Fatty acid metabolism in the chloroplast lipids of green and blue-green algae.

The pattern of uptake of radioactivity into chloroplast lipids when a green alga (Chlorella vulgaris) was incubated with sodium 2-(14)C-acetate differed appreciably from that obtained when two blue-green algae (Anabaena cylindrica andAnacystis nidulans) were incubated under similar conditions.The fatty acids of the digalactosyl diglyceride and sulphoquinovosyl diglyceride fractions from the blue-green algae were labeled more rapidly than were those of the corresponding fractions fromC. vulgaris, whereas the activity in the acids of the phosphatidyl glycerol fraction fromA. cylindrica andA. nidulans was relatively lower than that in the green alga. The results indicate that the metabolic behavior of chloroplast lipids may vary considerably according to the class of alga concerned.In all three alga, the evidence points to an intermediary function for the chloroplast lipids in fatty acid synthesis.Only limited exchange of acyl groups between the different chloroplast lipids seemed to occur during photoautotrophic growth.