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Elucidating the migration processes of zinc (Zn) is crucial for comprehending its influence on global biogeochemical cycling. However, significant gaps remain in the knowledge of these processes in glacier-fed rivers of the northeast Tibetan Plateau (NETP). This study determined the isotopic compositions (δ 66 Zn) of dissolved and particulate Zn in three alpine rivers fed by the Laohugou Glacier (LHG), the Lenglongling Glacier (LG), and the Yuzhufeng Glacier (YG) in the NETP. Results show that the δ 66 Zn of particulate Zn varies from -0.01 ± 0.04 to +0.97 ± 0.12‰, generally higher than that of dissolved Zn (-0.82 ± 0.06 to +0.19 ± 0.03‰). This suggests a migration behavior in which isotopically lighter Zn is enriched in the dissolved phase and isotopically heavier Zn preferentially adsorbs onto the particulate matter. Moreover, the δ 66 Zn in the dissolved phase exhibits obvious spatial variation, with an upward trend from the LHG-fed river to the YG-fed river and subsequently to the LG-fed river. In contrast, this trend is less pronounced in the particulate phase due to an anomalously high δ 66 Zn value (0.97 ± 0.12‰). This isotopic anomaly is primarily attributed to anthropogenic impacts. A comparison with global terrestrial aquatic environments emphasizes the unique response of Zn isotope variability in NETP glacier-fed rivers to both migration processes and anthropogenic impacts.

Magnesium (Mg) and zinc (Zn) are essential nutrients for plants. Mg deficiency often occurs in rice plants grown in Zn-polluted soil. However, the mechanism for this correlation is unclear. Here, we performed culture experiments on rice plants (Oryza sativa L.) and used Mg isotopes to investigate mechanisms of Zn stress on plant Mg deficiency. Our results show that excess Zn can significantly reduce the uptake of Mg in rice tissues. The root displays positive Δ 26 Mg plant-nutrient values (δ 26 Mg plant -δ 26 Mg nutrient ; 1.90 ‰ to 2.06 ‰), which suggests that Mg enters the root cells mainly via Mg-specific transporters rather than non-selective diffusion. The decreased Δ 26 Mg plant-nutrient values with increasing Zn supply can be explained by the competition between Zn and Mg, both of which combine with same transporters in roots. In contrast, the shoots (stem and leaf) display much lower δ 26 Mg values than roots, which suggests that the transport of Mg from roots to aerial biomass is mainly via free Mg ions, during which Zn cannot competitively inhibit the movement of Mg. Our study suggests that the Mg deficiency in rice plants can be caused by high Zn-levels in soils and highlights the necessity of soil Zn-remediation in solving Mg deficiency problems in rice plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Metallothioneins (MTs) are cysteine-rich proteins involved in metal homeostasis, heavy metal detoxification, and protection against oxidative stress. Whether the four mammalian MT isoforms exhibit different metal binding properties is not clear. In this paper, the Cu(I) binding properties of the apo MT1A, apo MT2, and apo MT3 are compared and the relative Cu(I) binding affinities are reported. In all three isoforms, Cu4, Cu6, and Cu10 species form cooperatively, and MT1A and MT2 also form a Cu13 species. The Cu(I) binding properties of Zn7-MT1A, Zn7-MT2, and Zn7-MT3 are compared systematically using isotopically pure 63Cu(I) and 68Zn(II). The species formed in each MT isoform were detected through electrospray ionization-mass spectrometry and further characterized using room temperature phosphorescence spectroscopy. The mixed metal Cu, Zn species forming in MT1A, MT2, and MT3 have similar stoichiometries and their emission spectral properties indicate that analogous clusters form in the three isoforms. Three parallel metallation pathways have been proposed through analysis of the detailed Cu, Zn speciation in MT1A, MT2, and MT3. Pathway ① results in Cu5Zn5-MT and Cu9Zn3-MT. Pathway ② involves Cu6Zn4-MT and Cu10Zn2-MT. Pathway ③ includes Cu8Zn4-MT. Speciation analysis indicates that Pathway ② is the preferred pathway for MT2. This is also evident in the phosphorescence spectra with the 750 nm emission from Cu6Zn4-MT being most prominent in MT2. We see no evidence for different MT isoforms being optimized or exhibiting preferences for certain metals. We discuss the probable stoichiometry for MTs in vivo based on the in vitro determined binding constants., (© The Author(s) 2024. Published by Oxford University Press.)

In sum, 11 (p,xn) related nuclear reactions with 9 target materials, namely 18O(p,n)18F, 15N(p,n)15O, 68Zn(p,n)68Ga, 68Zn(p,2n)67Ga, 69Ga(p,2n)68Ge, 89Y(p,n)89Zr, 100Mo(p,pn)99Mo, 100Mo(p,2n)99mTc, 112Cd(p,2n)111In, 124Xe(p,2n)123Cs and 203Tl(p,3n)201Pb, are involved in the operation of 13 radionuclide-production cyclotrons in Taiwan. The secondary neutrons accompanying these production routes could induce varying degrees of material activation in the cyclotron facility. Accordingly, this study compared the effects of various (p,xn) production routes on the neutron-induced long-lived radioactivity in the concrete walls of a hypothetical cyclotron vault. In addition, an activation-reduction approach involving the addition of a layer of neutron-absorbing material to the surface of inner concrete walls was evaluated., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Metallothionein proteins are essential for Cu(I) and Zn(II) homeostasis as well as heavy metal detoxification. The metallation properties of MT2 are of great interest due to their wide patterns of expression and correlation with multiple diseases including cancers, neurological disorders, and respiratory diseases. Use of isotopically pure 63Cu(I) and 68Zn(II) eliminates the complexity of the Cu, Zn-MT2 mass spectral peaks due to significant overlap of naturally abundant isotopes. This allows for the resolution of the precise Cu(I) and Zn(II) stoichiometries when both Cu(I) and Zn(II) are bound to MT2 at physiological pH as expected in vivo. Exact Cu: Zn ratios were determined from mass spectral simulations carried out for every point in the titration. We report that Cu(I) metallation of Zn7-MT2 can only be understood in terms of two pathways occurring in parallel with pathway ① resulting in Cu5Zn5-MT2 and Cu9Zn3-MT2. Pathway ② results in Cu6Zn4-MT2 and Cu10Zn2-MT2, which are the major products of the reaction. From the electrospray ionization (ESI)-mass spectral data we report a series of formation constants (KF) for species starting from Zn7-MT2 up to Cu11Zn2-MT2. Room temperature phosphorescence and circular dichroism (CD) spectra were measured in parallel with the ESI-mass spectrometry data allowing for the assignment of specific species to specific spectral bands. Through analysis of the CD spectral bands, we propose that Cu(I) binds to the β domain first to form a Cu5Zn1 cluster or Cu6 cluster with emission at 670 and 750 nm, respectively, leaving the Zn4 cluster in the α domain., (© The Author(s) 2023. Published by Oxford University Press.)

Improving urban air quality is a global challenge. To implement successful abatement measures that reduce atmospheric particulate matter (APM) and associated metal concentrations, precise source apportionment is needed. For this, apportioning contributions from coal and biomass burning and differentiating these from non-exhaust traffic emissions in urban APM is critical. Recent studies characterising the metal isotope composition of urban APM, and potential source materials suggested that non-traditional isotope systems could prove unique fingerprinting tools. Zinc isotopes should be able to separate APM derived from uncontrolled combustion (fly ash, isotopically heavy) from non-exhaust traffic sources (tyre and brake wear, intermediate) and from controlled industrial emissions (flue gas, light). To test this hypothesis, we determined zinc isotope ratios of APM (TSP, PM 2.5 , PM 1 ) in Beijing (coal combustion for residential heating) and Varanasi (biomass burning in pre-monsoon periods). In Beijing, δ 66 Zn Lyon values of PM 2.5 ranged from -0.41 to +1.01‰ in 2015 (avg = +0.25 ± 0.50‰, n = 19). Aerosols (including TSP, PM 2.5 and PM 1 samples) from the heating period were significantly (t-test, p < 0.001) heavier (avg = +0.90 ± 0.12‰, n = 7) than those from the non-heating period (avg = +0.14 ± 0.36‰, n = 23). Average δ 66 Zn Lyon values of PM 2.5 in Varanasi in spring 2015 were +0.82 ± 0.11‰ (n = 4). Extent and direction of isotope fractionation is in line with that expected from theoretical models and the isotope signatures observed agree with previously determined ratios of source materials. Our study links for the first time comprehensively the heavy zinc isotope compositions in APM to coal and biomass burning and shows that zinc isotope compositions of aerosols can discriminate between non-exhaust traffic and combustion sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Trophic ecology and resource use are challenging to discern in migratory marine species, including sharks. However, effective management and conservation strategies depend on understanding these life history details. Here we investigate whether dental enameloid zinc isotope (δ 66 Zn en ) values can be used to infer intrapopulation differences in foraging ecology by comparing δ 66 Zn en with same-tooth collagen carbon and nitrogen (δ 13 C coll , δ 15 N coll ) values from critically endangered sand tiger sharks (Carcharias taurus) from Delaware Bay (USA). We document ontogeny and sex-related isotopic differences indicating distinct diet and habitat use at the time of tooth formation. Adult females have the most distinct isotopic niche, likely feeding on higher trophic level prey in a distinct habitat. This multi-proxy approach characterises an animal's isotopic niche in greater detail than traditional isotope analysis alone and shows that δ 66 Zn en analysis can highlight intrapopulation dietary variability thereby informing conservation management and, due to good δ 66 Zn en fossil tooth preservation, palaeoecological reconstructions., (© 2023. The Author(s).)

