Preservation of DNA

The preservation of DNA is of wide interest to scientists in disparate fields from biorepository management to pharmaceutical sciences. Although the term "preservation" is used by all these fields and refers to the maintenance of chemical and physical integrity of the DNA molecule, it should not be surprising that the perspectives of scientists from these distinct fields differ significantly. Most notably, the time frame for stability of a pharmaceutical product is approximately 2 years, whereas meaningful stability for an evolutionary biologist is measured in the hundreds of millions of years. Such divergent viewpoints not only have a significant effect on the time span of preservation, but also on what criteria are used to assess "stability." This review discusses the literature addressing the maintenance of DNA integrity from the perspective of developing methods that offer improved preservation. Specifically, studies on the stability of DNA in solution, frozen, and dried are discussed. The findings from these studies are compared, and the costs associated with maintaining DNA samples via contemporary methods (i.e., cold storage) are estimated. In light of the significant cost of maintaining samples in the frozen state, we conclude that dry storage at ambient temperatures would be adequate for many applications, and we suggest preservation strategies that should be investigated based on findings in the literature. In addition, we offer suggestions regarding critical studies that could be performed to compare published results from different fields using vastly different criteria to assess "stability.".