Genomic DNA Stability Under Different Storage Conditions
DNA is a fragile biomolecule that can be degraded by various enzymatic and chemical processes. It is, therefore, essential to store DNA in a stable and safe environment to prevent degradation.
To this end, we tested the impact of different salts on the stability of genomic DNA at various storage conditions. Specifically, we examined the effect of calcium phosphate (CaP), calcium chloride (CaCl2) and magnesium chloride (MgCl2) on DNA stability under accelerated aging conditions.
Ethanol
Ethanol is a hygroscopic, colorless liquid with a relatively low freezing point (-114 deg C) and low toxicity and is used for many applications. Its hydroxyl group is polar and can participate in hydrogen bonding, making it a suitable solvent for DNA and RNA.
However, it is also susceptible to degradation under physical storage conditions. Using pure ethanol to store samples at room temperature can lead to increased rates of DNA degradation over time, potentially rendering the piece unusable for applications such as genome-wide sequencing.
Many factors affect the stability of genomic DNA, including its chemistry and physical environment. The storage of DNA at 4 degrees Celsius is one use for a chilled incubator that is both practical and abstract. Several approaches have been tested to enhance its strength. They involve encapsulation in an inorganic matrix or the adsorption of DNA onto biopolymeric matrices such as the commercial product DNA Stable20,21,23.
Temperature
As DNA is heated, it denatures and dissociates into single strands (melting). Many factors affect this process.
One such factor is cations that can lessen the repulsion between the phosphate groups.
This results in a lower melting temperature, making the molecule more stable. A refrigerator incubator is a crucial piece of equipment that offers a temperature-controlled environment for the storage of DNA.
In addition to cations, other factors that influence the melting temperature of DNA include pH and temperature.
For example, acidic conditions increase the hydrolysis rate of DNA by a factor of 2.
Additionally, water accelerates DNA degradation.
Because of the importance of DNA as a data storage medium, DNA must always remain stable. Therefore, DNA stability must be systematically explored and monitored in solution and dried samples under various storage conditions.
Rehydration
The stability of DNA is a critical issue for genomics research and the production of genetically engineered products and clinical drugs. Several factors affect the melting temperature (Tm) of DNA, including its backbone structure and ions present in buffers or storage matrices.
Many studies have investigated the effects of salts on the stability of DNA. This is because ions stabilize DNA in a solution by dissolving or displacing water molecules.
However, these salts can also cause ionization of the DNA phosphate backbone, which would lead to dehydration.
This can have detrimental effects on the DNA as it could cause structural degradation, such as depurination, which results in a lack of nucleotides when rehydrated or sequenced.
Moreover, salts can also cause cross-linking between the DNA strands, inhibiting the rehydration and amplification of DNA. Therefore, salts are essential when designing and selecting a storage system.
Freeze-thaw
The ability to accurately measure DNA stability over long timescales is an important goal. While this seems simple, it is not trivial, and many factors impact the resulting results, including environmental, temperature, buffer and temporal conditions.
One method of assessing the stability of genomic DNA at various storage conditions is freeze-thaw. This technique is a common way to preserve samples for long periods and can be used to store DNA as an aqueous solution or dry solid.
However, whether this approach will result in stable DNA over the long term because of degradation by enzymatic or chemical processes is still being determined. Also, freeze-thaw cycles can negatively impact the integrity of DNA samples if there is significant degradation during each cycle.
We analyzed 200 samples stored in different solutions over multiple intervals to better understand how the other preservation solutions affect DNA stability. The resulting data was analyzed using a multi-factor ANOVA (Table 1).
