Evaluation of different methods for identification of seminal stains

Identification of seminal stains is critical in the evaluation of sexual assault victims, as it is the most important evidence in sexual crimes. The aim of the present study was to evaluate zinc [Zn], acid phosphatase [AP] and seminal vesicle specific antigen [SVSA] as marker in identification of seminal stains. The study was carried out on 60 seminal stains samples taken from normo and azoospermic men. Zn and AP were detected by spot tests and SVSA was tested by ELISA technique. The tests were repeated on the stains at different storage periods up to 2 years at room temperature. Postcoital vaginal swabs and stains at different body fluids [urine, serum, saliva] were also included in the study. The study revealed that Zn and SVSA were more specific semen markers than AP, yet Zn was more stable in the stains as it detected seminal stain samples stored up to 2 years and semen in vaginal swabs up to 5 days postcoital. All the studied semen markers were able to detect normo and azoospermic semen with no significant difference

P C R amplification of D N A extracted from old human bones

The forensic analysis of DNA enables the identification of an individual based on molecular evidence left at the scene of the crime. The DNA polymorphisms are detected either by restriction fragment length polymorphisms [RFLPs] or by polymerase chain reaction [PCR], which allowed for detection of genetic markers in samples containing as little as 2 ng of DNA. Many studies have been conducted on the stability of DNA obtained from postmortem tissues and organs other than blood including bones and teeth. The aim of the present work was to verify the medicolegal importance of amplification of DNA extracted from human bones as a tool of identification of unidentifiable human remains. The present study was conducted on 35 bone specimens and 5 complete teeth. All specimens were at least 20 years old. DNA was extracted by the organic phenol-chloroform method. The quality and quantity of extracted DNA was assessed by running yield gels. The Quanti Blot Human Quantitation kit supplied by Perkin Elmer was used for quantitation of human DNA by hybridization of biotimiated oligonucleotide probe [D17Z1] to DNA samples immobilized to a Pall- Biodyne nylon membrane. DNA amplification was done using Perkin Elmer 480 DNA thermal cycler. Typing for the six loci [DQAI, LDLR, GYPA, HBGG, D7S8 and GC] was performed by hybridization of the amplified PCR products to the DNA probe strips. DNA was successfully extracted from 35 specimens [87.50%], and out of these samples 6 samples [17.14%] showed a significant amount of degraded DNA. DNA yields were higher in spongy bone than in compact bone. Out of 35 samples 32 [01.43%] were successfully amplified and typed for the six mentioned loci