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Ye L, Liao L, Lan J, Huang L, Du J, Zhang X, Lun M, Zhu B, Liu C, Chen L. Temporal dynamics changes in the vaginal fluid microbiome: Implications for body fluid identification and estimating time since deposition (TsD) for forensics. Forensic Sci Int 2024; 364:112219. [PMID: 39270472 DOI: 10.1016/j.forsciint.2024.112219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2024] [Revised: 08/21/2024] [Accepted: 09/08/2024] [Indexed: 09/15/2024]
Abstract
Vaginal fluid analysis plays a crucial role in sexual assault investigations. However, vaginal fluid found at crime scenes is usually subject to a certain duration of exposure. This study thus aimed to assess the influence of different durations of exposure to indoor environment on the vaginal microbiota. The 16S rDNA high-throughput sequencing was used on vaginal fluid samples exposed for short-term (30 days) and long-term (240 days), respectively. Despite potential contamination from environmental microorganisms, particularly following long-term exposure, the results indicated that the vaginal microbiota after exposure was still dominated by Lactobacillus. Both in short-term and long-term exposure involving vaginal fluid, there were clusters with time-dependent characteristics, wherein the relative abundances of associated microbial genera showed a trend of increasing or decreasing over time. In addition, each bodily fluid presented with a unique array of dominant bacterial genera, enabling the differentiation of exposed vaginal fluid samples from other bodily fluids (semen, skin, saliva, feces) with a remarkable 98.75 % accuracy rate. Furthermore, the mean absolute error achieved by the long-term deposition time prediction model was 13.54 days. The mean absolute error for the short-term deposition time prediction model was notably lower, reaching just 2.05 days. In summary, this study investigates the variations in microbial communities within vaginal fluid subjected to different indoor exposure durations and explores their potential in body fluid identification and estimating the time since deposition, thereby contributing valuable supporting evidence in forensic investigations.
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Affiliation(s)
- Linying Ye
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Lili Liao
- Department of Public Health, The Fifth People's Hospital of Foshan Nanhai District, Foshan 528231, China
| | - Jiangwei Lan
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Litao Huang
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Jieyu Du
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Xiaofeng Zhang
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Miaoqiang Lun
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Bofeng Zhu
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China.
| | - Chao Liu
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China; Anti-Drug Technology Center of Guangdong Province, Guangzhou 510230, China.
| | - Ling Chen
- Guangzhou Key Laboratory of Forensic Multi-Omics for Precision Identification, School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China.
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Watanabe K, Yamagishi T, Toyomane K, Akutsu T. Validation of a novel fluorescent probe-based real-time PCR assay to detect saliva-specific unmethylated CpG sites for saliva identification. Leg Med (Tokyo) 2023; 63:102260. [PMID: 37094513 DOI: 10.1016/j.legalmed.2023.102260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/27/2023] [Accepted: 04/13/2023] [Indexed: 04/26/2023]
Abstract
The identification of saliva from forensic samples is often important to establish what happened at a crime scene, especially in sexual assault cases. Recently, CpG sites that are specifically methylated or unmethylated in saliva have been reported as markers for saliva identification. In this study, we designed a fluorescent probe-based real-time polymerase chain reaction (PCR) assay for analyzing the methylation status of two neighboring CpG sites, which we previously found were saliva-specifically unmethylated. Specificity analysis using various types of body fluid/tissue samples demonstrated a probe detecting the unmethylation of the two CpG sites reacted only to saliva DNA, indicating this probe as an all-or-nothing marker for the presence of saliva DNA. Sensitivity analysis demonstrated that the detection limit was 0.5 ng saliva DNA as input for bisulfite conversion, while we confirmed a negative effect of larger amounts of non-saliva DNA on sensitivity in the analysis of saliva-vaginal DNA mixtures. We finally validated the applicability of this test to swabs from licked skin and bottles after drinking as mock forensic samples in comparison with other saliva-specific markers. We confirmed the potential usefulness of this test for skin samples, from which a saliva-specific mRNA was not detected reliably, while the ingredients in several beverages might affect methylation analysis. Given the simplicity of real-time PCR as well as the high specificity and sensitivity of the test, we believe the developed method is suitable for routine forensic analysis and can play an important role in saliva identification.
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Affiliation(s)
- Ken Watanabe
- National Research Institute of Police Science, Chiba 277-0882, Japan.
| | | | - Kochi Toyomane
- National Research Institute of Police Science, Chiba 277-0882, Japan
| | - Tomoko Akutsu
- National Research Institute of Police Science, Chiba 277-0882, Japan
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Abstract
This review paper covers the forensic-relevant literature in biological sciences from 2019 to 2022 as a part of the 20th INTERPOL International Forensic Science Managers Symposium. Topics reviewed include rapid DNA testing, using law enforcement DNA databases plus investigative genetic genealogy DNA databases along with privacy/ethical issues, forensic biology and body fluid identification, DNA extraction and typing methods, mixture interpretation involving probabilistic genotyping software (PGS), DNA transfer and activity-level evaluations, next-generation sequencing (NGS), DNA phenotyping, lineage markers (Y-chromosome, mitochondrial DNA, X-chromosome), new markers and approaches (microhaplotypes, proteomics, and microbial DNA), kinship analysis and human identification with disaster victim identification (DVI), and non-human DNA testing including wildlife forensics. Available books and review articles are summarized as well as 70 guidance documents to assist in quality control that were published in the past three years by various groups within the United States and around the world.
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Affiliation(s)
- John M. Butler
- National Institute of Standards and Technology, Special Programs Office, 100 Bureau Drive, Mail Stop 4701, Gaithersburg, MD, USA
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Sijen T, Harbison S. On the Identification of Body Fluids and Tissues: A Crucial Link in the Investigation and Solution of Crime. Genes (Basel) 2021; 12:1728. [PMID: 34828334 PMCID: PMC8617621 DOI: 10.3390/genes12111728] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/26/2021] [Accepted: 10/26/2021] [Indexed: 12/13/2022] Open
Abstract
Body fluid and body tissue identification are important in forensic science as they can provide key evidence in a criminal investigation and may assist the court in reaching conclusions. Establishing a link between identifying the fluid or tissue and the DNA profile adds further weight to this evidence. Many forensic laboratories retain techniques for the identification of biological fluids that have been widely used for some time. More recently, many different biomarkers and technologies have been proposed for identification of body fluids and tissues of forensic relevance some of which are now used in forensic casework. Here, we summarize the role of body fluid/ tissue identification in the evaluation of forensic evidence, describe how such evidence is detected at the crime scene and in the laboratory, elaborate different technologies available to do this, and reflect real life experiences. We explain how, by including this information, crucial links can be made to aid in the investigation and solution of crime.
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Affiliation(s)
- Titia Sijen
- Division Human Biological Traces, Netherlands Forensic Institute, Laan van Ypenburg 6, 2497 GB The Hague, The Netherlands
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - SallyAnn Harbison
- Institute of Environmental Science and Research Limited, Private Bag 92021, Auckland 1142, New Zealand;
- Department of Statistics, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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