title: Photosynthetic Activities of the Halophilic Alga Dunaliella parva.
abstract: Dunaliella parva, a unicellular halophilic alga, was found to evolve oxygen photosynthetically only in the presence of a high osmolar concentration. Cell free preparations were obtained by placing the cells in a medium of low osmolarity. The fragments obtained showed a high photoreducing and photophosphorylating activity except for their inability to catalyze all ferredoxin dependent photoreactions. Placing the cells in a medium of intermediate osmolarity produced a "chloroplast" preparation which maintained some capacity for O(2) evolution and CO(2) fixation, while possessing the ability to catalyze the photoinduced reduction of ferricyanide. Enzymic and photosynthetic reactions of cell-free preparations from D. parva were inhibited, rather than stimulated, by the salt concentration optimal for growth. These results were interpreted as indicating the existence of a steep NaCl gradient in vivo between the medium and the cell compartments which are not permeable to salt.
authors.affiliation: Department of Biochemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Ben-Amotz
authors.forename: M
authors.initials: M
authors.lastname: Avron