Zinc Enrichment Research Articles

Iron Age and Roman metallurgical activities at the Spasovine placer tin deposit, West Serbia

Spasovine, on the south flank of Mt. Cer in West Serbia, is one of the rare localities where Late Bronze Age placer tin mining activities have been documented. Archeological pedestrian surveys on this river terrace recovered ceramic fragments with metal-rich coatings, thought to be fragments of technical ceramics. The physical characteristics of the “petrol” gray-bodied ceramics are consistent with Roman Period ca. 200-300AD production, while black-bodied sherds are most consistent with Iron Age ceramics of western Serbia. SEM-EDS analysis of polished thin-sections and rough surfaces has shown that the fragments are enriched in various metallic residues (Zn, Sn, Cu, Pb in various combinations). Of the fourteen sherds studied, nine Roman samples contain Zn-rich coatings on the inner surfaces as well as deeper penetration of zinc enrichment into the ceramic interior, consistent with Zn cementation for brass. Three of these also contained younger addition of Sn, indicating that they were repurposed for bronze production at Spasovine. The prehistoric sherds contain tin along with Cu and Pb, consistent with the production of leaded tin bronze, which is not known from the area until the Iron Age (ca. 800-600BC). Thus, Spasovine was the site of itinerant mining and metallurgical activity, at least sporadically, over a period of 1700 years from the Late Bronze Age (14th century BCE) to the Roman Period (2nd-3rd century CE). This demonstrates that small deposits of placer tin could have had long-term impact on regional tin economies in ancient Europe.

Bioremediation of a saline-alkali soil polluted with Zn using ryegrass associated with Fusariumincarnatum

Biotechnological strategies have become effective in the remediation of polluted soils as they are cost-effective and do not present a risk of secondary pollution. However, using a single bioremediation technique (microorganism or plant) is not suitable for achieving a high remediation rate of polluted saline-alkali soils with heavy metals. Therefore, the present study aims to assess the effects and mechanisms of combined ryegrass and Fusarium incarnatum on the zinc (Zn)-polluted saline-alkali soil over 45 days. According to the obtained results, the combined Fusarium incarnatum-ryegrass showed the highest remediation rate of 49.35% after 45 days, resulting in a significantly lower soil Zn concentration than that observed in the control group. In addition, the inoculation of Fusarium incarnatum showed a positive effect on the soil EPS secretion. The soil protein contents ranged from 0.035 to 0.055 mg/kg, while the soil polysaccharide contents increased from 0.25 to 0.61 mg/g. The soil microbial flora and ryegrass showed resistance to saline and alkaline stresses through the secretion of extracellular polysaccharides. The three-dimensional fluorescence spectrum (3D-EEM) confirmed that EPS in the soil was mainly a fulvic acid-like substance. The fluorescein diacetate (FDA) hydrolase activity in the saline-alkali soil was first increased due to the effect of Fusarium incarnatum and then decreased to a minimum value of 96 μg/(g·h). In addition, the Fusarium incarnatum inoculation improved the diversity and richness of soil fungi. Although the Fusarium incarnatum inoculation had a slight effect on the germination of ryegrass, it increased the biomass and enrichment coefficient. The results revealed a translocation factor (TF) value of 0.316 at 45 days after ryegrass sowing, showing significant enrichment of the soil Zn heavy metal zinc in the ryegrass roots.

Enrichment and delivery of bioavailable zinc by microalgae polyphosphate nanoparticles

Nanoscale delivery systems have gained a surge of interest in improving the stability, food compatibility, and bioavailability of essential minerals. Biogenic polyphosphate nanoparticles from microalgae have a great potential to enrich and deliver mineral nutrients. Here, zinc-enriched polyphosphate nanoparticles (ZnPNPs) with a zinc/calcium molar ratio of around 0.2 were obtained from Synechococcus sp. PCC 7002 supplemented with 3.75 mg/L zinc in the growth medium, and displayed small size and anionic nature with a monomer diameter of around 18 nm and a zeta potential of around −36 mV. Zinquin fluorescence measurements unveiled that ZnPNPs were well absorbed and readily incorporated into labile zinc pool by polarized Caco-2 cells in vitro. ZnPNPs showed good resistance to phytate's inhibition on zinc transportation across ligated mouse small intestine ex vivo at the phytate × calcium/zinc molar ratio as seen in baked whole wheat bread, and by treating with NaN3, amiloride, low temperature, chloroquine, and wortmanin, ZnPNPs transportation was found to invoke macropinocytic internalization, lysosomal degradation, and transcytosis. Oral pharmacokinetics and liver and skeletal muscle retention of zinc in rats revealed good in vivo zinc bioavailability of ZnPNPs under high dietary phytate conditions. Overall, ZnPNPs are attractive for zinc supplementation/fortification to populations on phytate-rich diets.

