<i>S</i> -adenosylhomocysteine treatment of adult female fibroblasts alters X-chromosome inactivation and improves <i>in vitro</i> embryo development after somatic cell nuclear transfer
Bibliographic record
Abstract
The poor outcome of somatic cell nuclear transfer (SCNT) is thought to be a consequence of incomplete reprogramming of the donor cell. The objective of this study was to investigate the effects of treatment with S-adenosylhomocysteine (SAH) a DNA demethylation agent, on DNA methylation levels and X-chromosome inactivation status of bovine female fibroblast donor cells and the subsequent impact on developmental potential after SCNT. Compared with non-treated controls, the cells treated with SAH revealed (i) significantly (P<0.05) reduced global DNA methylation, (ii) significantly (approximately 1.5-fold) increased telomerase activity, (iii) diminished distribution signals of methylated histones H3-3mK9 and H3-3mK27 on the presumptive inactive X-chromosome (Xi), (iv) alteration in the replication pattern of the Xi, and (v) elevation of transcript levels for X-chromosome linked genes, ANT3, MECP2, XIAP, XIST, and HPRT. SCNT embryos produced with SAH-treated donor cells compared with those derived from untreated donor cells revealed (i) similar cleavage frequencies, (ii) significant elevation in the frequencies of development of cleaved embryos to hatched blastocyst stage, and (iii) 1.5-fold increase in telomerase activity. We concluded that SAH induces global DNA demethylation that partially reactivates the Xi, and that a hypomethylated genome may facilitate the nuclear reprogramming process.
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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 | 0.000 | 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) | 0.001 | 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".