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Rapid DNA, RNA Capture Technique Devised

DNA analysis graphic

(Gerd Altmann, Pixabay)

22 November 2017. Researchers in Australia developed a simple and inexpensive dipstick technique that captures and purifies specimen samples for genetic analysis in about 30 seconds. A team from University of Queensland in Brisbane describes the technique, which can be adapted to field use outside the lab, in yesterday’s issue of the journal PLoS Biology.

The Queensland team led by plant scientist Jimmy Botella and postdoctoral researcher Michael Mason is seeking faster, easier, and lower-cost methods for genetic testing. Many genetic tests in agriculture, the discipline in which most of the researchers work, are needed in the field, where extended lab analysis can delay their implementation. Likewise for health care, samples for genetic tests are taken in doctors’ offices and clinics that rarely have the equipment needed to prepare specimen samples for analysis.

Botella, Mason, and colleagues therefore investigated simple and inexpensive techniques with readily available materials for their solution. These methods need to reliably capture, isolate, extract, and purify DNA and RNA — nucleic acids carrying instructions from the genetic code in DNA to cells — from plant and animal samples. For capturing samples, the team tested a number of cellulose and nylon materials including household paper towels, and found a type of common filter paper used in labs to give the best and most consistent results.

While the filter paper provided the capture medium, the team also needs a method for reliably acquiring enough genetic material in the sample for analysis. The plant tissue or fluid sample is placed in a tube with reagents and ball bearings that help soften tissue samples. The team made a dipstick by fixing a small piece of filter paper, about 8 square millimeters, at the end of plastic handle to dip into the tube. The researchers found dipping the filter paper 3 times first into the tube with the sample and reagents, followed by similar 3-times dipping into a wash solution and then an amplification mix, resulted in DNA and RNA samples with sufficient purity for analysis.

The team tested this method with plant leaf tissue infected with fungal and bacterial pathogens, as well as infected animal tissue, and whole human blood, returning results in about 30 seconds. The researchers found their results were comparable to commercial sample preparation techniques using magnetic beads, which take more than 14 minutes. The authors note that commercial sample prep equipment requires upfront costs of $685.00 to $876.00, while their dipsticks can be produced for pennies.

“We have already successfully used dipsticks in remote plantations in Papua New Guinea to diagnose sick trees,” says Botella in a university statement, “and have applied it to livestock diseases, diseases in human samples, human pathogens in food, and in detecting environmental risks such as E. coli-contaminated water.” Botella adds, “By combining our dipsticks with other newly developed technologies by our group, the entire diagnostic process from sample collection to final result can be easily performed in a hospital, farm, hotel room, or even a tropical jungle.”

The university’s technology transfer office filed a patent for the technology, and is seeking commercial partners to take it to market.

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