Potential of Zinc Oxide Nanoparticle for Dietary Fortification in Yoghurt: Physicochemical, Microbiological, Rheological and Textural Analysis

Background: Yoghurt is a widely consumed dairy product all over the world. It has been used as an apt fortification and nutrient delivery medium in recent years. Methods: The present study aimed to assess the suitability of zinc oxide (ZnO) nanoparticle as a potential source of fortification of zinc in yoghurt. Three different levels of ZnO nanoparticles, as well as micro-sized ZnO, were added in yoghurt. Physicochemical, sensory, microbiological, rheological and textural characteristics of yoghurt were determined during 7 days of storage at 7±1°C. Result: Significant differences in physicochemical properties were observed in yoghurt samples during storage. All the yoghurt samples showed non-Newtonian characteristics. Zinc oxide nanoparticle added @ 75 ppm was found best for yoghurt fortification and showed advantages over fortification with conventional micro-sized ZnO. In this study, the effects of fortification of yoghurt with zinc oxide nanoparticle during storage were investigated. The FFA content of yoghurt was found to be 0.46% oleic acid and the Peroxide Value was found to be 0.32 Milli equivalent/kg fat, which was found to increase during storage. The tyrosine value at zero day was found to be 2.2 mg/g. The LAB count was 10.59 log10 CFU/g. Plastic viscosity of yoghurt was found to be 10.8.3 cP. Fortification of yoghurt with zinc oxide nanoparticle proved to be advantageous over fortification with micro-sized zinc oxide in terms of physico-chemical, microbiological, rheological and textural characteristics. Fortification of yoghurt with zinc oxide nanoparticle proved to be highly promising for zinc enrichment in the food system.

A Comprehensive Recovery Process for Selective Separation and Enrichment of Copper, Zinc and Iron Minerals from a Polymetallic Ore and the Adsorption Mechanism of Collector Z-200

A comprehensive recovery process for the selective separation and enrichment of copper, zinc and iron minerals from a polymetallic ore was developed, which consisted of copper flotation, zinc flotation, and iron magnetic separation, and the adsorption mechanism of the copper collector Z-200 (O-isopropyl-N-ethyl thionocarbamate) was also studied in this work. The contents of the main valuable metallic elements of Cu, Zn and Fe in the ore were respectively 0.61%, 1.68% and 14.17%, and they mainly existed as chalcopyrite, sphalerite and magnetite, whose dissemination relationship was complex. Under the optimal conditions of this process, the recoveries of Cu, Zn and Fe in their respective concentrates reached 86.1%, 87.6% and 77.8%, and their grades were separately 20.31%, 45.97% and 63.39%. This process realized the selective separation and beneficiation of copper, zinc, and iron minerals from the ore, and had promising industrial application prospects. The adsorption configuration analysis demonstrated that the steadiest adsorption configurations of Z-200 on the surfaces of chalcopyrite, sphalerite and magnetite were the simultaneous adsorption of carbonyl S together with the O atom. Compared with sphalerite and magnetite, Z-200 was more prone to adsorb on the chalcopyrite surface. The Mulliken charge population and bond length analyses manifested that Z-200 chemically adsorbed on the chalcopyrite surface by forming a normal covalent bond and a back donation covalent bond, and the normal covalent bond played a leading role. The chemisorption of Z-00 was supported by the FTIR spectrum analysis result.

Modulation in Biofertilization and Biofortification of Wheat Crop by Inoculation of Zinc-Solubilizing Rhizobacteria.

