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The study was carried out to assess heavy metal concentrations in water, gills and liver of Tilapia zilli sampled from Wasai Reservoir from January 2019 to June 2020, with the aim of predicting health risk to the consumers. Sampling stations were selected based on variation of human activities around the water body. Levels of metals were determined using Microwave Plasma Emission Spectroscopy (MP-AES). The results indicated that metal concentrations in water followed the following order: Zinc (2.55 mg/L) > Chromium (0.067 mg/L) > Lead (0.058 mg/L) > Cadmium (0.031 mg/L), with Arsenic undetected. The Bioaccumulation Factor (BAF) showed that heavy metal accumulation in fish tissues was highest for Zn, followed by Pb, Cr, Cu, Cd, and As. Significant differences (P<0.05) were observed in the heavy metal concentrations across sampling stations, months, and seasons, except for Cr and Cd, which did not show significant variations (P>0.05). Fish tissue analysis revealed significant increases (P<0.05) in the gills (Cu > Pb > Zn > Cr > As > Cd) and liver (Cu > Pb > Zn > Cd > Cr > As). Pearson's correlation coefficient indicated strong positive correlations for Zn, Cr, Cd, and Pb (P<0.01), while negative correlations were observed for Cd and Cu (P<0.01). The study concluded that heavy metal pollution significantly affected fish physiology and water quality in the reservoir, primarily due to anthropogenic activities. It recommends the implementation of proper reservoir management systems to conserve this vital ecosystem and prevent its long-term deterioration. [ABSTRACT FROM AUTHOR]

Abstract Marine organisms are simultaneously exposed to numerous pollutants, among which metals probably represent the most abundant in marine environments. In order to evaluate the effects of metal exposure at molecular level in reproductive tissues, we profiled the sea urchin transcriptional response after non-lethal exposures using pathway-focused mRNA expression analyses. Herein, we show that exposures to relatively high concentrations of both essential and toxic metals hugely affected the gonadic expression of several genes involved in stress-response, detoxification, transcriptional and post-transcriptional regulation, without significant changes in gonadosomatic indices. Even though treatments did not result in reproductive tissues visible alterations, metal exposures negatively affected the main mechanisms of stress-response, detoxification and survival of adult P. lividus. Additionally, transcriptional changes observed in P. lividus gonads may cause altered gametogenesis and maintenance of heritable aberrant epigenetic effects. This study leads to the conclusion that exposures to metals, as usually occurs in polluted coastal areas, may affect sea urchin gametogenesis, thus supporting the hypothesis that parental exposure to environmental stressors affects the phenotype of the offspring. Highlights • Non-lethal metal exposures do not modify sea urchin gonadosomatic indices. • Metal exposures affect mRNA expression profile in sea urchin reproductive tissues. • Coexposures attenuates transcriptional response. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if temporal variations in tissue metal concentrations are related to biomarkers of retinoid metabolism and oxidative stress responses in juvenile yellow perch ( Perca flavescens ). To this end, kidney metal (Cd, Cu and Zn) concentrations were measured in fish sampled in spring and fall 2012 in four lakes representing a wide range of water and sediment metal contamination in the Rouyn-Noranda (Quebec) region. Lakes Opasatica and Hélène were considered as reference lakes while lakes Dufault and Marlon were metal-contaminated. Kidney concentrations of Cd, Cu and Zn varied widely between spring and fall in fish from both clean and metal-contaminated lakes. An inter-lake difference in renal metal concentrations was only observed for Cd, with fish from Lake Marlon consistently displaying higher concentrations. In the spring, the concentrations of liver dehydroretinol, dehydroretinyl palmitate and total vitamin A esters were higher in fish sampled in the most contaminated lake. Strong temporal variations in the concentrations of these metabolites, as well as in the percentage of liver free dehydroretinol and the epidermal retinol dehydrogenase 2 transcription levels, were observed in fish living in the most metal-impacted lake, with generally higher values in the spring. In contrast to liver, in muscle, no clear seasonal variations in the concentrations of dehydroretinol, dehydroretinyl stearate or in the percentage of free dehydroretinol were observed in fish captured in the most contaminated lake. Temporal variations of traditional biomarkers of oxidative stress response were also observed in the most metal-impacted lake. For example, the transcription level of the gene encoding Cu/Zn superoxide dismutase-1 in liver and muscle catalase activity of perch sampled in the most contaminated lake were higher in spring than in fall. Positive relationships were found between kidney Cd concentrations and the transcription level of the gene encoding glucose 6-phosphate dehydrogenase, and all forms of retinoid concentrations in liver in spring, except with the percentage of free dehydroretinol where the correlation was negative. Our results translate to a state of stress caused by Cd and illustrate that temporal variations in tissue metal concentrations affect retinoid metabolism and antioxidant capacities in juvenile wild yellow perch. Overall this study contributes to highlight the importance of considering temporal variations when investigating the consequences of metal contamination on the physiology of wild fish. [ABSTRACT FROM AUTHOR]

Biotic Ligand Models (BLMs) for individual metals improve our ability to regulate metals in the aquatic environment by considering the effects of water quality parameters (ionic composition, pH, DOC) on metal bioavailability. However, in natural aquatic systems, organisms are often simultaneously exposed to multiple metals and these interactions are not currently considered in BLMs or most environmental regulations. Recently, several different mixture BLMs (mBLMs) have been developed to begin assessing this issue. Some of these models assume competitive interactions between all metals, while others assume only metals with similar modes of action (e.g., Na + or Ca 2+ antagonists) will competitively interact. In this study, we used standard in vivo 3-h gill metal binding assays to characterize the uptake of Cd, Pb, and Zn individually and in binary mixtures with Ag, Cd, Cu, Pb, Ni, and Zn across a range of concentrations that encompassed the 96-h LC50 for each metal. Inhibition of Cd, Pb, and Zn uptake at the gill by introduction of a second metal was consistent with mode of action in some cases, but not others. Further, contrary to expectations, inhibition was always either non-competitive or could not be defined statistically. We also observed one example of stimulated metal uptake (Ni stimulated Zn uptake). Consistent with our previous experiments on Ag, Cu, and Ni, these studies suggest that current mBLM frameworks will need revision to better reflect the mechanisms underlying metal mixture interactions. [ABSTRACT FROM AUTHOR]

The nickel impacts on antioxidant enzymes’ activities such as superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and hepatic enzymes’ activity were studied in freshwatercarassius auratus. Probite analysis was used to determine acute toxicity of nickel to the goldfish. Fish were subjected to selected concentrations of nickel (control 0, 10, 20, 50, 100, 150, 200, 250 and 300 ppm) and the mortality data were determined after 24, 48, 72 and 96 h. The 96 h LC50 value of nickel to the fish was found to be 95.39 ± 0.73 ppm. SOD, GPx and CAT activities were monitored in the liver. These were determined in goldfish exposed to sub-lethal concentrations (40% and 80% LC50 at 7 days of exposure). There was a marked increase in SOD within both exposure groups and GPx was observed in this tissue having exposure to nickel (P < .05) but CAT was decreased in both the groups (P < .05). AST, ALP, ALT enzymes’ activity in both groups (40% and 80% LC50) was increased significantly when compared to that of the control group (P < .05). This result implied that increasing the dosage of nickel exposure induced antioxidant and hepatic enzymes’ activity in the goldfish. [ABSTRACT FROM PUBLISHER]

