The integrated use of chemical analysis, cytochrome P450 and stress proteins in mussels to assess pollution along the Galician coast (NW Spain)

Molecular and biochemical biomarkers in the American oyster Crassostrea virginica exposed to herbicide Roundup® at high temperature

Aquatic organisms are frequently exposed to various environmental stressors. Thus, the effects of high temperatures and herbicides on aquatic organisms are a major subject of interest. In this study, we studied the effects of short-term exposure (1 week) to Roundup®, a glyphosate-based herbicide (concentrations: 0.5 and 5 µg/L), on the morphology of gills, digestive glands, and connective tissues, and the expression of heat shock protein-70 (HSP70, a chaperone protein), cytochrome P450 (CYP450, a biomarker of environmental contaminants), dinitrophenyl protein (DNP, a biomarker of protein oxidation), nitrotyrosine protein (NTP, a biomarker of protein nitration), antioxidant enzymes such as superoxidase dismutase (SOD) and catalase (CAT) in tissues of American oyster, Crassostrea virginica (Gmelin, 1791) maintained at high temperature (30 °C). Histological analyses showed an increase in mucous production in the gills and digestive glands, and in hemocyte aggregation in the connective tissues as well as a structural change of lumen in the digestive glands of oysters exposed to Roundup. Immunohistochemical and quantitative RT-PCR analyses showed significant (P < 0.05) increases in HSP70, CYP450, DNP, NTP, CAT, and SOD mRNA and protein expressions in the tissues of oysters exposed to Roundup. Taken together, these results suggest that exposure to Roundup at high temperature induces overproduction of reactive oxygen species/reactive nitrogen species which in turn leads to altered prooxidant-antioxidant activity in oyster tissues. Moreover, our results provide new information on protein oxidation/nitration and antioxidant-dependent mechanisms for HSP70 and CYP450 regulations in oysters exposed to Roundup at high temperature.

First characterization of the ecotoxicity of paraffin particles: assessment of biochemical effects in the marine polychaete Hediste diversicolor

Plastics are a widespread environmental problem, particularly in the form of small particles or fragments (microplastics). With the purpose of gradually replacing the use of plastics in cosmetic products (primary microplastics), the use of paraffin in microspheres has recently been applied. Paraffin waxes are composed by organic molecules usually derived from petroleum, thus assumed to be chemically and biologically inert, having a lower (eco)toxicity and residence time compared with plastic particles. However, the low ecotoxicity of paraffin waxes may be somewhat questionable, because some paraffin constituents can be absorbed and catabolized, thus exerting biological effects. The main objective of this study was to understand the potential toxic effects of paraffin microparticles on key physiological processes of the polychaete Hediste diversicolor. To attain this objective, this work assessed the acute and chronic effects of three densities (5, 20, and 80 mg L^-1) of four size ranges of paraffin particles (from 100 to 1200 μm) on this epibenthic organism. Although paraffin wax can be generically considered innocuous, the present study was able to demonstrate a significant inhibition in the activity of acetylcholinesterase in acutely exposed organisms and an increase in the activity of glutathione peroxidase, catalase, and glutathione S-transferase under some specific scenarios.

Expression patterns of heat shock protein genes in Rita rita from natural riverine habitat as biomarker response against environmental pollution

River pollution is one of the principal environmental concerns and biomonitoring tools can play an important role in pollution assessment in the riverine environment. Heat shock proteins (Hsps) have been found to be suitable tools for monitoring stress response. In the present study, expression analyses of hsp genes (hsp27, hsp47, hsp60, hsp70, hsc70, and hsp90) and selected hsp-regulatory genes (hsf1, hyou1, ask1, jnk) were carried out by RT-qPCR in catfish Rita rita collected from selected stretches of river Ganga to investigate changes in their expression patterns as biomarker response. Water quality characteristics were measured in terms of physico-chemical characteristics (DO, BOD, COD, pH, conductivity), element profile (arsenic, mercury, cadmium, lead, chromium, zinc, copper) and persistent organic pollutants (POPs; HCH, DDT, aldrin, endosulphan, heptachlor). Water quality index was calculated and sampling sites were categorized as good/medium/bad. Multivariate analysis was carried out taking the water quality parameters and the fold changes in hsp gene expression as variables, which showed that hsp47 and hsp70b correlated well with BOD, an indicator of organic pollution. To identify the organic pollutant(s) which could be influencing the expression of hsps, again multivariate analysis was employed taking concentration of POPs and fold changes of hsps, which showed up-regulation of hsp47 and hsp70b (HSP72i) correlated well with concentrations of aldrin and HCH. Synergistic effects of these POPs could be responsible for the up-regulation of said hsps, although individually present in low concentration; thus, indicating synergistic effect of the POPs on hsp47 and hsp70b up-regulation as biomarker response.

Gene expression profiling reveals deep-sea coral response to the Deepwater Horizon oil spill

Deep-sea coral communities are key components of the Gulf of Mexico ecosystem and were adversely affected by the Deepwater Horizon (DWH) oil spill. Coral colonies exposed to oil and dispersant exhibited mortality, damage and physiological signatures of stress. Understanding how corals respond to oil and dispersant exposure at the molecular level is important to elucidate the sublethal effects of the DWH disaster and reveal broader patterns of coral stress responses. Gene expression profiles from RNAseq data were compared between corals at an impacted site and from a reference site. A total of 1,439 differentially expressed genes (≥twofold) were shared among impacted Paramuricea biscaya colonies. Genes involved in oxidative stress, immunity, wound repair, tissue regeneration and metabolism of xenobiotics were significantly differentially expressed in impacted corals. Enrichment among the overexpressed genes indicates the corals were enduring high metabolic demands associated with cellular stress responses and repair mechanisms. Underexpression of genes vital to toxin processing also suggests a diminished capacity to cope with environmental stressors. Our results provide evidence that deep-sea corals exhibited genome-wide cellular stress responses to oil and dispersant exposure and demonstrate the utility of next-generation sequencing for monitoring anthropogenic impacts in deep waters. These analyses will facilitate the development of diagnostic markers for oil and dispersant exposure in deep-sea invertebrates and inform future oil spill response efforts.

Effects of endocrine disrupting chemicals on estrogen receptor alpha and heat shock protein 60 gene expression in primary cultures of loggerhead sea turtle (Caretta caretta) erythrocytes

The loggerhead turtle (Caretta caretta) can be considered a good indicator species for studying the ecological impact of endocrine disrupting chemicals (EDCs) on wildlife. However, the effect of these environmental pollutants on nuclear steroid hormone signaling has not yet been addressed in sea turtles mainly due to the legal constraints of their endangered status. Here we describe the use of primary erythrocyte cell cultures as in vitro models for evaluating the effects of different EDCs on the expression of estrogen receptor α (ERα). In addition, we evaluated erythrocyte toxicity caused by EDCs using Alamar Blue assay and heat shock proteins 60 (HSP60) expression. Primary cultures of erythrocytes were exposed to increasing concentrations of 4-nonylphenol (4NP), Diisodecyl phthalate (DiDP), Tri-m-cresyl phosphate (TMCP) and Tributyltin (TBT) for 48h. Alamar Blue demonstrated that exposure of erythrocytes to each contaminant for up to 48h led to a significant impairment of cellular metabolic activity at 100μM, with the exception of TBT. Moreover, our data indicate that loggerhead erythrocytes constitutively express ERα and HSP60 at the transcript level and respond to EDCs by up-regulating their expression. In this regard, ERα was up-regulated in a dose-dependent manner after 48h exposure to both 4NP and TMCP. Interestingly, the dosage-dependent effects of DiDP on ERα expression were opposite in comparison to that obtained following exposure to the other tested compounds. This work provides the first indication regarding the potential of primary erythrocytes as study models for evaluating the effects of EDCs on sea turtles.

