Imaging lipid droplet fusion in NIH-3T3 cells.

(a) Bodipy493/503 stained MEFs were imaged using time-lapse fluorescent z-stack confocal microscopy for 30 min. Tracking of the LDs using Imaris software demonstrated that the LDs underwent little directional motility. Tracks are shown through time from blue to white. Bar = 5 µm. (b) Images of Bodipy493/503 stained NIH-3T3s were deconvolved to increase the resolution of individual LDs. Bar = 10 µm. (c) 3D rendering of Bodipy493/503 stained LDs in close proximity can produce a single entity (arrows). Bar = 1 µm. (d) 50% of the LDs in NIH-3T3s are found in clusters (arrows). Bar = 10 µm. (e) Examples of juxtaposed LDs (yellow) which appear to fuse and have a spherical profile as viewed in the x–y plane of rendered LDs but have a highly irregular profile in the x–z plane. Bar = 1.5 µm. (f) The appearance of a ‘waist-like’ structure between two rendered LDs in the x–z and x–y planes is absent when viewed in a single unrendered x–y plane. Bar = 1 µm. N = nuclei.