Jean-François Narbonne

Polycyclic aromatic hydrocarbon (PAH) burden of mussels (Mytilus sp.) in different marine environments in relation with sediment PAH contamination, and bioavailability

Abstract Sediments and mussels (Mytilus edulis, Mytilus galloprovincialis) were sampled in different European coastal environments (Germany, France, Spain) and analysed for their polycyclic aromatic hydrocarbon (PAH) content by Gas Chromatography/Mass Spectrometry (GC-MS). Bioaccumulation factors of individual compounds from the sediment were calculated and discussed according to the compound solubility. The mussels showed different accumulation patterns according to the pollution source they were exposed to (dissolved fraction of PAHs, particulate fraction, petroleum present in the water column). The exposure source also depends on the geographical location of the mussels. In the Mediterranean Sea, the bivalves were mainly exposed to the dissolved fraction of PAHs, while in the Baltic Sea and in the Atlantic Ocean, the PAHs associated to the particles were significant sources.

URANIUM IN THE ENVIRONMENT: OCCURRENCE, TRANSFER AND BIOLOGICAL EFFECTS

The assessment of uranium chemical and radiological consequences depends on the physicochemical properties of these radioelements and the knowledge of their environmental fate. Although uranium is the source of all these fissionable isotopes, its fate in ecosystems has been poorly investigated. In this review, we have updated information concerning the fate of uranium in the different compartments of the environment, the possibility of transfer to man through the food chain, and the biological and toxicological effects of this metal at cellular, tissular, or organism levels. The physicochemical characteristics of uranium, as well as its regulatory statutes, were reviewed. The fate of uranium in the environment was presented by indicating sources of uranium emission and the possible routes of transfer to man. The biological alterations caused by uranium exposure were discussed, and finally, we presented results collected during our recent study. Some propositions on research to be done to advance the understanding of uranium occurrence in the environment were also given.

One-year monitoring survey of organic compounds (PAHs, PCBs, TBT), heavy metals and biomarkers in blue mussels from the Arcachon Bay, France

Marine mussels Mytilus sp. were transplanted on a monthly basis in cages over one year to oyster farms and harbours in the Arcachon Bay (France) in order to assess the water quality of the bay. Contaminant levels (organotin compounds, trace metals, PCBs and PAHs) were measured in tissues of transplanted mussels and mussels from a reference station, along with physiological parameters of the mussels (condition indexes, lipid content and dry weight). Four biomarkers (AChE: acetylcholinesterase activity, GST: gluthathione S-transferase activity, CAT: catalase activity and TBARS: thiobarbituric acid-reactive substance content) were also monitored. The remote stations monitored (oyster parks) exhibited no accumulation pattern of pollutants. Their respective concentrations therefore constitute a background level of the contamination in the bay ([TBT]= 30 ng Sn g(-1) dw, [SigmaHAPs]= 100 ng g(-1) dw, [SigmaPCBs]= 35 ng g(-1) dw). The elevated chemical contamination of the largest harbour of the bay, the Arcachon harbour, can be interpreted in terms of persistence of organotin compounds ([SigmaOTs]= 1500-2000 ng Sn g(-1) dw) and PAHs ([SigmaHAPs]= 4500-5000 ng g(-1) dw) in sediments and, to a lesser extent, of direct inputs of copper ([Cu]= 20 microg g(-1) dw in harbours versus 7 in oyster parks) and petrogenic PAHs ([methylphenanthrenes]= 1600 ng g(-1) dw in the dockyard versus 170 at the gas stations), related to the use of copper-based antifouling paints and to dockyard activity, respectively. However, the Arcachon Bay presents a low contamination level by PCBs and metals, including harbour stations. Furthermore, higher levels of other PAHs (particularly alkyl PAHs such as methylphenanthrenes/1600 ng g(-1) dw) not included in the 16 PAHs from the EPA priority list (usually studied in biomonitoring programmes/1500 ng g(-1) dw) in the Arcachon harbour underline the need to integrate these compounds in biomonitoring of highly PAH-polluted areas such as harbours in order to avoid misinterpretation of the biological responses observed. Biomarker responses were not able to discriminate the different chemical contamination levels recorded in the Arcachon Bay and rather reflected changes in environmental factors. Furthermore, the strong intraspecies variability of biological responses could be due to genetic differences of mussels from the Arcachon Bay. It is the first time that such an integrated monitoring is performed in the Arcachon Bay, also taking into account seasonal variations of chemical contents and biomarkers levels in mussel tissues.

