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 diacylglycerolupon a downward shift in temperature was studied under variousconditions in Anabaena variabilis. The following conclusionsare drawn from the experimental results. (1) The desaturationof palmitic to palmitoleic acids after the temperature shiftfrom 38 to 22°C occurs in the dark as well as in the light.The desaturations of oleic to linoleic and of linoleic to linolenicacids after the temperature shift are stimulated by illumination.(2) The C₁₆ and C₁₈ acids are desaturated to different degreesdepending on the magnitude of the temperature shift. (3) Thedesaturations require molecular oxygen. (4) Syntheses of RNAand proteins are involved in the mechanism for the temperatureshift-induced desaturation of fatty acids. (Received May 27, 1981; Accepted July 7, 1981)