Genomic characterisation of the ichthyotoxic prymnesiophyte<i>Chrysochromulina polylepis,</i>and the expression of polyketide synthase genes in synchronized cultures
Bibliographic record
Abstract
The widely distributed prymnesiophyte species Chrysochromulina polylepis is prominent and well known for occasional formation of ichthyotoxic blooms. The chemical structure of the C. polylepis toxin(s) has not yet been elucidated, but the associated haemolytic activity, potent membrane disruption interactions and toxicity to finfish and protists have led to the suggestion that they may be similar to the prymnesins of Prymnesium parvum. Such polyether toxins are presumably formed partially or completely via polyketide biosynthetic pathways. In this genetic study of C. polylepis, we generated and analysed a genomic DNA and a normalized cDNA library. We estimated a genome size of approximately 230 mbp based upon analysis of >1000 genomic library clones. Of the cDNA library, 3839 clones were partially sequenced and annotated, representing approximately 2900 unique contigs. We detected several genes putatively related to toxin synthesis. Thirteen putative polyketide synthase (PKS)-related gene sequences were identified and phylogenetic analysis identified two of these as containing ketoacyl domains of the modular type I PKS. Semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) was used to follow the expression of PKS genes over the light/dark cycle of synchronized C. polylepis cultures. This is the first study showing the expression of PKS genes in marine microalgae, in this case in the toxigenic C. polylepis.
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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".