title: N-Acetyl-β-D-glucosaminidase activity in feral Carcinus maenas exposed to cadmium.
abstract: Cadmium is a priority hazardous substance, persistent in the aquatic environment, with the capacity to interfere with crustacean moulting. Moulting is a vital process dictating crustacean growth, reproduction and metamorphosis. However, for many organisms, moult disruption is difficult to evaluate in the short term, what limits its inclusion in monitoring programmes. N-acetyl-β-D-glucosaminidase (NAGase) is an enzyme acting in the final steps of the endocrine-regulated moulting cascade, allowing for the cast off of the old exoskeleton, with potential interest as a biomarker of moult disruption. This study investigated responses to waterborne cadmium of NAGase activity of Carcinus maenas originating from estuaries with different histories of anthropogenic contamination: a low impacted and a moderately polluted one. Crabs from both sites were individually exposed for seven days to cadmium concentrations ranging from 1.3 to 2000 μg/L. At the end of the assays, NAGase activity was assessed in the epidermis and digestive gland. Detoxification, antioxidant, energy production, and oxidative stress biomarkers implicated in cadmium metabolism and tolerance were also assessed to better understand differential NAGase responses: activity of glutathione S-transferases (GST), glutathione peroxidase (GPx) glutathione reductase (GR), levels of total glutathiones (TG), lipid peroxidation (LPO), lactate dehydrogenase (LDH), and NADP(+)-dependent isocitrate dehydrogenase (IDH). Animals from the moderately polluted estuary had lower NAGase activity both in the epidermis and digestive gland than in the low impacted site. NAGase activity in the epidermis and digestive gland of C. maenas from both estuaries was sensitive to cadmium exposure suggesting its usefulness for inclusion in monitoring programmes. However, in the digestive gland NAGase inhibition was found in crabs from the less impacted site but not in those from the moderately contaminated one. Altered glutathione levels were observed in cadmium-treated crabs from the contaminated site possibly conferring enhanced tolerance to these animals through its chelator action. Investigation of enhanced tolerance should thus be accounted for in monitoring programmes employing NAGase as biomarker to avoid data misinterpretation.
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal; ICBAS - Institute of Biomedical Sciences Abel Salazar, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal. Electronic address: smesquita@ciimar.up.pt.
authors.forename: Sofia Raquel
authors.initials: SR
authors.lastname: Mesquita
authors.affiliation: Faculty of Science, Ankara University, Department of Biology, 06100 Tandogan, Ankara, Turkey.
authors.forename: Şeyda Fikirdeşici
authors.initials: ŞF
authors.lastname: Ergen
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal; ICBAS - Institute of Biomedical Sciences Abel Salazar, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
authors.forename: Aurélie Pinto
authors.initials: AP
authors.lastname: Rodrigues
authors.affiliation: REQUIMTE, School of Engineering, Polytechnic Institute of Porto, Rua Dr. António Bernardino de Almeida 431, 4200-072 Porto, Portugal.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Oliva-Teles
authors.affiliation: REQUIMTE, School of Engineering, Polytechnic Institute of Porto, Rua Dr. António Bernardino de Almeida 431, 4200-072 Porto, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Delerue-Matos
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal. Electronic address: lguimaraes@ciimar.up.pt.
authors.forename: Laura
authors.initials: L
authors.lastname: Guimarães
mesh_terms: D000118:Acetylglucosaminidase / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003386:Brachyura / Q000187:drug effects* / Q000201:enzymology; D002104:Cadmium / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects; D015227:Lipid Peroxidation / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D015415:Biomarkers; D014874:Water Pollutants, Chemical; D002104:Cadmium; D000118:Acetylglucosaminidase
keywords: Anti-oxidant defences; Chitobiase; Environmental monitoring; Glutathione; Shore crab