title: Brown muscle disease: impact on Manila clam Venerupis (=Ruditapes) philippinarum biology.
abstract: This study assessed the effect of Brown Muscle Disease (BMD) on Manila clam Venerupis philippinarum fitness. BMD was discovered in 2005. It affects the posterior adductor muscle and leads to clam gaping and eventually death. Three statuses of clams were compared: buried individuals with no signs of BMD (BUR); clams at the surface of the sediment with no signs of BMD (SURF) and clams at the surface of the sediment exhibiting signs of brown muscle disease (BMD). Physiological (condition index), immune (hemocyte parameters) and molecular (gene expressions) parameters collected seasonally were analyzed and compared. Results demonstrated a seasonal pattern in condition index (CI) with peaks in spring/summer and decreases in autumn/winter. At each season, the highest CI was observed in BUR and the lowest CI was observed in BMD. In terms of immune response, phagocytosis rate and capacity were higher in clams with BMD whereas the health status of the clams did not influence the total hemocyte count. Genes involved in the immune system (comp, tnf, inter) were upregulated in clams with BMD. The molecular analysis of gill and posterior muscle showed higher mitochondrial metabolism (cox-1, 16S) in cells of infected clams, suggesting a stronger energetic demand by these cells. Finally, genes involved in oxidative stress response (cat, sod), detoxification (mt) and DNA repair (gadd45) were also overexpressed due to reactive oxygen species production. Most of the studied parameters underlined a cause-effect correlation between Manila clam health status (BUR, SUR, BMD) and physiological parameters. An important stress response was observed in BMD-infected clams at different scales, i.e. condition index, immune parameters and stress-related gene expression.
authors.affiliation: Université Bordeaux, EPOC, UMR 5805, 33120 Arcachon, France. Electronic address: cindy.binias@gmail.com.
authors.forename: Cindy
authors.initials: C
authors.lastname: Binias
authors.affiliation: CNRS, EPOC, UMR 5805, 33120 Arcachon, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Gonzalez
authors.affiliation: Université Bordeaux, EPOC, UMR 5805, 33120 Arcachon, France.
authors.forename: Margot
authors.initials: M
authors.lastname: Provost
authors.affiliation: LEMAR CNRS (UMR 6539), IUEM, Université de Bretagne occidentale, 29280 Plouzané, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Lambert
authors.affiliation: Université Bordeaux, EPOC, UMR 5805, 33120 Arcachon, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: de Montaudouin
mesh_terms: D056893:Alveolata / Q000502:physiology; D000818:Animals; D049872:Bivalvia / Q000235:genetics / Q000276:immunology / Q000469:parasitology / Q000502:physiology*; D001823:Body Composition; D005602:France; D005786:Gene Expression Regulation; D019015:Geologic Sediments; D005880:Gills / Q000469:parasitology / Q000473:pathology; D006434:Hemocytes / Q000469:parasitology / Q000473:pathology; D007113:Immunity, Innate; D009132:Muscles / Q000469:parasitology / Q000473:pathology; D012621:Seasons
keywords: Brown muscle disease; Condition index; Immune response; Oxidative stress; Venerupis philippinarum