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Updated: Aug 12, 2026
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CAPRRESI: Chimera Assembly by Plasmid Recovery and Restriction Enzyme Site Insertion
Published on: June 25, 2017
Rapid screening for plasmid DNA
Molecular & General Genetics : MGG
|March 7, 1977
Summary
This study presents a method for visualizing plasmid DNA and determining its molecular weight using neutral sucrose gradient centrifugation and ethidium bromide fluorescence. The technique allows for the separation and identification of different plasmid forms based on their sedimentation properties.
Area of Science:
- Molecular Biology
- Biochemistry
Background:
- Plasmid DNA is crucial in molecular biology and genetic engineering.
- Accurate determination of plasmid DNA molecular weight is essential for various applications.
Purpose of the Study:
- To describe a reliable procedure for demonstrating plasmid DNA and its molecular weight.
- To enable visualization of DNA species through fluorescence.
Main Methods:
- Rate zonal centrifugation of unlabelled DNA in neutral sucrose gradients.
- Incorporation of a low concentration of ethidium bromide in the gradients.
- Visualization of DNA bands using ultra-violet light.
Main Results:
- Each DNA species forms a discrete fluorescent band, allowing for visualization.
- Closed circular and relaxed circular plasmid DNA molecules sediment separately.
- During lysate preparation, closed circular molecules are nicked, resulting in a single band of relaxed circles for each plasmid.
Conclusions:
- The described method effectively demonstrates plasmid DNA and its molecular weight.
- The technique provides a reliable way to visualize and differentiate plasmid DNA forms.
- This procedure is valuable for molecular biology research involving plasmid analysis.
