How do different concentrations of aluminum and zinc affect the survival, body size, morphology and immune system of Physalaemus cuvieri (Fitzinger, 1826) tadpole?

The assessment of amphibian responses as bioindicators of exposure to chemical pollutants is an important tool for conservation of native species. This study aimed to investigate the effects of chronic aluminum (Al) and zinc (Zn) exposure on survival, body size, morphology (malformations), and immune system (leukocyte profile) in P. cuvieri tadpoles. Ecotoxicological analyses were performed utilizing chronic toxicity tests in which 210 tadpoles at the 25th Gosner developmental stage were exposed to Al and Zn. Individuals of P. cuvieri were maintained in glass containers containing various concentrations of aluminum sulfate (0.1, 0.2, or 0.3 mg/L) and zinc sulfate (0.18, 0.27 or 0.35 mg/L), and tests were performed in triplicate. After 14 days, amphibians were weighed, measured and survival rate, malformations in the oral and intestine apparatus, leukocyte profile, and ratio between neutrophils and lymphocytes determined. The differing concentrations of Al and Zn did not produce lethality in P. cuvieri where 95% of the animals survived 326 hr following metal exposure. Individuals exposed to Zn achieved greater body growth and weight gain compared to controls. Aluminum increased weight gain compared controls. These metals also produced malformations of the oral and intestine apparatus and enhanced occurrence of hemorrhages, especially at the highest doses. Lymphocytes were the predominant cells among leukocytes, with lymphopenia and neutrophilia observed following Al and Zn treatment, as evidenced by elevated neutrophil/lymphocyte ratio, an important indicator of stress in animals. Data suggest that further studies need to be carried out, even with metal concentrations higher than those prescribed by CONAMA, to ensure the conservation of this species.

Screening of tolerance of Atriplex vulgatissima under zinc or lead experimental conditions. An integrative perspective by using the integrated biological response index (IBRv2).

The search for plants with a high capacity to tolerate and accumulate metals is an important issue in phytoremediation. In this sense, this study was conducted in the halophyte Atriplex vulgatissima to evaluate the effects of different concentrations of lead (Pb, 50 and 100 µM) or zinc (Zn, 100 and 200 µM) on morphological, physiological, and biochemical parameters as well as the accumulation patterns of this species. The results indicated that while essential metal Zn showed high translocation from roots to shoots (TF > 1), non-essential Pb was mainly accumulated in the roots (BCF>1). Regarding shape, both metals induced slenderness of the blade, but only Zn treatment reduced leaf size. No difference in biomass production and photosynthetic parameters was found between Pb and Zn treatments. Pb treatments did not show significant differences between treatments regarding water content (WC), pigment concentration, and the activity of superoxide dismutase (SOD) and guaiacol peroxidase (GPx), but did result in a decrease in catalase activity at 100 µM Pb. On the other hand, 200 µM Zn leads to a clear reduction in WC and pigment concentrations, along with an increase in SOD and GPx activities. In addition, ascorbate peroxidase (APx) activity showed a hormesis effect at 50 µM Pb and 100 µM Zn. Malondialdehyde increased with both Pb and Zn treatments. The integrated biological index (IBRv2) indicated that 200 µM Zn was the most affected treatment (IBRv2 = 19.02) and that under the same concentrations of metals (100 µM Pb or Zn), Pb treatments presented major stress (IBRv2 = 11.55). A. vulgatissima is a metallophyte with the potential for Pb phytostabilization and Zn phytoextraction, as well as a bioindicator of these metals. Its high biomass and deep roots, combined with its halophytic traits, make it suitable for bioremediation and monitoring programs.

Proposal of a chronic toxicity test using the tropical epibenthic amphipod Parhyale hawaiensis.

