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Mitochondrial DNA replication but no nuclear DNA replication during development of Dictyostelium
1Department of Biology, University of California at San Diego, La Jolla 92093, USA.
Abstract:
Dictyostelium discoideum cells initiate development when nutrients are depleted. DNA synthesis decreases rapidly thereafter but resumes during late aggregation, only in prespore cells. This observation has been previously interpreted as indicating progression of prespore cells through the cell cycle during development. We show that developmental DNA replication occurs only in mitochondria and not in nuclei. We also show that the prestalk morphogen known as differentiation-inducing factor 1 can inhibit mitochondrial respiration. A model is proposed for cell type divergence, based on competition to become prespores, that involves mitochondrial replication in prespore cells and reduction of mitochondrial activity in prestalk cells.
Insights
During Dictyostelium discoideum development, DNA replication occurs in mitochondria, not nuclei, particularly in prespore cells. Differentiation-inducing factor 1 impacts mitochondrial respiration, suggesting a model for cell type divergence.
Area of Science:
- Cellular biology
- Developmental biology
- Molecular biology
Background:
- Dictyostelium discoideum initiates development upon nutrient depletion.
- Previously, DNA synthesis during development was thought to indicate cell cycle progression in prespore cells.
Purpose of the Study:
- To investigate the location and nature of DNA synthesis during Dictyostelium discoideum development.
- To explore the role of differentiation-inducing factor 1 in cellular differentiation and mitochondrial activity.
Main Methods:
- Analysis of DNA replication in nuclei versus mitochondria during development.
- Assessment of differentiation-inducing factor 1's effect on mitochondrial respiration.
Main Results:
- Developmental DNA replication was confirmed to occur exclusively in mitochondria, not nuclei.
- Differentiation-inducing factor 1 was found to inhibit mitochondrial respiration.
- Mitochondrial replication in prespore cells and reduced mitochondrial activity in prestalk cells were observed.
Conclusions:
- Cell type divergence in Dictyostelium discoideum may involve competition for prespore fate.
- This competition is linked to differential mitochondrial activity: replication in prespore cells and reduced activity in prestalk cells.