Damage to biological samples caused by the electron beam during electron microscopy

Area of Science:

• Electron microscopy
• Radioautography
• Molecular biology

Background:

• Electron microscopy is a vital tool for visualizing biological structures.
• Beam damage can alter or destroy delicate biological specimens during imaging.
• Quantifying this damage is crucial for accurate interpretation of results.

Purpose of the Study:

• To develop and apply a novel method for directly measuring beam damage in biological specimens.
• To assess the extent of macromolecular damage under standard electron microscopy conditions.

Main Methods:

• Development of a radioautography-based technique to quantify specific radioactivity.
• Measurement of radioactivity in labeled biological samples (ribosomes, R17 virions) before and after electron beam exposure.
• Comparison of mass loss in exposed versus unexposed samples.

Main Results:

• A new method accurately measures beam damage in biological samples.
• Macromolecular samples like ribosomes and R17 virions experience severe damage.
• 15-40% mass loss observed in samples after just 30 seconds of beam exposure.

Conclusions:

• Standard electron microscopy procedures cause substantial damage to biological macromolecules.
• The developed radioautography method provides a reliable way to quantify beam-induced sample degradation.
• Findings highlight the need for optimized electron microscopy protocols to preserve sample integrity.