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

Moser F., Pražák V., Mordhorst V., Andrade DM., Baker LA., Hagen C., Grünewald K., Kaufmann R.

Correlative light and electron cryo-microscopy (cryo-CLEM) combines information from the specific labeling of fluorescence cryo-microscopy (cryo-FM) with the high resolution in environmental context of electron cryo-microscopy (cryo-EM). Exploiting super-resolution methods for cryo-FM is advantageous, as it enables the identification of rare events within the environmental background of cryo-EM at a sensitivity and resolution beyond that of conventional methods. However, due to the need for relatively high laser intensities, current super-resolution cryo-CLEM methods require cryo-protectants or support films which can severely reduce image quality in cryo-EM and are not compatible with many samples, such as mammalian cells. Here, we introduce cryogenic super-resolution optical fluctuation imaging (cryo-SOFI), a low-dose super-resolution imaging scheme based on the SOFI principle. As cryo-SOFI does not require special sample preparation, it is fully compatible with conventional cryo-EM specimens, and importantly, it does not affect the quality of cryo-EM imaging. By applying cryo-SOFI to a variety of biological application examples, we demonstrate resolutions up to ∼135 nm, an improvement of up to three times compared with conventional cryo-FM, while maintaining the specimen in a vitrified state for subsequent cryo-EM. Cryo-SOFI presents a general solution to the problem of specimen devitrification in super-resolution cryo-CLEM. It does not require a complex optical setup and can easily be implemented in any existing cryo-FM system.

DOI

10.1073/pnas.1810690116

Type

Journal article

Journal

Proceedings of the National Academy of Sciences of the United States of America

Publication Date

03/2019

Volume

116

Pages

4804 - 4809

Addresses

Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, OX3 7BN Oxford, United Kingdom.

Keywords

Cell Line, Endoplasmic Reticulum, Mitochondria, Animals, Humans, Cryoelectron Microscopy, Microscopy, Fluorescence

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