Bioaccumulation markers and biochemical responses in European sea bass (Dicentrarchus labrax) raised under different environmental conditions

Toxicity Assessment of Impacted Sediments from Southeast Coast of Tunisia Using a Biomarker Approach with the Polychaete Hediste diversicolor

Toxicity caused by exposure to pollutants from marine sediments is a consequence of the interaction between biota and xenobiotics most frequently released by anthropogenic activities. The present work intended to characterize the toxicity of natural sediments putatively impacted by distinct human activities, collected at several sites located in the south of the Gulf of Gabes, Zarzis area, Tunisia. The selected toxicity criteria were analysed following ecologically relevant test conditions. Organisms of the polychaete species Hediste diversicolor were chronically exposed (28 days) to the mentioned sediments. Toxicity endpoints were biomarkers involved in the toxic response to common anthropogenic chemicals, namely neurotoxic (acetylcholinesterase), anti-oxidant (catalase, glutathione peroxidase), metabolic (glutathione S-transferases) enzymatic activities, and oxidative damage (lipid peroxidation, TBARS assay). The chemical characterization of sediments showed that the samples collected from the site near an aquaculture facility were highly contaminated by heavy metals (Cd, Cu, Cr, Hg, Pb, and Zn) and polycyclic aromatic hydrocarbons (fluorene, phenanthrene, anthracene, fluoranthene and pyrene). H. diversicolor individuals exposed to the sediments from this specific site showed the highest values among all tested biomarkers, suggesting that these organisms were possibly under a pro-oxidative stress condition potentially promoted by anthropogenic pollution. Moreover, it was possible to conclude that individuals of the polychaete species H. diversicolor responded to the chronic exposure to potentially contaminated sediments from the southeast coast of Tunisia, eliciting adaptive responses of significant biological meaning.

Physiopathological responses of sole (Solea senegalensis) subjected to bacterial infection and handling stress after probiotic treatment with autochthonous bacteria

This study aimed to evaluate the protective effects of four autochthonous bacteria isolated from juvenile sole (Solea senegalensis) intestine as dietary probiotic supplement against bacterial pathogen infection and handling/transport stressors. Growth performance and immune responses were evaluated after 85 days of feeding trial. Sole (IBW = 16.07 ± 0.11 g) were fed six experimental diets, a control diet (CTRL, without the dietary probiotic supplementation), and five diets supplemented with probiotic bacteria: PB1 (Shewanella hafniensis), PB2 (Enterococcus raffinosus), PB3 (Shewanella hafniensis + Arthrobacter soli), PB4 (Pseudomonas protegens + Arthrobacter soli) and PB5 (Shewanella hafniensis + Arthrobacter soli + Enterococcus raffinosus). All bacteria were selected based on their in vitro antimicrobial activity. After the growth trial, fish were submitted to a stress factor (transport) and then each dietary group was divided in two additional groups: non-infected (placebo) and infected with Photobacterium damselae subsp. piscicida. Immune and antioxidant responses were evaluated at day 10 post-infection. In infection trial A, fish were infected on the same day of transport, whereas in trial B fish were infected after a 7-day recovery from the transport stress. At the end of the feeding trial, fish fed with PB2 and PB4 showed lower final body weight when compared with the other dietary groups. Respiratory burst activity and nitric oxide production were not affected by probiotic supplementation. Fish fed with PB5 presented lower peroxidase activity compared to CTRL. Lysozyme and alternative complement pathway activity (ACH50) showed no significant differences between treatments. The innate immune responses were significantly affected after handling stress and bacterial infection. In trial A, the ACH50 levels of infected fish were significantly lower than the placebo groups. On the other hand, in trial B fish infected with Pdp demonstrated higher ACH50 levels when compared to placebos. Peroxidase levels were strongly modulated by bacterial infection and handling stress. In trials A and B, infection had a clear downgrade effect in peroxidase levels. Lipid peroxidation, catalase, glutathione S-transferase and glutathione reductase were altered by both bacterial infection and transport. Overall, dietary probiotic supplementation did not influence growth performance of sole. The immune and oxidative defenses of sole responded differently to infection depending on the probiotic and the synergy between pathogen infection and transport.

