Expansion microscopy of C. elegans

Area of Science:

• Cell Biology
• Microscopy Techniques
• Developmental Biology

Background:

• Expansion microscopy (ExM) provides nanoscale imaging by isotropically expanding hydrogel-embedded tissues.
• The C. elegans cuticle presents a barrier to antibody penetration, challenging ExM application.
• High-resolution imaging is crucial for understanding cellular structures and molecular localization in model organisms.

Purpose of the Study:

• To develop a robust expansion microscopy method for intact C. elegans.
• To enable simultaneous high-resolution imaging of multiple cellular components including proteins, RNA, and DNA.
• To create adaptable ExCel protocols for various imaging needs, including epitope preservation and ultra-high expansion.

Main Methods:

• Chemical fixation and hydrogel embedding of intact C. elegans.
• Isotropic expansion of processed specimens to achieve nanoscale resolution.
• Development of epitope-preserving and iterative ExCel protocols for advanced imaging.

Main Results:

• ExCel achieves ~65-75 nm resolution with 3.3-3.8x linear expansion in intact C. elegans.
• Simultaneous imaging of fluorescent proteins, RNA, and DNA locations was demonstrated.
• Epitope-preserving ExCel enabled antibody staining of endogenous proteins, and iterative ExCel allowed imaging after 20x expansion.

Conclusions:

• ExCel is a versatile toolkit for high-resolution imaging in C. elegans.
• The method facilitates detailed mapping of synaptic proteins and identification of novel proteins at cell junctions.
• ExCel is valuable for gene expression analysis in individual neurons within the same animal.