The protochordate <i>Ciona intestinalis</i> as a model system for peripheral actions of GnRH
Bibliographic record
Abstract
In vertebrates, GnRH binds to its receptor and stimulates predominantly G(q/11)‐mediated signal transduction in gonadotropes. However, little is known about the GnRH receptor and its signaling pathway in the protochordate tunicates (sea squirts) a group that arose before the vertebrates and lacks both a pituitary gland and sex steroids. We have recently identified two genes in Ciona intestinalis that each code for three GnRH peptides. The structure of the six peptides is closely related to vertebrates GnRHs and each is bioactive in the C. intestinalis reproductive system. The genes for the ligands are expressed in the neural complex as well as peripheral tissues including the gonads and intestine. Furthermore, we identified in the genome and characterized four GnRH receptors that have a wide tissue distribution, including heart, neural complex, intestine, and gonads. The four GnRH receptors were all transcribed into messenger RNA, and three were biologically active in our COS‐7 cell assays; work on the fourth receptor is in progress. Three C. intestinalis receptors almost exclusively activated the cAMP pathway. In contrast, only GnRH receptor 1 activated inositol phosphate turnover in response to one of the native C. intestinalis GnRHs. In summary, our current understanding of GnRH function in C. intestinalis is a model of a decentralized GnRH regulatory axis in which the ligand and receptor structures have been generally conserved but may have shifted the dominant signaling pathways that are activated.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".