As biobanking technology continues to advance, biobankers are facing more and more opportunities to collect, store and/or analyze specimens from a wide range of environments. Naturally, the optimal setting for dealing with these samples is a sterile lab stocked with the proper equipment, reagents and plenty of cold storage.
But that optimum doesn’t exist in a field setting.
Biosamples from the field –from places like archaeological excavations, crimes scenes or disaster sites –can provide a wealth of information; however, they need special care to produce meaningful insights. Researchers who work in these environments need to clear numerous hurdles, including sample degradation, decomposition of nucleic acids and contamination with foreign DNA (to name just a few).
Are you facing these types of challenges? If so, check out this review published in Biopreservation and Biobanking earlier this year. The authors discuss how harsh environments can affect the quality of a biosample and the best methods for collection and storage of samples from these settings.
Here are my three key take-aways:
Decomposition begins immediately after death.
DNA is a complex and fragile molecule, and it starts to degrade immediately after a cell dies. During DNA degradation, large chromosomes break down into smaller fragments. This process can be accelerated if a sample is exposed to sunlight, water or fire, making DNA recovery all the more problematic. Fragmented DNA can make amplification and sequencing difficult or even impossible. Cold storage is ideal, but drying and liquid preservatives can be used.
Cryopreservation essentially “freezes” the processes that degrade cellular material and is the best option for storing biosamples. However, in certain cases (like during natural disasters), access to cryopreservation equipment –or even electricity –could be limited. In these situations, alternative approaches (drying, use of liquid preservatives, etc.) can help reduce any further changes to the samples.
Drying removes water from a sample, and so decreases microbial and enzymatic activity. It can be achieved by using heat, silica gel or commercial options, such as FTA cards, which are common for forensic sample collection. Liquid preservatives can kill bacteria and reduce further degradation of nucleic acids and biomarkers. Alcohol, DMSO (dimethyl sulfoxide) and commercial solutions are available for liquid preservation.
Despite the difficulties and unpredictability, harsh environments can yield valuable information.
Although there are challenges to overcome, analysis of DNA collected in the field can be successfully accomplished when the proper steps are taken for maximum samples integrity. For example, many victims of the World Trade Center attacks were identified solely through DNA analysis. In addition, DNA from archaeological investigations has revealed that humans and Neanderthals likely mated extensively during the human migration out of Africa. And finally, DNA evidence has helped identify criminals at numerous crime scenes, even when only a small amount of material is present – a single hair or drop of blood, for example.
For more information, see the full article, Collecting and preserving biological samples from challenging environments for DNA analysis, available here.