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Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis

Samples for forensic DNA analysis are often collected from a wide variety of objects using cotton or nylon tipped swabs. Testing has shown that significant quantities of DNA are retained on the swab, however, and subsequently lost. When processing evidentiary samples, the recovery of the maximum amo...

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Autores principales: Adamowicz, Michael S., Stasulli, Dominique M., Sobestanovich, Emily M., Bille, Todd W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4280208/
https://www.ncbi.nlm.nih.gov/pubmed/25549111
http://dx.doi.org/10.1371/journal.pone.0116351
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author Adamowicz, Michael S.
Stasulli, Dominique M.
Sobestanovich, Emily M.
Bille, Todd W.
author_facet Adamowicz, Michael S.
Stasulli, Dominique M.
Sobestanovich, Emily M.
Bille, Todd W.
author_sort Adamowicz, Michael S.
collection PubMed
description Samples for forensic DNA analysis are often collected from a wide variety of objects using cotton or nylon tipped swabs. Testing has shown that significant quantities of DNA are retained on the swab, however, and subsequently lost. When processing evidentiary samples, the recovery of the maximum amount of available DNA is critical, potentially dictating whether a usable profile can be derived from a piece of evidence or not. The QIAamp DNA Investigator extraction kit was used with its recommended protocol for swabs (one hour incubation at 56°C) as a baseline. Results indicate that over 50% of the recoverable DNA may be retained on the cotton swab tip, or otherwise lost, for both blood and buccal cell samples when using this protocol. The protocol’s incubation time and temperature were altered, as was incubating while shaking or stationary to test for increases in recovery efficiency. An additional step was then tested that included periodic re-suspension of the swab tip in the extraction buffer during incubation. Aliquots of liquid blood or a buccal cell suspension were deposited and dried on cotton swabs and compared with swab-less controls. The concentration of DNA in each extract was quantified and STR analysis was performed to assess the quality of the extracted DNA. Stationary incubations and those performed at 65°C did not result in significant gains in DNA yield. Samples incubated for 24 hours yielded less DNA. Increased yields were observed with three and 18 hour incubation periods. Increases in DNA yields were also observed using a swab re-suspension method for both cell types. The swab re-suspension method yielded an average two-fold increase in recovered DNA yield with buccal cells and an average three-fold increase with blood cells. These findings demonstrate that more of the DNA collected on swabs can be recovered with specific protocol alterations.
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spelling pubmed-42802082015-01-07 Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis Adamowicz, Michael S. Stasulli, Dominique M. Sobestanovich, Emily M. Bille, Todd W. PLoS One Research Article Samples for forensic DNA analysis are often collected from a wide variety of objects using cotton or nylon tipped swabs. Testing has shown that significant quantities of DNA are retained on the swab, however, and subsequently lost. When processing evidentiary samples, the recovery of the maximum amount of available DNA is critical, potentially dictating whether a usable profile can be derived from a piece of evidence or not. The QIAamp DNA Investigator extraction kit was used with its recommended protocol for swabs (one hour incubation at 56°C) as a baseline. Results indicate that over 50% of the recoverable DNA may be retained on the cotton swab tip, or otherwise lost, for both blood and buccal cell samples when using this protocol. The protocol’s incubation time and temperature were altered, as was incubating while shaking or stationary to test for increases in recovery efficiency. An additional step was then tested that included periodic re-suspension of the swab tip in the extraction buffer during incubation. Aliquots of liquid blood or a buccal cell suspension were deposited and dried on cotton swabs and compared with swab-less controls. The concentration of DNA in each extract was quantified and STR analysis was performed to assess the quality of the extracted DNA. Stationary incubations and those performed at 65°C did not result in significant gains in DNA yield. Samples incubated for 24 hours yielded less DNA. Increased yields were observed with three and 18 hour incubation periods. Increases in DNA yields were also observed using a swab re-suspension method for both cell types. The swab re-suspension method yielded an average two-fold increase in recovered DNA yield with buccal cells and an average three-fold increase with blood cells. These findings demonstrate that more of the DNA collected on swabs can be recovered with specific protocol alterations. Public Library of Science 2014-12-30 /pmc/articles/PMC4280208/ /pubmed/25549111 http://dx.doi.org/10.1371/journal.pone.0116351 Text en https://creativecommons.org/publicdomain/zero/1.0/ This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration, which stipulates that, once placed in the public domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.
spellingShingle Research Article
Adamowicz, Michael S.
Stasulli, Dominique M.
Sobestanovich, Emily M.
Bille, Todd W.
Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis
title Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis
title_full Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis
title_fullStr Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis
title_full_unstemmed Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis
title_short Evaluation of Methods to Improve the Extraction and Recovery of DNA from Cotton Swabs for Forensic Analysis
title_sort evaluation of methods to improve the extraction and recovery of dna from cotton swabs for forensic analysis
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4280208/
https://www.ncbi.nlm.nih.gov/pubmed/25549111
http://dx.doi.org/10.1371/journal.pone.0116351
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