Variation in Its C-Terminal Amino Acids Determines Whether Endo-β-Mannanase Is Active or Inactive in Ripening Tomato Fruits of Different Cultivars
Bibliographic record
Abstract
Endo-beta-mannanase cDNAs were cloned and characterized from ripening tomato (Lycopersicon esculentum Mill. cv Trust) fruit, which produces an active enzyme, and from the tomato cv Walter, which produces an inactive enzyme. There is a two-nucleotide deletion in the gene from tomato cv Walter, which results in a frame shift and the deletion of four amino acids at the C terminus of the full-length protein. Other cultivars that produce either active or inactive enzyme show the same absence or presence of the two-nucleotide deletion. The endo-beta-mannanase enzyme protein was purified and characterized from ripe fruit to ensure that cDNA codes for the enzyme from fruit. Immunoblot analysis demonstrated that non-ripening mutants, which also fail to exhibit endo-beta-mannanase activity, do so because they fail to express the protein. In a two-way genetic cross between tomato cvs Walter and Trust, all F(1) progeny from both crosses produced fruit with active enzyme, suggesting that this form is dominant and homozygous in tomato cv Trust. Self-pollination of a plant from the heterozygous F(1) generation yielded F(2) plants that bear fruit with and without active enzyme at a ratio appropriate to Mendelian genetic segregation of alleles. Heterologous expression of the two endo-beta-mannanase genes in Escherichia coli resulted in active enzyme being produced from cultures containing the tomato cv Trust gene and inactive enzyme being produced from those containing the tomato cv Walter gene. Site-directed mutagenesis was used to establish key elements in the C terminus of the endo-beta-mannanase protein that are essential for full enzyme activity.
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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 | 0.000 | 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 | 0.000 |
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".