title: Induction of apoptosis by UV in the flat oyster, Ostrea edulis.
abstract: Apoptosis is a fundamental feature in the development of many organisms and tissue systems. It is also a mechanism of host defense against environmental stress factors or pathogens by contributing to the elimination of infected cells. Hemocytes play a key role in defense mechanisms in invertebrates and previous studies have shown that physical or chemical stress can increase apoptosis in hemocytes in mollusks. However this phenomenon has rarely been investigated in bivalves especially in the flat oyster Ostrea edulis. The apoptotic response of hemocytes from flat oysters, O. edulis, was investigated after exposure to UV and dexamethasone, two agents known to induce apoptosis in vertebrates. Flow cytometry and microscopy were combined to demonstrate that apoptosis occurs in flat oyster hemocytes. Investigated parameters like intracytoplasmic calcium activity, mitochondrial membrane potential and phosphatidyl-serine externalization were significantly modulated in cells exposed to UV whereas dexamethasone only induced an increase of DNA fragmentation. Morphological changes were also observed on UV-treated cells using fluorescence microscopy and transmission electron microscopy. Our results confirm the apoptotic effect of UV on hemocytes of O. edulis and suggest that apoptosis is an important mechanism developed by the flat oyster against stress factors.
authors.affiliation: Institut Français de Recherche pour l'Exploitation de la Mer (Ifremer), Unité Santé Génétique et Microbiologie des Mollusques (SG2M), Laboratoire Génétique et Pathologie des Mollusques Marins (LGPMM), Avenue de Mus de Loup, 17390 La Tremblade, France.
authors.forename: Ophélie
authors.initials: O
authors.lastname: Gervais
authors.affiliation: Institut Français de Recherche pour l'Exploitation de la Mer (Ifremer), Unité Santé Génétique et Microbiologie des Mollusques (SG2M), Laboratoire Génétique et Pathologie des Mollusques Marins (LGPMM), Avenue de Mus de Loup, 17390 La Tremblade, France.
authors.forename: Tristan
authors.initials: T
authors.lastname: Renault
authors.affiliation: Institut Français de Recherche pour l'Exploitation de la Mer (Ifremer), Unité Santé Génétique et Microbiologie des Mollusques (SG2M), Laboratoire Génétique et Pathologie des Mollusques Marins (LGPMM), Avenue de Mus de Loup, 17390 La Tremblade, France. Electronic address: iarzul@ifremer.fr.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Arzul
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D003907:Dexamethasone / Q000494:pharmacology; D006434:Hemocytes / Q000187:drug effects / Q000528:radiation effects; D049895:Ostrea / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D000893:Anti-Inflammatory Agents; D003907:Dexamethasone
keywords: Apoptosis; Flow cytometry; Hemocyte(s); Microscopy; Ostrea edulis; Oyster; UV