Impact of Metal Toxicity on Oxidative Balance and Mitochondrial Enzyme Function in Muscle of Tilapia

Present study investigates the effect of metal accumulation on antioxidant level and mitochondrial enzymes function in muscle of Oreochromis mossambicus. Metal accumulation in muscle upregulated stress marker malondialdehyde and the activity of different antioxidant enzymes with no significant alteration in glutathione system. Metal exposure to fish muscle decreased the activity of mitochondrial enzymes. AMP deaminase, aldolase, cytochrome C oxidase and lipoamide reductase showed positive correlation with acetylcholinesterase, glutathione reductase, reduced glutathione and glutathione peroxidase, but negative correlation with superoxide dismutase, catalase, glutathione S-transferase and thiobarbituric acid reactive substance. Analysis of these biomarkers clearly indicates the change in oxidative load in muscle tissues and provides insight to muscle response to the metal exposure. Therefore, the study outlines the potential use of biomarkers in context of muscle mitochondrial enzymes relating to oxidative processes that take place in the fish muscle following metal exposure and toxicity.

Adaptation of the fish juvenile growth test (OECD TG 215, 2000) to the marine species Dicentrarchus labrax

The OECD TG 215 method (2000) (C.14 method of EC Regulation 440/2008) was developed on the rainbow trout (Oncorynchus mykiss) to assess chronic toxicity (28d) of chemicals on fish juveniles. It contemplates to use other well documented species identifying suitable conditions to evaluate their growth. OECD proposes the European sea bass (Dicentrarchus labrax, L. 1758) as Mediterranean species among vertebrates recommended in the OECD guidelines for the toxicity testing of chemicals. In this context, our study is aimed to proposing the adaptation of the growth test (OECD TG 215, 2000) to D. labrax. For this purpose toxicity tests were performed with sodium dodecyl sulfate, a reference toxicant commonly used in fish toxicity assays. The main aspects of the testing procedure were reviewed: fish size (weight), environmental conditions, dilution water type, experimental design, loading rate and stocking density, feeding (food type and ration), test validity criteria. The experience gained from growth tests with the sea bass allows to promote its inclusion among the species to be used for the C.14 method.

Chronic Effects of Realistic Concentrations of Non-essential and Essential Metals (Lead and Zinc) on Oxidative Stress Biomarkers of the Mosquitofish, Gambusia holbrooki

Metallic contamination is widespread, particularly in areas impacted by human activities. Human activities result in high loads of metals being discarded into the aquatic compartment, reinforcing the need to evaluate their toxic effects especially on exposed fish. The purpose of this study was to determine the toxic response (namely, antioxidant levels and lipoperoxidative damage) in both liver and gills of the freshwater fish species Gambusia holbrooki, exposed to lead and zinc. Fish were exposed for 28 days (chronic exposure) to ecologically relevant concentrations of the selected compounds. The following oxidative stress/damage biomarkers were evaluated: glutathione-S-transferases (GSTs), glutathione reductase (GR), and thiobarbituric acid reactive substances (TBARS). The results indicate that lead caused a significant oxidative response, with significant increase of the enzymatic antioxidant defense (GSTs activity in hepatic tissue, and GR activity in branchial tissue) of exposed organisms. On the other hand, zinc caused a significant inhibition of G. holbrooki hepatic GR, a biological response that may be related to the antioxidant activity exhibited by this metal. The obtained results are of high importance, especially if one considers that the obtained toxic responses occurred at low, albeit ecologically relevant, levels of exposure.

Glutathione S-transferase activities in African catfish injected with β-naphthoflavone: effects of ploidy, gender, dose, and sampling time

Glutathione S-transferases (GST) are considered among the most controversial biomarkers of water pollutants in fish with little known about factors influencing their activities. The objective of this study was to investigate how gender, dose, ploidy, and sampling time alter hepatic GST activities in African catfish (Clarias gariepinus) following β-naphthoflavone (β-NF) injection. Newly matured male and female diploid and triploid fish were intraperitoneally (i.p.) injected with 0, 15, or 75 mg/kg of β-NF, and livers were excised 24, 48, and 72 h post-injection. Results showed that hepatic GST activities were significantly inhibited by both doses of β-NF. Inhibition was greater in females than males, but no significant differences were observed between diploid and triploid fish. Enzymatic activities differed over time with lowest levels 72 h post-injection. These results extend our understanding of GST activity in fish and highlight the necessity of considering confounding factors when comparing different studies.

