Live-Imaging of Axonal Cargoes in Drosophila Brain Explants Using Confocal Microscopy

Live-imaging of axonal cargoes within central nervous system has been a long-lasting interest for neurobiologists as axonal transport plays critical roles in neuronal growth, function, and survival. Many kinds of cargoes are transported within axons, including synaptic vesicles and a variety of membrane-bound and membrane-less organelles. Imaging these cargoes at high spatial and temporal resolution, and within living brains, is technically very challenging. Here, we describe a quantitative method, based on customized mounting chambers, allowing live-imaging of axonal cargoes transported within the maturing brain of the fruit fly, Drosophila melanogaster. With this method, we could visualize in real time, using confocal microscopy, cargoes transported along axons. Our protocol is simple and easy to set up, as brains are mounted in our imaging chambers and ready to be imaged in about 1 h. Another advantage of our method is that it can be combined with pharmacological treatments or super-resolution microscopy.