Copper Uptake Research Articles

The influence of fungi of the Trichoderma genus on the flowering of Freesia refracta Klatt 'Argentea' in winter

The flowering and quality of Freesia refracta Klatt ‘Argentea’ were assessed after the application of fungi of the Trichoderma genus and assimilation lighting. The assimilation lighting accelerated the flowering of the Freesia refracta ‘Argentea’ plants by 3–4 weeks. The fungi of the Trichoderma genus accelerated the flowering of the Freesia refracta ‘Argentea’ plants with light deficit by about one week. The assimilation lighting resulted in the development of shorter main inflorescence shoots regardless of the fact whether the plants had been treated with the fungi of the Trichoderma genus or not. The assimilation lighting and the fungi of the Trichoderma genus stimulated the development of lateral inflorescence shoots in the ‘Argentea’ cultivar. The fungi of the Trichoderma genus stimulated the development of flowers in the ‘Argentea’ cultivar. This effect was particularly noticeable when the plants were exposed to the assimilation lighting. The assimilation lighting stimulated the uptake of potassium in the ‘Argentea’ cultivar. The fungi of the Trichoderma genus stimulated the uptake of phosphorus and calcium in the plants underexposed to light. They also stimulated the uptake of potassium in the plants exposed to the assimilation lighting. The assimilation lighting stimulated the uptake of microelements. The fungi of the Trichoderma genus stimulated the uptake of iron, manganese and zinc both in the plants exposed to the assimilation lighting and those underexposed to light. The assimilation lighting combined with the treatment with the fungi of the Trichoderma genus stimulated the uptake of copper.

Rapid Hormetic Responses of Photosystem II Photochemistry of Clary Sage to Cadmium Exposure.

Five-day exposure of clary sage (Salvia sclarea L.) to 100 μM cadmium (Cd) in hydroponics was sufficient to increase Cd concentrations significantly in roots and aboveground parts and affect negatively whole plant levels of calcium (Ca) and magnesium (Mg), since Cd competes for Ca channels, while reduced Mg concentrations are associated with increased Cd tolerance. Total zinc (Zn), copper (Cu), and iron (Fe) uptake increased but their translocation to the aboveground parts decreased. Despite the substantial levels of Cd in leaves, without any observed defects on chloroplast ultrastructure, an enhanced photosystem II (PSII) efficiency was observed, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in an important decrease in the dissipated non-regulated energy (ΦNO), modifying the homeostasis of reactive oxygen species (ROS), through a decreased singlet oxygen (1O2) formation. A basal ROS level was detected in control plant leaves for optimal growth, while a low increased level of ROS under 5 days Cd exposure seemed to be beneficial for triggering defense responses, and a high level of ROS out of the boundaries (8 days Cd exposure), was harmful to plants. Thus, when clary sage was exposed to Cd for a short period, tolerance mechanisms were triggered. However, exposure to a combination of Cd and high light or to Cd alone (8 days) resulted in an inhibition of PSII functionality, indicating Cd toxicity. Thus, the rapid activation of PSII functionality at short time exposure and the inhibition at longer duration suggests a hormetic response and describes these effects in terms of “adaptive response” and “toxicity”, respectively.

Cyclic Copper Uptake and Release from Natural Seawater-A Fully Sustainable Antifouling Technique to Prevent Marine Growth.

Unwanted growth of fouling organisms on underwater surfaces is an omnipresent challenge for the marine industry, costing billions of dollars every year in the transportation sector alone. Copper, the most widely used biocide in antifouling paints, is at the brink of a total ban in being used in antifouling coatings, as it has become an existential threat to nontargeted species due to anthropogenic copper inputs into protected waters. In the current study, using a porous and cross-linked poly(ethylene imine) structure under marine and fouling environments, available copper from natural seawater was absorbed and electrochemically released back as a potent biocide at 1.3 V vs Ag|AgCl, reducing marine growth by 94% compared to the control electrode (coupon) at 0 V. The coating can also function as an electrochemical copper sensor enabling real-time monitoring of the electrochemical uptake and release of copper ions from natural seawater. This allows tailoring of the electrochemical program to the changing marine environments, i.e., when the vessels move from high-copper-contaminated waters to coastal regions with low concentrations of copper.

