Effects of exogenous nitric oxide on photosynthesis,antioxidative ability,and mineral element contents of perennial ryegrass under copper stress

A hydroponics experiment was conducted to test the effects of sodium nitroprusside (SNP, a donor of NO) supplied with different concentrations on copper (Cu) toxicity in ryegrass seedlings (Lolium perenne L.). Excess Cu (200 µM) reduced chlorophyll content, resulting a decrease in photosynthesis. Cu stress induced the production of hydrogen peroxide (H₂O₂) and superoxide anion (O₂^{? ?}), leading to malondialdehyde (MDA) accumulation. Furthermore, activities of antioxidant enzymes in Cu-treated seedlings such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were decreased. In addition, Cu stress inhibited the uptake of K, Mg, Fe, and Zn and increased Ca content in roots. Moreover, in leaves of Cu-stressed seedlings, K, Fe, and Zn contents were decreased and the contents of Ca and Mg were not affected significantly. In Cu-treated seedlings, Cu concentration in roots was higher than in leaves. Addition of 50, 100, 200 µM SNP in Cu-mediated solutions increased chlorophyll content and photosynthesis, improved antioxidant enzyme activities, reduced Cu-induced oxidative damages, kept intracellular ion equilibrium under Cu stress, increased Cu concentration in roots and inhibited Cu accumulation in leaves. In particular, addition of 100 µM SNP had the best effect on promoting growth of ryegrass seedlings under Cu stress. However, the application of 400 µM SNP had no obvious alleviating effect on Cu toxicity in ryegrass seedlings.     

Physiological responses of Bituminaria bituminosa to heavy metals

Two hydroponic experiments were performed to study the physiological responses to heavy metals (HMs) of two populations of Bituminaria bituminosa (L.) C.H. Stirton (Fabaceae): one (“C2”) from a site contaminated by HMs and one from a non-contaminated site (“LA”). In the first, we studied the effects of elevated concentrations of Zn (12 and 61 μM). Population C2 was more tolerant in terms of root and shoot growth at 61 μM Zn, relative to control plants (1 μM Zn). The similar tissue Zn levels of the two populations suggest that C2 is more tolerant of high tissue Zn. Of the parameters measured that could be related to Zn phytotoxicity (micro and macronutrients, root hydraulic activity, water-extractable Zn and organic acids), none could explain totally the superior tolerance of C2. In the second assay, the effects of Cd (4.4 μM), Cu (7.8 μM) and Zn (76 μM) on plant accumulation of the furanocoumarins (FCs) psoralen and angelicin, which function as feeding deterrents and photo-activated toxins, were assessed. For population C2, all three HMs increased the root FC concentrations, while Cd also raised shoot levels. For LA, Cu raised the root concentrations of both FCs. There was a relationship between plant stress, manifested as proline accumulation and disruption of plant water relations, and increased FC accumulation. Higher tissue levels of FCs likely provide greater protection against bacterial or fungal infection and herbivores.     

Relationship between ammonium accumulation and senescence of detached rice leaves caused by excess copper

The possibility that ammonium (NH ₄ ⁺ ) accumulation is linked to the senescence of detached rice (Oryza sativa) leaves induced by copper (Cu) was investigated. CuSO₄ was effective in promoting senescence of detached rice leaves. Both CuSO₄ and CuCl₂ induced NH ₄ ⁺ accumulation in detached rice leaves, indicating that NH ₄ ⁺ accumulation is induced by copper. Sulfate salts of Mg, Mn, Zn, and Fe were ineffective in inducing NH ₄ ⁺ accumulation in detached rice leaves. The senescence of detached rice leaves induced by Cu was found to be prior to NH ₄ ⁺ accumulation. Free radical scavengers, such as glutathione and thiourea, inhibited senescence caused by Cu and at the same time inhibited Cu-induced NH ₄ ⁺ accumulation. The current results suggest that NH ₄ ⁺ accumulation is not associated with senescence induced by Cu, but is part of the overall expression of oxidative damage caused by an excess of Cu. Evidence was presented to show that copper-induced ammonium accumulation in detached rice leaves is attributed to a decrease in glutamine synthetase activity and an increase in reduction of nitrate.     

