50 SPATIAL EXPRESSION OF OCT4 IS NORMALLY REGULATED IN PREIMPLANTATION STAGE BOVINE SOMATIC CELL CLONES
Notice bibliographique
Résumé
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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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».