Assessment of organic micropollutants occurrence in treated wastewater using heat shock protein 47 stress responses in Chinese hamster ovary cells and GC/MS-based non-target screening

Combining bioassays and analytical chemistry screening is a powerful approach to assess organic micropollutants which are the main contributors to toxic potential in complex mixtures of treated wastewater (TWW). The aim of this study was to perform a comprehensive toxicity assessment of treated effluents using stress response bioassays and then to assess the occurrence of the organic micropollutants which were responsible for this biological response using gas chromatography coupled with a mass spectrometry detector (GC/MS). Results showed that TWW samples induced significant stress response on Chinese hamster ovary cells, stably transfected with heat shock protein 47 promoter, at 0.1%, 1%, 5% and 10% concentrations. The organic chemical compounds responsible for stress response potential were identified at different percentage values using non-target chemical screening. Of the compounds detected in TWW1 and TWW4, 55.09% and 74.5% respectively, fell within the class of aliphatic hydrocarbons. Aliphatic hydrocarbons were also present in TWW3 at 26.46% whereas 11.96% corresponded to 6-acetyl-1,1,2,4,4,7-hexamethyltetralin and 16.08% to triethoxysilane. Moreover, 76.73% of TWW2 was recorded as decamethylcyclopentasiloxane (D5) and 17.44% as n-hexadecanoic acid.

Effect of mussel reproductive status on biomarker responses to PAHs: Implications for large-scale monitoring programs

Biomarkers are useful tools to assess biological effects of pollutants and have been extensively used in monitoring programs to determine ecosystem health. In these programs, a wide range of environmental conditions are covered and sometimes, obtained data are difficult to interpret because of natural variables are affecting biomarker responses. Among these variables, musseĺs reproductive status has been considered one of the most changing variables between sites in a monitoring survey. Thus, the main aim of this work was to identify the effect that mussel reproductive status has on biomarker responses. For that purpose, mussels sampled at two periods in the reproductive cycle (reproductive and resting stages) were conditioned to the same laboratory conditions and exposed to fluoranthene (FLU) for three weeks. Studied biomarkers covering a wide range of organism responses were included: bioaccumulation, physiological rates (clearance rate -CR-, absorption efficiency -AE-, respiration rate -RR- and their integration in the scope for growth -SFG-), antioxidant enzyme activities (superoxide-dismutase -SOD-, catalase -CAT-, glutathione reductase -GR-, glutathione peroxidase -GPx-, glutathione-S-tranferase -GST-) and biochemical damage responses (lipid membrane peroxidation -LPO-). The results obtained evidenced that the levels of the biomarkers studied (RR, SOD, CAT and GPx) were higher at reproductive than at resting stage. On the other hand, the effect of toxicant was observed in SFG, CAT and GPx but this effect was only detected during the resting period. Moreover, there was a deterioration of mussel gonadal tissue with FLU exposure during reproductive stage. FLU accumulation in mussel tissues was also dependent of the reproductive status with higher internal concentrations during resting than reproductive period. In conclusion, there was a strong effect of reproductive status on studied biomarkers which seems to mask the effect of FLU at reproductive stage. The present study evidences the need to include the measurement of mussel biological status in marine pollution monitoring programs for a correct interpretation of biomarker data.

Biochemical indicators and biomarkers in chub (Squalius cephalus L.) from the Sava River

Biochemical indicators and biomarkers were analyzed in the liver and gills of chub caught in three localities along the Sava River exposed to different environmental impacts. Sampling sites were: downstream from Zagreb (Zgd), downstream Sremska Mitrovica (SM) and downstream from Belgrade (Bgd). We observed that the relative amounts and levels of activity of Cu, Zn containing superoxide dismutase and glutathione in both the liver and gills, and the relative amounts of heat shock protein (HSP90) and metallothioneins in the gills were highest in the Zgd locality, suggesting a higher impact of metal pollution. The Zgd locality had higher concentrations of trace metals in the water, especially iron. In the SM and Bgd localities, higher relative levels of glutathione peroxidase and catalase were recorded (especially in SM) as compared to the Zgd locality, pointing to the presence of hydrogen peroxide and different classes of organic peroxides. Low water oxygen and high temperature levels in the Bgd locality suggesting different metabolic activity between examined locations. Our results suggest that different presence and concentrations of individual environmental factors (total environment) influence the way how fish establish homeostasis.

Effect of nutritive status on Mytilus galloprovincialis pollution biomarkers: Implications for large-scale monitoring programs

Biomarkers have been extensively used in monitoring programs with the aim of assessing the biological effects of pollutants on marine organisms and determining environmental status. Data obtained from these programs are sometimes difficult to interpret due to the large amount of natural variables affecting biological processes, which could act as confounding factors on biomarker responses. The main aim of this work was to identify the effect of one of these variables, the food availability, and consequently, the mussel nutritive status, on biomarker responses. For that purpose, mussels (Mytilus galloprovincialis) were conditioned to three different food rations for 2 months in order to create three mussel nutritive statuses and afterwards, each status was exposed to three nominal concentrations of fluoranthene (FLU) for 3 weeks. A battery of biomarkers was considered in this study to cover a wide range of organism responses, both physiological (scope for growth - SFG) and biochemical (superoxide dismutase - SOD, catalase - CAT, glutathione reductase - GR, glutathione peroxidase - GPx, glutathione-S-transferase - GST and phenoloxidase - PO activities, and lipid membrane peroxidation - LPO). The results obtained, evidenced that most of the studied biomarkers (SFG, SOD, CAT, GPx, and PO) were strongly affected by mussel nutritive status, showing higher values at lower status, whereas the effect of toxicant was not always evident, masked by the nutritive status effect. This paper demonstrates that toxicants are not the only source of variability modulating pollution biomarkers, and confirms nutritive status as a major factor altering biochemical and physiological biomarkers.

Proteomic profiling of white muscle from freshwater catfish Rita rita

Muscle tissues contribute 34-48 % of the total body mass in fish. Proteomic analysis enables better understanding of the skeletal muscle physiology and metabolism. A proteome map reflects the general fingerprinting of the fish species and has the potential to identify novel proteins which could serve as biomarkers for many aspects of aquaculture including fish physiology and growth, flesh quality, food safety and aquatic environmental monitoring. The freshwater catfish Rita rita of the family Bagridae inhabiting the tropical rivers and estuaries is an important food fish with high nutritive value and is also considered a species of choice in riverine pollution monitoring. Omics information that could enhance utility of this species in molecular research is meager. Therefore, in the present study, proteomic analysis of Rita rita muscle has been carried out and functional genomics data have been generated. A reference muscle proteome has been developed, and 23 protein spots, representing 18 proteins, have been identified by MALDI-TOF/TOF-MS and LC-MS/MS. Besides, transcript information on a battery of heat shock proteins (Hsps) has been generated. The functional genomics information generated could act as the baseline data for further molecular research on this species.