Effects of copper on the growth,photosynthesis and nutrient concentrations of Phaseolus plants

Bean plants (Phaseolus vulgaris L. var. Zargana Kavala) were grown under conditions of increasing Cu concentrations in the growth medium (0.5-160.5 µM). Generally, the Cu concentrations between 0.5-1.5 µM were deficient, 1.5-10.5 µM were optimal, and 10.5-160.5 µM were toxic to plant growth. The Cu toxicity was associated with marked increases in plant tissue Cu concentrations. Under the Cu-deficient and optimal growth conditions, Cu was located primarily in the leaves. Under Cu toxicity, it was primarily sequestered in the roots. With increasing Cu in the growth medium, there was a positive correlation between Cu concentrations in the roots, stems and leaves, Ca in the roots, and K and Mg in the leaves. In contrast, Ca concentrations in the leaves and stems showed a negative correlation. The chlorophyll (Chl) concentration increased with increasing leaf Cu concentration, however, the Chl a/b ratio decreased. Since with an increasing leaf Cu concentration the leaf area decreased more markedly than the leaf dry mass, the net photosynthetic rate (PN) per leaf area increased and per dry mass decreased. The increase in PN per leaf area was almost entirely accounted for by the increase in Chl concentration. The initial Chl fluorescence (F0) increased with increasing leaf Cu concentration. The ratio of variable to maximum fluorescence (Fv/Fm) under Cu toxicity decreased. The half-time for the rise from F0 to Fm (t1/2) remained relatively unchanged with increasing leaf Cu concentration. Therefore the Cu-stress caused a small decrease in the efficiency of photosystem 2 photochemistry, but its primary effect was on growth.     

Copper tolerance in the cuprophyte Haumaniastrum katangense (S. Moore) P.A. Duvign. & Plancke

Cu tolerance and accumulation have been studied in Haumaniastrum katangense, a cuprophyte from Katanga (DR Congo), previously described as a copper hyperaccumulator. Nicotiana plumbaginifolia, a well-known non-tolerant and non-accumulator species, was used as a control. The germination rate of H. katangense was enhanced by copper and fungicide addition, suggesting that fungal pathogens, which restrain germination in normal conditions, are limiting. In hydroponic culture in the Hoagland medium, H. katangense did not grow well, in contrast to N. plumbaginifolia. Better growth was achieved by adding fungicide or higher copper concentrations. The maximal non-effective concentration (NEC) was 12 µM CuSO₄ for H. katangense grown in hydroponics, i.e. 24 times greater than Cu concentration in the Hoagland medium. By comparison, copper concentrations greater than 0.5 µM had a negative effect on the growth of N. plumbaginifolia. EC₅₀ (50% effective concentration) in hydroponics was 40 µM CuSO₄ for H. katangense and 6 µM CuSO₄ for N. plumbaginifolia. EC₁₀₀ (100% effective concentration) was 100 µM CuSO₄ for H. katangense and 15 µM CuSO₄ for N. plumbaginifolia. In soil, growth was also stimulated by Cu addition up to 300 mg kg^-1 CuSO₄. Surplus copper was also required for cultivating H. katangense in sterile conditions, suggesting that Cu excess may be necessary for needs other than pathogen defence. Cu accumulation in the shoot has been measured for N. plumbaginifolia and H. katangense at their respective NEC. Cu allocation in the two species showed a similar response to increasing Cu concentrations, i.e. root/shoot concentration ratio well above 1. In conclusion, H. katangense is highly tolerant to copper and has elevated copper requirement even in the absence of biotic interactions. Its accumulation pattern is typical of an excluder species.     