Cholinesterases from the marine mussels Mytilus galloprovincialis Lmk. and M. edulis L. and from the freshwater bivalve Corbicula fluminea Müller

In order to improve the molecular basis for the use of bivalve cholinesterases as a reliable biomarker for aquatic pollution, the polymorphism and characterization of these enzymes in Mytilus edulis, Mytilus galloprovincialis and Corbicula fluminea were investigated. All results are consistent with the presence of only one pharmacological form of cholinesterase in each species. The molecular masses were 180 kDa for the two marine mussels and 240 kDa for C. fluminea. The cholinesterases are anchored to the membrane by a glycosyl inositol phosphate like the Ga form (type I) described in vertebrates. Surprisingly, these cholinesterases were poorly inhibited by organophosphorous compounds compared to enzymes from other sources. This suggests that these bivalves could be used as a biomarker for acute rather than chronic contaminations by anticholinesterase insecticides.

Effects of benzo(a)pyrene, 3,3′,4,4′-tetrachlorobiphenyl and 2,2′,4,4′,5,5′-hexachlorobiphenyl on the xenobiotic-metabolizing enzymes in the mussel (Mytilus galloprovincialis)

Benzo(a)pyrene (BaP), 3,3′,4,4′-tetrachlorobiphenyl (TCB) and 2,2′,4,4′,5,5′-hexachlorobiphenyl were tested for their ability to induce hepatic xenobiotic metabolizing enzymes in a marine mussel. TCB and BaP (two planar molecules), but not HCB (a bulky PCB), increased phase I enzyme parameters including the P-450 content, NADPH cytochrome c reductase activity and BaP oxidase activity. The glutathione S-transferase activity and glutathione content increased in HCB-treated mussels and decreased or remained the same as in the control in BaP- and TCB-exposed animals. Epoxide hydrolase (EH) activity increased in BaP- and HCB- but not in TCB-treated groups. These results show that, as in fish, only 3-methylcholanthrene P-450-type inducers (BaP and TCB, a non-ortho-substituted PCB) and not the phenobarbital P-450-type inducer (HCB, a di-ortho-substituted PCB) are effective inducers of phase I enzymes in mussel at the doses tested. Phase II activities were more sensitive to BaP and HCB than to TCB treatment.

Mixed-function oxygenase enzymes as tools for pollution monitoring: field studies on the French coast of the Mediterranean Sea.

1. MFO enzyme activities were measured in microsomes from whole mussels (Mytilus galloprovincialis) comber livers (Serranus cabrilla), or Posidonia oceanica etiolated tissues, and PAH contents were determined in sediments collected in coastal locations of the French Riviera and Corsica during 3 oceanographic cruises in 1987-1988. 2. BaP activities in mussel and EROD activities measured in fish were strongly correlated to the log of PAH content in sediments. The first results for CA4H in Posidonia showed significant differences related to PAH pollution levels. The increase in MFO activities measured in Corsica in summer 1988 indicated a recent petroleum contamination.

Scale of classification based on biochemical markers in mussels : application to pollution monitoring in mediterranean coasts and temporal trends