Modelling copper toxicokinetics in the zebra mussel, Dreissena polymorpha, under chronic exposures at various pH and sodium concentrations

The stenohaline zebra mussel, Dreissena polymorpha, is uniquely sensitive to the ionic composition of its aquatic environment. Waterborne copper (Cu) uptake and accumulation in zebra mussels were examined at various conditions in an environmentally relevant range in freshwater, i.e. Cu exposure levels (nominal concentrations of 25 and 50 μg/L), pH (5.8–8.3), and sodium (Na+) concentrations (up to 4.0 mM). Copper accumulation was simulated by a kinetic model covering two compartments, the gills and the remaining tissues. The Cu uptake rate constant decreased with decreasing pH from 8.3 down to 6.5, indicating interactions between H+ and Cu at uptake sites. The kinetic simulation showed dose-dependent effects of Na+ on Cu uptake. At 25 μg/L Cu, addition of Na+ at 0.5 mM significantly inhibited the Cu uptake rate, while no significant differences were found in the uptake rate upon further addition of Na+ up to a concentration of 4.0 mM. At 50 μg/L Cu, the Cu uptake rate was not influenced by Na+ addition. Calibration results exhibited dose-dependent elimination rates with more profound elimination with increasing exposure levels. With kinetic parameters calibrated at environmentally relevant conditions, in terms of pH and Na+ concentrations, the model performed well in predicting Cu accumulation based on independent data sets. Estimates of the Cu concentration in mussels were within a factor of 2 of the measurements. This demonstrates potential application of kinetic models that are calibrated in environmentally relevant freshwater conditions.

Neuron-glia: understanding cellular copper homeostasis, its cross-talk and their contribution towards neurodegenerative diseases.

Over the years, the mechanism of copper homeostasis in various organ systems has gained importance. This is owing to the involvement of copper in a wide range of genetic disorders, most of them involving neurological symptoms. This highlights the importance of copper and its tight regulation in a complex organ system like the brain. It demands understanding the mechanism of copper acquisition and delivery to various cell types overcoming the limitation imposed by the blood brain barrier. The present review aims to investigate the existing work to understand the mechanism and complexity of cellular copper homeostasis in the two major cell types of the CNS - the neurons and the astrocytes. It investigates the mechanism of copper uptake, incorporation and export by these cell types. Furthermore, it brings forth the common as well as the exclusive aspects of neuronal and glial copper homeostasis including the studies from copper-based sensors. Glia act as a mediator of copper supply between the endothelium and the neurons. They possess all the qualifications of acting as a 'copper-sponge' for supply to the neurons. The neurons, on the other hand, require copper for various essential functions like incorporation as a cofactor for enzymes, synaptogenesis, axonal extension, inhibition of postsynaptic excitotoxicity, etc. Lastly, we also aim to understand the neuronal and glial pathology in various copper homeostasis disorders. The etiology of glial pathology and its contribution towards neuronal pathology and vice versa underlies the complexity of the neuropathology associated with the copper metabolism disorders.

Dietary uptake and effects of copper in Sticklebacks at environmentally relevant exposures utilizing stable isotope-labeled 65CuCl2 and 65CuO NPs

Copper oxide nanoparticles (CuO NPs) accumulating in sediment can be taken up by invertebrates that serve as prey for fish. Thus, it is likely that the latter are exposed to CuO NPs via the gut. However, to this day it is unknown if CuO NPs can be taken up via the gastrointestinal tract and if and in which tissues/organs they accumulate. To address this knowledge gap, we synthesized CuO NPs enriched in the stable isotope 65Cu and incorporated them at low concentration (5 μg 65Cu g−1 ww food) into a practical diet prepared from worm homogenate, which was then fed to Three-spined Stickleback (Gasterosteus aculeatus) for 16 days. For comparison, fish were exposed to a diet spiked with a 65CuCl2 solution. Background Cu and newly taken up 65Cu in fish tissues/organs including gill, stomach, intestine, liver, spleen, gonad and carcass and feces were quantified by ICP-MS. In addition, expression levels of genes encoding for proteins related to Cu uptake, detoxification and toxicity (ctr-1, gcl, gr, gpx, sod-1, cat, mta and zo-1) were measured in selected tissues using RT-qPCR. The obtained results showed that feces of fish fed 65CuO NP-spiked diet contained important amounts of 65Cu. Furthermore, there was no significant accumulation of 65Cu in any of the analyzed internal organs, though 65Cu levels were slightly elevated in liver. No significant modulation in gene expression was measured in fish exposed to 65CuO NP-spiked diet, except for metallothionein, which was significantly upregulated in intestinal tissue compared to control fish. Altogether, our results suggests that dietary absorption efficiency of CuO NPs, their uptake across the gastrointestinal barrier into the organism, and effects on Cu-related genes is limited at low, environmentally relevant exposure doses (0.2 μg 65Cu −1 fish ww day−1).