Soil microbial biomass, nutrient availability and nitrogen mineralization potential among vegetation-types in a low arctic tundra landscape

Copper uptake, localisation and biochemical and physiological traits were studied in hydroponically-grown Erica andevalensis plants at different increasing concentrations of Cu (1 µM, 50 µM, 100 µM, 250 µM, and 500 µM). Increasing Cu concentration in the nutrient medium led to a significative reduction in plant growth rate, an increase in root Cu concentration, leaf photosynthetic pigments and root peroxidase activity. Copper accumulation followed the pattern roots>stems>leaves, a typical behaviour of metal-excluders. Copper treatments led to significant changes in the free amino acid composition in shoots and roots and the concentration of polyamines in shoots. Analysis by scanning electron microscopy coupled with elemental X-ray analysis (SEM–EDX) showed a partial restriction of upward Cu transport by root vascular tissues. In leaf tissues, Cu mostly accumulated in the abaxial epidermis, suggesting a mechanism of compartmentalization to restrict mesophyll accumulation. The toxic effects of excess Cu were avoided to a certain extent by root immobilization, tissue compartmentalization, synthesis of complexing amino acids and induction of enzymes to prevent oxidative damage are among mechanisms adopted by Erica andevalensis to thrive in acidic-metalliferous soils.     

Ecofriendly Heavy Metal Stabilization: Microbial Induced Mineral Precipitation (MIMP) and Biomineralization for Heavy Metals within the Contaminated Soil by Indigenous Bacteria

Heavy metals (HMs) pollution is a serious problem, worldwide. The present study focuses on HMs removal (HMs mobility restricted within soil) by microbial induced mineral precipitation (MIMP) using indigenous isolates. Indigenous isolates were identified as Bacillus subtilis C(225)(MK334652), Oceanobacillus indicireducens 5(225)(MK334653), and Bacillus pumilus 7(225)(MK334654) by 16S-rRNA from HMs polluted industrial-soil (soil-225) that is used for bioremediation. The studied soil contained high level (mg/kg) of Cr(307.41?±?1.02), Cu(576.35?±?1.02), and Zn(708.81?±?1.50) as per Taiwan permissible limit (TPL) and/or Canadian Soil Quality Guidelines (CSQG). Minimum inhibitory concentration (MIC) of Bacillus species were higher compare to Oceanobacillus. Bioavailable-fraction (F₁) of HMs (Cr/Cu/Zn) in untreated 225-soil was noticed to be higher compared to F₂–F₅ fraction. Bacillus subtilis C(225) are more efficient for HMs-mineralization, compared to other isolates where Cr/Cu/Zn immobilized within soil, transforming from bioavailable-fraction (F₁) (high-mobility) (60–90% reduction) to residual-fraction F₅ (low-mobility) (50–80% increment). Organic-bound-fraction (F₄) (medium-mobility) of Cr increased (42.66?±?2.1%), compared to Cu/Zn, by Bacillus subtilis C(225). Urease (40.8%) and dehydrogenase (8.3%) activity increased in bio-remediated soil, compared to control. MIMP of HMs by ingenious bacteria reflects the transformation-pathway from F₁ to F₅ of HMs to fix strongly within soils with inadequate mobility. Thus, MIMP by indigenous microbe can be applicable for HMs stabilization/removal in contaminated soil for ecofriendly environmental cleanup.     

Copper,Zinc and Molybdenum in Livers of Norwegian Cattle At Slaughter

The concentrations of copper, zinc and molybdenum were measured in samples of cattle liver from 10 slaughter-houses in Norway. A total of 335 samples were analysed. A clear accumulation of copper with age was found, the average copper level in the younger animals (≦ 3 years, n = 194) being 30 µg Cu/g liver wet weight, and in the older ones (> 3 years, n = 141) 59 µg Gu/g. The range in the copper values found was considerable, though significant differences between some of the districts were recorded. Copper concentrations were classified as low (≦10 µg Gu/g) in 9.6 % of the samples. Zinc showed no accumulation with age, nor were there any differences in zinc levels found in animals from different districts, the average level being 32 µg Zn/g liver wet weight. The picture was the same for molybdenum, no differences between age groups or districts being found. The average level was 1.0 µg Mo/g liver. There was no significant correlation between levels of copper, zinc or molybdenum. The supply of copper and zinc to cattle in Norway seems close to sufficient, but copper- and zinc-fortified mineral supplementation of cattle feed is still to be recommended. There seems to be no need for molybdenum supplementation in cattle.     

