Phylogeny and Nucleomorph Karyotype Diversity of Chlorarachniophyte Algae
Bibliographic record
Abstract
Chlorarachniophytes are flagellated and/or reticulopod-forming marine algae with chlorophyll a- and b-containing plastids of secondary endosymbiotic origin. They are one of only two algal groups known to possess a "nucleomorph" (i.e. the remnant nucleus of the eukaryotic endosymbiont that donated the plastid). Apart from the recently sequenced nucleomorph genome of Bigelowiella natans, little is known about the size, structure, and composition of chlorarachniophyte nucleomorph genomes. Toward the goal of better understanding nucleomorph genome diversity, as well as establishing a phylogenetic framework with which to interpret variation in chlorarachniophyte morphology, ultrastructure, and life cycle, we are studying a wide range of chlorarachniophyte strains from public culture collections and natural habitats. We have obtained 22 new chlorarachniophyte nuclear and nucleomorph 18S rRNA gene (18S rDNA) sequences and nucleomorph genome size estimates for 14 different strains. Consistent with previous studies, all of the chlorarachniophytes examined appear to possess three nucleomorph chromosomes. However, our results suggest considerable variation in nucleomorph genome size and structure, with individual chromosome sizes ranging from approximately 90 to approximately 210 kbp, and total genome sizes between approximately 330 kbp in Lotharella amoebiformis and approximately 610 kbp in unidentified chlorarachniophyte strain CCMP622. The significance of these phylogenetic and nucleomorph karyotype data is discussed.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".