Protoplasts from Acetabularia: isolation and fusion.

Protoplasts were isolated from cells of Acetabularia cliftonii, which are presumed to be haploid. The release of the protoplasts occurred after treatment of the cells with papain or proteinase K. They are genuine protoplasts since they contain a nucleus. Fusion was initiated by mechanically pushing together two protoplasts. Under these conditions, the efficiency of fusion was more than 90% within 30 minutes at room temperature. Haploid cells from one cyst, i.e., cells which eventually would have formed gametes of the same mating type, exhibit a greater propensity for fusion as compared to haploid cells from different cysts.