The Corpuscles of Stannius, Calcium-Sensing Receptor, and Stanniocalcin: Responses to Calcimimetics and Physiological Challenges
Bibliographic record
Abstract
This study has examined whether the calcium-sensing receptor (CaSR) plays a role in control of stanniocalcin-1 (STC-1), the dominant calcium regulatory hormone of fish, comparable with that demonstrated for CaSR in the mediation of ionized calcium regulation of PTH secretion in mammals. In a previous study, we have cloned flounder STC-1 from the corpuscles of Stannius (CS). Here, we report the cloning and characterization of the CS CaSR, and the in vivo responses of this system to altered salinity, EGTA induced hypocalcemia, and calcimimetic administration. Quantitative PCR analysis demonstrated, for the first time, that the CS are major sites of CaSR expression in flounder. Immunoblot analysis of CS proteins with CaSR-specific antibodies revealed a broad band of approximately 215-300 kDa under nonreducing conditions, and bands of approximately 215-300 kDa and approximately 120-150 kDa under reducing conditions. There were no differences in CS CaSR mRNA expression or plasma STC-1 levels between seawater and freshwater (FW)-adapted fish, although CS STC-1 mRNA expression was lower in FW animals. Immunoblots showed that glycosylated monomeric forms of the CaSR migrated at a lower molecular mass in CS samples from FW animals. The ip administration of EGTA rapidly induced hypocalcemia, and a concomitant lowering of plasma STC-1. Calcimimetic administration (1 mg/kg R-568) rapidly increased plasma STC-1 levels, and reduced plasma concentrations of calcium, phosphate, and magnesium when compared with S-568-treated controls. Together, these findings support an evolutionary conserved role for the CaSR in the endocrine regulation of calcium before the appearance of parathyroid glands in tetrapods.
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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 | 0.001 |
| 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".