Abstract
BY-2 cells transformed with a cytochrome B5 - red fluorescent protein fusion construct (CytB5-RFP). This protein distributed in the log-phase cells as punctate pattern. Upon reaching to the stationary phase, some of the RFP fluorescence was detectable in the lumen of the vacuole. To address what is the trigger of such the relocation of CytB5-RFP at the stationary-grown cells, we incubated the CytB5-RFP expressing cells at log phase in media with different composition. The result was that sucrose-free medium caused the relocation of RFP fluorescence into the vacuole. When the cysteine protease inhibitor was present in the starvation medium, the relocation of CytB5-RFP was blocked. These findings suggest that BY-2 cells have a mechanism to sense the amount of the nutrient in the medium and also suggest that the cells upon starvation activate a mechanism to transfer cytosolic organelles to the vacuole for degradation.