Induction of brown cells in Venerupis philippinarum exposed to benzo(a)pyrene

Benzo(a)pyrene is an important polycyclic aromatic hydrocarbon (PAH) commonly present in the marine environment and responsible for carcinogenic, teratogenic and mutagenic effects in various animal species. In the present study, we investigated by both histochemical and immunohistochemical approaches the effect of an acute exposure to different concentrations of B(a)P in the Manila clam Venerupis philippinarum. The general morphology of the different clam tissues, which was investigated histologically, evidenced a significant increase in the number of intestinal brown cells after B(a)P exposure. An increasing trend response to B(a)P was detected. The histochemical analysis for lipofuscin revealed the presence of lipofuscin-like substances inside the cytoplasm of intestinal brown cells. The same cells exhibited a PAS positivity and a reactivity to Schmorl's solution for melanin pigment. Moreover, intestinal brown cells exhibited an immunopositivity to HSP70 antibody confirming the increasing trend response to B(a)P detected by the histochemical analysis. Our results suggest that histological tissue changes resulting from exposure to B(a)P can be an useful marker in biomonitoring studies.

Synergistic effects of toxic elements on heat shock proteins

Heat shock proteins show remarkable variations in their expression levels under a variety of toxic conditions. A research span expanded over five decades has revealed their molecular characterization, gene regulation, expression patterns, vast similarity in diverse groups, and broad range of functional capabilities. Their functions include protection and tolerance against cytotoxic conditions through their molecular chaperoning activity, maintaining cytoskeleton stability, and assisting in cell signaling. However, their role as biomarkers for monitoring the environmental risk assessment is controversial due to a number of conflicting, validating, and nonvalidating reports. The current knowledge regarding the interpretation of HSPs expression levels has been discussed in the present review. The candidature of heat shock proteins as biomarkers of toxicity is thus far unreliable due to synergistic effects of toxicants and other environmental factors. The adoption of heat shock proteins as "suit of biomarkers in a set of organisms" requires further investigation.

Biochemical markers of pollutant responses in macrozoobenthos from the White Sea: intracellular proteolysis

Coastal environments of Kandalaksha Gulf in the White Sea (Russia) despite nature conservation efforts are heavily influenced by human activities. Biological effects of complex environmental pollution, including organic substances, heavy metals, and oil hydrocarbons, were assessed in widely distributed marine invertebrates, Gammarus duebeni (Crustacea, Amphipoda) and Mytilus edulis (Mollusca, Bivalvia), collected from a series of anthropogenically-impacted areas and distanced reference sites in Kandalaksha Gulf. The parameters of intracellular protein degradation pathways such as cytosol calpain system and lysosomal cathepsins B (CatB) and cathepsin D (CatD) were studied. The response reactions observed in invertebrates vary in specificity and ranged from adaptive to destructive depending on the total contaminant level and the nature of predominant pollutant. The ecological relevance of studied parameters as biomarkers was confirmed by their ability to indicate both expose to pollutants and adverse effects at the organism level.

Identification of a CYP3A-like gene and CYPs mRNA expression modulation following exposure to benzo[a]pyrene in the bivalve mollusk Chlamys farreri

In this study, we isolated a CYP3A-like gene from ovary of the scallop (Chlamys farreri). High levels of CYP3A-like gene expression occur in the digestive gland and gonad, which suggested their role in the metabolism of steroids and xenobiotics. Scallops were exposed to a polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene (B[a]P) for 10 days. The CYP4 and CYP3A-like gene can be up-regulated by B[a]P in a dose-dependent manner after 10 days exposure. But no induction of the CYP3A-like was observed in 10 μg/L B[a]P group. The CYP1A-like expression can only be induced by 0.025 μg/L B[a]P. 0.5 and 10 μg/L B[a]P caused significant DNA damage and 10 μg/L B[a]P can also lead to oxidative damage. These results demonstrate that the mollusk CYPs can be modulated by environmental pollutant, and the blocked induction of CYP3A-like and CYP1A-like expression probably results from the high genotoxicity and oxidative damage partly.

Integrated use of antioxidant enzymes and oxidative damage in two fish species to assess pollution in man-made hydroelectric reservoirs

This study investigated the relationship between contaminant body burden and the oxidative stress status of the gills and livers of two wild fish species in the Furnas Hydroelectric Power Station (HPS) reservoir (Minas Gerais, Brazil). Gills and livers presented similar pathways of metals and organochlorine bioaccumulation. During June, organochlorines were associated with lipid peroxidation (LPO), indicating oxidative stress due to the inhibition of the antioxidant enzymes superoxide dismutase and glutathione peroxidase. In the most polluted areas, metal concentrations in the liver were associated with metallothionein. During December, contaminants in the gills and liver were associated with catalase activity and LPO. Aldrin/dieldrin was the contaminant most associated with oxidative damage in the livers of both species. This integrated approach shed light on the relationship between adverse biological effects and bioaccumulation of contaminants inputted by intensive agricultural practices and proved to be a suitable tool for assessing the environmental quality of man-made reservoirs.

Identification and expression of multiple CYP1-like and CYP3-like genes in the bivalve mollusk Mytilus edulis

Various sequencing projects over the last several years have aided the discovery of previously uncharacterized invertebrate sequences, including new cytochrome P450 genes (CYPs). Here we present data on the identification and characterization of two CYP1-like and three CYP3-like genes from the bivalve mollusk Mytilus edulis, and assess their potential as biomarkers based on their responses to several known vertebrate aryl hydrocarbon receptor (AHR) agonists. Quantitative real-time PCR was used to measure CYP transcript levels in digestive gland, labial palps, adductor muscle, gill, foot, and different regions of the mantle. Levels of both CYP1-like genes were highest in digestive gland, whereas labial palps had the highest expression levels of the three CYP3-like genes followed by digestive gland and outer margin of the mantle. Mussels were exposed by injection to the AHR agonists, β-naphthoflavone (BNF; 25 μg g(-1)), 3,3',4,4',5-polychlorinated biphenyl (PCB126; 2 μg g(-1)), or 6-formylindolo[3,2-b]carbazole (FICZ; 0.1 μg g(-1)), or to Aroclor 1254 (a mixture of PCBs; 50 μg g(-1)) for 24 h, followed by CYP expression analysis. There was no statistically significant change in expression of either of the CYP1-like genes after exposure to the various AHR agonists. The CYP3-like-1 gene was significantly up-regulated by BNF in gill tissues and the CYP3-like-2 gene was up-regulated in digestive gland by PCB126 and in gill tissue by BNF. These results suggest that distinct mechanisms of CYP gene activation could be present in M. edulis, although the importance of the CYP1-like and CYP3-like genes for xenobiotic and endogenous lipids biotransformation requires additional investigation.

