Modulation of Rh glycoproteins, ammonia excretion and Na+ fluxes in three freshwater teleosts when exposed chronically to high environmental ammonia
Bibliographic record
Abstract
We investigated relationships among branchial unidirectional Na(+) fluxes, ammonia excretion, urea excretion, plasma ammonia, plasma cortisol, and gill transporter expression and function in three freshwater fish differing in their sensitivity to high environmental ammonia (HEA). The highly ammonia-sensitive salmonid Oncorhynchus mykiss (rainbow trout), the less ammonia-sensitive cyprinid Cyprinus carpio (common carp) and the highly ammonia-resistant cyprinid Carassius auratus (goldfish) were exposed chronically (12-168 h) to 1 mmol l(-1) ammonia (as NH4HCO3; pH 7.9). During HEA exposure, carp and goldfish elevated ammonia excretion (JAmm) and Na(+) influx rates ( ) while trout experienced higher plasma ammonia (TAmm) and were only able to restore control rates of JAmm and . All three species exhibited increases in Na(+) efflux rate ( ). At the molecular level, there was evidence for activation of a 'Na(+)/NH4(+) exchange metabolon' probably in response to elevated plasma cortisol and TAmm, though surprisingly, some compensatory responses preceded molecular responses in all three species. Expression of Rhbg, Rhcg (Rhcg-a and Rhcg-b), H(+)-ATPase (V-type, B-subunit) and Na(+)/K(+)-ATPase (NKA) mRNA was upregulated in goldfish, Rhcg-a and NKA in carp, and Rhcg2, NHE-2 (Na(+)/H(+) exchanger) and H(+)-ATPase in trout. Branchial H(+)-ATPase activity was elevated in goldfish and trout, and NKA activity in goldfish and carp, but NKA did not appear to function preferentially as a Na(+)/NH4(+)-ATPase in any species. Goldfish alone increased urea excretion rate during HEA, in concert with elevated urea transporter mRNA expression in gills. Overall, goldfish showed more effective compensatory responses towards HEA than carp, while trout were least effective.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".