Impacts of zinc oxide nano and bulk particles on redox-enzymes of the Punica granatum callus

The structure and function of cellular membranes were sustained by redox-enzymes. We studied the interaction between the oxidative stress caused by excessive accumulation of ZnO-nanoparticles (ZnO-NPs) in plants and the role of redox-enzymes that can alleviate this stress. The crude callus extract from pomegranate, which was treated with 0, 10, and 150 µg mL−1 ZnO-NPs or bulk particles (ZnO-BPs), was applied to study the activity and kinetics of redox-enzymes. The elevated ZnO-NPs, enhanced the lipoxygenase and polyphenol oxidase activity, while the ZnO-BPs did not modify them. The activities of superoxide dismutase, catalase, and phenylalanine ammonia-lyase were induced under ZnO-NPs or BPs treatments, whilst the opposite trend of peroxidase was observed. Ascorbate peroxidase activity increased under ZnO-NPs treatments but decreased under ZnO-BPs. The kinetics activity of enzymes showed changes under different levels of NPs and BPs. Additionally, NPs or BPs treatments reduced the uptake of copper, iron, magnesium, but increased zinc accumulation in callus tissues. Meanwhile, these treatments enhanced the accumulation of manganese ions but did not affect the accumulation of potassium and phosphorous in ZnO-NPs or BPs-stressed calli. Collectively, these results gave a quantitative evaluation of the competition of zinc and other minerals on the carriers, and in addition, they provided a basis for how to control ZnO-NPs or BPs toxicity via redox-enzymes.

Potential Benefits of Silicon Nutrition to Hydroponically Grown Sweet Basil

Sweet basil (Ocimum basilicum L.) is a globally cultivated and consumed herb known for its unique aroma and flavor. Sweet basil grows best in warm temperatures, and productivity and marketability decrease when grown under cool conditions (<10 °C). Silicon (Si) is not considered an essential plant nutrient, but it can be beneficial to Si macroaccumulator plants by alleviating several biotic and abiotic stresses. Recent studies have shown that some microaccumulator species may also benefit from Si. In this study, we examined the effects of different levels (0, 25, and 75 ppm Si) of Si amendments on hydroponic basil grown at 23 °C. Si (75 ppm) significantly increased shoot height and weight with no negative impact on plant morphology. All Si-treated basil plants absorbed Si in small quantities and affected the uptake of phosphorus, magnesium, sulfur, iron, manganese, copper, zinc and molybdenum. After an unintentional frost event, basil plants treated with 75 ppm had significantly higher survival rates and reduced cold injury symptoms. We concluded that Si amendments can have a positive impact on hydroponically grown sweet basil, and that such amendments may reduce plant damage due to occasionally cooler growing temperatures.

The bifunctional role of copper nanoparticles in tomato: Effective treatment for Fusarium wilt and plant growth promoter

