Determination of plasmid copy number by fluorescence densitometry

Plasmid. 1983 Mar;9(2):182-90. doi: 10.1016/0147-619x(83)90019-7.


A simple and reliable method for the determination of plasmid copy numbers by direct fluorescence densitometry of ethidium bromide-stained electrophoretic gels was developed. In developing the method, the following parameters were evaluated and controlled: plasmid DNA trapping in the linear chromosomal DNA, staining-destaining kinetics for ethidium bromide, linearity of the fluorescence response, and the effect of the molecular topology of DNA on ethidium bromide binding to DNA in agarose.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • DNA, Bacterial / genetics
  • Densitometry / methods*
  • Electrophoresis, Agar Gel
  • Ethidium
  • Fluorescence
  • Gene Amplification
  • Genetic Techniques*
  • Nucleic Acid Conformation
  • Plasmids*
  • Staphylococcus aureus / genetics


  • DNA, Bacterial
  • Ethidium