Ecotoxicological heterogeneity in transitional coastal habitats assessed through the integration of biomarkers and sediment-contamination profiles: a case study using a commercial clam

Transitional waterbodies, such as estuaries, are highly diversified environments with respect to ecology, geophysics, and nature of anthropogenic impacts. This spatial heterogeneity may pose important constraints when developing monitoring programmes for aquatic pollution. The present study compared three distinct coastal ecosystems located in Southern Portugal (subjected to different anthropogenic stressors), namely, two estuaries and a coastal lagoon, through the characterisation of sediment contamination and a biomarker approach to an important commercial clam (Ruditapes decussatus) obtained from local fishing grounds. The results showed high heterogeneity of sediment contamination for both estuaries and a marked distinction between industrially and agriculturally influenced areas as well as between natural and artificialized sites. Hydrodynamics and oceanic influence (in essence dictating sediment type) play a major role in environmental quality. Environmental heterogeneity constituted an important confounding factor for biomarker analysis in the clams' digestive glands since the animals appeared to respond to their immediate surroundings' characteristics rather than the geographical area where they were collected from, despite the relative distance to pollution hot spots. Still, oxidative stress biomarkers (lipid peroxidation and catalase activity) could correlate with each other and to both organic and metallic contamination, whereas metallothionein-like protein induction failed to correlate to any class of sediment toxicants (albeit metals being the most representative pollutants) and appeared to be strongly affected (unlike the previous) by clam size and probably other unknown internal and external variables, among which contaminant interactions should play a major role.

Phase I and II biotransformation enzymes and polycyclic aromatic hydrocarbons in the Mediterranean mussel (Mytilus galloprovincialis, Lamarck, 1819) collected in front of an oil refinery

The aim of the present study was to investigate the responses of phase I and II biotransformation enzymes and levels of PAHs in the Mediterranean mussel (Mytilus galloprovincialis, Lamarck, 1819) collected from three sites at different distance from an oil refinery. Phase I enzyme activities as NAD(P)H-cyt c red, NADH ferry red, B(a)PMO and phase II as UDPGT, GST were measured in digestive gland while 16 PAHs (US-EPA) in whole soft tissue. An added value to the data obtained in the present study rely on the RDA analysis which showed close correlations between PAHs levels and phase I enzyme activities in mussels collected in front of the refinery. And again a significant spatial correlation between B(a)P levels and NADPH-cyt c red activities was observed using linear models. No differences among sites for B(a)PMO and phase II GST activities were observed, while the application of UDPGT as biomarkers requires further investigation.

Assessment of the mechanisms of detoxification of chemical compounds and antioxidant enzymes in the digestive gland of mussels, Mytilus galloprovincialis, from Mediterranean coastal sites

In this study the effects of the main marine pollutants (metals, PAHs, PCBs and DDTs) were assessed in native mussels from the Mediterranean coast of Spain. For this purpose several biomarkers such as benzo[a]pyrene hydroxylase (BPH), DT-diaphorase (DTD), glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPs), glutathione reductase (GR), metallothionein (MT) and lipid peroxidation (LPO) were measured in the digestive gland. Results showed increased LPO levels in mussels which accumulated high loads of organic compounds and arsenic in their tissues. BPH levels correlated to the concentrations of organic compounds in mussel tissues, though the range of BPH response was low in relation to the high gradient of accumulation of organic pollutants. Increased BPH levels, concomitant to low DTD and GST activities, were detected in mussels which presented high levels of organic pollutants in their tissues. This suggests that signs of LPO present in these organisms are related to the imbalance between phase I and phase II biotransformation processes. Furthermore, the increased levels of MT and CAT detected in mussels which showed high levels of Cd in their tissues appear to reflect a coordinated response which protects against the toxicity of this metal. The application of these biomarkers in environmental assessment is discussed.

Responses of CYP450 dependent system to aliphatic and aromatic hydrocarbons body burden in transplanted mussels from South coast of Portugal

Mussels Mytilus galloprovincialis were cross-transplanted at South Portugal from a reference site (site 1) to a site more contaminated with hydrocarbon compounds (site 2), and vice versa, in an active biomonitoring (ABM) concept, to assess the biotransformation capacity catalyzed by the mixed function oxygenase (MFO) system. Total alkanes (TAlk), the unresolved complex mixture (UCM), and total polycyclic aromatic hydrocarbons (TPAHs) concentration increased respectively 6, 4.4 and 4.2 fold relatively to control, in mussels transplanted from site 1 to 2. In the cross-transplant, a 48, 57 and 62% depuration of TAlk, UCM and TPAHs concentrations occurred by the end of the 3-4th week. Petrogenic and biogenic (marine and terrigenous) sources of AHs, and petrogenic and pyrolitic (biomass and oil/fuel incomplete combustion) sources of PAHs were detected at both sites. CYP450, CYT b (5) and NADPH-RED in mussels transplanted from site 1 to 2 were induced from day 0 to 28, with a total increase of 35, 32 and 35%, respectively, while biochemical equilibrium to lesser environmental contamination occurs in mussels transplanted from site 2 to 1. A significant relationship between CYP450 and NADPH-RED was found with TPAH, with distinctive behavior at the two sites. MFO system components increase with exposure time at one site and decreases in the other, reflecting an adaptation to distinct environmental hydrocarbon loads. The ABM strategy proved to be useful to understand the environment real impact on the biochemical responses in mussels' local populations. In this study, CYP450 and NADPH-RED are a useful biomarker for hydrocarbon exposure.

Molecular and biochemical biomarkers responses in the mussel Mytilus edulis collected from Southern Brazil coast

Marine ecosystems are typically subjected to a variety of stressors containing complex xenobiotics mixtures. This study aims to evaluate the responses of molecular and biochemical biomarkers in the mussel Mytilus edulis providing data for environmental monitoring programs development in Southern Brazil. Mussels were collected at a polluted site, near Patos Lagoon outfall, and at a control site. Gills, muscle and mantle samples were used for biomarker determinations. Mussels collected at the polluted site significantly increased superoxide dismutase (SOD) and glutathione S-transferase (GST) activities and decreased catalase (CAT) activity. Moreover, an increase in sod1, gstπ and hsp70 mRNA expression was observed. Overall, biochemical and molecular biomarkers responses were observed, but these responses varied depending on the analyzed tissue. These results indicate possible contaminants effects on organisms and the need for effective environmental monitoring programs in this ecosystem.

Biomarker responses and genotoxicity in the mud snail (Bullacta exarata) as indicators of coastal contamination

In the present study different biomarker responses and genotoxicity were determined in wild mud snails (Bullacta exarata) collected from 3 sampling sites in Bohai Bay in northeastern China, which is a region that is under considerable anthropogenic influence. Significant spatial variability of superoxide dismutase (SOD) and metallothionein (MT)-like proteins were recorded, while glutathione transferase (GST), catalase (CAT), and vitellin-like proteins (Vn's) were not observed. Furthermore, genomic DNA that was amplified with 4 fluorescence-labeled primer pairs showed variable genetic distances among the 3 wild mud snail populations found in Bohai Bay, which may be correlated with differences in the types of environmental genotoxicants, such as heavy metals and polycyclic aromatic hydrocarbons. This multi-biomarker approach provided an improved understanding of the potential toxicological impact of contaminated sediments on benthic organisms.