Accumulation of low-molecular-weight organic acids in roots and leaf segments of Zea mays plants treated with cadmium and copper

Maize seedlings grown in a nutrient solution were treated with Cd (50, 100 µM) or Cu (50, 100 µM). Roots and separated leaf sections (from the youngest––basal, through the middle––mature, to the oldest––apical) were analysed. Shoot and root fresh weight, and root net growth rates were reduced significantly after Cu application in comparison to Cd. Copper (50, 100 µM) and cadmium (100 µM) decreased the sum of chlorophyll and total carotenoid pools mostly in mature and old leaf sections. The concentration of Cu and Cd increased in the old and mature leaf sections. Analysis of organic acids showed that both metals differently influenced the low-molecular-weight organic acids (LMWOAs) content in maize leaf sections. In mature sections, the excess Cu increased the succinate and tartrate contents, whereas in the young ones mainly the tartrate level was elevated. Cadmium elevated citrate accumulation in mature and old sections, compared to the control plants. Malate, the main LMWOA in maize leaves, increased only after addition of 100 µM of Cd (mature and old sections) or 50 µM of Cu (old sections). Analysis of LMWOAs in roots showed that the excess of Cd or Cu induced higher accumulation of tartrate and malate and, additionally, copper increased the citrate content.     

Zinc ameliorates copper-induced oxidative stress in developing rice (Oryza sativa L.) seedlings

Rice (Oryza sativa L.) seedlings were treated with different concentrations of copper (Cu) either in presence or absence of zinc (Zn), and different events were investigated to evaluate the ameliorative effect of Zn on Cu stress. In presence of high Cu concentration, growth of both root and shoots were considerably reduced. Decline in elongation and fresh mass was observed in root and shoot. Zn alone did not show any considerable difference as compared to control, but when supplemented along with high concentration Cu, it prompted the growth of both root and shoot. After 7 days, root growth was 9.36 and 9.59 cm, respectively, at 200 and 500 μM of Cu alone as compared to 10.59 and 12.26 cm at similar Cu concentrations, respectively, in presence of Zn. Cu accumulation was considerably high after 7 days of treatment. In absence of Zn, significant accumulation of Cu was observed. Zn supplementation ameliorated the toxic impact of Cu and minimized its accumulation. Cu treatment for 1 and 7 days resulted in a dose-dependent increase in hydrogen peroxide (H₂O₂). When Cu was added in presence of Zn, the H₂O₂ production in root and shoot was reduced significantly. The increase in H₂O₂ production under Cu stress was accompanied by augmentation of lipid peroxidation. In absence of Zn, Cu alone enhanced the malondialdehyde (MDA) production in both root and shoot after 1 and 7 days of treatment. The MDA content drastically reduced in root and shoot as when Zn was added during Cu treatment. The activities of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPX) were elevated under Cu stress both in root and shoot. Addition of Zn further stimulated the activities of these enzymes. Both ascorbate (AsA) and glutathione (GSH) contents were high under Cu stress either in presence or absence of Zn. The results suggests that Zn supplementation improves plant survival capacity under high Cu stress by modulating oxidative stress through stimulation of antioxidant mechanisms and restricts the accumulation of toxic concentrations of Cu.     

Characterization of cadmium concentration and translocation among ramie cultivars as affected by zinc and iron deficiency

Zn and Fe are essential nutritional elements in plants and play important roles in various physiological processes of plants. Zn and Fe are chemically similar to cadmium (Cd); therefore, Zn and Fe may mediate Cd-induced physiological or metabolic changes in plants. In order to evaluate the interaction between Cd, Zn and Fe, we conducted a hydroponics experiment to determine the plant biomass, photosynthetic characteristics, and Cd accumulation of ten ramie cultivars under Zn/Fe-sufficient or Zn/Fe-deficient conditions in the presence of 32 µM CdCl₂. Ramie varied among cultivars in morpho-physiological response to Cd stress as well as Cd accumulation, translocation and distribution. Zn and Fe deficiency increased the concentration and amount of Cd in plant organs, but decreased TF_{stem to leaf} and TF_{root to stem}. Cultivars with more Cd in roots and shoots showed smaller increase in Cd accumulation under Zn and Fe-deficiency stress. Xiangzhu 7 and Duobeiti 1 showed a higher capacity of Cd accumulation in their shoots. Zn and Fe deficiency decreased Pn, but increased Ci, Gs, and E in most cultivars. The difference in Cd translocation among ramie cultivars was mainly ascribed to the difference in plant transpiration.     

