Highlightable Ca<sup>2+</sup> Indicators for Live Cell Imaging
Bibliographic record
Abstract
Two of the most powerful implementations of fluorescent protein (FP) technology are "highlighters", which can be converted from nonfluorescent to fluorescent or from one color to another by illumination, and calcium ion (Ca(2+)) indicators. Combining the properties of both of these FP classes into a single construct would produce a highlightable Ca(2+) indicator that would enable researchers to mark a single cell spectrally in a transfected tissue and image its intracellular Ca(2+) dynamics. In an effort to create such a hybrid tool, we explored three different protein design strategies. The strategy that ultimately proved successful involved the creation of a circularly permuted version of a green-to-red photoconvertible FP and its introduction into a G-CaMP-type single-FP-based Ca(2+) indicator. Optimization by directed evolution led to the identification of two promising variants that exhibit excellent photoconversion properties and have an up to 4.6-fold increase in red fluorescence intensity upon binding of Ca(2+). We demonstrate the utility of these variants in HeLa cells and rat hippocampal neurons.
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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 | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".