Exposure to the toxic dinoflagellate Alexandrium catenella modulates juvenile oyster Crassostrea gigas hemocyte variables subjected to different biotic conditions

Type Article
Date 2016-04
Language English
Author(s) Lassudrie MalwennORCID1, Soudant Philippe1, Nicolas Jean-Louis2, Miner Philippe2, Le Grand Jacqueline2, Lambert Christophe1, Le Goic Nelly1, Hegaret HeleneORCID1, Fabioux Caroline1
Affiliation(s) 1 : 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.
2 : IFREMER, Lab Sci Environm Marin LEMAR, UMR 6539, CNRS,UBO,IRD,Lab Physiol Invertebres, Technopole Brest Iroise BP 70, F-29280 Plouzane, France.
Source Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2016-04 , Vol. 51 , P. 104-115
DOI 10.1016/j.fsi.2016.02.017
WOS© Times Cited 8
Keyword(s) Crassostrea gigas, Alexandrium, Harmful algal blooms, Hemocyte, Microbial challenge
Abstract 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.
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Lassudrie Malwenn, Soudant Philippe, Nicolas Jean-Louis, Miner Philippe, Le Grand Jacqueline, Lambert Christophe, Le Goic Nelly, Hegaret Helene, Fabioux Caroline (2016). Exposure to the toxic dinoflagellate Alexandrium catenella modulates juvenile oyster Crassostrea gigas hemocyte variables subjected to different biotic conditions. Fish & Shellfish Immunology, 51, 104-115. Publisher's official version : https://doi.org/10.1016/j.fsi.2016.02.017 , Open Access version : https://archimer.ifremer.fr/doc/00314/42523/