Low-temperature-induced changes in intracellular fatty acid fluxes in Dunaliella salina.

Two-minute exposures to exogenous [14C]palmitic, [14C]oleic, or [14C]lauric acid differentially labeled the lipids of Dunaliella salina microsomes and chloroplasts. Changes in fatty acid desaturation and intracellular movement during a subsequent 16-h incubation in nonradioactive medium indicated a slow transfer of lipids into the chloroplast from other organelles. Since Dunaliella lacks the massive traffic of microsomally produced glycerolipids into chloroplast galactolipids that dominates chloroplast-microsome lipid relations in most plant cells, it affords a sensitive system for studying more subtle intracellular lipid fluxes. Lowering the culture temperature from 30 to 12 degrees C was more inhibitory toward glycerolipid biosynthesis in chloroplasts than in microsomes. The ability of Dunaliella chloroplasts to utilize microsomal lipids may be essential for their systematic acclimation to low temperature.