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Promega announces its new Differex™ System that separates sperm
from epithelial cells in the forensic investigation of sexual assault
samples using an easy and rapid format. With Differex, the differential
extraction process, including DNA purification, takes two hours
for most samples compared to six or more hours with the current
method.
“This is the first major change to this technique since it was
developed 20 years ago,” says Allan Tereba, Differex lead research
scientist. “Differex provides a way to process sexual assault samples
in a high-throughput format and finally gives the community the
means to significantly reduce the existing backlog of hundreds of
thousands of rape kits.” A 96-well unit for automation of differential
extraction is currently in development.
The Differex method involves a proteinase K-selective digestion
of epithelial cells, followed by differential centrifugation and
phase separation. After the differential centrifugation, two phases
exist. The lower phase consists of the clear, nontoxic organic Separation
Solution, which separates the sperm pellet at the bottom of the
tube from the soluble female DNA in the upper aqueous phase.
A yellow dye in the aqueous phase facilitates the removal of
this phase. Once the aqueous phase containing the soluble DNA is
removed, the tube and Separation Solution are washed to remove any
residual soluble DNA without the need for a second centrifugation.
The result is epithelial and sperm fractions with minimal carry-over
in a fraction of the time required by current differential extraction
techniques.
For more information on the Differex Differential Extraction System, please visit the Differex Product Profile page.
About Promega
Promega Corporation is a leader in providing innovative solutions
and technical support to the life sciences industry. The company’s 1,450 products enable scientists worldwide to advance their knowledge
in genomics, proteomics, cellular analysis, molecular diagnostics
and human identification. Founded in 1978, the company is headquartered
in Madison, WI, USA with branches in twelve countries and 54 global
distributors. Annual sales exceed $165 million.
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