Lysosomes appear as the auto-fluorescent vacuoles in Dictyostelium discoideum cells

Abstract

Dictyostelium discoideum cells contain auto-fluorescent vacuoles. To determine the identity of these vacuoles, the fluorescent dye 4-nitro-7-(1-piperazinyl)-2,1,3-benzoxadiazole (NBD-PZ) was used to stain the lysosomes in D. discoideum cells. Neither the auto-fluorescent vacuoles nor lysosomes were observed in D. discoideum cells immediately after they arose from spores or in stationary phase cells. However, both the auto-fluorescent vacuoles and lysosomes were visible in cells that had entered growth phase. Auto-fluorescent vacuoles and lysosomes were also observed in stationary phase cells incubated with chloroquine. When the cells were allowed to phagocytose BioParticles Fluorescent Bacteria (orange fluorescence) for 1 h, orange phagosomes and blue auto-fluorescent vacuoles were observed as independent moieties. However, after an additional 2 h of incubation, we observed vacuoles with mixed fluorescence (orange and blue) in the cells, suggestive of secondary lysosomes. These results suggest that the auto-fluorescent vacuoles in D. discoideum cells are lysosomes.

Keywords

• auto-fluorescence
• chloroquine
• dictyostelium
• lysosome
• nbd-pz