Characterization of Na+ uptake in the endangered desert pupfish, Cyprinodon macularius (Baird and Girard)
Bibliographic record
Abstract
This study provided an initial characterization of Na(+) uptake in saline freshwater by the endangered pupfish, Cyprinodon macularius. This species occurs only in several saline water systems in the southwestern USA and northern Mexico, where salinity is largely controlled by water-management practices. Consequently, understanding the osmoregulatory capacity of this species is important for their conservation. The lower acclimation limit of C. macularius in freshwater was found to be 2 mM Na(+). Fish acclimated to 2 or 7 mM Na(+) displayed similar Na(+) uptake kinetics, with K m values of 4321 and 3672 μM and V max values of 4771 and 3602 nmol g(-1) h(-1), respectively. A series of experiments using pharmacological inhibitors indicated that Na(+) uptake in C. macularius was not sensitive to bumetanide, metolazone, or phenamil. These results indicate the Na(+)-K(+)-2Cl(-) cotransporter, Na(+)-Cl(-) cotransporter, and the Na(+) channel-H(+)-ATPase system are likely not to be involved in Na(+) uptake at the apical membrane of fish gill ionocytes in fish acclimated to 2 or 7 mM Na(+). However, Na(+) uptake was sensitive to 1 × 10(-3) M amiloride (not 1 × 10(-4) or 1 × 10(-5) M), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), and ethoxzolamide. These data suggest that C. macularius relies on a low-affinity Na(+)-H(+) exchanger for apical Na(+) uptake and that H(+) ions generated via carbonic anhydrase-mediated CO2 hydration are important for the function of this protein.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".