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Replication timing of 10 developmentally regulated genes in Physarum polycephalum
G Pierron1, M Benard, E Puvion
1Institut de Recherches Scientifiques sur le Cancer, Villejuif, France.
Nucleic Acids Research
|January 25, 1989
Summary
Gene expression is not limited to early replication. This study shows that some active genes in Physarum replicate late in S-phase, challenging the hypothesis that only early-replicating genes are expressed.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- The hypothesis that only early-replicating genes are expressed is widely considered.
- Understanding gene replication timing and its relation to gene activity is crucial for cell biology.
Purpose of the Study:
- To investigate the temporal order of gene replication in Physarum plasmodium.
- To test the hypothesis linking gene expression to early replication timing.
Main Methods:
- Southern analysis of density-labeled, bromodeoxyuridine-substituted DNA was used.
- Gene-dosage analysis quantified hybridization signals throughout S-phase.
Main Results:
- Four inactive genes showed varied replication timing (early, mid, and late S-phase).
- Four of six active genes replicated early in the S-phase.
- Two active genes were surprisingly found to replicate late in S-phase, with one pinpointed at 80-85% genome duplication.
Conclusions:
- Late replication during S-phase does not preclude gene activity.
- The study challenges the established hypothesis regarding gene expression and replication timing.