Localization of Soluble <i>β</i>-Carbonic Anhydrase in the Marine Diatom <i>Phaeodactylum tricornutum</i>. Sorting to the Chloroplast and Cluster Formation on the Girdle Lamellae
Bibliographic record
Abstract
A beta-carbonic anhydrase (CA) in the marine diatom Phaeodactylum tricornutum (PtCA1) is encoded by the nuclear genome. This enzyme was previously found to be important for the operation of photosynthesis with a high affinity for dissolved inorganic carbon. A cDNA sequence that encodes PtCA1 (ptca1) was shown to possess a presequence of 138 bp (pre138), which encodes an N-terminal sequence of 46 amino acids (Pre46AA) that does not exist in the mature PtCA1. In this study, pre138 was ligated with the enhanced green fluorescent protein (GFP) gene (egfp), and introduced into P. tricornutum by microprojectile bombardment. Subsequently, the expressed Pre46AA-GFP fusion was shown to be localized in the chloroplast stroma, whereas the expressed GFP without Pre46AA was localized in the cytoplasm. Insertion of the DNA sequence, encoding a mature region of ptca1 (mptca1) between pre138 and egfp, resulted in the formation of particles with concentrated GFP fluorescence in the stroma of P. tricornutum. These particles, 0.3 to 3.0 mum in size, were shown to be distinct from the mitochondria and localized on the surface of the putative girdle lamella. The attachment of the initial one-half of the pre138 to the mptca1-egfp fusion caused the expressed GFP fusion to accumulate in areas surrounding the chloroplast, presumably due to the presence of the endoplasmic reticulum signal encoded by the initial half-sequence and to the absence of the chloroplast transit sequence. These results indicate that PtCA1 is targeted to the stroma by the bipartite sequences of Pre46AA and that the observed GFP particles are formed specifically in the stroma due to the function of the mptca1.
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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".