BMP and WNT signaling are involved in tracheal cartilage development in chicken embryos
Bibliographic record
Abstract
The respiratory system consists of the tracheal tube which extends from the back of the mouth, down the neck and branches into the bronchial tubes of the lungs, which are the major sites of respiration. Cartilaginous rings are present along the length of the trachea and are essential for keeping the airways open. Understanding trachea and cartilage development is crucial to better understanding respiratory disorders and diseases. We analyzed cartilage development across different chicken embryonic stages using a combination of cellular and molecular biology tools. We found that chondrogenic condensations are barely visible histologically from HH35 (E8.5) while differentiated cartilage rings are distinct by HH36 (E10). In situ hybridisation data shows that Bmp2 is expressed in a ring-like pattern along the length of the tracheal tube from HH36. We further show that BMP2, but not BMP4, colocalises with COL2A1. qPCR data shows that genes such as COL2A1 , and WNT are substantially upregulated between HH34 to HH37, while other genes (e.g. SHH, TBX4/5 ) are downregulated. Within this three to four day period, we detected a reduction in SHH and WNT during cartilage condensation formation and an upregulation of COL2A1 and WNT during overt cartilage differentiation. We next used a known Bmp2 type 1 receptor inhibitor (DMH1) to attempt to disrupt tracheal cartilage development. Following inhibition, we observed a widening and lengthening of the tracheal cartilage rings with some narrowing of the spaces between the rings. Our gene expression analysis reveals significant increases in COL2A1, WNT, and BMP4 following BMP receptor blocking compared to sham controls and indicates that these genes are important for the molecular response that results in patterning the tracheal cartilage ring morphology. This study provides a framework to further understand development of these important airway cartilages in the avian model. • Tracheal cartilage condensations begin at around HH35 (E8.5-9) in chicken embryos, 1-1.5 days before distinct rings appear at HH36 (E10) • Strong and ubiquitous BMP2 expression is present at HH35 and is not restricted to chondrogenic condensations however it is expressed in the cartilage rings by HH36 • COL2A1 and WNT2 are significantly elevated between HH34 and HH37 in the trachea • COL2A1 co-localises with BMP2 but not with BMP4 in the tracheal cartilages • DMH1 inhibition of type 2 BMP receptors results in wider and longer cartilage rings, with significant increases in BMP4, Col2A1 and WNT2 expression.
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".