Visualizing the Intracellular Trafficking in Zebrafish Mauthner Cells.

Axonal transport is crucial for the development and survival of neurons and maintenance of neuronal function. Disruption in this active process causes diverse neurological diseases. Thus, study of the intracellular trafficking as one way to gain the knowledge of the kinetics of axonal transport is essential to understand the mechanisms underlying the neuropathology. A lot of studies have been completed in vitro with neuron cultures and tissues, which may not accurately replicate the in vivo situation. Therefore, intravital manipulations are essential to achieve this goal. Here we introduce a technique that has been widely used in our lab to study the cargo trafficking in zebrafish at single-cell resolution. We use mitochondria as a representative neuronal cargo and provide step-by-step instructions on how to label specific cargoes within zebrafish Mauthner cells. This method can also be expanded to study the kinetics of other cargoes as well as the role of molecular regulators in axonal transport.