CRYOPRESERVATION OF THE GAMETOPHYTIC CELLS OF LAMINARIALES (PHAEOPHYTA) IN LIQUID NITROGEN

The gametophytic cells of six species of Laminariales, Laminaria japonica Areschoug, L. longissima Miyabe, Kjellmaniella crassifolia Miyabe, Ecklonia stolonifera Okamura, E. kurome Okamura, and Undaria pinnatifida (Harvey) Suringar, were subjected to cryopreservation in liquid nitrogen. The cells were suspended in various cryoprotective solutions and slowly cooled to -40 degree C over a period of 4 h. After this slow cooling step, the suspensions were immediately immersed in liquid nitrogen. All the species of Laminariaceae used in the present study survived maximally in a mixture of ethylene glycol and proline. On the other hand, the gametophytic cells of Undaria pinnatifida, a member of the Alariaceae, survived maximally in the mixture of glycerol and proline. The viability of the thawed gametophytic cells decreased during postthawing incubation. The decrease in viability continued for 4-6 days, and the minimum levels ranged from 36.2% to 67.2%. After 4-6 days of incubation, the percentage viability of all strains began to increase due to the renewal of cell division.