Antioxidant responses and bioaccumulation in green-lipped mussels (Perna viridis) under acute tributyltin chloride exposure

Green-lipped mussels (Perna viridis) were exposed to waterborne tributyltin chloride (TBTCl) at different concentrations (0.2, 0.4 and 0.8 μg L(-1)) for up to 72 h. Accumulated TBTCl in Perna viridis correlated linearly with the exposure concentrations of 0.2 μg L(-1)(R(2) = 0.772), 0.4 μg L(-1)(R(2) = 0.952), and 0.8 μg L(-1)(R(2) = 0.909). The results of superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA) all decreased in gill tissues after 24 h of exposure, but the hepatic SOD and the hepatic GPx showed either little or no effect on exposure of TBTCl solutions. Analysis using the Spearman rank correlation coefficient showed the hepatic GPx activity appeared to have a significant negative correlativity (R(s) = -0.42) with the exposed TBTCl concentrations, and the hepatic MDA was significantly negatively correlated (R(s) = -0.33) with the tissue TBTCl concentrations. Conversely, a significant positive correlation (R(s) = 0.60) was shown between the gill MDA contents and exposure time. This study illustrates oxyradical scavenger GPx best correlated with stress level of pollutants among the various antioxidant parameters.

A multi-biomarker approach in cross-transplanted mussels Mytilus galloprovincialis

The present work integrates the active biomonitoring (ABM) concept in mussels Mytilus galloprovincialis from the South coast of Portugal transplanted during 28 days between two sites with different sources of contamination, and vice versa, in order to assess biological effects in these mussels. For that purpose a multibiomarker approach was used. The suit of biomarkers indicative of metal contamination were metallothioneins (MT) and the enzyme δ-aminolevulinic acid dehydratase (ALAD), for organic contamination mixed function oxidase system (MFO), glutathione-S-transferase (GST) and acetylcholinesterase (AChE), as oxidative stress biomarkers superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and lipid peroxidation (LPO). These biomarkers were used to determine an index to evaluate the stress levels in these two sites. Site A is strongly influenced by metallic contamination, with higher Cu, Cr and Pb in M. galloprovincialis, as well as higher MT levels, antioxidant enzymes activities and LPO concentrations, and lower ALAD activity. In site B organic compounds (PAHs) are prevalent and native mussels show higher activities of the MFO system components and GST. Transplanted mussels had significant alterations in some biomarkers that reflect the type of contaminants present in each site, which demonstrates the primary role of the environment in determining the physiological characteristics of resident mussels. Therefore the application of ABM using a battery of biomarkers turns out to be a useful approach in sites where usually complex mixtures of contaminants occurs. In this study the biomarkers that better differentiate the impact of different contaminants at each site were MT, CYP450, SOD and CAT.

Comparative study of the accumulation and detoxification of Cu (essential metal) and Hg (nonessential metal) in the digestive gland and gills of mussels Mytilus galloprovincialis, using analytical and histochemical techniques

The aim of the present study is the comparative examination of accumulation and detoxification of Cu and Hg in digestive gland and gills of mussels Mytilus galloprovincialis, using atomic absorption spectrophotometry and autometallography. Mussels were exposed to 0.08 mg L(-1) Cu, 0.08 mg L(-1) Hg, as well as to a mixture of 0.08 mg L(-1) Hg and 0.08 mg L(-1) Cu for 11 d. After the experimental exposure, animals were kept under laboratory conditions for a detoxification period of 7d. An antagonistic effect of Cu against to Hg accumulation was noted in the digestive gland of mussels after the experimental exposure, as well as after the detoxification period, supporting the protective role of Cu against to Hg toxicity in this tissue. Digestive gland was suggested as a main organ for Hg accumulation and gills as a target position for Cu accumulation. Additionally, lower time was evaluated for Hg detoxification in the digestive gland and gills of mussels, in relation to those addressed for Cu detoxification in the same tissues. The evaluation of black silver deposits (BSD) extent performed in digestive gland and gills was suggested as a less sensitive approach, in relation to atomic absorption spectrophotometry (AAS), to identify the concentration of heavy metals in tissues of mussels. The toxic effects of Hg, Cu and a mixture of them on lysosomal system of the digestive cells are also discussed.

Water column monitoring of the biological effects of produced water from the Ekofisk offshore oil installation from 2006 to 2009

The Norwegian water column monitoring program investigates the biological effects of offshore oil and gas activities in Norwegian waters. In three separate surveys in 2006, 2008, and 2009, bioaccumulation and biomarker responses were measured in mussels (Mytilus edulis) and Atlantic cod (Gadus morhua) held in cages at known distances from the produced water (PW) discharge at the Ekofisk oil field. Identical monitoring studies performed in all three years have allowed the biological effects and bioaccumulation data to be compared, and in addition, enabled the potential environmental benefits of a PW treatment system (CTour), implemented in 2008, to be evaluated. The results of the 2009 survey showed that caged animals were exposed to low levels of PW components, with highest tissue concentrations in mussels located closest to the PW discharge. Mussels located approximately 1-2 km away demonstrated only background concentrations of target compounds. Concentrations of polycyclic aromatic hydrocarbons (PAH) and alkyl phenol (AP) metabolites in the bile of caged cod were elevated at stations 200-250 m from the discharge. There was also a signal of exposure relative to discharge for the biomarkers CYP1A in fish and micronuclei in mussels. All other fish and mussel biomarkers showed no significant exposure effects in 2009. The mussel bioaccumulation data in 2009 indicated a lower exposure to the PW effluent than seen previously in 2008 and 2006, resulting in an associated general improvement in the health of the caged mussels. This was due to the reduction in overall discharge of PW components (measured as oil in water) into the area in 2009 compared to previous years as a result of the improved PW treatment system.

Metallothionein in the freshwater gastropod Melanopsis dufouri chronically exposed to cadmium: a methodological approach

Previous studies have demonstrated that the use of differential pulse polarography (DPP) for metallothionein (MT) determination in marine gastropod tissues, particularly the digestive gland, requires taking into account the presence of heat-stable high molecular weight compounds that exhibit polarographic signal. In the present paper, similar compounds were identified in tissues from the freshwater snail Melanopsis dufouri which also interfere with MT determination by DPP and, due to their silver binding capacity, also interfere in the silver assay for MT quantification. Ultrafiltration seems to be effective in removing these high molecular weight compounds from heat-denatured homogenate supernatant allowing direct MT quantification by DPP. A fully validated procedure for metallothionein determination in M. dufouri is described. In spite of a considerable accumulation of cadmium in the visceral complex of M. dufouri following exposure to 100 microg CdL(-1) for 8 weeks (up to 37 microgg(-1)) only a small increase in MT concentration was found.

Integrated assessment of water quality of the Costa da Morte (Galicia, NW Spain) by means of mussel chemical, biochemical and physiological parameters

The aim of this study was to assess environmental quality at some of the sites most severely affected by the Prestige oil spill off 2 years after the spillage (April and November 2004). For this purpose analyses of polycyclic aromatic hydrocarbons (PAH) and several biochemical (antioxidant enzymes catalase, glutathione reductase, glutathione peroxidase, superoxide dismutase and DT-diaphorase and lipid peroxidation) and physiological [scope for growth (SFG)] biomarkers were determined on wild mussel populations (Mytilus galloprovincialis) collected at four points along the Costa da Morte and compared with those of a reference site not affected by the oil spill. Results showed that PAH contents had markedly decreased 17 months after the accident, although they were higher in April than in November, when they showed values similar to background levels reported for this area. Nevertheless, the predominance of chrysene on PAH profiles, similarly to findings obtained immediately after the spill, indicated the Prestige as their main source. In spite of the low PAH levels recorded, antioxidant activity levels (explained through the integrated antioxidant response-IAR) were higher in the Costa da Morte than at the reference site either in April and November. In April IAR seems to be related to PAH levels found 3 months after the accident (February 2003), suggesting the persistence in the environment of oxidative stress-producing components from the spill. However, evidence of oxidative stress was not reflected at physiological level by scope for growth, with only very slight differences being observed between values from the reference site and those from Costa da Morte sites. In conclusion, although 2 years after the spill PAHs bioaccumulated by mussels from the Costa da Morte had decreased to background levels, biochemical parameters showed signals of oxidative stress in mussels from this area. However, SFG reflected a good health status for the mussel populations studied and did not reveal evidence of physiological disturbance either 17 or 24 months after the Prestige spill.