Zinc is an important micronutrient needed for the optimum growth and development of plants. Contrary to chemical zinc fertilizers, the use of zinc-solubilizing bacteria is an environmentally friendly option for zinc enrichment in edible parts of crops. This study was conducted with the objective of selecting potential zinc-solubilizing rhizobacteria from the rhizosphere of chickpea grown in soils of eastern Uttar Pradesh and further assessing their impact on the magnitude of zinc assimilation in wheat crops. Among 15 isolates, CRS-9, CRS-17, CRS-30, and CRS-38 produced net soluble zinc in broth to the tune of 6.1, 5.9, 5.63, and 5.6 μg ml–1, respectively, in zinc phosphate with the corresponding pH of 4.48, 5.31, 5.2, and 4.76. However, the bacterial strains CRS-17, CRS-30, CRS-38, and CRS-9 showed maximum zinc phosphate solubilization efficiency of 427.79, 317.39, 253.57, and 237.04%, respectively. The four bacterial isolates were identified as Bacillus glycinifermentans CRS-9, Microbacterium oxydans CRS-17, Paenarthrobacter nicotinovorans CRS-30, and Bacillus tequilensis CRS-38 on the basis of morphological and biochemical studies and 16S rRNA gene sequencing. Bacterial inoculants significantly colonized the roots of wheat plants and formed a biofilm in the root matrix. These strains significantly increased seed germination (%) and vigor indices in wheat grown under glasshouse conditions. After 30 days of sowing of wheat under microcosm conditions, eight zinc transporter (TaZIP) genes were expressed maximally in roots, with concomitant accumulation of higher zinc content in the bacterially treated plant compared to the absolute control. Out of the four strains tested, two bacteria, B. tequilensis CRS-38 and P. nicotinovorans CRS-30, improved seed germination (%), vigor indices (2–2.5 folds), plant biomass, grain yield (2.39 g plant–1), and biofortificated grains (54.25 μg g–1Zn) of wheat. To the best of our knowledge, this may be the first report on the presence of zinc solubilization trait in B. glycinifermentans CRS-9, M. oxydans CRS-17, and P. nicotinovorans CRS-30.

Catchment Soil Properties Affect Metal(loid) Enrichment in Reservoir Sediments of German Low Mountain Regions

Sediment management is a fundamental part of reservoir operation, but it is often complicated by metal(loid) enrichment in sediments. Knowledge concerning the sources of potential contaminants is therefore of important significance. To address this issue, the concentrations and the mobile fractions of metal(loid)s were determined in the sediments and the respective catchment areas of six reservoirs. The results indicate that reservoirs generally have a high potential for contaminated sediment accumulation due to preferential deposition of fine particles. The median values of the element-specific enrichment factor (EF) demonstrates slight enrichments of arsenic (EF: 3.4), chromium (EF: 2.8), and vanadium (EF: 2.9) for reservoir sediments. The enrichments of cadmium (EF: 8.2), manganese (EF: 3.9), nickel (EF: 4.8), and zinc (EF: 5.0) are significantly higher. This is enabled by a diffuse element release from the soils into the impounded streams, which is particularly favored by soil acidity. Leaching from the catchment soils partially enriches elements in stream sediments before their fine-grained portions in particular are deposited as reservoir sediment. We assume that this effect is of high relevance especially for reservoirs impounding small streams with forested catchments and weakly acid buffering parent material of soil formation.

Zinc availability from zinc-enriched yeast studied with an in vitro digestion/Caco-2 cell culture model

