The role of algal antigenic determinants in the recognition of potential algal symbionts by cells of Chlorohydra.

Algal cells grown in the green hydra Chlorohydra viridissima were shown to possess characteristic antigenic determinants not found in algae cultured in vitro. These antigenic determinants, including those localized on the algal cell surface, were shown to be responsible for the phagocytic recognition of potential algal symbionts by digestive cells of Chlorohydra. The results of this study indicate the existence of two systems governing phagocytosis in Chlorohydra, one specific for algal cells grown in hydra, another governing the uptake of other particles by the hydra digestive cells.