Plasmid deoxyribonucleic acid in Rhizobium trifolii
Journal of Bacteriology
|October 1, 1976
Summary
Researchers identified a covalently closed circular deoxyribonucleic acid (DNA) plasmid in Rhizobium trifolii. This plasmid, detected via cesium chloride-ethidium bromide equilibrium centrifugation, has a molecular weight of approximately 64 x 10^6.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Rhizobium trifolii is a nitrogen-fixing bacterium crucial for legume symbiosis.
- Characterization of extrachromosomal DNA elements like plasmids is vital for understanding bacterial genetics and function.
Purpose of the Study:
- To isolate and characterize plasmid deoxyribonucleic acid (DNA) from Rhizobium trifolii.
- To determine the molecular weight and structural properties of the identified plasmid.
Main Methods:
- Cesium chloride-ethidium bromide equilibrium density gradient centrifugation was used to separate DNA components.
- Sedimentation analysis in sucrose gradients and transmission electron microscopy were employed for molecular weight determination and visualization.
Main Results:
- A satellite peak containing covalently closed circular deoxyribonucleic acid (DNA) was detected during centrifugation.
- The isolated plasmid deoxyribonucleic acid (DNA) exhibited a molecular weight of approximately 64 x 10^6 Daltons.
Conclusions:
- Rhizobium trifolii harbors a distinct covalently closed circular deoxyribonucleic acid (DNA) plasmid.
- The characterized plasmid is a significant extrachromosomal element within this bacterial species.
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