SCIENCE TEST

Researchers at WCU are helping evaluate the next generation of DNA sequence analysis

By TERESA KILLIAN TATE

The studies that forensic science faculty members are planning for Western Carolina’s new state-of-the-art DNA sequencers could help introduce the technology into crime laboratory casework across the nation. The university recently acquired two instruments believed to generate significantly more DNA information from a test sample than the fluorescence-based chemistries and equipment that have been used for years in crime laboratories. Before the new technology can be reliably used in criminal investigations, however, exploratory studies must be conducted. And that’s where WCU comes in, said Mark Wilson, director of the forensic science program.

Rebecca Malott ’10 performs a DNA extraction from buccal
cells with guidance from Brittania Bintz MS ’06 (background),
forensic research scientist at WCU.

“These instruments are most common in genome laboratories and have not yet made a debut in forensic science, but it’s just a matter of time,” said Wilson. “There is a lot of discussion in the forensic science community about how to integrate this technology into forensic casework. We will conduct some of the studies at WCU that are required for this kind of equipment to be introduced into crime laboratories so that the benefits of the new technology can be realized.”

The new instruments use light signals to generate DNA sequence information on a very fine scale. Specifically, the equipment’s charge-coupled device, or CCD camera, takes pictures of light emitted from microscopic wells containing the DNA sequencing reagents and the DNA template to be sequenced. The pictures generated resemble a snowy TV screen, with each pixel representing a separate DNA sequencing reaction. The small pieces of DNA sequence are collected and then stitched together using computer programs to build larger sequences so that investigators can compare the results with other DNA sequences from a particular case or a database.

“This approach assists with the difficult task of evaluating mixtures of different DNA sequences, such as those found in some evidentiary samples, or those found, for instance, from a soil sample containing multiple bacterial species from the Great Smoky Mountains,” said Wilson. “There are a multitude of different uses for this technology that expand beyond forensic science into widely divergent fields within biology.”

The sequencer will be available for use in research by WCU faculty in a range of disciplines, including biology and chemistry, and students will benefit from becoming familiar with the equipment, said Wilson. “Our students will be exposed to a technology that is just now coming into the forefront,” he said. “They will gain valuable experience that is not offered in many undergraduate programs, especially in forensic science.”

The forensic science program also recently received a $397,098 grant from the National Institute of Justice to evaluate an emerging method of DNA sequence analysis using these instruments. The method, called deep sequencing, can identify minor variations within a DNA sequence that are present as a small percentage of the whole. Using deep sequencing information from hair, mouth and blood samples, WCU’s research will attempt to reveal whether the forensic field might benefit in making interpretational changes in some aspects of human DNA analysis. “This research may have an impact on the number of interpretations that are currently inconclusive,” Wilson said. “In other words, it may result in more definitive conclusions, although this remains to be seen.”