Polycyclic aromatic hydrocarbons concentrations and biomarker responses in the clam Ruditapes decussatus transplanted in the Ria Formosa lagoon

Clams Ruditapes decussatus were transplanted in the Ria Formosa lagoon and the variation of PAH concentrations in the whole soft tissues measured, along with a suite of biomarkers, including the following: (a) phase I and phase II metabolism of xenobiotics enzymes: benzo[a]pyrene hydroxylase (BPH) and glutathione S-transferase (GST); (b) antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidases and (c) lipid peroxidation (LPO) levels. Individual PAHs were differently accumulated and eliminated by R. decussatus. During the metabolisation of PAHs by R. decussatus BPH was clearly induced in the digestive gland. Moreover, ROS lead to the induction of protective antioxidant enzymes still causing oxidative damage to membranes. Therefore, BPH seems to be a relevant indicator of PAHs in R. decussatus.

Multi-biomarker responses in the freshwater mussel Dreissena polymorpha exposed to polychlorobiphenyls and metals

Contaminant related changes in behavioral, phase I and II metabolizing enzymes and pro-oxidant/antioxidant processes in the freshwater mussels Dreissena polymorpha exposed to metals and PCBs were assessed. Behavioral and biochemical responses including filtering rates, key phase I, II and antioxidant enzymes and levels of metallothioneins, glutathione, lipid peroxidation and DNA strand breaks were determined in digestive glands of mussels after being exposed to sublethal levels of mercury chloride, methyl mercury, cadmium and Aroclor 1260 during 5 days. In 7 out of 12 responses analyzed, mussels showed significant differences across treatments. Unusual properties of measured ethoxyresorufin-O-deethylase (EROD) activities indicated that mussels lack an inducible CYP1A enzymatic activity. Despite of using similar exposure levels, inorganic and organic mercury showed different biomarker patterns of response with methyl mercury being more bio-available and unable to induce metallothionein proteins. Mussels exposed to Cd presented higher levels of metallothioneins and an enhanced metabolism of glutathione, whereas those exposed to Aroclor showed their antioxidant glutathione peroxidase related enzyme activities inhibited. Although there was evidence for increased lipid peroxidation under exposure to inorganic and organic mercury, only mussels exposed to Aroclor had significant greater levels than those in controls.

MytiBase: a knowledgebase of mussel (M. galloprovincialis) transcribed sequences

BACKGROUND

Although bivalves are among the most studied marine organisms due to their ecological role, economic importance and use in pollution biomonitoring, very little information is available on the genome sequences of mussels. This study reports the functional analysis of a large-scale Expressed Sequence Tag (EST) sequencing from different tissues of Mytilus galloprovincialis (the Mediterranean mussel) challenged with toxic pollutants, temperature and potentially pathogenic bacteria.

RESULTS

We have constructed and sequenced seventeen cDNA libraries from different Mediterranean mussel tissues: gills, digestive gland, foot, anterior and posterior adductor muscle, mantle and haemocytes. A total of 24,939 clones were sequenced from these libraries generating 18,788 high-quality ESTs which were assembled into 2,446 overlapping clusters and 4,666 singletons resulting in a total of 7,112 non-redundant sequences. In particular, a high-quality normalized cDNA library (Nor01) was constructed as determined by the high rate of gene discovery (65.6%). Bioinformatic screening of the non-redundant M. galloprovincialis sequences identified 159 microsatellite-containing ESTs. Clusters, consensuses, related similarities and gene ontology searches have been organized in a dedicated, searchable database http://mussel.cribi.unipd.it.

CONCLUSION

We defined the first species-specific catalogue of M. galloprovincialis ESTs including 7,112 unique transcribed sequences. Putative microsatellite markers were identified. This annotated catalogue represents a valuable platform for expression studies, marker validation and genetic linkage analysis for investigations in the biology of Mediterranean mussels.

Biomarker responses in mussels, an integrated approach to biological effects measurements

Biological effects techniques have been used with the aim to further integrate biological effects measurements with chemical analysis and apply these methods to provide an assessment of mussel health status. Live native mussels were collected from selected coastal and estuarine sites around the British Isles, including the rivers Test, Thames, Tees, and Clyde, and Lunderston Bay. A suite of biological effects techniques was undertaken on these mussels, including whole organism responses (scope for growth), tissue responses (histopathology), and subcellular responses (lysosomal stability, multi-xenobiotic resistance [MXR], and Comet assay). In addition, whole mussel homogenates were used to measure organic (polycyclic aromatic hydrocarbons [PAH], polychlorinated biphenyls [PCB]) and metal concentrations. Overall the mussels collected from the Thames were in relatively poor health, based on histopathological markers, significantly higher DNA damage, and elevated expression of MXR detoxifying proteins. In contrast, the mussels collected from the River Test were in the best health, based on histopathological markers, respiration rate (SFG), and low frequency of DNA damage. In conclusion, the biological effects techniques were able to distinguish between relatively contaminated and clean environments, with the Thames mussels in worst health. Mussel tissue chemistry data were not able to explain the variations in biological response. Evidence indicates that the difference in the health of the mussels between the different sites was due to either effects of contaminants that were not measured, or the combined effects of mixture toxicity resulting in a threshold effect.

Evaluation of pollutant exposure by chemical and biological markers in a Mediterranean French urban stream: a step for in situ calibration of multixenobiotic resistance transporter expression as biomarker in Chironomidae larvae

This study was aimed at semi-quantifying the membrane density of multixenobiotic resistance (MXR) transporters in Chironomidae Orthocladiinae larvae from an urban stream by ELISA assay. The relationships between the MXR transporter membrane density and limnological parameters and pollutant concentrations, 16 priority polycyclic aromatic hydrocarbons (PAHs), as per the US Environmental Protection Agency (EPA) and seven polychlorobiphenyl congeners (PCBs), were assessed. Midge larvae were collected, and limnological parameters and pollutant concentrations were measured in three sites of a French Mediterranean urban stream, two located after sewage treatment plants, and one closed to the river mouth, and in two additional sites, one on the stream tributary, and one in a non-urbanized stream located in the same region. Results show that the PAH and PCB contamination levels are different between sites and that some congener concentrations are above their threshold toxic effect level (TEL). The MXR transporter membrane density was significantly higher in larvae from the tributary, the most polluted site, as compared with larvae from the non-urbanized stream. The MXR transporter density was positively correlated with 10 of the 16 US-EPA PAH concentrations and the increase in the MXR transporter density seems to be due to the US-EPA PAH concentrations that were above their TEL. No relations with PCB concentrations or limnological parameters were found. The results suggest that the MXR transporter membrane density in Chironomidae larvae could be an interesting biological marker of PAH exposure in freshwater ecosystems.