Both the effectiveness of copper nanoparticles (Cu-NPs) as a treatment for Fusarium wilt and the role of Cu-NPs in promoting tomato plant growth were studied. First, we evaluated the in vitro antifungal activity of Cu-NPs at different concentrations (0.1, 0.25, 0.5, 0.75, and 1.0 mg/mL) against Fusarium oxysporum f. sp. lycopersici (FOL). A strong inhibitory effect on mycelial FOL growth (67.3%) was observed with 0.5 mg/mL Cu-NPs compared to a commercial fungicide based on copper hydroxide, whose inhibitory effect was only 15.6%. Next, in in vivo experiments at the same concentration, Cu-NPs significantly diminished the symptoms of Fusarium wilt by 68 and 66.5% for incidence and severity, respectively. Moreover, the treatments with Cu-NPs increased the growth of tomato plants and particularly raised the chlorophyll content (from 19.3 to 28.6%). This is because Cu-NPs effectively deliver copper as a micronutrient for the plants, while the uncontrolled uptake of copper ions from the commercial fungicide (copper hydroxide) inhibits the healthy development of plants. Importantly, despite the principal function of Cu-NPs as a fungicide, Cu-NPs may be applied as fertilizer for tomato plants. Thus, the application of Cu-NPs effectively treats Fusarium wilt while promoting the growth of tomato plants. Therefore, these results suggest that copper nanomaterials may be used as both a source of micronutrients in cases of soil copper deficiency and as a fungicide. In terms of sustainability, this multifunctionality has the potential to positively impact the environment.

Influence of Species Differences, Relative Metals Concentrations and pH on Uptake of Metals in Water by Fish

This study was designed to assess the effect of relative metals concentrations, pH and species variations on the uptake of copper (Cu), iron (Fe), calcium (Ca) and magnesium (Mg) in water, fish and fish parts to monitor the toxicity potentials of consuming these fish. The water and fish samples were obtained from four locations (Farin gada stream, Lamingo Dam, Nasco pond and mining pond) in Jos Metropolis, Plateau State, Nigeria, Water and six fish species samples were collected from the four locations, digested and analysed using Buck Scientific Atomic Absorption Spectrophotometer, model 210VGP. Results show that pH of the water sources from Farin gada stream, Lamingo Dam, Nasco pond and mining pond were 7.1, 6.5, 7.0 and 7.2 respectively. The concentrations of Cu in the water sources were 0.030±0.001, 0.010±0.003, 0.020±0.000, 0.027±0.000 in Farin Gada stream, Nasco pond, Lamingo Dam and mining pond respectively; Fe were 2.2±0.1, 0.0±0,000, 0.2±0.003 and 0.3±0.001; Ca were 305±3.0, 37±1.5, 110±3.5 and 163±4.5; Mg were 160±3.6, 126±4.8, 79±1.9 and 95±2.8 in that order above. Different fish species from the same water source bioaccumulated Cu, Fe, Ca and Mg at varying concentrations depending on source, fish species or the physicochemical properties. Different fish species have different preferences as to which part (body, gills and head) of the fish these metals are concentrated more. Lamingo Dam had five fish species, mining pond had three, while Nasco pond and Farin Gada stream had one each. The results established that uptake and bioavailability of Cu, Fe, Ca and Mg by fish in water depend on species variation, relative concentration of the metals in the source of water and the pH of the water.

Root System Architecture, Copper Uptake and Tissue Distribution in Soybean (Glycine max (L.) Merr.) Grown in Copper Oxide Nanoparticle (CuONP)-Amended Soil and Implications for Human Nutrition.

Understanding the potential uptake and biodistribution of engineered nanoparticles (ENPs) in soil-grown plants is imperative for realistic toxicity and risk assessment considering the oral intake of edibles by humans. Herein, growing N-fixing symbiont (Bradyrhizobium japonicum) inoculated soybean (Glycine max (L.) Merr.) for a full lifecycle of 120 days, we assessed the potential influence of particle size (25, 50, and 250 nm) and concentration (0, 50, 100, 200, and 500 mg/kg soil) of Copper oxide nanoparticles (CuONPs) on: (1) root system architecture, (2) soil physicochemical attributes at the soil–root interface, and (3) Cu transport and accumulation in root, stem, leaf, and seed in soybean, and compared them with the soluble Cu2+ ions and water-only controls. Finally, we performed a comparative assessment of total seed Cu levels in soybean with other valuable food sources for Cu intake and discussed potential human health implications. Results showed particle size- and concentration-dependent influence of CuONPs on Cu uptake and distribution in root, stem, leaf, and seed. Alterations in root architecture (root biomass, length, volume, and area) were dependent on the Cu compound types, Cu concentrations, and their interactions. Concentration–response relationships for all three sizes of CuONPs and Cu2+ ions were found to be linear. Furthermore, CuONPs and Cu2+ ions had inhibitory effects on root growth and development. Overall, soybean responses to the smallest size of CuONPs–25 nm—were greater for all parameters tested compared to the two larger-sized CuONPs (50 nm, 250 nm) or Cu2+ ions. Results suggest that minor changes in soil-root physicochemical attributes may not be a major driver for Cu uptake in soybean. Cu bioaccumulation followed the order: root > leaf > stem > seed. Despite reduction in root architecture and seed yield, the smallest size CuONPs–25 nm led to increased total seed Cu uptake compared to the larger-sized CuONPs or Cu2+ ions. Our findings also suggest that soil amendment with CuONPs, and more so with the smallest size of CuONPs–25 nm—could significantly improve seed nutritional Cu value in soybean as reflected by the % Daily Values (DV) and are rated “Good” to “Very Good” according to the “World’s Healthiest Foods” rating. However, until the potential toxicity and risk from CuONP-fortified soybean seed ingestion is characterized in humans, we caution recommending such seeds for daily human consumption when addressing food Cu-deficiency and associated diseases, globally.

