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Control of first cleavage in single-cell reconstituted mouse embryos
L C Smith1, I Wilmut, J D West
1AFRC, Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, Roslin, Midlothian, UK.
Journal of Reproduction and Fertility
|March 1, 1990
Summary
Early mouse embryo nuclei can synchronize with later cytoplasm, but late nuclei cannot advance cell division timing. Incompatible interactions can cause developmental arrest, highlighting critical nucleo-cytoplasmic timing in early embryogenesis.
Area of Science:
- Developmental Biology
- Cell Biology
- Embryology
Background:
- Understanding nucleo-cytoplasmic interactions is crucial for early embryonic development.
- The timing of cell cycle progression is tightly regulated by both nuclear and cytoplasmic factors.
Purpose of the Study:
- To investigate the regulatory roles of nuclear and cytoplasmic factors in early mouse embryonic cell division.
- To assess the compatibility of nuclei and cytoplasm from different cell cycle stages in reconstituted embryos.
Main Methods:
- Fusion of karyoplasts from early/late mitotic interphase mouse embryos to enucleated 1-cell embryos.
- Monitoring cleavage times of reconstituted and control embryos at hourly intervals.
- Analyzing nuclear-cytoplasmic interactions and their impact on cell cycle progression.
Main Results:
- Early nuclei could synchronize with late cytoplasm, causing only a minor delay in cleavage.
- Late nuclei failed to advance cleavage timing in early cytoplasm, leading to prolonged interphase.
- Reconstituted embryos with late 2-cell nuclei and early 1-cell cytoplasm frequently arrested in interphase.
Conclusions:
- Early embryonic nuclei can adapt to later cytoplasmic timing, likely requiring DNA synthesis completion.
- Late embryonic nuclei cannot override cytoplasmic cell cycle timing, leading to developmental blocks.
- Incompatible nucleo-cytoplasmic interactions are critical determinants of developmental success in early mouse embryos.