Chronic toxicity tests with representative organisms are essential for ecological risk assessment. The circumtropical marine amphipod Parhyale hawaiensis is a promising test organism in ecotoxicology. This study aimed to develop a chronic toxicity protocol for liquid samples testing with P. hawaiensis using reproduction and growth as endpoints. In the proposed protocol, organisms (≤52 days old) are placed in 5 replicates each containing 100 mL of solution, 10 organisms, and 5 g of crushed coral for 42 days of exposure. The protocol was successfully developed but reproduction showed better performance than growth rate. NOECs based on reproduction were determined for zinc (0.10 mg Zn L-1) and 3,4-DCA (0.50 mg L-1), and they are of the same order of magnitude compared with the values of other amphipods. The developed test based on reproduction can be considered a promising tool for hazard characterizations although more tests with different substances are still needed.

Effects of cadmium and zinc on gene expression of novel molecular biomarkers in the mangrove oyster Crassostrea gasar.

Metal contamination impacts various aquatic species, and mollusk bivalves are appropriate sentinel organisms in coastal pollution assessment. Metal exposure can disrupt homeostasis, alter gene expression, and harm cellular processes. However, organisms have evolved mechanisms to regulate metal ions and counteract their toxicity. This study examined the effect of acute cadmium (Cd) and zinc (Zn) on metal-related gene expression in gills of Crassostrea gasar following 24 and 48 h of laboratory exposure. We focused on Zn transport, metallothionein (MT), glutathione (GSH) biosynthesis, and calcium (Ca) transporter genes to understand the underlying Cd and Zn-accumulating mechanisms that prevent metal toxicity. Our findings revealed increased Cd and Zn levels in oyster gills, with significantly higher accumulation after 48 h. C. gasar accumulated high Cd concentrations even in scarce conditions and increased Zn levels, suggesting a strategy to cope with toxicity. While no significant gene expression differences were observed after 24 h, the increased metal accumulation after 48 h led to upregulation of CHAC1, GCLC, ZnT2, and MT-like genes in oysters exposed to Cd, and increased ZnT2-like expression following exposure to higher Cd/Zn mixtures. We found evidence of oysters may mobilize metal-related genes to mitigate Cd-induced toxicity by both chelating metals and/or reducing their intracellular concentrations. The observed genes upregulation also indicates their sensitivity to changes in metal bioavailability. Overall, this study offers insights into oyster mechanisms for coping with metal toxicity and suggests ZnT2, MT, CHAC1, and GCLC-like as molecular biomarkers for monitoring aquatic metal pollution using C. gasar as sentinel species.

Iron counteracts zinc-induced toxicity in soybeans.

Zinc (Zn) and iron (Fe) are essential micronutrients for all living organisms and the major targets for crop biofortification. However, when acquired in excess quantities, Zn and Fe can be toxic to plants. In this study, we examined the interaction between Zn and Fe in soybean plants under various Zn and Fe treatments. While the level of Zn accumulation increased with increasing Zn supplies, Zn content greatly decreased with rising Fe supplies. Moreover, Zn uptake rates were negatively correlated with Fe supplies. However, Fe accumulation was not greatly affected by elevating Zn supplies. Excess Zn supplies were found to induce typical Fe deficiency symptoms under low Fe conditions, which can be counteracted by increasing Fe supplies. Interestingly, leaf chlorosis caused by excess Zn and low Fe supplies was not directly associated with reduced total Fe content but likely associated with deleterious effects of excess Zn. The combination of high Zn and low Fe greatly activates FRO2 and FIT1 gene expression in soybean roots. Besides, Zn-Fe interaction influences the activities of antioxidative enzymes as well as the uptake, accumulation, and homeostasis of other essential micronutrients, such as copper and manganese in soybean plants. These findings provide new perspectives on Zn and Fe interaction and on heavy metal-induced Fe deficiency-like symptoms.

Bio-efficacy of iron and zinc fortified wheat flour along with bio-assessment of its hepatic and renal toxic potential.

