title: Physiological responses of Manila clams Venerupis (=Ruditapes) philippinarum with varying parasite Perkinsus olseni burden to toxic algal Alexandrium ostenfeldii exposure.
abstract: Manila clam stock from Arcachon Bay, France, is declining, as is commercial harvest. To understand the role of environmental biotic interactions in this decrease, effects of a toxic dinoflagellate, Alexandrium ostenfeldii, which blooms regularly in Arcachon bay, and the interaction with perkinsosis on clam physiology were investigated. Manila clams from Arcachon Bay, with variable natural levels of perkinsosis, were exposed for seven days to a mix of the nutritious microalga T-Iso and the toxic dinoflagellate A. ostenfeldii, a producer of spirolides, followed by seven days of depuration fed only T-Iso. Following sacrifice and quantification of protozoan parasite Perkinsus olseni burden, clams were divided into two groups according to intensity of the infection ("Light-Moderate" and "Moderate-Heavy"). Hemocyte and plasma responses, digestive enzyme activities, antioxidant enzyme activities in gills, and histopathological responses were analyzed. Reactive oxygen species (ROS) production in hemocytes and catalase (CAT) activity in gills increased with P. olseni intensity of infection in control clams fed T-Iso, but did not vary among A. ostenfeldii-exposed clams. Exposure to A. ostenfeldii caused tissue alterations associated with an inflammatory response and modifications in hemocyte morphology. In the gills, superoxide dismutase (SOD) activity decreased, and an increase in brown cell occurrence was seen, suggesting oxidative stress. Observations of hemocytes and brown cells in tissues during exposure and depuration suggest involvement of both cell types in detoxication processes. Results suggest that exposure to A. ostenfeldii disrupted the pro-/anti-oxidant response of clams to heavy P. olseni intensity. In addition, depressed mitochondrial membrane potential (MMP) in hemocytes of clams exposed to A. ostenfeldii suggests that mitochondrial functions are regulated to maintain homeostasis of digestive enzyme activity and condition index.
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Malwenn
authors.initials: M
authors.lastname: Lassudrie
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Soudant
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Richard
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Henry
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France; Laboratoire Phycotoxines, Ifremer, Institut Français de Recherche pour l'Exploitation de la Mer, BP 21105, 44311 Nantes CEDEX3, France; Laboratoire Milieu Marin, INSTM, Institut National des Sciences et Technologies de la Mer, 28 rue du 2 mars 1934, 2025 Salammbô, Tunisie.
authors.forename: Walid
authors.initials: W
authors.lastname: Medhioub
authors.affiliation: Laboratory of Immunology and Pathology of Invertebrates, Department of Molecular Biology, Exact and Natural Sciences Center, Federal University of Paraíba-Campus I, 58051-900 João Pessoa, PB, Brazil.
authors.forename: Patricia Mirella
authors.initials: PM
authors.lastname: da Silva
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Donval
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Bunel
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Le Goïc
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Lambert
authors.affiliation: Université de Bordeaux UMR 5805 EPOC, station marine d'Arcachon, 2 rue du Pr Jolyet, 33120 Arcachon, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: de Montaudouin
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Fabioux
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France. Electronic address: Helene.Hegaret@univ-brest.fr.
authors.forename: Hélène
authors.initials: H
authors.lastname: Hégaret
mesh_terms: D056893:Alveolata / Q000502:physiology*; D000818:Animals; D049872:Bivalvia / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism / Q000469:parasitology*; D004141:Dinoflagellida / Q000737:chemistry*; D004789:Enzyme Activation / Q000187:drug effects; D005602:France; D005880:Gills / Q000187:drug effects; D006434:Hemocytes / Q000187:drug effects; D008387:Marine Toxins / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D008928:Mitochondria / Q000187:drug effects; D010088:Oxidoreductases / Q000378:metabolism; D059208:Parasite Load; D017382:Reactive Oxygen Species; D013141:Spiro Compounds / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D014874:Water Pollutants, Chemical
chemical_list: D008387:Marine Toxins; D017382:Reactive Oxygen Species; D013141:Spiro Compounds; D014874:Water Pollutants, Chemical; D010088:Oxidoreductases
keywords: Alexandrium ostenfeldii; Bivalve; Harmful algal bloom; Oxidative stress; Perkinsus olseni; Venerupis philippinarum