Control of Breathing in In Vitro Brain Stem Preparation from Goldfish (<i>Carassius auratus</i>; Linnaeus)
Bibliographic record
Abstract
In vitro brain stem preparations from goldfish (Carassius auratus) were used to first determine whether this species possesses central chemoreceptors able to modulate respiratory activity. Preparations were superfused with an artificial cerebrospinal fluid (aCSF); fictive breathing was recorded extracellularly by placing a suction electrode on cranial nerve VII. Reducing the level of O2 in the gas mixture used to bubble the aCSF from a hyperoxic level (80% or 98.7% O2) to a relative hypoxic level (20% or 40% O2) increased the frequency of the fictive respiratory burst (P = 0.0002). Reducing the pH of the aCSF from 7.9 to 7.4 by increasing CO2 in the superfusate did not affect fictive breathing. Chloride-mediated neurotransmission (GABA/glycine) is a major modulator of respiratory activity; however, its effect on the neural circuits that regulate breathing in teleosts remains unknown. Bath application of GABA (0.5, 5.0 mM) decreased burst frequency but not amplitude; this effect was dose dependent (drug × concentration: P = 0.01). Superfusion of the preparations with aCSF containing 1.25 μM of bicuculline methochloride and 1.50 μM of strychnine hydrochloride (GABAA and glycine receptor antagonists, respectively) increased burst frequency (P = 0.002) and amplitude (P < 0.001). We conclude that respiratory activity produced by the goldfish brain stem is not responsive to the moderate CO2 levels used in this study; it may contain O2 chemoreceptors, but the relatively small response could also reflect nonspecific effects of hypoxia on the central nervous system. Cl(-)-mediated neurotransmission inhibits fictive breathing; this aspect of respiratory regulation is similar to other groups of vertebrates.
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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".