Glucose-6-Phosphate Dehydrogenase Regulation in Anoxia Tolerance of the Freshwater Crayfish <i>Orconectes virilis</i>
Bibliographic record
Abstract
Glucose-6-phosphate dehydrogenase (G6PDH), the enzyme which catalyzes the rate determining step of the pentose phosphate pathway (PPP), controls the production of nucleotide precursor molecules (R5P) and powerful reducing molecules (NADPH) that support multiple biosynthetic functions, including antioxidant defense. G6PDH from hepatopancreas of the freshwater crayfish (Orconectes virilis) showed distinct kinetic changes in response to 20 h anoxic exposure. K(m) values for both substrates decreased significantly in anoxic crayfish; K(m) NADP(+) dropped from 0.015 ± 0.008 mM to 0.012 ± 0.008 mM, and K(m) G6P decreased from 0.13 ± 0.02 mM to 0.08 ± 0.007 mM. Two lines of evidence indicate that the mechanism involved is reversible phosphorylation. In vitro incubations that stimulated protein kinase or protein phosphatase action mimicked the effects on anoxia on K(m) values, whereas DEAE-Sephadex chromatography showed the presence of two enzyme forms (low- and high-phosphate) whose proportions changed during anoxia. Incubation studies implicated protein kinase A and G in mediating the anoxia-responsive changes in G6PDH kinetic properties. In addition, the amount of G6PDH protein (measured by immunoblotting) increased by ∼60% in anoxic hepatopancreas. Anoxia-induced phosphorylation of G6PDH could contribute to modifying carbon flow through the PPP under anoxic conditions, potentially maintaining NADPH supply for antioxidant defense during prolonged anoxia-induced hypometabolism.
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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".