<i>Empty pericarp7</i> encodes a mitochondrial E–subgroup pentatricopeptide repeat protein that is required for <i>ccm</i><scp><i>F</i><sub><i>N</i></sub></scp> editing, mitochondrial function and seed development in maize
Bibliographic record
Abstract
RNA editing, converting cytidines (C) to uridines (U) at specific sites in the transcripts of mitochondria and plastids, plays a critical role in organelle gene expression in land plants. Recently pentatricopeptide repeat (PPR) proteins were identified as site-specific recognition factors for RNA editing. In this study, we characterized an empty pericarp7 mutant (emp7) in Zea mays (maize), which confers an embryo-lethal phenotype. In emp7 mutants, mitochondrial functions are seriously perturbed, resulting in a strikingly reduced respiration rate. Emp7 encodes an E-subgroup PPR protein that is localized exclusively in the mitochondrion. Null mutation of Emp7 abolishes the C → U editing of ccmF(N) transcript solely at position 1553. CcmF(N) is coding for a subunit of heme lyase complex in the cytochrome c maturation pathway. The resulting Phe → Ser substitution in CcmF(N) leads to the loss of CcmF(N) protein and a strikingly reduced c-type cytochrome. Consequently, the mitochondrial cytochrome-linked respiratory chain is impaired as a result of the disassembly of complex III in the emp7 mutant. These results indicate that the PPR-E subgroup protein EMP7 is required for C → U editing of ccmF(N) -1553 at a position essential for cytochrome c maturation and mitochondrial oxidative phosphorylation, and hence is essential to embryo and endosperm development in maize.
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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) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".