70 RECONSTRUCTED BOVINE BLASTOCYSTS COMPRISING NUCLEAR TRANSFER-DERIVED INNER CELL MASS AND TROPHECTODERM FROM IVF EMBRYOS DO NOT IMPROVE IN VIVO DEVELOPMENT OF CLONES
Notice bibliographique
Résumé
The cloning of cattle by somatic cell nuclear transfer (NT) is associated with a high incidence of abnormal placentation, excessive fluid accumulation in the fetal sacs (hydrops syndrome) and fetal overgrowth (Lee RSF et al. 2004 Biol. Reprod. 70, 1–11). Early embryonic loss in bovine NT pregnancies may also be due to immunological rejection (Hill JR et al. 2002 Biol. Reprod. 67, 55–63). As a means of overcoming placental abnormalities and improving pregnancy outcome in bovine NT, reconstructed blastocysts were produced by combining immunosurgically isolated inner cell masses (ICM) from Day 7 NT embryos with the trophectoderm (TE) of Day 7 IVF embryos. Oocytes for the production of NT and IVF embryos were obtained from abattoir-collected ovaries of dairy cows. The semen used for IVF was from the bull from which the cell line for NT was derived. The NT blastocysts were produced as described previously (Oback B et al. 2003 Cloning Stem Cells 5, 3–12) except that two one-cell embryos were aggregated together after NT (2NT). Blastocyst reconstruction was achieved using a modified procedure (Rorie RW et al. 1994 Vet. Record 135, 186–187). Embryos from four experimental groups were transferred individually to synchronized recipient heifers on Day 8 of culture: (1) ICM from 2NT embryos reconstructed with IVF TE (R-2NT, n = 15); (2) ICM from IVF embryos reconstructed with IVF TE (R-IVF, n = 15); (3) control 2NT (n = 10); and (4) control IVF (n = 10). Pregnancy rates were recorded and treatments compared using Fisher's exact test. After slaughter between Days 149 and 161 of gestation, morphometric measurements were determined for the fetuses, fetal organ weights, fluid volumes, and placentomes. Data were rank transformed; treatments were compared using Student's t-test with standard errors calculated from the pooled variation. Pregnancy rates on Day 35 were R-2NT (60%), R-IVF (47%), 2NT (90%), and IVF (10%). Pregnancy rates on Day 150 were R-2NT (40%), R-IVF (40%), 2NT (70%), and IVF (10%). The reason for the low IVF pregnancy rate was unknown. Previously, pregnancy rates using the same sire and cell line (but using Day 7 embryo transfer) on Day 35 were 63% (n = 40) and 69% (n = 42) for IVF and single, non-aggregated NT, respectively, and 50% and 33% for IVF and NT on Day 150. The single NT pregnancy rate was not significantly different from that for the 2NT embryos. There was no significant difference in pregnancy rates on Day 35 and Day 150 between R-2NT v. 2NT, R-2NT v. R-IVF, or 2NT v. R-IVF. The blastocyst reconstruction procedure did not have any impact on fetal development or influence pregnancy rates. All fetuses recovered were male. No significant differences were found between R-2NT and 2NT fetuses in terms of fetal weight, fluid volume, total placentome weight, and placentome numbers or in the relative and absolute weights of the brain, heart, liver, and kidneys. Thus, replacement of the TE in NT embryos with TE from IVF embryos did not overcome placental abnormalities or decrease fetal overgrowth prevalence.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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) | 0,001 | 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 ».