UNUSUAL MEMBRANE PERMEABILITY OF 2 HALOPHILIC UNICELLULAR ORGANISMS

1. 1. The permeability of a Halobacterium species and Dunaliella parva to several radioactive substances has been measured. 2. 2. The method used was to centrifuge a cell suspension, within which was dissolved the given radioactive substance, and measure the radioactivity of the resultant cell pellet and supernatant. The volume of radioactive substance within the cell pellet was then calculated. 3. 3. Both organisms were found to be impermeable to [14C]dextran (mol. wt. 80 000). 4. 4. Results indicated that the Halobacterium cell was freely permeable to [14C]-sucrose, [14C]inulin, [14C]starch, and even [14C]polyvinylpyrollidone (mol. Wt. 30 000-40 000). 5. 5. A region of the D. parva cell was permeable to [14C]surcose and to [14C]inulin. 6. 6. It is argued that the results indicate the existence of large pores in the cell membranes of these two organisms. © 1969.