A stem-deuterostome origin of the vertebrate pharyngeal transcriptional network
Bibliographic record
Abstract
Hemichordate worms possess ciliated gills on their trunk, and the homology of these structures with the pharyngeal gill slits of chordates has long been a topic of debate in the fields of evolutionary biology and comparative anatomy. Here, we show conservation of transcription factor expression between the developing pharyngeal gill pores of the hemichordate Saccoglossus kowalevskii and the pharyngeal gill slit precursors (i.e. pharyngeal endodermal outpockets) of vertebrates. Transcription factors that are expressed in the pharyngeal endoderm, ectoderm and mesenchyme of vertebrates are expressed exclusively in the pharyngeal endoderm of S. kowalevskii. The pharyngeal arches and tongue bars of S. kowalevskii lack Tbx1-expressing mesoderm, and are supported solely by an acellular collagenous endoskeleton and by compartments of the trunk coelom. Our findings suggest that hemichordate and vertebrate gills are homologous as simple endodermal outpockets from the foregut, and that much vertebrate pharyngeal complexity arose coincident with the incorporation of cranial paraxial mesoderm and neural crest-derived mesenchyme within pharyngeal arches along the chordate and vertebrate stems, respectively.
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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 | 0.001 | 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".