Transect sampling is an under-exploited tool in isotope studies of atmospheric pollution. Few studies have combined Zn and Pb isotope ratios to investigate whether atmospheric pollution at a receptor site is dominated by a different anthropogenic source of each of these toxic elements. It has been also unclear whether pollution abatement strategies in Central Europe have already resulted in regionally well-mixed background isotope signature of atmospheric Zn and Pb. Zinc and lead isotope ratios were determined in snow collected along a rural transect downwind from the Upper Silesian industrial area (southern Poland). Spatial and temporal gradients in δ 66 Zn and 206 Pb/ 207 Pb ratios at four sites were compared with those of ore and coal collected in eight Czech and Polish mining districts situated at distances of up to 500 km. Snow pollution was extremely high 8 km from Olkusz in 2011 (1670 μg Zn L -1 ; 240 μg Pb L -1 ), sharply decreased between 2011 and 2018, and remained low in 2019-2021. Snow pollution was lower at sites situated 28-68 km from Olkusz. Across study sites, mean δ 66 Zn and 206 Pb/ 207 Pb ratios of snow were -0.13‰ and 1.155, respectively. With an increasing distance from Olkusz, the δ 66 Zn values first increased and then decreased, while the 206 Pb/ 207 Pb ratios first decreased and then increased. The δ 66 Zn values in snow plotted closer to those of Upper Silesian ores (-0.20‰) than to the δ 66 Zn values of Upper Silesian stone coal (0.52‰), showing predominance of smelter-derived over power-plant derived Zn pollution. The 206 Pb/ 207 Pb ratios of Upper Silesian coal (1.171) and Upper Silesian ores (1.180) were higher compared to those of snow. A 206 Pb/ 207 Pb vs. 208 Pb/ 207 Pb plot identified legacy pollution from leaded gasoline as the low-radiogenic mixing end-member. Across the transect sites, only the last sampling campaign exhibited a high degree of isotope homogenization for both Zn and Pb., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Zinc (Zn) is an important micronutrient but can be toxic at elevated concentrations. We conducted an experiment to test the effect of plant growth and soil microbial disturbance on Zn in soil and plants. Pots were prepared with and without maize and in an undisturbed soil, a soil that was disturbed by X-ray sterilization and a soil that was sterilized but reconditioned with the original microbiome. The Zn concentration and isotope fractionation between the soil and the soil pore water increased with time, which is probably due to physical disturbance and fertilization. The presence of maize increased the Zn concentration and isotope fractionation in pore water. This was likely related to the uptake of light isotopes by plants and root exudates that solubilized heavy Zn from the soil. The sterilization disturbance increased the concentration of Zn in the pore water, because of abiotic and biotic changes. Despite a threefold increase in Zn concentration and changes in the Zn isotope composition in the pore water, the Zn content and isotope fractionation in the plant did not change. These results have implications for Zn mobility and uptake in crop plants and are relevant in terms of Zn nutrition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

68 Ga is produced from enriched zinc-68 target electrodeposited on copper base material which was irradiated with 15 MeV proton energy in 30 MeV cyclotron. A modified semi-automated separation and purification module was used to obtain pharmaceutical grade [ 68 Ga]GaCl 3 in 35 ± 5 min. The quality of [ 68 Ga]GaCl 3 produced was in accordance with Pharmeuropa 30.4. The [ 68 Ga]GaCl 3 was utilized for the formulation of multiple doses of [ 68 Ga]Ga-PSMA-11 and [ 68 Ga]Ga-DOTATATE. The quality of [ 68 Ga]Ga-PSMA-11 and [ 68 Ga]Ga-DOTATATE were also in accordance with Pharmacopeia., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Modified 241 Am-Be neutron beams showed an ability to change the optical properties of zinc oxide (ZnO) photoluminescence (PL) spectra by transmuting zinc (Zn) into gallium (Ga) after irradiation. This study investigates the time required by slow neutron irradiation to register the transmutation of the Zn into Ga. Two series of samples from different suppliers hydrothermally (HT) grown by TEW Tokyo Denpa Co. Ltd., Tokyo, Japan, and MTI corporation, China, are irradiated for 6, 12, 18, and 24 days on the Zn-polar face of each sample to specify the relationship between the irradiation intensity and transmutation.

The Zn isotope fingerprint is widely used as a proxy of various environmental geochemical processes, so it is crucial to determine which are the mechanisms responsible for isotopic fractionation. Iron (Fe) (hydr)oxides greatly control the cycling and fate and thus isotope fractionation factors of Zn in terrestrial environments. Here, Zn isotope fractionation and related mechanisms during adsorption on and substitution in three FeOOH polymorphs are explored. Results demonstrate that heavy Zn isotopes are preferentially enriched onto solids, with almost similar isotopic offsets (Δ 66/64 Zn solid-solution = 0.25-0.36‰) for goethite, lepidocrocite, and feroxyhyte. This is consistent with the same average Zn-O bond lengths for adsorbed Zn on these solids as revealed by Zn K-edge X-ray absorption fine structure spectroscopy. In contrast, at an initial Zn/Fe molar ratio of 0.02, incorporation of Zn into goethite and lepidocrocite by substituting for lattice Fe preferentially sequesters light Zn isotopes with Δ 66/64 Zn substituted-stock solution of -1.52 ± 0.09‰ and -1.18 ± 0.15‰, while Zn-substituted feroxyhyte (0.06 ± 0.11‰) indicates almost no isotope fractionation. This is closely related to the different crystal nucleation and growth rates during the Zn-doped FeOOH formation processes. These results provide direct experimental evidence of incorporation of isotopically light Zn into Fe (hydr)oxides and improve our understanding of Zn isotope fractionation mechanisms during mineral-solution interface processes.

This study aims to establish whether zinc (Zn) and cadmium (Cd) share similar physiological mechanisms for uptake and translocation in cacao plants (Theobroma cacao L.). Multiple-collector ICP-MS was used to determine the Zn stable isotope compositions in the roots, stems and leaves of 19 diverse cacao genotypes grown in hydroponics with 20 µmol L -1 CdCl 2 . Additional plants of one genotype were grown in hydroponic solutions containing lower Cd concentrations (0 and 5 µmol L -1 added CdCl 2 ). Regardless of the Cd concentration used in the exposures, the Zn stable isotope compositions show the same systematic patterns in plant organs, with δ 66 Zn root  > δ 66 Zn stem  > δ 66 Zn leaf (δ 66 Zn denotes relative differences in 66 Zn/ 64 Zn ratios in parts per thousand). The mean Zn stable isotope fractionation between the plants and the hydroponic solutions was ε 66 Zn uptake  = -1.15 ± 0.36‰ (2SD), indicating preferential uptake of isotopically light Zn by plants from the hydroponic solution. The mean  stable isotope fractionation factor associated with translocation of Zn from roots to shoots, ε 66 Zn seq-mob  =  + 0.52 ± 0.36‰ (2SD), shows that isotopically heavy Zn is preferentially sequestered in the cacao roots, whilst isotopically light Zn is mobilised to the leaves. A comparison with the Cd stable isotope compositions of the same plants shows that both isotopically light Zn and Cd are preferentially taken up by cacao plants. In contrast to Zn, however, the cacao roots retain isotopically light Cd and transfer isotopically heavy Cd to the leaves., (© 2023. The Author(s).)

