Staining the Germline in Live Caenorhabditis elegans: Overcoming Challenges by Applying a Fluorescent-dye Feeding...

C. elegans provides a tractable model organism for studying germline cell biology. Microscopy experiments are relatively facile, as this worm is transparent and germline development can be observed in real-time using DIC microscopy and/or fluorescent transgenes. Despite these many tools, robust staining techniques for imaging germ cells in live worms have been more elusive, due to the tough outer cuticle of the worm, which impairs staining efficiency. This limitation has restricted the spectrum of probes that can be used to investigate reproductive cell biology in C. elegans. Building on previous approaches, I recently applied a fluorescent-dye feeding strategy to reproducibly label organelles and monitor physiological changes in germlines of living C. elegans. In this approach, fluorescent dyes are initially introduced into the agar plates and bacterial lawns on which worms are subsequently cultured. After worms are grown on the dyed plates, oocytes show staining patterns consistent with verified transgenic markers. Thus, this approach offers an effective solution for labeling difficult-to-stain tissues in live worms, and establishes an entry point for incorporating new probes and sensors into analyses of C. elegans germline biology.