Perturbations in ROS-related processes of the fish Gambusia holbrooki after acute and chronic exposures to the metals copper and cadmium

Metallic contamination is a widespread phenomena, particularly in areas impacted by human activities, and has become a relevant environmental concern. However, the toxicity of metals on fish requires full characterization in terms of short- and long-term effects. Thus, the purpose of this study was to determine the acute and chronic oxidative stress response in liver and gills of Gambusia holbrooki exposed to copper and cadmium. To assess the effects of these two metals, we adopted a strategy of analyzing the pollution effects caused by salts of the two metallic elements, and we quantified the oxidative stress biomarkers catalase, glutathione reductase, glutathione-S-transferases, and lipid peroxidation after exposure (4 and 28 days) to ecologically relevant concentrations, thus simulating actual conditions of exposure in the wild. Our results showed that copper elicited strong effects in all tested biomarkers for both acute and chronic challenges. Cadmium caused a similar response and was shown to cause significant changes particularly in catalase and glutathione-S-transferases activities. These findings evidence that ecologically relevant concentrations of common anthropogenic contaminants are causative agents of serious imbalances (namely oxidative stress) that are likely to trigger life-threatening events.

Determination of pesticide residues in fish tissues by modified QuEChERS method and dual-d-SPE clean-up coupled to gas chromatography-mass spectrometry

The aim of this research was to modify the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the determination of organochlorine and organophosphate pesticides in fatty animal matrices such as fish muscle tissues of carp and sturgeon collected from Carp Valley, Lesser Poland. Pesticides extraction effectiveness was evaluated at 0.030 mg kg(-1) spiking level and efficiency of the dispersive-solid-phase extraction (d-SPE) clean-up step was evaluated by comparison testing two different d-SPE clean-up stages, first the addition of the d-SPE sorbent combination (PSA + SAX + NH2), and secondly the addition of C18 after extracts enrichment with the d-SPE sorbent combination (PSA + SAX + NH2), introducing a novel concept of clean-up named dual-d-SPE clean-up. Analysis of pesticide residues was performed by Gas Chromatography Quadrupole Mass Spectrometry (GC/Q-MS) working in selected-ion monitoring (SIM) mode. Linear relation was observed from 0 to 200 ng mL(-1) and determination coefficient R(2) > 0.997 in all instances for all target analytes. Better recoveries and cleanliness of extracts in both samples, carp and sturgeon tissues, were obtained after C18 addition during the dual-d-SPE clean-up step. Recoveries were in the range 70-120%, with relative standard deviation lower than 10% at 0.030 mg kg(-1) spiking level for most pesticides. LODs ranged 0.001-0.003 mg kg(-1), while LOQs ranged 0.004-0.009 mg kg(-1). The proposed method was successfully applied analyzing pesticide residues in real carp and sturgeon muscle samples; detectable pesticide residues were observed, but in all of the cases contamination level was lower than the default maximum residue levels (MRLs) set by the European Union (EU), Regulation (EC) N 396/2005.

Influence of titanium dioxide nanoparticles on 2,3,7,8-tetrachlorodibenzo-p-dioxin bioconcentration and toxicity in the marine fish European sea bass (Dicentrarchus labrax)

The present study investigated the influence of nano-TiO(2) (1 mg L(-1)) on 2,3,7,8-tetrachlorodibenzo-p-dioxin(2,3,7,8-TCDD) (46 pg L(-1)) bioconcentration and toxicity in the European sea bass (Dicentrarchus labrax) during 7 days in vivo exposure. A multimarkers approach was applied in different organs: detoxification in liver; innate immunity and pro-inflammatory response and adaptive immunity in gills and spleen; genotoxicity in peripheral erythrocytes and muscle. Bioconcentration of 2,3,7,8-TCDD in presence of nano-TiO2 was investigated in liver, skin and muscle as well as interaction between nano-TiO2 and organic pollutants in artificial sea water (ASW). Nano-TiO2 negatively influenced immune response induced by 2,3,7,8-TCDD in spleen but not in gills and reduced the DNA damage induced by 2,3,7,8-TCDD in erythrocytes. nano-TiO2 did not interfere with 2,3,7,8-TCDD detoxification and bioconcentration according to the observed no interaction of the nano-TiO2 with organic pollutants in ASW.

