Signalling via type IA and type IB bone morphogenetic protein receptors (BMPR) regulates intramembranous bone formation, chondrogenesis and feather formation in the chicken embryo.
Bibliographic record
Abstract
Bone morphogenetic proteins (BMPs) signal via complexes of type I and type II receptors. In this study, we mapped the expression of type IA, type IB and type II receptors during craniofacial chondrogenesis and then perturbed receptor function in vivo with retroviruses expressing dominant-negative or constitutively active type I receptors. BmprIB was the only receptor expressed within all cartilages. BmprIA was initially expressed in cartilage condensations, but later decreased within cartilage elements. BmprII was expressed at low levels in the nasal septum and prenasal cartilage and at higher levels in other craniofacial cartilages. The maxillary prominence, which gives rise to several intramembranous bones, expressed both type I receptors. Misexpression of dnBMPRIB decreased the size of cartilages and bones on the treated side. In contrast, dnBMPRIA had no effect on the skeletal phenotype. The phenotypes of caBMPRIA and caBMPRIB were similar; both led to overgrowth of cartilage elements, thinner bones with fewer trabeculae and inhibition of feather development. Infection with constitutively active viruses resulted in ectopic expression of Msx1, Msx2 and Fgfr2 throughout the maxillary mesenchyme. These data suggest that the pattern of trabeculation in membranous bones derived from the maxillary prominence was related to the change in expression pattern and that Msx and Fgfr2 genes were downstream of both type I BMP receptors. We conclude that the requirement for the type IB is greater than for the type IA receptor but, when active, both receptors play similar roles in regulating bone, cartilage and feather formation in the skull.
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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".