Department of Forensic Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8510, Japan; Forensic Biology Unit, Scientific Crime Laboratory, Kanagawa Prefectural Police, 155-1 Yamashita-cho, Naka-ku, Yokohama, Kanagawa 231-0023, Japan.
Forensic Biology Unit, Scientific Crime Laboratory, Kanagawa Prefectural Police, 155-1 Yamashita-cho, Naka-ku, Yokohama, Kanagawa 231-0023, Japan.
Forensic Sci Int. 2020 Jan;306:110077. doi: 10.1016/j.forsciint.2019.110077. Epub 2019 Nov 26.
Forensic samples are commonly influenced by various environmental factors, including ultraviolet (UV) irradiation; thus, forensic applications of DNA repair (e.g., PreCR™, Restorase®) have been investigated, focusing on short tandem repeat typing. However, current DNA-based examinations are used for both human and body fluid identification. This study thus aims to clarify the efficacy of a DNA repair approach for Streptococcus salivarius DNA-based identification of saliva from UV-damaged samples. Artificial UV-damaged genomic DNA of S. salivarius, drop saliva stains, and buccal swabs were used to evaluate the effects of DNA repair on S. salivarius DNA detection by using PreCR™ repair reagent. To evaluate forensic applications, we prepared mock forensic samples by exposing them to environmental conditions. Melting curve analysis following real-time PCR was applied for qualitatively detecting S. salivarius DNA with a specific melting peak of 80.5°C±0.4°C (n=10, mean ± 3SD). Single PCR was used for quantitative and qualitative analyses, whereas dual PCR was used for S. salivarius DNA qualitative detection. DNA repair experiments using artificial UV-damaged samples revealed a significant increase of only the quantitative value of genomic DNA samples by DNA repair. Moreover, significant quantitative DNA repair effects were not observed in all mock forensic samples, indicating the limitations of DNA repair for actual cell-derived DNA samples. Whereas, differences of qualitative results (with or without detection) were generated for mock forensic samples; thus, we consider the DNA repair strategy as an additional approach for S. salivarius DNA-based identification of saliva from environmentally damaged evidence.
法医样本通常会受到各种环境因素的影响，包括紫外线（UV）照射；因此，人们研究了 DNA 修复（例如 PreCR™、Restorase®）在法医中的应用，主要集中在短串联重复序列分型上。然而，目前的 DNA 检测既用于人体鉴定，也用于体液鉴定。因此，本研究旨在阐明 DNA 修复方法在基于 S. salivarius DNA 的唾液鉴定中的功效，该方法用于鉴定经 UV 损伤的样本中的唾液。本研究使用 PreCR™修复试剂，评估了 DNA 修复对 S. salivarius DNA 检测的影响，使用了人工 UV 损伤的 S. salivarius 基因组 DNA、点唾液斑和口腔拭子。为了评估法医应用，我们通过暴露于环境条件来制备模拟法医样本。应用实时 PCR 后的熔解曲线分析定性检测 S. salivarius DNA，具有 80.5°C±0.4°C 的特定熔解峰（n=10，平均值±3SD）。单 PCR 用于定量和定性分析，而双 PCR 用于 S. salivarius DNA 定性检测。使用人工 UV 损伤样本进行的 DNA 修复实验表明，仅基因组 DNA 样本的定量值有显著增加。此外，在所有模拟法医样本中均未观察到 DNA 修复的显著定量效果，这表明 DNA 修复对于实际细胞衍生的 DNA 样本具有局限性。然而，模拟法医样本产生了定性结果（有或无检测）的差异；因此，我们认为 DNA 修复策略是基于 S. salivarius DNA 鉴定环境受损证据中唾液的另一种方法。