The Pacific oyster ( Crassostrea gigas ) can accumulate high levels of zinc (Zn) without obvious toxicity, but the related molecular mechanisms are largely unknown. In the present study, C. gigas were exposed to excess Zn for 9 days and the differentially expressed proteins (DEPs) were examined using the isobaric tags for relative and absolute quantitation (iTRAQ) method. In total, 2667 proteins containing at least two peptides and detected in both replicates were used for proteomic analysis. Among these DEPs, 332 were up-regulated and 282 were down-regulated. KEGG enrichment analysis of DEPs revealed that Zn exposure mainly distrubed ‘tricarboxylic acid (TCA) cycle’, ‘electron transport chain (ETC)’ and ‘glutathione (GSH) metabolism’ processes in oysters. Further key protein expressions enriched in these metabolism pathways were analyzed. In TCA cycle, Zn inhibited the Fe-containing protein expressions, which may lead to the accumulation of succinate and induce anaerobiosis. In ETC metabolism process, Zn inhibited ETC complex protein expressions, including complex I–IV, which may affect the electron transport process. Furthermore, Zn induced phytochelatin (PC) and glutathione peroxidase (GPX) expression in GSH catabolism. The proteins play important roles in Zn detoxification and ROS elimination process. The transcriptional expressions of genes encoding these proteins were observed using real-time PCR analysis, and there was good consistency between these two datasets. Overall, we provide direct evidence for Zn toxicity and detoxification mechanisms at protein level. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a naturally occurring trace metal that is widely considered to be highly toxic to aquatic organisms and a significant health hazard to humans (Amzal et al., 2009; Bernhoft 2013; Burger, 2008; Satarug et al., 2009). The zebrafish ( Danio rerio ) has been used as a model organism for toxicological studies with Cd (Banni et al., 2011; Blechinger et al., 2007; Chow et al., 2009; Chow et al., 2008; Favorito et al., 2011; Kusch et al., 2007; Matz et al., 2007; Wang and Gallagher, 2013). We asked what the lasting longitudinal effects would be from short early developmental Cd exposure (between 24 and 96 h post-fertilization) in a range that larvae might experience living atop typical Cd-containing surface sediments (0, 0.01, 0.1, 1.0 and 10 μM CdCl 2 : 1.124, 11.24, 112.4 and 1124 μg Cd/L). The goal of this exposure window was to specifically target secondary neurogenesis, monoaminergic differentiation and cardiovascular development, without affecting earlier patterning processes. Developmental abnormalities in body size and CNS morphology increased with concentration, but were statistically significant only at the highest concentration used (10 μM). Heart rate for Cd-treated larvae increased with concentration, and was significant even at the lowest concentration used (0.01 μM). Longitudinal survival was significantly lower for fish developmentally exposed to the highest concentration. Except for brain weight, overall morphology was not affected by developmental Cd exposure. However, developmental exposure to lower concentrations of Cd (0.01, 0.1, and 1.0 μM) progressively lowered cocaine-induced conditioned place preference (CPP), used to measure function of the reward pathways in the brain. Baseline heart rate was significantly lower in longitudinal fish developmentally exposed to 1.0 μM Cd. Cardiovascular response to isoproterenol, a potent ß-adrenergic agonist, in longitudinal adults was also significantly affected by developmental exposure to Cd at low doses (0.01, 0.1 and 1.0 μM). Surviving longitudinal adult fish exposed to the highest concentration of Cd showed normal CPP and cardiovascular physiology. The data imply that even lower exposure concentrations can potentially result in fitness-affecting parameters without affecting survival in a laboratory setting. [ABSTRACT FROM AUTHOR]

Environmental stressors such as high temperature and metal exposure may occur sequentially, simultaneously, previously in aquatic ecosystems. However, information about whether responses to high temperature depend on Cd exposure history is still unknown in fish. Zebrafish were exposed to 0 (group 1), 2.5 (group 2) and 5 μg/L (group 3) cadmium (Cd) for 10 weeks, and then each group was subjected to Cd-free water maintained at 26 °C and 32 °C for 7 days respectively. 26 indicators were used to compare differences between 26 °C and 32 °C in the liver of female zebrafish, including 5 biochemical indicators (activity of Cu/Zn-SOD, CAT and iNOS; LPO; MT protein), 8 molecular indicators of oxidative stress (mRNA levels of Nrf2, Cu/Zn-SOD, CAT, HSF1, HSF2, HSP70, MTF-1 and MT), 5 molecular indicators of inflammation (mRNA levels of IL-6, IL-1β, TNF-α, iNOS and NF-κB), 8 molecular indicators of metal transport (mRNA levels of, ZnT1, ZnT5, ZIP8, ZIP10, ATP7A, ATP7 B and CTR1). All biochemical indicators were unchanged in group 1 and changed in group 2 and 3. Contrarily, differences were observed in almost all of molecular indicators of inflammation and metal transport in group 1, about half in group 2, and few in group 3. We also found that all molecular indicators of oxidative stress in group 2 and fewer in group 1 and 3 were significantly affected by heat. Our data indicated that heat indicators of oxidative stress, inflammation and metal transport showed dependence of previous cadmium exposure in the liver of zebrafish, emphasizing metal pollution history should be carefully considered when evaluating heat stress in fish. [ABSTRACT FROM AUTHOR]

Microelement (As, Cd, Cr, Cu, Ni, Pb, and Zn) concentrations were determined in the muscle, skin, gill, and liver tissues of Carassius auratus gibelio collected from subsidence pools at three different coal mines in the Huainan coalfield in China. The concentrations of elements in the water were within the allowable levels for raising fish. However, the higher levels of these metals in sediment may pose potential harm on fish. It was found that the concentrations of Cr, Ni, and Zn in all fish tissues were higher, while As, Cd, and Pb levels were relatively low. Microelement accumulation appeared to be more widespread in subsidence pools than that in natural water. Elements accumulated in fish tissues differently: the highest metal concentrations were generally found in the liver tissues of the fish analyzed, whereas the lowest were recorded in the muscles. The mean element concentrations in muscle tissue from C. auratus gibelio collected from subsidence pools (As, 0.16 mg/kg; Cd, 0.06 mg/kg; Cr, 6.21 mg/kg; Cu, 1.61 mg/kg; Ni, 3.88 mg/kg; Pb, 1.76 mg/kg; and Zn, 12.80 mg/kg dry weight) were far below the allowable limit of the hygienic standard in fish proposed by the Ministry of Health in China, suggesting that the fish were safe for human consumption. A health risk assessment also suggested there was no risk from the analyzed elements for inhabitants near the Huainan coalfield that consume fish. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) has proved to be associated with numerous toxic effects in aquatic organisms via waterborne exposure. With a view to investigate Cd toxicity along a broad spectrum of exposures reaching from environmental to toxic, we employed adult zebrafish ( Danio rerio ) for an in vivo study. A number of 10 fish per tank were placed in 40 L tanks and were exposed for 30 days to 0.0, 5.0, 25, 50, 75, 100 and 1000 μg Cd per liter. There were 2 tanks for each Cd exposure (duplicate experiment). Mortality was recorded daily, dead fish were collected and tissue samples were obtained for histologic observation, whereas remaining tissues were stored for Cd burden determination. Surviving fish were collected at the end of the experiment. Median overall survival (OS) in days was found to be 9.0, 11.0, 8.0 and 7.0 for 25 μg/L, 50 μg/L, 75 μg/L and 100 μg/L respectively, with all of them showing mortality greater than 50%. Remarkably, fish exposed to the highest Cd concentration (1000 μg/L) survived the longest exhibiting a mean OS of 29.2 days. Cd determination in fish tissue was conducted with an in house ICP-MS method and levels ranged from 3.1 to 29.1 ng/mg. Log Cd tissue levels were significantly correlated with the log Cd exposure levels (r = 0.535, p < 0.001). The highest Cd burden was determined for fish exposed to 1000 μg Cd /L (mean = 12.2 ng/mg). Histopathology supported these results. Our findings disclose a deviation in toxic responses through the range of Cd concentrations, leading to nonlinear responses. These differentiated responses, could be linked to hormesis phenomena. [ABSTRACT FROM AUTHOR]

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In the present study, we have analyzed various biochemical and histopathological biomarkers in the Oreochromis mossambicus collected from 18 sites at Bhima River. The biochemical biomarkers viz. antioxidative enzymes in muscle viz. catalase, SOD, and GST, glycolytic enzymes in kidney viz. LDH and MDH, protein metabolic enzymes in liver, gill, brain, gonad and muscle viz. ALT and AST, neurotransmitter enzymes in muscle AChE, lipid peroxidation and histopathology in the liver and gill have been evaluated. The oxidative biomarkers, glycolytic enzymes, protein metabolic enzymes and lipid peroxidation were significantly (p < 0.01) higher and AChE in muscle were significantly inhibited (p < 0.01) in fishes from different sampling sites. The histopathology of the liver and gill were altered at different sampling sites. The liver histopathology showed hepatocytes vacuolization, haemorrhage, karyokinesis, necrosis, pyknotic nuclei, dilation of sinusoids and hepatocyte granular degeneration and in the gill histopathology showed distal lamellar gill tissue, diffuse epithelial hyperplasia and multifocal mucus cell hyperplasia, extensive edema of epithelial cells, blood congestion and edema in secondary lamellae. All the indicators are giving strong signals for contamination of the aquatic water bodies. The Bhima River is surrounded by several cities and agriculture land indicates that vigorous industrial activity coupled with intensive use of chemicals in agricultural practices may held. Therefore, based on our results, we could recommend that the investigated tissue and cell alterations may be successfully applied as reliable biomarkers for monitoring contaminated freshwater ecosystems. This study suggests that, the importance of antioxidative enzymes, cellular biomarkers, AChE, and histopathology used as biomarkers in aquatic ecosystem biomonitoring. [ABSTRACT FROM AUTHOR]

