Constitutively Up-regulated Carbon Metabolism is an Adaptation to Low Temperature in the Antarctic Psychrophile Chlamydomonas sp. UWO241
Bibliographic record
Abstract
The Antarctic alga Chlamydomonas sp. UWO241 is an obligate psychrophile that thrives in the cold but is unable to survive at moderate, seemingly innocuous temperatures. We dissect the responses of UWO241 to temperature stress using global metabolomic approaches. UWO241 exhibits slow growth at 4°C, a temperature closest to its natural habitat, and faster growth at higher temperatures of 10-15°C. We demonstrate that the slower growth-rate characteristic of UWO241 at 4⁰C is not necessarily a hallmark of stress. UWO241 constitutively accumulates high levels of protective metabolites including soluble sugars, polyamines and antioxidants at a range of steady-state temperatures. In contrast, the mesophile Chlamydomonas reinhardtii accumulates these metabolites only during cold stress. Despite low growth rates, 4°C-grown UWO241 cultures had a higher capacity to respond to heat stress (24°C) and accumulated increased amounts of antioxidants, lipids and soluble sugars, when compared to cultures grown at 10-15°C. We conclude that the slower growth rate and the unique psychrophilic physiological characteristic of UWO241 grown at 4⁰C result in a permanently re-routed steady-state metabolism, which contributes to its increased resistance to heat stress. Our work adds to the growing body of research on temperature stress in psychrophiles, many of which are threatened by climate change.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".