Bibliographic record
Abstract
Group II introns are widely believed to have been ancestors of spliceosomal introns, yet little is known about their own evolutionary history. In order to address the evolution of mobile group II introns, we have compiled 71 open reading frames (ORFs) related to group II intron reverse transcriptases and subjected their derived amino acid sequences to phylogenetic analysis. The phylogenetic tree was rooted with reverse transcriptases (RTs) of non-long terminal repeat retroelements, and the inferred phylogeny reveals two major clusters which we term the mitochondrial and chloroplast-like lineages. Bacterial ORFs are mainly positioned at the bases of the two lineages but with weak bootstrap support. The data give an overview of an apparently high degree of horizontal transfer of group II intron ORFs, mostly among related organisms but also between organelles and bacteria. The Zn domain (nuclease) and YADD motif (RT active site) were lost multiple times during evolution. Differences in domain structures suggest that the oldest ORFs were concise, while the ORF in the mitochondrial lineage subsequently expanded in three locations. The data are consistent with a bacterial origin for mobile group II introns.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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 source (direct Gemma or distilled Codex), 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".