Antioxidant responses to polycyclic aromatic hydrocarbons and organochlorine pesticides in green-lipped mussels (Perna viridis): do mussels "integrate" biomarker responses?

Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCs) are generally present in the marine environment in complex mixtures. The ecotoxicological nature of contaminant interactions, however, is poorly understood, with most scientific observations derived from single contaminant exposure experiments. The objective of this experiment was to examine dose-response relationships between antioxidant parameters and body contaminant levels in mussels exposed to different exposure regimes under laboratory conditions. Accordingly, the green-lipped mussel, Perna viridis, was challenged with a mixture of PAHs (anthracene, fluoranthene, pyrene, benzo[a]pyrene) and OC pesticides (alpha-HCH, aldrin, dieldrin, p,p'-DDT) over a 4 week period. Contaminants were delivered under four different dosing regimes, with all treatments receiving the same total contaminant load by the end of the exposure period. Antioxidant biomarkers were measured after 1, 2, 3 and 4 weeks, including glutathione (GSH), gluathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and lipid peroxidase (LPO). GST and CAT were induced in hepatic tissues in most of the exposure regimes, with the majority of significant induction occurring in a constant exposure regime and a two-step alternate exposure regime. Significant differences among exposure regimes were detected in the body burden of contaminants after 28 days. Hepatic CAT and GSH are proposed as potentially useful biomarkers as they showed good correlation with target contaminants and were not readily affected by different dosing patterns.

Comparative petroleum hydrocarbons levels and biochemical responses in mussels from hydrothermal vents (Bathymodiolus azoricus) and coastal environments (Mytilus galloprovincialis)

Aliphatic hydrocarbons and PAHs in the whole soft tissues of Bathymodiolus azoricus from three Mid-Atlantic Ridge hydrothermal vents (Menez-Gwen, Lucky Strike and Rainbow), and Mytilus galloprovincialis from three contaminated coastal sites in South Portugal were analysed, and its effects on the digestive gland microsomes mixed-function oxygenase system (MFO) were assessed. Aliphatic hydrocarbons levels were present in the same magnitude in both coastal and hydrothermal environments, while the UCM (unresolved complex mixture) for coastal mussels were higher than in vent mussels. In general, significantly higher PAHs concentrations were found in coastal mussels, compared to B. azoricus where low molecular weight PAHs (2-3 rings) represented the majority of PAHs contrarily to what was observed in M. galloprovincialis. The MFO components were present in both mussel species, and were detected in vent mussels for the first time. However this system seems to have different roles in species from these contrasting environments. In coastal mussels MFO responded to hydrocarbon contamination while response in hydrothermal organisms appeared to be related mainly to endogenous factors.

Proteomics-based method for risk assessment of peroxisome proliferating pollutants in the marine environment

Pollution in aquatic environment is of increasing concern for its impact on both human and natural populations. Applying proteomics to monitor marine pollution is a new approach to evaluate the effects of environmental pollutants on the biota. Aquatic organisms living in coastal and estuarine areas are particularly prone to exposures to a variety of pollutants, some of which can act as peroxisome proliferators. However, peroxisomal responses in particular and biomarker responses in general can be influenced by several biotic and abiotic factors. Utilizing proteomics-based techniques that permit the evaluation of hundreds to thousands of proteins in a single experiment can circumvent those drawbacks. Applying this method, the peroxisomal proteome from digestive glands of mussels Mytilus sp. can be analyzed by two-dimensional electrophoresis (2-DE) and the 2-DE maps from control samples and samples obtained in a polluted area can be compared. The up- and down-regulated proteins compose the protein expression signature (PES) associated with exposure to peroxisome proliferating pollutants. This method generates highly reproducible patterns that can be applied to laboratory or field experiments.

DNA adducts and polycyclic aromatic hydrocarbon (PAH) tissue levels in blue mussels (Mytilus spp.) from Nordic coastal sites

DNA adducts in gills and digestive gland, as well as polycyclic aromatic hydrocarbon (PAH) tissue levels were analysed in blue mussels (Mytilus spp.) from Nordic coastal areas (Iceland, Norway and Sweden) with diffuse or point sources of PAHs of various origins. Both DNA adduct and PAH tissue levels were generally low, indicating low PAH exposure to the mussels in the areas studied. DNA adducts were found to be higher in gills than in digestive gland of the mussels at all sites studied. Elevated DNA adduct levels in gills were found at 6 sites out of 18 compared to reference sites in respective coastal zones. Adduct levels ranged from 0.5 to 10 nmol adducts/mol normal nucleotides, being highest in mussels from Reykjavík harbour, Iceland (intertidal mussels), and from Fiskaatangen, Norway (subtidal mussels). Total PAH tissue levels in the mussels ranged between 40 and 11,670 ng/g dry wt., and were significantly correlated with DNA adduct levels (r(2)=0.73, p<0.001). PAH ratio values indicated that the PAHs were in most cases of pyrolytic origin, but with petrogenic input near harbours and an oil refinery.

Comparison of key enzymes in the zebra mussel, Dreissena polymorpha, the earthworm Allolobophora chlorotica and Chironomus riparius larvae

The levels of the enzymes, glutathione S-transferase, catalase, NAD(P)H-cytochrome c reductases, and DT-diaphorase were determined and compared in the tissues of three invertebrates commonly used in monitoring environmental quality: a freshwater mussel, Dreissena polymorpha, the earthworm Allolobophora chlorotica and the fourth instar of Chironomus riparius. It was found that the activities of GST, catalase, and NAD(P)-cytochrome c reductases were comparable in A. chlorotica and C. riparius, whereas comparatively a higher GST and a lower catalase activity was determined in the mussel tissues. DT-diaphorase was not detectable in A. chlorotica and the C. riparius larvae tissues, whereas this enzyme is present in the gills and the rest of soft mussel tissues (soft mussel tissues minus gills). It is suggested that the relatively low catalase activity observed in the tissues of the latter organism might be compensated by the presence of the antixidant role of DT-diaphorase. In addition, the inducibility of DT-diaphorase in D. polymorpha, by butylated hydroxyanisole (BHA) and lead (Pb) was investigated. Despite the bioaccumulation of both BHA (5.2+/-0.14 microgg(-1) wet weight) and Pb (233.7+/-0.95 mgkg(-1) dry weight) in the soft mussel tissues, the mussel DT-diaphorase was not induced. Although the activity of NADPH-cytochrome c (P-450) reductase was also not affected by these reagents, its activity was 2-fold higher in the gills than the rest of soft mussel tissues.

