Cytoplasmic carbonic anhydrase isozymes in rainbow trout<i>Oncorhynchus mykiss</i>: comparative physiology and molecular evolution
Bibliographic record
Abstract
It is well established that the gills of teleost fish contain substantial levels of cytoplasmic carbonic anhydrase (CA), but it is unclear which CA isozyme(s) might be responsible for this activity. The objective of the current study was to determine if branchial CA activity in rainbow trout was the result of a general cytoplasmic CA isozyme, with kinetic properties, tissue distribution and physiological functions distinct from those of the red blood cell (rbc)-specific CA isozyme. Isolation and sequencing of a second trout cytoplasmic CA yielded a 780 bp coding region that was 76% identical with the trout rbc CA (TCAb), although the active sites differed by only 1 amino acid. Interestingly, phylogenetic analyses did not group these two isozymes closely together, suggesting that more fish species may have multiple cytoplasmic CA isozymes. In contrast to TCAb, the second cytoplasmic CA isozyme had a wide tissue distribution with high expression in the gills and brain, and lower expression in many tissues, including the red blood cells. Thus, unlike TCAb, the second isozyme lacks tissue specificity and may be expressed in the cytoplasm of all cells. For this reason, it is referred to hereafter as TCAc (trout cytoplasmic CA). The inhibitor properties of both cytoplasmic isozymes were similar (Ki acetazolamide 1.21+/-0.18 nmol l(-1) and 1.34+/-0.10 nmol l(-1) for TCAc and TCAb, respectively). However, the turnover of TCAb was over three times greater than that of TCAc (30.3+/-5.83 vs 8.90+/-1.95 e4 s(-1), respectively), indicating that the rbc-specific CA isoform was significantly faster than the general cytoplasmic isoform. Induction of anaemia revealed differential expression of the two isozymes in the red blood cell; whereas TCAc mRNA expression was unaffected, TCAb mRNA expression was significantly increased by 30- to 60-fold in anaemic trout.
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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) | 0.000 | 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".