Transcriptome Profiling of Selectively Bred Pacific Oyster Crassostrea gigas Families that Differ in Tolerance of Heat Shock

Abstract

Sessile inhabitants of marine intertidal environments commonly face heat stress, an important component of summer mortality syndrome in the Pacific oyster Crassostrea gigas. Marker-aided selection programs would be useful for developing oyster strains that resist summer mortality; however, there is currently a need to identify candidate genes associated with stress tolerance and to develop molecular markers associated with those genes. To identify candidate genes for further study, we used cDNA microarrays to test the hypothesis that oyster families that had high (>64%) or low (<29%) survival of heat shock (43°C, 1 h) differ in their transcriptional responses to stress. Based upon data generated by the microarray and by real-time quantitative PCR, we found that transcription after heat shock increased for genes putatively encoding heat shock proteins and genes for proteins that synthesize lipids, protect against bacterial infection, and regulate spawning, whereas transcription decreased for genes for proteins that mobilize lipids and detoxify reactive oxygen species. RNAs putatively identified as heat shock protein 27, collagen, peroxinectin, S-crystallin, and two genes with no match in Genbank had higher transcript concentrations in low-surviving families than in high-surviving families, whereas concentration of putative cystatin B mRNA was greater in high-surviving families. These ESTs should be studied further for use in marker-aided selection programs. Low survival of heat shock could result from a complex interaction of cell damage, opportunistic infection, and metabolic exhaustion.

Comparative physiological, biochemical, and molecular thermal stress response profiles for two Unionid freshwater mussel species

“…Furthermore, correlating gene expression data with physiological and traditional life history parameters in response to chronic sub-lethal heat stress has become more prevalent. Such integrative approaches have been embraced across multiple disciplines and research interests, including freshwater (Doucet-Beaupré et al, 2010;Wang et al, 2012) and marine bivalves (Lang et al, 2009;Bettencourt et al, 2010;Clark et al, 2010;Craft et al, 2010;Fleury et al, 2010).…”

The environmentally tuned transcriptomes ofMytilusmussels

“…In a related study of population divergence, Pespeni et al (2013) correlated gene expression to growth under common-garden conditions between northern and southern sea urchin populations (S. purpuratus) and found that population-level differences in growth were underlined by the differential expression of genes involved in protein synthesis and biomineralization. In Pacific oysters (Crassostrea gigas), Lang et al (2009) showed that transcriptional responses to heat stress varied between selectively bred families in aquaculture, whereas Chaney and Gracey (2011) identified a set of genes whose differential expression was correlated with future mass mortality events. These studies illustrate the power and applicability of transcriptomics to a diverse array of study systems and research questions.…”

Characterization and Identification of Differentially Expressed Genes Involved in Thermal Adaptation of the Hong Kong Oyster Crassostrea hongkongensis by Digital Gene Expression Profiling

“…The seawater is static during the treatment with salinity at 20 ppt and pH at 7.2. Previous studies indicate that 1 h thermal exposure is stressful to this species (Lang et al, 2009). The control group was maintained in ambient seawater (23 • ± 2 • C) throughout the study.…”

“…We chose to study gill tissue as it is a large organ with high surface area exposed to the environment and has been shown to be perturbed by thermal stress (Lang et al, 2009). Total RNA was extracted from gill suspensions using 1 mL TRIzol Reagent (Invitrogen, Carlsbad, CA) per 100 mg of tissue following the manufacturer's instructions.…”

“…(Meistertzheim et al, 2007;Kawabe and Yokoyama, 2012;Zhang and Zhang, 2012;Li et al, 2015;Wang et al, 2015). Some other studies have utilized high-throughput techniques like microarray assay to estimate the expression profiles of hundreds of thousands of genes at the genome wide scale (Farcy et al, 2009;Lang et al, 2009). After heat shock, pacific oyster could immediately increase transcription of genes which encode heat shock proteins, and genes whose products synthesize lipids, participate in cellular immunity, and influence reproductive activity.…”