FIGURE 2:

Electron microscopy of vacuolar lipid droplet internalization. Cells were grown in the absence of a nitrogen source (A, B) or for 5 h in oleic acid–containing media (C–F) and processed for electron microscopy. Both conditions lead to a stimulated internalization of LDs into the vacuole. Various stages of LD internalization are shown. Lipid droplets that enter the vacuole are partially covered by an electron-dense vacuolar membrane (B, E; higher magnification in F). These morphological characteristics suggest that LD internalization into the vacuole occurs via microautophagy in yeast. Scale bar, 1 μm.