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User Forum

Please feel free to share your experiences with the Erase Kit and discuss Erase with other users. If you have questions about the product or ordering process, please use the "Contact Us" link instead.

Shelly Beckwith
Fri, 2011-07-08 13:43
We welcome each of you to the Erase users group. We will continually strive to improve the Erase kit and hope that each of you will share your successes, difficulties and solutions with each other in this forum.


2 comments on User Forum

  • Bellator

    Has anybody else had problems removing the female fraction from the sperm fraction? My nuclease step failed to work; having followed the protocol I had expected - at the very least - for the female element to be removed from the male fraction.

  • Christian Carson

    Bellator, it was good to speak with you in person. The problem is not with the Erase reagents, but due to damaged sperm cells in the semen used to prepare mock sexual assault samples. First, it is important to note that it is remarkable how long sperm cells remain intact well enough for DNA analysis in the human vaginal tract. Samples collected as much as (and more than) 2 days post coitus are successfully extracted using Erase. However, when preparing mock samples in the laboratory, the semen needs to be fresh or fresh frozen. Sperm cells in semen diluted in water break down with time allowing the nuclease to damage their DNA before its time to lyse them. To dilute semen, use fresh semen and 1X PBS. Make the dilutions and place the diluted semen onto a substrate (swab) to dry as soon as possible. Once the sperm cells are dry, they are ready to be used in Erase. Do not use semen or semen dilutions that have been stored in solution at 4C or room temperature for more than a day. Semen can be frozen and thawed one time, but multiple freeze/thaw cycles will destroy the integrity of the sperm cells. Neat semen can be divided into aliquots and frozen for future use, but only use each aliquot one time - one thaw. When post coital samples or mock samples from fresh semen are extracted with Erase, no epithelial (female) DNA will be amplified in the male fraction. When the samples are damaged by dilution in water or by thawing them too many times, much of the sperm (male) DNA will be destroyed during the procedure, and what little bit of female DNA is left in the sample will be amplified. Thus, be sure to try genuine post coital samples when testing Erase to see how well it works. Then prepare semen following the rules described above when you are interested in carefully measured experiments.
    Christian Carson, PhD, Paternity Testing Corporation, ptclabs.com