Reciprocal expression of gill Na+/K+-ATPaseα-subunit isoforms α1a and α1b during seawater acclimation of three salmonid fishes that vary in their salinity tolerance
Bibliographic record
Abstract
The upregulation of gill Na+/K+-ATPase activity is considered critical for the successful acclimation of salmonid fishes to seawater. The present study examines the mRNA expression of two recently discovered alpha-subunit isoforms of Na+/K+-ATPase (alpha1a and alpha1b) in gill during the seawater acclimation of three species of anadromous salmonids, which vary in their salinity tolerance. Levels of these Na+/K+-ATPase isoforms were compared with Na+/K+-ATPase activity and protein abundance and related to the seawater tolerance of each species. Atlantic salmon (Salmo salar) quickly regulated plasma Na+, Cl- and osmolality levels within 10 days of seawater exposure, whereas rainbow trout (Oncorhynchus mykiss) and Arctic char (Salvelinus alpinus) struggled to ionoregulate, and experienced greater perturbations in plasma ion levels for a longer period of time. In all three species, mRNA levels for the alpha1a isoform quickly decreased following seawater exposure whereas alpha1b levels increased significantly. All three species displayed similar increases in gill Na+/K+-ATPase activity during seawater acclimation, with levels rising after 10 and 30 days. Freshwater Atlantic salmon gill Na+/K+-ATPase activity and protein content was threefold higher than those of Arctic char and rainbow trout, which may explain their superior seawater tolerance. The role of the alpha1b isoform may be of particular importance during seawater acclimation of salmonid fishes. The reciprocal expression of Na+/K+-ATPase isoforms alpha1a and alpha1b during seawater acclimation suggests they may have different roles in the gills of freshwater and marine fishes; ion uptake in freshwater fish and ion secretion in marine fishes.
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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".