The Effects of Different Storage Conditions and Repeated Freeze/Thaw Cycles on the Concentration, Purity and Integrity of Genomic DNA

Safarikova, M.; Kubena, A. A.; Frankova, V.; Zima, T.; Kalousová, Marta

doi:10.14712/fb2021067010010

Folia Biologica > Archive > 2021, Vol. 67 > Issue 1 > The Effects of Different Storage…

Fol. Biol. 2021, 67, 10-15

https://doi.org/10.14712/fb2021067010010

The Effects of Different Storage Conditions and Repeated Freeze/Thaw Cycles on the Concentration, Purity and Integrity of Genomic DNA

M. Safarikova¹, A. A. Kubena¹, V. Frankova², T. Zima¹, Marta Kalousová¹

¹Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
²Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic

Received December 2020
Accepted May 2021

The crucial requirement of molecular genetic methods is high-quality input material. The key question is “how to preserve DNA during long-term storage.” Biobanks are recommended to aliquot isolated DNA into provided volumes. The aim of this study was to analyse the effect of repeated freezing and thawing on the genomic DNA integrity, quality and concentration. The aliquoted DNA isolated from blood cells using the automatic MagNA system and manual salting out method underwent freeze/thaw cycles at different storage conditions (−20 °C, −80 °C and liquid nitrogen). The average initial concentrations were 270.6 ng/μl (salting out method) and 125.0 ng/μl (MagNA). All concentration deviations relative to the concentration after the first freeze/ thaw cycle were less than 5 % for −20 °C and −80 °C cycling with both isolation methods. The average percentage differences of liquid nitrogen samples were higher, and the MagNA isolation method showed significant differences. There were no significant changes in the DNA purity or quality. The repeating freeze/ thaw up to 100 cycles (through −20 °C and −80 °C, respectively) did not significantly influence the integrity, concentration, or purity of genomic DNA, suggesting that storage of samples in high-volume pools without multiple aliquoting is possible. Storage in a freezer seems to be the most suitable way of long-term DNA preservation, because liquid nitrogen storage leads to formation of DNA clumps.

Keywords

gDNA, storage, freeze, thaw cycles, concentration, purity, integrity.

Funding

The study was supported by the European Regional Development Fund, projects BBMRI-CZ EF16_013/0001674 and A-C-G-T CZ.02.1.01/0.0/0.0/16_026/0008448; MEYS, RDI infrastructure, project No. LM2018125; MH CZ DRO VFN 64165 and Progres Q25.