Quantification of the retrotransposon BARE-1 reveals the dynamic nature of the barley genome
Bibliographic record
Abstract
We used quantitative real-time PCR analysis to measure the copy number of the BARE-1 retrotransposon in 5 cultivars of barley (Hordeum vulgare), as well as in samples from its wild relative, Hordeum spontaneum. Two sets of PCR primers were used to amplify regions within the long terminal repeat (LTR) and the reverse transcriptase (RT) gene of BARE-1 (GenBank accession Z17327). The LTR primers detected an average of 2.148 x 105 +/- 0.012 x 105 copies per haploid genome among barley samples, whereas the RT primers detected an average of 1.588 x 104 +/- 0.085 x 104 copies. The average ratio of LTR:RT was estimated to be 13.5:1. This finding indicates that more than 7% of the barley genome is occupied by BARE-1 elements in the form of solo LTRs and another 2.6% of the genome is occupied by the full-length element. Taken together, BARE-1 sequences represent approximately 9.6% of the barley genome among the barley plants used in this study. For the above estimation, a genome size of 5.44 x 103 Mb for H. vulgare and 5.39 x 103 Mb for H. spontaneum were assumed. Our study on quantification results of the BARE-1 for a small group of barley cultivars showed that there are significant differences among cultivars in terms of BARE-1 copy number, providing further evidence that BARE-1 is active and has a major role in shaping the barley genome as a result of breeding and selection. Quantification results also showed that most of the elements (> 90%) are present as truncated copies (solo LTRs). These results show that there is a high level of recombination leading to the formation of truncated elements and a subsequent DNA loss from the genome. Taken together, our study provides a glimpse into a dynamic micro-evolutionary process that is the by-product of genome reshuffling and directional selection in barley breeding programs.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".