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DNA replication in Physarum polycephalum: bidirectional replication of DNA within replicons
Nucleic Acids Research
|March 1, 1978
Summary
DNA replication in Physarum polycephalum initiates centrally within replicons and proceeds bidirectionally. This bidirectional DNA synthesis was confirmed using 5-bromouracil-deoxyriboside (BrdUrd) pulse-labeling and UV-photolysis.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Understanding DNA replication mechanisms is crucial for cell division and genetic stability.
- Physarum polycephalum, a} slime mold, offers a unique model for studying eukaryotic DNA replication.
Purpose of the Study:
- To determine the directionality of DNA replication within replicons in Physarum polycephalum.
- To identify the origin of DNA replication within these units.
Main Methods:
- Pulse-labeling of DNA with 5-bromouracil-deoxyriboside (BrdUrd) and 3H-adenosine deoxyriboside (dAdo).
- Ultraviolet (UV) -photolysis of labeled DNA.
- Analysis of single-strand DNA fragment molecular weights using alkaline sucrose gradients.
Main Results:
- Newly synthesized DNA within replicons was consistently bisected into two equal fragments upon UV irradiation.
- This fragmentation pattern occurred when BrdUrd was administered at the onset of DNA synthesis.
Conclusions:
- Replication in Physarum polycephalum replicons initiates at a central origin.
- DNA synthesis proceeds bidirectionally from this central origin in Physarum polycephalum.