Mammalian metallothioneins (MTs) are important proteins in Zn(II) and Cu(I) homeostasis with the Zn(II) and Cu(I) binding to the 20 cysteines in metal-thiolate clusters. Previous electrospray ionization (ESI) mass spectrometric (MS) analyses of Cu(I) binding to Zn7-MT were complicated by significant overlap of the natural abundance isotopic patterns for Zn(II) and Cu(I) leading to impossibly ambiguous stoichiometries. In this paper, isotopically pure 63Cu(I) and 68Zn(II) allowed determination of the specific stoichiometries in the 68 Zn,63Cu-βα MT1A species formed following the stepwise addition of 63Cu(I) to 68Zn7-βα MT1A. These species were characterized by ESI-MS and room temperature emission spectroscopy. The key species that form and their emission band centres are Zn5Cu5-βα MT1A (λ = 684 nm), Zn4Cu6-βα MT1A (λ = 750 nm), Zn3Cu9-βα MT1A (λ = 750 nm), Zn2Cu10-βα MT1A (λ = 750 nm), and Zn1Cu14-βα MT1A (λ = 634 nm). The specific domain stoichiometry of each species was determined by assessing the species forming following 63Cu(I) addition to the 68Zn3-β MT1A and 68Zn4-α MT1A domain fragments. The domain fragment emission suggests that Zn5Cu5-βα MT1A contains a Zn1Cu5-β cluster and the Zn4Cu6-βα MT1A, Zn3Cu9-βα MT1A, and Zn2Cu10-βα MT1A each contain a Cu6-β cluster. The species forming with >10 mol. eq. of 63Cu(I) in βα-MT1A exhibit emission from the Cu6-β cluster and an α domain cluster. This high emission intensity is seen at the end of the titrations of 68Zn7-βα MT1A and the 68Zn4-α MT1A domain fragment suggesting that the initial presence of the Zn(II) results in clustered Cu(I) binding in the α domain., (© The Author(s) 2023. Published by Oxford University Press.)

Land use change threatens food security because it may cause the depletion and/or low bioavailability of micronutrients in agricultural soils. Therefore, it is significant to investigate the fate of micronutrients and predict the potential environmental problems. The zinc isotope technique is of particular interest in interpreting soil processes. In this study, Zn isotopic data of soil samples in five profiles based on different land uses were provided, and Zn behavior in different soils was discussed. The isotopic ratios of soil samples in the abandoned orchard, secondary forest, abandoned cropland, and cropland are similar, with the δ 66 Zn varying from 0.15 to 0.29‰. However, the samples in shrub grassland show a lower δ 66 Zn of 0-0.20‰, which may be affected by anthropogenic sources. For the vertical patterns, the non-cultivated long-rooted plants (i.e., abandoned orchard and secondary forest) show no significant difference in the distribution of δ 66 Zn, but the patterns of cropland and abandoned cropland samples are reversed. The cropland samples show positive correlations between δ 66 Zn and Fe 2 O 3 (R 2  = 0.90) and MnO (R 2  = 0.75), indicating that Fe and Mn oxides preferentially adsorb heavy Zn isotopes on the mineral surfaces. The high affinity between Zn and oxides indicated that the concentration of bio-available Zn in cropland soils was getting lower. As a result, the supplies of micronutrients may be deficient and urged from fertilizer. This study provides a better understanding of Zn cycling in agricultural systems and gives improvements in soil management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background/aim: Today, stable isotopes of zinc are actively used for diagnostic purposes in oncology. However, there is extremely limited data on the attempts to apply stable zinc isotopes in cancer therapy or about the molecular mechanisms of their effects on the biology of tumor cells. Therefore, in this in vitro research, we evaluated the cytotoxic activity of stable zinc isotope ( 64 Zn) enriched compounds against malignant cells and determined the mechanisms of their action., Materials and Methods: Malignant and non-malignant cells of different histogenesis were used as objects of the study. The effect of the Zn 64 aspartate, Zn 64 glutamate, and Zn 64 sulfate on cell viability in a comparative aspect was evaluated. Compounds containing 64 Zn stable isotope enriched to 99.2%. Western blot analysis was used to determine the expression level of apoptosis regulatory proteins., Results: Salts of 64 Zn with amino acids had the most significant cytotoxic effect on malignant cells. The studied tumor cells, and especially MB16 melanoma cells were the most sensitive to the cytotoxic effects of Zn 64 aspartate. Zn 64 aspartate showed more significant cytotoxic activity than Zn aspartate (with natural isotope distribution) in the studied cell models. Zn 64 aspartate induced caspase-dependent cell death in A-549 cells and the p53-mediated apoptosis in melanoma cells., Conclusion: Malignant cells were more sensitive to the cytotoxic effect of the Zn 64 aspartate than normal cells. An increase in the intracellular concentration of 64 Zn, and hence isotope mass balance changes, may lead to the suppression of the viability and proliferation of malignant cells. These results can become the basis for developing a new generation of anticancer drugs., (Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

In this paper, the optimal preparative conditions (current density, deposition temperature, calcination temperature) for the original electrochemical synthesis of ZnO-Zn coating on aluminum foil support (ZnAF) were examined and determined the application for the removal of methyl orange (MO). Optimal application conditions for removing MO (volume and concentration of a treated solution) were also determined. In the following, four immobilized ZnO/Fe 2 O 3 photocatalysts with different molar ratios of Zn to Fe (0.42, 0.84, 1.68, and 3.36) were synthesized via the chemical precipitation method on optimized electrochemically synthesized ZnAF support. Characterization studies of synthesized materials included SEM-EDS and Raman scattering analyses. The efficiency of these catalysts for MO removal in the presence/absence of simulated solar radiation (SSR) was investigated. The adsorption isotherms were investigated, and the results show that the adsorption data were best fitted with the Freundlich adsorption isotherm model. Assessment of the thermodynamic parameters showed that although the adsorption process was weakly endothermic over the range of temperatures studied, the relatively high entropy change gave an overall negative change in Gibbs free energy making the processes spontaneous. In the presence of SSR, the optimal molar ratio of Zn to Fe was determined to be 1.68. The possibility of potential reusing the catalyst was examined six times in a row. The possibility for multiple uses of suspension, which is used for immobilization, was also examined. It was also determined that the application of the 1.68Zn/Fe/ZnAF/H 2 O 2 /SSR system after the dye removal generates hydrogen at a rate of 186.5 μmol g -1 after 6 h. Furthermore, in the presence of SSR and using a suspended form of catalyst, the removal efficiency was 1.6 times higher than the efficiency achieved with immobilized ZnO/Fe 2 O 3 catalyst. Using the HPLC method for 1.68Zn/Fe/ZnAF/SSR system, five primary intermediates were found to be formed. The applicability of ZnO/Fe 2 O 3 /ZnAF for removal of other dyes was also examined., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Diet is a crucial trait of an animal's lifestyle and ecology. The trophic level of an organism indicates its functional position within an ecosystem and holds significance for its ecology and evolution. Here, we demonstrate the use of zinc isotopes (δ 66 Zn) to geochemically assess the trophic level in diverse extant and extinct sharks, including the Neogene megatooth shark (Otodus megalodon) and the great white shark (Carcharodon carcharias). We reveal that dietary δ 66 Zn signatures are preserved in fossil shark tooth enameloid over deep geologic time and are robust recorders of each species' trophic level. We observe significant δ 66 Zn differences among the Otodus and Carcharodon populations implying dietary shifts throughout the Neogene in both genera. Notably, Early Pliocene sympatric C. carcharias and O. megalodon appear to have occupied a similar mean trophic level, a finding that may hold clues to the extinction of the gigantic Neogene megatooth shark., (© 2022. The Author(s).)

A sensitive and reliable biomarker of zinc status has yet to be identified, but observational research suggests that the exchangeable zinc pool (EZP) size may be a possible biomarker. This randomized, placebo-controlled trial aimed to compare the change in EZP size from baseline to endline in 174 children who were preventatively supplemented with 10 mg of zinc as part of a multiple micronutrient power (MNP) or as a standalone dispersible tablet for 24 weeks versus a placebo powder. The effects of systemic inflammation on EZP size were also evaluated. Zinc stable isotopes were administered intravenously to children at baseline and endline, and the EZP was measured by the urine extrapolation method. A total of 156 children completed the study with the zinc dispersible tablet group having the greatest increase in EZP (14.1 mg) over 24 weeks when compared with the MNP group (6.8 mg) (p < 0.01) or placebo group (2.0 mg) (p < 0.001). Median EZP size was not different between children with normal or elevated serum inflammatory markers. EZP size was responsive to longitudinal zinc supplementation and reflected the expected difference in bioavailability for two forms of supplementation. The apparent absence of an effect of inflammation on EZP size may offer an advantage for use as a biomarker for group comparisons between different interventions.

