Project description:Summer mortality of the Pacific oyster Crassostrea gigas is the result of a complex interaction between oysters, their environment and pathogens. Heredity appears to be a major factor determining the sensitivity of oysters to summer mortality, allowing resistant (R) and susceptible (S) lines to be produced. We conducted genome-wide expression profiling of R and S gonads during the 3-month period preceding a summer mortality event using a 9K cDNA microarray that we designed. This transcriptional analysis provides new indications to define markers for Quantitative Trait Loci searches and functional studies, and evaluates the potential role of each gene in the resistance to summer mortality
Project description:The Pacific oyster (Crassostrea gigas) is a kind of marine bivalve of great economic and ecological importance and is among the animals possessing the highest level of genome DNA variations. Despite large efforts made for the discovery of Pacific oyster SNPs in many research groups, challenge still remains as how to utilize SNPs in a high-throughput, transferable and economical manner. In the study, we constructed an oyster 190K SNP array with Affymetrix Axiom genotyping technology. A total of 190,420 SNPs were designed on the chip, which were selected from 54 M SNPs identified by re-sequencing of more than 400 Pacific oysters. Genotyping results from 96 wild oysters indicated that 133,984 (70.4%) SNPs were polymorphic and successfully converted on the chip. Carrying 133K polymorphic SNPs, the oyster 190K SNP array is the first high density SNP chip with the largest throughput currently in mollusc and is commercially available to the worldwide research community.
Project description:Pacific oysters (Crassostrea gigas) were exposed to either 400 µatm (control) or 2800 µatm (ocean acidification) of pCO2 for 1 month. At the end of 1 month, half of the oysters from each pCO2 treatment were subjected to an additional mechanical stimulation. Gill (ctenidia) tissue was excised from 4 oysters from each of 4 treatments - 400 and 2800 µatm with and without mechanical stimulation. Tandem mass spectrometry was performed on all 16 samples on a LTQ Orbitrap XL with 3 technical replicates per biological sample.
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:To elucidate the modulatory participation of miRNAs in mollusk biomineralization, we have employed high-throughput sequencing to identify miRNAs of pearl oyster, Pinctada fucata. Our study focused on the miRNA expression profile of the mantle, an organ responsible for shell formation of the oyster. The pearl oysters were cultured in the tank with the maintaining conditions of temperature 19 ℃, PH 8.1 and salinity 33‰ in recirculating seawater.
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.
Project description:Low salinity is one of the main factors limiting the distribution and survival of marine species. As a euryhaline species, the Pacific oyster Crassostrea gigas can be tolerant to relative low salinity. Through Illumina sequencing, we generated two transcriptomes with samples taken from gills of oysters exposed to the low salinity seawater versus the optimal seawater. By RNAseq technology, we found 1665 up-regulation genes and 1815 down-regulation genes that may regulate osmotic stress in C. gigas. As blasted by GO annotation and KEGG pathway mapping, functional annotation of the genes recovered diverse biological functions and processes. The genes regulated significantly were dominated in cellular process and regulation of biological process, intracellular and cell, binding and protein binding according to GO annotation. The results highlight genes related to osmoregulation and signaling and interactions of osmotic stress response, anti-apoptotic reactions as well as immune response, cell adhesion and communication, cytosqueleton and cell cycle. The study aimed to compare the expression data of the two transcriptomes to provide some useful insights into signal transduction pathways in oysters and offer a number of candidate genes as potential markers of tolerance to hypoosmotic stress for oysters. In addition, the characterization of C. gigas transcriptome will facilitate research into biological processes underlying physiological adaptations to hypoosmotic shock for marine invertebrates. Twelve Pacific oysters were exposed in low salinity (8‰) seawater and in optimal salinity (25‰) seawater, respectively. Gills from six oysters in each condition were balanced mixed respectively. The transcriptomes of two samples were generated by deep sequencing, using Illumina HiSeq2000.