51 DEVELOPMENT OF BOVINE CLONES CONSTRUCTED WITH CYTOPLASM ORIGINATING FROM OOCYTES CULTURED IN RETINOL
Notice bibliographique
Résumé
Incomplete reprogramming of a somatic nucleus by the oocyte cytoplasm may contribute in large part to inefficiencies of cloning procedures using somatic cell nuclear transfer. Predominant use of cytoplasts derived from in vitro-matured oocytes may further exacerbate problems. Addition of all-trans-retinol (Livingston TL et al. 2002 Biol. Reprod. 66, 104–105 abst) or 9-cis-retinoic acid (Duque P et al. 2002 Human Reprod. 17, 2706–2714) to culture medium improved developmental competence of oocytes to blastocyst stage. The objective of this study was to evaluate effects of retinol for improving developmental competence of cloned embryos constructed with retinol-treated cytoplasts. After removal from 3–8 mm follicles, COC were matured in the presence of 0 (n = 1005; diluent only) or 5 µM all trans-retinol (n = 1017). Beginning approximately 18 h after placement into culture, oocytes with extruded polar bodies were enucleated of maternal chromatin. Ovarian/granulosa cells were aspirated from adult Jersey cows (n = 2) using an ultrasound-guided transvaginal probe. Primary cell lines were established and, before nuclear transfer, cultured in the presence of 0.5% serum (5–8 days; passage = 3). Ovarian/granulosa cells were fused with cytoplasts originating from control or retinol-treated oocytes using two electrical pulses of 2.2 kV cm-1 for 20 µs between 24–27 h post-maturation (hpm). Cloned embryos were activated between 26.5 and 30 hpm and then cultured in an atmosphere of 7% O2 and 5.5% CO2 in KSOMaa + BSA. Development of cloned embryos to morula and blastocyst stages was assessed on Days 6–7 post-activation. In 5 replicates, compact morulae and blastocysts were transferred to synchronous recipients. Establishment of pregnancy was confirmed 28 days post-estrus by presence of an embryonic heartbeat using ultrasound. With the exception of pregnancy, data were analyzed as a randomized block design using mixed models of SAS (2000) after testing for normality. Proportion of oocytes recovered after denuding (94.5 and 88.9%; SEM = 2.2), those that had visibly lysed (6.4 and 7.3%; SEM = 1.5), and extruded a polar body by 20 hpm (61.7 and 62.5%; SEM = 7.0) was similar for control and retinol-treated oocytes, respectively. In addition, ability of ovarian/granulosa cells to fuse with control or retinol-treated cytoplasts was similar (80.6 and 73.1%; SEM = 4.5). Lysis of cytoplasts after electrical pulses (8.2 v. 13.6%; SEM = 3.3) and activation (11.6 v. 5.0%; SEM = 2.9) did not differ for control and retinol-treated cytoplasts. Development to morula and blastocyst stages was lower in cloned embryos constructed with retinol-treated cytoplasts (Table). However, ability of morulae and blastocysts to establish a pregnancy was comparable. One clone from each treatment developed to term and was born alive. Culture of oocytes in medium containing retinol during maturation did not improve developmental competence of clones.
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) | 0,000 | 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 ».