Study was planned to assess the bio-efficiency along with toxicity of iron and zinc fortified whole wheat flour in Sprague dawley albino rats. Whole wheat flour was fortified with different dosage of sodium iron EDTA (NaFeEDTA), ferrous sulphate (FeSO4), zinc oxide (ZnO) and zinc sulphate (ZnSO4). The rats (n=3) in each group were fed on fortified wheat flour for 2 months. Liver biomarkers including alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate aminotransferase (AST) and bilirubin were recorded from serum samples. Increased concentration of ZnSO4 affected the liver biomarkers to be highest among all whereas, bilirubin levels were less than the rats fed on control diet. The above mentioned fortificants have negligible effect on renal biomarkers including creatinine and urea. Moreover, hematological parameters were also checked and reportedly, sodium iron EDTA fed rats presented highest amount of hemoglobin, iron and total iron binding capacity. Highest zinc level was observed in rats fed on whole wheat flour fortified with 60mg/Kg Zinc oxide. Microscopic observation of liver tissue depicted that rats fed on iron and zinc fortified wheat flour have more toxic effects whereas, histopathology presentation of kidney tissue has least toxic impact. It has been concluded that mandatory fortification of wheat flour with iron and zinc may cause increased serum biomarkers along with toxicity of vital organs like liver, hence fraction of wheat flour may be fortified to fulfill the requirements of deprived and vulnerable group.

Bioaccumulation of heavy metals in the tissues of Schizothorax plagiostomus at River Swat / Bioacumulação de metais pesados nos tecidos de Plagiostomo esquizotórax em River Swat

Snow trout (Schizothorax plagiostomus) is an economically important freshwater fish, mostly found in northern areas of water reservoirs of Pakistan. The current study was conducted in River Swat to analyze the bioaccumulation of heavy metals (Pb, Cr, Ni, and Zn) in tissues of Schizothorax plagiostomus. Tissues were extracted and dissolved in perchloric acid (HClO4) and nitric acid (HNO3) along with hotplate. The heavy metals, zinc (Zn), lead (Pb), chromium (Cr), and Nickel (Ni) were determined using Perkin Elmer 2380 atomic absorption spectrophotometer. Results shows great variation in the content of the metal related to tissue type and sampling sites. A high concentration of bioaccumulation was reported at Charbagh, whereas lowest at Odigram: Charbagh>Landakai>Odigram. In the same way, Cr was the most accumulated heavy metal followed by lead, nickel, and Zinc.(AU)

A truta das neves (Schizothorax plagiostomus) é um peixe de água doce economicamente importante, encontrado principalmente nas áreas ao norte de reservatórios de água do Paquistão. O presente estudo foi realizado em River Swat para analisar a bioacumulação de metais pesados (Pb, Cr, Ni e Zn) em tecidos de Schizothorax plagiostomus. Os tecidos foram extraídos e dissolvidos em ácido perclórico (HClO4) e ácido nítrico (HNO3) com placa de aquecimento. Os metais pesados zinco (Zn), chumbo (Pb), cromo (Cr) e níquel (Ni) foram determinados usando espectrofotômetro de absorção atômica Perkin Elmer 2380. Os resultados mostram grande variação no conteúdo do metal relacionado ao tipo de tecido e locais de amostragem. Uma alta concentração de bioacumulação foi relatada em Charbagh, enquanto a mais baixa, em Odigram: Charbagh > Landakai > Odigram. Da mesma forma, Cr foi o metal pesado mais acumulado, seguido por Pb, Ni e Zn.(AU)

Bioaccumulation of heavy metals in the tissues of Schizothorax plagiostomus at River Swat / Bioacumulação de metais pesados nos tecidos de Plagiostomo esquizotórax em River Swat

Snow trout (Schizothorax plagiostomus) is an economically important freshwater fish, mostly found in northern areas of water reservoirs of Pakistan. The current study was conducted in River Swat to analyze the bioaccumulation of heavy metals (Pb, Cr, Ni, and Zn) in tissues of Schizothorax plagiostomus. Tissues were extracted and dissolved in perchloric acid (HClO4) and nitric acid (HNO3) along with hotplate. The heavy metals, zinc (Zn), lead (Pb), chromium (Cr), and Nickel (Ni) were determined using Perkin Elmer 2380 atomic absorption spectrophotometer. Results shows great variation in the content of the metal related to tissue type and sampling sites. A high concentration of bioaccumulation was reported at Charbagh, whereas lowest at Odigram: Charbagh>Landakai>Odigram. In the same way, Cr was the most accumulated heavy metal followed by lead, nickel, and Zinc.

