The Effect of Mixing Seminal Fluid and Vaginal Secretion on the Expression of miRNA Markers in a Simulated Forensic Scientific Detection

Abstract

   Forensic investigators usually recover body fluids from crime scenes, and their identification is a necessary part of forensic case study. By establishing a connection between sample donors and actual criminal activities, determining the type and origin of body fluids found at a crime scene will provide crucial information for crime scene reconstruction. A quantitative Real-time PCR technique was used to calculate the expression levels of miR-10b and miR-135b, as well as miR-124-3p and miR-372, in semen, vaginal fluid stains, and their mixture. The identification and stability of the target genes were evaluated using SNORD-47 as a reference gene. The results of this study reported that the MiR-10b and miR-135b were expressed at higher levels in semen stains than in vaginal stains; miR-124-3p and miR-372 were expressed at higher levels in vaginal stains than in semen stains; and four miRNAs were expressed in semen/vaginal mix stains but at lower levels than in primary samples. Additionally, the results revealed that in comparison to the reference gene SNORD-47, the expression levels of miR-10b and miR-135b (semen) and miR-124-3p and miR-372 (vaginal secretion) were higher in this sample. For two weeks, a mixture of semen and vaginal stains has no effect on miRNA expression levels and has good stability.