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DNA Recovery From Semen Swabs with the DNA IQ System

NCJ Number
Maria Fernanda Lazzarino; Andrea Colussi; Maria Mercedes Lojo
Date Published
January 2008
3 pages
This report describes a procedure that increases DNA yield in extraction from sperm swabs.
After extraction from sperm swabs using the DNA IQ System (Promega, Madison, WI) following the suggested protocol for sperm-containing samples (Promiga 2006) with slight modifications, a fraction of the sperm cells are retained in the solid support. The experimental results described in this report show that the incubation in the lysis buffer at 95 degrees centigrade for 30 minutes prior to resin extraction improves DNA yield from a sperm swab. Amplicon signals in the GeneScan Analysis Software Version 3.1 data display showed that after the extraction, almost 20 to 30 percent of the male profile remained attached to the solid matrix, as indicated by the observed difference in the mean peak area. The incubation step in the lysis buffer at 95 degrees centigrade for 30 minutes in the presence of the solid support (cotton swab) thus helps release male DNA, such that the yield is improved. In the procedure used, a cotton swab was embedded with 100 ml of a dilution of a semen sample from a volunteer donor and placed onto a Petri dish. Half of the swab was processed according to the protocols recommended for sperm-containing samples, with slight modification, i.e., the matrix was maintained during the whole process and the dithiothreitol (DTT) concentration in the lysis buffer was raised threefold (3 ml DTT 1.0 m per 100 ml of buffer). The remaining cotton support was then extracted with 200 ml of chelex 100 added to 1 ml of proteinase K (20 mg/ml) and 7 ml DTT (1.0 m). DNA samples were typed with the AmpFlSTR Profiler Plus kit and analyzed on an ABI Prism 310 Genetic analyzer. 1 table and 2 references