Background: Some subspecies of Dichapetalum gelonioides are the only tropical woody zinc (Zn)-hyperaccumulator plants described so far and the first Zn hyperaccumulators identified to occur exclusively on non-Zn enriched 'normal' soils. The aim of this study was to investigate Zn cycling in the parent rock-soil-plant interface in the native habitats of hyperaccumulating Dichapetalum gelonioides subspecies (subsp. pilosum and subsp. sumatranum). We measured the Zn isotope ratios (δ 66 Zn) of Dichapetalum plant material, and associated soil and parent rock materials collected from Sabah (Malaysian Borneo)., Results: We found enrichment in heavy Zn isotopes in the topsoil (δ 66 Zn 0.13 ‰) relative to deep soil (δ 66 Zn -0.15 ‰) and bedrock (δ 66 Zn -0.90 ‰). This finding suggests that both weathering and organic matter influenced the Zn isotope pattern in the soil-plant system, with leaf litter cycling contributing significantly to enriched heavier Zn in topsoil. Within the plant, the roots were enriched in heavy Zn isotopes (δ 66 Zn ~ 0.60 ‰) compared to mature leaves (δ 66 Zn ~ 0.30 ‰), which suggests highly expressed membrane transporters in these Dichapetalum subspecies preferentially transporting lighter Zn isotopes during root-to-shoot translocation. The shoots, mature leaves and phloem tissues were enriched in heavy Zn isotopes (δ 66 Zn 0.34-0.70 ‰) relative to young leaves (δ 66 Zn 0.25 ‰). Thisindicates that phloem sources are enriched in heavy Zn isotopes relative to phloem sinks, likely because of apoplastic retention and compartmentalization in the Dichapetalum subspecies., Conclusions: The findings of this study reveal Zn cycling in the rock-soil-plant continuum within the natural habitat of Zn hyperaccumulating subspecies of Dichapetalum gelonioides from Malaysian Borneo. This study broadens our understanding of the role of a tropical woody Zn hyperaccumulator plant in local Zn cycling, and highlights the important role of leaf litter recycling in the topsoil Zn budget. Within the plant, phloem plays key role in Zn accumulation and redistribution during growth and development. This study provides an improved understanding of the fate and behaviour of Zn in hyperaccumulator soil-plant systems, and these insights may be applied in the biofortification of crops with Zn., (© 2021. The Author(s).)

In highly industrialized, densely populated parts of Central Europe, mobilization of legacy Zn pollution from forest ecosystems may negatively affect the quality of water resources. To test this hypothesis, we determined the 66 Zn/ 64 Zn isotope ratios of 15 Zn reservoirs and fluxes in an acidified, spruce die-back affected mountain-slope catchment in northern Czech Republic. The δ 66 Zn values of precipitation, organic horizon, and runoff were statistically indistinguishable. In contrast, δ 66 Zn values of bedrock orthogneiss and mineral soil were significantly different from δ 66 Zn values of runoff. The magnitude of within-site Zn isotope fractionations appeared to be relatively small. Despite the large potential source of Zn in bedrock, runoff exported mostly young pollutant Zn that had been temporarily stored in the organic horizon. This conclusion was corroborated by comparing Zn input-output mass balances in the polluted northern catchment and in a relatively unpolluted catchment situated 250 km to the south. Seven-times higher Zn export via runoff at the northern site was controlled by a combination of 10-times higher atmospheric Zn input and five-times higher DOC leaching, compared to the southern site. In industrial areas, atmospherically deposited Zn is leached from headwater catchments in a direct analogy to leaching of highly toxic pollutant Pb.

It has been herein presented that a microemulsion, known to be an effective and safe drug delivery system following intravenous administration, can be loaded with traces of [ 68 Ga]Ga-PSMA-617 without losing its properties or causing toxicity. Following tolerated IV injections the capability of the microemulsion in altering [ 68 Ga]Ga-PSMA-617 distribution was presented at 120 min post injection based on its ex vivo biodistribution results.

The contamination of coastal environments by metallurgical wastes involves multiple biogeochemical processes; accordingly, understanding metal behavior and risk evaluation of contaminated areas, such as Sepetiba Bay (Rio de Janeiro, Brazil), remains challenging. This study coupled Zn isotopic analyses with sequential extractions (BCR) to investigate the mechanisms of Zn transfer between legacy electroplating waste and the main environments in Sepetiba Bay. This metallurgical waste showed a light bulk isotopic signature (δ 66/64 Znbulk JMC  = +0.30 ± 0.01‰, 2 s, n = 3) that was not distinct from the lithogenic geochemical baseline, but was different from signature of mangrove sediment considered as anthropogenic end member (δ 66/64 Zn JMC  = +0.86 ± 0.15‰) in a previous isotopic study in this area. Zn isotopic compositions of sediment samples (ranging from +0.20 to +0.98‰) throughout the bay fit a mixing model involving multiple sources, consistent with previous studies. In the metallurgic zone, the exchangeable/carbonate fraction (ZnF1) exhibited high Zn concentrations (ZnF1 = 9840 μg g -1 ) and a heavy isotopic composition (δ 66/64 ZnF1 JMC  = +1.10 ± 0.01‰). This finding showed that, in some cases, the bulk isotopic signature of waste is not the most relevant criterion for evaluating trace metal dispersion in the environment. Indeed, based on the BCR, it was observed that part of the anthropogenic metallurgical Zn was redistributed from the exchangeable/carbonate fraction in the waste to the surrounding mangrove sediment. Then, this contaminated sediment with heavy δ 66/64 Zn values was exported to other coastal environments. In Sepetiba Bay, contaminated sediments revealed a large concentration of ZnF1 fraction (up to 400 μg g -1 ) with a heavy Zn isotopic signature. This signature also matched the Zn isotopic signature of oysters in Sepetiba Bay reported by other studies; hence, measurement of the isotopic exchangeable/carbonate fraction has important implications for tracing the transfer of anthropogenic Zn to biota., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Interactions between aqueous Zn and mineral surfaces can lead to notable Zn isotope fractionation that affects Zn source fingerprinting, which needs an atomic-level understanding. In this study, we demonstrate that Zn isotope fractionation (Δ 66 Zn sorbed-aqueous ) during Zn sorption onto γ-Al 2 O 3 depends on both pH and Zn concentration and ultimately correlates to surface coverage (Γ). At pH values of 6.0-6.5 and/or Zn concentrations of 0.1-0.2 mM, where Γ < 0.8 μmol m -2 , Δ 66 Zn sorbed-solution is 0.47 ± 0.03‰, whereas Δ 66 Zn sorbed-aqueous decreases to 0.02 ± 0.07‰ at pH values of 7.0-8.0 and Zn concentrations of 0.4-0.8 mM, with a high Γ ranging from 1.5 to 3.2 μmol m -2 . Using extended X-ray absorption fine structure (EXAFS) spectroscopy, we elucidated that a Zn-Al layered double hydroxide (LDH) with a Zn-O bond length of 2.06 Å forms at high surface coverage (1.5 < Γ < 3.2 μmol m -2 ). In contrast, at low surface coverage (Γ < 0.8 μmol m -2 ), the sorbed Zn occurs as a tetrahedrally coordinated inner-sphere surface complex with an average Zn-O interatomic distance of 1.98 Å. Such contrasts lead to an atomic level understanding of the strong links between isotope fractionation, local bonding structures (i.e., coordination and bond distances), and solution chemistry, which is crucial for more effective applications of stable metal isotopes as environmental tracers.

The biogeochemical cycling of zinc (Zn) is intimately coupled with organic carbon in the ocean. Based on an extensive new sedimentary Zn isotope record across Earth's history, we provide evidence for a fundamental shift in the marine Zn cycle ~800 million years ago. We discuss a wide range of potential drivers for this transition and propose that, within available constraints, a restructuring of marine ecosystems is the most parsimonious explanation for this shift. Using a global isotope mass balance approach, we show that a change in the organic Zn/C ratio is required to account for observed Zn isotope trends through time. Given the higher affinity of eukaryotes for Zn relative to prokaryotes, we suggest that a shift toward a more eukaryote-rich ecosystem could have provided a means of more efficiently sequestering organic-derived Zn. Despite the much earlier appearance of eukaryotes in the microfossil record (~1700 to 1600 million years ago), our data suggest a delayed rise to ecological prominence during the Neoproterozoic, consistent with the currently accepted organic biomarker records., (© 2018 John Wiley & Sons Ltd.)