In the present study our major aim was to evaluate the up-to-date contamination status of the Topolnitsa reservoir. It is located in a region with intensive copper mining, which has been constantly contaminated with metals in the last few decades. Thus, we measured As, Cd, Cu, Ni, Pb, and Zn concentrations in surface water samples, as well as, in liver of common carp in three different seasons - spring, summer, and autumn 2013. Furthermore, we also studied the carp response to the water quality by observing its hepatic morphological structure and measuring some biochemical parameters (LDH, ALAT, and ASAT activity). In general, metal concentrations in the water varied, but As, Cu and Ni were present in all the three seasons. Cu concentrations were above the maximum permissible levels set by law. Metal concentrations in the liver were significantly higher than in the water (p<0.05). In addition, we observed severe hepatic histological alterations, which included degenerative changes - granular degeneration, vacuolar degeneration, hydropic degeneration, and fatty degeneration; necrotic changes (necrobiosis) - karyopyknosis, karyorrexis and karyolysis, and necrosis; and changes in the blood vessels - hyperemia in sinusoids and major blood vessels. We found that LDH activity was inhibited in the common carp liver from the Topolnitsa reservoir compared to the reference fish, but ALAT and ASAT activity was significantly increased compared to the reference. Based on our findings we consider that the metal-contaminated waters of the Topolnitsa reservoir lead to negative changes at tissue and cellular level in the fish organism, which include altered structure and impaired functions of the liver. [ABSTRACT FROM AUTHOR]

A new procedure for separation and preconcentration of trace amounts of Cu(II), Ni(II), Fe(III), Zn(II), Cr(III), Cd(II), and Pb(II) in fish samples was proposed. The procedure is based on the adsorption of these metal ions on the column of Amberlite XAD-7 as congo red complexes prior to their determination by flame atomic absorption spectrometry (FAAS). Several factors that can affect the sorption and elution efficiency of the metal ions were investigated and optimized. The sorption was quantitative in the pH range of 6.0–9.0 for Cu(II) and Ni(II), 5.5–8.0 for Fe(III), 6.0–8.5 for Zn(II) and Cd(II), and 7.0–8.5 for Cr(III) and Pb(II). The optimum pH for simultaneous retention was 7.5. The sorption capacity of the resin was found to be 0.89, 0.72, 0.82, 0.61, 0.53, 0.84, and 0.78 mg/g for Cu(II), Ni(II), Fe(III), Zn(II), Cr(III), Cd(II), and Pb(II), respectively. The precision of the method was evaluated as the relative standard deviation obtained by analyzing a series of six replicates and below 6% for all seven elements. The validation of the method was performed by the analysis of certified reference materials. The proposed method was successfully applied to separation/preconcentration and determination of these metals in fish samples. [ABSTRACT FROM AUTHOR]

Because of different reported effects of parasitism on the accumulation of metals in fish, it is important to consider parasites while interpreting bioaccumulation data from biomonitoring programmes. Accordingly, the first step is to take parasitism into consideration when simulating metal bioaccumulation in the fish host under laboratory conditions. In the present study, the accumulation of metals in fish-parasite systems was simulated by a one-compartment toxicokinetic model and compared to uninfected conspecifics. As such, metal accumulation in fish was assumed to result from a balance of different uptake and loss processes depending on the infection status. The uptake by parasites was considered an efflux from the fish host, similar to elimination. Physiological rate constants for the uninfected fish were parameterised based on the covalent index and the species weight while the parameterisation for the infected fish was carried out based on the reported effects of parasites on the uptake kinetics of the fish host. The model was then validated for the system of the chub Squalius cephalus and the acanthocephalan Pomphorhynchus tereticollis following 36-day exposure to waterborne Pb. The dissolved concentration of Pb in the exposure tank water fluctuated during the exposure, ranging from 40 to 120 μg/L. Generally, the present study shows that the one-compartment model can be an effective method for simulating the accumulation of metals in fish, taking into account effects of parasitism. In particular, the predicted concentrations of Cu, Fe, Zn, and Pb in the uninfected chub as well as in the infected chub and the acanthocephalans were within one order of magnitude of the measurements. The variation in the absorption efficiency and the elimination rate constant of the uninfected chub resulted in variations of about one order of magnitude in the predicted concentrations of Pb. Inclusion of further assumptions for simulating metal accumulation in the infected chub led to variations of around two orders of magnitude in the predictions. Therefore, further research is required to reduce uncertainty while characterising and parameterising the model for infected fish. [ABSTRACT FROM AUTHOR]

Food web structure is a fundamental feature of ecosystems. Stable isotopes ( δ15N and δ13C) are used to estimate the relative contribution of food sources to consumer's diets (e.g. mixing models)., In complex food webs, the use of δ15N and δ13C measurements cannot always solve trophic interactions and distinguish among aquatic organisms with different feeding habits if little intra- and interspecific isotopic differentiation occurs., We have developed a method to characterize trophic relationships using Bayesian stable isotope mixing models in combination with trace metal data as prior information. Trace metal information is useful because of the high correspondence between trace metal profiles in consumers and their food sources, as we show here in an example of concentrations of fish and their expected dietary items., Trace metal concentration allows a more accurate estimation of relative contributions of food sources to consumer species compared to estimates based only on stable isotope values. We show the improvement of the procedure using four freshwater fish species with well-known feeding habits. The method provides a better estimation of the inter- and intraspecific dietary variability and correspondence with the feeding habits of these species., The approach described shows a considerable potential as a tool to assess trophic links in situations in which stable isotope methods are not conclusive. The method can be applied using other compounds that bioaccumulate in consumers (e.g. persistent organic pollutants). [ABSTRACT FROM AUTHOR]

Liver and blood δ-aminolevulinic acid dehydratase (ALA-D) inhibition by exposure to sub-lethal lead concentrations over time in Nile tilapia ( Oreochromis niloticus ) were investigated. All three lead concentrations (1 mg kg −1 , 10 mg kg −1 and 100 mg kg −1 ) significantly inhibited ALA-D activity in blood (319±29.2; 180±14.6 and 172±19 µmols −1 h −1 L −1 respectively) and liver (302±5.84; 201±41.4 and 93±22.1 µmols −1 h −1 L −1 ) 24 h after injection relative to controls (blood: 597±37.0 µmols −1 h −1 L −1 ; liver: 376±23.1 µmols −1 h −1 L −1 ). Blood ALA-D was greatly inhibited in all but the highest lead dose. Fish were then exposed to 1 mg kg −1 lead for 9 days, and presented short-term hyperglycemia, decreased hemoglobin and hematocrit values and time-dependent blood ALA-D activity inhibition, corroborating blood ALA-D activity as being more suitable for investigating lead effects, showing dose and time-dependent ALA-D inhibition after lead exposure. The results of the present study also demonstrated that fish size affects blood ALA-D activity, as fish from the 24-h assay, which were slightly smaller (approximately 200 g), showed higher ALA-D inhibition in response to lead exposure when compared to the fish from the 9-day assay (approximately 500 g). Thus, fish size should always be taken into account both in the field and in laboratory settings, and efforts should be made to obtain uniform fish size samples for biomarker studies. [ABSTRACT FROM AUTHOR]