Glutathione S-tranferases and cytochrome P450 activities in Mytilus galloprovincialis from the South coast of Portugal: effect of abiotic factors

To assess the health of aquatic organisms, biomarkers that measure changes at the biochemical level have been used as effective early warning tools in ecological risk assessment. In order to develop an integrated risk assessment strategy for the south coast of Portugal, mussels Mytilus galloprovincialis were collected from six sites along the coast with different organic contaminant characteristics. Additionally, an active biomonitoring approach was followed by transplanting indigenous mussels from site 4 to 6 and vice versa (from site 6 to 4) for 28 days. PAHs and PCBs contents were measured and the associated responses of phase I and phase II detoxification mechanisms evaluated by measuring cytochrome P450 and GST activities. GST activity was also determined on different tissues (gills, digestive gland, foot, mantle and gonads) of M. galloprovincialis and the impact of abiotic parameters (temperature, salinity, pH, conductivity and dissolved oxygen) on the GST activity assessed. Results indicate that CYP 450 follow the same pattern of PAHs and a direct relationship exist between CYP 450 and PAH levels from the different sites. Although there is a decrease between GST and PAHs concentrations it was not significant. The majority of the GST activity was in the gills and the digestive gland (around of 75% of the activity measured in all tissues) followed in decreasing order by the mantle, gonads. An inverse relationship between GST activity and salinity was detected along with temperature although not significant. These two biomarkers respond to changes of these two groups of compounds and to salinity especially for GST. In conclusion CYP 450 in mussels gives a reliable response as biomarker for organic contaminants in risk assessment in the South Coast of Portugal.

Effect of exposure to benzo[a]pyrene on SODs, CYP1A1/1A2- and CYP2E1 immunopositive proteins in the blood clam Scapharca inaequivalvis

The effects of water-borne exposure to benzo[a]pyrene (36 h; celite-bound 0.44 mg L(-1) B[a]P) on cytochrome P450 (CYP) and superoxide dismutases (SODs) were examined in digestive gland of the blood clam, Scapharca inaequivalvis. B[a]P accumulation and elimination were rapid, with maximum whole-body concentrations of 1.78 ng g(-1) wet wt after 12 h of treatment, followed by a progressive decline to 0.89 ng g(-1) at 36 h. The presence of B[a]P resulted in an increase in total CYP of digestive gland microsomes from 54+/-14 to 108+/-21 pmol/mg protein (mean+/-SD; p<0.05, 24 h). Increases were also seen in microsomal CYP1A1/1A2-immunopositive protein (50.5 kDa app. mol. wt; p<0.05), but not CYP2E1-immunopositive protein (49 kDa app. mol. wt.), indicating a specific response of the former isoform. Exposure to B[a]P produced a steady increase in Mn-SOD digestive gland activity (p<0.01; p<0.05) but no significant change in Cu/Zn-SOD activity. The respective proteins, measured by western blotting, were not significant induced after B[a]P exposure. Cu/Zn-SOD and Mn-SOD activities were correlated with total CYP levels (r=0.96 and 0.63, respectively), indicating a role for CYP in reactive oxygen species (ROS) production during exposure. Both 'NADPH-independent' and NADPH-dependent metabolism of B[a]P by digestive gland microsomes was seen, producing mainly 1,6-, 3,6- and 6,12-diones, with some phenols and 7,8-dihydrodiol; putative protein adducts were also formed. Redox cycling of the diones may also have contributed to ROS production, leading to the increased SOD activities.

Benzo[a]pyrene up-regulates the expression of the proliferating cell nuclear antigen (PCNA) and multixenobiotic resistance polyglycoprotein (P-gp) in Baltic Sea blue mussels (Mytilus edulis L.)

The expression of protein biomarkers in Baltic Sea blue mussels was analyzed after three days exposure to low (2.8 microg/animal/day), intermediate (28 microg/animal/day), or high (280 microg/animal/day) nominal doses of benzo[a]pyrene (BaP). Significant expression changes were found in the animals exposed to the low dose, the lowest reported dose for DNA adduct formation in the gills of Baltic Sea blue mussels. Up-regulated expression of the proliferating cell nuclear antigen (PCNA), quantified from Western blots, and no change in the 5-bromo-deoxyuridine (BrdU) staining pattern, determined by immunocytochemistry, indicated that the observed PCNA response was mainly non-proliferative, and thus possibly due to DNA damage. The expression of the multixenobiotic resistance polyglycoprotein (P-gp) was also up-regulated, proving its usefulness as an exposure marker to planar organic compounds. No effect of the BaP treatment with respect to the retinoblastoma 110 protein or heat shock proteins 60 and 70 was found. The variance in the medium and high dose data was too large to allow for the detection of significant expression changes. We suggest PCNA to be a marker for genotoxic stress derived from the polycyclic aromatic hydrocarbon BaP, irrespective of whether the stress leads to DNA repair or to cell proliferation.

Polycyclic aromatic hydrocarbons in food samples collected in Barcelona, Spain

This study reports on the concentrations of eight polycyclic aromatic hydrocarbons (PAHs) in food samples collected in the city of Barcelona (Catalonia, Spain) from 2003 to 2004. Food samples included meat products, fish (fresh and smoked), other seafood (cephalopods, crustaceans, and bivalves), vegetable oil, and tea. Concentrations of benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[g,h,i]perylene, benzo[alpha]pyrene, benzo[e]pyrene, dibenz[a,h]anthracene, and indeno[1,2,3-c,d]pyrene were determined by reversed-phase high-performance liquid chromatography with fluorescence detection. PAHs were detected in most tea samples (94%), which had the highest concentration of total PAHs (mean concentration of 59 microg/kg). Other food groups with a high presence of PAHs were bivalves (present in 34% of the samples; mean value of 2.7 microg/kg) and meat products (present in 13% of the samples; mean value of 1.7 microg/kg). The PAHs detected most frequently were benzo[e]pyrene and benzo[b]fluoranthene. No sample had levels above current regulation standards. Nevertheless, the frequent presence of PAHs in bivalves, tea samples, and meat products, together with the fact that dietary sources are the main exposure to these carcinogenic compounds, suggests the need for some monitoring scheme to follow up on these trends.

Application of SSH and a macroarray to investigate altered gene expression in Mytilus edulis in response to exposure to benzo[a]pyrene

The lack of genomic resources for aquatic invertebrates restricts their use as sentinel species in coastal environments. It is known that where genomic data are not available, suppression subtractive hybridisation (SSH) can generate cDNA libraries representative of pollutant-responsive gene transcription in aquatic vertebrates. To assess whether the approach was equally suited to aquatic invertebrates, altered gene expression in digestive gland of the mussel, Mytilus edulis, in response to exposure to benzo[a]pyrene (BaP) (1 mg/l) was investigated with SSH and a nylon macroarray. Screening of the subtracted libraries showed 112/250 up-regulated and 25/55 down-regulated clones were positive for differential expression and characterisation of these identified 87 with unique sequence suitable for array on a nylon membrane. The transcripts isolated were from a diverse range of genes involved in general stress, oxidative stress, cell adhesion, transcriptional and translational regulation, transport mechanisms, energy metabolism, cell metabolism, lipid metabolism, protein turnover and activation, lysosomal activity and 22 cryptic clones. Subsequent use of the clones in macroarray format to analyse expression of BaP-responsive genes (0 vs 4 day exposed) showed 0-100-fold increased levels of the forward-subtracted probes and between 0 and 0.1-fold down-regulation of the reverse-subtracted probes. Only 15% of the clones showed less than 2-fold change in expression. The gene ontology of the transcripts isolated demonstrates that BaP elicits a multitude of responses with a major feature being disruption of cellular redox status. The results indicate that the use of SSH and a macroarray is a robust method to discover novel pollutant-responsive genes in aquatic invertebrates.