出生前親子鑑定

Methods for extracting DNA from toothbrushes.

NIPPT　歯ブラシに付着するDNAの抽出方法

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Summary of this article

Describes how to extract DNA from toothbrushes. From basic procedures that can be done at home to highly accurate and specialized methods, this section explains in detail.

The extraction of DNA from toothbrushes is usually used for forensic investigations or individual identification. The general procedure is described below.

1. Sample collection

Toothbrushes are likely to contain DNA due to the presence of oral cells and saliva on them. Collect samples promptly after use of the toothbrush and store in a clean container. Storage should be in dry conditions to prevent DNA degradation.

2. Cell collection

To extract DNA from cells and saliva on the bristles of a toothbrush, the following steps are taken

  • Cell flushing: wash the bristles of the toothbrush with an appropriate buffer solution (e.g. TE buffer or PBS).This process transfers the cells adhering to the brush into the solution. By immersing the entire toothbrush in the cleaning solution and allowing it to sit for some time, the cells are efficiently collected.
  • Centrifugation: the wash solution is collected and the cells are collected as pellets using a centrifuge. The pellet is the starting point for DNA extraction.

3. Cell lysis (degradation)

Lysis buffer (e.g. buffer used with proteinase K) is added to the collected cell pellets to disrupt the cell membrane and release the DNA. This process is carried out by incubating the cells in a warm water bath (e.g. 56°C) for several hours. This destroys the nuclei in the cells and releases the DNA into solution.

4. DNA extraction

After lysis, the following methods are used to recover DNA

  • Phenol-chloroform extraction: to separate DNA and proteins, an organic extraction is performed using phenol and chloroform. The upper aqueous phase then contains the DNA.
  • Commercial DNA extraction kits: there are a number of commercial kits available for efficient DNA recovery, which can be used to extract DNA quickly and easily.

5. purification of DNA.

Extracted DNA may contain impurities. To remove these, DNA is purified using ethanol precipitation or other methods to obtain pure DNA. In this process, the DNA is precipitated to remove impurities.

6. Amplification and analysis of DNA

As the DNA obtained is usually small in quantity or fragmented, PCR (polymerase chain reaction) is used to amplify specific DNA regions and increase them to the required quantity. The amplified DNA is then further analyzed and used to identify individuals or confirm genetic relationships.

Summary

The process of extracting DNA from toothbrushes is based on the collection of cells and saliva from the brush part, followed by appropriate lysis, extraction and purification processes. This method is an important technique used in forensic science, paternity testing and other genetic testing.

医師監修 監修日：2024年8月28日

岡 博史 （おか ひろし）

医師・医学博士 ／ ヒロクリニック統括院長

YouTubeチャンネルなどを通じて、遺伝子やNIPT（新型出生前診断）についてわかりやすく発信しています。

略歴

  • 1996年 慶應義塾大学医学部 卒業
  • 2004年 慶應義塾大学 医学博士号 取得
  • 2005年 慶應義塾大学 皮膚科学教室 助手
  • 2008年 ヒロ皮フ形成クリニック 開業
  • 2009年 医療法人社団福美会 理事長
  • 2015年 医療法人社団福美会 理事

資格・所属

  • CAPラボディレクター
  • 日本皮膚科学会 皮膚科専門医
  • 日本医師会 産業医
  • 東京衛生検査所 指導監督医

発信・関連リンク

この記事は、 ヒロクリニックNIPPTの編集・監修体制 にもとづき、資格を持つ医師が内容を確認しています。

医師監修 監修日：2024年8月28日

堤 修一 （つつみ しゅういち）

医師・医学博士 ／ ヒロクリニック博多駅前院 院長

略歴

  • 1993年 東京大学医学部医学科 卒業
  • 2016〜2019年 東京大学先端科学技術研究センター 准教授

発信・関連リンク

この記事は、 ヒロクリニックNIPPTの編集・監修体制 にもとづき、資格を持つ医師が内容を確認しています。

参考文献

  1. Tanaka M, Yoshimoto T, Nozawa H, Ohtake E, Hasegawa S, Itoh T, et al. Usefulness of toothbrushes as a source of DNA for individual identification. J Forensic Sci. 2000 May;45(3):671-5.
  2. Burger M, Demmelmeyer H, Szilvassy C. Extraction of DNA from toothbrushes. Forensic Sci Int. 2005 Jul 16;151(2-3):271-4.
  3. Tobe SS, Watson N, Nic Daeid N. Evaluation of DNA extraction methods for forensic toothbrush samples. Sci Justice. 2007 Jun;47(2):68-74.
  4. Walsh PS, Metzger DA, Higuchi R. Chelex 100 as a medium for simple extraction of DNA for PCR-based typing from forensic material. Biotechniques. 1991 Apr;10(4):506-13.
  5. Kennedy L, Thornton L, O'Donnell C. Retrieval of DNA profiles from toothbrushes. J Forensic Sci. 2001 Nov;46(6):1443-6.

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Supervisor of the article

Dr. Hiroshi Oka

Director of CAP Laboratory

Graduated from Keio University, Faculty of Medicine

Doctor of Medicine

Medical Doctor