Comparative physiology of hypoxia tolerance in intertidal sculpins
Bibliographic record
Abstract
The goal of our work is to characterize the underlying factors that result in variation in hypoxia tolerance among organisms. At that heart of hypoxia tolerance is the ability to effectively acquire and utilized environmental oxygen at the mitochondria to sustain aerobic function even when exposed to oxygen limitations. In order to elucidate the factors that explains variation in hypoxia tolerance among organisms, we use a well‐described, phylogenetically informed comparative system involving several species of marine fish from the family Cottidae (sculpins) that show a strong habitat zonation along the near‐shore environment. Sculpins from the intertidal zone experience daily fluctuations in O 2 with species located in the higher intertidal oscillating between ~0 to 400% air saturation and are hypoxia tolerant, whereas subtidal species rarely experience hypoxia and are not as hypoxia tolerant. These interspecific differences in hypoxia tolerance is reflected in modifications to various steps in the oxygen transport cascade, whereby hypoxia tolerant sculpins show higher gill surface area, better hemoglobin O 2 binding affinity, and an overall lower oxygen consumption rate. In the present study, we focus on the mitochondria and the terminal protein of the oxygen transport cascade, cytochrome c oxidase (COX), to determine if oxygen use by the mitochondria differs among sculpin species that vary in hypoxia tolerance. Hypoxia tolerant species showed higher COX oxygen binding affinity (measured as a lower apparent K m for O 2 ) in both brain and liver, and a higher overall COX capacity. In order to provide a mechanistic hypothesis to explain the putatively adaptive changes in COX K m for O 2 , we performed in silico protein analyses of the deduced amino acid sequence of the mitochondrial‐encoded COX3 subunit, which is postulated as the entry point for O2 and protons into the COX protein. Our analysis suggests that variation in two amino acid residues (positions 55 and 224) on COX3 may affect cardiolipin binding and O2 movement, thus contributing to the variation in COX K m for O 2 . As such, we provide evidence for adaptive variation in COX function across sculpins that vary in hypoxia tolerance. Support or Funding Information This work was funded by an NSERC Discovery Grant to Jeffrey Richards.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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".