The effects of differential extraction conditions on the premature lysis of spermatozoa.

The purpose of this study was to determine the effect Proteinase K, sodium dodecyl sulfate (SDS), incubation times, and temperatures had on differential extraction efficiencies and the premature lysis of spermatozoa. The effect was measured using Quantifiler® Duo and Identifiler™ PCR Amplification kits, where the resultant male and female DNA concentrations and their ratios within the nonsperm- and sperm fractions (SFs) were determined. Comparisons between expected and observed ratios illustrate the quantity of female DNA in the SF increased when Proteinase K was absent during the initial incubation. Additionally, there is no indication of simultaneous sperm and epithelial cell lysis in the absence of DTT at Proteinase K concentrations ranging from 10 to 300 μg/mL. All other conditions exhibited minimal variation in DNA concentration. Therefore, despite the various protocols used for the differential lysis of cell mixtures encountered in casework, the method is robust and successful at most conditions.