The combined use of guided quantitative expert analysis and of multivariate exploratory data analysis is reported as a robust, sensitive and sufficiently specific approach to study European sea bass gill secondary lamellar pathology after exposure to incremental doses of cadmium and terbuthylazine up to 48 h. The following elementary pathological findings were considered: “epithelial lifting”, “epithelial shrinkage”, “epithelial swelling”, “pillar cells coarctation”, “pillar cells detachment”, “channels fusion”, “chloride cells swelling”, and “chloride cells invasion”. The relative spatial extension was determined according to exposure class and data were analyzed by means of canonical correspondence analysis (CCA), linear discriminant analysis (LDA) and canonical variates analysis (CVA). Histologically and ultrastructurally, cellular shrinkage/coarctation prevailed in cadmium exposed lamellae, whereas cellular swelling and epithelial lifting were predominant in terbuthylazine exposed lamellae compared to unexposed fish. Both CCA and CVA permit a good graphical data grouping according to exposure classes by means of the convex hull minimum polygons. This also reveals exposure dose and time gradients in CCA plot. Accordingly, epithelial swelling and epithelial shrinkage were comparatively associated to higher exposure time, whereas epithelial shrinkage and pillar cells coarctation were comparatively associated to higher exposure dose. LDA with only “epithelial shrinkage”, “epithelial swelling” and “pillar cells coarctation” in the model classified correctly 87.5% of the cross-validated cases. A possible pathogenetic relationship between the discriminant elementary lesions and the toxic mode of action at the cellular level of both cadmium and terbuthylazine is also discussed. [ABSTRACT FROM AUTHOR]

We study the transport properties of C 1− x Co x thin films (with x = 0.1, 0.15 and 0.2) grown on Si substrate by pulsed laser deposition technique. The results demonstrate some anomalous effects in the behavior of the measured resistance R ( T,x ). More specifically, for 0 < T < T ∗ range (with T ∗ ≃ 220 K ), the resistance is shown to be well fitted by a small polaron hopping scenario with R h ( T , x ) ∝ exp { [ T 0 ( x ) T ] 0.5 } and a characteristic temperature T 0 ( x ) ≃ T 0 ( 0 ) ( 1 − x ) (with T 0 (0) = 120 K ). While for higher temperatures T ∗ < T < T C ( x ), the resistance is found to be linearly dependent on spontaneous magnetization M ( T,x ), viz. R M ( T,x )∝ M ( T,x ), following the pattern dictated by electron scattering on cobalt atoms formed robust ferromagnetic structure with the Curie temperature T C ( x ) obeying a percolation like law T C ( x ) ≃ T C ( x m ) ( x / x m ) 0.15 with T C ( x m ) = 295 K and the maximum zero-temperature magnetization reaching M ( 0 , x m ) ≃ 0.5 μ B per Co atom for x m = 0.2. [ABSTRACT FROM AUTHOR]

Among the commercially available titanium alloys, the metastable β Ti-5553 alloy (Ti–5Al–5V–5Mo–3Cr–0.5Fe wt.%) is an object of great interest because it is employed in aerospace structural applications, primarily in the replacement of steel components. One of the primary advantages of this alloy is its high hardenability, which allows it to retain the β phase at room temperature, even at low cooling rates, thereby allowing the thermoprocessing of thick parts. The aim of this investigation was to evaluate the effect of the replacement of V with Nb on the hardenability of Ti-5553. Based on the molybdenum equivalent criterion, the Nb-modified Ti-5553 alloy was designed to present 12 wt.% of Nb instead of 5 wt.% of V. Samples of both alloys were prepared by melting them in an arc furnace under an inert atmosphere, heat-treated at high temperatures for 12 h and plastic deformed using swage forging. Finally, these samples were solution heat-treated at temperatures above the β-transus followed by cooling at different rates using water quenching, furnace cooling and a modified Jominy end quench test. Characterization was performed by measuring Vickers hardness, X-ray diffraction, and light optical, scanning electron and transmission electron microscopy. The results obtained indicate that metastable β phase can be retained when the cooling rate is higher than 21 °C/s for both alloys. At lower cooling rates, α phase precipitation was observed, but it appeared to be less evident in the Nb-modified Ti-5553, suggesting that the replacement of V with Nb increased the hardenability of the alloy. [ABSTRACT FROM AUTHOR]

In December 2008, an earthen retaining wall at the Tennessee Valley Authority (TVA) Kingston Fossil Fuel Plant failed and released 4.1 million m 3 of coal ash to rivers flowing into Watts Bar Reservoir in east Tennessee, United States (U.S.). As part of a comprehensive effort to evaluate the risks to aquatic resources from this spill – the largest in U.S. history – we compared bioaccumulation and maternal transfer of selenium (Se), arsenic (As), and mercury (Hg) in adult redear sunfish ( Lepomis macrolophus ), collected two years after the spill from both coal-ash exposed and non-exposed areas of the Emory and Clinch Rivers, with the success of embryo-larval development in their offspring. Whole body and ovary concentrations of Se in female sunfish at three study sites downstream of the spill were significantly elevated (site means = 4.9–5.3 and 6.7–9.0 mg/kg d.w. whole body and ovary concentrations, respectively) compared with concentrations in fish from reference sites upstream of the spill site (2.2–3.2 mg/kg d.w. for whole bodies and 3.6–4.8 mg/kg d.w. for ovaries). However, Se concentrations in coal ash-exposed areas remain below proposed U.S. Environmental Protection Agency (USEPA) criteria for the protection of aquatic life. Site-to-site variation in fish concentrations of As and Hg were not well-correlated with ash-exposure, reflecting the multiple sources of these metal(loid)s in the affected watersheds. In 7-day laboratory tests of embryos and larvae derived from in vitro crosses of eggs and sperm from these field-collected sunfish, fertilization success, hatching success, embryo-larval survival, and incidences of developmental abnormalities did not differ significantly between ash-exposed and non-exposed fish. Furthermore, these developmental endpoints were not correlated with whole body or ovary concentrations of Se, As, or Hg in the maternal fish, or with fish size, ovary weight, or gonadal-somatic indices. Results from this and related studies associated with the Kingston coal ash spill are consistent with proposed USEPA fish-based water quality criteria for Se, and to date continue to suggest that long-term exposures to sediment containing residual ash may not present a significant chronic risk to fish populations exposed to this major coal ash release. [ABSTRACT FROM AUTHOR]

A functioning olfactory response is essential for fish to be able to undertake essential behaviors. The majority of work investigating the effects of metals on the olfactory response of fish has focused on single-metal exposures. In this study we exposed rainbow trout to cadmium, copper, nickel, zinc, or a mixture of these four metals at or below the current Canadian Council of Ministers of the Environment guidelines for the protection of aquatic life. Measurement of olfactory acuity using an electro-olfactogram demonstrated that cadmium causes significant impairment of the entire olfactory system, while the other three metals or the mixture of all four metals did not. Binary mixtures with cadmium and each of the other metals demonstrated that nickel and zinc, but not copper, protect against cadmium-induced olfactory dysfunction. Testing was done to determine if the protection from cadmium-induced olfactory dysfunction could be explained by binding competition between cadmium and the other metals at the cell surface, or if the protection could be explained by an up-regulation of an intracellular detoxification pathway, namely metallothionein. This study is the first to measure the effects of binary and quaternary metal mixtures on the olfactory response of fish, something that will aid in future assessments of the effects of metals on the environment. [ABSTRACT FROM AUTHOR]

Maternal transfer of metals can be an important exposure route for animals. The maternal transfer of Cr and its effects on reproduction in fish are still largely unknown. In this study, Japanese medaka were exposed to a sublethal Cr(VI) concentration for 6 days (acute) and for 3 months (chronic). Chromium accumulation in the gonads, maternal transfer of Cr, and effects of Cr on the reproduction, histopathology and expressions of antioxidants in the gonads were evaluated. Both acute and chronic exposures resulted in significant Cr accumulation in gonads, eggs and larvae. In chronic Cr-exposed fish, approximately 61% of the Cr accumulated in the ovary was depurated by spawning during the first 3 days after exposure, suggesting that maternal transfer is a very important pathway for accumulation in offspring. The chronic exposure caused decreases in body weight, standard length, gonad weight, gonad-somatic index (GSI) and fecundity. The last of these was most severely affected: the total number of broods and eggs per female decreased by 57.1% and 75.9%, respectively. Moreover, egg weight and fertilization rate were also reduced (by approximately 20%) following chronic Cr(VI) exposure. Histopathological analyses showed that the Cr exposure resulted in the onset of follicular atresia and a reduction in the number of mature oocytes, along with a reduction in abundance of mature spermatozoa in testes. The GSH/GSSG ratio was greatly elevated after chronic Cr(VI) exposure, implying that GSH played a role in scavenging the reactive oxygen species generated by the reduction of Cr(VI) inside cells. This study provides evidence for the maternal transfer of Cr, highlights the importance of spawning in Cr depuration from the ovary, and demonstrates that chronic Cr(VI) exposure has serious impacts on reproduction in the Japanese medaka. Our results suggest that the issue of chronic Cr pollution deserves more attention than it has received to date. [ABSTRACT FROM AUTHOR]

