Nanometer-resolution fluorescence electron microscopy (nano-EM) in cultured cells

Area of Science:

• Cell Biology
• Microscopy
• Biophysics

Background:

• Precisely localizing proteins within cellular ultrastructure is crucial for understanding biological processes.
• Existing correlative microscopy techniques have limitations in resolution and fluorescence signal.

Purpose of the Study:

• To detail the methodology of nano-resolution fluorescence electron microscopy (nano-fEM).
• To present five key technical advancements improving the nano-fEM technique.

Main Methods:

• Correlative imaging combining super-resolution fluorescence microscopy and transmission electron microscopy.
• Sample preparation involving freeze-substitution with uranyl acetate for enhanced contrast and fluorescence retention.
• Utilizing organic fluorophores and ground-state depletion for improved fluorescence signal and temporal control.

Main Results:

• Achieved nano-resolution localization of individual proteins within electron micrographs.
• Demonstrated enhanced tissue contrast and reduced fluorescence loss using uranyl acetate.
• Showcased improved fluorescence brightness and temporal control with organic fluorophores and ground-state depletion.
• Broadened method utility using tissue culture cells and achieved sharper ultrastructure images with TEM.

Conclusions:

• Nano-fEM provides unprecedented spatial resolution for protein localization in cells.
• The presented technical advancements significantly enhance the performance and applicability of nano-fEM.
• This technique offers a powerful tool for dissecting molecular mechanisms at the nanoscale within their native cellular context.