title: Exposure to the neurotoxic dinoflagellate, Alexandrium catenella, induces apoptosis of the hemocytes of the oyster, Crassostrea gigas.
abstract: This study assessed the apoptotic process occurring in the hemocytes of the Pacific oyster, Crassostrea gigas, exposed to Alexandrium catenella, a paralytic shellfish toxins (PSTs) producer. Oysters were experimentally exposed during 48 h to the toxic algae. PSTs accumulation, the expression of 12 key apoptotic-related genes, as well as the variation of the number of hemocytes in apoptosis was measured at time intervals during the experiment. Results show a significant increase of the number of hemocytes in apoptosis after 29 h of exposure. Two pro-apoptotic genes (Bax and Bax-like) implicated in the mitochondrial pathway were significantly upregulated at 21 h followed by the overexpression of two caspase executor genes (caspase-3 and caspase-7) at 29 h, suggesting that the intrinsic pathway was activated. No modulation of the expression of genes implicated in the cell signaling Fas-Associated protein with Death Domain (FADD) and initiation-phase (caspase-2) was observed, suggesting that only the extrinsic pathway was not activated. Moreover, the clear time-dependent upregulation of five (Bcl2, BI-1, IAP1, IAP7B and Hsp70) inhibitors of apoptosis-related genes associated with the return to the initial number of hemocytes in apoptosis at 48 h of exposure suggests the involvement of strong regulatory mechanisms of apoptosis occurring in the hemocytes of the Pacific oyster.
authors: Institut National des Sciences et Technologies de la Mer, Laboratoire Milieu Marin, 28 rue du 2 mars 1934, Salammbô 2025, Tunisia. jean.luc.rolland@ifremer.fr.
authors: Walid
authors: W
authors: Medhioub
authors: Simon
authors: S
authors: Ramondenc
authors: Audrey Sophie
authors: AS
authors: Vanhove
authors: Agnes
authors: A
authors: Vergnes
authors: Estelle
authors: E
authors: Masseret
authors: Veronique
authors: V
authors: Savar
authors: Zouher
authors: Z
authors: Amzil
authors: Mohamed
authors: M
authors: Laabir
authors: Jean Luc
authors: JL
authors: Rolland
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D049896:Crassostrea / Q000378:metabolism / Q000502:physiology*; D004141:Dinoflagellida / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism; D006434:Hemocytes / Q000473:pathology*; D008387:Marine Toxins / Q000506:poisoning*; D010125:Ostreidae / Q000378:metabolism / Q000502:physiology*; D057096:Shellfish Poisoning / Q000378:metabolism / Q000473:pathology*; D015854:Up-Regulation / Q000502:physiology; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D053200:Fas-Associated Death Domain Protein; D008387:Marine Toxins; D051028:bcl-2-Associated X Protein; D020169:Caspases