Metagenomic Analysis of Isotopically Enriched DNA
Bibliographic record
Abstract
This detailed protocol describes an approach for combining DNA stable-isotope probing-based enrichment, multiple displacement amplification (MDA), and metagenomics. Together, these three methodologies enable selective access to the genomes of uncultivated organisms that actively grow using isotopically labelled carbon and nitrogen sources. Incubations with stable-isotope-labelled substrates enrich isotopically labelled DNA from functionally relevant micro-organisms; this serves as a filter to reduce the complexity of the metagenome. The MDA step generates sufficient DNA from labelled nucleic acid for metagenomic library construction. Subsequently, genome fragments can be subjected to a variety of screens for phylogenetic or functional genes relevant to active community members. The MDA-generated DNA can also serve as template for direct high-throughput sequencing to aid reconstruction of metabolic pathways of those active organisms. Recent proof-of-concept studies have demonstrated that this novel combination of molecular methods can offer substantial enhancements to gene detection frequencies and may have great future potential for the discovery of novel genes, enzymes, and metabolic pathways.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".