Distribution of the DNA transposon family, Pokey in the Daphnia pulex species complex
Why this work is in the frame
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Bibliographic record
Abstract
BACKGROUND: The Pokey family of DNA transposons consists of two putatively autonomous groups, PokeyA and PokeyB, and two groups of Miniature Inverted-repeat Transposable Elements (MITEs), mPok1 and mPok2. This TE family is unusual as it inserts into a specific site in ribosomal (r)DNA, as well as other locations in Daphnia genomes. The goals of this study were to determine the distribution of the Pokey family in lineages of the Daphnia pulex species complex, and to test the hypothesis that unusally high PokeyA number in some isolates of Daphnia pulicaria is the result of recent transposition. To do this, we estimated the haploid number of Pokey, mPok, and rRNA genes in 45 isolates from five Daphnia lineages using quantitative PCR. We also cloned and sequenced partial copies of PokeyA from four isolates of D. pulicaria. RESULTS: Haploid PokeyA and PokeyB number is generally less than 20 and tends to be higher outside rDNA in four lineages. Conversely, the number of both groups is much higher outside rDNA (~120) in D. arenata, and PokeyB is also somewhat higher inside rDNA. mPok1 was only detected in D. arenata. mPok2 occurs both outside (~30) and inside rDNA (~6) in D. arenata, but was rare (≤2) outside rDNA in the other four lineages. There is no correlation between Pokey and rRNA gene number (mean = 240 across lineages) in any lineage. Variation among cloned partial PokeyA sequences is significantly higher in isolates with high number compared to isolates with an average number. CONCLUSIONS: The high Pokey number outside rDNA in D. arenata and inside rDNA in some D. pulicaria isolates is consistent with a recent increase in transposition rate. The D. pulicaria increase may have been triggered by insertion of PokeyA into a region of transcriptionally active rDNA. The expansion in D. arenata (thought to be of hybrid origin) may be a consequence of release from epigenetic repression following hybridization. Previous work found D. obtusa to be very different from the D. pulex complex; mean PokeyA is higher in rDNA (~75), rDNA array size is nearly twice as large (415), and the two are positively correlated. The predominance of Pokey in only one location could be explained by purifying selection against ectopic recombination between elements inside and outside rDNA.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.000 | 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 it