Project description:Deep sequencing of samples from different development stages, different adult organs and different stress treatments of Pacific oyster Crassostrea gigas
Project description:Deep sequencing of mRNA from Pacific oyster Crassostrea gigas Competent larvae of Crassostrea gigas were treated with epinephrine solution, and then sampled at different time intervals. For shell damage experiment, shell were broken and then tissues were sampled at different time intervals.
Project description:The cultivated Pacific oyster Crassostrea gigas has suffered for decades large scale summer mortality phenomenon resulting from the interaction between the environment parameters, the oyster physiological and/or genetic status and the presence of pathogenic microorganisms including Vibrio species. To obtain a general picture of the molecular mechanisms implicated in C. gigas immune responsiveness to circumvent Vibrio infections, we have developed the first deep sequencing study of the transcriptome of hemocytes, the immunocompetent cells. Using Digital Gene Expression (DGE), we generated a transcript catalog of up-regulated genes from oysters surviving infection with virulent Vibrio strains (Vibrio splendidus LGP32 and V. aestuarianus LPi 02/41) compared to an avirulent one, V. tasmaniensis LMG 20012(T). For that an original experimental infection protocol was developed in which only animals that were able to survive infections were considered for the DGE approach. We report the identification of cellular and immune functions that characterize the oyster capability to survive pathogenic Vibrio infections. Functional annotations highlight genes related to signal transduction of immune response, cell adhesion and communication as well as cellular processes and defence mechanisms of phagocytosis, actin cytosqueleton reorganization, cell trafficking and autophagy, but also antioxidant and anti-apoptotic reactions. In addition, quantitative PCR analysis reveals the first identification of pathogen-specific signatures in oyster gene regulation, which opens the way for in depth molecular studies of oyster-pathogen interaction and pathogenesis. This work is a prerequisite for the identification of those physiological traits controlling oyster capacity to survive a Vibrio infection and, subsequently, for a better understanding of the phenomenon of summer mortality.
Project description:Ostreid Herpesvirus type 1 (OsHV-1) has become a serious infective agent of the Pacific oyster livestock worldwide. In particular, the OsHV-1 muVar subtype has been associated to severe mortality episodes concerning Crassostrea gigas in France and other regions of the world such as Australia and New Zealand. Factors triggering productive infections and virus interactions with susceptible and resistant bivalve hosts are not completely understood though some studies have been undertaken to explore the genes expressed in oysters after infection. We took advantage of an highly infected oyster sample to perform an in-vivo dual RNA-seq analysis. An extremely high sequencing coverage allowed us to explore in detail the Herpesvirus genome and transcriptome, and to identify viral-activated molecular pathways in Crassostrea gigas, thus expanding the current knowledge on the host-virus interactions.
Project description:Marine intertidal organisms commonly face hypoxic stress during low tide emersion; moreover, eutrophic conditions and sediment nearness could lead to hypoxic phenomena; it is indeed important to understand the molecular processes involved in the response to hypoxia. In this study the molecular response of the Pacific oyster Crassostrea gigas to prolonged hypoxia (2 mg O2 L-1 for 20 d) was investigated under experimental conditions. A transcriptomic approach was employed using a cDNA microarray of 9058 C. gigas clones to highlight the genetic expression patterns of the Pacific oyster under hypoxic conditions. Lines of oysters resistant (R) and susceptible (S) to summer mortality were used in this study. This is the first study employing microarrays to characterize the genetic markers and metabolic pathways responding to hypoxic stress in C. gigas.
Project description:The cultivated Pacific oyster Crassostrea gigas has suffered for decades large scale summer mortality phenomenon resulting from the interaction between the environment parameters, the oyster physiological and/or genetic status and the presence of pathogenic microorganisms including Vibrio species. To obtain a general picture of the molecular mechanisms implicated in C. gigas immune responsiveness to circumvent Vibrio infections, we have developed the first deep sequencing study of the transcriptome of hemocytes, the immunocompetent cells. Using Digital Gene Expression (DGE), we generated a transcript catalog of up-regulated genes from oysters surviving infection with virulent Vibrio strains (Vibrio splendidus LGP32 and V. aestuarianus LPi 02/41) compared to an avirulent one, V. tasmaniensis LMG 20012(T). For that an original experimental infection protocol was developed in which only animals that were able to survive infections were considered for the DGE approach. We report the identification of cellular and immune functions that characterize the oyster capability to survive pathogenic Vibrio infections. Functional annotations highlight genes related to signal transduction of immune response, cell adhesion and communication as well as cellular processes and defence mechanisms of phagocytosis, actin cytosqueleton reorganization, cell trafficking and autophagy, but also antioxidant and anti-apoptotic reactions. In addition, quantitative PCR analysis reveals the first identification of pathogen-specific signatures in oyster gene regulation, which opens the way for in depth molecular studies of oyster-pathogen interaction and pathogenesis. This work is a prerequisite for the identification of those physiological traits controlling oyster capacity to survive a Vibrio infection and, subsequently, for a better understanding of the phenomenon of summer mortality. 4 Samples.
Project description:miRNA sequencing of Pacific oyster Crassostrea gigas for different organs and developmental stages. Two RNA pools were created and sequenced by mixing the samples before and after the developmental stage "D shaped larvae". Then ten developmental samples and eleven samples from 7 organs were sequenced.
Project description:To assess the diurnal gene expression in gills of oyster Crassotrea gigas, gills of 6 oysters were pooled and analyzed by RNa-seq every 4h for 52h (i.e. 13 sampling times). This procedure was executed simultaneously for control oysters fed with the non-harmful algae Heterocapsa triquetra (H.t condition), and for oysters fed with the harmful algae Alexandrium minutum (A.m condition) (L:D 9:15). Alexandrium minutum exposure led to a remodeling of the cycling transcriptome in gills of Crassostrea gigas.