<i>N</i>-Ethyl-<i>N</i>-Nitrosourea (ENU) Mutagenesis Reveals an Intronic Residue Critical for<i>Caenorhabditis elegans</i>3′ Splice Site Function<i>in Vivo</i>
Bibliographic record
Abstract
Metazoan introns contain a polypyrimidine tract immediately upstream of the AG dinucleotide that defines the 3' splice site. In the nematode Caenorhabditis elegans, 3' splice sites are characterized by a highly conserved UUUUCAG/R octamer motif. While the conservation of pyrimidines in this motif is strongly suggestive of their importance in pre-mRNA splicing, in vivo evidence in support of this is lacking. In an N-ethyl-N-nitrosourea (ENU) mutagenesis screen in Caenorhabditis elegans, we have isolated a strain containing a point mutation in the octamer motif of a 3' splice site in the daf-12 gene. This mutation, a single base T-to-G transversion at the -5 position relative to the splice site, causes a strong daf-12 loss-of-function phenotype by abrogating splicing. The resulting transcript is predicted to encode a truncated DAF-12 protein generated by translation into the retained intron, which contains an in-frame stop codon. Other than the perfectly conserved AG dinucleotide at the site of splicing, G at the -5 position of the octamer motif is the most uncommon base in C. elegans 3' splice sites, occurring at closely paired sites where the better match to the splicing consensus is a few bases downstream. Our results highlight both the biological importance of the highly conserved -5 uridine residue in the C. elegans 3' splice site octamer motif as well as the utility of using ENU as a mutagen to study the function of polypyrimidine tracts and other AU- or AT-rich motifs in vivo.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.000 |
| 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".