Molecular studies of time- and environment-dependent effects on bone DNA survival

In the past few years, many studies of human identification through DNA analysis of skeletal material have been published; however, the potential use of DNA technology to determine the postmortem interval (PMI) is still under investigation. Compared with soft tissue, skeletal materials provide longer protection against DNA degradation. We examined the effects of PMI and environmental conditions, i.e. temperature and humidity on bone DNA survival by examining human rib bone samples. Samples were taken within 24 hours postmortem and then stored from 103 to 445 days in four different conditions, namely freezing, ambient conditions, high humidity and underground burial. Bone DNA extracts were assessed by gel electrophoresis. The authenticity of the DNA could be verified by Alu sequence Southern blot hybridization. The results confirmed the strong effects of environment on DNA stability. Burial and high humidity conditions resulted in almost complete degradation of DNA in our samples. However, there was no correlation detected between the amount of DNA or the pattern of DNA fragmentation and PMI in our studies.