Using Expansion Microscopy to Physically Enlarge Whole-Mount Drosophila Embryos for Super-Resolution Imaging

Area of Science:

• Developmental Biology
• Cell Biology
• Microscopy

Background:

• Confocal microscopy is crucial for 3D molecular localization but limited to ~200 nm resolution.
• Subcellular biology demands resolutions of tens of nanometers, exceeding traditional confocal capabilities.
• Hardware-based super-resolution microscopy offers higher resolution but requires specialized, inaccessible equipment.

Purpose of the Study:

• To present a protocol for Expansion Microscopy (ExM) in whole-mount Drosophila embryos.
• To enable visualization of subcellular details not resolvable by conventional confocal microscopy.
• To demonstrate ExM's utility for studying molecular localization and cellular architecture.

Main Methods:

• Expansion Microscopy (ExM) protocol for whole-mount Drosophila embryos.
• Utilized standard confocal microscopy for imaging expanded samples.
• Employed antibodies against Par-3, myosin II, and fluorescently labeled streptavidin for labeling.

Main Results:

• Achieved an approximate four-fold isotropic increase in sample size.
• Resolved distinct pools of myosin-GFP between adjacent cell cortices.
• Visualized fine details of the mitochondrial network architecture.

Conclusions:

• ExM provides an accessible method to enhance resolution with conventional confocal microscopes.
• The protocol is compatible with common immunofluorescence techniques and reagents.
• ExM significantly improves the ability to detect subcellular details in Drosophila embryos.