The Transcriptomic Responses of Atlantic Salmon (Salmo salar) to High Temperature Stress Alone, and in Combination with Moderate Hypoxia
Bibliographic record
Abstract
Abstract Background: Increases in seawater temperatures and in the frequency and severity of hypoxic events are expected with climate change, and may become a challenge for cultured Atlantic salmon and negatively affect their growth, immunology and welfare. Thus, we examined how an incremental temperature increase alone (Warm & Normoxic-WN: 12→20°C; 1°C week-1), and in combination with moderate hypoxia (Warm & Hypoxic-WH: ~70% air saturation), impacted salmon’s hepatic transcriptome expression compared to control fish (CT: 12°C, normoxic) using 44K microarrays and qPCR. Results: Overall, we identified 2,894 differentially expressed probes (DEPs, FDR < 5%), that included 1,111 shared DEPs, while 789 and 994 DEPs were specific to WN and WH fish, respectively. Pathway analysis suggested that the cellular mechanisms affected by the two experimental conditions were quite similar, with up-regulated genes functionally associated with heat shock response, ER-stress, apoptosis and immune defence, while genes connected with general metabolic processes, proteolysis and oxidation-reduction were largely suppressed. The qPCR assessment of 41 microarray-identified genes validated that the heat shock response (hsp90aa1, serpinh1), apoptosis (casp8, jund, jak2) and immune responses (apod, c1ql2, epx) were up-regulated in WN and WH fish, while oxidative stress and hypoxia sensitive genes were down-regulated (cirbp, cyp1a1, egln2, gstt1, hif1α, prdx6, rraga, ucp2). However, the additional challenge of hypoxia resulted in more pronounced effects on heat shock and immune-related processes, including a stronger influence on the expression of 14 immune-related genes. Finally, robust correlations between the transcription of 19 genes and several phenotypic traits in WH fish suggest that changes in gene expression were related to an impaired physiological and growth performance. Conclusion: Increasing temperature to 20°C alone, and in combination with hypoxia, resulted in the up- and down-regulation of genes involved in similar important pathways in Atlantic salmon. However, the heat shock and immune responses of fish exposed to 20°C and hypoxia were more affected, and their transcriptional dysregulation was related to reduced performance. This study provides valuable information on how these two environmental challenges affect the expression of stress-, metabolic- and immune-related genes and pathways and identifies potential biomarker genes for improving our understanding of fish health and welfare.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".