ABSTRACT
OBJECTIVES@#To identify the drop-off location of victims in drowning cases, and confirm whether it is a fatal drowning or the victim is thrown into the water after death by detecting part of 5.8S sequence and second internal transcribed spacer （ITS2） （5.8S+ITS2） of diatom rDNA in water and organs.@*METHODS@#Two cases identified by diatom examination, which received by Nanjing Municipal Public Security Bureau Forensic Center, were taken as the research objects. The difference of the population structure of algae in water and human tissue was analysed by length polymorphism of 5.8S+ITS2 marker.@*RESULTS@#In case 1, similar species of diatom were detected from victim's lung and liver tissues and the water sample. Two kinds of DNA fragments with length of 330 bp and 376 bp were detected from victim's lung tissue and the water sample using 5.8S+ITS2 marker, which could confirm the victim was drowning before death. In case 2, there was no diatom found in victim's lung and liver tissues. Only one kind of DNA fragment with length of 331 bp and low relative fluorescence unit （RFU） was obtained from victim's lung tissue using 5.8S+ITS2 marker, thus the victim was thrown into the water after death.@*CONCLUSIONS@#The experimental results of the two cases in present study are consistent with the actual facts and the result of the diatom microscopic examination. The difference of population structure of specific microorganism in water and human tissue can be detected by 5.8S+ITS2 marker, which can help to identify the drop-off location of victims in drowning cases, and confirm whether it is a fatal drowning or the victim is thrown into the water after death.
Subject(s)
Humans , DNA, Ribosomal/analysis , Diatoms/genetics , Drowning/diagnosis , Liver , LungABSTRACT
Objective To solve the problems of low success rate in detecting complete DNA typing of biological samples,such as naturally fallen hair,severely degraded bones and teeth which is difficult in forensic identification.Methods We applyed a specific retrotransposon (RE) DNA sequences in identification,with DNA fragment length of 60-125 bp.A RE combined with 21 loci were used in individual discrimination to compute the likelihood (LR) values and combined paternity index (CPI)values in phylogenetic identification.Results This research obtained high success rate in detection of hair stem without follicles and severely degraded biological samples.We found that most of the LR values were 108-1012,which met the requirement of identity establishing.Through the CPI values,it was difficult to support the assumptions,with most of the CPI values less than 10 000.Conclusions The RE with 21 loci can be used for individual discrimination,but more loci are need for applying in phylogenetic identification.