A Time Course Study Demonstrating m RNA, micro RNA, 18 S r RNA, and U 6 sn RNA Changes to Estimate PMI in Deceased Rat's Spleen

Abstract

Determining the postmortem interval (PMI) is important in criminal, civil, and forensic cases. We examined the feasibility of using the transcript abundances of m RNA s, 18 S r RNA, U 6 sn RNA, and micro RNA s as a means to estimate the PMI. We removed spleen tissues from rats at different PMI s under 4°C or 25°C and examined gene transcript abundances in these samples by RT‐q PCR. Using the algorithm geNorm, we found that micro RNA s to be appropriate control markers because they were less affected by PMI and temperature. We also characterized relationships between observed PMI and the transcript levels of the above‐mentioned RNA s. GAPDH 1 and ACTB 1 fluctuated slightly like cubic curves, while GAPDH 2 and ACTB 2 decreased rapidly. 18 S r RNA transcript level exhibited a parabolic‐like trend at 25°C and exponential growth at 4°C, while U 6 transcript level exhibited exponential decay at 25°C and a parabolic‐like trend at 4°C. Following validation, we conclude that GAPDH 2, ACTB 2, and 18 S r RNA are suitable makers in the accurate determination of PMI.