Sediment is recognized as a major environmental sink for contaminants, including engineered nanoparticles (NPs). Consequently, sediment-living organisms are likely to be exposed to NPs. There is evidence that both accumulation and toxicity of metal NPs to sediment-dwellers increase with decreasing particle size, although NP size does not always predict effects. In contrast, not much is known about the influence of particle shape on bioaccumulation and toxicity. Here, we examined the influence of copper oxide (CuO) NP shape (rods, spheres, and platelets) on their bioaccumulation kinetics and toxicity to the sediment-dwelling gastropod, Potamopyrgus antipodarum . The influence of Cu added as CuCl 2 (i.e., aqueous Cu treatment) was also examined. Exposure to sediment mixed with aqueous Cu or with different-shaped CuO NPs at an average measured exposure concentration of 207 μg Cu per g dry weight sediment for 14 days did not significantly affect snail mortality. However, growth decreased for snails exposed to sediment amended with CuO NP spheres and platelets. P. antipodarum accumulated Cu from all Cu forms/shapes in significant amounts compared to control snails. In addition, once accumulated, Cu was efficiently retained (i.e., elimination rate constants were generally not significantly different from zero). Consequently, snails are likely to concentrate Cu over time, from both aqueous and NP sources, resulting in a high potential for toxicity. [ABSTRACT FROM AUTHOR]

Branchial Na ＋ -K ＋ -ATPase (NKA) activity has been suggested as a promising biomarker for assessing metal stress in aquatic organisms. However, studies that systematically show the effectiveness of using NKA activity to detect metal exposure and toxicity at the individual level are limited. In this study, we aimed to determine whether branchial NKA activity mechanistically responds to the accumulation of waterborne copper (Cu) and accounts for observed toxicity over time under environmentally-relevant and aquafarming Cu exposure levels (0.2, 1 and 2 mg L −1 ). Temporal trends in Cu accumulation and the corresponding responses of branchial NKA activity resulting from Cu exposure were investigated in laboratory experiments conducted on juvenile tilapia ( Oreochromis mossambicus ), a freshwater teleost that shows potential as a bioindicator of real-time and historical metal pollution. We used the process-based damage assessment model (DAM) to inspect the time course of Cu toxicity by integrating the compensation process between Cu-induced inhibition and repair of branchial NKA activity. NKA activity acted as a sensitive biomarker for Cu exposure and accumulation in tilapia, which showed induced impairment of osmoregulation and lethality when they were exposed to environmentally relevant levels (0.2 mg L −1 ), but not to higher exposure levels (1 and 2 mg L −1 ) in aquaculture farms or contaminated aquatic ecosystems. This study highlights the benefits and limitations of using branchial NKA activity as a sensitive biomarker to assess the health status of a fish population and its ecosystem. [ABSTRACT FROM AUTHOR]

Among xenobiotics, metals gained attention because of their toxicity and harmful effects on aquatic ecosystems, fish and the human health. Present experiment was conducted to determine the genotoxic effects of individual metals viz. arsenic (As), copper (Cu), and zinc (Zn) in peripheral blood erythrocytes of four freshwater fish species viz. Labeo rohita (rohu), Cirrhina mrigala (mori), Catla catla (thaila) and Ctenopharyngodon idella (grass carp) by using Comet assay. For this purpose fish were exposed to four different sub-lethal concentrations (17, 25, 33 and 50% of LC50) of As, Cu, and Zn for a period of 30-day. All the four fish species showed significantly different extant of DNA damage in-terms of percent damaged cells, genetic damage index (GDI) and cumulative tail length of comets due to metals exposure. Among four fish species, Cirrhina mrigala showed significantly (P<0.05) higher percentage of damaged cells, GDI and cumulative tail length of comets with the mean values of 52±6%, 1.6±0.3 and 152±35 µm, respectively. However, Catla catla showed significantly lower percentage of damaged cells and GDI with the mean values of 29±4% and 1.1±0.1, respectively. This study indicated that individual metals and metals mixture, existing in aquatic habitats of Pakistan can induce DNA damage in indigenous fish fauna. [ABSTRACT FROM AUTHOR]

During this research endeavor, the chronic effects of dual exposure (waterborne+dietary) of cadmium (Cd), zinc (Zn) and copper (Cu) on the growth performance and tissue-specific bioaccumulation of metals in three age groups (60-, 90- and 120-day) of Cirrhina mrigala were determined. The exposure of all metals caused significant effects on the weight and total length gains in all three age groups of fish. Fish growth was significantly affected due to Cu, followed by Cd and Zn exposures. However, growth of treated fish was significantly lesser than control (un-stressed). Fish condition factor did not change significantly due to treatments. Zn exposure induced significantly better feed intake in fish than Cd and Cu treatments. Feed conversion efficiency (FCE) of fish varied significantly due to treatments that changed with age also. Exposure of fish to metals caused significant alterations in fish feeding patterns that caused profound effects on fish growth and FCE. Therefore, fish growth has been found reliable end point in chronic dual exposure of Cd, Zn and Cu to predict various processes associated with fish bioenergetics. The chronic dual exposure of metals resulted into significantly inconstant buildup of Cd, Zn and Cu in fish body organs also. In general, all metals exhibited their bioaccumulations in fish that followed the order: liver > kidney > gills > muscles > fins > skins > bones. The 60-dayfish displayed significantly higher propensity to accrue all metals while Zn accumulation was significantly higher than both Cd and Cu in the fish body. [ABSTRACT FROM AUTHOR]

The marine environment of the Red Sea coast of Yemen Republic is subjected to increasing anthropogenic activities. The present field study assesses the impacts of metal pollutants on two common marine fish species; Pomadasys hasta and Lutjanus russellii collected from a reference site in comparison to two polluted sites along the Red Sea coast of Hodeida, Yemen Republic. Concentrations of heavy metals (Fe, Cu, Zn, Cd and Pb) in fish vital organs, metal pollution index (MPI), indicative biochemical parameters of liver functions (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) and kidney functions (urea and creatinine) as well as histopathological changes in gills, liver and kidney of both fish species are integrated as biomarkers of metal pollution. These biomarkers showed species-specific and/or site-specific response. The hazard index (HI) was used as an indicator of human health risks associated with fish consumption. The detected low HI values in most cases doesn’t neglect the fact that the cumulative risk effects for metals together give an alarming sign and that the health of fish consumers is endangered around polluted sites. The levels of ALT, AST and urea in plasma of both fish species collected from the polluted sites showed significant increase in comparison to those of reference site. Histopathological alterations and evident damage were observed in tissues of fish collected from the polluted sites. The investigated set of biomarkers proved to be efficient and reliable in biomonitoring the pollution status along different pollution gradients. [ABSTRACT FROM AUTHOR]

Superoxide dismutases (SODs) are ubiquitous family of metalloenzymes involved in protecting organisms from excess reactive oxygen species damage. In this paper, a novel intracellular Cu/ZnSOD from Sepiella maindroni (designated as SmSOD) was identified and characterized. The full-length cDNA sequence of SmSOD (GenBank accession No. KF908850) was 709 bp containing an open reading frame (ORF) of 459 bp, encoding 153 amino acid residues peptide with predicted pI /MW (6.02/15.75 kDa), a 131 bp-5′- and 116 bp-3′- untranslated region (UTR). BLASTn analysis and phylogenetic relationship strongly suggested that the sequence shared high similarity with known Cu/Zn SODs. Several highly conserved motifs, including two typical Cu/Zn SOD family domains, two conserved Cu-/Zn-binding sites (H-47, H-49, H-64, H-120 for Cu binding, and H-64, H-72, H-81, D-84 for Zn binding) and intracellular disulfide bond (C-58 and C-146), were also identified in SmSOD. Time-dependent mRNA expression of SmSOD in hepatopancreas was recorded by quantitative real-time RT-PCR after Vibrio harveyi injection and Cd 2+ exposure. The results indicated that SmSOD was an acute-phase protein involved in the immune responses against pathogens and biological indicator for metal contaminants in aquatic environment. [ABSTRACT FROM AUTHOR]

