title: Immune and stress responses in oysters with insights on adaptation.
abstract: Oysters are representative bivalve molluscs that are widely distributed in world oceans. As successful colonizers of estuaries and intertidal zones, oysters are remarkably resilient against harsh environmental conditions including wide fluctuations in temperature and salinity as well as prolonged air exposure. Oysters have no adaptive immunity but can thrive in microbe-rich estuaries as filter-feeders. These unique adaptations make oysters interesting models to study the evolution of host-defense systems. Recent advances in genomic studies including sequencing of the oyster genome have provided insights into oyster's immune and stress responses underlying their amazing resilience. Studies show that the oyster genomes are highly polymorphic and complex, which may be key to their resilience. The oyster genome has a large gene repertoire that is enriched for immune and stress response genes. Thousands of genes are involved in oyster's immune and stress responses, through complex interactions, with many gene families expanded showing high sequence, structural and functional diversity. The high diversity of immune receptors and effectors may provide oysters with enhanced specificity in immune recognition and response to cope with diverse pathogens in the absence of adaptive immunity. Some members of expanded immune gene families have diverged to function at different temperatures and salinities or assumed new roles in abiotic stress response. Most canonical innate immunity pathways are conserved in oysters and supported by a large number of diverse and often novel genes. The great diversity in immune and stress response genes exhibited by expanded gene families as well as high sequence and structural polymorphisms may be central to oyster's adaptation to highly stressful and widely changing environments.
authors.affiliation: Haskin Shellfish Research Laboratory, Department of Marine and Coastal Sciences, Rutgers University, Port Norris, NJ 08345, USA. Electronic address: xguo@hsrl.rutgers.edu.
authors.forename: Ximing
authors.initials: X
authors.lastname: Guo
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong 266003, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Linlin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: UMR BOREA, "Biologie des Organismes et Ecosystèmes Aquatiques", MNHN, UPMC, UCBN, CNRS-7208, IRD, Université de Caen Basse-Normandie, Esplanade de la Paix, 14032 Caen, France; Centre de Référence sur l'Huître (CRH), Université de Caen Basse Normandie, Esplanade de la Paix, 14032 Caen, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Lelong
authors.affiliation: UMR BOREA, "Biologie des Organismes et Ecosystèmes Aquatiques", MNHN, UPMC, UCBN, CNRS-7208, IRD, Université de Caen Basse-Normandie, Esplanade de la Paix, 14032 Caen, France; Centre de Référence sur l'Huître (CRH), Université de Caen Basse Normandie, Esplanade de la Paix, 14032 Caen, France.
authors.forename: Aude
authors.initials: A
authors.lastname: Jouaux
mesh_terms: D000220:Adaptation, Biological / Q000276:immunology*; D000818:Animals; D016678:Genome; D007113:Immunity, Innate; D010125:Ostreidae / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D013312:Stress, Physiological
keywords: Adaptation; Environmental stress; Gene expansion and diversity; Immune response genes; Innate immunity; Mollusc; OsHV-1; Oysters