Development of whole-cell and cell-free biosensors for the detection and differentiation of organic and inorganic forms of copper.

The modern world has seen exposure of bacterial communities to toxic metals at selective levels. This manifests itself both intentionally, through medicines and un-intentionally through waste streams. There is growing concern that selective exposure to metals may be linked to microbial resistance to antibiotics. For a microbe to become resistant to a specific metal it must first come in contact with it. The transition metal copper has the ability to enter bacterial cells without need for a copper specific uptake mechanism. Copper is commonly used as an antimicrobial in the healthcare industry, consumer products and as a growth promoter of livestock in the agricultural sector. Here we report a study into the uptake of different organic and inorganic sources of copper. A whole-cell bacterial biosensor was developed to quantify the specific uptake of copper from various sources. Furthermore, a cell-free sensor was utilized to investigate the response to copper sources when uptake is eliminated as a factor. The data within suggest inorganic copper to have greatly reduced uptake compared to organic sources and that there is significant difference between copper oxides, Cu2O and CuO.

Fractions of copper in soil and their contribution to copper availability and uptake in maize–wheat cropping system under Typic hapludalfs

Long-term effects of integrated application of organics and chemical fertilizers on transformation of copper (Cu) into various chemical pools and their availability under maize–wheat cropping system were investigated in the ongoing long-term fertilizer experiment initiated in 1972 at the research farm of Chaudhary Sarwan Kumar Himachal Pradesh Agricultural University on an acidic soil in the Western Himalayas of India. The continuous use of chemical fertilizers alone for 36 years brought about marked depletion in all forms of copper except organically bound Cu (Cu-III) compared to buffer plots. Integrated use of organics and chemical fertilizers gave higher content of Cu forms over chemically treated plots except Cu occluded by free oxides (Cu-IV). Residual Cu was the most dominant form of copper contributing about 62% of the total Cu. Organically bound Cu (Cu-III) was the most important fraction of copper contributing toward DTPA (diethylene triamine pentaacetic acid) extractable Cu. Content of DTPA-extractable Cu increased over control when chemical fertilizers were applied in conjunction with different organics, whereas DTPA-Cu content declined over control with application of chemical fertilizers alone for the last 36 years.

Effect of calcium and boron on biomass yield and nutrients uptake by tomato (Solanum lycopersicum)

A pot experiment was conducted in acid soil (Alfisol) using four levels of lime (CaCO3) based on lime requirement (LR), viz. 0, 1/3, 2/3, and 1 and four levels of boron (B), viz. 0, 1.0, 1.5 and 2 mg/kg to evaluate the effect of applied calcium (Ca) and boron (B) on biomass yield, nutrient uptake of tomato (Solanum lycopersicum L.) and soil properties. The results indicated that application of Ca @ 2/3 LR and 1 LR significantly increased biomass yield of tomato by 21% and 16%, respectively over control. Boron application @ 1.0 mg/kg recorded highest biomass yield (19.6 g/pot) of tomato as compared to other boron treatments. Applied Ca @ 2/3 LR significantly increased the uptake of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S), zinc (Zn) and copper (Cu), whereas iron (Fe), manganese (Mn) and B uptake increased only up to Ca @ 1/3 LR treatment. Application of B increased the nutrients uptake over control, whereas it was observed significantly higher with B @ 1.5 mg/kg treatment. Applied Ca significantly enhanced the pH and available Ca in post-harvest soil, whereas salicylic acid extractable boron (SAE-B) was declined. The combined application of calcium @ 2/3 LR and B @ 1.5 mg/kg was most effective in enhancing the yield and nutrient uptake of tomato.

