CRYOPRESERVATION OF THE CONCHOCELIS OF PORPHYRA (RHODOPHYTA) BY APPLYING A SIMPLE PREFREEZING SYSTEM

The conchocelis cells of four strains of Porphyra yezoensis Udea and f our other Porphyra species were cryopreserved in liquid nitrogen (LN) using a programmable freezer or a simple prefreezing system, which con sisted of a styrofoam box and a deep-freezer at -40 degrees C. The cel ls differed in their freezing tolerance but survived maximally when pr efrozen to -40 degrees C in a cryoprotective solution composed of 10% dimethylsulfoxide and 0.5 M sorbitol in 50% seawater. The cryopreserva tion was successfully performed by applying the simple prefreezing sys tem as well as by a programmable freezer. Conchocelis cells thawed fro m the LN temperature formed colonies and retained the ability to form conchospores that grew into gametophytic thalli. This technique using a simple prefreezing system will accelerate the spread of Porphyra cry opreservation.