We believe this may be the result of successive freeze-thaw cycles degrading the DNA, where fixing in a buffer protects the DNA from degradation.

Flash-freezing tissues is often regarded superior to other methods of cryogenically preserving tissues. We find that in archival settings, these tissues often show accelerated DNA degradation to tissues first fixed in a buffer such as ethanol before cryopreservation.

This research was really fun to work on and glad it's finally out there. Thanks to all coauthors whose effort made this work possible! @sabercatwoman.bsky.social @drsarahbray.bsky.social @zoojlinnsoc.bsky.social