A Study On The Relationship Between Nuclear DNA Degradation Of The Rat's Liver, Spleen Cells And The Postmortem Interval By Single Cell Gel Electrophoresis

Objective To detect the regulation of the liver, spleen cell nuclear DNA degradation after the rat's death by single cell gel electrophoresis(SCGE), in order to provide a new method for the estimation of early postmortem interval. At the same time, to compare the sensitivity between SCGE and Image Analyze Technique(IAT).Methods A rat death model was established by the carotid artery put the blood chronically. 1) For the liver and spleen, the samples were taken at 3-hour-interval within 30 hours and 27 hours respectively after the rat's death. After SCGE, the comet images were catched by the confocal microscope and analyzed by comet image analysis software(IMI1.0). 2) At the same time, the two kinds of tissues were taken at 0~63 hours and stained by Feulgen method. Then, to exam the DNA contains of above at different postmortem intervals by Image Analyze Technique(IAT) and do one-way ANOVA by SPSS 11.5 software.Results 1. An evident 'comet tail' was observed after electrophoresis for the liver and spleen cells. The 'tail length' and the 'tail moment' were significant different at 0~18h(liver cells) and 0~15h(spleen cells) respectively. They increased with an increased PMI, which was strong statistical correlated with PMI.2. By IAT, ID and IOD of the liver cell DNA were not significant different at 0~6 hours and AOD was not significant different at 0~9 hours; ID and AOD of the spleen cell DNA were not significant different at 0~6 hours and IOD was not significant different at 0~3 hours.Conclusion 1) Single cell gel electrophoresis might be used as a predictor of early postmortem interval; 2) SCGE was more sensitive than IAT for the estimation of very early time-points. 3) The comet image analysis software was a good tool for SCGE comet analysis.