Assessment of decomposition on the integrity and stability of post-mortem mRNA

Abstract

Abstract Objective: Molecular information derived from RNA species has the potential to contribute to tissue specific identification, body fluid identification and post-mortem interval estimation. However, the reliability and validity of post-mortem RNA for the purpose of forensic identification is questionable. To determine the stability and purity of post-mortem RNA, sternal bone tissue was excised from Gallus gallus and Cercopithecus pygerythrus remains at five stages of decomposition (Fresh, Bloat, Active Decay, Advanced Decay and Dry Bone). Two RNA preservation methods, namely the commercially available RNAlater and the traditional -80 °C were evaluated and RNA purity and integrity were measured by UV absorbance and quality by RT-qPCR.Results: Animal models provide insights into the rapid degradation of RNA within an experimental setup of stages of degradation. Following the bloated stage (stage 2) of decomposition, RNA fragments and RT-qPCR amplification decreases. A positive correlation (p value 0.001) existed between the probability of DNA and/protein contamination and increased post-mortem interval. The results recommend against the sampling of RNA from advanced decomposed remains or remains where no circumstance of death and/or history is recorded. This study served as a proxy for development of methods later applied to unidentified human remains admitted to the South African Forensic Pathology Services at various stages of decomposition with no accompanied history or circumstance of death.