DNA persistance in soft tissues exposed to extreme environments

Abstract

After death DNA becomes progressively more fragmented as biological tissue degrades and this results in a decreasing ability to gain a complete STR profile. When extracting and profiling DNA from human remains understanding the likely persistence of DNA in different tissues is important. Studies in the UK have demonstrated that when using pigs as an experimental model, DNA up to 400 bp will persist for up to 3 weeks in the summer. However, it is well known that DNA degradation, especially in muscle tissue that has not become dehydrated, is dependent to a large degree on temperature. To assess DNA persistence in more extreme environmental conditions pig carcasses were exposed to the environment in Thailand during June for 10 days, with samples being collected every 12 h: muscle tissue was present for up to three days post-mortem. Extracted DNA could not be amplified after 36 h exposure unless the muscle was collected from tissue that was in contact with the ground; DNA persisted for up to 72 h in these samples.