Reductive evolution of the DNA replication machinery in endosymbiotic fungi
Bibliographic record
Abstract
Abstract The molecular machinery for replicating and repairing DNA accurately is critically important for life and highly conserved across the Tree of Life. Here we show that two major lineages of fungi, Glomeromycotina and Microsporidia, lost DNA polymerase complexes involved in replication and translesion synthesis. Catalytic and non-catalytic subunits of DNA polymerases are co-eliminated, consistent with their physical and functional interactions described in other eukaryotes. We detect lineage-specific variation in genome-wide mutation rates, showing that DNA polymerase gene losses correlate with increased genetic variation. We find that the Glomeraceae family of arbuscular mycorrhizal (AM) fungi has lived for ∼360 My without a leading strand replisome, raising the question of how these fungi can replicate DNA. We provide evidence that the cell cycle of Rhizophagus irregularis is active when in symbiosis with a host, but not without. This indicates a higher level of integration between AM fungi and plants than previously appreciated, and suggests the existence of a regulatory or functional contribution provided by a host to the fungal cell cycle. We propose that alternative modes of DNA replication and cell cycle provide mutational opportunities for fungal adaptation, and play roles in the evolution of endosymbioses.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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".