Phylogenetic analysis of intracellular bacteria of a harmful marine microalga, Heterocapsa circularisquama (Dinophyceae)
Bibliographic record
Abstract
Heterocapsa circularisquama, a noxious marine dinoflagellate, has frequently caused red tides and killed cultured bivalves in western Japanese embayments. Observations by electron and epifluorescence microscopy revealed that many bacterial particles were detected inside the H. circularisquama cells. To elucidate the identity and origin of the intracellular bacteria associated with H. circularisquama, bacterial 16S ribosomal RNA genes (16S rDNA) were directly amplified by polymerase chain reaction from 5 clonal cultures of the algal strains that had been isolated from different localities. After cloning, randomly selected clones including the bacterial 16S rDNA fragments were sequenced. The results showed that intracellular bacterial populations consisted of only 2 ribotypes of bacteria, even though the algal strains were established from different localities. One ribotype (bac-G), which was dominant in the intracellular bacterial population, belonged to the gamma-proteobacteria group, and the other (bac-F) clustered with the Flexibacter-Cytophaga-Bacteroides group. Both of these are novel species of endosymbiotic bacteria because of their unique 16S rDNA sequences. Furthermore, the populations of extracellularly associated bacteria were also composed of bac-G and bac-F, indicating that they originated from the intracellular bacteria. Fluorescence in situ hybridization targeting 16S rRNA indicated that bac-G appeared to localize on the algal nuclear surface, while bac-F was distributed in the cytoplasmic space of algal cells. These results strongly suggest that only a few species of specific bacteria reside and share their habitat in the H. circularisquama cells as endosymbionts.
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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 | 0.001 | 0.001 |
| 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 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".