73 ABNORMAL REPROGRAMMING OF HISTONE ACETYLATION IN CLONED BOVINE EMBRYOS
Bibliographic record
Abstract
Histone acetylation plays an important role in the chromatin structure prior to zygotic gene expression during early embryonic development. Successful animal clones indicate that differentiated somatic nuclei must be reprogrammed to some extent during pre-implantation development. However, the molecular mechanisms regarding epigenetic reprogramming of somatic nuclei in the early-stage embryos are poorly understood. To test this, the patterns of hyperacetylated histone H4 lysine 5 (AcH4K5) in the nuclear-transferred (NT) embryos were monitored, comparing in vitro fertilized (IVF) embryos and Trichostatin A (TSA)-NT embryos with TSA-treated cells. The intensity signals of AcH4K5 were observed in early-stage embryos and somatic cells (bovine ear skin fibroblasts composed of about 80% at G0/G1 stage) by immunofluorescence analysis with anti-AcH4K5 using image the analyzer system, SigmaScan-pro V5.01 (SPSS, Inc., Chicago, IL, USA). Our data were analyzed by analysis of variance (ANOVA) using an SAS package (SAS Institute, Inc., Cary, NC, USA). Somatic cells were exposed to TSA (1 µM for 60 h), a specific inhibitor of histone deacetylase (HDAC), to induce hyperacetylation prior to somatic cell nuclear transfer. Signal intensity for AcH4K5 in TSA-treated cells (n = 80) was significantly increased (P < 0.05), which was approximately double compared to that of normal cells (n = 80). In normal cells, histone H4 acetylation was profoundly reduced from the pro-metaphase to the early telophase and then reappeared at the late telophase. Acetylation signals of TSA-treated cells gradually increased to the early anaphase, abruptly decreased at the late anaphase and the early telophase, and recovered during late telophase. During early embryonic development (1 cell to 8 cell stage), NT embryos (n = 8) were hypoacetylated at the metaphase, whereas IVF (n = 10) and TSA-NT embryos (n = 8) were hyperacetylated. Our findings demonstrate that aberrant epigenetic reprogramming of histone modification occurs as early as the pronuclear stage in cloned embryos.
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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".