死亡大鼠看家基因mRNA时序性降解的组织差异性研究

目的研究死亡大鼠看家基因mRNA时序性降解的组织差异性，评价其用于死亡时间推断的价值。方法SD大鼠20只分为死后0、1、3、5、7d共5组，脊椎脱臼法处死大鼠，提取大鼠心、肝、脾、肺、肾、脑组织，在相应时间段提取RNA，应用一步法RT-PCR技术检测各组织中看家基因GAPDHmRNA和β-actinmRNA的水平，Vilber凝胶图像分析系统测定扩增产物IOD值，SPSS10．0统计软件对数据进行方差分析。结果GAPDHmRNA、β—actinmRNA扩增产物相对灰度与积分光密度值随死后经过时间的延长而逐渐减小，且与死亡时间显著相关，大鼠脾脏和脑组织GAPDHmRNA和β-actinmRNA在死后5d内可检出，心脏和肾脏在死后3d内可检出，而肝脏和肺脏GAPDHmRNA和β-actin mRNA降解较快，仅在死后1d内可检出。结论脑组织和脾脏中mRNA稳定性较好，适用于PMI特别是晚期PMI的推断。除环境温度外，环境湿度也是死亡时间推断中的重要影响因素。

Tissue variability of housekeeping mRNA degradation in dead rats

Objective To study the tissue variability of housekeeping mRNA degradation in dead rats in order to seek suitable tissues for PMI.Methods Total RNA was extracted,at given postmortem intervals (0d,1d,3d,5d,7d),from heart,liver,spleen,lung,kidney,brain of rats;the level of GAPDH mRNA andβ-actin mRNA were measured by one-step RT-PCR. PCR products were assessed by electrophoresis in agarose gels.Results The results showed that IOD and RG of PCR products in GAPDH mRNA andβ-actin mRNA decreased over time with the significant correlation of postmortem intervals.The bands of two housekeeping genes could be detected up to 5 days postmortem of spleen and brain,up to 3 days postmortem of heart and kidney,and 1 day postmortem of liver and lung by densitometric analysis of the gel images.Conclusion mRNA of dead body is most stable in the brain and spleen,which chould used to estimate the PMI,especially for the late PMI estimation.Ambient temperature and humidity should be considered as the important factors for estimation of time since death.