Abstract
Cells degrade their constituents in response to various nutrient starvation stresses. Degradation products are used for the synthesis of new cellular constituents and for obtaining energy. Autophagy, one of the self-degradation mechanisms, has been known to be responsible for the degradation of proteins under nutrient starvation conditions. Cells also degrade phospholipids, the main component of cell membranes, but we have shown that autophagy is not a main contributor to the degradation of phospholipids in cultured tobacco BY-2 cells.
In order to better understand phospholipid degradation, we had BY-2 cells uptake a fatty acid analog labeled by the fluorochrome BODIPY. Then we observed the BODIPY fluorescence by fluorescence microscopy, and measured the fluorescence in the lipid fractions extracted from the cells. The results suggested 80 % of phospholipids are degraded within 24 hours and the degradation products of phospholipids accumulate in vacuoles. We are now trying to identify the degradation product(s) of phospholipids accumulating in vacuoles. In this presentation, we will report the results and discuss the involvement of the central vacuoles in phospholipid degradation.
