Extraction of plasmid-like DNA and high-quality total DNA from Porphyra yezoensis

Cellls were prepared from sea snail enzyme digests of Porphyra yezoensis Thalli. Crude extracts of total DNA were isolated from Porphyra cells lysed with SDS-Proteinase K solution. Total DNA was purified with glassmilk, the resulting DNA was of high quality, could be completely digested with restriction enzymes. So that it was also suitable for analyses of Southern hybridization, RFLP and AFLP, etc. DNA bands were clearly observed in the agarose gel electrophoresis patterns of total DNAs digested with EcoRI, PstI and HaeⅢ respectively. The presence of DNA bands in the electrophoresis patterns of total DNA showed that the nuclear genome of Porphyra yezoensis may be small. Unexpectedly, a plasmid-like DNA band (2.3Kb) was found in the alectrophoresis pattern of P. Yezoensis total DNA isolated with guanidinium thiocyanate-sarcosyl solution. This is a very simple and convenient method for plasmid-like DNA isolation.