Metal levels in fish have been extensively studied, but little data currently exists for the Middle East. We examined the levels of metals and metalloids (aluminum, arsenic, copper, manganese, selenium, zinc, and mercury) in the flesh of 13 fish species collected from three fishing sites and a local fish market in Jeddah, Saudi Arabia. We tested the following null hypotheses: (1) there are no interspecific differences in metal levels, (2) there are no differences in metal levels in fishes between market and fishing sites, (3) there are no size-related differences in metal levels, and (4) there are no differences in selenium:mercury molar ratio among different fish species. There were significant interspecific differences in concentrations for all metals. There was an order of magnitude difference in the levels of aluminum, arsenic, mercury, manganese, and selenium, indicating wide variation in potential effects on the fish themselves and on their predators. Fishes from Area II, close to a large commercial port, had the highest levels of arsenic, mercury, and selenium, followed by market fishes. Mercury was positively correlated with body size in 6 of the 13 fish species examined. Mercury was correlated positively with arsenic and selenium, but negatively with aluminum, cobalt, copper, manganese, and zinc. Selenium:mercury molar ratios varied significantly among species, with Carangoides bajad, Cephalopholis argus, Variola louti, and Ephinephelus tauvina having ratios below 10:1. These findings can be used in risk assessments, design of mercury reduction plans, development of fish advisories to protect public health, and future management decision-making. [ABSTRACT FROM AUTHOR]

Concentration of trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb and As) in the muscle of six fish species was analyzed to determine the variation with fish size and fish species in an Iberian river with moderate metal pollution. Al, Fe and Zn were the most abundant metals across sites. Fish size and sampling site explained more variation than fish species, and a high intraspecific variability (among individuals) in metal loads was also observed. Considering the most spread species, concentrations were highest in bleak (Alburnus alburnus) and lowest in gudgeon (Gobio occitaniae) for all the elements. Metal loads were comparable with literature data from contaminated sites, often exceeding recommended European Environmental Quality Standards. The relationships between metal concentration and fish size varied markedly among sites, elements, and fish species. The slopes of these relationships were often significantly heterogeneous, a fact barely acknowledged in the literature, and were often negative, probably due to size-specific metabolic rates related to fish growth. [ABSTRACT FROM AUTHOR]

Highlights: [•] We use fish development, morphology, behaviour and otoliths to assess metal toxicity. [•] Fish embryos exposed to metal mixtures had lower survival and delayed development. [•] This resulted in poorer quality larvae that exhibited weaker phototactic behaviour. [•] Differences in metal exposure levels were permanently recorded in embryonic otoliths. [•] Otoliths could be a useful tool for linking past exposure to poor quality phenotypes. [Copyright &y& Elsevier]

Concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the muscle of eleven fish species (bighead carp, bream, catfish, carp, crucian, Culter alburnus, grass carp, mandarin fish, white semiknife carp, silver carp, and yellow catfish) from Poyang Lake were analysed using inductive coupling plasma mass spectrometry. Metal levels in other organs (e.g., bladder, gill, kidney, liver, and spleen) of bighead carp, carp, grass carp, and silver carp were also determined. The results showed that metal concentrations in the muscle of all fish species were significantly lower than the proposed limits. Heavy metal concentrations were found to be substantially higher in benthic fish than in pelagic fish. Higher Hg contents were observed in predatory fish. In addition, various metals showed different affinity to fish organs. Hg was the most abundant in muscle, while Ni and Pb concentrations were highest in gills, Cd and Zn concentrations were highest in kidneys, and Cu was most commonly found in livers. Estimations of health risks revealed no evidence of potential threats to consumers. [Copyright &y& Elsevier]

Using rare minnow (Gobiocypris rarus) embryos as experimental model, the developmental toxicity of Cu, Zn and Cd were investigated following exposure to 0.001–1.000mg/L for 72h, and the toxicity effects were evaluated by larval malformation rate, heart rate, pericardial area, spontaneous movements, tail length, enzyme activities and biomarker genes. Our results revealed that increased malformation rate provide a gradual dose–response relationship, and the most pronounced morphological alteration was heart and body malformations. Values of 72h EC50 with their 95 percent confidence intervals on G. rarus embryos were 0.103 (0.072–0.149)mg/L for Cu, 0.531 (0.330–1.060)mg/L for Zn, 0.219 (0.147–0.351)mg/L for Cd. Enzyme activities can be regard as a type of low-dose stimulation and high-dose inhibition. Stress and metabolism-related genes (hsp70, cyp1a and mt) were significantly up-regulated, development-related genes (wnt8a, vezf1 and mstn) were significantly down-regulated after the treatment by Cu, Zn and Cd. Overall, the present study points out Cu, Zn and Cd are highly toxic to G. rarus embryos. The information presented in this study will be helpful in fully understanding the toxicity induced by Cu, Zn and Cd in fish embryos. [Copyright &y& Elsevier]

Background: A convergence of technological breakthroughs in the past decade has facilitated the development of rapid screening tools for biomarkers of toxicant exposure and effect. Platforms using the whole adult organism to evaluate the genome-wide response to toxicants are especially attractive. Recent work demonstrates the feasibility of this approach in vertebrates using the experimentally robust zebrafish model. In the present study, we evaluated gene expression changes in whole adult male zebrafish following an acute 24 hr high dose exposure to three metals with known human health risks. Male adult zebrafish were exposed to nickel chloride, cobalt chloride or sodium dichromate concentrations corresponding to their respective 96 hr LC20, LC40 and LC60. Histopathology was performed on a subset of metal-exposed zebrafish to phenotypically anchor transcriptional changes associated with each metal. Results: Comparative analysis identified subsets of differentially expressed transcripts both overlapping and unique to each metal. Application of gene ontology (GO) and transcription factor (TF) enrichment algorithms revealed a number of key biological processes perturbed by metal poisonings and the master transcriptional regulators mediating gene expression changes. Metal poisoning differentially activated biological processes associated with ribosome biogenesis, proteosomal degradation, and p53 signaling cascades, while repressing oxygen-generating pathways associated with amino acid and lipid metabolism. Despite appreciable effects on gene regulation, nickel poisoning did not induce any morphological alterations in male zebrafish organs and tissues. Histopathological effects of cobalt remained confined to the olfactory system, while chromium targeted the gills, pharynx, and intestinal mucosa. A number of enriched transcription factors mediated the observed gene response to metal poisoning, including known targets such as p53, HIF1α, and the myc oncogene, and novel regulatory factors such as XBP1, GATA6 and HNF3β. Conclusions: This work uses an experimentally innovative approach to capture global responses to metal poisoning and provides mechanistic insights into metal toxicity. [ABSTRACT FROM AUTHOR]

Abstract: We report the concentrations of 28 PAHs, 15 oxygenated PAHs (OPAHs) and 11 trace metals/metalloids (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn) in muscle and gut+gill tissues of demersal fishes (Drapane africana, Cynoglossus senegalensis and Pomadasys peroteti) from three locations along the coast of the Gulf of Guinea (Ghana). The concentrations of ∑28PAHs in muscle tissues averaged 192ngg−1 dw (range: 71–481ngg−1 dw) and were not statistically different between locations. The concentrations of ∑28 PAHs were higher in guts+gills than in muscles. The PAH composition pattern was dominated by low molecular weight compounds (naphthalene, alkyl-naphthalenes and phenanthrene). All fish tissues had benzo[a]pyrene concentrations lower than the EU limit for food safety. Excess cancer risk from consumption of some fish was higher than the guideline value of 1×10−6. The concentrations of ∑15 OPAHs in fish muscles averaged 422ngg−1 dw (range: 28–1715ngg−1dw). The ∑15 OPAHs/∑16 US-EPA PAHs concentration ratio was >1 in 68% of the fish muscles and 100% of guts+gills. The log-transformed concentrations of PAHs and OPAHs in muscles, guts+gills were significantly (p <0.05) correlated with their octanol–water partitioning coefficients, strongly suggesting that equilibrium partitioning from water/sediment into fish tissue was the main mechanism of bioaccumulation. The trace metal concentrations in the fish tissues were in the medium range when compared to fish from other parts of the world. The concentrations of some trace metals (Cd, Cu, Fe, Mn, Zn) were higher in guts+gills than in muscle tissues. The target hazard quotients for metals were<1 and did not indicate a danger to the local population. We conclude that the health risk arising from the consumption of the studied fish (due to their PAHs and trace metals content) is minimal. [Copyright &y& Elsevier]

