Neurogenesis in sea urchin embryos and the diversity of deuterostome neurogenic mechanisms
Why this work is in the frame
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Bibliographic record
Abstract
A single origin to the diverse mechanisms of metazoan neurogenesis is suggested by the involvement of common signaling components and similar classes of transcription factors. However, in many forms we lack details of where neurons arise, patterns of cell division, and specific differentiation pathway components. The sea urchin larval nervous system is composed of an apical organ, which develops from neuroepithelium and functions as a central nervous system, and peripheral neurons, which differentiate in the ciliary band and project axons to the apical organ. To reveal developmental mechanisms of neurogenesis in this basal deuterostome, we developed antibodies to SoxC, SoxB2, ELAV and Brn1/2/4 and used neurons that develop at specific locations to establish a timeline for neurogenesis. Neural progenitors express, in turn, SoxB2, SoxC, and Brn1/2/4, before projecting neurites and expressing ELAV and SynB. Using pulse-chase labeling of cells with a thymidine analog to identify cells in S-phase, we establish that neurons identified by location are in their last mitotic cycle at the time of hatching, and S-phase is coincident with expression of SoxC. The number of cells expressing SoxC and differentiating as neurons is reduced in embryos injected with antisense morpholino oligonucleotides to SoxC, SoxB2 or Six3. Injection of RNA encoding SoxC into eggs does not enhance neurogenesis. In addition, inhibition of FGF receptors (SU5402) or a morpholino to FGFR1 reduces expression of SoxC. These data indicate that there are common features of neurogenesis in deuterostomes, and that sea urchins employ developmental mechanisms that are distinct from other ambulacraria.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it