Sodium-hydrogen exchangers in C. elegans and their potential role in hypodermal H+ excretion, Na+ uptake, ammonia excretion and acid-base balance
Bibliographic record
Abstract
Cation/proton exchangers of the Cation proton antiporter 1 (CPA1) subfamily (NHEs, SLC 9) play an important role in many physiological processes, including cell volume regulation, acid-base homeostasis and ammonia excretion. The soil nematode Caenorhabditis elegans expresses nine paralogues (NHX-1 to -9) of these transporters, which all contain the highly conserved amiloride binding motif. The current study was undertaken to investigate the role of the cation/proton exchanger in hypodermal Na+ and H+ fluxes as well in ammonia excretion processes. Measurements using the scanning ion-selective electrode technique (SIET) showed that the hypodermis promotes H+ secretion as well as a Na+ uptake, indicating the participation of a cation/proton exchanger. Interestingly, while both fluxes, as well as whole body ammonia excretion rates were partially inhibited by amiloride (100 µmol l-1), no effect was observed on the H+ efflux and ammonia excretion rates when animals were exposed to 100 µmol l-1 EIPA, suggesting participation of apical Na+ channels in Na+ uptake, but probably not NHX transporters. In response to stress induced by starvation or exposure to 1 mmol l-1 NH4Cl (HEA), pH = 5.5, pH = 8.0), body pH stayed fairly constant, with changes of mRNA expression levels detected in intestinal NHX-2 and hypodermal NHX-3. Excretory cell NHX-9 was altered by exposure to pH 5.5 or 8.0 but not by HEA. In conclusion, the study suggest that apical localized EIPA-sensitive sodium/hydrogen exchangers do play a role in ammonia excretion and Na+ uptake in the hypodermis of C. elegans.
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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".