Pharmacological inhibition of H3K27 trimethylation in bovine IVP embryos
Bibliographic record
Abstract
Genes associated to organogenesis, morphogenesis and embryonic development are temporarily suppressed in pluripotent cells of mammalian embryos by the trimethylation of lysine 27 of histone H3 (H3K27 me3). H3K27 methylation is catalyzed by enzymes of the Polycomb Repressive Complex 2 (PRC2); however, this process is not entirely known. The AdoHcy hydrolase inhibitor 3-Deazaneplanocin A (DZNep) can prevent the action of the PRC2 enzymes, therefore inhibiting H3K27 me3. Nevertheless, there are no reports of the action of DZNep in embryos. The aim of this study was to evaluate the blastocyst rate and the cell number of bovine embryos cultured with 5 µM DZNep from day 3 (D3) or day 5 (D5) of embryonic development. Oocytes from Nelore females obtained from slaughterhouse ovaries were subjected to in vitro maturation (IVM) for 24 h at 38.5 °C, with 5% CO2 in air and saturated humidity. In vitro fertilization (IVF) was performed with a previously tested frozen-thawed semen from a Nelore bull. Oocytes and spermatozoa remained in coculture for 22 h under the same conditions of IVM. At D3 (considering the day of IVF as D0), the cleaved embryos were randomly separated into 3 groups: exposed to 5 mM DZNep from D3 (DZNep D3; n = 80), exposed to 5 mM DZNep from D5 (DZNep D5; n = 81) or without the addition of DZNep (control group; n = 82). Four replicates were performed, and the blastocyst rates were assessed at D8. All fertilized structures (not only the blastocysts) were fixed in 4% paraformaldehyde and the cell nuclei were stained with DAPI to estimate the number of cells. Blastocyst rates were compared between the treatments using a logistic regression test and the average number of cells by analysis of variance followed by Tukey test, with 5% of significance level. The blastocyst rate obtained with the control group was 34.1%, higher than the ones obtained with groups DZNep D3 (11.2%) and DZNep D5 (7.4%), which did not differ. The average cell number of the control group was 38.7, higher than the average cell number of groups DZNep D3 (7.5) and DZNep D5 (6.4), which did not differ. Based on these results, it can be concluded that H3K27 me3 plays an important role in embryonic gene regulation because its inhibition results in decreased blastocyst rates and the produced embryos have fewer cells.
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How this classification was reachedexpand
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 | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".