Leaf proteome characterization in the context of physiological and morphological changes in response to copper stress in sorghum

Copper (Cu) is an essential micronutrient required for normal growth and development of plants; however, at elevated concentrations in soil, copper is also generally considered to be one of the most toxic metals to plant cells due to its inhibitory effects against many physiological and biochemical processes. In spite of its potential physiological and economical significance, molecular mechanisms under Cu stress has so far been grossly overlooked in sorghum. To explore the molecular alterations that occur in response to copper stress, the present study was performed in ten-day-old Cu-exposed leaves of sorghum seedlings. The growth characteristics were markedly inhibited, and ionic alterations were prominently observed in the leaves when the seedlings were exposed to different concentrations (0, 100, and 150 µM) of CuSO₄. Using two-dimensional gels with silver staining, 643 differentially expressed protein spots (≥1.5-fold) were identified as either significantly increased or reduced in abundance. Of these spots, a total of 24 protein spots (≥1.5-fold) from Cu-exposed sorghum leaves were successfully analyzed by MALDI-TOF-TOF mass spectrometry. Of the 24 differentially expressed proteins from Cu-exposed sorghum leaves, 13 proteins were up-regulated, and 11 proteins were down-regulated. The abundance of most identified protein species, which function in carbohydrate metabolism, stress defense and protein translation, was significantly enhanced, while that of another protein species involved in energy metabolism, photosynthesis and growth and development were severely reduced. The resulting differences in protein expression patterns together with related morpho-physiological processes suggested that these results could help to elucidate plant adaptation to Cu stress and provide insights into the molecular mechanisms of Cu responses in C₄ plants.     

Copper Uptake and Its Effect on Metal Distribution in Root Growth Zones of Commelina communis Revealed by SRXRF

To explore the copper uptake mechanisms by the Cu-tolerant plant Commelina communis, the contents of Cu and other metals (including Fe, Zn, and Mn) in roots were detected using atomic absorption spectrometer under transporter inhibitors, partial element deficiency, or Cu excess treatments, while distribution characters of Cu and other metals in root growth zones were investigated by synchrotron radiation X-ray fluorescence spectroscopy (SRXRF). Cu uptake was inhibited by the uncoupler DNP and P-type ATPase inhibitor Na₃VO₄, not by the Ca²⁺ ion channel inhibitor LaCl₃, suggesting that Cu could probably be assimilated actively by root and be related with P-type ATPase, but not through Ca²⁺ ion channel. Fe or Zn deficiency could enhance Cu uptake, while 100 μM Cu inhibited Fe, Zn, and Mn accumulation in roots significantly. Metal distribution under 100 μM Cu treatment was investigated by SRXRF. High level of Cu was found in the root meristem, and higher Cu concentrations were observed in the vascular cylinder than those in the endodermis, further demonstrating the initiative Cu transport in the root of C. communis. Under excess Cu stress, most Fe was located in the epidermis, and Fe concentrations in the endodermis were higher than those in the vascular cylinder, suggesting Cu and Fe competition not only in the epidermal cells but also for the intercellular and intracellular transport in roots. Zn was present in the meristem and the vascular cylinder similar to Cu. Cu and Zn showed a similar pattern. Mn behaves as Zn does, but not like Fe.     

