54 ESTABLISHMENT OF PREGNANCY BY OVINE NUCLEAR TRANSFER EMBRYOS RECONSTRUCTED USING CAFFEINE-TREATED <i>IN VITRO</i> -MATURED OOCYTES AS CYTOPLAST RECIPIENTS
Bibliographic record
Abstract
In embryos reconstructed by somatic cell nuclear transfer (SCNT), components of the oocyte cytoplasm are capable of reprogramming the somatic genome to control subsequent development. Although the mechanisms that control nuclear reprogramming are unknown, we have previously hypothesized that the occurrence of nuclear envelope breakdown (NEBD) and premature chromosome condensation (PCC) in the donor nucleus are beneficial. In previous studies we have demonstrated that treatment of ovine oocytes with caffeine (10 mM), a protein phosphatase inhibitor, increased the activities of both MPF and MAPK in enucleated oocytes (Lee and Campbell 2004 Reprod. Fertil. Dev. 16, 125) and additionally resulted in a significant increase in the occurrence of NEBD and PCC in donor nuclei. Furthermore, SCNT embryos reconstructed following caffeine treatment had significantly increased cell numbers at the blastocyst stage. More recently we have demonstrated that the use of caffeine treated ovine oocytes as cytoplast recipients can regulate the expression of several developmentally important genes in SCNT embryos, including Oct-4 and interferon-tau (Choi et al . 2006 Reprod. Fertil. Dev. 18, in press). This study was designed to establish the developmental potential of NT embryos reconstructed using caffeine treated oocytes as cytoplast recipients. Ear skin fibroblast cells established from a Merino ram were quiesced in DMEM containing 0.1% fetal bovine serum (FBS) for 3 days. Oocyte maturation and embryo reconstruction and culture were performed as previously described (Lee and Campbell 2004 Reprod. Fertil. Dev. 16, 125) with the exception that ovaries from Merino × Romney Marsh cross ewes were stimulated with FSH sponge (Folltropin®-V; Bioniche Animal Health, Beltsville, Ontario, Canada) and were collected at slaughter on Day 13 following sponging. Blastocyst stage embryos were surgically transferred to the uterine horn of synchronized Merino × Romney Marsh cross recipients (three blastocysts per recipient). Recipient ewes were scanned by ultrasonography at Days 30, 60, and 90 following embryo transfer. All data were analyzed by chi-square test. There were no differences in fusion (145/167; 86.8% vs. 174/205; 84.9%), cleavage (123/145; 84.8% vs. 135/174; 77.6%), or the development to blastocyst (33/145; 22.8% vs. 34/174; 19.5%) between control SCNT embryos and caffeine treated SCNT embryos. However, although the frequency of pregnancy between control and caffeine-treated NT groups (5/15; 33.3% vs. 7/14; 50.0%) at 30 days was not significantly different, control SCNT embryos showed significantly lower pregnancies (1/15; 6.7%) than caffeine treated SCNT embryos (4/14; 28.6%) at both 60 and 90 days. In conclusion, embryos reconstructed using caffeine-treated cytoplasts can induce pregnancy at the same frequency as untreated controls; furthermore, the results suggest that SCNT embryos produced in this way are more able to maintain pregnancy.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".