Patterning and cell differentiation in<i>Hydra</i>: novel genes and the limits to conservation
Bibliographic record
Abstract
In the last few years more than 100 genes have been identified from Hydra, and well over 80 have been characterized. Since most genes are homologs of genes found in bilaterians, the genetic mechanisms for axial patterning and cell differentiation are evolutionarily conserved. This constitutes something of a paradox. If key developmental-control genes are the same in Hydra and all other organisms, how does one account for the marked differences in development and morphology of the different animal groups? How are taxon-specific features encoded? To examine whether in Hydra, in addition to conserved mechanisms, there are genetic features that control uniquely taxon-specific (Hydra/Hydrozoa/Cnidaria) aspects, we used an experimental strategy that does not require sequence data from related taxa. By means of this unbiased ("knowledge-independent") approach we have identified genes from Hydra encoding signal molecules and effector genes with no sequence similarity to genes in other organisms. When tested functionally, the novel genes were found to be essential for axial patterning and differentiation of Hydra-specific characteristics. Experimental analysis of the cis-regulatory apparatus of these novel genes reveals target sites for novel trans-acting factors. The use of unbiased screening approaches for several other organisms also reveals a large number of novel and taxon-specific genes of as yet unknown function. Thus, comparative data alone may not be sufficient for gaining a full understanding of the development of taxon-specific characteristics.
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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 | 0.000 |
| 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 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".