Concentration Levels of Essential and Non-essential Metals in Ethiopian Khat (Catha edulis Forsk)

The levels of essential (Ca, Mg, Mn, Fe, Zn, Cr, Cu, and Co) and non-essential (Cd and Pb) metal in six different varieties of Ethiopian khat (Catha edulis Forsk, an evergreen stimulant plant) commonly consumed in the country and exported to the neighboring countries were determined by flame atomic absorption spectrometry. Known weight of oven-dried khat samples were wet-digested using 2 mL of (69–72%) HNO₃ and 2 mL of (70%) HClO₄ for 2 h and 30 min at variable temperature (120–270°C). The mineral contents in the digests were analyzed using flame atomic absorption spectrometer. The following concentrations ranges in fresh-weight basis were recorded in decreasing order: Ca (1,038–2,173 µg/g)?>?Mg (478.2–812.3 µg/g)?>?Fe (53.95–82.83 µg/g)?>?Zn (5.18–9.40 µg/g)?>?Mn (6.98–8.66 µg/g)?>?Cu (1.85–5.53 µg/g)?>?Cr (0.66–3.47 µg/g)?>?Co (0.41–0.80 µg/g). A wide variation in the mineral contents of khat from different region of Ethiopia was noticed. The toxic metals (Pb and Cd) were not detected in all the samples analyzed.     

Effect of copper excess in environment on soybean root viability and morphology

The effects of increase copper concentrations in medium (10–150 μM CuSO₄) on growth and viability of the roots of two-week-old soybean seedlings (Glycine max L., cv. Dorintsa) were studied. Copper excess suppressed biomass accumulation and linear plant growth; copper affected root growth much stronger than shoot growth. The presence of 10 μM CuSO₄ in medium suppressed accumulation of plant biomass by 40% and the root length by 70%; in the presence of 25 μM CuSO₄, these indices were equal to 80 and 90%, respectively. In the presence of 50 μM CuSO₄, roots ceased to grow but biomass and shoot length still increased slightly. 150 μM CuSO₄ was lethal for plants. The earliest sign of excessive copper toxicity was the accumulation of MDA, indicating activation of membrane lipid peroxidation. A significant increase in MDA content was observed at plant incubation in medium with 10 μM CuSO₄ for 1 h; in this case, the content of copper in the roots increased from 36 ±1.8 (in control) to 48 ± 2.4 μg/g dry wt. The number of dead cells (permeable for the dye Evans Blue) was doubled in the presence of 200 μg/g dry wt within the root; this occurred in 72 h of growth in medium with 10 μM CuSO₄, in 6 h at 25 μM CuSO₄, in 3 h at 50 μM CuSO₄, and 1 h at 150 μM CuSO₄. Toxicity of copper excess was manifested stronger in dividing and elongation cells of the root apex (root meristem and the zone of elongation) than in more basal root regions. Copper excess resulted in the formation of breaks in the surface cell layers of the root tips and affect root morphology. When plant grew in medium with 10 μM CuSO₄, a distance of lateral root formation zone from the root tip decreased markedly, and spherical swellings were formed on the tips of lateral roots. The higher copper concentrations (50 and 150 μM) suppressed completely the development of lateral roots.     

Monitoring Copper Bioaccumulation in Cocoa from Copper-Based Pesticide–Treated Cocoa Farms Using Fuzzy Similarity Method

Cocoa production has been hindered by pests, leading to application of pesticides. These pesticide applications have raised health concerns. This study is therefore aimed at developing accumulation classifications for copper (Cu) in cocoa from plantations where Cu-based pesticides have been applied using fuzzy similarity method (FSM). Cocoa pods, seeds, leaves, and soil samples were collected from five different plantations from three states in Nigeria. The plant samples were digested using standard methods, whereas the Cu in soil samples was extracted with 1 M ammonium acetate. The products were analyzed for Cu using flame atomic absorption spectrophotometer. The Cu concentrations obtained were used to model the accumulation degree using FSM. The Cu concentrations were higher in the leaves than the seeds and the pods. The persistency of Cu was displayed by high concentrations (11.5–375 mg/kg) and enrichment factor in CRIN sites where this pesticide application has been stopped for over a decade. The leaves from Ondo sites had the highest Cu concentration, which indicates impact of recent applications. The FSM membership function and algorithm indicated that the plant parts had low degrees of accumulation for fresh leaves, pods, and seeds, the valued part applied in beverages, but for the dry leaves, the accumulation degree is high. It may be concluded that the applied Cu-based pesticide had more impact and accumulation on the leaves than the commercial valued seeds, but the Cu concentration in the seeds is above the recommended value.     

