsolution or Δ66Znplant-finalsolution values were similar at different Cd concentrations, indicating negligible interaction of Cd in the Zn uptake process. However, decreasing Zn supply levels significantly increased the enrichment of light Cd isotopes in plants (Δ114/110Cd = -0.08‰) in low-Cd treatments but reduced the enrichment of light Cd isotopes in plants (Δ114/110Cd = 0.08‰) under high Cd conditions. A systematic enrichment of heavy Cd and light Zn isotopes was found in root-to-shoot translocation of the metals. The Cd concentrations of the growth solutions thereby had no significant impact on Zn isotope fractionation during root-to-shoot translocation. However, the Δ114/110Cdtranslocation values hint at possible competition between Cd and Zn for transporters during root-to-shoot transfer and this may impact the transport pathway of Cd. The stable isotope data demonstrate that the interactions between the two metals influenced the uptake and transport mechanisms of Cd in S. plumbizincicola but had little effect on those of Zn.

The effect of extreme weather events on child nutrition and health

This study traces the causal effects of extreme weather events on nutritional and health outcomes among rural children in Uganda using four waves of individual child survey data (2009–2014). A simultaneous regression model was applied for causal inference while also accounting for households’ adaptive responses. The study finds the evidence of a significant negative relationship between extreme weather events and availability of calories and nutrients for children. In particular, droughts reduced calorie, protein and zinc supply, and overall diet diversity by 67%, 37%, 28% and 30%, respectively. We further traced the effects of this reduced calorie and nutrient availability on child health indicators. A 10% decrease in zinc supply decreased height-for-age z-scores (HAZ) by around 0.139 - 0.164 standard deviations (SD), and increased probability of stunting ranging from 3.1 to 3.5 percentage points. Both boys and girls HAZ and stunting rates were sensitive to nutrient inadequacies. Different coping and adaptation strategies significantly influenced rural households’ ability to safeguard children’s nutrition and health against the effects of extreme weather. The findings of this study provide specific insights for building ex-ante resilience against extreme weather events, particularly when compared to ex-post, unsustainable, and often costlier relief actions.