Continuous and simultaneous excitation and detection. Both excitation and detection occur without interruption through the transparent glass bottom of the SMRT™ chip.
Pacific Biosciences has a Single Molecule Real-Time (SMRT) DNA sequencing, due to be released commercially in 2010 and could enable $100 genome sequencing in 15 minutes in 2013. The second generation real time DNA reader in 2013 is the one that is expected to hit the $100 genome sequencing price. They will release a product in 2010 but it will not be that cheap.
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. This light is spotted by a detector that identifies the color and the nucleotide -- A, C, G, or T.
By repeating this process simultaneously in many wells, the technology hopes to 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 speed of the reaction is currently limited by the ability of the detector to keep up with the polymerase. The first commercial instrument will operate at three to five bases per second, and Turner reports that lab tests have achieved 10 bases per second. The polymerase has the potential to go much faster, up to hundreds of bases per second. "To push past 50 bases per second, we will need brighter fluorescent reporters or more sensitive detection," says Turner.
The device also has the potential to reduce the number of errors made in DNA sequencing. Current technologies achieve an accuracy of 99.9999 percent (three thousand errors in a genome of three billion base pairs). "For cancer, you need to be able to spot a single mutation in the genome," said Turner. Because the errors made by SMRT sequencing are random -- not systematically occurring at the same spot -- they are more likely to disappear as the procedure is repeated.
Recently three people (a Stanford professor and two assistants) sequenced a genome for $50,000.
Helicos Biosciences Corp.’s gene- sequencing machine mapped the genome of a Stanford University professor, who developed the technology, for less than $50,000 using the labor of just three people, researchers reported.
Illumina also has cheap DNA sequencing. Offering to sequence a genome for $48,000
14 page pdf background info on Pacific Biosciences real time DNA reading technology