A model of BODIPY and Nile Red trafficking in live wild-type animals and peroxisomal β-oxidation mutants. (A) A schematic diagram of possible BODIPY (green) and Nile Red (red) trafficking in gut epithelial cells in wild-type animals. A single gut epithelial cell is diagrammed as a rectangular box with microvilli (triangles) pointing to the gut lumen. Gut epithelial cells are rich in vesicular structures, which include LROs (orange vesicles), lipid droplets (green vesicles labelled as LD), and other vesiclular organelles (white). Both BODIPY and Nile Red are endocytosed into the gut epithelial cell and trafficked through endolysosomal pathways to LROs (orange arrow and orange vesicles). Hypothetically, BODIPY can be targeted to lipid droplets from LROs and or from endosomes (green arrows question marked). (B) In peroxisomal β-oxidation mutants, lipid droplet size increases (large orange vesicles). Nile Red as well as BODIPY can be targeted to lipid droplets (orange arrows question marked).