FN Archimer Export Format PT J TI Exposure to the toxic dinoflagellate Alexandrium catenella modulates juvenile oyster Crassostrea gigas hemocyte variables subjected to different biotic conditions BT AF LASSUDRIE, Malwenn SOUDANT, Philippe NICOLAS, Jean-Louis MINER, Philippe LE GRAND, Jacqueline LAMBERT, Christophe LE GOIC, Nelly HEGARET, Helene FABIOUX, Caroline AS 1:1;2:1;3:2;4:2;5:2;6:1;7:1;8:1;9:1; FF 1:;2:;3:PDG-RBE-PFOM-PI;4:PDG-RBE-PFOM-PI;5:PDG-RBE-PFOM-PI;6:;7:;8:;9:; C1 IFREMER, Lab Sci Environm Marin LEMAR, UMR 6539, CNRS,UBO,IRD,Inst Univ Europeen Mer, Technopole Brest Iroise,Rue Dumont Urville, F-29280 Plouzane, France. IFREMER, Lab Sci Environm Marin LEMAR, UMR 6539, CNRS,UBO,IRD,Lab Physiol Invertebres, Technopole Brest Iroise BP 70, F-29280 Plouzane, France. C2 UBO, FRANCE IFREMER, FRANCE SI BREST SE PDG-RBE-PFOM-PI UM LEMAR IN WOS Ifremer jusqu'en 2018 copubli-france copubli-univ-france IF 3.148 TC 13 UR https://archimer.ifremer.fr/doc/00314/42523/41894.pdf LA English DT Article DE ;Crassostrea gigas;Alexandrium;Harmful algal blooms;Hemocyte;Microbial challenge AB The Pacific oyster Crassostrea gigas is an important commercial species cultured throughout the world. Oyster production practices often include transfers of animals into new environments that can be stressful, especially at young ages. This study was undertaken to determine if a toxic Alexandrium bloom, occurring repeatedly in French oyster beds, could modulate juvenile oyster cellular immune responses (i.e. hemocyte variables). We simulated planting on commercial beds by conducting a cohabitation exposure of juvenile, “specific pathogen-free” (SPF) oysters (naïve from the environment) with previously field-exposed oysters to induce interactions with new microorganisms. Indeed, toxic Alexandrium spp. exposures have been reported to modulate bivalve interaction with specific pathogens, as well as physiological and immunological variables in bivalves. In summary, SPF oysters were subjected to an artificial bloom of A. catenella, simultaneously with a cohabitation challenge. Exposure to A. catenella, and thus to the paralytic shellfish toxins (PSTs) and extracellular bioactive compounds produced by this alga, induced higher concentration, size, complexity and reactive oxygen species (ROS) production of circulating hemocytes. Challenge by cohabitation with field-exposed oysters also activated these hemocyte responses, suggesting a defense response to new microorganism exposure. These hemocyte responses to cohabitation challenge, however, were partially inhibited by A. catenella exposure, which enhanced hemocyte mortality, suggesting either detrimental effects of the interaction of both stressors on immune capacity, or the implementation of an alternative immune strategy through apoptosis. Indeed, no infection with specific pathogens (herpesvirus OsHV-1 or Vibrio aesturianus) was detected. Additionally, lower PST accumulation in challenged oysters suggests a physiological impairment through alteration of feeding-related processes. Overall, results of this study show that a short-term exposure to A. catenella combined with an exposure to a modified microbial community inhibited some hemocyte responses, and likely compromised physiological condition of the juvenile oysters. PY 2016 PD APR SO Fish & Shellfish Immunology SN 1050-4648 PU Academic Press Ltd- Elsevier Science Ltd VL 51 UT 000374617700013 BP 104 EP 115 DI 10.1016/j.fsi.2016.02.017 ID 42523 ER EF