When Dr. Victor Ugaz talks about "catch-and-release," he means DNA, not fish. DNA is known to most of us these days through crime shows, but crime scene investigators and police detectives aren't the only ones who use DNA analysis. DNA identification is also used to diagnose diseases or detect biological agents and toxins. Ugaz, an assistant professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University, is working to miniaturize a sprawling DNA lab so that components needed for DNA analysis are available in a tiny lab-on-a-chip about the size of a business card.
He's already worked out a novel scheme to perform the series of reactions that allow scientists to rapidly copy the often trace amounts of DNA for analysis. Now, in a paper in the March 28 issue of the Proceedings of the National Academy of Sciences (Vol. 103 No. 13, 4825-4830), Ugaz and Ph.D. student Faisal A. Shaikh have retreated a step: isolating and concentrating small amounts of DNA that would otherwise be difficult to analyze.
"We've found a way to take a dilute DNA sample and concentrate it," Ugaz said. "A lot of times, the genomic material you're looking for is in your sample but at very low concentrations. Using our device, DNA can be concentrated to a much higher level so we can detect it more easily."
In the paper, "Collection, focusing and metering of DNA in microchannels using addressable electrode arrays for portable low-power bioanalysis," Ugaz and Shaikh present their scheme for concentrating and focusing a minute sample of DNA in tiny spaces called microchannels.
The scheme involves placing a series of small electrodes at set intervals along the bottom of a microchannel. A DNA sample is injected into the channel and a small voltage (1 Volt) is applied across the first pair of electrodes in the series. Because opposites attract, the negatively charged DNA migrates toward the positively charged anode and accumulates there, making it possible to "catch" the DNA sample. Switching off the voltage and reapplying it between the second and third electrodes will then "release" the DNA allowing it to be collected at the third electrode.
By repeating this sequential catch and release process, the DNA concentration can be progressively increased. Labeling the sample with a fluorescent dye allows the stepwise increase in concentration from electrode to electrode to be directly observed. After enough catch-and-release steps have been performed to raise the concentration to a desired level, the collected DNA can then be dispensed and used to perform a variety of analysis tests.
And all on a device the size of a business card.
"We're working on developing the components needed to build miniaturized lab-on-a-chip devices" Ugaz said. "The simplicity of this design makes it attractive for portable and inexpensive analysis systems that could be used in areas where there's no access to large DNA labs."
Source: Texas A&M University
Related stories:
How plants fine tune their natural chemical defenses
Even closely related plants produce their own natural chemical cocktails, each set uniquely adapted to the individual plant's specific habitat. Comparing anti-fungals produced by tobacco and henbane, researchers at the Salk Institute for Biological Studies discovered that only a few mutations in a key enzyme are enough to shift the whole output to an entirely new product mixture. Making fewer changes led to a mixture of henbane and tobacco-specific molecules and even so-called "chemical hybrids," explaining how plants can tinker with their natural chemical factories and adjust their product line to a changing environment without shutting down intracellular chemical factories completely.
Creating lung cancer risk models for specific populations refines prediction
Lung cancer risk prediction models are enhanced by taking into account risk factors by race and by measuring DNA repair capacity, according to research teams led by epidemiologists at The University of Texas M. D. Anderson Cancer Center in two complementary papers appearing in the September issue of
Cancer Prevention Research.
Studies spot numerous undiscovered gene alterations in pancreatic and brain cancers
HHMI investigators have detected a multitude of broken, missing, and overactive genes in pancreatic and brain tumors, in the most detailed genetic survey yet of any human tumor. Some of these genetic changes were previously unknown and could provide new leads for improved diagnosis and therapy for these devastating cancers.
Researchers pinpoint geographic origins of individuals using DNA
(PhysOrg.com) -- One day soon, you may be able to pinpoint the geographic origins of your ancestors based on analysis of your DNA.
Gene associated with pair-bonding in animals has similar effects in human males
Variation in the gene for one of the receptors for the hormone vasopressin appears to be associated with how human males bond with their partners, according to an international team of researchers.
DNA Barcodes: Are They Always Accurate?
(PhysOrg.com) -- DNA barcoding is a movement to catalog all life on earth by a simple standardized genetic tag, similar to stores labeling products with unique barcodes. The effort promises foolproof food inspection, improved border security and better defenses against disease-causing insects, among many other applications.
Study: DNA barcoding in danger of 'ringing up' wrong species
DNA barcoding is a movement to catalog all life on earth by a simple standardized genetic tag, similar to stores labeling products with unique barcodes. The effort promises foolproof food inspection, improved border security, and better defenses against disease-causing insects, among many other applications.
Rapid test for pathogens developed by K-State researchers
Dangerous disease often spreads faster than it takes to diagnose it in the lab. To remedy that, researchers at Kansas State University have developed a test to bring that time from days down to hours.
