50 SPATIAL EXPRESSION OF OCT4 IS NORMALLY REGULATED IN PREIMPLANTATION STAGE BOVINE SOMATIC CELL CLONES
Bibliographic record
Abstract
Oct4 is a member of the POU family of transcription factors and is expressed in blastomeres, pluripotent embryonic cells and the germ cell lineage. In the mouse blastocyst, expression of Oct4 becomes restricted to the inner cell mass (ICM). In bovine, Oct4 has not been considered to be a marker for pluripotency because Oct4 protein is expressed in both the ICM and the trophectoderm (TE) of bovine blastocysts (van Eijk MJT et al., 1999 Biol. Reprod. 60, 1093–1103; Kirchhof N et al., 2000 Biol. Reprod. 63, 1698–1705). Oct4 has been used as a marker gene for nuclear reprogramming in cloned embryos. Aberrant spatial distribution and levels of Oct4 have been observed in the majority of mouse clone blastocysts and blastocyst outgrowths (Boiani M et al., 2002 Genes Dev. 16, 1209–1219), indicating reprogramming failure of mouse clones. Lack of or abnormal Oct4 protein expression was also observed in cloned monkey embryos (Mitalipov SM et al., 2003 Biol. Reprod. 68 (suppl 1), 159). The spatial distribution of Oct4 mRNA and protein in bovine clones has not been reported. Bovine oocytes were obtained from a commercial supplier (BOMED, Inc., Madison, WI, USA), and were matured in vitro. Enucleated oocytes were fused with fibroblasts from ear skin and then treated with 10 µg mL-1 cycloheximide and 1.25 µg mL-1 cytochalasin D for 6 h. Embryos were cultured in SOF supplemented with 1% fetal calf serum (FCS) at 39°C under 5% CO2, 5% O2 and 90% N2 for 2 days. At Day 2, embryos were transferred to SOF supplemented with 5% FCS and cultured under the same conditions until Day 7. Blastocysts were analyzed at Day 7. Oct4 mRNA expression was visualized by whole-mount in situ hybridization using a bovine Oct4-specific antisense riboprobe. Oct4 protein was detected by immunocytochemistry. Control embryos were produced by IVF and were cultured under the same conditions to the blastocyst stage (Day 7). We found that Oct4 mRNA signal was restricted to the ICM in bovine blastocysts. Bovine clones were not different from control embryos in that distribution of Oct4 mRNA signal was typically restricted to the ICM (14 of 16). In contrast to our previous report on mouse clones (Boiani M et al., 2002 Genes Dev. 16, 1209–1219), ectopic expression of Oct4 mRNA in the TE was rarely detected in bovine clones (2 of 16). Distribution of Oct4 protein was also similar between clones and controls with distribution in both the ICM and TE (clones: 9 of 9; controls: 9 of 9). It is unclear why defects in Oct4 distribution should differ between bovine and other species tested including monkey (Mitalipov SM et al., 2003 Biol. Reprod. 68 (suppl 1), 159–160); however, the higher rate of normal Oct4 distribution is consistent with the generally higher rates of postimplantation development of bovine clones (Shi W et al., 2003 Differentiation 71, 91–113).
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.004 |
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".