Protocol for BATTLE-1EX: A High-Resolution Imaging Method to Visualize Whole Synaptic Structures and their Components in the Nervous System

This protocol describes BATTLE-1EX, which is a combined method of BATTLE-1 and expansion microscopy to obtain high-resolution imaging of whole synaptic structures and their components of hippocampal neural circuits. BATTLE-1 uses two genetically engineered recombinase proteins and competition between two recombinases that can be independently titrated, resulting in a tunable proportion of mCherry+/YFP− and YFP+/mCherry− cells. As a combinational method, BATTLE-1EX has the potential to visualize and dissect whole synaptic structures in numerous regions in the brain. For complete details on the use and execution of this protocol, please refer to Kohara et al. (2020).