Monitoring biological effects of contamination in marine fish along French coasts by measurement of ethoxyresorufin-O-deethylase activity

Biliary polycyclic aromatic hydrocarbons and enzymatic biomarkers in Eugerres brasilianus along four tropical estuaries

Polycyclic aromatic hydrocarbons (PAH) in bile and biochemical biomarkers were evaluated in Brazilian mojarra Eugerres brasilianus along four estuaries in northeastern Brazil. Bile PAHs naphthalene, phenanthrene chrysene, pyrene and benzo[a]pyrene were lowest at Formoso River Estuarine System (FRES), an area with low population density focused on tourism. Fish sampled in Suape Estuarine Complex (SEC), where a growing industrial port complex is established indicated higher naphthalene and pyrene concentrations compared with FRES. Fish sampled in highly urbanized and populated Bacia do Pina Estuarine Complex (BPEC) and Barra de Jangada Estuarine System (BJES) indicated an increase in all PAHs compared to FRES. Activities of phase 1 Ethoxyresorufin-O-deethylase, phase 2 glutathione-S-transferase and antioxidant defense catalase were induced up to 20, 2 and 2-fold in BJES and BPEC compared to FRES. This study confirms E. brasilianus as an important sentinel species, providing baseline information for these tropical estuaries with different degrees of anthropogenic pressure.

Integrated monitoring of chemicals and their effects on four sentinel species, Limanda limanda, Platichthys flesus, Nucella lapillus and Mytilus sp., in Seine Bay: A key step towards applying biological effects to monitoring

The International workshop on Integrated Assessment of CONtaminants impacts on the North sea (ICON) provided a framework to validate the application of chemical and biological assessment thresholds (BACs and EACs) in the Seine Bay in France. Bioassays (oyster larval anomalies, Corophium arenarium toxicity assay and DR Calux) for sediment and biomarkers: ethoxyresorufin-O-deethylase (EROD) activity, acetylcholinesterase (AChE) activity, lysosomal membrane stability (LMS), DNA strand breaks using the Comet assay, DNA adducts, micronucleus (MN), PAH metabolites, imposex, intersex and fish external pathologies were analysed in four marine sentinel species (Platichthys flesus, Limanda limanda, Mytilus sp. and Nucella lapilus). Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and heavy metals were analysed in biota and sediment. Results for sediment and four species in 2008-2009 made it possible to quantify the impact of contaminants using thresholds (Environmental Assessment Criteria/EAC₂₀₀₈: 70% and EAC₂₀₀₉: 60%) and effects (EAC₂₀₀₈: 50% and EAC₂₀₀₉: 40%) in the Seine estuary. The Seine estuary is ranked among Europe's most highly polluted sites.

Use of metallothioneins as biomarkers for environmental quality assessment in the Gulf of Gabès (Tunisia)

Detection and assessment of the impact of pollution on biological resources imply increasing research on early-warning markers such as metallothioneins (MTs) in metal exposure. In this paper, we have collated published information on the use of metallothioneins and metallothionein-like proteins (MTLPs) as biomarkers for environmental quality assessment in the Gulf of Gabès. In this area, some species of fish and bivalve were used as bioindicators of pollution. In these species, an induction of MTs/MTLPs by the essential metals such as Cu and Zn and the non-essential metals such as Cd was observed by different authors who suggest the potential use of these proteins as biomarkers. However, MT concentrations can be influenced by many biotic (sex, maturity stages, and tissues) and abiotic factors (temperature, salinity, and pH). This is essentially the case in field studies where many parameters can randomly affect MT levels, so the endogeneous regulation of MTs must be considered before using MTs as an indicator of heavy metal exposure. Moreover, the use of biomarker cannot be examined independently of the evaluation of techniques that enable its quantification. Therefore, the approach to the use of MTs/MTLP as biomarkers of exposure for an assessment of the physiological status of aquatic organisms is discussed in this paper.

Hepatic biotransformation genes and enzymes and PAH metabolites in bile of common sole (Solea solea, Linnaeus, 1758) from an oil-contaminated site in the Mediterranean Sea: a field study

The aim of the present field study was to evaluate the response of hepatic biotransformation genes and enzymes of the common sole collected from an area characterized by the presence of an oil-refinery. Based on ∑PAHs levels detected in sediments, three sites were identified: an high-impact site in front of the refinery, a moderate impact site and a reference site at increasing distances from the refinery. Transcription of cyp1a, udpgt and gst genes and related enzyme activities, such as EROD, BROD, MROD, B(a)PMO, UDPGT and GST, were assessed in sole liver. PAHs bile metabolites were measured. The link between phases I and II is discussed with regard to levels of PAHs measured in sediments and fillets. Results provide sequencing data on biotransformation genes essential for further studies on transcriptional responses in common sole and confirm phase I enzyme activities as useful tools for future biomonitoring studies in marine coastal areas.

