Pathological diagnosis of drowning remains a challenge for forensic science, because of a lack of pathognomonic findings. We analyzed microbiota and surfactant protein in the lungs for a novel diagnosis of drowning. All rats were divided into drowning, postmortem submersion, and control groups. The water, lungs, closed organs (kidney and liver), and cardiac blood in rats were assayed by targeting 16S ribosomal RNA of Miseq sequencing. Lung samples were analyzed by immunohistochemical staining for surfactant protein A. The closed organs and cardiac blood of drowned group have a lot of aquatic microbes, which have not been detected in postmortem submersion group. Furthermore, intra-alveolar granular staining of surfactant protein A (SP-A) was severely observed in the drowned group than the postmortem submersion and control groups. The findings suggested that the presence of aquatic microbiota in the closed organs and increased expression of SP-A could be markers for a diagnosis of drowning.
Human have the microorganisms in the skin, gut and mouth. Human skin microbiome based on the 16S rRNA encoding gene can reveal bacterial species diversity. Also bacterial species in the skin have diverse and unique composition between individuals. We thought that a bacterial fingerprint obtained from surfaces including computer keyboards aids forensic individual identification in case of evidence deficiency. Next generation sequencing was used to analyze the bacterial community on objects and fingertips to match the object to the individual. The 16S rRNA gene sequence was submitted to EMBL SRA with accession number PRJEB8760. Higher similarity of bacterial community between public computer keyboards and laboratory member's fingertips were evident than between other locations including doorknobs. Here we studied the challenges that bacterial fingerprint can be used as a human identification tool in forensic fields.
Telogen hairs presented in the crime scene are commonly encountered as trace evidence. However, short tandem repeat (STR) profiling of the hairs currently have low and limited use due to poor success rate. To increase the success rate of STR profiling of telogen hairs, we developed a rapid and cost-effective method to estimate the number of nuclei in the hair roots. Five cationic dyes, Methyl green (MG), Harris hematoxylin (HH), Methylene blue (MB), Toluidine blue (TB), and Safranin O (SO) were evaluated in this study. We conducted a screening test based on microscopy and the percentage of loss with nuclear DNA, in order to select the best dye. MG was selected based on its specific nuclei staining and low adverse effect on the hair-associated nuclear DNA. We examined 330 scalp and 100 pubic telogen hairs with MG. Stained hairs were classified into five groups and analyzed by STR. The fast staining method revealed 70% (head hair) and 33.4% (pubic hair) of full (30 alleles) and high partial (18-29 alleles) STR profiling proportion from the lowest nuclei count group (one to ten nuclei). The results of this study demonstrated a rapid, specific, nondestructive, and high yield DNA profiling method applicable for screening telogen hairs.
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