Thaindian News

Washington, July 28 (ANI): Human genome sequencing is expected to become as cheap as 100 dollars per case, and that too at speeds 20,000 times faster than second-generation sequencers currently on the market, with a new device being developed to watch DNA being copied in real time.

Stephen Turner, the Chief Technology Officer at Pacific Biosciences, has revealed Single Molecule Real-Time (SMRT) sequencing will be released commercially in 2010.

A decade ago, it took Celera Genomics and the Human Genome Project years to sequence complete human genomes.

In 2008, James Watson’s entire genetic code was read by a new generation of technology in months.

With SMRT sequencing, Pacific Biosciences experts expect to accomplish the same feat in minutes.

The method used in the Human Genome Project taps into the cell’s natural machinery for replicating DNA.

The enzyme DNA polymerase is used to copy strands of DNA, creating billions of fragments of varying length. Each fragment ends with a tiny fluorescent molecule that identifies only the last nucleotide in the chain, and by lining these fragments up according to length, their glowing tips can be read off like letters on a page.

Instead of inspecting DNA copies after polymerase has done its work, SMRT sequencing watches the enzyme in real time as it races along and copies an individual strand stuck to the bottom of a tiny well.

Every nucleotide used to make the copy is attached to its own fluorescent molecule that lights up when the nucleotide is incorporated, and this light is spotted by a detector that identifies the colour and the nucleotide - A, C, G, or T.

The researchers behind this technology hope that repeating this process simultaneously in many wells may help bring about a substantial boost in sequencing speed.

“When we reach a million separate molecules that we’re able to sequence at once … we’ll be able to sequence the entire human genome in less than 15 minutes,” said Turner.

The device also has the potential to reduce the number of errors made in DNA sequencing. Given that the errors made by SMRT sequencing are random, that is not systematically occurring at the same spot, they are more likely to disappear as the procedure is repeated.

A presentation on “Single Molecule Real-Time DNA Sequencers” was made at the 2009 Industrial Physics Forum, a component of the 51st Annual Meeting of American Association of Physicists in Medicine, on Monday. (ANI)