Cryospectroscopy Studies of Intact Light-Harvesting Antennas Reveal Empirical Electronic Energy Transitions in Two Cyanobacteria Species
Bibliographic record
Abstract
Understanding of electronic energy transition (EET) mechanisms from the light-harvesting unit to the reaction center in a natural system has been limited by (a) the use of conventional transient time-resolved spectroscopy at room temperature, which result in high signal-to-noise ratio and (b) examining extracts instead of intact light-harvesting units. Here, we report previously unknown differences and new insight in EET of two cyanobacteria species, Acaryochloris marina and Thermosynechoccocus vulcanus, which have been found only after using UV–vis, hole-burning, and fluorescence spectroscopy at ultralow temperature and examining their intact light-harvesting unit, phycobilisomes (PBS). Although the exciton formation is similarly induced by photoexcitation of chromophore assemblies in phycocyanin (PC) and allophycocyanin (APC) in PBSs of both species, the EET mechanisms are totally different, being adiabatic in A. marina and nonadiabatic in T. vulcanus . The PBS of A. marina has only one APC trimer and energy transfer is through coupling of α 84 in APC with β 84 in adjacent PC. In T. vulcanus, the PBS has three components: coupling between APC core and the entire PC rod and couplings of β–β 18 and of L CM to β in the adjacent APC-like trimer. A total of 80% of the excitation energy is trapped in the coupling β–β 18 and regulates the flow of energy from the high- to low-level terminal electronic transition emitter β-L CM . All these details cannot be observed at room temperature and in extracted units.
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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 | 0.000 |
| 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".