Cryo-SOFI enabling low-dose super-resolution correlative light and electron cryo-microscopy

Area of Science:

• Biophysics
• Microscopy
• Cell Biology

Background:

• Correlative light and electron cryo-microscopy (cryo-CLEM) integrates fluorescence cryo-microscopy (cryo-FM) and cryo-electron microscopy (cryo-EM) for high-resolution imaging.
• Existing super-resolution cryo-CLEM methods face limitations due to high laser intensity requirements, necessitating cryo-protectants that compromise cryo-EM image quality and sample compatibility.

Purpose of the Study:

• To introduce a novel low-dose super-resolution imaging technique compatible with cryo-EM.
• To overcome specimen devitrification issues in super-resolution cryo-CLEM.

Main Methods:

• Development of cryogenic super-resolution optical fluctuation imaging (cryo-SOFI), a low-dose super-resolution technique based on the SOFI principle.
• Application of cryo-SOFI to various biological samples without special preparation, ensuring compatibility with conventional cryo-EM specimens.

Main Results:

• Cryo-SOFI achieves resolutions up to approximately 135 nm, a threefold improvement over conventional cryo-FM.
• The method maintains the specimen in a vitrified state, crucial for subsequent cryo-EM analysis.
• Cryo-SOFI does not negatively impact cryo-EM image quality and avoids specimen devitrification.

Conclusions:

• Cryo-SOFI provides a general and accessible solution for super-resolution cryo-CLEM, enhancing resolution without compromising sample integrity.
• The technique is easily implementable in existing cryo-FM systems and does not require complex optical setups.