A thorough understanding of spatial and temporal emission and immission patterns of air pollutants in urban areas is challenged by the low number of air-quality monitoring stations available. Plants are promising low-cost biomonitoring tools. However, source identification of the trace metals incorporated in plant tissues (i.e., natural vs anthropogenic) and the identification of the best plant to use remain fundamental challenges. To this end, Nerium oleander L. collected in the city of Zaragoza (NE Spain) has been investigated as a biomonitoring tool for assessing the spatial immission patterns of airborne metals (Pb, Cu, Cr, Ni, Ce, and Zn). N. oleander leaves were sampled at 118 locations across the city, including the city center, industrial hotspots, ring-roads, and outskirts. Metal concentrations were generally higher within a 4 km radius around the city center. Calculated enrichment factors relative to upper continental crust suggest an anthropogenic origin for Cr, Cu, Ni, Pb, and Zn. Zinc isotopes showed significant variability that likely reflects different pollution sources. Plants closer to industrial hotspots showed heavier isotopic compositions (δ 66 Zn Lyon up to +0.70‰), indicating significant contributions of fly ash particles, while those far away were isotopically light (up to -0.95‰), indicating significant contributions from exhaust emissions and flue gas. We suggest that this information is applied for improving the environmental and human risk assessment related to the exposure to air pollution in urban areas.

Diversity and biomass of aquatic insects decline in metal-rich aquatic environments, but the mechanisms by which insects from such environments cope with potentially toxic metal concentrations to survive through adulthood are less well understood. In this study, we measured Zn concentrations and isotopes in laboratory-reared diatoms and mayflies (Neocloeon triangulifer) from larval through adult stages. The larvae were fed Zn-enriched diatoms, and bio-concentrated Zn by a factor of 2.5-5 relative to the diatoms but maintained the same Zn-isotopic ratio. These results reflect the importance of dietary uptake and the greater rate of uptake relative to excretion or growth. Upon metamorphosis to subimago, Zn concentrations declined by >70%, but isotopically heavy Zn remained in the subimago bodies. We surmised that the loss of isotopically light Zn during metamorphosis was due to the loss of detoxified Zn and retention of metabolically useful Zn. Through the transition from subimago to imago, Zn concentrations and isotope ratios were virtually unchanged. Because the decrease in Zn body concentration and increase in heavier Zn are seen in the subimagos relative to the larvae, the compartmentalization of Zn must be occurring within the larvae. A biodynamic model was constructed, allowing for isotopic fractionation and partitioning of Zn between metabolically essential and detoxified Zn reservoirs within larvae. The model provides a consistent set of rate and fractionation constants that successfully describe the experimental observations. Specifically, metabolically essential Zn is isotopically heavier and is tightly held once assimilated, and excess, isotopically light Zn is sequestered, detoxified, and ultimately lost during the metamorphosis of larvae to subimagos. To our knowledge, this is the first documentation of in vivo isotopic fractionation in insects, offering an improved understanding of the mechanisms and rates by which the N. triangulifer larvae regulate excess Zn in their bodies., (Published by Elsevier B.V.)

Here we use two enriched stable isotopes, 68 Zn en and 64 Zn en (>99%), to prepare 68 ZnO nanoparticles (NPs) and soluble 64 ZnCl 2 . The standard LUFA 2.2 test soil was dosed with 68 ZnO NPs and soluble 64 ZnCl 2 to 5 mg kg -1 each, plus between 0 and 95 mg kg -1 of soluble ZnCl 2 with a natural isotope composition. After 0, 1, 3, 6, and 12 months of soil incubation, earthworms (Eisenia andrei) were introduced for 72 h exposures. Analyses of soils, pore waters, and earthworm tissues using multiple collector inductively coupled plasma mass spectrometry allowed the simultaneous measurement of the diagnostic 68 Zn/ 66 Zn, 64 Zn/ 66 Zn, and 68 Zn/ 64 Zn ratios, from which the three different isotopic forms of Zn were quantified. Eisenia andrei was able to regulate Zn body concentrations with no difference observed between the different total dosing concentrations. The accumulation of labeled Zn by the earthworms showed a direct relationship with the proportion of labeled to total Zn in the pore water, which increased with longer soil incubation times and decreasing soil pH. The 68 Zn en / 64 Zn en ratios determined for earthworms (1.09 ± 0.04), soils (1.09 ± 0.02), and pore waters (1.08 ± 0.02) indicate indistinguishable environmental distribution and uptake of the Zn forms, most likely due to rapid dissolution of the ZnO NPs.

Objective: To determine the dietary zinc absorption in a Chinese elderly population and provide the basic data for the setting of zinc (Zn) recommended nutrient intakes (RNI) for Chinese elderly people., Methods: A total of 24 elderly people were recruited for this study and were administered oral doses of 3 mg 67Zn and 1.2 mg dysprosium on the fourth day. The primary macronutrients, energy, and phytic acid in the representative diet were examined based on the Chinese National Standard Methods. Fecal samples were collected during the experimental period and analyzed for zinc content, 67Zn isotope ratio, and dysprosium content., Results: The mean (± SD) zinc intake from the representative Chinese diet was 10.6 ± 1.5 mg/d. The phytic acid-to-zinc molar ratio in the diet was 6.4. The absorption rate of 67Zn was 27.9% ± 9.2%. The RNI of zinc, which were calculated by the absorption rate in elderly men and women, were 10.4 and 9.2 mg/d, respectively., Conclusion: This study got the dietary Zn absorption in a Chinese elderly population. We found that Zn absorption was higher in elderly men than in elderly women. The current RNI in elderly female is lower than our finding, which indicates that more attention is needed regarding elderly females' zinc status and health., (Copyright © 2017 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.)

Background: Zinc deficiency and contaminated water are major contributors to diarrhea in developing countries. Food fortification with zinc has not shown clear benefits, possibly because of low zinc absorption from inhibitory food matrices. We used a novel point-of-use water ultrafiltration device configured with glass zinc plates to produce zinc-fortified, potable water., Objective: The objective was to determine zinc bioavailability from filtered water and the efficacy of zinc-fortified water in improving zinc status., Design: In a crossover balanced study, we measured fractional zinc absorption (FAZ) from the zinc-fortified water in 18 healthy Swiss adults using zinc stable isotopes and compared it with zinc-fortified maize porridge. We conducted a 20-wk double-blind randomized controlled trial (RCT) in 277 Beninese school children from rural settings who were randomly assigned to receive a daily portion of zinc-fortified filtered water delivering 2.8 mg Zn (Zn+filter), nonfortified filtered water (Filter), or nonfortified nonfiltered water (Pump) from the local improved supply, acting as the control group. The main outcome was plasma zinc concentration (PZn), and the 3 groups were compared by using mixed-effects models. Secondary outcomes were prevalence of zinc deficiency, diarrhea prevalence, and growth., Results: Geometric mean (-SD, +SD) FAZ was 7-fold higher from fortified water (65.9%; 42.2, 102.4) than from fortified maize (9.1%; 6.0, 13.7; P < 0.001). In the RCT, a significant time-by-treatment effect on PZn (P = 0.026) and on zinc deficiency (P = 0.032) was found; PZn in the Zn+filter group was significantly higher than in the Filter (P = 0.006) and Pump (P = 0.025) groups. We detected no effect on diarrhea or growth, but our study did not have the duration and power to detect such effects., Conclusions: Consumption of filtered water fortified with a low dose of highly bioavailable zinc is an effective intervention in children from rural African settings. Large community-based trials are needed to assess the effectiveness of zinc-fortified filtered water on diarrhea and growth. These trials were registered at clinicaltrials.gov as NCT01636583 and NCT01790321., (© 2015 American Society for Nutrition.)

Zinc (Zn) is essential for development, growth, and reproduction. The Mexican government subsidizes micronutrient-fortified milk for risk groups, with positive effect on the targeted groups' plasma Zn level, inferring a good absorption is achieved although it has not being measured. The aim of this study was to determine the impact of micronutrient-fortified milk intake during 27 days on Zn absorption in adolescent girls from northwest Mexico. Therefore, Zn absorption was evaluated in 14 healthy adolescent girls (14.1 years old) with adequate plasma Zn levels, before and after 27 days of fortified Zn milk intake. Fractional Zn absorption (FZA) was calculated from urinary ratios of stable isotopic Zn tracers administered orally and intravenously on days 0 and 27, and total absorbed Zn (TZA) was calculated. At the beginning, Zn intake was 6.8 ± 0.85 mg/d (mean ± SE), and 50 % of the adolescent girls did not achieve their requirement (7.3 mg/d). Additionally, FZA was negatively correlated with Zn intake (r =-0.61, p = 0.02), while TZA (1.06 mg/d) was insufficient to cover the physiologic requirements of adolescent girls (3.02 mg/d). At the end of the intervention, all the girls reached the Zn intake recommendation and TZA, 3.09 mg/d, which was enough to meet the physiological requirement for 57 % of the adolescent girls. Therefore, the low Zn intake and the Zn status of adolescent girls were positively impacted by Zn-fortified milk intake and its good absorption rate.

