Differential Gene Expression in Liver, Gill, and Olfactory Rosettes of Coho Salmon (Oncorhynchus kisutch) After Acclimation to Salinity

Abstract

Most Pacific salmonids undergo smoltification and transition from freshwater to saltwater, making various adjustments in metabolism, catabolism, osmotic, and ion regulation. The molecular mechanisms underlying this transition are largely unknown. In the present study, we acclimated coho salmon (Oncorhynchus kisutch) to four different salinities and assessed gene expression through microarray analysis of gills, liver, and olfactory rosettes. Gills are involved in osmotic regulation, liver plays a role in energetics, and olfactory rosettes are involved in behavior. Between all salinity treatments, liver had the highest number of differentially expressed genes at 1616, gills had 1074, and olfactory rosettes had 924, using a 1.5-fold cutoff and a false discovery rate of 0.5. Higher responsiveness of liver to metabolic changes after salinity acclimation to provide energy for other osmoregulatory tissues such as the gills may explain the differences in number of differentially expressed genes. Differentially expressed genes were tissue- and salinity-dependent. There were no known genes differentially expressed that were common to all salinity treatments and all tissues. Gene ontology term analysis revealed biological processes, molecular functions, and cellular components that were significantly affected by salinity, a majority of which were tissue-dependent. For liver, oxygen binding and transport terms were highlighted. For gills, muscle, and cytoskeleton-related terms predominated and for olfactory rosettes, immune response-related genes were accentuated. Interaction networks were examined in combination with GO terms and determined similarities between tissues for potential osmosensors, signal transduction cascades, and transcription factors.

Phenotypic and molecular consequences of stepwise temperature increase across generations in a coral reef fish

“…This gene represents an essential checkpoint in the G2 phase of mitosis, being able to inhibit the genomic instabilities associated with tumours (Hollander & Fornace, ). Upregulation of this gene has been reported in individuals subject to chemical (turbot; Ruiz, Orbea, Rotchell, & Cajaraville, ) and osmotic stress (salmon; Maryoung et al., ) for extended periods of time. It is possible that this DNA repair gene is acting as a regulator of cell proliferation in Step +3.0°C after gradual temperature increase across generations.…”

Elevated CO2 impairs olfactory‐mediated neural and behavioral responses and gene expression in ocean‐phase coho salmon (Oncorhynchus kisutch)

“…While future oceanic CO 2 concentrations may not reach such high steady‐state levels, exposures to transient CO 2 concentrations at these levels may already occur in some regions and will likely be more common. Juvenile coho salmon spend up to a year rearing in freshwater (Quinn, ) before migrating downstream to the ocean, undergoing the physiological transformation of smoltification that prepares them for life in seawater, including changes in osmoregulation and ion balance regulation (Maryoung et al, ; McCormick, ; Quinn, ). Our results suggest that despite having an adaptable olfactory system that functions in both marine and freshwater environments with very different pHs and water chemistries, the relative sensitivity of these anadromous fish to elevated CO 2 in the ocean is similar to other marine fish.…”

“…While future oceanic CO 2 concentrations may not reach such high steady-state levels, exposures to transient CO 2 concentrations at these levels may already occur in some regions and will likely be more common. Juvenile coho salmon spend up to a year rearing in freshwater (Quinn, 2011) before migrating downstream to the ocean, undergoing the physiological transformation of smoltification that prepares them for life in seawater, including changes in osmoregulation and ion balance regulation (Maryoung et al, 2015;McCormick, 2012;Quinn, 2011).…”

Variation in juvenile Chinook salmon (Oncorhynchus tshawytscha) transcription profiles among and within eight population crosses from British Columbia, Canada

“…Here we use Chinook salmon as a model system to explore within‐ and among‐population variation in gene transcription in the liver for 22 known‐function gene loci, spanning immune, growth, metabolic, and stress‐related functions. We selected liver as our target tissue because it has been shown to exhibit differentiation in gene expression for many genes across salmonid species (Maryoung et al, ; Škugor, Jørgensen, Gjerde, & Krasnov, ). We used a hierarchical breeding design to test for population differences in gene transcription at the 22 selected loci across eight half‐sibling population crosses.…”