A truta das neves (Schizothorax plagiostomus) é um peixe de água doce economicamente importante, encontrado principalmente nas áreas ao norte de reservatórios de água do Paquistão. O presente estudo foi realizado em River Swat para analisar a bioacumulação de metais pesados (Pb, Cr, Ni e Zn) em tecidos de Schizothorax plagiostomus. Os tecidos foram extraídos e dissolvidos em ácido perclórico (HClO4) e ácido nítrico (HNO3) com placa de aquecimento. Os metais pesados zinco (Zn), chumbo (Pb), cromo (Cr) e níquel (Ni) foram determinados usando espectrofotômetro de absorção atômica Perkin Elmer 2380. Os resultados mostram grande variação no conteúdo do metal relacionado ao tipo de tecido e locais de amostragem. Uma alta concentração de bioacumulação foi relatada em Charbagh, enquanto a mais baixa, em Odigram: Charbagh > Landakai > Odigram. Da mesma forma, Cr foi o metal pesado mais acumulado, seguido por Pb, Ni e Zn.

Effect of phosphorus on the toxicity of zinc to the microalga Raphidocelis subcapitata.

The aim of this study was to evaluate the effect of phosphorus (P) on the toxicity of zinc (Zn) for the alga Raphidocelis subcapitata. P was provided in three concentrations: 2.3 x 10-4 mol L-1, 2.3 x 10-6 mol L-1 and 1.0 x 10-6 mol L-1. Algal cells were acclimated to the specific P concentrations before the start of the experiment. The chemical equilibrium software MINEQL+ 4.61 was employed to calculate the Zn2+ concentration. After acclimated, the algal cells were inoculated into media containing different Zn concentrations (0.09 x 10-6 mol L-1 to 9.08 x 10-6 mol L-1). The study showed that besides the reduction in algal growth rates, phosphorus had an important influence on the toxicity of zinc for microalga. The inhibitory Zn2+ concentration values for R. subcapitata were 2.74 x 10-6 mol L-1, 0.58 x 10-6 mol L-1 and 0.24 x 10-6 mol L-1 for the microalgae acclimated at P concentrations of 2.3 x 10-4 mol L-1, 2.3 x 10-6 mol L-1 and 1.0 x 10-6 mol L-1, respectively. Ecotoxicological studies should consider the interaction between metal concentrations and varying P values to provide realistic data of what occurs in phytoplankton communities in environments.

Phytotoxicity Increase Induced by Zinc Accumulation in Cichorium intybus.

The accumulation of zinc (Zn) in Cichorium intybus and effects of phytotoxicity during 90 days of growth on (natural) non-contaminated and Zn-contaminated soils were studied. The phytotoxicity effects were monitored by evaluating the leaf area, leaf biomass, leaf length and root length of the vegetable. The Zn concentrations ranged from 5.35 ± 1.05 to 37.5 ± 3.89 mg kg-1 in leaves of plants grown on natural soil, and from 334.0 ± 25.6 to 2232 ± 16.7 mg kg-1 when grown on Zn-contaminated soils. Zn accumulation caused a decrease in growth on contaminated soils and an increase in phytotoxicity. These effects were associated to high metal concentration, mobility and bioavailability in the soil as well as changes in the translocation mechanism from the roots to the leaves. Then, it must be avoided the organic fertilization of soils with either animal manure or other agricultural inputs containing high zinc concentrations.

Plants' genetic variation approach applied to zinc contamination: secondary metabolites and enzymes of the antioxidant system in Pfaffia glomerata accessions.

