Forensic RNA analysis for estimating the age of body fluid stains

Strathclyde theses - ask staff. Thesis no. : T15425The first appearance of ribonucleic acid (RNA) in forensic science research was in 1984 in the study of post-mortem tissues. Since then, many studies have explored the role of gene expression and its potential applications in forensic science. Some RNA types such as messenger RNA (mRNA) and microRNA (miRNA) have been subject to increasing interest in the forensic science community.It has been shown that analysis of RNA molecules can also be applied to determine the time when a biological stain was deposited at a crime scene, by analysing their stability and degradation rate. Estimating the age of a biological stain can provide essential information to an investigation. This research has analysed the expression and degradation level of different types of body fluidspecific RNA markers, including mRNA and miRNA markers, with the aim of identifying RNA markers that can be used to estimate the age of three types of body fluid (blood, saliva and semen). In this approach, reverse transcription quantitative PCR (RT-qPCR) has been utilised using appropriate primers and TaqMan® probes.;The relative expression ratio (RER) between different types of body fluid-specific RNA markers was then examined in aged body fluid samples across one-year storage interval, with the aim of developing a method to estimate the age of body fluid stains recovered at crime scenes.Each RNA marker exhibited unique degradation behaviour across ageing time points for blood, saliva and semen samples, with miRNAs showing high stability. Statistically significant correlations were found between the RERs of RNA markers and ageing time points, exhibiting a non-linear relationship.Overall, the RERs of body fluid-specific markers can be considered as apotential method for estimating the age of biological stains, and this has a widerange of applications in forensic science.The first appearance of ribonucleic acid (RNA) in forensic science research was in 1984 in the study of post-mortem tissues. Since then, many studies have explored the role of gene expression and its potential applications in forensic science. Some RNA types such as messenger RNA (mRNA) and microRNA (miRNA) have been subject to increasing interest in the forensic science community.It has been shown that analysis of RNA molecules can also be applied to determine the time when a biological stain was deposited at a crime scene, by analysing their stability and degradation rate. Estimating the age of a biological stain can provide essential information to an investigation. This research has analysed the expression and degradation level of different types of body fluidspecific RNA markers, including mRNA and miRNA markers, with the aim of identifying RNA markers that can be used to estimate the age of three types of body fluid (blood, saliva and semen). In this approach, reverse transcription quantitative PCR (RT-qPCR) has been utilised using appropriate primers and TaqMan® probes.;The relative expression ratio (RER) between different types of body fluid-specific RNA markers was then examined in aged body fluid samples across one-year storage interval, with the aim of developing a method to estimate the age of body fluid stains recovered at crime scenes.Each RNA marker exhibited unique degradation behaviour across ageing time points for blood, saliva and semen samples, with miRNAs showing high stability. Statistically significant correlations were found between the RERs of RNA markers and ageing time points, exhibiting a non-linear relationship.Overall, the RERs of body fluid-specific markers can be considered as apotential method for estimating the age of biological stains, and this has a widerange of applications in forensic science