PCR typing of human semen stains after SEM-EDX examination

There is an increasing demand to use scanning electron microscopy in the fo rensic analysis of biological samples. Such analyses are routinely used for the investigation of blood stains, seminal stains, diatoms, residues on wo unds and residues and trace elements in gunshot powder. The same samples ar e sometimes also required for identification via DNA analysis, e.g. blood s tains, seminal stains or epidermal cells. The ionising radiation provokes d amage to DNA and also to membrane and proteine structure, The question ther efore arises whether the usual sequence of such an investigation, i.e. prio r application of SEM and afterwards analysis of DNA, can affect the success rate of the DNA analysis. We have therefore experimentally exposed semen s amples to a defined electron beam for different time intervals varying betw een 1 and 25 min and afterwards performed quantitative and qualitative DNA analysis. Our studies revealed that sample treatment with an electron beam does not interfere with subsequent DNA typing by various currently used for ensic PCR systems.