Spatial Distribution of Histone Isoforms on the Bovine Active and Inactive X Chromosomes
Bibliographic record
Abstract
The inactive X chromosome (Xi) in female mammals serves as an important model for studying the role of histone isoforms in directing specific nuclear processes leading to inherited differences in transcription. In the present study, we investigated the distribution of some histone isoforms known to be involved in the process of human X inactivation on their bovine counterparts. To ascertain the identity of active and inactive X chromosome, their distribution was investigated on the X chromosomes in a cell line derived from a bovine female carrying an X;autosome translocation rcp(Xp+;23q-) which allowed the recognition of the maternal (translocated) and paternal (normal) X chromosome. The distribution patterns of histone H3 trimethylated at lysine 9 (H3K9me3) and trimethylated at lysine 27 (H3K27me3), and histone macroH2A1 and macroH2A2 (isoforms specific to heterochromatin) were determined by immunocytochemistry and compared to the temporal pattern of replication using BrdU pulse labeling prior to staining. Immunostaining revealed that H3K9me3, H3K27me3, and macroH2A1 are preferentially concentrated on the Xi, whereas the histone variant macroH2A2 is not a marker for this chromosome. H3K9me3, H3K27me3, and macroH2A1 were consistently located in bands along the Xi, while H3K9me3, macroH2A1 and macroH2A2 localized in the pericentromeric regions of the autosomes. H3K27me3 identified two intense bands on the Xi at Xp22 and Xq31, representing the early replication regions of the chromosome. H3K27me3 and macroH2A1 overlapped in the Xq31 region. It was concluded that different heterochromatin regions on the bovine inactive X chromosome can be identified by their histone isoform composition.
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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".