Mauricette Gnassia-Barelli

Heavy metal distribution in different fish species from the Mauritania coast.

Cadmium, copper, zinc and mercury concentrations were determined in pelagic and benthic fishes from the Mauritania coast. The pelagic fishes consisted of the round sardinella Sardinella aurita (Clupeidae), the chub mackerel Scomber japonicus (Scombridae) and the Atlantic horse mackerel Trachurus trachurus (Carangidae). Four benthic species were considered, three Serranidae: the painted comber Serranus scriba, the golden grouper Epinephelus costae, and the Niger hind Cephalopholis nigri and one Mullidae: the West African goatfish Pseudupeneus prayensis. Cadmium, copper, zinc and mercury concentrations are low in the edible muscles of the pelagic species. In the benthic fishes, metals could be determined also in the gills and liver. Cadmium and copper were present in relatively low levels in the muscle (< or = 0.06 microgram Cd g-1 dry wt., < or = 1.6 micrograms Cu g-1 dry wt.) and gills (< or = 0.23 microgram Cd g-1, < or = 3.1 micrograms Cu g-1) and higher levels are encountered in the livers (< or = 51 micrograms Cd g-1, < or = 49.1 micrograms Cu g-1). Zinc concentrations in the muscle are low (< or = 20 micrograms Zn g-1 dry wt.), the concentrations in the gills (< or = 120 micrograms Zn g-1) approach those of the livers for C. nigri and P. prayensis or are higher in the case of S. scriba and E. costae. Mercury concentrations in the gills and muscle of the pelagic species are very low, higher quantities are found in the livers of the benthic species. The metal concentrations in all the fishes analysed, which are restricted to approximately 40 specimens, are low except those found for cadmium in the livers of the benthic fishes.

Cadmium and copper display different responses towards oxidative stress in the kidney of the sea bass Dicentrarchus labrax

Copper and cadmium were i.p. injected into the fish Dicentrarchus labrax. Cu as Cd-treated fish showed an enlargement of the lysosomal membrane of the kidney (pronephros), Cu being more toxic than Cd. Following injection, metal uptake, measured in muscle, liver and kidney, was much higher with cadmium treatment than with copper, the kidney being the main accumulating organ of cadmium in which metal accumulation is correlated with increased zinc level, suggesting metallothionein induction. In vivo exposure to metal decreases the lysosomal membrane stability of pronephros with a half dose of 127 ng g(-1) Cu and 735 ng g(-1) Cd. Lipid peroxidation, expressed as malondialdehyde equivalents (MDA), and catalase activity were measured in kidney subcellular fractions. When added in vitro, Cu significantly raises the MDA level (365% at 200 µM), Cd having a lower effect (20% at 500 µM). Catalase activity is significantly reduced by Cd whereas Cu does not produce any significant effect at the tested concentrations. Results suggest that although both metals cause in vivo damage to pronephros lysosomal membrane, Cu activates the redox process generating oxyradicals but does not affect in vitro the protective catalase activity unlike Cd which appears to weakly participate in oxyradical generation but alters in vitro protective catalase activity.

Evaluation of biomarkers in caged fishes and mussels to assess the quality of waters in a bay of the NW Mediterranean Sea

Specimens of sea bass (Dicentrarchus labrax) were placed in cages for 1 month in spring and autumn at different locations in the Bay of Cannes (NW Mediterranean). Biochemical markers evaluated were: ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities in fish livers and acetylcholinesterase (AChE) activity in fish muscle. EROD and GST activities were higher in front of the outlet for the wastewater plant of Cannes and in the harbour than outside the marina. High EROD and GST activities may be induced by petrol hydrocarbons and/or polychlorinated biphenyls (PCBs). AChE was low in the muscles of the fish caged in the harbour compared with samples from the other cages. Low AChE activity could suggest the presence of organophosphorus and carbamate compounds in seawater from the harbour. Mussels (Mytilus galloprovincialis) were caged off Cannes for the same periods as the fishes. Heavy metal, metallothionein (MT) concentrations and lysosomal membrane stability were evaluated in the digestive gland of the mussels. Results show low heavy metal and MT concentrations, implying low metal concentrations in the surrounding waters. High lysosomal membrane stability revealed a good physiological status of these animals after caging. The whole set of data indicates that seawater in the Bay of Cannes appeared to be unpolluted as regards pollutants which may induce the measured biomarkers, except in restricted areas.

Metal distribution in different tissues and in subcellular fractions of the Mediterranean clam Ruditapes decussatus treated with cadmium, copper, or zinc

Kinetics of accumulation of Cd (500 μg/l), Cu (150 μg/l) and Zn (1000 μg/l) were measured in organs (gills, digestive gland and remainder) of the clam Ruditapes decussatus. A significant accumulation was observed in the organs of animals treated with Cd or Cu, whereas no difference was obvious between controls and animals exposed to Zn. A slight increase was noted only in the gills of Zn-exposed animals. After subcellular fractionation, a major part of Cu and Cd found in the gills and in the digestive gland was associated with the cytosol, whereas zinc was mainly bound to the particulate fraction. Metallothionein (MT) concentrations were higher in the gills of Cu-treated animals than in those of controls or cadmium-exposed clams. As regards the digestive gland, no difference was found in MT concentrations of controls or of animals treated with Cu or Cd.

