Patterns of Degradation in Prm1 and Semg1 Transcripts in Semen During 6 Months of Aging

Abstract

The purpose of this study was to study the degradation rates of mRNA molecules in semen stains as a possible approach to estimating the age of semen samples found at crime scenes. Specific primers directing amplicons of different lengths from transcripts from the sperm specific PRM1 gene and the seminal fluid specific SEMG1 gene were designed and synthesized. Using two fluid-specific primers allowed for the investigation of the difference in degradation rates between sperm and seminal fluid. No previous study had a large enough sample size to investigate if there is a difference in degradation rate among individuals. In this study, ten young adult males provided semen samples which were dried in 50�l aliquots and stored under controlled conditions. Aliquots were extracted using TRizol every 2 weeks for 6 months to obtain RNA for analysis. The degradation of 18S rRNA and GAPDH transcripts was analyzed as possible stable control transcripts along with PRM1 and SEMG1. 18S started showing increased degradation at 14 weeks while GAPDH seemed to having an increase in degradation over 6 months of aging. Degradation in control genes prevented meaningful statistical analysis from being completed. Looking at raw CT values there was great variation of mRNA concentration between individuals and time-points, but overall PRM1 and SEMG1 showed little to no indication of degradation from 0 to 6 months of aging. It is possible PRM1 and SEMG1 could still be useful in determining the age of semen samples if the samples were over 6 month of age. Additional research with a longer time course needs to be conducted to determine at what time PRM1 and SEMG1 start degrading quickly enough to be used to determine that age of semen samples.