RNAi of lipid droplet associated genes was performed for either the
“full lifetime”, from synchronized L1 animals, or “delayed start”, from
approximately 24 h past L1 when worms were washed and transferred
to RNAi plates. All animals were allowed to grow to the young adult
stage on RNAi plates and fixed Nile red staining was performed in a similar
manner as described [33]. Nematodes were washed with PBS with
0.01% triton X-100 in a microcentrifuge tube. The supernatant was removed
and animals were fixed with 150 μl of 40% isopropanol at room
temperature for 3 min. The supernatant was removed manually, leaving
25 μl 40% isopropanol and worm pellet. To each sample 150 μl of freshly
prepared Nile red staining solution (6 μl Nile red stock solution of
0.5 mg/ml in acetone per 1 ml of 40% isopropanol) was added and the
tubes resealed and gently shaken in the dark for at least 2 h. Samples
were allowed to settle by gravity and all but 25 μl of Nile red dye was removed
and washed with 1 ml of M9 buffer. Worms were mounted on
slides and imaged by fluorescent microscopy using a GFP/FITC filter.
All RNAi Nile red staining experiments were performed in triplicate
and blindly scored by at least two different individuals to assess alterations
in fat accumulation. Images for publication were viewed with
laser excitation at 488 and filtered at 495/535 nm (GFP excitation/emission)
and imaged on a Leica TCS SP5 confocal microscope with a 63× oil
immersion lens. Images were processed identically using Adobe
Photoshop CS4.