Studies on the Temperature Shift-induced Desaturation of Fatty Acids in Monogalactosyl Diacylglycerol in the Blue-green Alga (Cyanobacterium), Anabaena variabilis

The desaturation of fatty acids in the monogalactosyl diacylglycerol upon a downward shift in temperature was studied under various conditions in Anabaena variabilis. The following conclusions are drawn from the experimental results. (1) The desaturation of palmitic to palmitoleic acids after the temperature shift from 38 to 22°C occurs in the dark as well as in the light. The desaturations of oleic to linoleic and of linoleic to linolenic acids after the temperature shift are stimulated by illumination. (2) The C16 and C18 acids are desaturated to different degrees depending on the magnitude of the temperature shift. (3) The desaturations require molecular oxygen. (4) Syntheses of RNA and proteins are involved in the mechanism for the temperature shift-induced desaturation of fatty acids.