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Short-term rescue by RNA injection of a mitotic arrest mutation that affects the preimplantation mouse embryo
Abstract:
The mutation oligosyndactyly results in syndactyly, abnormal fusion and insertion of certain limb muscles, and diabetes insipidus in heterozygous mice. When homozygous the mutation is lethal; beginning at the blastocyst stage, the homozygous cells arrest in metaphase with intact spindles. The mutant phenotype cannot be corrected by forming aggregation chimeras with wild-type cells, suggesting that the mutation results in a cell autonomous lethal condition. Short-term rescue of the homozygous-induced mitotic arrest can be achieved, however, by cytoplasmic injection of polyadenylated RNA obtained from a rapidly dividing embryo-derived stem cell line.
Insights
The oligosyndactyly mutation causes limb and kidney defects in mice. Homozygous mutations are lethal at the blastocyst stage due to cell cycle arrest, indicating a cell-autonomous condition.
Area of Science:
- Developmental Biology
- Genetics
- Cell Biology
Background:
- The oligosyndactyly (Ols) mutation in mice presents with syndactyly, abnormal muscle development, and diabetes insipidus in heterozygotes.
- Homozygous Ols mutations are embryonically lethal, arresting at the blastocyst stage.
Purpose of the Study:
- To investigate the cellular basis of the embryonic lethality associated with the oligosyndactyly mutation.
- To determine if the homozygous mutant phenotype is cell-autonomous.
Main Methods:
- Analysis of homozygous mutant embryos at the blastocyst stage.
- Formation of aggregation chimeras between wild-type and homozygous mutant cells.
- Cytoplasmic injection of RNA into homozygous mutant cells.
Main Results:
- Homozygous Ols mutant cells arrest in metaphase with intact mitotic spindles.
- Aggregation chimeras with wild-type cells did not rescue the homozygous mutant phenotype, confirming cell autonomy.
- Transient rescue of the mitotic arrest was achieved by injecting polyadenylated RNA from embryonic stem cells.
Conclusions:
- The oligosyndactyly mutation causes a cell-autonomous lethal condition during early mouse development.
- The lethality is linked to a failure in cell cycle progression at metaphase.
- RNA-mediated rescue suggests a requirement for specific gene products essential for mitosis.