Enhanced Soil Washing for the Remediation of a Brownfield Polluted by Pyrite Ash

Soil from an abandoned/disused fertilizer plant polluted with pyrite ash containing heavy metal(loid)s (As, Cu, Pb, and Zn) was treated by means of physical and chemical washing. We first performed an exhaustive characterization of the soil-pollutant interaction, which allowed us to determine the chemical nature (complex oxyhydroxides), potential mobility and bioavailability of the pollutants (very low), as well as the grain size fractions of preferential accumulation (silt-clay fraction comprises more than 60% of the material and revealed contents well above 2.000 ppm of Cu, Zn and Pb). Soil/ash samples were subjected to a number of chemical washing trials, including leaching with 2 M HCl, 2 M NaOH and acidic process water (pH around 0). The fraction below 63 µm was mechanically separated and exposed to additional leaching tests e.g. chloridizing roasting with NaCl plus water leaching. Of all the tested procedures, the latter proved the most effective, particularly with regard to Cu and Zn recovery (recoveries up to 40% and 34%, respectively). The information gathered offers an insight into the modes and rates at which metals can be leached from pyrite ashes after chloridizing roasting as a prelude to more extensive soil washing feasibility studies focused on potential metal recovery.     

Copper uptake by Pteris melanocaulon Fée from a Copper-Gold mine in Surigao del Norte,Philippines

The ability of some plants to take up metal contaminants in the soil has been of increasing interest as an environmental approach to pollution clean-up. This study aimed to assess the ability of Pteris melanocaulon for copper(Cu) uptake by determining the Cu levels in the fern vis-à-vis surrounding soil and the location of Cu accumulation within its biomass. It also aimed to add information to existing literature as P. melanocaulon are found to be less documented compared to other fern metal accumulators, such as P. vittata. The P. melanocaulon found in the Suyoc Pit of a Copper-Gold mine in Placer, Surigao del Norte, Philippines exhibited a high Bioaccumulation Factor(BF) of 4.04 and a low Translocation Factor(TF) of 0.01, suggesting more Cu accumulation in the roots (4590.22 ± 385.66µg g^?1 Cu). Noteworthy was the Cu concentration in the rhizome which was also high (3539.44 ± 1696.35µg g^?1 Cu). SEM/EDX analyses of the Cu content in the roots indicated high elemental %Cu in the xylem (6.95%) than in the cortex (2.68%). The high Cu content in the roots and rhizomes and the localization of Cu in the xylem manifested a potential utilization of the fern as a metallophyte for rhizofiltration and phytostabilization.     

Involvement of zinc in intracellular oxidant/antioxidant balance

The effect of zinc (Zn) on cellular oxidative metabolism is complex and could be explained by multiple complementary interactions. In this study, we evaluated the impact of Zn on the pro-oxidant/ antioxidant balance of HaCaT keratinocytes. Cells were submitted to a diffusible metal chelator able to induce intracellular Zn deprivation, TPEN, in combination or not with Zn chloride (ZnCl₂), in the culture medium. The intracellular amount of Zn, copper (Cu), and iron (Fe) was determined, as well as CuZnSOD and MnSOD activities and glutathione reserves. The consequence of the modulation of Zn concentration on lipid peroxidation was also evaluated. TPEN induced a significant dose-dependent decrease in intracellular Zn and Cu (from 394–181 and 43–21 Μg/g protein, respectively, after 6 h of TPEN 50 ΜM). No significant change in intracellular Fe concentration was found following TPEN exposure. The SOD activities were unchanged after 6 h of TPEN 50 ΜM application, either CuZnSOD or MnSOD. Cells exposure to TPEN induced a deep time- and dosedependent decrease in their glutathione content (from 65–8 ΜM/g protein after 6 h of TPEN 50 ΜM), and a concomittant increase in glutathione in the cell-culture supernatants. No significant change in lipid peroxidation products was detected.