NaFeEDTA has been applied in many foods as an iron fortificant and is used to prevent iron deficiency in Fe-depleted populations. In China, soy sauce is fortified with NaFeEDTA to control iron deficiency. However, it is unclear whether Fe-fortified soy sauce affects zinc absorption. To investigate whether NaFeEDTA-fortified soy sauce affects zinc absorption in children, sixty children were enrolled in this study and randomly assigned to three groups (10 male children and 10 female children in each group). All children received daily 3 mg of (67)Zn and 1.2 mg of dysprosium orally, while the children in the three groups were supplemented with NaFeEDTA-fortified soy sauce (6 mg Fe, NaFeEDTA group), FeSO₄-fortified soy sauce (6 mg Fe, FeSO₄ group), and no iron-fortified soy sauce (control group), respectively. Fecal samples were collected during the experimental period and analyzed for the Zn content, (67)Zn isotope ratio and dysprosium content. The Fe intake from NaFeEDTA-fortified and FeSO₄-fortified groups was significantly higher than that in the control group (P < 0.0001). The daily total Zn intake was not significantly different among the three groups. There were no significant differences in fractional Zn absorption (FZA) (P = 0.3895), dysprosium recovery (P = 0.7498) and Zn absorption (P = 0.5940) among the three groups. Therefore, NaFeEDTA-fortified soy sauce does not affect Zn bioavailability in children.

Zinc oxide nanoparticles (ZnO NPs) exhibit novel physiochemical properties and have found increasing use in sunscreen products and cosmetics. The potential toxicity is of increasing concern due to their close association with human skin. A time-of-flight secondary ion mass spectrometry (TOF-SIMS) and confocal laser scanning microscopy (CLSM) imaging method was developed and validated for rapid and sensitive cytotoxicity study of ZnO NPs using human skin equivalent HaCaT cells as a model system. Assorted material, chemical, and toxicological analysis methods were used to confirm their shape, size, crystalline structure, and aggregation properties as well as dissolution behavior and effect on HaCaT cell viability in the presence of various concentrations of ZnO NPs in aqueous media. Comparative and correlative analyses of aforementioned results with TOF-SIMS and CLSM imaging results exhibit reasonable and acceptable outcome. A marked drop in survival rate was observed with 50μg/ml ZnO NPs. The CLSM images reveal the absorption and localization of ZnO NPs in cytoplasm and nuclei. The TOF-SIMS images demonstrate elevated levels of intracellular ZnO concentration and associated Zn concentration-dependent (40)Ca/(39)K ratio, presumably caused by the dissolution behavior of ZnO NPs. Additional validation by using stable isotope-labeled (68)ZnO NPs as tracers under the same experimental conditions yields similar cytotoxicity effect. The imaging results demonstrate spatially-resolved cytotoxicity relationship between intracellular ZnO NPs, (40)Ca/(39)K ratio, phosphocholine fragments, and glutathione fragments. The trend of change in TOF-SIMS spectra and images of ZnO NPs treated HaCaT cells demonstrate the possible mode of actions by ZnO NP involves cell membrane disruption, cytotoxic response, and ROS mediated apoptosis., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Stable Zn isotopes are increasingly used to trace the source of metal pollution in the environment and to gain a better understanding of the biogeochemical cycle of Zn. In this work, we investigated the effect of plants on Zn isotope fractionation in the soil-plant system of the surface horizon of two Zn-rich Technosols (pH 6.73-7.51, total Zn concentration = 9470-56600 mg kg(-1)). In a column experiment, the presence of Agrostis capillaris L. significantly increased the mobilization of Zn from soil to leachate, predominantly as a result of root-induced soil acidification. The zinc isotope compositions of plants and leachates indicated that the Zn uptake by A. capillaris did not fractionate Zn isotopes as compared to the leachates. Within the plant, heavier Zn isotopes were preferentially retained in roots (Δ66Znroot - shoot=+0.24 to +0.40 ‰). More importantly, the Zn released in leachates due to root-induced mobilization was isotopically heavier than the Zn released in the absence of plants (Δ66Zn=+0.16 to +0.18 ‰). This indicates that the rhizosphere activity of A. capillaris mobilized Zn from another pool than the one that spontaneously releases Zn upon contact with the percolating solution. Mobilization of Zn by the roots might thus exert a stronger influence on the Zn isotope composition in the soil solution than the Zn uptake by the plant. This study highlights the key role of the rhizosphere activity in Zn release in soil and demonstrates that stable Zn isotopes provide a useful proxy for the detection of Zn mobilization in soil-plant systems.

In this study, we assessed past and present influence of ancient mining activity on metal(loid) enrichment in sediments of a former mining watershed (Gardon River, SE France), that is now industrialized and urbanized. A sedimentary archive and current sediments were characterized combining geochemical analyses, zinc isotopic analyses and sequential extractions. The archive was used to establish local geochemical background and recorded (i) increasing enrichment factors (EFs) for Pb, Zn, Cd, Tl, Hg, As and Sb throughout the industrial era, (ii) a contamination peak in 1976 attributed to a tailings dam failure, and (iii) current levels in 2002 and 2011 similar to those of 1969, except for Sb and Hg, reflecting a persisting contamination pattern. Inter-element relationships and spatial distribution of EF values of current sediments throughout the watershed suggested that both ancient and current contamination had a common origin for Pb, Zn, Cd, Tl and As related to the exploitation of Pb/Zn mineralization while old Sb mines and coal extraction area were the main sources for Sb and Hg respectively. This prevailing mining origin was reflected for Zn by a relatively uniform isotopic composition at δ(66)Zn=0.23 ± 0.03‰, although slight decrease from 0.23‰ to 0.18‰ was recorded from upstream to downstream sites along the river course in relation with the contribution of the lighter δ(66)Zn signature (~0.08‰) of acid mine drainage impacted tributaries. Results from sequential extractions revealed that the potential mobility of the studied metal(loid)s varied in the order Sb

Magnetic isotope and magnetic field effects on the rate of DNA synthesis catalysed by polymerases β with isotopic ions (24)Mg(2+), (25)Mg(2+) and (26)Mg(2+) in the catalytic sites were detected. No difference in enzymatic activity was found between polymerases β carrying (24)Mg(2+) and (26)Mg(2+) ions with spinless, non-magnetic nuclei (24)Mg and (26)Mg. However, (25)Mg(2+) ions with magnetic nucleus (25)Mg were shown to suppress enzymatic activity by two to three times with respect to the enzymatic activity of polymerases β with (24)Mg(2+) and (26)Mg(2+) ions. Such an isotopic dependence directly indicates that in the DNA synthesis magnetic mass-independent isotope effect functions. Similar effect is exhibited by polymerases β with Zn(2+) ions carrying magnetic (67)Zn and non-magnetic (64)Zn nuclei, respectively. A new, ion-radical mechanism of the DNA synthesis is suggested to explain these effects. Magnetic field dependence of the magnesium-catalysed DNA synthesis is in a perfect agreement with the proposed ion-radical mechanism. It is pointed out that the magnetic isotope and magnetic field effects may be used for medicinal purposes (trans-cranial magnetic treatment of cognitive deceases, cell proliferation, control of the cancer cells, etc).

Assessing the bioavailability of non-heme iron and zinc is essential for recommending diets that meet the increased growth-related demand for these nutrients. We studied the bioavailability of iron and zinc from a rice-based meal in 16 adolescent boys and girls, 13-15 y of age, from 2 government-run residential schools. Participants were given a standardized rice meal (regular) and the same meal with 100 g of guava fruit (modified) with (57)Fe on 2 consecutive days. A single oral dose of (58)Fe in orange juice was given at a separate time as a reference dose. Zinc absorption was assessed by using (70)Zn, administered intravenously, and (67)Zn given orally with meals. The mean hemoglobin concentration was similar in girls (129 ± 7.8 g/L) and boys (126 ± 7.1 g/L). There were no sex differences in the indicators of iron and zinc status except for a higher hepcidin concentration in boys (P < 0.05). The regular and modified meals were similar in total iron (10-13 mg/meal) and zinc (2.7 mg/meal) content. The molar ratio of iron to phytic acid was >1:1, but the modified diet had 20 times greater ascorbic acid content. The absorption of (57)Fe from the modified meal, compared with regular meal, was significantly (P < 0.05) greater in both girls (23.9 ± 11.2 vs. 9.7 ± 6.5%) and boys (19.2 ± 8.4 vs. 8.6 ± 4.1%). Fractional zinc absorption was similar between the regular and modified meals in both sexes. Hepcidin was found to be a significant predictor of iron absorption (standardized β = -0.63, P = 0.001, R(2) = 0.40) from the reference dose. There was no significant effect of sex on iron and zinc bioavailability from meals. We conclude that simultaneous ingestion of guava fruit with a habitual rice-based meal enhances iron bioavailability in adolescents.

