Dataset Information

Consequences of high temperatures and premature mortality on the transcriptome and blood physiology of wild adult sockeye salmon (Oncorhynchus nerka)

ABSTRACT: We collected sockeye salmon from the Fraser River, British Columbia, and held them at ecologically relevant temperatures (14C and 19C) determine the effect of elevated water temperature on cellular processes in non-lethally sampled gill tissue and blood plasma over a period of seven days that represents a significant portion of their upstream migration. Time-matched fish that died prematurely over the course of the holding study were also sampled for gill tissue and the transcriptomic responses in moribund fish were compared with surviving fish. This is the first study to experimentally examine transcriptomic responses to high water temperature and premature mortality in wild-caught Pacific salmon and the results will help in understanding some of the cellular mechanisms involved in large-scale migration mortality in Pacific salmon during warm water periods and for predicting or understanding causes of mortality in naturally senescing adult Pacific salmon.

ORGANISM(S): Salmo salar Oncorhynchus tshawytscha Osmerus mordax Coregonus clupeaformis Oncorhynchus mykiss Oncorhynchus nerka

PROVIDER: GSE33586 | GEO | 2012/05/31

SECONDARY ACCESSION(S): PRJNA148551

REPOSITORIES: GEO

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Project description:a salmonid microarray was used to characterize environmentally-regulated shifts in gene expression between ocean and river habitats in gill and liver tissues of wild migrating adult Pacific sockeye salmon (Oncorhynchus nerka). To correlate gene expression with survival, non-lethal biopsy sampling of gill tissue and microarray-based profiling was combined with biotelemetry and genetic stock identification so that transcriptomic profiles could be compared between fish reaching spawning grounds and presumed mortalities. Fish were captured fish at two marine sampling sites, one within Johnstone Strait (JS), BC. Canada and one within Juan De Fuca Strait (JDFS), BC Canada. Ocean sites were contrasted to fish sampled within the Fraser River at Whonnock (W), BC, Canada. Gill and liver tissues were dissected at each of these sites. Non-lethal biopsy sampling was performed on migrating sockeye salmon intercepted within the Fraser River at Mission, BC, Canada and genetically-based stock ID was used to determine the stock-specific spawning grounds for each fish, giving an intended end-point of migration for each of the stocks investigated in this study.Gene expression levels were determined by comparing the amount of mRNA transcript in the experimental samples relative to a reference sample. A total of 123 microarrays were used to generate the dataset, corresponding to individual hybridizations of both gill and liver samples collected from JS (gill n=14; liver n=15), JDFS (gill n=15; liver n=13), W (gill n=11; liver n=10), and biopsy sampled gill tissue collected at Mission (n=45).Total RNA was amplified (1 round) with MessageAmpTMII-96 kit (Ambion, TX, USA), and reverse transcribed to cDNA before labelling with ALEXA dyes using the Invitrogen Indirect Labelling Kit. The reference contained the combined aRNA of all individuals used in the experiment, excluding bioposy sampled fish. Individual samples were labelled with Alexa 555 and the reference control with Alexa 647, and no dye swaps were perfromed.

Project description:The long-term viability of Pacific salmon stocks and the fisheries they support are threatened if large numbers die prematurely en-route to spawning grounds. Physiological profiles that were correlated with the fate of wild sockeye salmon during river migration were discovered using functional genomics studies on biopsied tissues. Three independent biotelemetry studies tracked the biopsied fish after tagging in the marine environment over 200 km from the Fraser River, in the lower river 69 km from the river mouth and at the spawning grounds. Salmon carrying the poor performance (unhealthy) profile in the ocean exhibited a 4-times lower probability of arriving to spawning grounds than those with a healthy genomic signature, although generally migrated into the river and to the spawning grounds faster. A related unhealthy signature observed in the river was associated with a 30% reduction in survival to spawning grounds in one of the three stocks tested. At spawning grounds, the same poor performance signature was associated with twice the pre-spawning mortality compared with healthy fish. Functional analysis revealed that the unhealthy signature, which intensified during migration to spawning grounds, was consistent with an intracellular pathogenic infection, likely a virus. These results are the first to suggest a pathogen present in salmon in the marine environment could be a major source of mortality during migration and spawning in the river. This series are gill expression profiles from the study of fish sampled and tagged in the lower river and tracked as they swam towards the spawning grounds. Fish were caught in seine nets, gastrically implanted with radio transmitters, and biopsy sampled for blood, gill, muscle, and fin. Individual fish were tracked by receivers placed throughout the Fraser River watershed to identify and fate (i.e. the location of the receiver that last detected the fish). Targeted stocks of interest were genetically identified. Gene expression was profiled in gill tissue, a critical respiratory and ionoregulatory organ that is highly responsive to stress, chemical exposure and disease. Gene expression was assayed on the GRASP salmonid 16K cDNA microarray.

Project description:The long-term viability of Pacific salmon stocks and the fisheries they support are threatened if large numbers die prematurely en-route to spawning grounds. Physiological profiles that were correlated with the fate of wild sockeye salmon during river migration were discovered using functional genomics studies on biopsied tissues. Three independent biotelemetry studies tracked the biopsied fish after tagging in the marine environment over 200 km from the Fraser River, in the lower river 69 km from the river mouth and at the spawning grounds. Salmon carrying the poor performance (unhealthy) profile in the ocean exhibited a 4-times lower probability of arriving to spawning grounds than those with a healthy genomic signature, although generally migrated into the river and to the spawning grounds faster. A related unhealthy signature observed in the river was associated with a 30% reduction in survival to spawning grounds in one of the three stocks tested. At spawning grounds, the same poor performance signature was associated with twice the pre-spawning mortality compared with healthy fish. Functional analysis revealed that the unhealthy signature, which intensified during migration to spawning grounds, was consistent with an intracellular pathogenic infection, likely a virus. These results are the first to suggest a pathogen present in salmon in the marine environment could be a major source of mortality during migration and spawning in the river. This series is of gill expression profiles from the study of fish sampled and tagged in the ocean and tracked as they entered the river system and swam towards the spawning grounds. Fish were caught in seine nets, gastrically implanted with radio transmitters, and biopsy sampled for blood, gill, muscle, and fin. Individual fish were tracked by receivers placed throughout the Fraser River watershed to identify and fate (i.e. the location of the receiver that last detected the fish). Targeted stocks of interest were genetically identified. Gene expression was profiled in gill tissue, a critical respiratory and ionoregulatory organ that is highly responsive to stress, chemical exposure and disease. Gene expression was assayed on the GRASP salmonid 16K cDNA microarray.

Dataset Information

Consequences of high temperatures and premature mortality on the transcriptome and blood physiology of wild adult sockeye salmon (Oncorhynchus nerka)

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