The Forensic Examination Of The Diatom In Dianchi Lake

[Objective]:This study was designed six locations diatom species of the genus differences research field in Dianchi Lake, the use of a scanning electron microscope to find out from the dominant populations in morphologically rich diatom population data field in Dianchi Lake, Dianchi Lake revealed diatom community domain characteristics for Analyzing drowned corpse overboard location lay the foundation for animal experiments in the scanning electron microscope positive results, the use of 18S rDNA sequencing, molecular biology detected diatoms, increase agility, improve the detection positive rate of detection range is expanded shorten detection time, reduce the difficulty of detection, providing more evidence for the diagnosis of drowning in water bodies. [Method]:in Dianchi Lake region selected six water sampling points, respectively, in summer and winter each sampling 500ml. First with microwave digestion samples were detected by the Dianchi Lake, rabbits and actual seizure cases; after then Chelex-100 method, CTAB method and, Power Soil DNA Isolation Kit extraction water diatom DNA, using PCR amplified 18S rDNA gene fragments, and by agarose gel electrophoresis, sequencing and BLAST 3130 amplified products were detected and analyzed. Experimental Methods and amplification system to be stabilized, take 18 rabbits animal experiments, including two as a negative control, more than 16 were thrown into the water sampling point it drowned. Experimental animals were taken heart, liver, spleen, lung and kidney were diatom test. [Results]:The Power Soil DNA Isolation Kit DNA extraction diatom better than traditional Chelex-100 method, CTAB method and microwave digestion; scanning electron microscopy Dianchi advantages derived species of algae crown plate, straight algae, Nitzschia, Cyclotella. Drowning rabbit lung tissue derived from animal experiments in the field of water containing samples of most species of diatoms, such as linear algae, Cyclotella, Navicula, Nitzschia, etc., can also be detected in liver and spleen. Drowned corpse case detection of lung tissue obtained water samples containing live most of diatom species, such as linear algae, Cyclotella, Navicula, Nitzschia, etc; liver, kidney, spleen tissue seen in diatom species a small ring algae, algae crown plate, Cymbella like. Unit case of diatom species and water samples and animal experiments remained the same. Water samples are consistent with 18SrDNA sequencing and scanning electron microscopy results; drowned rabbits visceral tissues were detected diatoms 18S rDNA amplification products, consistent with the SEM results; the most number of cases detected in the lungs, the best results; followed by kidney, spleen, liver and heart, and the detection rate compared with microwave digestion-the higher the rate of scanning electron microscopy, after the death of the dead bodies into the water group had no amplification product. In seven cases the subject case only one case of lung and liver in one case detected diatoms, and the rest were negative. [Conclusion]:Dianchi Lake diatom algae domain crested plate, straight algae, Nitzschia and Cyclotella and microwave digestion-scanning electron microscopy combined with better detection rate, it can be used for reasons of death of the bodies of water diagnostic methods; the results 18S rDNA methods for animal testing is desirable, if the optimizer diatom DNA template, design better diatom-specific primers, amplification efficiency can be maximized to achieve accurate identification of species, so that the identification of drowning inference and drowning place more accurate and credible.