Abstract:
Erythrocytes of the freshwater fish (Cypnnus carpio) adapted to 22 degrees C were exposed either to 30 degrees C or 10 degrees C for 2 hr and the temperature dependency of fluorescence polarization of 1,6- diphenyl 1,3,5- hexatriene, embedded into isolated plasma membranes, mitochondrial membranes and microsomal membranes was determined. Fluorescence polarization of phospholipid vesicles prepared from erythrocytes of summer and winter adapted carps was also studied. There was roughly a 20 percent compensation for temperature when assaying the phospholipid vesicles. Exposure of cells in vitro to 10 degrees C resulted in a decrease of fluorescence polarization of the separated membranes alongwith an enhancement of delta 9 and delta 6 desaturation in microsomal membranes. The effect is just reverse when the cells were exposed to 30 degrees C. Thus there is a clear indication of active adaptation in the physical state of the membranes to the prevailing temperature. Possible role of the unsaturated fatty acid in controlling membrane physical properties is discussed.