BackgroundOrganic zinc sources for the treatment of zinc deficiency or as a supplement to a specific diet are increasingly needed. Zinc-enriched yeast (ZnYeast) biomass is a promising nutritional supplement for this essential micronutrient. However, these products are not yet authorized in the European Union and a clear position from the European Food Safety Authority on the use of ZnYeast as a zinc supplement is pending, demanding more data on its bioavailability. ObjectiveThe study aimed to produce a ZnYeast based on a Saccharomyces genus (S. pastorianus Rh), characterize its zinc enrichment quota, cellular distribution of zinc, and evaluate its zinc bioavailability after human digestion by comparing it to commonly used inorganic and organic zinc supplements (ZnO, ZnSO4, zinc gluconate, and zinc aspartate). Method and Main findingsThe zinc-enriched S. pastorianus Rh contained 5.9 ± 1.0 mg zinc/g yeast, which was predominantly localized on the cell surface according to its characterization on the microscale with scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX). Combined experiments with a human in vitro digestion model and the in vitro intestinal cell model Caco-2 showed that intestinal zinc bioavailability of digested yeast biomass was comparable to the other zinc supplements, apart from ZnO, which was somewhat less bioavailable. Moreover, zinc released from digested ZnYeast was available for biological processes within the enterocytes, leading to mRNA upregulation of metallothionein, a biomarker of intestinal zinc status, and significantly elevated the cellular labile zinc pool. ConclusionsOur findings demonstrated that ZnYeast represents a suitable nutritional source for organically bound zinc and highlighted optimization strategies for future production of dietary ZnYeast.

Combined use of foliar zinc fertilisation, thiamethoxam and propiconazole does not reduce their effectiveness for enriching zinc in wheat grains and controlling insects and disease

Agronomic biofortification is possible through foliar zinc fertilisation around the earing and early milk stage of wheat. Farmers can be encouraged to apply foliar zinc fertilisation if there is yield enhancement or if it is compatible with other pesticides which are used during these stages to control aphid and stripe rust. To investigate the effectiveness of tank-mix applications of fertiliser and pesticide for enriching grain zinc and controlling the spread of aphid and stripe rust, studies were conducted at Punjab Agricultural Univeristy, Ludhiana, India for 4 years (2017–18 to 2020–21). We tested tank-mixing of zinc (0.5% ZnSO4.7H2O) + thiamethoxam 25 WG (50 g/ha), zinc + propiconazole (500 mL/ha) and zinc + thiamethoxam + propiconazole with one foliar application at the milk stage and two foliar applications at the flag leaf and milk stages. We did not find any adverse effect of tank-mix application of zinc sulfate, thiamethoxam and propiconazole on zinc enrichment in grains, nor in aphid and stripe rust control. The grain zinc enhancement was 99.8–114.9, 100.2–112.1 and 98.0–115.5% with application of foliar Zn, foliar Zn + thiamethoxam and foliar Zn + thiamethoxam and propiconazole respectively. We also found 5.74% increased grain yield with foliar Zn + thiamethoxam and 7.24% increased grain yield in foliar Zn + thiamethoxam + propiconazole. Better net returns in combining Zn + thiamethoxam + propiconazole were also recorded. The results advocate for the tank-mix application of Zinc + thiamethoxam + propiconazole for pest management and Zn biofortification.

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

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

A novel preparation for siderophore‐assisted copper and zinc enrichment in yeast

Copper and zinc are essential trace elements for several biological activities and play an important role in living organisms. In this study, the role of siderophores obtained from 16 microorganisms isolated from an iron-rich environment was evaluated in the transport of zinc and copper in yeast. In addition, siderophores showing relevant transport activity were used in the preparation of metal-enriched yeast. Siderophores TZT-SH5I and TZT-ZTH2X significantly improved tolerance of Saccharomyces cerevisiae during growth under high concentrations of zinc/copper. Strains producing siderophores TZT-SH5I and TZT-ZTH2X were identified as Aspergillus sp and Penicillium sp, respectively. The orthogonal method was used to determine optimized conditions for siderophore-assisted copper and zinc enrichment of S. cerevisiae. The final intracellular content of organic Cu and Zn in S. cerevisiae grown in a siderophore-containing medium was 60.76 and 44.22 mg/g. This study provides a convenient and feasible new strategy for the preparation of supplements rich in organic trace elements. Novelty impact statement Bioaccumulation of essential trace elements (TEs) by microorganisms is one of the most important ways to TEs from inorganic into organic forms which can be more efficiently absorbed by humans. In the current study, a novel method for preparing copper and zinc-enriched yeast using siderophores from high iron environment microorganisms has been optimized and established. Significantly higher intracellular content of organic Cu and Zn in Saccharomyces cerevisiae grown in a siderophore-containing medium was obtained, which would provide a new idea and platform for the preparation of organic trace elements.

