• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1160-1165
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• 1998

When total cellular DNA was isolated from Porphyra tenera by ultracentrifugation on Hoechst dye/CsCl gradients method, plasmid like DNA's were concentrated at the upper band which were characterized with a A＋T rich organelle DNA's in the CsCl gradients. Based on their electrophoretic migration in different concentration of agarose gel, buffer system, and electric power etc. and the results of restriction digestion, the plasmid like DNA's were concluded to have circular conformation. This is the first report of putative circular plasmid DNA from the P. tenera, which is a autonomously replicating plasmid existing with a high copy number plasmid in the cell. The minimum size of this plasmid estimated by restriction endonuclease digestion was appeared to be 2.5kb in size.