Transcriptional and post-transcriptional response of drug-metabolizing enzymes to PAHs contamination in red mullet (Mullus barbatus, Linnaeus, 1758): a field study

Aim of this study was to evaluate the responsiveness of red mullet (Mullus barbatus) liver detoxification enzymes to PAHs at transcriptional and post-transcriptional levels in the field. Fish were captured in the north-eastern Adriatic Sea, close to an oil refinery. Sixteen PAHs (EPA) were determined in sediments and fish fillets; transcription levels of cyp1a, cyp3a and abcc2 genes and EROD, BROD, B(a)PMO, BFCOD, GST and UDPGT enzymatic activities were measured. Levels of PAHs in sediments reflect the oil pollution gradient of the area, with weak correspondence in fish fillets. cyp1a gene transcription and EROD, B(a)PMO and BFCOD activities were significantly induced in the oil refinery site, and a slight up-regulation of cyp3a and abcc2 was also observed. GST and UDPGT remained unchanged. The present study provides the first data on detoxification responses at transcriptional levels in the liver of red mullet and confirms phase I enzymes as suitable biomarkers of exposure to PAHs in field studies.

Alterations in respiration rate of isolated rainbow trout hepatocytes exposed to the P-glycoprotein substrate rhodamine 123

Reducing intracellular xenobiotic concentration is an important defence strategy used by cells challenged with foreign chemicals. One mechanism used to achieve this goal is via the use of P-glycoproteins (P-gps), ATP-dependent transporters that mediate the removal of hydrophobic compounds from cells. The energetic costs of this mechanism are unknown, therefore, the activity and respiratory costs associated with the P-gp-mediated efflux of rhodamine 123 (R123) was measured in isolated rainbow trout hepatocytes. The accumulation of R123 was rapid and concentration-dependent. Initial accumulation rates were 1.79+/-0.41, 7.29+/-1.06 and 15.30+/-1.74ngR123/min/10(6)cells when exposed to 1, 5 and 10 microM R123, respectively. Efflux was measured in cells 'pre-loaded' with R123 at each concentration, resulting in initial efflux rates of 0.77+/-0.12, 2.02+/-0.35 and 3.51+/-0.84ngR123/min/10(6)cells, respectively. The baseline oxygen consumption rate of hepatocytes was 33.21+/-1.09 ng O2/min/10(6)cells. Respiration rates were significantly higher in cells exposed to 5 and 10 microM R123 (39.08+/-0.80 and 41.72+/-0.61ng O2/min/10(6)cells), representing increases over basal rates of 18.5 and 25.7%, respectively. Measurements of isolated mitochondrial respiration established that changes in hepatocyte oxygen consumption were not through the direct effects of R123 on mitochondria. The P-gp inhibitor, XR9576 significantly inhibited R123 efflux from cells with a concomitant return of respiration rates to baseline values. This study demonstrates that increased P-gp transport of xenobiotics can significantly raise cellular respiration rates and may result in higher energy costs for organisms living in P-gp-substrate contaminated environments.

Fish bioaccumulation and biomarkers in environmental risk assessment: a review

In this review, a wide array of bioaccumulation markers and biomarkers, used to demonstrate exposure to and effects of environmental contaminants, has been discussed in relation to their feasibility in environmental risk assessment (ERA). Fish bioaccumulation markers may be applied in order to elucidate the aquatic behavior of environmental contaminants, as bioconcentrators to identify certain substances with low water levels and to assess exposure of aquatic organisms. Since it is virtually impossible to predict the fate of xenobiotic substances with simple partitioning models, the complexity of bioaccumulation should be considered, including toxicokinetics, metabolism, biota-sediment accumulation factors (BSAFs), organ-specific bioaccumulation and bound residues. Since it remains hard to accurately predict bioaccumulation in fish, even with highly sophisticated models, analyses of tissue levels are required. The most promising fish bioaccumulation markers are body burdens of persistent organic pollutants, like PCBs and DDTs. Since PCDD and PCDF levels in fish tissues are very low as compared with the sediment levels, their value as bioaccumulation markers remains questionable. Easily biodegradable compounds, such as PAHs and chlorinated phenols, do not tend to accumulate in fish tissues in quantities that reflect the exposure. Semipermeable membrane devices (SPMDs) have been successfully used to mimic bioaccumulation of hydrophobic organic substances in aquatic organisms. In order to assess exposure to or effects of environmental pollutants on aquatic ecosystems, the following suite of fish biomarkers may be examined: biotransformation enzymes (phase I and II), oxidative stress parameters, biotransformation products, stress proteins, metallothioneins (MTs), MXR proteins, hematological parameters, immunological parameters, reproductive and endocrine parameters, genotoxic parameters, neuromuscular parameters, physiological, histological and morphological parameters. All fish biomarkers are evaluated for their potential use in ERA programs, based upon six criteria that have been proposed in the present paper. This evaluation demonstrates that phase I enzymes (e.g. hepatic EROD and CYP1A), biotransformation products (e.g. biliary PAH metabolites), reproductive parameters (e.g. plasma VTG) and genotoxic parameters (e.g. hepatic DNA adducts) are currently the most valuable fish biomarkers for ERA. The use of biomonitoring methods in the control strategies for chemical pollution has several advantages over chemical monitoring. Many of the biological measurements form the only way of integrating effects on a large number of individual and interactive processes in aquatic organisms. Moreover, biological and biochemical effects may link the bioavailability of the compounds of interest with their concentration at target organs and intrinsic toxicity. The limitations of biomonitoring, such as confounding factors that are not related to pollution, should be carefully considered when interpreting biomarker data. Based upon this overview there is little doubt that measurements of bioaccumulation and biomarker responses in fish from contaminated sites offer great promises for providing information that can contribute to environmental monitoring programs designed for various aspects of ERA.

