Ciliary photoreceptors in sea urchin larvae indicate pan-deuterostome cell type conservation
Bibliographic record
Abstract
ABSTRACT One of the signatures of evolutionarily related cell types is the expression of similar combinations of transcription factors in distantly related animals. Here we present evidence that sea urchin larvae possess bilateral clusters of ciliary photoreceptors that are positioned in the oral/anterior apical neurogenic domain and associated with pigment cells. The expression of synaptotagmin indicates that the photoreceptors are neurons. Immunostaining shows that the sea urchin photoreceptors express an RGR/G O -opsin, opsin3.2, which co-localizes with tubulin on immotile cilia on the cell surface. Furthermore, orthologs of several transcription factors expressed in vertebrate photoreceptors are expressed in sea urchin ciliary photoreceptors, including Otx, Six3, Tbx2/3, and Rx, a transcription factor typically associated with ciliary photoreceptors. Analysis of gene expression during sea urchin development indicates that the photoreceptors derive from the anterior apical neurogenic domain. Thus, based on location, developmental origin, and transcription factor expression, sea urchin ciliary photoreceptors are likely homologous to vertebrate rods and cones. However, we found that genes typically involved in eye development in many animals, including pax6 , six1/2 , eya , and dac , are not expressed in sea urchin ciliary photoreceptors. Instead, all four genes are co-expressed in the hydropore canal, indicating that these genes operate as a module in an unrelated developmental context. Thus, based on current evidence, we conclude that at least within deuterostomes, ciliary photoreceptors share a common evolutionary origin and express a shared regulatory state that includes Rx, Otx, and Six3, but not transcription factors that are commonly associated with the retinal determination circuit.
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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) | 0.001 | 0.001 |
| 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 | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".