EROD activity and antioxidant defenses of sea bass (Dicentrarchus labrax) after an in vivo chronic hydrocarbon pollution followed by a post-exposure period

Chronic concentrations of polycyclic aromatic hydrocarbons (PAHs) have been commonly detected in international estuaries ecosystems. Reliable indicators still need to be found in order to properly assess the impact of PAHs in fish. After an in vivo chronic exposure to hydrocarbons, the enzymatic activity of 7-ethoxyresorufin O-deethylase (EROD) and the antioxidant defense system were assessed in sea bass, Dicentrarchus labrax. A total of 45 fish were exposed to the water-soluble fraction of Arabian crude oil, similar to a complex pollution by hydrocarbons chronically observed in situ, while 45 other control fish sustained the same experimental conditions in clean seawater. Fish samples were made after a 21-day exposure period and after a 15-day recovery period in clean fresh water. Throughout the experiment, liver EROD activity was significantly higher in contaminated fish than in control fish. In addition, nonenzymatic (total glutathione) and enzymatic (GPx, SOD, and CAT) antioxidant defense parameters measured in liver were not significantly different in fish. Furthermore, in gills, glutathione content had significantly increased while SOD activity had significantly decreased in contaminated fish compared to controls. On the other hand, CAT and GPx activities were not affected. Chronic exposure to PAHs disturbing the first step (SOD) and inhibiting the second step (GPx and CAT) could induce oxidative stress in tissues by the formation of oxygen radicals. After the postexposure period, there was no significant difference between control and contaminated fish in any of the antioxidant defense parameters measured in gills, attesting to the reversibility of the effects.

Induction of CYP1A and ABC transporters in European sea bass (Dicentrarchus labrax) upon 2,3,7,8-TCDD waterborne exposure

The aim of this study was to characterize the responsiveness of CYP1A and ABC transport proteins in European Sea bass (Dicentrarchus labrax) waterborne exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) (46 pg/L) for 24 h and 7 days. Genes modulation (abcb1, abcc1-2, cyp1a), EROD activity were investigated in liver and 2,3,7,8-TCDD bioconcentration in liver and muscle. TCDD induced significantly cyp1a gene expression and EROD activity at 24 h and 7 d. A significant up-regulation of abcb1 was also observed but only after 7 days. No modulation of abcc1 and abcc2 genes was observed. Waterborne TCDD exposure was able to induce CYP1A and abcb1 encoding for P-glycoprotein in juvenile of European sea bass.

Wild boar (Sus scrofa) as a bioindicator of organochlorine compound contamination in terrestrial ecosystems of West Pomerania Province, NW Poland

The aim of this study was to detect the presence and determine the residue levels of DDT, lindane, endrin and polychlorinated biphenyls (PCBs) in the liver of wild boars from the area of West Pomerania, NW Poland; to determine the activity of glutathione S-transferase (GST) as a biomarker of biological response and to assess the toxicological risk for consumers of the wild boar offal. The presence of pesticide residues and PCBs was found in all examined liver samples. The highest concentration was observed for endrin, and then, the descending order was PCBs >DDTs >lindane >dl-PCBs. The mean hepatic concentrations of endrin, PCBs, DDTs and lindane were 117.28, 78.59, 67.95 and 7.24 ng/g lipid weight, respectively. Among the dioxin-like PCB congeners, 118 and 156 were dominant in liver samples. The mean toxic equivalent (TEQ) level calculated for dl-PCBs was 2.10 ± 1.11 pg WHO-PCB-TEQ/g. There was a statistically significant (p < 0.05) negative correlation between the concentration of lindane, DDTs and PCBs (as a sum of indicator congeners) in the liver and in the activity of GST. However, GST activities showed no significant correlation with any of the dl-PCBs. In five boar liver samples, the levels of certain organochlorine compounds exceeded the maximum residue levels (MRLs). In one sample, the MRLs were exceeded simultaneously for PCBs, endrin and DDTs and in another one-for endrin and DDTs. In the remaining three samples, only PCB levels were exceeded.