Integrated biomarker response: a useful tool for ecological risk assessment

A battery of biomarkers is often used to evaluate the effects of exposure to chemical contaminants and detect responses to environmental stress. Unfortunately, field application of biomarkers is subject to various constraints (e.g., the availability of living material) that can limit data acquisition and prevent the use of multivariate methods during statistical analysis. In these circumstances, a simple method is needed to summarize biomarker responses and simplify their interpretation in biomonitoring programs. The present study used star plots to display results for the panel of biomarkers used for each station and survey. Integrated biomarker response (IBR) was then computed as the star plot area. Star plots using IBR values instead of biomarker data make it possible to visualize between-site and/or between-survey differences for comparison with exposure conditions. This approach was applied to sites in the Baltic Sea and the Seine Estuary, English Channel. In both cases, IBR values were visually compared to polycyclic aromatic hydrocarbons (PAH) or polychlorobiphenyls (PCB) levels measured in mussel or fish tissues. The IBR, as an indicator of environmental stress, appears to be a useful tool for scientists and managers in assessing ecological risk.

Enhanced xenobiotic transporter expression in normal teleost hepatocytes: response to environmental and chemotherapeutic toxins

Many aquatic organisms are resistant to environmental pollutants, probably because their inherent multi-drug-resistant protein extrusion pump (pgp) can be co-opted to handle man-made pollutants. This mechanism of multixenobiotic resistance is similar to the mechanism of multidrug resistance exhibited in chemotherapy-resistant human tumor cells. In the present study, a variety of techniques were used to characterize this toxin defense system in killifish (Fundulus heteroclitus) hepatocytes. The cellular localization and activity of the putative drug efflux system were evaluated. In addition, in vitro and in vivo studies were used to examine the range of expression of this putative drug transporter in the presence of environmental and chemotherapeutic toxins. The broad range of pgp expression generally observed in transformed mammalian cells was found in normal cells of our teleost model. Our findings suggest that the expression of the pgp gene in the killifish could be an excellent indicator of toxin levels or stressors in the environment.

Application of the ethoxyresorufin-O-deethylase (EROD) assay to mixtures of halogenated aromatic compounds

The ethoxyresorufin-O-deethylase (EROD) assay monitors the induction of the xenobiotic-metabolizing enzyme cytochrome P-450 (CYP) 1A1 and is a widely used biomarker for exposure of wildlife to substances that bind the aryl hydrocarbon (Ah) receptor. In this work the induction of EROD activity by single compounds and binary mixtures in primary rat hepatocytes was compared with the predictions of a kinetic model involving mixtures of inducers. The inducing agents were also examined for their ability to activate the Ah receptor to its DNA-binding form and for their ability to act as competitive inhibitors for CYP 1A1. Xenobiotics that failed to activate the Ah receptor did not induce EROD activity. Competitive inhibition for CYP 1A1 between the xenobiotic and 7-ethoxyresorufin caused EROD activity to fall at high xenobiotic concentrations. Competition for a limited number of Ah receptor sites depressed the EROD activity of a strong inducer such as 2,3,7,8-tetrachlorodibenzo-p-dioxin at high concentrations of a weak inducer. Application of the kinetic model to the example of a mixture of low concentrations of dibenzo-p-dioxins and much higher concentrations of polychlorinated biphenyls indicated that EROD assays often seriously underestimate the true potency of an environmental sample. Hence the EROD assay cannot be used for determining dioxin equivalent concentrations using the toxic equivalence factor approach.

EROD activity measured in flatfish from the area of the Sea Empress oil spill

Dab (Limanda limanda) and plaice (Pleuronectes platessa) were collected at five stations near to the site of the Sea Empress oil spill within two weeks of the incident and a further fourteen stations three months after the spillage. Ethoxyresorufin-O-deethylase (EROD) activity was determined in the livers of the specimens to determine whether induction could be detected. Statistically significant inter-site differences in EROD levels in both species were demonstrated. Elevated levels of EROD activity in dab were found at the two stations nearest to the incident up to three months after the spill but no clear relationship to putative contaminant levels was determined. EROD levels in plaice showed a generally similar pattern of induction as in dab. Correlation of EROD levels with other variables showed that sexual maturity had the greatest influence on dab during the study period. The plaice specimens were sexually immature and, therefore, did not demonstrate a corresponding relationship. It was concluded that, for EROD monitoring purposes, fish should be sampled during their sexually inactive phase and that close attention needs to be paid to other variables (depth, temperature, GSI, length, influential contaminants etc.) when interpreting the results.