title: The toxic dinoflagellate Alexandrium minutum disrupts daily rhythmic activities at gene transcription, physiological and behavioral levels in the oyster Crassostrea gigas.
abstract: The objective of the present work was to study the effect of the harmful alga Alexandrium minutum on the daily rhythm of the oyster Crassostrea gigas. Many metabolic and physiological functions are rhythmic in living animals. Their cycles are modeled in accordance with environmental cycles such as the day/night cycle, which are fundamental to increase the fitness of an organism in its environment. A disruption of rhythmic activities is known to possibly impact the health of an animal. This study focused in C. gigas, on a gene known to be involved in circadian rhythmicity, cryptochrome gene (CgCry), on putative clock-controlled genes involved in metabolic and physiological functions, on the length cycle of the style, a structure involved in digestion, and on the rhythmicity of valve activity involved in behavior. The results indicate that daily activity is synchronized at the gene level by light:dark cycles in C. gigas. A daily rhythm of valve activity and a difference in crystalline style length between scotophase and photophase were also demonstrated. Additionally, A. minutum exposure was shown to alter cyclic activities: in exposed oysters, gene transcription remained at a constant low level throughout a daily cycle, valve opening duration remained maximal and crystalline style length variation disappeared. The results show that a realistic bloom of A. minutum clearly can disrupt numerous and diverse molecular, physiological and behavioral functions via a loss of rhythmicity.
authors.affiliation: CNRS, EPOC, UMR 5805, F-33120 Arcachon, France. Electronic address: d.tran@epoc.u-bordeaux1.fr.
authors.forename: Damien
authors.initials: D
authors.lastname: Tran
authors.affiliation: CNRS, EPOC, UMR 5805, F-33120 Arcachon, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Ciutat
authors.affiliation: CNRS, EPOC, UMR 5805, F-33120 Arcachon, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Mat
authors.affiliation: CNRS, EPOC, UMR 5805, F-33120 Arcachon, France.
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Massabuau
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (UMR 6539, LEMAR), IUEM/UBO, Technopole Brest Iroise, Plouzané, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Hégaret
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (UMR 6539, LEMAR), IUEM/UBO, Technopole Brest Iroise, Plouzané, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Lambert
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (UMR 6539, LEMAR), IUEM/UBO, Technopole Brest Iroise, Plouzané, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Le Goic
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (UMR 6539, LEMAR), IUEM/UBO, Technopole Brest Iroise, Plouzané, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Soudant
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D049896:Crassostrea / Q000187:drug effects*; D056931:Cryptochromes / Q000235:genetics* / Q000378:metabolism; D004141:Dinoflagellida / Q000737:chemistry* / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D008387:Marine Toxins / Q000633:toxicity*; D017440:Photoperiod; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D056931:Cryptochromes; D008387:Marine Toxins; D014874:Water Pollutants, Chemical
keywords: Alexandrium minutum; Crassostrea gigas; Cyclic activities disruption; Daily rhythm; Harmful algal bloom