Integrated response of the zebrafish ( <i>Danio rerio</i> ) cardiovascular system to hypoxia acclimation
Bibliographic record
Abstract
Chronic hypoxia exposure of fish can cause remodelling of the gills as well as increases to haematocrit and haemoglobin binding affinity. There is less known, however, about how chronic hypoxia affects the structure and function of the heart. In the current study, zebrafish were exposed to moderate hypoxia for 7 weeks and then ultrasound was used to characterize cardiac function. We found that cardiac output of the hypoxia-acclimated fish was greater than that of the control fish during an acute hypoxia exposure. This difference was due, at least in part, to the higher cardiac stroke volume. Histological measurements demonstrated an increase in the cross-sectional area of the ventricle of hypoxia-exposed fish and this was supported by higher end diastolic area measurements made using ultrasound. These changes to the heart occurred in conjunction with an increase in haematocrit and the respiratory surface area of the gills, as well as an improved capacity of the fish to respond to a more severe acute hypoxia challenge. We also found an increase in the expression of the gene transcripts for hif-1αa and vegfaa at 24 h, 3 days and 8 days of hypoxia exposure, suggesting a rapid and consistent response. Our results suggest that, unlike normoxia-acclimated fish which demonstrate a decrease in cardiac output with acute hypoxia exposure, zebrafish acclimated to hypoxia maintain cardiac output when acutely exposed to hypoxia.
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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".