Reactive oxygen species are required for spore-wall formation in <i>Physcomitrella patens</i>
Bibliographic record
Abstract
A robust spore wall was a key requirement for terrestrialization by early plants. Sporopollenin in spore and pollen grain walls is thought to be polymerized and cross-linked to other macromolecular components, partly through oxidative processes involving H 2 O 2 . Therefore, we investigated effects of scavengers of reactive oxygen species (ROS) on the formation of spore walls in the moss Physcomitrella patens (Hedw.) Bruch, Schimp & W. Gümbel. Exposure of sporophytes, containing spores in the process of forming walls, to ascorbate, dimethylthiourea, or 4-hydroxy-TEMPO prevented normal wall development in a dose, chemical, and stage-dependent manner. Mature spores, exposed while developing to a ROS scavenger, burst when mounted in water on a flat slide under a coverslip (a phenomenon we named “augmented osmolysis” because they did not burst in phosphate-buffered saline or in water on a depression slide). Additionally, the walls of exposed spores were more susceptible to alkaline hydrolysis than those of the control spores, and some were characterized by discontinuities in the exine, anomalies in perine spine structure, abnormal intine and aperture, and occasionally, wall shedding. Our data support the involvement of oxidative cross-linking in spore-wall development, including sporopollenin polymerization or deposition, as well as a role for ROS in intine/aperture development.
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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) | 0.000 | 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".