37 DEVELOPMENTAL POTENTIAL OF CLONE CELLS IN MURINE CLONE-FERTILIZED AGGREGATION CHIMERAS
Bibliographic record
Abstract
In both murine and porcine preimplantation stage clones, mosaicism in gene expression has been observed, indicating variation in transcription of some genes between cells of the individual clone (Boiani M et al., 2002 Genes Dev. 16, 1209–1219; Park KW et al., 2002 Biol. Reprod. 66, 1001–1005). This observation raises the question as to whether all blastomeres within one early-stage clone are equivalent, or whether there are differences in developmental potential. To address this, we aggregated preimplantation-stage clone embryos with fertilized embryos and assessed contribution of Oct4-GFP expressing cells of clone origin in blastocysts and in vitro outgrowths. In normal embryos, the Oct4-GFP transgene is expressed during preimplantation stages and reflects expression of Oct4 protein. Mouse cumulus cell clones were produced from cells transgenic for Oct4-GFP (Szabó PE et al., 2002 Mech. Dev. 115, 157–160) as described (Boiani M et al., 2002 Genes Dev. 16, 1209–1219). Four-cell-stage clones and synchronous fertilized non-transgenic embryos were aggregated in micro-wells after removal of the zona pellucida using acid Tyrode’s solution. Aggregates were cultured to the blastocyst stage in -MEM supplemented with bovine serum albumin (0.4% w/v). All control chimeras produced from four-cell-stage fertilized non-transgenic and Oct4-GFP transgenic embryos formed blastocysts, and 15 of 20 had GFP-expressing cells. The majority of clone-wild-type aggregates developed to the blastocyst stage (35/40); however, contribution of GFP-expressing cells was observed in fewer blastocysts compared to controls (12/35; P < 0.05). Contribution of GFP expressing clone cells to the ICM varied between 30% and 100% of cells as determined by subjective evaluation of GFP fluorescence overlaying bright-field images. During in vitro outgrowth formation of synchronous aggregation chimeras of clone and wild-type embryos, maintenance of clone contribution to the ICM mound was observed, but at a lower frequency (12% v. 34% at the blastocyst stage). The results suggest that aggregation with fertilized cells does not provide benefit to clone blastomeres during preimplantation stages. Possibly, clone blastomeres may not be competitive with wild-type blastomeres, or are developmentally asynchronous, which will be tested using asynchronous chimeras.
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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 | 0.000 | 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 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".