Induction of four glutamine synthetase genes in brain of rainbow trout in response to elevated environmental ammonia
Bibliographic record
Abstract
The key strategy for coping with elevated brain ammonia levels in vertebrates is the synthesis of glutamine from ammonia and glutamate, catalyzed by glutamine synthetase (GSase). We hypothesized that all four GSase isoforms (Onmy-GS01-GS04) are expressed in the brain of the ammonia-intolerant rainbow trout Oncorhynchus mykiss and that cerebral GSase is induced during ammonia stress. We measured GSase activity and the mRNA expression of Onmy-GS01-GS04 in fore-, mid- and hindbrain and liver, as well as ammonia concentrations in plasma, liver and brain of fish exposed to 9 or 48 h of 0 (control) or 670 micromol l(-1) NH(4)Cl (75% of the 96 h-LC(50) value). The mRNA of all four GSase isoforms were detected in brain (not liver). After 9 h of NH(4)Cl exposure, brain, liver and plasma ammonia content were elevated by two- to fourfold over control values. Midbrain, hindbrain and liver GSase activities were 1.3- to 1.5-fold higher in ammonia-exposed fish relative to control fish. Onmy-GS01-GS04 mRNA levels in brain (not liver) of ammonia-exposed fish (9 h) were significantly elevated by two- to fourfold over control values. After 48 h of the NH(4)Cl treatment, ammonia content and GSase activity, but not mRNA levels, in all tissues examined remained elevated compared to control fish. Taken together, these findings indicate that all four GSase isoforms are constitutively expressed in trout brain and are inducible under high external ammonia conditions. Moreover, elevation of GSase activities in fore-, mid- and hindbrain in response to environmental ammonia underlines the importance of brain GSase in the ammonia-stress response.
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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 | 0.001 | 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) | 0.000 | 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".