Hypoxia acclimation alters reactive oxygen species homeostasis and oxidative status in estuarine killifish (<i>Fundulus heteroclitus</i>)
Bibliographic record
Abstract
Hypoxia is common in aquatic environments, and exposure to hypoxia followed by reoxygenation is often believed to induce oxidative stress. However, there have been relatively few studies of reactive oxygen species (ROS) homeostasis and oxidative status in fish that experience natural hypoxia-reoxygenation cycles. We examined how exposure to acute hypoxia (2 kPa O2) and subsequent reoxygenation (to 20 kPa O2) affects redox status, oxidative damage, and antioxidant defenses in estuarine killifish (Fundulus heteroclitus), and whether these effects were ameliorated or potentiated by prolonged (28 day) acclimation to either constant hypoxia or intermittent cycles of nocturnal hypoxia (12 h normoxia: 12 h hypoxia). Acute hypoxia and reoxygenation led to some modest and transient changes in redox status, increases in oxidized glutathione, depletion of scavenging capacity, and oxidative damage to lipids in the skeletal muscle. The liver had greater scavenging capacity, total glutathione concentrations, and activities of antioxidant enzymes (catalase, glutathione peroxidase) than the muscle, and generally experienced less variation in glutathiones and lipid peroxidation. Unexpectedly, acclimation to constant hypoxia or intermittent hypoxia led to a more oxidizing redox status (muscle and liver) and it increased oxidized glutathione (muscle). However, hypoxia acclimated fish exhibited little to no oxidative damage (as reflected by lipid peroxidation and aconitase activity), in association with improvements in scavenging capacity and catalase activity in muscle. We conclude that hypoxia acclimation leads to adjustments in ROS homeostasis and oxidative status that do not reflect oxidative stress but may instead be part of the suite of responses that killifish use to cope with chronic 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".