The high incidence of chromosomally abnormal human embryos is frequently assumed to be due to a lack of checkpoint controls operating during early embryogenesis. In our study we have analysed when these mechanisms first become functional. Mouse oocytes treated in late metaphase I with either of two different cyclin-dependent kinase inhibitors [butyrolactone 1 (BL1) or 6-dimethylaminopurine (6-DMAP)] form nuclei in the cytoplasm. BL1-treated eggs enter S-phase at 16-18 h post-treatment and, after completion of DNA synthesis, cleave to 2-cell stage embryos. 6-DMAP treatment results in the rapid initiation of DNA synthesis, its completion by 12 h and then arrest in the G2 phase. Thus, two different cell cycle stages can be obtained at the same time point after the initiation of treatment: G1- after BL1 and G2-staged nuclei after 6-DMAP treatment. That this approach greatly facilitates cell cycle studies has been shown by analysing checkpoint function during the first division. Whilst G2-staged eggs enter M phase within 2-3 h when 6-DMAP is washed out, the onset of M phase is delayed after their fusion to G1 (BL1) cells. Here M phase occurs only after the less advanced nucleus completes DNA replication. Our results indicate that checkpoints in mammalian eggs are functional during the first mitotic cycle.

• MeSH
• adenin analogy a deriváty   farmakologie   MeSH
• cyklin-dependentní kinasy antagonisté a inhibitory   MeSH
• DNA biosyntéza   MeSH
• G1 fáze MeSH
• G2 fáze * MeSH
• gama-butyrolakton analogy a deriváty   farmakologie   MeSH
• inhibitory enzymů farmakologie   MeSH
• mitóza * MeSH
• myši inbrední C57BL MeSH
• myši inbrední CBA MeSH
• myši MeSH
• oocyty cytologie   metabolismus   MeSH
• zvířata MeSH
• zygota MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• adenin MeSH
• butyrolactone I MeSH Prohlížeč
• cyklin-dependentní kinasy MeSH
• DNA MeSH
• gama-butyrolakton MeSH
• inhibitory enzymů MeSH
• N(6),N(6)-dimethyladenine MeSH Prohlížeč