| Popis: |
A procedure for the isolation of the plasma membranes from zoospores of Blastocladiella emersonii , which involves the rupturing of the plasma membrane, is described. The ultrastructural organization of the zoospore then permits the removal of the major cytoplasmic organelles as a single unit. Analysis of the membrane lipids indicated that the membrane is composed of glycolipids and neutral lipids, rather than phospholipids. The glycolipid fraction contained only diglycosyldiglycerides, and ≅ 90% of the glycolipid head groups were glucose, indicating that diglycosyldiglycerides comprise the largest single group of lipids in the plasma membrane preparations (≅ 47% of total lipid by weight). The membrane preparation was also characterized by the absence of triglycerides, although it did contain sterols. The preponderance of glycolipids in the plasma membrane preparations can account for the physical-chemical changes previously observed in zoospore plasma membranes in vivo , and in isolated plasma membrane preparations. The presence of glycolipids in both the plasma membrane and γ-particles, which directly interact with each other, via vesicle fusion, to form the chitinous cell wall, and the biochemical role of glycolipids in chitin synthesis in this organism suggest that the glycolipids may be involved in the regulation of zoospore encystment. |