The Garden Candytuft (Iberis umbellata L.): At the Crossroad of Copper Accumulation and Glucosinolates

The copper accumulation ability and its impact on the glucosinolate content of the garden candytuft were studied. Different copper sources (adsorbents or solution) were used. Generally, the seedlings copper uptake from the adsorbents was in the amount needed for its growth and development with the beneficial or no impact on the glucosinolate content. The lowest copper concentration was detected in the total seedlings biomass which grew in the humus with the addition of Cu-exchanged zeolite NaX (27.88 μg g−1 DW) having glucosinolate content of 9757.81 µg g−1 DW (23.86 µmol g−1 DW). The highest copper concentration among all the garden candytuft samples was detected in the seedlings watered with CuSO4∙5H2O solution (514.63 μg g−1 DW) with a sharp decrease of the glucosinolate content 3103.33 µg g−1 DW (7.59 µmol g−1 DW). Based on the results obtained, the garden candytuft can be considered as a copper accumulator plant.

Selective Emulsion Liquid Membrane Extraction of Cu(II) Mediated by a Schiff Base Ligand

This study concerns on the application of a Schiff base ligand of type N3O2 as a carrier in a water-in-oil emulsion liquid membrane for the selective transport of copper ions. A hydrochloric acid solution formed the internal aqueous phase (receiving phase), and the membrane was composed of a Schiff base ligand called bis(1'-hydroxy-2'-acetonaphthone)-2,2'-diiminodiethylamine (L) in dichloromethane and the non-ionic surfactant Span® 80 in paraffin. By applying the optimum conditions, a quantitative uptake of copper ions (initial concentration 5 mg L-1) from the aqueous feed phase (pH 5) into the receiving phase (hydrochloric acid 0.7 mol L-1), after 10 min was attained. The optimal value determined for the treat ratio allows achieving to a concentration factor of >6 for the copper ions in the receiving phase. The proposed emulsion liquid membrane provided an excellent selectivity towards copper ions with respect to some associated metal ions including Cd(II), Ni(II), Zn(II), Co(II), Fe(II), and Cr(III). However, such selectivity was not observed in the competition of Cd(II) and Pb(II) ions. The breakage of emulsions and recovery of the internal phase from the membrane was performed by freezing the internal solution. In fact, the expansion of the frozen internal phase volume results in breakage of the emulsions. The applicability of the proposed procedure was appraised by employing the method for the recovery of copper from the leached solutions of the cobalt and nickel-cadmium filter-cakes of a zinc production plant.

Reactivity towards DNA and protein, cellular uptake, cytotoxic activity of a mononuclear copper(II) complex of the thioflavin-T (ThT)-based derivative

DNA- and protein-binding properties, cellular uptake, and cytotoxicity activity of a mononuclear copper(II) complex, [CuLCl2] (1, where L = 4′-bis(pyridine-2-ylmethyl)amiono-2-phenylbenzothiazole), were investigated. The results show that 1 can effectively enter the cancer cells, even the nucleus, and exhibit cytotoxicity comparable to that of cisplatin against A549 and MCF-7 cell lines. Complex 1 could strongly bind to calf-thymus DNA (CT-DNA) mainly by intercalation mode and induce a remarkable conformational variation of DNA. The intrinsic binding constant K b of 1 to DNA is 4.15 × 105 M−1 and the apparent binding constant K app is 1.25 × 106 M−1. Agarose gel electrophoresis revealed that 1 could efficiently cleave the supercoiled pBR322 DNA into its nicked and linear forms in the presence of excessive H2O2. The evaluation of the protein binding ability showed that 1 could also bind to human serum albumin (HSA) with a moderate binding affinity, quench the intrinsic fluorescence of HSA, and induce the conformational change of the protein.