Zinc (Zn) is a micronutrient, but its excessive concentration can impair plant growth and development. Fertilizers, liming materials, pesticides and fungicides containing Zn have contributed to increase its concentration in agricultural soils. The aim of the present study is to evaluate the effect of Zn excess on the non-enzymatic (anthocyanin and ß-ecdysone) and enzymatic (superoxide dismutase-SOD and guaiacol peroxidase-GPX) antioxidant system of two P. glomerata accessions (JB and GD) grown in hydroponic system and soil, under short- and long-term exposure times. Three Zn levels (2, 100 and 200 µM) and two short-term exposure times (7 and 14 d) were tested in the hydroponic experiment. Three Zn levels (2, 100 and 200 mg kg-1) and two long-term exposure times (34 and 74 d) were tested in the soil experiment. The effects of Zn excess on P. glomerata accessions depended on the growth system and exposure time. Zinc excess in both tested growth systems resulted in significant change in the tissue oxidative process (MDA concentration) in both accessions, as well as broadened the antioxidant system response, which was based on antioxidant enzymes (SOD and GPX) and secondary metabolites (anthocyanins and ß-ecdysone). The highest anthocyanin concentration was observed in accession JB, which was grown in hydroponics, but tissue anthocyanin concentration increased in both accessions, regardless of growth medium and exposure time. The ß-ecdysone concentration in the roots increased in both accessions, but accession GD was more responsive to Zn excess. There was significant physiological variation in P.glomerata accessions in response to Zn excess.

Comparative ecotoxicity of single and binary mixtures exposures of cadmium and zinc on growth and biomarkers of Lemna gibba.

In the present study, single and mixture effects of cadmium (Cd) and zinc (Zn) on Lemna gibba were analyzed and compared using growth parameters, based on frond number and fresh weight, and biochemical parameters, such as pigment, protein content and activity of antioxidant enzymes. Plants were exposed for 7 days to these metals in nutrient solution. Single and mixture exposures affected plant growth and the biomarkers of the antioxidant response. Considering the growth parameters, Cd was found to be much more toxic than Zn. IC50-7d, based on growth rate calculated on frond number, were 17.8 and 76.73 mg/L, and on fresh weight were 1.08 and 76.93 mg/L, for Cd and Zn respectively. For Cd, LOEC values were obtained at 2.06 and 1.03 mg/L, for frond number and fresh weight respectively; while for Zn, at 20.1 and 74.6 mg/L. A high toxicity effect, considering the same response variables, was observed in plants exposed to the mixtures. Three fixed ratios, based on toxic units (TU) were assayed, ratio 1: 2/3 Cd-1/3 Zn, ratio 2: 1/2 Cd-1/2 Zn and ratio 3: 1/3 Cd-2/3 Zn. Ratio 3 (where Zn was added in higher proportion) was the less toxic. All concentrations of Ratio 1 and 2 significantly inhibited plant growth, showing a 100% inhibition of growth rate at the highest concentrations when based on frond number. Catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APOX; EC 1.11.1.11) and guaiacol peroxidase (GPOX; EC 1.11.1.7) activities in single metals assays were higher than controls. In mixture tests, the activity of APOX and GPOX was significantly stimulated in plants exposed to all evaluated combinations, while CAT was mainly stimulated in Ratio 3. It was observed that the activity of the enzymes was increased in the mixtures compared with similar concentrations evaluated individually. APOX activity was observed to fit the CA model and following a concentration-response pattern. The response of this antioxidant enzyme could serve as a sensitive stressor biomarker for Cd-Zn interactions. Frond number in Cd-Zn mixtures was not well predicted from dissolved metal concentration in solution using concentration addition (CA) as reference model, as results showed that toxicity was more than additive, with an average of ΣTU = 0.75. This synergistic effect was observed up to 50 mg Zn/L in the mixture, but when it was present in higher concentrations a less than additive effect was observed, indicating a protective effect of Zn. A synergistic and dose-ratio deviations from CA model were also observed.

