title: Physiological and pathological changes in the eastern oyster Crassostrea virginica infested with the trematode Bucephalus sp. and exposed to the toxic dinoflagellate Alexandrium fundyense.
abstract: Effects of experimental exposure to Alexandrium fundyense, a Paralytic Shellfish Toxin (PST) producer known to affect bivalve physiological condition, upon eastern oysters, Crassostrea virginica with a variable natural infestation of the digenetic trematode Bucephalus sp. were determined. After a three-week exposure to cultured A. fundyense or to a control algal treatment with a non-toxic dinoflagellate, adult oysters were assessed for a suite of variables: histopathological condition, hematological variables (total and differential hemocyte counts, morphology), hemocyte functions (Reactive Oxygen Species (ROS) production and mitochondrial membrane potential), and expression in gills of genes involved in immune responses and cellular protection (MnSOD, CAT, GPX, MT-IV, galectin CvGal) or suspected to be (Dominin, Segon). By comparing individual oysters infested heavily with Bucephalus sp. and uninfested individuals, we found altered gonad and digestive gland tissue and an inflammatory response (increased hemocyte concentration in circulating hemolymph and hemocyte infiltrations in tissues) associated with trematode infestation. Exposure to A. fundyense led to a higher weighted prevalence of infection by the protozoan parasite Perkinsus marinus, responsible for Dermo disease. Additionally, exposure to A. fundyense in trematode-infested oysters was associated with the highest prevalence of P. marinus infection. These observations suggest that the development of P. marinus infection was advanced by A. fundyense exposure, and that, in trematode-infested oysters, P. marinus risk of infection was higher when exposed to A. fundyense. These effects were associated with suppression of the inflammatory response to trematode infestation by A. fundyense exposure. Additionally, the combination of trematode infestation and A. fundyense exposure caused degeneration of adductor muscle fibers, suggesting alteration of valve movements and catch state, which could increase susceptibility to predation. Altogether, these results suggest that exposure of trematode-infested oysters to A. fundyense can lead to overall physiological weakness that decrease oyster defense mechanisms.
authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS/IRD/IFREMER, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France. Electronic address: Malwenn.Lassudrie@gmail.com.
authors: Malwenn
authors: M
authors: Lassudrie
authors: Northeast Fisheries Science Center, NOAA National Marine Fisheries Service, 212 Rogers Avenue, Milford, CT 06460, USA.
authors: Gary H
authors: GH
authors: Wikfors
authors: State of Connecticut, Department of Agriculture, Bureau of Aquaculture, P.O. Box 97, Milford, CT 06460, USA.
authors: Inke
authors: I
authors: Sunila
authors: Northeast Fisheries Science Center, NOAA National Marine Fisheries Service, 212 Rogers Avenue, Milford, CT 06460, USA.
authors: Jennifer H
authors: JH
authors: Alix
authors: Northeast Fisheries Science Center, NOAA National Marine Fisheries Service, 212 Rogers Avenue, Milford, CT 06460, USA.
authors: Mark S
authors: MS
authors: Dixon
authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS/IRD/IFREMER, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Doriane
authors: D
authors: Combot
authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS/IRD/IFREMER, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Philippe
authors: P
authors: Soudant
authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS/IRD/IFREMER, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Caroline
authors: C
authors: Fabioux
authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), UBO/CNRS/IRD/IFREMER, rue Dumont d'Urville, technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Hélène
authors: H
authors: Hégaret
mesh_terms: D000818:Animals; D049896:Crassostrea / Q000276:immunology / Q000469:parasitology*; D004141:Dinoflagellida / Q000502:physiology*; D006458:Hemolymph / Q000166:cytology; D006790:Host-Parasite Interactions; D053078:Membrane Potential, Mitochondrial; D017382:Reactive Oxygen Species / Q000378:metabolism; D014200:Trematoda / Q000502:physiology*
chemical_list: D017382:Reactive Oxygen Species
keywords: Alexandrium fundyense; Bucephalus sp.; Crassostrea virginica; Host–pathogen interaction; Perkinsus marinus