ATP-induced reversed thermal sensitivity of O2 binding in both major hemoglobin polymorphs of the non-endothermic Atlantic cod, <i>Gadus morhua</i>
Bibliographic record
Abstract
Atlantic cod is a species affected by climate change with a major polymorphic hemoglobin component (HbI) whose two polymorphs show an inverse change in frequency along a latitudinal temperature cline in the North East Atlantic, and that have been associated with differences in performance and behavioural traits. An earlier study at the northern distribution limit of the species reported differential temperature sensitivities of red blood cell oxygen (O2) affinity between the northern cold-water HbI-2 polymorph and its southern, warm-water HbI-1 counter-part, which has since widely been held as adaptive for the species across its distributional range. The present study critically re-examined this hypothesis by comparing the thermal sensitivity of O2 binding in both purified HbI polymorphs from the southern, high temperature distribution limit of the species under controlled conditions of allosteric modifiers of Hb function. Contrary to the prevailing view the O2-affinity of the major HbI polymorphs did not differ from each other under any of the tested conditions. Depending on pH and ATP concentration, the temperature-sensitive and the temperature-insensitive Hb-O2 affinity phenotypes -previously exclusively ascribed to the HbI-1 and HbI-2, respectively- could be induced in both HbI polymorphs. These results are the first to establish a molecular mechanism behind a reversed temperature-dependence of red blood cell O2 affinity in an non-endotherm fish and lay the basis for future studies on alternative mechanisms behind the differences in distribution, performance, and behavioural traits associated with the different HbI polymorphs of Atlantic cod.
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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".