Abstract
Gut granules are prominent cytoplasmic organelles that auto fluoresce when excited by much of the visible spectrum confounding fluorescence imaging of endogenous fluorescent reporters. We report a simple, chemical-free fixation method for C. elegans that preserves non-cytoplasmic GFP localization for months while nearly eliminating intestinal autofluorescence. To illustrate the utility and limitations of the method, we present representative images of live and heat-fixed worms expressing a variety of membrane and non-membrane localized GFP reporters expressed in diverse tissues, cells, and cellular organelles. We also describe our experience with various experimental parameters. The observed variability of non-membrane-anchored reporters suggests prudent adopters should empirically interrogate the signal fidelity of their specific reporters upon heat fixation.