Adverse Effect of Air Exposure on the Stability of DNA Stored at Room Temperature
However, DNA, even thoroughly dried, if left exposed to air regains a fair amount of water and still undergoes strand breaking and oxidation. Moreover, the presence of the atmospheric pollutant, ozone, very reactive toward DNA, should not be neglected. Thus, it appears that long-term storage of DNA at room temperature may require an absolute protection from the atmosphere. However this protection cannot be provided by plastic containers since they are known to be permeable to moisture vapour.
RESULTS: We therefore developed a new procedure for room temperature storage of DNA whereby DNA samples are stored under an anoxic and anhydrous atmosphere in small glass vials fitted in stainless-steel, laser-sealed capsules. Under these conditions, at room temperature or 70 °C, no DNA degradation was detected after 8 month or 1 week storage, while samples kept in air, in closed plastic tubes, either naked or in the presence of matrixes, underwent clear (or strong) degradation and/or aggregation.
CONCLUSION: This study demonstrates the necessity of protecting DNA from air in order to preserve its integrity for room temperature storage.
Marthe Colotte, Delphine Coudy, Sophie Tuffet, Jacques Bonnet.
Biopreservation and Biobanking April 2011, Vol. 9, No. 1: 47-50.
http://www.liebertonline.com/doi/abs/10.1089/bio.2010.0028
04/2011 | Publication parue dans Biopreservation and Biobanking journal
Optimization of DNA extraction from brown algae (Phaeophyceae) based on a commercial kit
Large-scale DNA molecular studies require reliable and efficient tools for DNA extractions. However, for some plant species and brown algae, isolation of high-quality DNA is difficult. We developed a novel method for isolating high-quality DNA from the polysaccharide-rich and polyphenol-rich brown algae based on a commercial kit and protocol (Qiagen) by optimizing the lysis step and including a chloroform/isoamyl alcohol supplementary purification step. DNAs from 24 brown algal species extracted using the original and the modified Qiagen protocol were compared for yield, quality, and effectiveness in PCR amplification. There was no significant difference in the yields between protocols. However, a statistically significant increase in DNA purity was obtained with the modified protocol, for which the A260/A280 and A260/A230 absorbance ratios averaged 1.66 ± 0.05 and 1.31 ± 0.01, respectively, compared to 1.37 ± 0.04 and 0.52 ± 0.04 with the original protocol. DNAs extracted by the modified procedure were more successfully amplified by PCR (nuclear, mitochondrial, and chloroplastic regions) than DNAs extracted using the original commercial kit and protocol. Importantly, the modified protocol can be applied in a high-throughput (e.g., 96-well plate) format, allowing a higher efficiency for downstream molecular analysis. In addition, improved DNA quality could increase its stability for long-term storage.
Alodie Snirc, Thomas Silberfeld, Jacques Bonnet, Annie Tillier, Sophie Tuffet, Jian-Sheng Sun
Volume 46, Issue 3, pages 616–621
http://onlinelibrary.wiley.com/doi/10.1111/j.1529-8817.2010.00817.x/abstract
June 2010 | Publication parue dans Journal of Phycology
Chain and conformation stability of solid-state DNA: implications for room temperature storage
There is currently wide interest in room temperature storage of dehydrated DNA. However, there is insufficient knowledge about its chemical and structural stability. Here, we show that solid-state DNA degradation is greatly affected by atmospheric water and oxygen at room temperature. In these conditions DNA can even be lost by aggregation. These are major concerns since laboratory plastic ware is not airtight. Chain-breaking rates measured between 70°C and 140°C seemed to follow Arrhenius’ law. Extrapolation to 25°C gave a degradation rate of about 1-40 cuts/105 nucleotides/century. However, these figures are to be taken as very tentative since they depend on the validity of the extrapolation and the positive or negative effect of contaminants, buffers or additives. Regarding the secondary structure, denaturation experiments showed that DNA secondary structure could be preserved or fully restored upon rehydration, except possibly for small fragments. Indeed, below about 500 bp, DNA fragments underwent a very slow evolution (almost suppressed in the presence of trehalose) which could end in an irreversible denaturation. Thus, this work validates using room temperature for storage of DNA if completely protected from water and oxygen.
Thèse de doctorat sur la stabilité de l’ADN à l’état sec
Colotte M. Stabilité chimique et conformationnelle de l'ADN à l'état sec et à température ambiante Thèse N°1535 Université de Bordeaux 2, 2008, présidée par M. Jean Weissenbach, directeur du Génoscope.
Présentée et soutenue à huis clos.
21 juillet 2008 | Voir l'article
Simultaneous assessment of average fragment size and amount in minute samples of degraded DNA
Analytical Biochemistry
Marthe Colotte, Vincent Couallier, Sophie Tuffet, Jacques Bonnet (2009), doi:10.1016/j.ab.2009.02.003
