Hydrogen Sulfide as an Oxygen Sensor in Trout Chemoreceptors
Bibliographic record
Abstract
Oxygen (O 2 ) sensing chemoreceptors elicit cardiorespiratory reflexes in all vertebrates but the oxygen sensing‐signal transduction mechanism(s) is unknown. Here we examined the possibility that H 2 S is an O 2 sensor in rainbow trout where the first pair of gill arches is a primary site of chemoreception and the homolog of the mammalian carotid body. In unanesthetized trout, ambient hypoxia produced a PO 2 ‐dependent increase in plasma [H 2 S] indicative of inverse coupling of PO 2 and H 2 S. mRNA for the H 2 S synthesizing enzymes CBS and CSE was present in gill tissue and gills produced H 2 S enzymatically. Intrabuccal injection of H 2 S in unanesthetized trout produced a dose‐dependent bradycardia and increased ventilatory frequency and amplitude similar to hypoxia. Removal of the first but not second gill arches inhibited H 2 S‐mediated bradycardia, consistent with the hypothesized loss of aquatic chemoreceptor function. In isolated zebrafish neuroepithelial cells, the putative chemoreceptive cells of fish, hypoxia and H 2 S produced a similar ~10 mV depolarization. This suggests that H 2 S is involved in the O 2 sensing/signal transduction pathway in chemoreceptive cells as it is in vascular smooth muscle. This mechanism, whereby [H 2 S] is governed by the balance between constitutive production and oxidation, tightly couples tissue [H 2 S] to PO 2 and may provide an exquisitely sensitive O 2 sensor in a variety of tissues. Support: NSF IOS 0641436 & NSERC
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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".