Zinc toxicity in seedlings of three trees from the Fabaceae associated with arbuscular mycorrhizal fungi.

Due to diverse human activities zinc (Zn) may reach phytotoxic levels in the soil. Here, we evaluated the differential sensibility of three Brazilian tree species from the Fabaceae to increasing soil Zn concentrations and its physiological response to cope with excess Zn. A greenhouse experiment was conducted with the species: Mimosa caesalpiniaefolia, Erythrina speciosa and Schizolobium parahyba, and the addition of 0, 200, 400 and 600 mg Zn kg-1 to the soil. Plants were harvested after three months of cultivation, and growth, root symbiosis, biochemical markers and elemental composition were analyzed. Soil Zn addition reduced seedling growth, irrespective of the species, with a strong reduction in M. caesalpiniaefolia. Regarding root symbiosis, in N2-fixing species, nitrogenase activity was reduced by the highest Zn concentrations. Zn addition caused plants nutritional imbalances, mainly in roots. The content of photosynthetic pigments in leaves decreased up to 40%, suggesting that high Zn contents interfered with its biosynthesis, and altered the content of foliar polyamines and free amino acids, depending on the species and the soil Zn concentration. Zn toxicity in M. caesalpiniaefolia plants was observed at available soil Zn concentrations greater than 100 mg kg-1 (DTPA-extractable), being the most sensitive species and E. speciosa was moderately sensitive. S. parahyba was a moderately tolerant species, which seems to be related to polyamines accumulation and to mycorrhizal association. This last species has the potential for revegetation of areas with moderately high soil Zn concentration and for phytostabilization purposes. Future research evaluating the tolerance to multiple metal stress under field conditions should confirm S. parayba suitability in Zn contaminated areas of tropical regions.

Metabolic effects in the freshwater fish Geophagus iporangensis in response to single and combined exposure to graphene oxide and trace elements.

Graphene oxide (GO) is part of a new set of nanomaterials with particular characteristics related to its nanoscale size. Due to this feature, it presents high reactivity and other contaminants present in the environment could bind to them and affect its intrinsic toxicity. The metabolic effects of such nanomaterials and their combination with two common pollutants, zinc and cadmium, on the freshwater fish Geophagus iporangensis are analyzed. Moreover, metabolic rate and ammonia excretion were used as bioindicators to measure metabolic changes. Fishes were exposed for 24 h in filtered tap water to different concentrations of GO (0.5; 1.0; 2.0 and 4.0 mg L-1), Zn (0.5; 1.0; 2.0; 4.0 and 10.0 mg L-1) and Cd (0.1; 0.5; 1.0; 2.0 and 4.0 mg L-1). Combined effects were verified using the same concentrations of trace elements added to 1.0 mg L-1 of GO. Exposure to GO and Cd resulted in a decrease of metabolic rate in G. iporangensis, by about 30% compared to control means, in the highest concentration tested (4.0 mg L-1). However, zinc exposure in the highest concentration (10 mg L-1) raised metabolic rate to around three times that of the control group. Ammonia excretion was not affected by exposure to GO and Cd. In contrast, exposure to Zn at 10 mg L-1 raised the rate to around 47%. The combined exposure of GO and Zn intensified the effects of the trace element, inducing responses in both biomarkers at lower concentrations and demonstrating that the interaction between elements increases zinc's effects. The combination Cd + GO only affects metabolic rate. Thus, this metabolic rate alone reveals that combined exposure potentiates effects of trace elements on fish metabolism.

Advanced determination of the spatial gradient of human health risk and ecological risk from exposure to As, Cu, Pb, and Zn in soils near the Ventanas Industrial Complex (Puchuncaví, Chile).

