This project seeks to clarify some of the pathways by which lipid metabolism regulates eukaryotic cell activities at the membrane level. The experiments will involve the unicellular organisms Dunaliella salina and Tetrahymena pyriformis, which have been utilized extensively as model systems for plant and animal cells, respectively. The studies will emphasize three interrelated areas: 1) regulatory mechanisms by which the "fluidity" of each functionally different membrane of a cell is maintained at a near optimal level, 2) formation and dissemination of different classes of proteins containing covalently-bound fatty acids, and 3) the control and consequences of polyphosphoinositide turnover during the transduction of extracellular signals by D. salina. Based upon preliminary findings, it seems very likely that all these three research areas are directly or indirectly related in the control of cellular function. By employing radioisotope labeling experiments and detailed analysis of membrane lipids and proteins by chromatography and electrophoresis, the biochemical pathways involved will be characterized and their regulation studied by first perturbing membrane fluidity experimentally and then observing how the control processes restore normal function. %%%% Individual key reactions of lipid metabolism are being studied in model plant systems. These reactions are also being studied not as isolated events but as how they serve the cell to provide the physical environment needed for normal cell functioning. Many reactions crucial to life take place in cellular membranes, not free in solution. This work focuses on in vivo metabolism in order to gain a realistic picture of cell metabolism in the normal state.
