Cardiac mitochondrial metabolism may contribute to differences in thermal tolerance of red- and white-blooded Antarctic notothenioid fishes
Bibliographic record
Abstract
Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contributes to thermal tolerance. Here we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus, compared to the red-blooded Antarctic species, Notothenia coriiceps. Maximal activities of citrate synthase (CS) and lactate dehydrogenase (LDH), respiration rates of isolated mitochondria, adenylate levels, and changes in mitochondrial protein expression were quantified from hearts of animals held at ambient temperature or exposed to their critical thermal maximum (CTMAX). Compared to C. aceratus, activity of CS, ATP concentration, and energy charge were higher in hearts of N. coriiceps at ambient temperature and CTMAX. While state 3 mitochondrial respiration rates were not impaired by exposure to CTMAX in either species, state 4 rates, indicative of proton leakage, increased following exposure to CTMAX in C. aceratus but not N. coriiceps. The interactive effect of temperature and species resulted in an increase in antioxidants and aerobic metabolic enzymes in N. coriiceps, but not C. aceratus. Together, our results support the hypothesis that the lower aerobic metabolic capacity of C. aceratus hearts contributes to its low thermal tolerance.
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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".