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Updated: Aug 11, 2026

Agarose Gel Electrophoresis for the Separation of DNA Fragments
Published on: April 20, 2012
Ethidium DNA agarose gel electrophoresis: how it started
1Division of Molecular Biology, Centre of Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands. p.borst@nki.nl
Abstract:
We started ethidium DNA agarose gel electrophoresis when our ultracentrifuge broke down and we needed an alternative method to check the quality of our mitochondrial DNA preparations. Agarose proved convenient for sizing DNA; ethidium in gel and buffer allowed visualization of DNA bands immediately after the run and improved the separation of the closed and open duplex forms of mitochondrial DNA circles. At smaller gel pore size mitochondrial DNA circles were excluded from the gel, whereas long linear DNAs were not. We concluded that the linear DNAs 'crawl like snakes head on through the gel'. This paper reviews some of the early experiments preceding the introduction of ethidium agarose gel electrophoresis.
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