Maintenance of pomegranate arils quality by zinc enrichment, a comparison between zinc sulfate and nano zinc oxide

Pomegranate arils are very perishable which restricts the distribution and supply chains of arils. Zinc treatment not only may fortify arils, but also has the capability of preventing the growth of pathogens. This study was performed to compare two different forms of zinc including nano zinc oxide (nZnO) and zinc sulfate (ZnSO4), each one in four concentrations of 0 %, 0.4 %, 0.6 % and 0.8 %. Zinc enrichment was evaluated by atomic absorption. Zinc enriched arils were stored in polypropylene-packed containers weighing approximately 50 g at 5 °C and 90–95 % relative humidity. Sampling was done at 5 d intervals during 30 d of storage. Zinc content in arils treated with 0.8 % ZnSO4 was 37.5 times more than the control, which can be a very effective way to meet body nutritional needs. Zinc treatment had an effect on all measured indices. The highest amount of total soluble solids (TSS), titratable acidity (TA), total phenolic content (TPC), antioxidant activity and anthocyanin content, and the lowest weight loss (WL) were found in the arils treated with 0.8 % ZnSO4. Overall, 0.8 % ZnSO4 followed by 0.8 % nZnO treatments were the most beneficial treatments to increase the shelf life and to maintain arils qualitative characteristics.

Enrichment of zinc in Lactobacillus plantarum DNZ-4: Impact on its characteristics, metabolites and antioxidant activity

The current study was conducted to investigate the effects of zinc enrichment on the characteristics, metabolites and antioxidant activity of L. plantarum DNZ-4. Electron microscopy analysis showed that the ultrastructure of the zinc-enriched strain changed greatly both for surface and inside as compared to the control strain. The zinc-enriched strain showed higher acid production ability resulting in lower pH value. Resistance assays demonstrated that the zinc-enriched strain has stronger tolerance ability to acid, bile salt and H2O2 than that of the control strain. Metabolites analysis indicated that the various metabolites in the zinc-enriched strain were altered significantly as a result of amino acids, energy and fatty acid metabolism affected by zinc enrichment. Furthermore, the antioxidant properties of the zinc-enriched strain, including radical scavenging capacity and the antioxidative enzyme activity increased significantly. These results suggest that zinc addition had a positive effect on the physiologic function of L. plantarum DNZ-4.

Is there an association between zinc and COVID-19-associated mucormycosis? Results of an experimental and clinical study.

BackgroundThe enormous increase in COVID‐19–associated mucormycosis (CAM) in India lacks an explanation. Zinc supplementation during COVID‐19 management is speculated as a contributor to mucormycosis. We conducted an experimental and clinical study to explore the association of zinc and mucormycosis.MethodsWe inoculated pure isolates of Rhizopus arrhizus obtained from subjects with CAM on dichloran rose Bengal chloramphenicol (DRBC) agar enriched with (three different concentrations) and without zinc. At 24 h, we counted the viable colonies and measured the dry weight of colonies at 24, 48 and 72 h. We also compared the clinical features and serum zinc levels in 29 CAM cases and 28 COVID‐19 subjects without mucormycosis (controls).ResultsWe tested eight isolates of R arrhizus and noted a visible increase in growth in zinc‐enriched media. A viable count percentage showed a significantly increased growth in four of the eight isolates in zinc‐augmented DRBC agar. A time‐ and concentration‐dependent increase in the mean fungal biomass with zinc was observed in all three isolates tested. We enrolled 29 cases of CAM and 28 controls. The mean serum zinc concentration was below the reference range in all the subjects and was not significantly different between the cases and controls.ConclusionsHalf of the R arrhizus isolates grew better with zinc enrichment in vitro. However, our study does not conclusively support the hypothesis that zinc supplementation contributed to the pathogenesis of mucormycosis. More data, both in vitro and in vivo, may resolve the role of zinc in the pathogenesis of CAM.

Do nitrogen and zinc application alleviate the adverse effect of heat stress on wheat (Triticum aestivum L.)?

