All infidelity ID results are held in the strictest confidence; information is only released to the submitting party. Every question is answered with discretion and respect and we have scientists on staff to answer your questions; call us toll free at 866-344-8378.  Alternatively, you can e-mail your question to a staff scientist at scientist@paternityexperts.com.

Ultraviolet light Illumination - Short wave 254 nm/Long wave 365 nm

The use of ultraviolet (UV) light can be of great assistance in many forms of forensic investigation. Since body fluids like semen, saliva, perspiration and vaginal fluids are naturally fluorescent, the use of a UV light source offers a unique method for locating these stains. The dried bodily fluids will naturally fluoresce when illuminated with UV light source. We can then isolate the exact location of the stain(s) to test, instead of testing the entire, large pieces of evidence such as a mattress, a carpet, a sheet, an article of clothing, etc.

Biochemistry

One of the unique properties associated with semen is the presence of an enzyme called prostatic acid phosphatase (PAP). PAP is not a single enzyme but an array of related isoenzymes from a variety of sources. The PAP assay is a well-documented presumptive assay for the presence of semen (1-4). Acid phosphatase activity is 50-1000 times greater in human semen than in any other bodily fluid.  Unfortunately, the use of acid phosphatase as a marker for semen is compromised because the vagina is also a source of vaginal acid phosphatase. Since seminal and vaginal acid phosphatase can not discriminate, the only approach to differentiating semen in vaginal secretion is by quantitative analysis. Finding a significantly elevated acid phosphatase level is consistent with the presence of semen. For example, if semen is present the acid phosphatase assay is very robust and solution will immediately turn a deep purple color.  If the solution does not immediately turn purple or takes several minute to hour to turn color then you are more than likely detecting endogenous vaginal acid phosphatase and not semen.

Principle of enzyme-linked detection.

Immunology-Anti-p30

Unlike the presumptive acid phosphatase test biochemistry assay, the detection of the p30 antigen requires the presence of the protein without the need of the target to perform an enzymatic function. This aids in the identification of semen in aged evidence samples in which the acid phosphatase enzyme is functionally inactive.  Prostate specific antigen (PSA, also known as p30), is a glycoprotein produced by the prostatic gland and secreted into seminal plasma (fluid).  The p30 is secreted in seminal fluid at concentrations of  200,000 to 5.5 million ng per mL. The sensitivity of the p30 test is 4 ng/mL and therefore seminal fluid diluted up to 1 in a million can also be detected. This means we can detect semen in samples that have been rinsed or washed (without detergent). In addition, p30 protein is produced from a larger protein that is degraded to release the p30 protein.  Since the p30 is a product of protein degradation it is readily detected in very old samples and sample that have been stored in a plastic bags for a long periond. The detection of the p30 antigen in forensic samples is often helpful because it confirms the presence of semen even in samples that involve vasectomized or azospermic individuals.  The reported frequency of azospermia of 1-9% in seminal stains or swabs examined in sexual assault cases (1) can be expected to rise, since the frequency of contraceptive vasectomy has been estimated to be 750 000 to 1,000 000 per year in the United States (2).

Microscopy

Additionally, individual sperm heads can be accurately identified based on their morphological characteristics, using a phase contrast microscope and 20-100x magnification. An ideal, mature spermatozoon has an oval shaped head with a regular contour (4.0-5.0 mm long and 2.5-3.5 mm wide) with a pale anterior part (acrosome; 40-70% of the head area) and a darker posterior region. The length-to-width ratio of the head should be 1.50 to 1.75.  The sperm tail should be attached in a symmetrically situated fossa in the base of the head.  The base of the head should be broad and not arrow-like. Only one tail should be attached (about 45 mm long), not coiled, nicked or bent over itself. Immediately behind the head the first part of the tail, the mid piece, should be somewhat thicker (maximum width = 1 µm) and about 7-8 mm long.

Differential Lysis-DNA Profiles

Once a suspected sample has been identified to contain sperm it is often contaminated with other cell types.  The most common contaminating cells are the epithelial cells lining the vaginal wall, but can include epithelial cells from the mouth (buccal cells) and skin, as well as those found in urine.

DNA from contaminating epithelial cells can be removed using a procedure called a differential extraction (5), which takes advantage of unique properties associated with each cell type. In this procedure, the cells are removed from the suspected material by soaking them in a gentle solution.  Epithelial cell DNA is isolated under mild conditions that break open the epithelial cells but leave the sperm cells intact DNA.  The DNA in sperm can then be extracted using a more harsh extraction procedure.

Sample Submission
If you have your specimen ready to be tested, place in a paper sack or envelope.  DO NOT use a Ziploc® bag or any other plastic bag.  Download and print the information forms, completely fill them out and mail them with your payment to the address indicated on the forms.

Control profile: For the control profile use two clean Q-tips (swab).  Rub one swab on the inside of your left cheek.  Rub the other swab on inside of your right cheek.  Let the sample air-dry for 10-20 minutes. Place the samples in a paper envelope and label it control profile.

Information/Order form (PDF)
To view the order form you will need a copy of Adobe^® Acrobat^® Reader. If you have access to the Internet, please click here to download the file. Adobe Acrobat Reader is a free

References:
1. Brauner, P., "The Evidence Notwithstanding--A case Report on a Rape," Journal of Forensic Sciences, JFSCA, Vol. 37, No.1, Jan. 1992, pp.345-348
2. Brauner, P.& Gallili, N., "A Condom--the Critical Link in a Rape," Journal of Forensic Sciences, JFSCA, Vol. 38, No.5, September 1993, pp.1233-1236.
3. "Forensic Science Symposium On The Analysis of Sexual Assault Evidence", Proceedings, Forensic Science Research and Training Center, Laboratory Division, FBI Academy, Quantico, Virginia, 1983, July 6-8
4. McCloskey, K.L. & Muscillo, G.C. & Noordewier, B., "Prostatic Acid Phosphatase Activity in the Postcoital Vagina," Journal of Forensic Sciences, 1975, vol.20, p.630-636
5. Gill, P., Jeffreys, A.J., Werret, D.J., Nature 1985, 318, 577-579.