Highlights: [•] Waterborne Zn exposure differentially affects carntine composition in fish. [•] Differential effect on CPT I kinetics is found in fish exposed to Zn. [•] Zn differentially affects the mRNA levels of four CPT I isoforms in fish. [•] Zn changes CPT I kinetics via altering its expression and carnitine status. [Copyright &y& Elsevier]

Quantum dots (QDs) have strong adsorption capacity; therefore, their potential toxicity of the facilitated transport of other trace toxic pollutants when they co-exist to aquatic organisms has become a hot research topic. The lab study was performed to determine the developmental toxicities to the zebrafish after exposed to the combined pollution of Cadmium-telluride (CdTe) QDs and copper ion (Cu2+) compared to the single exposure. Our findings for the first time revealed that: 1) CdTe QDs facilitated the accumulation of Cu2+ in zebrafish, 2) the higher mortality, lower hatch rate, and more malformations can be clearly observed, 3) the diverse vascular hyperplasia, turbulence, and bifurcation of the exposed FLI-1 transgenic zebrafish larvae appeared together, 4) the synergistic effects played more important role during joint exposure. These observations provide a basic understanding of CdTe QDs and Cu2+ joint toxicity to aquatic organisms. [Copyright &y& Elsevier]

This study presents concentrations of iron, manganese, zinc, and copper in selected tissues of two fish species: pike ( Esox lucius L.) and bream ( Abramis brama L.) living in lakes Ińsko and Wisola, Northwestern Poland. The lakes differ in their trophic status. The effect of gender and environmental conditions on metals accumulation was also investigated. Metal analyses were performed using inductively coupled plasma atomic emission spectroscopy. Considering all studied fish species and tissues, the average metal concentrations (micrograms per gram wet weight) in both lakes occurred in the following ranges: Fe 0.8-240.6, Mn 0.2-8.4, Zn 3.0-185.9, and Cu 0.14-7.76. The lowest levels of the studied metals were always detected in the muscles. The spleen, kidneys, and liver were found to accumulate the highest amounts of Fe. In the case of the other metals, the highest levels were found, as follows: Mn in skin, gills, and gonads, Zn in digestive tract and gills, Cu in liver. Heavy metal content in fish gonads was observed to be sex dependent. [ABSTRACT FROM AUTHOR]

Abstract: Metal (Cd, Pb, Cr, Ni, Mn, Cu, and Zn) concentrations in different fish species sampled from two distinct (phytoplankton- and macrophyte-dominated) lake zones of a large, shallow freshwater lake, Taihu Lake, were investigated. Concentrations of most metals in muscle of the small-sized fish (Protosalanx hyalocranius, Pseudorasbora parva, and Rhodeus ocellatus) were always significantly higher than those of the large-sized (Carassius auratus, Cyprinus carpio, and Aristichthys nobilis) and carnivorous fish (Pelteobagrus fulvidraco, Cultrichthys erythropterus, and Erythroculter ilishaeformis). Metal accumulation in the small-sized fish from the phytoplankton-dominated lake zone was always greater than those from the macrophyte-dominated lake zone in summer. However, no significant differences were observed between the two lake zones for most metals in the small-sized fish collected in winter. Metal accumulation in gills, liver, and intestine of the large-sized fish from the phytoplankton-dominated lake zone was generally greater than those from the macrophyte-dominated lake zone in summer. The presence of distinct ecological regions in the lake might affect the metal distribution in the small-sized or large-sized fish. For the carnivorous fish, however, metal concentrations in fish tissues from the two different lake zones were not significantly different, suggesting that metal accumulation in carnivorous fish might be less influenced by the ecological status of the lake. [Copyright &y& Elsevier]

In a recent study on indigenous yellow perch chronically exposed to metals, we reported a negative correlation between liver metal concentration and liver transcription levels of genes encoding for enzymes involved in the metabolism of retinoids. We therefore speculated that metals, and especially the non-essential metal Cd, could alter the metabolism of retinoids in wild fish. Thus the present field study investigates the impact of in situ metal exposure on retinoid storage. A total of 55 yellow perch (Perca flavescens) were sampled in six lakes representing a metal contamination gradient (8≤N≤10 per lake). Our results show that yellow perch from Cd-contaminated lakes had significantly higher concentrations of liver dehydroretinol and dehydroretinyl esters than did fish from reference lakes. However, the increase in retinyl ester stores with increasing Cd concentrations was quantitatively much more important than the increase in free dehydroretinol. As a result, a significant decrease in the percentage of hepatic free dehydroretinol with increasing renal Cd concentrations was observed. These results suggest that the enzymes and the binding proteins involved in vitamin A homeostasis are inhibited by the presence of Cd. Alternatively, the increase in tissue vitamin A (antioxidant) levels could serve to better counteract the oxidative stress engendered by Cd exposure. Overall our findings illustrate that vitamin A2 homeostasis can be altered as a consequence of chronic exposure to low Cd concentrations. Thus, in the context of environmental risk assessment, the percentage of liver free dehydroretinol can be considered as a biomarker of for in situ Cd exposure. [Copyright &y& Elsevier]

Abstract: More than half of pygmy sperm whales (Kogia breviceps) that strand exhibit signs of cardiomyopathy (CMP). Many factors may contribute to the development of idiopathic CMP in K. breviceps, including genetics, infectious agents, contaminants, biotoxins, and dietary intake (e.g. selenium, mercury, and pro-oxidants). This study assessed trace elements in K. breviceps at various stages of CMP progression using fresh frozen liver and heart samples collected from individuals that stranded along US Atlantic and Gulf coasts between 1993 and 2007. Standard addition calibration and collision cell inductively coupled plasma mass spectrometry (ICP-MS) were employed for total Se analysis and pyrolysis atomic absorption (AA) was utilized for total Hg analysis to examine if the Se/Hg detoxification pathway inhibits the bioavailability of Se. Double spike speciated isotope dilution gas chromatography ICP-MS was utilized to measure methyl Hg and inorganic Hg. Immunoblot detection and colorimetric assays were used to assess protein oxidation status. Data collected on trace elements, selenoproteins, and oxidative status were evaluated in the context of animal life history and other complementary histological information to gain insight into the biochemical pathways contributing to the development of CMP in K. breviceps. Cardiomyopathy was only observed in adult pygmy sperm whales, predominantly in male animals. Both Hg:Se molar ratios and overall protein oxidation were greater in males than females and increased with progression of CMP. [Copyright &y& Elsevier]

Anthropogenic activities can increase the salinity of freshwaters and this may cause stress for fish and affect metal bioavailability. Oxidative stress biomarkers are of great interest due to their responses to environmental stressors which provide valuable data for biological monitoring of aquatic pollution. Thus, the individual and combined effects of salinity and metals (Cr, Pb) were investigated in the liver of freshwater fish Oreochromis niloticus in the present study. Fish were exposed to salinity (2 and 8ppt) alone and salinity+metal (1μg/mL Pb and Cr) combination exposures for 0, 1, 7 and 14 days and subsequently antioxidant enzymes (superoxide dismutase, SOD; glutathione peroxidase, GPX; glutathione reductase, GR and glutathione S-transferase, GST) activities and glutathione (GSH) levels in the liver were measured. Data showed that all the parameters varied in relation to metal species, exposure durations and salinity levels. Profound alterations on the measured parameters were detected at the lower salinity compared to the higher one. Salinity increase effectively stimulated the antioxidant parameters. The effects of salinity and metals on the measured parameters increased as the exposure duration prolonged. SOD was the most affected antioxidant parameter from both salinity and metals. Because metal and salinity stresses affect fish antioxidant system, this work suggests that the chemistry of freshwaters should be taken into account in natural monitoring for metal contamination in the field. [Copyright &y& Elsevier]