Biochemical responses in seabream (Sparus aurata) caged in-field or exposed to benzo(a)pyrene and paraquat. Characterization of glutathione S-transferases

Gilthead seabream (Sparus aurata) specimens were caged in-field at the Téboulba harbour or exposed to benzo(a)pyrene [B(a)P] or to paraquat [PQ] plus B(a)P, and several biochemical biomarker responses were investigated. Antioxidant enzymes, such as glutathione peroxidase, catalase and glutathione reductase, significantly increased in the in-field and B(a)P+PQ exposures, but were only moderately affected by B(a)P alone. Glucose-6-phosphate and 6-phosphogluconate dehydrogenases significantly diminished after in-field exposure. Different responses with biotransformation enzymes were observed: the P4501A-associated EROD activity was highly induced in response to B(a)P and B(a)P+PQ exposures, while total activity of the glutathione S-transferase (GST) was similar to control. However, after purification of the GST proteins by affinity chromatograpy and analysis by two-dimensional electrophoresis, nineteen highly reproducible isoforms were resolved. In addition, some of reproducible isoforms showed different and specific expression patterns in response to contaminants. Thus, proteomic analysis of the purified GST subunits is a reliable tool for ecotoxicological research, useful in polluted marine ecosystem as an effective biomarker of contamination.

Occurrence of polybrominated diphenyl ethers, polychlorinated biphenyls, and phthalates in freshwater fish from the Orge river (Ile-de France)

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and phthalates were investigated from July 2009 to April 2010 in three fish species from the Orge river, which flows in a densely populated area of Ile-de-France. In two Cyprinidae (roach and chub) and one Percidae (perch), muscle contents in increasing order ranged as follows: 12-18 ng g(-1) dw for PBDEs (Σtri-hepta), 120-170 ng g(-1) dw for PCBs (Σ7), and 2,250-5,125 ng g(-1) dw for phthalates (Σ7). No variation was observed between contaminant contents and lipid levels. No biomagnification was found according to the trophic level for PBDEs and PCBs, whereas for phthalates the highest contents were found in perch. Seasonal variations were observed with the lowest PBDE and PCB contents occurring in July after spawning in roach and perch (p < 0.001). PBDE content followed a decreasing trend-gonad > liver > muscle-whatever the period. For PCBs, gonad and liver contents remained greater than that of muscle (p < 0.05). Our results indicate a preferential accumulation of halogenated compounds in gonad and liver outside the reproduction period. Bioaccumulation factors for PCBs in muscle were significantly correlated to their chlorination degree in perch (p < 0.01) and roach (p < 0.01). In roach, that correlation slope was by decreasing importance order as follows: gonad > liver > muscle. The biota-sediment accumulation factors varied from 0.1 to 29.2, from 1.6 to 4.8, and from 1 to 123.5 for PBDEs, PCBs, and phthalates, respectively. These results contribute to document the use of freshwater fish as bioindicators of river quality.

Evaluation of spatial and temporal changes in biomarker responses in the common carp (Cyprinus carpio L.) for biomonitoring the Meriç Delta, Turkey

The aim of this study is to examine the activity of several biomarkers in carp, Cyprinus carpio L., to determine their response to xenobiotics, such as organochlorine pesticides (OCPs), in the Meriç Delta. Fish were collected from contaminated sites and from areas regarded as relatively less contaminated in four sampling periods. Hepatic glutathione S-transferase (GST), carboxylesterase (CaE), lactate dehydrogenase, aspartate aminotransferase, and acid phosphatase activities were measured as biomarkers in the fish. For all fish, the condition factor and hepatosomatic index, were calculated to determine the condition of the fish. The results of this study indicated that the mean GST activity showed an increase in fish from the Meriç-Ergene junction site and a decrease in Enez site with respect to fish from Meriç site. Furthermore, the study shows that spatial and temporal changes of biomarkers such as GST and CaE might be useful for the assessment of environmental contamination in the Meriç Delta.

