Transcriptional Response to Acute Thermal Exposure in Juvenile Chinook Salmon Determined by RNAseq

Abstract

Thermal exposure is a serious and growing challenge facing fish species worldwide. Chinook salmon (Oncorhynchus tshawytscha) living in the southern portion of their native range are particularly likely to encounter warmer water due to a confluence of factors. River alterations have increased the likelihood that juveniles will be exposed to warm water temperatures during their freshwater life stage, which can negatively impact survival, growth, and development and pose a threat to dwindling salmon populations. To better understand how acute thermal exposure affects the biology of salmon, we performed a transcriptional analysis of gill tissue from Chinook salmon juveniles reared at 12° and exposed acutely to water temperatures ranging from ideal to potentially lethal (12° to 25°). Reverse-transcribed RNA libraries were sequenced on the Illumina HiSeq2000 platform and a de novo reference transcriptome was created. Differentially expressed transcripts were annotated using Blast2GO and relevant gene clusters were identified. In addition to a high degree of downregulation of a wide range of genes, we found upregulation of genes involved in protein folding/rescue, protein degradation, cell death, oxidative stress, metabolism, inflammation/immunity, transcription/translation, ion transport, cell cycle/growth, cell signaling, cellular trafficking, and structure/cytoskeleton. These results demonstrate the complex multi-modal cellular response to thermal stress in juvenile salmon.

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

“…Results from our pathway analysis are consistent with this mechanism of misfolded protein removal under thermal stress. Corresponding with our results, previous reports in Oncorhynchus tshawytscha and Stylophora pistillata suggest that the genes involved in protein processing in endoplasmic reticulum are significantly up-regulated under heat stress (Maor-Landaw et al, 2014;Tomalty et al, 2015). Thus, our transcriptomic study indicated that protein processing in endoplasmic reticulum may be involved in thermal stress response in the Hong Kong oysters which are vital for survival of the organism in such unfavorable conditions.…”

An integrated linkage map reveals candidate genes underlying adaptive variation in Chinook salmon (Oncorhynchus tshawytscha)

“…The three thermotolerance QTL that explained the greatest percentage of phenotypic variation were found to contain a gene previously associated with thermotolerance in Chinook salmon as well as other species (HSP70) (Narum & Campbell ; Tomalty et al . ) and its inhibitor (BAG) (Takayama et al . ), as well as a gene recently shown to be involved in the MAPK signalling pathway which is involved in thermotolerance (ZNF416) (Dorion & Landry ; Van Rossom et al .…”

The utility of transcriptomics in fish conservation

“…High water temperature can alter expression of genes involved in extracellular matrix and cytoskeleton restructuring, and collagen stabilization in fishes (Jeffries et al, 2012a;Liu et al, 2013;Tomalty et al, 2015), processes that are critical during skeletal growth (Vieira et al, 2013) and were impacted in the present study. Because the larval stages of development in fishes are plastic, temperature impacts during early life stages may lead to long-term effects on growth (Johnston, 2006).…”