26 ASSESSMENT OF CHROMOSOME ABNORMALITIES IN SHEEP PARTHENOGENETIC AND NUCLEAR TRANSFER EMBRYOS: EFFECT OF 6-DMAP AND CYCLOHEXIMIDE ON PLOIDY
Notice bibliographique
Résumé
In current somatic cell nuclear transfer (NT) protocols, the reconstructed embryos are activated by incorporation of secondary oocyte activation compounds such as 6-DMAP or cycloheximide (CHX). The effects of these compounds on the chromosome complement of sheep NT embryos have not been studied in detail. Therefore, the aim of this study was to assess the chromosome abnormalities using sex chromosome specific probes of Day 6 blastocyst-stage sheep embryos produced from parthenogenetic activation and NT. Following 20–22 h of IVM, the oocytes were activated by electric pulsing followed by 30-min culture in cytochelasin B. They were reactivated using ionomycin (5 min) followed by 2-h culture in 6-DMAP or CHX. In contrast, NT embryos were produced using standard NT procedures using male sheep fetal fibroblasts. Reconstructed embryos were activated using the same methods described earlier. The embryos (compact morulae and blastocysts) were fixed and subjected to FISH analysis using cattle X and Y chromosome painting probes. The data were analyzed using Fisher's exact test. Of the parthenogenetic embryos (6-DMAP, n = 28; CHX, n = 32) analyzed, none of the embryos was totally haploid (X) or totally polyploid. When all of the nuclei per embryo were considered, normal (XX) genotype embryos were 6.2% and 0.0% in CHX and 6-DMAP groups, respectively. The rest of the embryos were abnormal due to mixoploidy (100% vs. 93.8%, P < 0.05) in 6-DMAP and CHX treatment groups, respectively. The abnormal nuclei per embryo ranged from 7.3% to 72.2%. The mean total cell number of parthenogenetic blastocysts was 91.2 ± 4.3 and 81.8 ± 6.2 (mean ± SE) in 6-DMAP and CHX, respectively. Among NT embryos analyzed, (6-DMAP, n = 30; CHX, n = 32) only 40.0% and 43.8% of embryos were completely normal for XY chromosomes in 6-DMAP- and CHX-treated groups, respectively. The rest of the embryos were abnormal due to mixoploidy (60.0% vs. 56.2%, P > 0.05) in 6-DMAP and CHX groups, respectively. Monosomy (XO or OY), trisomy (XXY), and tetrasomy (XXYY) were the common abnormalities detected in mixoploid embryos. The abnormal cells per embryo ranged from 3.8% to 41.8% in both treatment groups. The mean total cell number of NT blastocysts was 71.2 ± 9.8 and 63.8 ± 8.4, in 6-DMAP and CHX treatment groups, respectively. In conclusion, the 6-DMAP-treated embryos derived from parthenogenetic activation had significantly higher chromosomal abnormalities than CHX-treated embryo groups (P < 0.05). In contrast, the NT embryos derived from either 6-DMAP or CHX treatment did not show any significant difference in producing chromosomally abnormal embryos at the blastocyst stage. This study also highlights the feasibility of using bovine chromosome painting probes on ovine embryo spreads. This work was supported by NSERC, OMAFRA, and ICCS.
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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) | 0,001 | 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 ».