Effect of Heavy Metals on Lipid Peroxidation in the Mediterranean Clam Ruditapes decussatus

Abstract Lipid peroxidation (measured as malonedialdehyde MDA concentration) and peroxidizable lipids were measured in vitro in the gills and digestive gland of the Mediterranean clam Ruditapes decussatus incubated with cadmium, copper, and mercury. Cadmium had no effect on the basal peroxidation in the digestive gland and gills of R. decussatus until the concentration in the incubation medium reached 500 μg/ml. Basal peroxidation significantly increased with increasing copper concentration (6.25–25 μg/ml) in both organs, whereas stimulated peroxidation (peroxidizable lipids) decreased, particularly in the digestive gland. Mercury (0.005–5 μg Hg/ml) caused an increase in basal peroxidation whereas stimulated peroxidation did not change. In vivo experiments were carried out with 30 μg copper/l sea-water. In the digestive gland, basal lipid peroxidation increased significantly after 9 days of exposure compared to controls whereas stimulated peroxidation decreased compared to controls from day 4 to day 9 and then remained constant. In the gills, no significant differences were noted between control samples and treated ones except the peroxidizable lipids, which were lower at day 7. In vitro experiments indicated that cadmium, which does not undergo redox cycling, was found unable to stimulate the lipid peroxidation process, whereas copper and mercury may exist under different oxidation states and have detrimental effects on the antioxidant defence system of R. decussatus. Moreover, the results indicate that oxyradical generation occurs in vivo in the digestive gland tissue of the clam treated with copper.

Metallothionein determination in the liver of the sea bass Dicentrarchus labrax treated with copper and B(a)P

Metallothioneins (MTs) were quantified in the liver of the sea bass Dicentrarchus labrax treated by intraperitoneal injection of copper (500 ng g−1), of benzo(a)-pyrene (20 μg g−1), and of copper (500 ng g−1) and benzo(a)pyrene (20 μg g−1). Two methods of determination of MTs were used: differential pulse polarography and spectrophotometry. Results showed a good correlation between the MT levels determined by both methods. When fishes were injected with copper, their MT levels were lower than in the case of controls, probably due to the toxic effect of copper whereas when fishes were injected with both pollutants there was a 2-fold increase in MT level, compared to controls. In the case of injection with BaP alone, hepatic MT level was even lower than that of controls or in the fishes treated with copper.

Mercury and non-protein thiol compounds in the seagrass Posidonia oceanica.

Mercury concentrations, non-protein thiol levels and the enzyme activities of glutathione-S-transferase (GST) were measured in the blades and sheaths of the marine phanerogam Posidonia oceanica. The seagrass was collected in January and June and at three sites: the Bay of Rosignano (Italy) known for its mercury contamination, the north of the Lérins islands (Bay of Cannes, France), the Bay of Tonnara (Corsica, France). The two latter sites are considered as free of any known industrial inputs. Mercury concentrations and GST activities in both tissues were always higher in samples from Rosignano, particularly in June. Non-protein thiol levels were significantly higher in the blades than in the sheaths of P. oceanica from Tonnara and Lérins. In contrast, at Rosignano, the sheaths presented a significantly higher non-protein thiol concentration than the blades, particularly in June. Levels in the sheaths appeared to increase with the degree of pollution. Western Blot performed on sheaths of P. oceanica collected in June at Rosignano and Lérins revealed a characteristic band of GSTs at 31 kDa, proving the presence of the GST enzyme in this tissue. Mercury seemed to exert an influence upon non-protein thiol metabolism, including GST induction, in P. oceanica collected from the NW Mediterranean.

Chapter 13 – EVALUATION OF VARIOUS BIOMARKERS IN THE WILD FISH SERRANUS CABRILLA COLLECTED IN THE NW MEDITERRANEAN SEA.

Relationships between chemical contaminant exposure and alterations in several biochemical processes in fish may allow the use of certain biochemical parameters as markers (commonly referred to as biomarkers) of exposure and early responses to chemical contaminants. The measurement of biochemical and physiological responses to chemical contaminants in fish may serve to improve the assessment of biologically significant exposure to toxic anthropogenic chemicals and enhance the ability to assess the risk for effects on the health and survival of contaminant-exposed populations. Many field studies demonstrated the interest of the measurement of cytochrome P450 dependent MFO (mixed function oxidases), and among them EROD (ethoxy resorufin O-deethylase) activity induced by polycyclic aromatic hydrocarbons (PAHs), in fish as exposure biomarkers in the aquatic environment. Other biomarkers may be measured in marine animals : glutathione S-transferase (GST) activity, acetylcholinesterase (AChE) activity. It has been demonstrated that GSTs may be induced by both PAHs and polychlorobiphenyls (PCBs). AChE activity is inhibited in the presence of pesticides such as organophosphorous compounds and carbamates. A cruise “BIOMAR” was performed in autumn 1995 along the coasts of the NW Mediterranean and Corsica to collect many specimens of the comber Serranus cabrilla. Three biomarkers (EROD, GST and AChE) were measured in this fish (in the liver for EROD and GST, and in the muscle for AChE) as well as heavy metal concentrations (Cd, Cu, Hg and Zn, determined in the gills). The statistical treatment of the data (Principal Component Analysis performed with564 data) allowed to discriminate polluted areas from clean areas. Areas such as Cortiou (which is the cove where the treated waste waters from Marseilles are discharged) and North Planier (located in an area exposed to chemical contaminants) were affected by multiple sources of pollution (since high EROD, GST activities, low AChE activities and elevated metal concentrations were observed), whereas, in sites of Corsica, the source of pollution appeared to be unique, since petroleum contamination could be detectable in some samples (high EROD values). The results suggest that the complementary use of several biomarkers facilitates the evaluation of the possible sources of contamination in fish collected from the natural environment.