Publications by authors named "Samuel Koenig"

Organisms inhabiting submarine canyons can be potentially exposed to higher inputs of anthropogenic chemicals than their counterparts from the adjacent areas. To find out to what extend this observation applies to a NW Mediterranean canyon (i.e.

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Article Synopsis
  • Seven deep-sea fish species were studied in the Blanes Canyon, measuring metal concentrations in their livers and determining their detoxification capabilities using metallothionein (MT) levels.
  • The study found that the metal levels in these fish were comparable to those found in similar species from the Atlantic and hydrothermal vent areas.
  • The impact of these metals on fish physiology was assessed through enzyme activities, revealing that metal contamination affected baseline activity levels of enzymes such as acetylcholinesterase (AChE) and lactate dehydrogenase (LDH).
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The measurement of enzymatic activities involved in xenobiotic biotransformation was carried out in adults of Solea solea and Solea senegalensis. The hepatic enzymes analysed were cytochrome P450 (CYP) related activities using eight fluorometric substrates and carboxylesterases (CbE). The conjugating activities of glutathione S-transferase (GST) and UPD-glucuronosyltransferase (UDPGT) were also assessed.

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Biliary polycyclic aromatic hydrocarbon (PAH) and alkylphenol (AP) metabolites, hepatic gene expression, and corresponding enzyme activities were determined in the deep-sea fish Alepocephalus rostratus from two sites within the Mediterranean. Biliary metabolites included the hydroxylated PAH metabolites (OH-PAHs) 1-naphthol, 2-naphthol, 9-fluorenol, 9-phenanthrol, and 1-pyrenol and the APs 4-nonylphenol (NP) and 4-tert-octylphenol (OP). Five biomarker genes, namely, cytochrome P450 1A (CYP1A), vitellogenin (Vtg), catalase (CAT), Cu/Zn-superoxide-dismutase (Cu/Zn-SOD), and glutathione reductase (GR), were quantified using qRT-PCR.

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The levels and profiles of organochlorine (OC) contaminants, including polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs) and penta- (PeCB) and hexachlorobenzene (HCB), as well as polybrominated diphenyl ethers (PBDEs) were determined in muscle samples of the deep-sea fish Alepocephalus rostratus, Coelorinchus mediterraneus and Lepidion lepidion and the red-shrimp Aristeus antennatus from the NW Mediterranean Sea. Mean PCB and DDT levels ranged from the highest concentrations in the fish A. rostratus (Σ(7)PCBs 6.

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A number of studies have found high levels of mercury (Hg) in deep-sea organisms throughout the world's oceans, but the underlying causes are not clear as there is no consensus on the origin and cycling of Hg in the ocean. Recent findings suggested that Hg accumulation may increase with increasing forage depth and pointed to the deep-water column as the origin of most Hg in marine biota, especially its organic methylmercury (MeHg) form. In the present study, we determined the total mercury (THg) levels in 12 deep-sea fish species and a decapod crustacean and investigated their relationship with the species' nitrogen stable isotope ratio (δ(15)N) as an indicator of their trophic level, average weight and habitat depth.

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Biomarker assays are widely used as proxies for contaminant-induced effects in aquatic organisms. However, in many cases, their intrinsic natural variability due to exogenous and endogenous factors makes the interpretation of biomarker data difficult. In the present study, we investigated the natural fluctuations of six hepatic biomarkers, namely ethoxyresorufin-O-deethylase (EROD) in fish and pentoxyresorufin-O-deethylase (PROD) in crustacea, catalase (CAT), carboxylesterase (CbE), glutathione-S-transferase (GST), total glutathione peroxidase (GPX) and glutathione reductase (GR) in two deep-sea fish species, namely Alepocephalus rostratus and Lepidion lepidion and the decapod crustacean Aristeus antennatus.

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Variations in cytochrome P450 enzyme (CYPs) distribution and function between animal groups could result in differential metabolism and elimination kinetics for certain contaminants. Although a number of studies have suggested that differences in polychlorobiphenyl (PCB) accumulation profiles between crustacea and fish might result from differential CYP patterns, the relationship between PCB bioaccumulation and CYP capacities has not been demonstrated in these organisms. In the present study we investigated the hepatic microsomal catalytic activities in three deep-sea fish species, Alepocephalus rostratus (Alepocephalidae), Coelorinchus mediterraneus (Macrouridae), and Lepidion lepidion (Moridae), and the decapod crustacean Aristeus antennatus (Decapoda), using six fluorescent CYP-mediated substrates, namely ER (7-ethoxyresorufin), PR (7-pentoxyresorufin), BR (7-benzyloxyresorufin), CEC (3-cyano-7-ethoxycoumarin), DBF (dibenzylfluorescein) and BFC (7-benzyloxy-4-trifluoromethylcoumarin).

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Two novel, non-destructive assays were developed to evaluate contaminant-induced lipid peroxidation (thiobarbituric acid-reacting substances, TBARS, levels) and haem biosynthesis disruption (porphyrin excretion) in decapod crabs. A laboratory experiment was conducted whereby pie-crust crabs (Cancer novaezelandiae) were fed cockles (Austrovenus stutchburyi) collected from a contaminated and reference site and TBARS levels and porphyrin excretion determined using fluorometric analysis in urine samples. Pyrene metabolite levels were also measured in the same urine samples to assess polycyclic aromatic hydrocarbon (PAH) exposure.

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The detection of urinary polycyclic aromatic hydrocarbon (PAH) metabolites by fluorescence spectrophotometry is particularly effective as a practical means to assess PAH exposure in decapod crabs. However, the practical application of this technique has thus far only been tested for the European shore crab (Carcinus maenas) and only a few field studies have been conducted in heavily polluted areas. The present study evaluated the adaptability of this method as a rapid, cost-effective and non-destructive biomonitoring tool for the New Zealand crab species, Macrophthalmus hirtipes (stalk-eyed mud crab).

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