Stefano Bonacci

Cholinesterases in the Antarctic scallop Adamussium colbecki: Characterization and sensitivity to pollutants

Antarctica is affected by man-made contamination and development of sensitive ecotoxicological tools for impact assessment is a priority task. The aims of the present study were to characterize cholinesterase (ChE) activities in an Antarctic key species, the scallop Adamussium colbecki, and to investigate their sensitivity as biological markers (biomarkers) of exposure to pollutants and of their effects. Our results show that ChEs in gills share most characteristics with true acetylcholinesterase. The present results show that ChE activities in A. colbecki are significantly inhibited by organophosphates (OPs) and somehow affected by in vitro exposure to mixtures of marine contaminants such as polycyclic aromatic hydrocarbons (PAHs), even if no concentration-dependent pattern of response was observed and no effect was elicited by polychlorinated biphenyls (PCBs). The present results do not demonstrate ChEs in A. colbecki as sensitive tools to measure exposure to the above chemicals, but they may be worthy of further study considering the importance of the scallop in Antarctic marine ecosystems and its suitability as a sentinel species.

Induction of EROD activity in European eel (Anguilla anguilla) experimentally exposed to benzo[a]pyrene and β-naphthoflavone

The induction of liver ethoxyresorufin O-deethylase (EROD) activity was investigated in the European eel, Anguilla anguilla, collected from a Mediterranean brackish environment and experimentally exposed to benzo[a]pyrene (B[a]P) and beta-naphthoflavone (BNF). Eels were injected intraperitoneally at increasing doses (0.1, 1, 10, and 50 mg/kg wet body weight) using corn oil as a carrier and sacrificed after 7 days. The main objectives of the present study are: (1). to assess of the sensitivity of EROD induction as a biomarker to polycyclic aromatic hydrocarbon (PAH) exposure; (2). to determine an EROD dose-response relationship of the contaminants used; and (3). to compare the efficiency of B[a]P and BNF as inducers of EROD activity. Results showed that both chemicals resulted in a dose-dependent EROD induction, but increases were not linear. EROD activity seemed to reach a plateau at the exposure of 10 mg/kg in both treatment groups; B[a]P was a more potent inducer than BNF was at the higher doses (10 and 50 mg/kg), while the opposite result was observed at the lower ones (0.1 and 1 mg/kg). The greatest induction occurred in eels treated with 10 mg/kg B[a]P, in which a 261-fold increase in EROD activity was observed. Results showed that EROD activity in A. anguilla is significantly induced by B[a]P and BNF exposure, responding to a wide range of concentrations of these contaminants. We infer that this tool may be suited as a diagnostic biomarker for biomonitoring PAHs pollution in Mediterranean brackish environments and further field research is suggested.

Biomonitoring Aquatic Environmental Quality in a Marine Protected Area: A Biomarker Approach

Abstract The main aims of the present study, conducted in the framework of the MONIQUA–Egadi Scientific Project, were twofold: first, to make the first step in the development and validation of an ecotoxicological approach for the assessment of marine pollution in coastal environments on the basis of a set of biomarker responses in new sentinel species; and second, to obtain preliminary information on environmental quality in an Italian marine protected area, the Egadi Islands (Sicily). Several cytochrome P450–dependent mixed-function oxidase activities were measured in the following sentinel species: rainbow wrasse Coris julis, gastropod limpet Patella caerulea, and sea urchin Paracentrotus lividus. The results suggest that specimens from the Favignana Harbor may be exposed to P450 inducers, whereas most of the other sites seem to share similar environmental quality. The proposed approach has potential for assessment of environmental quality in marine protected areas.

Cholinesterase activities in the adductor muscle of the Antarctic scallop Adamussium colbecki

Antarctica is regarded as one of the most pristine parts of the Earth but even this remote ecosystem is affected by contamination and high levels of certain heavy metals, such as cadmium, which may occur naturally in Antarctic waters. The bivalve scallop Adamussium colbecki is considered a key species of Antarctic benthic ecosystems and a sensitive target for bioaccumulation of xenobiotics and metals. Since cholinesterases (ChEs) in the adductor muscle of A. colbecki presumably play a prominent physiological role through regulation of swimming movements, the main aims of this study was to characterize ChE activities in adductor muscle of A. colbecki and to investigate their sensitivity to organophosphate pesticides and heavy metals. The results suggest that an acetylcholinesterase-like enzyme in the adductor muscle of the scallop has low sensitivity to organophosphates but was significantly inhibited by exposure to cadmium.

