Author ORCID Identifier
https://orcid.org/0000-0002-1199-5264
Defense Date
2015
Document Type
Directed Research Project
Department
Forensic Science
First Advisor
Sarah Seashols-Williams
Second Advisor
Zendra Zehner
Third Advisor
James Robertson
Abstract
In an attempt to determine the boundaries of degradation in nucleic acids with increased sensitivity, and provide support for a molecular method for body fluid identification, this study used specific treatments that are commonly found in crime scenes or are present in our daily environment to degrade DNA, messenger RNA, and microRNA in bodily fluids. Recently, the forensic science field has explored the use of RNAs regarding a molecular-based method for forensic body fluid identification. Specifically, messenger RNAs and microRNAs have been researched as markers for body fluids. Messenger RNAs are multifunctional and are shorter than DNA and some are differentially expressed, they are found throughout the entire human body. MicroRNAs are small structures that suppress protein expression by binding to messenger RNA in the cytosol. Thus, microRNAs also have the potential to be tissue-specific. As such, miRNAs are simpler and potentially less problematic than DNA and mRNAs regarding detection. Blood, urine, semen, and saliva were collected and dried. The samples were then exposed to bleach, ultraviolet light and detergent treatments, in addition to two different elevated temperatures, acidic and basic environments. Using a controlled environmental chamber, untreated samples of saliva, semen, urine and blood were placed under specified parameters that were equivalent to a Virginia summer day. The instrument controlled the irradiance, air temperature, and humidity levels for up to 14 consecutive days. DNA and RNA were isolated and quantitative Polymerase Chain Reaction (qPCR) was used to evaluate full length and mini amplicons of the STR gene TPOX. The mRNA and miRNA stains were extracted in the same manner and reverse transcription-qPCR (RT-qPCR) was performed using GAPDH, β-actin, and/or Let-7g. Each sample was analyzed and compared against the untreated controls for their relative abundance. For the majority of the treated samples, the miRNAs under evaluation were detectable and comparable to the untreated controls. Semen and saliva under the bleach treatment showed major degradation, as indicated by the amplification failure; however, blood samples were remarkably stable, given that there were no failed amplification reactions observed throughout all the treatments. MicroRNAs express a declining pattern between the 2 to 8-hour timeframe; however, their abundance levels begin to increase after the 10-hour mark. The DNA and mRNA samples declined in abundance after being subjected to various treatments, but were detectable. In conclusion, this study exhibits how harsh environmental effects can play a detrimental role on biological evidence and provides an inference about the best biological material for body fluid identification based upon degradative characteristics.
Accessibility Note
Content is digitally accessible 2026
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
10-21-2026