Organochlorine pesticides and polychlorinated biphenyls in sediments and fish from freshwater cultured fish ponds in different agricultural contexts in north-eastern France

Organochlorine pesticides (HCB, HCH with α-, β-, and γ isomers, heptachlor, cis-heptachlor epoxyde, trans-heptachlor epoxyde, endosulfan with α- and β isomers, sulfate endosulfan, o,p'-DDT, p,p'-DDT, o,p'-DDE, p,p'-DDE, o,p'-DDD, p,p'-DDD, chlorothalonil, alachlor, aldrin, dieldrin, methoxychlor, oxychlordane, chlordane with α- and γ isomers, p,p'-dicofol and o,p'-dicofol) and indicators PCBs (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) were studied both in sediments and muscles of farmed fish species (Cyprinus carpio and Perca fluviatilis). Samples were collected from fish ponds located in the hydrographic basin of the Moselle River (Lorraine Region, France). OCPs and PCBs were present at low concentrations both in sediments and fish muscles. Concerning sediments, ∑DDTs revealed concentrations ranging from 0.2 to 2.30 ng g(-1) dw and ∑PCBs ranged from 0.3 to 3.5 ng g(-1) dw. Concerning fish muscles, the highest concentrations in OCPs were those of p,p'-DDE, with average concentrations of 0.57±0.44 ng g(-1) ww for carp and 0.58±0.29 ng g(-1) ww for perch. The contamination profiles proved to be different depending on the fish species. Indeed, HCH-isomers, HCB, and dieldrin were detected only for the carp and always at low concentrations. For example, the highest concentration of HCHs was observed for β-HCH with a mean value of 0.64±0.15 ng g(-1) ww for carp. As for PCBs, the levels of ∑PCBs ranged from 0.3 to 6.4 ng g(-1) ww in carp muscles and from 0.90 to 5.60 ng g(-1) ww in perch muscles.

Identification of a puromycin-sensitive aminopeptidase from zebrafish (Danio rerio)

An aminopeptidase from zebrafish (Danio rerio) was purified 1247-fold to homogeneity with 35.4% recovery by column chromatography successively on DEAE-sephacel, hydroxyapatite, and phenyl-sepharose. The molecular mass of the enzyme was estimated at 98 kDa by SDS-PAGE and gel filtration. Optimum temperature and pH of the enzyme were 45°C and 7.5, respectively. The enzyme preferentially hydrolyzed substrate Leu-MCA with k(cat)/K(m) of 4.2×10(6)M(-1)s(-1) and an activation energy of 68.9 kJ M(-1) [corrected], respectively. It was specifically inhibited by bestatin, puromycin and metal-chelating agents, and Zn(2+) seemed to be its metal cofactor(s). Some l-amino acids significantly inhibited its activity, and l-cysteine was a non-competitive inhibitor with a K(i) of 0.27 mM. According to the peptide mass fingerprint analysis, the enzyme was highly matched with the predicted D. rerio aminopeptidase puromycin sensitive (gi: 255683530) (EC 3.4.11.14), suggesting that the present enzyme is a puromycin-sensitive aminopeptidase of zebrafish.

Assessment of contaminants and biomarkers of exposure in wild and farmed seabass

This study aimed to investigate the relationships between levels of organochlorine compounds (PCBs and DDTs), polycyclic aromatic hydrocarbons (PAHs), metals and biomarkers of exposure (EROD and GST) and oxidative stress biomarkers, in wild and cultured European seabass (Dicentrarchus labrax). Additionally, the fatty acid profile was determined in muscle to assess differences between cultivated and wild specimens of marketable size. Although results pointed to relatively low concentration of contaminants, wild specimens presented enhanced accumulation of metals and cultivated specimens higher levels of organic compounds. Biomarkers were correlated with contaminants in tissues, showing that higher levels can cause effects at the biochemical level. Wild specimens have presented higher content on omega-3 fatty acids in muscle. Besides the useful application of biomarkers in wild species, this study has shown that they can also be applied to monitor biological effects in the fish farming process.