ABSTRACT
Objective To develop a PCR-based method of detecting plankton 16S rDNA for the i dentification of death by drowning. Methods Fifteen Sprague-Dawley rats were divided randomly into three groups: the death by drowning group, the group of submerging after death and the control group. After sacrificing by different ways, the brain, liver, kidney and lung of rats were taken out respectively and DNA were extracted from the tissues of these organs and were amplified subsequently by specific primers selected from the third and fourth variable regions of plankton 16S rDNA. Results The specific amplification products were detected from all 5 samples of lung tissue ( 100% ) , 4 samples from liver and kidney tissues (80% ) , and 3 samples from brain tissue (75% ) in the group of death by drowning. No amplification product was detected in all samples of the control group and the amplification product was detected only in 1 sample of lung (20% ) in the group of submerging after death. Conclusion The PCR-based method of detecting plankton 16S rDNA for the identification of death by drowning is certainly feasible.
ABSTRACT
Objective To evaluate the value of detecting chlorophyll related genes of plankton in the diagnosis of drowning. MethodsEighteen rabbits were divided randomly into three groups: death by drowning (n=10), postmortem submersion (n=6) and control (n=2). The heart blood, lung, liver, kidney and brain tissues were taken from every rabbit. After isolated plankton from tissues with percoll and extracted their DNA, the chlorophyll-related genes, including EG (EG1 and EG2) and SK (SK1 and SK2), were detected using PCR technique. Meanwhile, diatom test was also performed from lung and liver tissues by nitric acid digestion method. ResultsFor the drowning group, the specific amplification products for EG1 were detected from 9 samples in heart blood, 10 samples in lung, 9 samples in liver, 7 samples in kidney and 8 samples in brain. The products for EG2 were detected from 8 samples, 10 samples, 7 samples, 5 samples and 7 samples accordingly. There were a small number of positives in heart blood, lung and kidney with SK1 and SK2 (≤2). For the postmortem submersion group, only one case was positive from heart blood and lung tissue respectively for EG1. No amplified product was detected for EG1 and EG2 in various tissues in control group, and also no product was detected for SK1and SK2 in other groups. In addition, diatoms were detected from 9 lung and 3 liver tissues in drowning group with the nitric acid digestion, and only one sample of lung was positive in the postmortem submersion group. ConclusionThe detection rate of the chlorophyll-related gene EG with PCR method was higher than that of diatom with nitric acid digestion method in drowning victims, and it can be used as a potentially useful tool for diagnosing drowning.
ABSTRACT
Drowning represents one of the leading causes of unnatural death. The plankton test is still considered as one of the useful methods for medico-legal investigation of death by drowning although controversies concerning the reliability of the test exist. The methods commonly used for detection of planktons generally include microscopic examination after tissue samples are destructed with or without strong acid, and detection of the planktons by molecular biological techniques. The evaluation of the positive results by the former methods are limited by the physical-chemical characters of the planktons. Detection of DNA genetic markers by molecular biological techniques, which can provide abundant information and is applicable to studying various planktons, is a novel method helpful for investigation of drowning. In the present paper, several techniques for detection of planktons were reviewed as references for medico-legal practitioners in investigation of suspected cases of drowning.