A pressure-based protocol for differential extraction has been optimized to provide a rapid and selective alternative to conventional differential extraction techniques with the advantage of an increased recovery of genomic DNA. The protocol involves treating cotton swabs containing mixtures of sperm and vaginal epithelial cells with two sets of pressure treatment using a Barocycler® NEP 2320 in alkaline conditions. This first step quantitatively and selectively removes female epithelial cells. The cotton swab is removed and further treated with alkali at 95°C for the removal of sperm cell DNA. The resultant solution provides a clean male profile at a 20:1 cell ratio. Furthermore, the inclusion of a pretreatment step involving immunomagnetic cell capture of the female cells, permits nearly complete isolation of male sperm cells at cell ratios of up to 200:1 female to male cells.
Keywords: Alkaline lysis; DNA typing; Differential extraction; Immunocapture; Pressure cycling; Short tandem repeat.
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.