Abstract: Metal gill binding and toxicity can be modeled using the concentration addition model, in which the toxic unit (TU) concept is used to determine if constituent metals are acting in a strictly additive, less than, or greater than additive fashion. To test this hypothesis, rainbow trout (Oncorhynchus mykiss) were exposed to a matrix of Pb plus Cd mixtures (nominal concentrations=0.75, 1.5, 2.25, 3.0μmolL−1), in the presence or absence of mainly terrigenous (allochthonous; 10mg CL−1) natural organic matter (NOM), and metal–gill binding, and toxicity was quantified. Based on its greater affinity for metal–gill binding sites, Cd–gill binding was expected to exceed Pb–gill binding during metal mixture exposure, but this only occurred at the lowest metal concentrations (0.75μmolL−1); at higher concentrations Pb–gill binding was greater than Cd–gill binding. These unexpected observations were because Pb and Cd likely bind to different populations of high affinity, low capacity binding sites on the gill, which was borne out in subsequent attempts to mathematically model metal–gill interactions during metal-mixture exposure. The presence of an additional low affinity, high capacity population of Pb–gill binding sites also contributed to higher Pb–gill accumulation. Metal–gill interactions were complicated by NOM, which exacerbated toxicity during Cd-only exposure despite lowering Cd–gill accumulation. NOM also promoted Cd–gill binding in the presence of low-moderate concentrations of Pb (0.75 and 1.50μmolL−1). We suggest that direct interactions of Cd–NOM complexes with the gill, and increases in Cd bioavailability due to Pb outcompeting Cd for NOM–metal binding sites due to its greater affinity for such ligands, accounted for greater Cd–gill binding and toxicity. We conclude that interactions of Pb and Cd with the gill cannot be predicted using the concentration addition model, and that NOM is not universally protective against metal–gill binding and toxicity when fish are exposed to metal mixtures. [Copyright &y& Elsevier]

Abstract: Since changes in metal distribution among tissues and subcellular fractions can provide insights in metal toxicity and tolerance, we investigated this partitioning of Cu in gill and liver tissue of rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio) and gibel carp (Carassius auratus gibelio). These fish species are known to differ in their sensitivity to Cu exposure with gibel carp being the most tolerant and rainbow trout the most sensitive. After an exposure to 50μg/l (0.79μM) Cu for 24h, 3 days, 1 week and 1 month, gills and liver of control and exposed fish were submitted to a differential centrifugation procedure. Interestingly, there was a difference in accumulated Cu in the three fish species, even in control fishes. Where the liver of rainbow trout showed extremely high Cu concentrations under control conditions, the amount of Cu accumulated in their gills was much less than in common and gibel carp. At the subcellular level, the gills of rainbow trout appeared to distribute the additional Cu exclusively in the biologically active metal pool (BAM; contains heat-denaturable fraction and organelle fraction). A similar response could be seen in gill tissue of common carp, although the percentage of Cu in the BAM of common carp was lower compared to rainbow trout. Gill tissue of gibel carp accumulated more Cu in the biologically inactive metal pool (BIM compared to BAM; contains heat-stable fraction and metal-rich granule fraction). The liver of rainbow trout seemed much more adequate in handling the excess Cu (compared to its gills), since the storage of Cu in the BIM increased. Furthermore, the high % of Cu in the metal-rich granule fraction and heat-stable fraction in the liver of common carp and especially gibel carp together with the better Cu handling in gill tissue, pointed out the ability of the carp species to minimize the disadvantages related to Cu stress. The differences in Cu distribution at the subcellular level of gills and liver of these fish species strongly reflects their capacity to handle Cu excess and is one of the greatest contributors to their difference in sensitivity to Cu. [Copyright &y& Elsevier]

Toxic effect of heavy metals due to nickel and chromium on bone tissues edible fish Cirrhinus mrigala wai studied using spectroscopic techniques. The study shows that there is significant change in the bone mineral contents and it is more pronounced in nickel than chromium. [ABSTRACT FROM AUTHOR]

To assess the interaction effect between cadmium (Cd) and 17 β-estradiol (E2), male Chinese loaches ( Misgurnus anguillicaudatus) were exposed to E2 (1 μg/L) and Cd (50 or 500 μg/L) alone and in combination using a semi-static waterborne exposure system. The effects of E2 on the accumulation and distribution of Cd, as well as the effects of Cd on vitellogenin (Vtg) synthesis induced by E2, were investigated. Cd mainly accumulated in the kidneys, liver, intestines, and gills, with little amounts in muscles, bones, and gonads. Co-exposure with E2 did not change the main targets for Cd. E2 could induce Vtg synthesis in male Chinese loaches, and co-exposure with 50 or 500 μg/L Cd could inhibit the Vtg induced by 1 μg/L E2. Compared with the results reported in the literature, it can be concluded that factors such as fish species, Cd dosage, and manner of exposure might make contributions to the interaction between Cd and E2. Our results also suggested that male Chinese loaches are susceptible to Cd, and can be recommended as a potential sentinel species to study the ecotoxicology of heavy metals. [ABSTRACT FROM AUTHOR]

The article offers information that geologic process influence water and sediment quality in aquatic ecosystems. A study was conducted to test the elevated concentrations of metals in water. It enabled to distinguish the aquatic ecosystem limited by metals derived from natural processes from those due to mining. Elevated concentrations of metals in water and sediment were not restricted to mined catchments. Results indicate that natural sources of metals as contribute to aquatic ecosystem.

The toxicity of heavy metals viz. aluminium (Al), arsenic (As), barium (Ba), chromium (Cr), nickel (Ni) and zinc (Zn) in fish at three main public fishing sites of the river Ravi viz. Shahdara bridge, Baloki headworks and Sidhnai barrage has been studied from June, 2009 to May, 2010. The concentrations of heavy metals in the body organs (gills, liver, kidney, intestine, reproductive organs, skin, muscle, fins, scales, bones, fats) of three fish species viz. Catla catla, Labeo rohita and Cirrhina mrigala were determined. The present results reveal that the toxicity of metals fluctuated significantly in fish at all the three sampling stations with season. The fish samples collected from all the three sampling stations had significantly higher aluminium and zinc. However, the fish at Sidhnai barrage showed significantly lower metallic toxicity, followed by that at Baloki headworks and Shahdara bridge. Significantly higher metals were observed in fish liver, followed by that of kidney, gills, intestine, reproductive organs, skin, scales, fins, bones, muscle and fats. The accumulation of metals in carnivorous fish body organs showed significantly direct dependence on the metallic toxicity of herbivorous cyprinids. Fish liver and kidney showed significantly higher abilities for the accumulation of all metals while accumulations were lowest in fish muscle and fats. The health status of river Ravi at three main public fishing sites viz. Shahdara bridge, Baloki headworks and Sidhnai barrage, with respect to eco-toxicity of Al, As, Ba, Cr, Ni and Zn was above the recommended permissible standards [ABSTRACT FROM AUTHOR]

Abstract: The influence of exposure time on gill Na+/K+ ATPase activity and metabolic rate in populations of fathead minnows (Pimephales promelas) and golden shiners (Notemigonus crysoleucas) hatcheries in Ohio (OH) and Pennsylvania (PA) when exposed to sublethal concentrations of copper (Cu) was examined. The pattern of change in gill Na+/K+ ATPase activity was similar in all species/populations and results support expectations based on the concept of acclimation. In all populations, Na+/K+ ATPase activity declined significantly compared to reference values within 24h, recovered by 48h, and then continued to increase before exceeding reference values by 192h. With the exception of PA fathead minnows, Na+/K+ ATPase activities returned to reference levels by 384h. Although metabolic rates of individual fish were not strongly correlated with Na+/K+ ATPase activities, the pattern of change in mean values of these physiological parameters was very similar. However, OH populations of both fathead minnows and golden shiners demonstrated much more dramatic changes in metabolic rate compared to PA fish. At 24h, metabolic rate of PA fathead minnows had decreased by 16% compared to the reference value whereas the OH population had decreased by 31%; metabolic rate of PA golden shiners declined by 23% compared to 59% in OH shiners at 24h. Similar differences were observed in the maximum metabolic rates achieved at 192h. While the increased sensitivity of OH fish to Cu is not readily explainable by genetic or environmental factors, results suggest the need for considering population level differences when evaluating the physiological effects of toxicants. [Copyright &y& Elsevier]