Sedum alfredii is one of a few species known to hyperaccumulate zinc (Zn) and cadmium (Cd). Xylem transport and phloem remobilization of Zn in hyperaccumulating (HP) and nonhyperaccumulating (NHP) populations of S. alfredii were compared. Micro-X-ray fluorescence (μ-XRF) images of Zn in the roots of the two S. alfredii populations suggested an efficient xylem loading of Zn in HP S. alfredii, confirmed by the seven-fold higher Zn concentrations detected in the xylem sap collected from HP, when compared with NHP, populations. Zn was predominantly transported as aqueous Zn (> 55.9%), with the remaining proportion (36.7-42.3%) associated with the predominant organic acid, citric acid, in the xylem sap of HP S. alfredii. The stable isotope (68)Zn was used to trace Zn remobilization from mature leaves to new growing leaves for both populations. Remobilization of (68)Zn was seven-fold higher in HP than in NHP S. alfredii. Subsequent analysis by μ-XRF, combined with LA-ICPMS (laser ablation-inductively coupled plasma mass spectrometry), confirmed the enhanced ability of HP S. alfredii to remobilize Zn and to preferentially distribute the metal to mesophyll cells surrounding phloem in the new leaves. The results suggest that Zn hyperaccumulation by HP S. alfredii is largely associated with enhanced xylem transport and phloem remobilization of the metal. To our knowledge, this report is the first to reveal enhanced remobilization of metal by phloem transport in hyperaccumulators., (© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.)

Stable Zn isotopes are fractionated in roots and leaves of plants. Analyses demonstrate that the heavy Zn isotopes are enriched in the root system of plants with respect to shoots and leaves as well as the host soil, but the fractionation mechanisms remain unclear. Here we show that the origin of this isotope fractionation is due to a chemical isotope effect upon complexation by Zn malates and citrates in the aerial parts and by phosphates in the roots. We calculated the Zn isotope effect in aqueous citrates, malates, and phosphates by ab initio methods. For pH<5, the Zn isotopic compositions of the various parts of the plants are expected to be similar to those of groundwater. In the neutral to alkaline region, the calculations correctly predict that (66)Zn is enriched over (64)Zn in roots, which concentrate phosphates, with respect to leaves, which concentrate malates and citrates, by about one permil. It is proposed that Zn isotope fractionation represents a useful tracer of Zn availability and mobility in soils.

The variety of physiologic and biologic functions of zinc is expected to enable the development of zinc-related medicines. In this study, the distribution of endogenous zinc, the disposition after intravenous injection, and the intestinal absorption of zinc were investigated in vivo using rats from the viewpoints of pharmaceutical science and pharmacokinetics. High levels of endogenous zinc were observed in bone, testis, and liver. RT-PCR analysis on the mRNA of metallothionein in tissues clarified that it is significantly correlated with the distribution of zinc, suggesting that zinc is accumulated in tissues as a complex with MT. Following intravenous injection, uptake of zinc was high in liver, spleen, pancreas, kidney, and intestine. Fractional absorptions of zinc after oral administration to fasted rats were greater than those to fed rats, suggesting that some factors in diet inhibit the absorption of zinc. In fasted rats, fractional absorption was slightly decreased in high-dose group, suggesting the involvement of carrier-mediated transport. Study utilizing an in situ closed-loop method also indicated saturable intestinal absorption of zinc. These findings will further the research and development of zinc-related medicines by providing basic and important information on zinc., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Zinc-phosphite and -phosphate based microporous materials are crystalline open framework materials with potential industrial applications. Although (31)P MAS NMR has been used for characterization of these materials, the local environments around zinc centres have never been directly probed by solid-state NMR due to the many unfavourable NMR characteristics of (67)Zn. In this work, we have characterized the local structure around the Zn centres in several representative microporous zinc phosphites and zinc phosphates by acquiring natural abundance (67)Zn solid-state NMR spectra at ultrahigh magnetic field of 21.1 T. The observed line-shapes are mainly determined by the second order quadrupolar interaction. The NMR tensor parameters were extracted from the spectra and are related to the local geometry around the Zn centre. Computational study of the electric field gradient (EFG) tensor at Zn was performed using hybrid density functional theory (DFT) calculations at B3LYP level of theory on model clusters. The calculations using Projector Augmented-Wave (PAW) method were also carried out with the CASTEP code wherever it was possible. The work has shown that it is possible to study Zn environments in porous materials which often have very low Zn concentration by natural abundance (67)Zn SSNMR at very high magnetic fields.

Background: Celiac disease (CD) is an immunologic enteropathy triggered by the intake of gluten. It is thought that the enteropathy impairs gut function and absorption., Objective: We assessed the zinc-absorption capacity and small-bowel integrity in children with CD., Design: Children in whom a diagnosis of CD was considered clinically and either confirmed (n = 16; Marsh score ≥3) or not (n = 22; Marsh score of 0) with a small-bowel biopsy (SBB) were recruited. The fractional absorption of zinc (FAZ) was determined by the administration of an oral (67)Zn dose (2.5 mg) and an intravenous (70)Zn dose (0.2 mg) 2 h before and during the SBB, respectively. Spot urine samples were collected, and zinc isotopic ratios were determined by ion-coupled plasma mass spectrometry. Gut health was assessed by the ingestion of (13)C-sucrose (20 g) after an overnight fast, and breath samples were collected and analyzed by isotope ratio mass spectrometry., Results: There was no difference in FAZ between children with a Marsh score ≥3 (mean ± SEM: 0.68 ± 0.05) and children with a Marsh score of 0 (0.74 ± 0.05). The exchangeable zinc pool (EZP) was significantly (P < 0.05) lower in children with a Marsh score ≥3 (2.6 ± 0.8 mg/kg) than in children with a Marsh score of 0 (3.8 ± 1.4 mg/kg). Gut function in children with a Marsh score ≥3 (4.5 ± 0.7% cumulative dose recovered at 90 min) was lower than the lower cutoff of a normal gut-function breath test (5.06% cumulative dose recovered at 90 min) but not significantly different from that in children with a Marsh score of 0 (4.9 ± 0.4%). There was a significant (P < 0.01) correlation between zinc absorption and gut function in children with CD., Conclusions: Zinc absorption did not appear below usual amounts in subjects with CD. Children with CD have impaired gut function that may affect their zinc nutritional status as shown by a smaller EZP. However, the EZP decrease in children with CD was not compared with that in healthy control subjects, and its biological meaning is uncertain.

Zinc (Zn) deficiency has been recognized as a potential risk for human health in many developing regions where staple food with low micronutrient density represents a major proportion of the diet. The success of strategies to increase Zn content in the edible part of crops requires better understanding of Zn transport to, and distribution within, the grains. The transfer of Zn from the growth medium to wheat (Triticum aestivum) grains in an ear culture system was investigated by using the stable Zn isotope (70) Zn, and the spatial distribution of Zn within the grains was studied by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Zinc was readily transported in the stem up to the rachis. More Zn accumulated in the stem when higher amounts of Zn were supplied to the medium. Once Zn was transported into the grain, Zn accumulated particularly in the crease vascular tissue. The gradient of (70) Zn concentration between crease vascular tissue, aleurone layer and endosperm demonstrates that Zn is distributed within grain through the crease phloem. These results suggest that two barriers of Zn transport into wheat grains may exist: between the stem tissue rachis and the grain, and the maternal and filial tissues in the grain., (© The Authors (2010). Journal compilation © New Phytologist Trust (2010).)

Metal oxide nanoparticles are commonly used in personal-care formulations as protective agents against exposure to ultraviolet radiation. Although previous research has concluded that nanoparticles do not penetrate healthy skin, it remains contentious whether this conclusion holds under normal conditions of sunscreen use. Humans (n = 20) were exposed to sunscreens containing zinc oxide (ZnO) particles to determine if Zn from the particles was absorbed through skin over five consecutive days under outdoor conditions. Two sunscreens were tested-"nano sunscreen" containing 19-nm nanoparticles and "bulk sunscreen" containing > 100-nm particles. Venous blood and urine samples were collected 8 days before exposure, twice daily during the trial, and 6 days post-exposure. As the first application in nanotechnology studies, stable isotope tracing was used where the ZnO, enriched to > 99% with the stable isotope (68)Zn, allowed dermally absorbed zinc to be distinguished from naturally occurring zinc. The overwhelming majority of applied (68)Zn was not absorbed, although blood and urine samples from all subjects exhibited small increases in levels of tracer (68)Zn. The amount of tracer detected in blood after the 5-day application period was ∼1/1000 th that of total Zn in the blood compartment. Tracer levels in blood continued to increase beyond the 5-day application phase in contrast to those in urine. Levels of (68)Zn in blood and urine from females receiving the nano sunscreen appeared to be higher than males receiving the same treatment and higher than all subjects receiving the bulk sunscreen. It is not known whether (68)Zn has been absorbed as ZnO particles or soluble Zn or both.