The townships of Puchuncaví and Quintero, on the coast of central Chile, have soils contaminated by atmospheric deposition of sulfur dioxide and trace elements from the nearby Ventanas Industrial Complex. The purpose of this study was to evaluate potential human health and ecological risks, by determining the spatial distribution of soil total concentrations arsenic (As), copper (Cu), lead (Pb), and zinc (Zn) in these townships. Total concentrations of these elements were determined in 245 topsoil samples, used to generate continuous distribution maps. The background concentrations of Cu, As, Pb, and Zn in the studied soils were 100, 16, 35, and 122 mg kg-1, respectively. The concentrations of Cu, As, and Pb were positively correlated with each other, suggesting that their source is the Ventanas copper smelter. On the other hand, correlations for Zn were weaker than for other trace elements, suggesting low impact of the Ventanas copper smelter on spatial distribution of Zn. Indeed, only 6% of the study area exhibited Zn concentrations above the background level. In contrast, 77, 32 and 35% of the study area presented Cu, As, and Pb concentrations, respectively, above the background level. The carcinogenic risk due to exposure to As was above the threshold value of 10-04 in the population of young children (1-5 years old) on 27% of the study area. These risk values are classified as unacceptable, which require specific intervention by the Chilean government. Based on the estimated concentrations of exchangeable Cu, 10, 15, and 75% of the study area exhibited high, medium, and low phytotoxicity risk, respectively.

Effects of sublethal zinc ions and acute crude oil exposure on serum enzymes activity of Carassius gibelio

The current study was intended to investigate the responses of freshwater fish Carassius gibelio as an in vivo model by measuring the activity of the enzyme of the liver. Fish exposed to sub-lethal toxicities due to zinc metal and crude oil. Fish were treated to 0.6 and 1.2 mg/l for zinc ions as well as 500 and 2500 mg/l for crude oil during 96h, and the alterations in serum enzyme activities were determined aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Zinc toxicity elevated activity levelin hepatic enzymes in a significant way (P < 0.05). The present study appeared the slightly augmented levels of AST in the serum of C. gibelio when exposed to sub-lethal Zinc concentration while the serum ALT activity increased in response to the high level of Zn exposure when compared to control after (96 h). In addition, acute concentrations of crude oil after 96 h exposure can cause harmful effects on Carassius gibelio including the induction of (AST). However, not effecting found (ALT). We are concluded that changes in the activity of the enzyme can be considered as a pointer of the pollution impact in fish.

Effects of sublethal zinc ions and acute crude oil exposure on serum enzymes activity of Carassius gibelio

The current study was intended to investigate the responses of freshwater fish Carassius gibelio as an in vivo model by measuring the activity of the enzyme of the liver. Fish exposed to sub-lethal toxicities due to zinc metal and crude oil. Fish were treated to 0.6 and 1.2 mg/l for zinc ions as well as 500 and 2500 mg/l for crude oil during 96h, and the alterations in serum enzyme activities were determined aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Zinc toxicity elevated activity levelin hepatic enzymes in a significant way (P < 0.05). The present study appeared the slightly augmented levels of AST in the serum of C. gibelio when exposed to sub-lethal Zinc concentration while the serum ALT activity increased in response to the high level of Zn exposure when compared to control after (96 h). In addition, acute concentrations of crude oil after 96 h exposure can cause harmful effects on Carassius gibelio including the induction of (AST). However, not effecting found (ALT). We are concluded that changes in the activity of the enzyme can be considered as a pointer of the pollution impact in fish. (AU)

Single and Combined Effects of Zinc and Manganese on the Bivalve Anodontites trapesialis: Complementary Endpoints to Support the Hypothesis of Manganese Promoting Metabolic Suppression in Gills.