Mammalian copper homeostasis requires retromer-dependent recycling of the high-affinity copper transporter 1.

ABSTRACTThe concentration of essential micronutrients, such as copper (used here to describe both Cu+ and Cu2+), within the cell is tightly regulated to avoid their adverse deficiency and toxicity effects. Retromer-mediated sorting and recycling of nutrient transporters within the endo-lysosomal network is an essential process in regulating nutrient balance. Cellular copper homeostasis is regulated primarily by two transporters: the copper influx transporter copper transporter 1 (CTR1; also known as SLC31A1), which controls the uptake of copper, and the copper-extruding ATPase ATP7A, a recognised retromer cargo. Here, we show that in response to fluctuating extracellular copper, retromer controls the delivery of CTR1 to the cell surface. Following copper exposure, CTR1 is endocytosed to prevent excessive copper uptake. We reveal that internalised CTR1 localises on retromer-positive endosomes and, in response to decreased extracellular copper, retromer controls the recycling of CTR1 back to the cell surface to maintain copper homeostasis. In addition to copper, CTR1 plays a central role in the trafficking of platinum. The efficacy of platinum-based cancer drugs has been correlated with CTR1 expression. Consistent with this, we demonstrate that retromer-deficient cells show reduced sensitivity to the platinum-based drug cisplatin.

A novel assessment system of toxicity and stability of CuO nanoparticles via copper super sensitive Saccharomyces cerevisiae mutants

CuO nanoparticles (CuO-NPs) toxicity in organisms is contributed mainly through the copper uptake by both the ionic and nanoparticle form. However, the relative uptake ratio and bioavailability of the two different forms is not well known due to a lack of sensitive and effective assessment systems. We developed a series of both copper resistant and hyper sensitive Saccharomyces cerevisiae mutants to investigate and compare the effects of CuO-NPs and dissolved copper (CuCl2), on the eukaryote with the purpose of quantitating the relative contributions of nanoparticles and dissolved species for Cu uptake. We observed the toxicity of 10 mM CuO-NPs for copper sensitive strains is equal to that of 0.5 mM CuCl2 and the main toxic effect is most likely generated from oxidative stress through reactive oxygen species (ROS) production. About 95% CuO-NPs exist in nanoparticle form under neutral environmental conditions. Assessing the cellular metal content of wild type and copper transporter 1(CTR1) knock out cells showed that endocytosis is the major absorption style for CuO-NPs. This study also found a similar toxicity of Ag for both 10 mM Ag-NPs and 0.2 mM AgNO3 in the copper super sensitive strains. Our study revealed the absorption mechanism of soluble metal based nanomaterials CuO-NPs and Ag-NPs as well as provided a sensitive and delicate system to precisely evaluate the toxicity and stability of nanoparticles.

Additive interactions of nanoparticulate ZnO with copper, manganese and iron in Pisum sativum L., a hydroponic study

Widespread occurrence of ZnO nanoparticles in environment follows the growing number of applications either in technology or agriculture. The impact of five forms of nanoparticulate ZnO on copper, manganese and iron uptake by Pisum sativum L. cultivated in Hoagland solutions was investigated. Plants were collected after twelve days of zinc administration. Effect of bulk ZnO has also been studied. Initial zinc concentration was 100 mg L−1. Nanoparticles were characterized by the Transmission Electron Microscopy, Dynamic Light Scattering and Zeta potential measurements. Metal contents were analyzed using the Atomic Absorption Spectrometry with flame atomization for samples digested in a microwave closed system. Analysis of variance indicated that zinc species at either molecular or nanoscale levels altered Cu, Mn and Fe uptake and their further transport in pea plants. In particular, significant reduction of Mn and Fe combined with the Cu increase was observed. Additive interactions originated by nanoparticles affect the heavy metals uptake and indicate pollutants migration pathways in plants. Unfortunately, regulations for the plant cultivation were formulated when anthropogenic nanoparticles were not in common use. They underestimate complexity of metals interactions in either plant or habitat. Our results indicate that these additive interactions cannot be neglected and deserve further investigations.