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Garvin A.M.,Confarma France SARL | Fischer A.,Crime Laboratory | Schnee-Griese J.,Crime Laboratory | Jelinski A.,Crime Laboratory | And 7 more authors.
Investigative Genetics | Year: 2012

Background: Profiling sperm DNA present on vaginal swabs taken from rape victims often contributes to identifying and incarcerating rapists. Large amounts of the victim's epithelial cells contaminate the sperm present on swabs, however, and complicate this process. The standard method for obtaining relatively pure sperm DNA from a vaginal swab is to digest the epithelial cells with Proteinase K in order to solubilize the victim's DNA, and to then physically separate the soluble DNA from the intact sperm by pelleting the sperm, removing the victim's fraction, and repeatedly washing the sperm pellet. An alternative approach that does not require washing steps is to digest with Proteinase K, pellet the sperm, remove the victim's fraction, and then digest the residual victim's DNA with a nuclease.Methods: The nuclease approach has been commercialized in a product, the Erase Sperm Isolation Kit (PTC Labs, Columbia, MO, USA), and five crime laboratories have tested it on semen-spiked female buccal swabs in a direct comparison with their standard methods. Comparisons have also been performed on timed post-coital vaginal swabs and evidence collected from sexual assault cases.Results: For the semen-spiked buccal swabs, Erase outperformed the standard methods in all five laboratories and in most cases was able to provide a clean male profile from buccal swabs spiked with only 1,500 sperm. The vaginal swabs taken after consensual sex and the evidence collected from rape victims showed a similar pattern of Erase providing superior profiles.Conclusions: In all samples tested, STR profiles of the male DNA fractions obtained with Erase were as good as or better than those obtained using the standard methods. © 2012 Garvin et al.; licensee BioMed Central Ltd. Source


Garvin A.M.,Confarma France SARL | Fritsch A.,Confarma France SARL
Journal of Forensic Sciences | Year: 2013

Regenerated cellulose filters are used for concentrating and purifying genomic DNA from casework samples, due to the high yields and low retentate volumes that these filters provide. The Millipore Ultracel YM-100 is an example of this filter type and has been available to the forensics community for this application since 1990. In 2002, Millipore introduced the Amicon line of vertical filters that provide a larger area for filtration and have a dead space to prevent spinning to dryness. In the present study, Amicon filters were optimized in terms of g force and spin times for their ability to concentrate and purify genomic DNA. The Amicon Ultra 0.5 mL 30 K was used with mock forensic samples containing as little as 160 buccal cells, 20 nL of blood, or 8 nL of semen. In conclusion, the Amicon line of filters can be used to purify genomic DNA from small numbers of cells. © 2012 American Academy of Forensic Sciences. Source


Garvin A.M.,Confarma France SARL | Holzinger R.,Confarma France SARL | Berner F.,University of Zurich | Krebs W.,University of Zurich | And 5 more authors.
BioMed Research International | Year: 2013

Biological samples are vulnerable to degradation from the time they are collected until they are analysed at the laboratory. Biological contaminants, such as bacteria, fungi, and enzymes, as well as environmental factors, such as sunlight, heat, and humidity, can increase the rate of DNA degradation. Currently, DNA samples are normally dried or frozen to limit their degradation prior to their arrival at the laboratory. In this study, the effect of the sample drying rate on DNA preservation was investigated, as well as a comparison between drying and freezing methods. The drying performances of two commercially available DNA collection tools (swab and drying tube) with different drying rates were evaluated. The swabs were used to collect human saliva, placed into the drying tubes, and stored in a controlled environment at 25°C and 60% relative humidity, or frozen at -20°C, for 2 weeks. Swabs that were stored in fast sample drying tubes yielded 95% recoverable DNA, whereas swabs stored in tubes with slower sample drying rates yielded only 12% recoverable DNA; saliva stored in a microtube at -20°C was used as a control. Thus, DNA sampling tools that offer rapid drying can significantly improve the preservation of DNA collected on a swab, increasing the quantity of DNA available for subsequent analysis. © 2013 Alex M. Garvin et al. Source

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