Manganese (Mn) might stimulate the valve closure reflex in the freshwater bivalve Anodontites trapesialis, leading to metabolic suppression, whereas zinc (Zn) is not able to modify this behavior. To investigate this particular response, we exposed A. trapesialis specimens to Mn (0.5 mg L-1 ) and Zn (1.0 mg L-1 ) alone, and to their mixture, to measure further endpoints in different clam tissues: glycogen level in gills, and calcium (Ca2+ ), sodium (Na+ ), and chloride (Cl- ) concentrations in the hemolymph. Furthermore, we used cutting-edge technology, proteomics, to evaluate modifications in protein patterns under the 3 exposure tests. The main results highlighted that only Mn caused a clear drop in glycogen levels in gills, an increase in Ca2+ and Na+ , and a simultaneous decrease in Cl- concentration in the hemolymph. The proteomic analysis confirmed that Mn promoted more effects in A. trapesialis than the other tested conditions, because the number of proteins modulated was higher than the results obtained after exposure to Zn and the mixture. Moreover, 11 of the 12 modulated proteins were down-expressed. These results consolidate the hypothesis that Mn might suppress gill metabolic rate in A. trapesialis. Environ Toxicol Chem 2019;38:2480-2485. © 2019 SETAC.

Comparative ecotoxicity of single and binary mixtures exposures of nickel and zinc on growth and biomarkers of Lemna gibba.

The aim of this study was to compare the ecotoxicity of nickel (Ni) and zinc (Zn) assayed as single and as binary mixture. In addition, how were affected the population growth rates and oxidative stress biomarkers, comparing single to binary exposures. The toxicity tests were performed on Lemna gibba using a 7-day test. All calculations were made using measured total dissolved metal concentrations. IC50-7d, based on growth rate calculated on frond number and fresh weight, were 2.47/3.89 mg/L, and 76.73/76.93 mg/L, for Ni and Zn, respectively. Single metals affected plant growth following a non-linear concentration-response relationship. LOEC values for each metal were obtained at 0.92 and 20.1 mg/L for Ni and Zn, respectively. Biomarkers of the antioxidant response like Catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APOX; EC 1.11.1.11) and guaiacol peroxidase (GPOX; EC 1.11.1.7) activities in single metals assays were higher than controls, but when similar concentrations were added as mixtures, that increase was reduced and inhibition with respect to the control was observed for GPOX. APOX showed the highest activity. The concentration addition (CA) approach was evaluated and resulted in a correct predictor of Ni-Zn mixture toxicity on Lemna gibba. This was made comparing the EC50 and LOEC, measured taking the growth rate as endpoint, with those expected values according to the CA model. However, the measured biomarkers indicating a positive response to free radicals did not fit to concentration addition model when assayed in the binary mixture. Also, the main activity response of these was observed within a range of concentrations below the LOEC values for the mixture.

Metal Toxicity During Short-Term Sediment Resuspension and Redeposition in a Tropical Reservoir.

Billings Complex is the largest water-storage reservoir in São Paulo, Brazil, and has been contaminated since the 1960s. Periodically, Billings sediments are subjected to currents causing resuspension and subsequent release of metals. A short-term (4-h) resuspension was simulated using sediment flux exposure chambers (SeFECs) to better understand the fate, bioavailability, and transport of iron (Fe), manganese (Mn), and zinc (Zn) during these events, as well as possible organism toxicity. Daphnia magna and Hyalella azteca were exposed during the 4-h resuspension, and were monitored after exposure for survival, growth, and reproduction. Resuspension rapidly deoxygenated the overlying water, decreased the pH, and resulted in elevated dissolved Zn above the US Environmental Protection Agency's (2002) criteria for acute toxicity (120 µg L-1 ). However, Zn was scavenged (after 20 h) from solution as new sorption sites formed. Dissolved Mn increased during and after resuspension, with maximum values at 20 h post exposure. An initial release of Fe occurred, likely associated with oxidation of acid-volatile sulfides, but decreased after 1 h of resuspension. The Fe decrease is likely due to precipitation as oxyhydroxides. No acute toxicity was observed during resuspension; however, mortality of D. magna and H. azteca occurred during the postexposure period. Daphnia magna also exhibited chronic toxicity, with decreased neonate production after exposure. This sublethal effect could lead to decreased zooplankton populations over a longer period in the reservoir. Environ Toxicol Chem 2019;38:1476-1485. © 2019 SETAC.