Physiological and molecular mechanisms of osmoregulatory plasticity in killifish after seawater transfer
Bibliographic record
Abstract
We have explored the molecular and physiological responses of the euryhaline killifish Fundulus heteroclitus to transfer from brackish water (10% seawater) to 100% seawater for 12 h, 3 days or 7 days. Plasma [Na+] and [Cl-] were unchanged after transfer, and plasma cortisol underwent a transient increase. Na+/K+-ATPase activity increased 1.5-fold in the gills and opercular epithelium at 7 days (significant in gills only), responses that were preceded by three- to fourfold increases in Na+/K+-ATPase alpha(1a) mRNA expression. Expression of Na+/K+/2Cl- cotransporter 1, cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel, Na+/H+-exchanger 3 (significant in opercular epithelium only) and carbonic anhydrase II mRNA also increased two- to fourfold after transfer. Drinking rate increased over twofold after 12 h and remained elevated for at least 7 days. Surprisingly, net rates of water and ion absorption measured in vitro across isolated intestines decreased approximately 50%, possibly due to reduced salt demands from the diet in seawater, but water absorption capacity still exceeded the drinking rate. Changes in bulk water absorption were well correlated with net ion absorption, and indicated that slightly hyperosmotic solutions (>or=298 mmol l(-1)) were transported. There were no reductions in unidirectional influx of Na+ from luminal to serosal fluid or intestinal Na+/K+-ATPase activity after transfer. Overall, our results indicate that gill and opercular epithelia function similarly at a molecular level in seawater, in contrast to their divergent function in freshwater, and reveal unexpected changes in intestinal function. As such they provide further insight into the mechanisms of euryhalinity in killifish.
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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 | 0.001 |
| 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".