CHANGES OF THE COMPOSITION OF PHOSPHOLIPIDS, FATTY-ACIDS AND CHOLESTEROL FROM THE ERYTHROCYTE PLASMA-MEMBRANE FROM FLOUNDERS (PLATICHTHYS-FLESUS L) WHICH WERE ACCLIMATED TO HIGH AND LOW-TEMPERATURES IN AQUARIUMS

1. The composition of the plasma membrane from flounder has been deter mined with respect to protein, cholesterol, phospholipids and fatty ac ids from a total lipid extract and from phosphatidyl choline and phosp hatidyl ethanolamine. The composition was determined after the flounde rs had been acclimated to 2.5 or to 20-degrees-C. 2. The composition o f the membranes, with respect to individual phospholipids, is not affe cted by the change of temperature, whereas the amount of cholesterol i s larger in the warm-adapted flounder membranes than in the cold-adapt ed ones. 3. The composition of fatty acids from a total lipid extract, and from phosphatidyl choline and phosphatidyl ethanolamine, varies a ccording to the temperature of acclimation. 4. It is shown that the ob served variations of the composition of lipids are the result of a phy siological adaptation induced by changes in temperature.