Claudin-3 tight junction proteins in<i>Tetraodon nigroviridis</i>: cloning, tissue-specific expression, and a role in hydromineral balance
Bibliographic record
Abstract
Claudins are a large family of integral transmembrane tight junction (TJ) proteins involved in regulating the permeability of the paracellular pathway. In these studies, we clone and describe the tissue distribution of four claudin-3 genes (designated Tncldn3a, Tncldn3b, Tncldn3c, and Tncldn3d) from the euryhaline spotted green puffer fish Tetraodon nigroviridis and examine the response of Tetraodon and Tncldn3 mRNAs to salinity variation (freshwater, FW; seawater, SW; and hypersaline seawater, HSW). In Tetraodon, genes encoding for claudin-3 TJ proteins are widely expressed, suggesting that claudin-3 proteins participate in regulating paracellular permeability across various epithelia within fishes. Of particular note is the widespread distribution of Tncldn3 genes in tissues that regulate hydromineral balance (gills, skin, kidney, and intestine). Renal and intestinal tissues express all four Tncldn3 genes, while the gills and skin specifically express Tncldn3a and Tncldn3c. In response to salinity variation, Tetraodon exhibits characteristics typical of a euryhaline fish species: moderate changes in blood osmolality and muscle moisture content; alterations in gill, kidney, and intestinal Na(+)-K(+)-ATPase activity; and unaltered Na(+)-K(+)-ATPase activity in the integument. In conjunction with these changes, Tncldn3 mRNA expression exhibits marked and significant salinity-dependent alterations that are both tissue and gene specific. Overall, our data suggest that a decreased abundance of claudin-3 in Tetraodon occurs in "leakier" epithelia and that claudin-3 TJ proteins will likely play an important role in the maintenance of hydromineral balance across osmoregulatory epithelia of euryhaline fishes.
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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".