Polyketide synthases in St. John's wort (Hypericum perforatum L.) leaves: immunochemical studies and immunofluorescence localization
Bibliographic record
Abstract
Hypericum perforatum (St. John's wort; Clusiaceae) is an important medicinal plant, which is widely used as an antidepressant. The plant is characterized by the presence of different types of secretory tissue including translucent glands, black nodules and secretory canals. Hypericum species are ideal experimental systems for studying the biosynthesis of a diversity of aromatic polyketides. Two type III polyketide synthases (PKSs) involved are benzophenone synthase (BPS) and chalcone synthase (CHS), for which cDNAs were cloned and characterized. The present work describes immunochemical studies and immunofluorescence localization of these PKSs in H. perforatum leaves. Both enzymes were heterologously expressed in E. coli as 6xHis-tagged proteins and GST-fusion proteins. Polyclonal antibodies were raised against the 6xHis-tagged PKSs in rabbits and the IgG fractions were isolated. The specificity of the antibodies was examined using immunoblotting and immunotitration techniques. Protein extracts from different stages of H. perforatum leaves were subjected to SDS-PAGE and immunoblotting. While BPS expression was low, a high CHS level was found in young leaves. The tissue-specific localization of BPS and CHS was studied in different developmental stages of H. perforatum leaves using the immunofluorescence technique and confocal laser scanning microscopy. BPS was observed to a low extent in mesophyll cells of young leaves and strongly expressed in the glandular cells of large translucent glands present inside the leaves. CHS was strongly expressed in the mesophyll cells of young leaves and was absent from glands.
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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".