Superresolution measurements in vivo: imaging Drosophila embryo by photoactivated localization microscopy

Visualization and quantification of supramolecular assemblies in cells are essential to understand the design principles of cells and tissues. The advent of photoactivated localization microscopy (PALM) and related techniques has offered unprecedented information on protein supramolecular assemblies in 3-D with a spatial resolution of a few tens of nanometers. Yet application of PALM microscopy for in vivo studies remains challenging. This chapter describes how to implement PALM microscopy for quantitative analysis of intercellular adhesion in the Drosophila embryo. Our protocol describes the sample preparation, the imaging setup, and the acquisition procedure. We also discuss how to proceed with quantitative analysis of data. Initially designed and implemented for Drosophila embryo imaging of intercellular adhesion, this protocol can be readily adapted to other structures than adhesions and other organisms such as Zebrafish or Caenorhabditis elegans.