P085 – Pre-ejaculatory Fluid: A Largely Unknown Body Fluid Characterized by High DNA Content and a Specific Proteome

11:13

Wednesday August 19^th

Station 17

Duration: 12 minutes

04. Forensic biology

Marlene Lienesch

The identification of forensically relevant body fluids plays a crucial role in the investigation of sexual assault cases. Results from forensic casework suggest that pre-ejaculatory fluid may be involved in sexual offenses. In these cases, samples tested positive with semen-specific rapid tests, although no spermatozoa were detected histologically. Additionally, high concentrations of DNA were detected in these samples. Pre-ejaculatory fluid, which is produced in the bulbourethral glands and secreted prior to ejaculation, remains poorly studied, and its exact composition is still unclear. As this body fluid can provide crucial evidence in cases where no ejaculation has occurred, its characterization, differentiation from other forensically relevant body fluids, and detection are essential for reconstructing potential sexual crimes. Using semen-specific rapid tests, DNA analysis, and proteomic profiling, this study aimed to better understand pre-ejaculatory fluid and identify differences from semen.

Pre-ejaculatory fluid samples from 65 healthy adult men were analyzed. Three semen specific rapid tests (RSID™-Semen, Seratec® PSA-Semiquant and Phosphatesmo KM) were performed. Confirmatory sperm analysis was performed using Sperm HY-Liter™ staining in combination with the Zeiss™ Axioscope 5 fluorescence microscope. DNA was extracted from rapid test cassettes and from remaining rapid test extracts for DNA quantification and STR-typing of the pre-ejaculatory fluid samples. Proteome analysis was performed with SYNAPT G2-Si mass spectrometer and Progenesis QI software (Waters Corp.) on semen und pre-ejaculatory fluid samples to compare the composition of the two body fluids.

All of the pre-ejaculatory fluid samples reacted negative to the presence of semenogelin (RSID™-Semen) and no spermatozoa were detected morphologically. The presence of prostate-specific antigen was detected in almost all of the pre-ejaculatory fluid samples (Seratec® PSA-Semiquant). The results indicating the presence of acid phosphatase were ambiguous. DNA quantification showed a significant DNA amount and complete STR profiles could be generated in the majority of the pre-ejaculatory fluid samples. Proteome analysis showed that the protein composition of semen and pre-ejaculatory fluid differ significantly. These results are promising for the subsequent development of a rapid antibody-based test to characterize pre-ejaculatory fluid, the overall aim of this study.

Authors

Marlene Lienesch (Institute of Legal Medicine, Germany)
Simone König (Service Unit Proteomics, University of Münster, Germany)
Doreen Ackermann (Service Unit Proteomics, University of Münster, Germany)
Marielle Vennemann (Institute of Legal Medicine, Germany)
Hannah Bauer (Institute of Legal Medicine, Germany)

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P085 – Pre-ejaculatory Fluid: A Largely Unknown Body Fluid Characterized by High DNA Content and a Specific Proteome

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