Late-season heat stress (LSH) is a limiting factor for wheat production. Besides, low zinc and poor protein diet usually is a problem in low-income countries. The primary calorie source in such countries is prepared from bread. This study aims to mitigate heat stress by zinc and nitrogen application and improve zinc and protein content in wheat grain. We did the field experiments as a split-split-plot based on a randomized complete block design with four replications to assess zinc and nitrogen’s possible mitigation effect on LSH and protein and zinc enrichment of wheat grain during two years. Factors included LSH by delay in planting date (optimum, late, and very late) as the main plot, nitrogen (0, 75, 150, and 225 kg ha–1) in subplots, and zinc (0, 10, and 20 kg ha–1) as sub-subplots. We measured yield, yield components, physiological traits, zinc, and protein contents in the grain. Results showed that the highest relative water content and cell-membrane thermal stability were attained at the optimum planting date, 150 kg N ha–1 and 20 kg Zn ha–1. The maximum chlorophyll a and carotenoids contents in wheat cells were recorded in the optimum planting date, 225 kg N ha–1, and 20 kg Zn ha–1. Heat stress reduced the grain yield. In the second year of the experiment, the grain number per unit area was more than that of the first year; however, the highest grain yield was achieved in the first year owing to the higher mean grain weight. Nitrogen application decreased the adverse effects of heat stress on grain yield by increasing the grain number. Zinc application diminished the adverse effects of heat stress by increasing the mean grain weight. The adverse impact of the LSH on grain yield was more than that of biological yield. Heat stress reduced the hectolitre weight and zinc content of the grain. Meanwhile, it increased grain protein. In general, under LSH, the application of 225 kg N ha–1 and 20 kg Zn ha–1 can reduce the adverse effects of heat on the grain quality and quantity.

Transition metals and metal complexes in autophagy and diseases.

Transition metals refer to the elements in the d and ds blocks of the periodic table. Since the success of cisplatin and auranofin, transition metal-based compounds have become a prospective source for drug development, particularly in cancer treatment. In recent years, extensive studies have shown that numerous transition metal-based compounds could modulate autophagy, promising a new therapeutic strategy for metal-related diseases and the design of metal-based agents. Copper, zinc, and manganese, which are common components in physiological pathways, play important roles in the progression of cancer, neurodegenerative diseases, and cardiovascular diseases. Furthermore, enrichment of copper, zinc, or manganese can regulate autophagy. Thus, we summarized the current advances in elucidating the mechanisms of some metals/metal-based compounds and their functions in autophagy regulation, which is conducive to explore the intricate roles of autophagy and exploit novel therapeutic drugs for human diseases.

Selection for functional performance in the evolution of cuticle hardening mechanisms in insects.

Calcified tissues have repeatedly evolved in many animal lineages and show a tremendous diversity of forms and functions. The cuticle of many insects is enriched with elements other than Calcium, a strategy of hardening that is taxonomically widespread but apparently poorly variable among clades. Here, we investigate the evolutionary potential of the enrichment with metals in insect cuticle at different biological levels. We combined experimental evidence of Zinc content variation in the mandibles of a target species (Chorthippus cazurroi [Bolívar]) with phylogenetic comparative analyses among grasshopper species. We found that mandibular Zinc content was repeatable among related individuals and was associated with an indicator of fitness, so there was potential for adaptive variation. Among species, Zinc enrichment evolved as a consequence of environmental and dietary influences on the physical function of the jaw (cutting and chewing), suggesting a role of natural selection in environmental fit. However, there were also important within and transgenerational environmental sources of similarity among individuals. These environmental influences, along with the tight relationship with biomechanics, may limit the potential for diversification of this hardening mechanism. This work provides novel insights into the diversification of biological structures and the link between evolutionary capacity and intra- and interspecific variation.

Zinc Enrichment in two Contrasting Genotypes of Triticum aestivum L. Grains: Interactions between Edaphic Conditions and Foliar Fertilizers.

