Genomic plasticity in prokaryotes: the case of the square haloarchaeon
Bibliographic record
Abstract
The variability in genome content among closely related strains of prokaryotes has been one of the most remarkable discoveries of genomics. One way to approach the description of this so-called pan-genome is to compare one reference strain genome with metagenomic sequences from the environment. We have applied this approach to one extreme aquatic habitat, saturated brines in a solar saltern. The genome of Haloquadratum walsbyi strain DSM 16790 was compared to an environmental metagenome obtained from the exact site of its isolation. This approach revealed that some regions of the strain genome were scarcely represented in the metagenome. Here we have analyzed these genomic islands (GI) in the genome of DSM 16790 and compared them with the complete sequence of some fosmids from the environmental library. Two of the islands, GI 2 and GI 4, overlapped with two large guanine and cytosine (GC)-rich regions that showed evidence of high variability through mobile elements. GI 3 seemed to be a phage or phage-remnant acquired by the reference genome, but not present in most environmental lineages. Most differential gene content was related to small molecule transport and detection, probably reflecting adaptation to different pools of organic nutrients. GI 1 did not possess traces of mobile elements and had normal GC content. This island contained the main cluster of cell envelope glycoproteins and the variability found was different from the other GIs. Rather than containing different genes it consisted of homologs with low similarity. This variation might reflect a phage evasion strategy.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 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".