We determined the true absorption and endogenous fecal loss of zinc (Zn) in goats using its stable isotope. Three goats were fed with the diet containing 50 mg/kg Zn twice a day for 17 days. In the morning of day 11, the goats were given a meal labeled by (67) Zn as the tracer with dysprosium as the unabsorbed marker. Then the goats were given unlabeled diet as the rest of the morning feed. We measured dietary and fecal Zn concentration, (67) Zn abundance and dysprosium concentration in feces. The excretion pattern of the tracer Zn into feces differed from that of dysprosium. Therefore, we directly calculated the true absorption of Zn from Zn concentration and (67) Zn abundance in fecal samples collected after the labeled diet was given. The apparent absorption of Zn was -0.009 ± 0.016 mg/kg bodyweight (fractional absorption, -1.07 ± 1.85%). The true absorption of Zn was 0.162 ± 0.018 mg/kg bodyweight (fractional absorption, 18.25 ± 2.01%). The endogenous fecal loss of Zn was 0.172 ± 0.004 mg/kg bodyweight and the intestinal secretion of Zn was 0.210 ± 0.009 mg/kg bodyweight. The present experiment indicates that stable isotopic Zn is a powerful tool for examining Zn metabolism in ruminants., (© 2010 The Authors; Journal compilation © 2010 Japanese Society of Animal Science.)

We report the results of our solid-state (67)Zn NMR study of the various zinc sites in four zinc-amino acid coordination complexes: bis(glycinato)zinc(II) monohydrate; bis(l-alaninato)zinc(II); bis(l-histidinato)zinc(II) dihydrate; and sodium bis(l-cysteinato)zincate(II) hexahydrate; as well as a related complex, bis(imidazole)zinc(II) chloride. We demonstrate the advantages of using high (21.1 T) applied magnetic fields for detecting (67)Zn directly at ambient temperatures using the quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) pulse sequence. The stepped-frequency technique was employed in cases where the central-transition (CT) (67)Zn NMR spectra were too broad to be uniformly excited. The parameters of the anisotropic zinc tensors were extracted by iterative simulations of the experimental spectra. In all cases, the quadrupolar interaction is found to dominate the central-transition (67)Zn NMR spectra; no convincing effects from chemical shift anisotropy (CSA) on the NMR spectra of the five complexes could be reliably detected at this field strength. Analyses of the experimental NMR spectra reveal that the (67)Zn quadrupolar coupling constants (C(Q)) range from 7.05 to 26.4 MHz, the isotropic chemical shifts (delta(iso)) range from 140 to 265 ppm, and the quadrupolar asymmetry parameters (eta(Q)) range from 0.20 to 0.95. The first report of the NMR spectral features of pentacoordinated zinc sites is included for two complexes. Quantum chemical calculations of the electric field gradient (EFG) and magnetic shielding tensors reproduced the experimental results to a reasonable extent. Moreover, the computationally determined orientations of both tensors permit correlations between NMR tensor properties and zinc local environments to be understood.

Biofortification of crops that provide major food staples to large, poor rural populations offers an appealing strategy for diminishing public health problems attributable to micronutrient deficiencies. The objective of this first-stage human study was to determine the increase in quantity of zinc (Zn) absorbed achieved by biofortifying wheat with Zn. Secondary objectives included evaluating the magnitude of the measured increases in Zn absorption as a function of dietary Zn and phytate. The biofortified and control wheats were extracted at high (95%) and moderate (80%) levels and Zn and phytate concentrations measured. Adult women with habitual diets high in phytate consumed 300 g of 95 or 80% extracted wheat as tortillas for 2 consecutive days using either biofortified (41 mg Zn/g) or control (24 mg Zn/g) wheat. All meals for the 2-d experiment were extrinsically labeled with Zn stable isotopes and fractional absorption of Zn determined by a dual isotope tracer ratio technique. Zn intake from the biofortified wheat diet was 5.7 mg/d (72%) higher at 95% extraction (P < 0.001) and 2.7 mg/d (68%) higher at 80% extraction compared with the corresponding control wheat (P = 0.007). Zn absorption from biofortified wheat meals was (mean +/- SD) 2.1 +/- 0.7 and 2.0 +/- 0.4 mg/d for 95 and 80% extraction, respectively, both of which were 0.5 mg/d higher than for the corresponding control wheat (P < 0.05). Results were consistent with those predicted by a trivariate model of Zn absorption as a function of dietary Zn and phytate. Potentially valuable increases in Zn absorption can be achieved from biofortification of wheat with Zn.

Common beans contain relatively high concentrations of iron (Fe) and zinc (Zn) but are also high in polyphenols and phytates, factors that may inhibit Fe and Zn absorption. In vitro (Caco-2 cells) and in vivo (pigs) models were used to compare Fe and Zn bioavailabilities between red and white beans, which differ in polyphenol content. Bean/maize diets containing 37% of either white or red cooked beans were formulated. Fe uptake by Caco-2 cells was 14-fold higher from the white bean diet compared to the red bean diet. The diets were fed to anemic piglets (n = 10) for 35 days. On experiment days 7 and 21, pigs were given meals containing beans intrinsically labeled with stable isotopes of Fe and Zn ((58)Fe, (70)Zn), followed by intravenous (iv) injections of (54)Fe and (67)Zn, to assess Fe and Zn absorption. Isotope ratios determined by inductively coupled plasma mass spectrometry in whole blood and plasma samples were used to calculate iron and zinc absorption, respectively. On day 35, animals were killed and duodenal sections were collected for DMT1 gene expression analysis. Fe absorption was 14 and 16% from the first labeled meal and 9 and 10.5% from the second labeled meal for the white and red beans, respectively (P > 0.05). Zn absorption was 28 and 23% from the first meal (P > 0.05) and 31 and 29% from the second meal (P > 0.05) for the white and red beans, respectively. DMT1 gene expression did not differ between treatments. It was concluded that bean color does not affect Fe or Zn bioavailability in vivo and that beans are a good source of bioavailable Fe and Zn.

Background: Iron supplements are commonly recommended for infants but were suggested to inhibit zinc and copper absorption., Objective: The objective of this study was to investigate potential effects of iron supplementation, infant age, and mineral status on zinc and copper absorption in infants at 6 and 9 mo of age., Design: Twenty-five healthy breastfed term infants were recruited from a larger randomized iron supplementation trial. Six of these infants received iron supplements (1 mg . kg(-1) . d(-1)) from 4 to 9 mo, 8 were supplemented from 6 to 9 mo, and 11 received placebo only. Zinc and copper absorption was measured at 6 and 9 mo of age, using orally administered (70)Zn and (65)Cu and fecal monitoring of recovered stable isotopes., Results: Mean (+/-SD) zinc absorption was 51.9 +/- 17.9%, and mean copper absorption was 79.0 +/- 13.5%. No significant difference was observed in zinc or copper absorption between 6 and 9 mo of age. When combining all measurements, no significant effect of prior iron supplementation was observed on zinc or copper absorption. No significant correlation was observed between plasma zinc and zinc absorption or between plasma copper and copper absorption. No significant correlation was observed between erythrocyte copper-zinc-dependent superoxide dismutase activity and copper absorption., Conclusions: The study does not support the contention that iron supplements inhibit the absorption of zinc or copper in healthy breastfed infants at 6-9 mo of age. In addition, we did not find any age-related changes in zinc or copper absorption between 6 and 9 mo of age.

One of the paradigms of Zn2+ metallobiochemistry is that coordination of water to Zn2+ provides a mechanism of activation that involves lowering the pKa by approximately 7 pH units. This idea has become central to the development of mechanisms of action for zinc metalloproteins. However, the direct measurement of the pKa of water bound to Zn2+ in a metalloprotein has yet to be accomplished. Developing models for Zn2+-OH2 species has been a significant challenge, but we have utilized solid-state 67Zn NMR spectroscopy as a means to characterize one of the few examples of water bound to mononuclear tetrahedral Zn2+: ([Tp(But,Me)]Zn(OH2))[HOB(C6F5)3]. The measured quadrupole coupling (Cq) constant is 4.3 MHz with an asymmetry parameter of etaq of 0.6. Likewise, due to the small value of Cq, anisotropic shielding also contributed to the observed 67Zn NMR lineshape. As expected, the computed values of the magnetic resonance parameters depend critically on the nature of the anion. The predicted value of Cq for ([Tp(But,Me)]Zn(OH2))[HOB(C6F5)3] is -4.88 MHz. We discuss the results of these calculations in terms of the nature of the anion, the local electrostatics, and its subsequent hydrogen bonding to [Tp(But,Me)]Zn(OH2)+.