This study aimed to assess the implications of Zn enrichment in wheat grains as a function of contrasting genotypes, edaphic conditions and foliar fertilizers. Triticum aestivum L. varieties Roxo and Paiva were grown in four production fields, and sprayed with ZnSO4 (0, 16.20 and 36.40 kg/ha) Zn-EDTA (0, 6.30 and 12.60 kg/ha) and Tecnifol Zinc (0, 3.90 and 7.80 kg/ha). The heterogeneous edaphic conditions of the wheat fields were chemically characterized, it being found that soil properties determine different Zn accumulation in the grains of both genotypes. Foliar spraying enhanced to different extents Zn content in the grains of both genotypes, but the average of enrichment indexes varied among the wheat fields. Zinc mostly accumulated in the embryo and vascular bundle and to a lesser extent in the endosperm. Grain yield and test weight sprayed by ZnSO4 gave the highest values in both genotypes, but the opposite was found for Zn-EDTA. Considering the color parameters, lightness and red–green transitions were found to be a conjunction of genotype characteristics, fertilization types and edaphic conditions prevailing in each field. It is concluded that the index of Zn enrichment in wheat grains is a docket of edaphic conditions, genotype and type of fertilization.

Late Holocene periods of copper mining in the Eisenerz Alps (Austria) deduced from calcareous lake deposits

• Geochemical proxies indicate mining activity during the Bronze and Iron Ages. • Variations of δ 15N and δ 34S point towards lake catchment changes. • Pb enrichments in the calcareous deposits are not consistent with supra-regional amtospheric Pb peaks. Palynological studies and archaeological discoveries suggest repeated extensive prehistoric copper mining in the Eisenerz Alps (Styria, Austria). In an attempt to reconstruct the specific temporal evolution of copper (Cu) mining activity in this area from the Bronze Age to the medieval period, this article presents records of elemental variations, trace elemental enrichments of Cu, nickel (Ni), zinc (Zn), arsenic (As), cadmium (Cd), antimony (Sb) and lead (Pb) as well as light stable isotopes of nitrogen ( δ 15 N) and sulfur ( δ 34 S) as preserved in a calcareous sediment core retrieved from Lake Leopoldstein (Eisenerz). While the multi-element geochemical approach covers a time period from the Early Bronze Age to the mid-medieval period (2070 BCE – 850 CE), isotopic analyses were conducted up to a core depth of 660 cm, corresponding to about 3100 BCE. A comparative study of the parameters revealed strong indications of regional mining during the mid-Bronze Age (∼15th – 14th century BC), the Hallstatt period (∼8th – 6th century BC) and in the late La Tène period (∼3st century BC). Statistical evaluation of the data highlighted a good correlation of trace elements associated with local copper ores (fahlores, chalcopyrite). Enrichments of Pb, in contrast, are characterised by a more substantial deviation from the general trace element trend and are mainly linked to lithogenic input. Overall, the results of this study underscore the necessity of a broad-based multi-proxy approach in order to reconstruct periods of past mining activity based on the analysis of calcareous lake sediments. Especially, δ 15 N and δ 34 S revealed no particular potential for identifying past mining activity. However, both proxies were helpful for inferring erosional changes in the lake catchment, and thus for unraveling the interdependencies between geogenic and anthropogenic signals. Our study sheds new light on prehistoric copper mining in Central Europe.

Dietary zinc enrichment reduces the cadmium burden of mealworm beetle (Tenebrio molitor) larvae

The industrial production of Tenebrio molitor L. requires optimized rearing and processing conditions to generate insect biomass with high nutritional value in large quantities. One of the problems arising from processing is a tremendous loss in mineral accessibility, affecting, amongst others, the essential trace element Zn. As a feasible strategy this study investigates Zn-enrichment of mealworms during rearing to meet the nutritional requirements for humans and animals. Following feeding ZnSO4-spiked wheat bran substrates late instar mealworm larvae were evaluated for essential micronutrients and human/animal toxic elements. In addition, growth rate and viability were assessed to select optimal conditions for future mass-rearing. Zn-feeding dose-dependently raised the total Zn content, yet the Znlarvae/Znwheat bran ratio decreased inversely related to its concentration, indicating an active Zn homeostasis within the mealworms. The Cu status remained stable, suggesting that, in contrast to mammals, the intestinal Cu absorption in mealworm larvae is not affected by Zn. Zn biofortification led to a moderate Fe and Mn reduction in mealworms, a problem that certainly can be overcome by Fe/Mn co-supplementation during rearing. Most importantly, Zn feeding massively reduced the levels of the human/animal toxicant Cd within the mealworm larvae, a technological novelty of outstanding importance to be implemented in the future production process to ensure the consumer safety of this edible insect species.