Osmoregulatory contributions of the corticotropin-releasing factor system in the intestine of Atlantic salmon
Bibliographic record
Abstract
The ability of euryhaline fishes to tolerate different environmental salinities depends upon the flexibility of their osmoregulatory organs, including the intestine. Several endocrine pathways contribute to the coordination of osmoregulatory processes in the teleost intestine; however, while the corticotropin-releasing factor (CRF) system has established osmoregulatory actions in the mammalian intestine, it is unclear whether the intestinal CRF system serves similar functions in teleosts. Therefore, we sought to determine whether the CRF system contributes to osmoregulatory processes in the intestine of Atlantic salmon (Salmo salar). We first showed using in vitro sac preparations that activation of CRF receptor type 2 (CRFR2) in the middle and posterior regions of the intestine reduces water, Na+ and Cl- absorption. However, co-activation of CRFR1 and CRFR2 inhibited water and Na+ absorption without affecting net Cl- absorption. We then assessed how the CRF system in the middle and posterior regions of the intestine was transcriptionally regulated during the seasonal acquisition of seawater tolerance (i.e. smoltification) and following changes in environmental salinity. Compared with parr, smolts had higher transcript levels of CRF ligands and this difference persisted following seawater transfer. Additionally, seawater transfer caused transient increases in transcription of urocortin 2 (ucn2) and crfr2 (posterior intestine only). Similar increases in ucn2 and crfr2 mRNA were observed following seawater to freshwater transfer of post-smolts. Our results indicate that the intestinal CRF system of Atlantic salmon contributes to osmoregulation during the initial days following changes in environmental salinity and that osmoregulatory actions of the intestinal CRF system are conserved across vertebrates.
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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".