Dataset Information


Salmon Spawning Migration: Metabolic Shifts and Environmental Triggers

ABSTRACT: A large-scale functional genomics study revealed shifting energy generating processes in white muscle during the final 1,300 km migration of wild sockeye salmon to their spawning grounds in the Fraser River, British Columbia. In 2006, Lower Adams stock sockeye salmon ceased feeding after passing the Queen Charlotte Islands, 850 km from the Fraser River. Enhanced protein turnover and reduced transcription of actin, muscle contractile and heme-related proteins were early starvation responses in saltwater. Arrival to the estuarine environment triggered massive protein turnover through induction of proteasoma and lysosomal proteolysis and protein biosynthesis, and a shift from anaerobic glycolysis to oxidative phosphorylation. Response to entry into freshwater was modest, with up-regulation of heat shock proteins and nitric oxide biosynthesis. High river temperatures resulted in a strong defense/immune response and high mortalities in 50% of fish. Arrival to the spawning grounds triggered further up-regulation of oxidative phosphorylation and proteolysis, down-regulation of protein biosynthesis and helicase activity, and continued down-regulation of muscle proteins and most glycolytic enzymes. However, sharp up-regulation of PFK-I indicated induction of glycolytic potential at the spawning grounds. The identification of potential environmental cues triggering genome-wide transcriptional shifts in white muscle associated with migration and the strong activation of proteasomal proteolysis were both novel findings. Keywords: Functional genomics study on wild-caught fish Overall design: The experiment was based on expression profiles of white muscle tissue collected from wild migrating adult sockeye salmon during their return spawning migration back to the Fraser River. Fish were collected from seven sites along the final 1,300 km migration path, and white muscle samples were quickly frozen in liquid nitrogen upon capture. Marine sampling sites included (from north to south) the Queen Charlotte Islands (QCI), Johnstone Strait (JS), Juan de Fuca Strait (JDFS), and the Strait of Georgia (SOG). Freshwater sampling sites included Whonnock (W), Savona (SV) and the Lower Adams Spawning Grounds. Genetically-based stock ID was used to identify the natal sites of fish collected from the wild. The experiment was designed to profile the transcriptional shifts associated with migration of the Adams River stock complex. The total experiment included 80 microarray slides, with a minimum biological replicate size per site of 6 (SV), and maximum of 18 (JS) (see supplemental table for details). Additional intra-site variables, which could only be addressed in some sites, included sex (female biased) and river entry timing (for JS, JDFS and W sites; identified through radio-tracking of marine collected fish). 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 experiment was based on a reference design, with the reference containing the combined aRNA of all individuals used in the experiment. Individual samples were labelled with Alexa 555 and the reference control with Alexa 647, with no dye flips included. A single technical replicate of one SV fish (replicate 5) was included in the experimental design. This experiment is part of a larger white muscle experiment containing additional sockeye salmon stocks.

INSTRUMENT(S): GRASP salmonid array, 16k v2.0 chip, updated data files 15 July 2005

ORGANISM(S): Oncorhynchus nerka  

SUBMITTER: Shaorong Li  

PROVIDER: GSE13657 | GEO | 2008-12-09



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