A battery of biochemical parameters was used to evaluate the response of mussels to a contaminated coastal environment. A multimarker approach was developed, establishing a scale for the classification of the water quality in European coastal sites (BIOMAR European programme). This study allows the evaluation of the temporal trends of this scale when applied to selected sites of European Mediterranean coast (BEEP Biological Effects of Environmental Pollution in Marine Coastal Ecosystems: European programme). Acetylcholinesterase activity (AChE) is highly sensitive to organophosphorus and carbamate insecticides and, to some extent, also to heavy metals. Catalase activity (CAT) and lipid oxidation (evaluated as malonedialdehyde) are markers of oxidative stress, glutathione S-transferase (GST) activity is related to conjugation of organic compounds and benzo(a)pyrene hydroxylase activity (BPH) is a marker of effect of certain planar organic compounds (e.g. polycyclic aromatic hydrocarbons, PAHs). These parameters were measured either in gills (AChE, GST) or digestive gland (BPH, GST, CAT, MDA). For each biomarker, a discriminatory factor was calculated (maximum variation range/confidence interval) and a response index was allocated. For each site, a Multimarker Pollution Index (MPI) was calculated as the sum of the response index of each of the five more discriminating biomarkers. As the result of our calculation method, the quality of the coastal environment at each site can be classified according to a five levels scale. Samples collected for five cruises in May 2001, 2002, 2003, and September 2001 and 2002 showed MPI evolutions. The results show that water quality can be classified from class 1 (clean areas in some sites of France, Italy and Spain) to class 4 (high pollution in main harbours). Results of the use of the biomarker scale in WP3 (Work Package Concernant Biomonitoring Programmes in Mediterranean Sea) during the BEEP programme make a strong contribution to the establishment of standardized strategies and methods for internationally agreed protocols for biomarker-based monitoring programmes. In comparison with scale pollution methodology used in the BIOMAR programme, the main contribution of BEEP was (1) to select from discriminatory analysis the biomarkers to be included in calculation of scale pollution; (2) to improve the use of the biomarker index in order to identify the main contaminants by analysis of individual contributions to the MPI; and (3) to apply methodology for temporal trends at sampled sites.

Benzo(a)pyrene hydroxylase activity in the marine mussel Mytilus galloprovincialis: a potential marker of contamination by polycyclic aromatic hydrocarbon-type compounds

Abstract The aim of this work is to optimize and standardize the incubation conditions necessary to determine benzo(a)pyrene hydroxylase (BPH) activity in mussel microsomes. Evidence is presented that the reaction is dependent on NADPH and linear with time, at least up to the incubation time used. To measure BPH activity with the highest efficiency, the concentrations of benzo(a)pyrene (70 μM) microsomal proteins (0–75 mg/0–8 ml) and NADPH (0.74 mM), and the incubation time (10 min) were optimized to avoid plateauing of the activity due to a lack of substrate or NADPH. The best compromise between signal/noise ratio and linearity of the reaction with time was considered. BPH induction in mussels treated with 3-methylcholanthrene or exposed to field contamination by polycyclic aromatic hydrocarbons (PAH)-type compounds demonstrated the ability of this technique to be a potential marker of exposure to PAH type compound.

Responses of antioxidants and lipid peroxidation in mussels to oxidative damage exposure.

1. The aim of this work was to evaluate the relationships between free radical scavengers and lipid peroxidation in the common mussel Mytilus edulis. 2. Mussels were exposed to compounds known for their ability to produce free radicals (carbon tetrachloride, CCl4) and reactive oxygen species via redox cycling (menadione) and the effects on digestive gland, gills and remaining tissues were studied. 3. Lipid peroxidation parameters and the status of free radical scavengers (glutathione, vitamins A, E and C) were affected more by exposure to menadione than to CCl4. 4. The observed changes in the free radical scavengers content are indicative of a role in detoxication of damaging reactive species.

Influence of temperature, pH, oxygenation, water-type and substrate on biomarker responses in the freshwater clam Corbicula fluminea (Müller)

We investigated the influence of abiotic factors on responses of components of detoxification metabolism of phases I and II, indicators related to oxidative stress and propionylcholinesterase, proposed as biomarkers of pollution in Corbicula fluminea. Combined effects of temperature (10 and 20 degrees C), water-type (water purified by reverse-osmosis, lake water from the collection site and tap water) and habitat substrate (presence and absence of sand) were assessed in a five-day experiment. Additionally, clams were exposed to hypoxia or submitted to acidic, neutral or alkaline conditions at 20 degrees C, in lake water, without sand, for five days. Responses of biomarkers were generally higher when clams were placed in tap water, except for level of peroxidised lipids (PL). Catalase (CAT) and NADH-cytochrome c reductase (NADH-red.) activities increased whereas propionylcholinesterase (PChE) activity decreased in absence of sand. Decreasing temperature resulted in depressing PChE and NADPH-cytochrome c reductase (NADPH-red.) activities. Hypoxia induced an increase of CAT activity and glutathione S-transferase activity towards ethacrynic acid and a decrease of PL level. CAT and NADH-red. activities as well as PL level were reduced when clams were exposed to acidic and/or alkaline conditions. These results indicate that effects of abiotic factors should be taken into account in environmental studies.