Salivary deoxyribounuclease I polymorphism separated by polyacrylamide gel-isoelectric focusing and detected by the dried agarose film overlay method

Isoelectric focusing of whole saliva samples on polyacrylamide gels (pH 3.5–5), followed by dried agarose film overlay detection, was employed to determine the type of salivary deoxyribonuclease I (DNase I). Since this detection method had not only a high sensitivity, but also a high band resolution, it was possible to determine DNase I types from saliva samples of 2–5 μL. Pretreatment of saliva samples with neuraminidase simplified the isozyme pattern and enhanced the sensitivity. The DNase I types in all 30 saliva samples showed a good correlation with the types found in the corresponding blood, semen, and urine samples. This preliminary trial indicates that DNase I typing from saliva samples is a new and promising method for individualization of casework samples in the field of forensic biology.