Comparison of Lichen-Forming Cyanobacterial and Green Algal Photobionts with Free-Living Algae
Bibliographic record
Abstract
Cyanobacteria of the genus Nostoc and green algae in the Chlorophyceae are widespread in nature and may occur in symbiotic associations with lichen-forming ascomycetes or as free-living cyanobacteria. Recent findings for some groups of lichens suggest that special lichen-forming photobiont lineages may exist independent of the free-living lineages, but few comparisons on photobiont growth, pigment, and polysaccharide production have been made. The goal of this study was to isolate photobionts, confirm their identity, and characterize their growth, pigment and polysaccharide production relative to free-living lineages. Algal growth, pigment contents, and polysaccharide concentration was measured using standard methods. The identification of Nostoc species was determined using transfer RNA for Leucine (trnL) nucleotide sequences and green algae using the internal transcribed spacer 1 of ribosomal DNA (ITS rDNA) sequences. An additional heptanucleotide repeat was present in the trnL gene of the Nostoc strain that associates with Leptogium rivulare. The biomass of pigment and polysaccharide production was highest in the lichenized Diplosphaera chodatii but the specific growth rate was highest in the free-living green alga, Chlorella vulgaris. The specific growth of the free-living Nostoc was higher than the lichenized Nostoc but pigment production was similar and polysaccharide production was lower than some of the lichenized Nostoc isolates. It was further hypothesized that the rates of growth, polysaccharide and pigment production may be key factors in compatibility of lichen algae with the fungus.
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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) | 0.001 | 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".