Seasonal screening of AChE, GSH and gonad histology, in European sea bass Dicentrarchus labrax L. reared in three different fish farms

The aim of this work was to do a preliminary seasonal screening of ecotoxicological biomarkers in European sea bass Dicentrarchus labrax in three different fish farms, to know if the different location and typology can discriminate them. A set of selected biomarkers of xenobiotic exposure, such as acetylcholinesterase (AChE) activity, Glutathione (GSH) and gonad morphology were investigated seasonally in male European sea bass D. labrax (L.) reared in three different intensive farms: a land-based farm of cement tanks (T), an in-shore sea cages farm (C1) and an off-shore sea cages farm (C2). The results showed that both location and typology can discriminate AChE activity, GSH content and gonad morphology. Further investigation is needed to propose these biomarkers in the protocol of fish farm quality control.

Screening of ecotoxicological, qualitative and reproductive variables in male European sea bass Dicentrarchus labrax (L.) reared in three different fish farms: Facility location and typology

The aim of this study was to investigate the influence of both facility location and typology of fish farm on some ecotoxicological, qualitative and reproductive variables in European sea bass Dicentrarchus labrax L. Several variables were investigated: gonado-somatic index (GSI), liver-somatic index (LSI); 7-ethoxyresorufin-O-deethylase (EROD), benzo(a)pyrene monooxygenase and acetylcholinesterase activities; glutathione (GSH), testosterone, 17β-estradiol, total lipid, phospholipid (PL) and triglyceride contents. In addition, the histological sections of gonads were examined. Results suggest that LSI, EROD activity, GSI, GSH, PL, hormone levels and gonad morphology were influenced by different facility locations and typologies of fish farm.

Preliminary investigation on cholinesterases activity in Adamussium colbecki from Terra Nova Bay: Field and laboratory study

While the inhibition of cholinesterase (ChE) activity as a biomarker of exposure to neurotoxic insecticides is well established in aquatic invertebrates of temperate areas, little is known about organisms from polar regions including Antarctica. Cholinesterase activity was investigated in specimens of the Antarctic scallop, Adamussium colbecki, collected in winter 2000 at Campo Icaro (Ross Sea, Antarctica) for preliminary characterization of a potentially new biomarker. Characterization of various ChE enzymes using specific substrates including an acetylthiocholine iodide (ASCh) and a butyrylthiocholine iodide (BSCh) was performed in gills, digestive gland and adductor muscle of the scallop. The effect of in vivo Zn2+ exposure in gills and digestive gland of A. colbecki was also studied. All the tissues expressed ChE activity (gill > adductor muscle > digestive gland) in accordance with data reported for marine mussels (Mytilus sp.) from temperate areas (1.1–13.8 nmol min−1 mg protein−1). Significant BSCh-dependent ChE inhibition was also measured with a specific inhibitor, Iso-OMPA. Exposure to Zn2+ does not seem to affect ChE activity in the scallop although some slight differences were observed in substrate specificities (ASCh and BSCh) between treated and untreated organisms. This preliminary study stresses the need for further investigation on ChE activity in A. colbecki as a biomarker for monitoring water contamination in the marine Antarctic environment.

PCB Muscle Content and Liver EROD Activity in the European EEL (Anguilla Anguilla) Treated with Aroclor 1254

The European eel (Anguilla anguilla) is a euryaline fish suitable for investigating exposure, accumulation patterns and biological effects of lipophilic pollutants such as polychlorinated biphenyls (PCBs). Eels were collected from the Orbetello Lagoon (Tyrrhenian coast of Italy) and injected with increasing doses of Aroclor 1254 to better characterise EROD activity as biomarker in eels from Mediterranean brackish environments. Fish muscle was analysed for PCB content and EROD activity was measured in liver microsomiaI fraction. Significant differences of PCB levels were observed in exposed fish (p < 0.05) while EROD activity increased significantly reaching the highest values at the maximum dose of 50mg/Kg (p < 0.001). Highly positive correlation (r = 0.82; p < 0.01) was found between PCB content and EROD activity. Isomer profiles showed decreases in hexa-CBs. The European eel is confirmed to be a useful sentinel species for assessing pollution in brackish environments whereas EROD activity is characterised as a sensitive biomarker of exposure for PCB mixtures.