DEOXYRIBONUCLEASE-I (DNASE-I) TYPING FROM SEMEN STAINS - LOW ENZYME-ACTIVITY IN VAGINAL FLUIDS DOES NOT INTERFERE WITH SEMINAL DNASE-I TYPING FROM MIXTURE STAINS

We describe the use of deoxyribonuclease I (DNase I) polymorphism for individualization of semen in body fluid stain mixtures, as a means of providing new and more useful information to practicing forensic biol ogists as a genetic marker. We have already reported that human DNase I isozyme patterns from different subjects are classifiable into ten g roups. Isoelectric focusing of DNase I isozymes on polyacrylamide gel (IEF-PAGE, pH 3.5 to 5) was accomplished using a 0.5 mm thick gel. Pre treatment of semen samples with neuraminidase enhanced the isozyme ban d resolution and sensitivity. Activity detection using the dried agaro se film overlay (DAFO) procedure was reliable, sensitive and simple, w ith high resolution, and the phenotypes of DNase I were determined in semen stains of about 0.3 muL stored at room temperature for up to a y ear in most of the samples tested. The Dnase I types in semen stains w ere correlated with the types found in the corresponding blood and uri ne samples, although most of the vaginal fluid samples had no typable DNase I activity. This is considerably advantageous for seminal indivi dualization from body fluid mixture stains in criminal cases. An evalu ation of DNase I typing by IEF-PAGE and DAFO was also performed on cas ework samples submitted to our laboratory, and the results showed that DNase I was expected to be one of the most useful individualization m arker of semen in practical application.