Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Pickrahn, I.
STR-typing of single cells in forensic DNA analysis.
[ Diplomarbeit/Master Thesis ] Paris-Lodron University of Salzburg; 2011. pp.101.
- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Kroneis Thomas
- Altmetrics:
- Abstract:
- The identification of an unknown individual such as an assailant in sexual assault cases or an unknown dead person is one of the major tasks in forensic investigation. In the past decades, multiplex short tandem repeat-typing (STR-typing) has become a powerful tool for the identification of individuals. Although the methods for obtaining an STR-profile have been improved within the years, there are still limitations, especially in cases with low amounts of DNA and degraded samples. Additionally, samples that originate from more than one individual, which usually occurs in cases of sexual violation, often result in mixed profiles that are difficult to interpret. In this study, differential extraction, the gold standard for the separation of vaginal epithelial cells from the victim and sperm cells from the perpetrator before standard STR-typing was evaluated in relation to the limitations of this method. In addition, a protocol for low-volume on-chip analysis of single sperm cells isolated by means of laser microdissection and pressure catapulting (LMPC) was developed. The results were used to compare this method with the standard differential extraction. Furthermore, the application of an additional whole genome amplification (WGA) step was tested in a further experiment. The results of this study demonstrate that the new applied low-volume on-chip method is able to outperform the gold standard of differential extraction analysing samples containing low amounts of sperm cells since partial STR-profiles can be obtained from as little as a single sperm cell. Single sperm cells can be selectively isolated using LMPC and template loss is avoided using a single reaction platform for all reactions. The additional iWGA step results in a reduced genotyping success during this experiment, indicating that the used iWGA kit will remain inappropriate for this experimental setup unless further improvement and evaluation is done.