Project description:Polar cod (Boreogadus saida), a key arctic fish species spawning during the polar night, may be at risk for crude oil exposure during this potential sensitive life stage. This study investigates the effects of crude oil exposure on Polar cod during spawning season. Wild-caught polar cod were exposed to crude oil water accommodated fraction (WAF) (start concentrations of sum of 44 polycyclic aromatic hydrocarbon (sum 44 PAHs) at 12.5 μg/L) from pre-spawning to post-spawning. The exposure system consisted of an oiled-rock-column system where running though sweater delivers WAF in the fish tank at decreasing concentrations over time. Samples were taken at three time-points (pre-spawning, spawning window, and post-spawning) and used to evaluate changes in reproductive endpoints such as gonad histology, plasma steroid hormones and sperm motility. For RNA-extraction and sequencing, liver samples from both oil-exposed and control groups of female fish (n = 5 per group) were taken at 47 days after experiment start and submitted for sequencing. RNA-seq analysis showed that hundreds of genes were differentially expressed in the liver.
Project description:This SuperSeries is composed of the following subset Series: GSE22171: Pacific salmon gill samples: fate tracking in river, sampled in ocean GSE22177: Pacific salmon gill samples: fate tracking in river GSE22347: Pacific salmon gill samples: fate tracking at spawning grounds Refer to individual Series
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 at the Weaver creek spawning grounds, and were observed for pre-spawning mortality or successful spawning.
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.
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.
Project description:A stable supply of viable eggs and embryos is crucial for successful farming of Atlantic cod. Broodstock stress can have negative effects, but little is known about the molecular mechanisms that cause abnormal development. Maternally transferred mRNAs have been shown to be essential for normal development, and stress may therefore influence their expression and the subsequent embryonic development. We investigated if mimicked stress in prespawning Atlantic cod females affects mRNA concentrations in eggs and embryos, and if this can be linked to egg/embryo viability, and if we could identify potential molecular markers for stress and egg/embryo viability. Consequently, 3 weeks prior to expected peak spawning, 20 females were intraperitoneally implanted with either cortisol-containing or cortisol-free (sham) osmotic pumps. At peak spawning all individuals were stripped and eggs were fertilized and incubated until hatching. Samples were collected from unfertilized eggs and embryos for gene expression profiling.
Project description:Pacific salmon undergo dramatic physiological remodeling during their terminal spawning migration, culminating in reproductive maturation, senescence, and death. To investigate the molecular mechanisms underlying these processes, we characterized transcriptomic changes in wild pink salmon (Oncorhynchus gorbuscha) sampled at three migratory stages (marine, riverine, and spawning ground) and across three tissues central to endocrine regulation and energy metabolism: gonads, head kidney, and skeletal muscle. RNA sequencing and dDifferential gene expression analyses waswere performed to identify biological pathways associated with maturation and semelparity. Transcriptomic changesremodeling wereas most pronounced during the final transition from river migrating fish entry to spawning, with the gonads exhibiting the greatest number of differentially expressed genes, followed by skeletal muscle and head kidney. Gene ontology analyses revealed coordinated upregulation of pathways associated with starvation responses, lipid mobilization, tissue catabolism, proteolysis, autophagy, and cell death across tissues. Immune and inflammatory processes were elevated in skeletal muscle and head kidney, while gonads showed strong enrichment of insulin signaling, steroid metabolism, and hormone-response pathways. Analysis of endocrine receptor expression identified tissue-specific and ohnolog-specific regulation of receptors involved in thyroid, growth hormone, insulin, gonadotropin, sex steroid, and glucocorticoid signaling, suggesting functional divergence among duplicated salmonid genes. These findings identified in pink salmon provide evidence that the demonstrate that the most extreme physiological changes occur extensive molecular reprogramming in pink salmon occurs duringat the time of final maturation rather than freshwater entry. The coordinated activation of endocrine, metabolic, and degenerative pathways supports a mechanistic link between reproductive development and semelparous senescence, providing new insight into the endocrine and transcriptomic networks that govern spawning-associated physiological decline in Pacific salmon.
Project description:This study investigates how parental exposure to the water-soluble fraction (WSF) of crude oil influences transcriptomic profiles in Atlantic cod (Gadus morhua) offspring. Fish were exposed to WSF for 20 days prior to spawning, and four offspring groups were generated by fertilization: control (unexposed parents), maternally exposed, paternally exposed, and biparentally exposed. Transcriptome analyses of embryos were performed at key developmental stages at 0, 2, 4 and 21 days post feralization (dpf) and the observed changes were correlated with phenotypic traits such as cardiac function and morphological measurements. Offspring groups from exposed females died before hatching. Transcriptome analyses indicated severe suppression or absence of expression of genes involved in early development in the maternally exposed groups. In contrast, paternal exposure had minimal impact on gene expression, and no phenotypic abnormalities were observed at hatching. Nonetheless, reduced survival in early larval stages suggested sublethal toxicity of crude oil.
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.