5 NEUTRAL SEGREGATION OF DONOR CELL MITOCHONDRIA IN FETAL AND ADULT TISSUES OF SOMATIC CELL CLONES IN CATTLE
Notice bibliographique
Résumé
Until now, animal cloning has been extremely inefficient: only 1–2% of nuclear transfer (NT) clones survive to birth. Some of these anomalies may be related to an incompatibility between nuclear and mitochondrial genes (Cummins JM 2001 Hum. Reprod. Update 7, 217–228). Controversy exists as to the levels of donor cell mitochondrial DNA (mtDNA) inheritance in somatic clones (heteroplasmy). Whereas some researchers found very low quantities (0.1–4%) (Steinborn R et al. 2000 Nat. Genet. 25, 255–257), others found levels of heteroplasmy ranging from 6 to 40% (Takeda et al. Mol. Reprod. Dev. 64, 429–437). Since it remains unclear whether mtDNA segregation is neutral or selective, the purpose of this study was to analyze the transmission of the mtDNA from donor somatic cells in fetal and adult clones using a particular mtDNA marker (mtDNA Bos taurus with one mutation in the D-loop of 40 base pairs plus than the wild type). Fibroblasts from a fetus of 60 days were used as donor cells. The fetus was produced by artificial insemination of a Holstein (Bos taurus) heifer carrying an mtDNA mutation with semen from a Zebu (Bos indicus) bull. Oocytes derived from slaughterhouse ovaries of Holstein cows carrying wild-type mtDNA were used as recipient cells. The presence of the mutated mtDNA from the donor cell (heteroplasmy) was analyzed in a male cloned fetus of 60 days and in three adult male clones at 18 months of age. Heteroplasmy was detected in 7 tissues in the foetus: muscle, skin, stomach, testicle, thymus, tongue, and umbilical cord. Three tissues were analyzed from the adult clones: semen, skin, and white blood cells. Heteroplasmy was detected in all the tissues by nested PCR amplification of the D-loop and analyzed by ANOVA and Tukey-Kramer multiple comparison test. The mean (%) of the mutated mtDNA of the donor cell in the seven tissues of the 60-day-old fetus was 1.14 ± 0.34 (SEM). There was no differences in the means of heteroplasmy (%) between the tissues of the fetus (P > 0.05). The mean level of heteroplasmy in the three adult clones analyzed (clones A, B, and C) was 1.41 ± 0.18 (SEM). Analysis of heteroplasmy between the tissues of each clone showed no differences (P > 0.05) with the exception of clone B, where semen was different (P < 0.05) from white blood cells. There were significant differences (P < 0.05) between some clones (taking together all the results of all tissues of each clone). The heteroplasmy in clone B (%) (2.59 ± 0.18 SEM) was different (P < 0.05) from that of both clone A (1.04 ± 0.18) and clone C (1.46 ± 0.18). There was no difference between the heteroplasmy (%) of clone A and that of clone C (P > 0.05). These results show that the tissues of the fetus and the adult clones were heteroplasmic at similar levels, suggesting neutral segregation of the donor cell mtDNA during development and tissue differentiation.
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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 | 0,000 | 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 ».