Lipids of membranes and of the cell envelope in heterocysts of a blue-green alga.

Heterocysts of Anabaena cylindrica, isolated rapidly in the cold, were found-in contrast to earlier reports-to contain all of the same lipids and lipophilic pigments, and in about the same proportions, as vegetative cells. In broken filaments and in heterocysts damaged during isolation, the membrane lipids and certain pigments (myxoxanthophyll and an unidentified red pigment) break down rapidly. The glycolipids specific to heterocyst-forming blue-green algae are localized in the laminated layer of the heterocyst envelope. A possible role of the laminated layer is discussed.