Correlation between RNA Degradation Patterns of Rat's Brain and Early PMI at Different Temperatures
Author(s): LV Yehui, LI Zhihong, TUO Zuo, LIU Li, li , BIAN Jie, MA Jianlong, CHEN Long
Pages: 165-170
Year: 2016 Issue: 3
Journal: Journal of Forensic Medicine
Keyword: forensic pathology; postmortem intervals; temperature; degradation; rats;
Abstract: Objective To explore the correlation between early postmortem interval(PMI)and eight RNA markers of rat's brain at different temperatures.Methods Total 222 SD rats were randomly divided into control group(PMI=0 h)and four experimental groups. And the rats in the experimental groups were sacrificed by cervical dislocation and respectively kept at 5 ℃, 15 ℃, 25 ℃and 35 ℃in a controlled environment chamber. The RNA was extracted from brain tissues, which was taken at 9 time points from 1 h to 24 h postmortem. The expression levels of eight markers,β-actin, GAPDH, RPS29, 18S rRNA, 5S rRNA, U6 snRNA, miRNA-9 and miRNA-125b, were detected using real-time fluorescent quantitative PCR, respectively. Proper internal reference was selected by geNorm software. Regression analysis of normalized RNA markers was performed by SPSS software. Mathematical model for PMI es-timation was established using R software. Another 6 SD rats with known PMI were used to verify the mathematical model.Results 5S rRNA, miR-9 and miR-125b were suitable as internal reference mark-ers for their stable expression. Bothβ-actin and GAPDH had well time-dependent degradation patterns and degraded continually with prolongation of PMI in 24 h postmortem. The mathematical model of the variation ofΔCt values with PMI and temperature was set up by R software and the model could be used for PMI estimation. The average error rates of model validation usingβ-actin and GAPDH were 14.1% and 22.2%, respectively.Conclusion The expression levels ofβ-actin and GAPDH are well cor-related with PMI and environmental temperature. The mathematical model established in present study can provide references for estimating early PMI under various temperature conditions.
Pages: 165-170
Year: 2016 Issue: 3
Journal: Journal of Forensic Medicine
Keyword: forensic pathology; postmortem intervals; temperature; degradation; rats;
Abstract: Objective To explore the correlation between early postmortem interval(PMI)and eight RNA markers of rat's brain at different temperatures.Methods Total 222 SD rats were randomly divided into control group(PMI=0 h)and four experimental groups. And the rats in the experimental groups were sacrificed by cervical dislocation and respectively kept at 5 ℃, 15 ℃, 25 ℃and 35 ℃in a controlled environment chamber. The RNA was extracted from brain tissues, which was taken at 9 time points from 1 h to 24 h postmortem. The expression levels of eight markers,β-actin, GAPDH, RPS29, 18S rRNA, 5S rRNA, U6 snRNA, miRNA-9 and miRNA-125b, were detected using real-time fluorescent quantitative PCR, respectively. Proper internal reference was selected by geNorm software. Regression analysis of normalized RNA markers was performed by SPSS software. Mathematical model for PMI es-timation was established using R software. Another 6 SD rats with known PMI were used to verify the mathematical model.Results 5S rRNA, miR-9 and miR-125b were suitable as internal reference mark-ers for their stable expression. Bothβ-actin and GAPDH had well time-dependent degradation patterns and degraded continually with prolongation of PMI in 24 h postmortem. The mathematical model of the variation ofΔCt values with PMI and temperature was set up by R software and the model could be used for PMI estimation. The average error rates of model validation usingβ-actin and GAPDH were 14.1% and 22.2%, respectively.Conclusion The expression levels ofβ-actin and GAPDH are well cor-related with PMI and environmental temperature. The mathematical model established in present study can provide references for estimating early PMI under various temperature conditions.
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