Just saw this article in Genomeweb
250 kilobases is really amazing! The limit is 500 Kbases though.
as a product if they can do it cheaply, it's a godsend for de novo transcriptomics. (but it might be an overkill now that I see what it can do)
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Primed DNA templates tethered to a slide are illuminated with a 405-nanometer laser, and as polymerases synthesize DNA at a rate of between two and 10 nucleotides per second, signals are recorded inside the evanescent field of a total internal reflection fluorescence microscope.
Life Tech's technology faces the same challenge as Pacific Biosciences' in that the laser inactivates the polymerase after a certain time — in Life Tech's case after synthesizing about a kilobase of DNA. But unlike PacBio, Life Tech does not immobilize the polymerase, so it can wash off "dead" enzyme and replace it with a new batch of polymerase that picks up where the old one left off..... Beechem, who said he was not at liberty to discuss how the DNA is made to lie down on the slide, showed that this "top-down" sequencing approach has allowed him and his colleagues to analyze DNA as long as 250 kilobases with about 30 polymerases generating sequence information at the same time. The result is a large number of paired-end reads on the same DNA molecule.....
He stressed, however, that the method is currently not close to becoming a product.
While the size limit is currently about 500 kilobases of DNA, the ultimate goal, he said, is to analyze entire chromosomes this way. Researchers could, for example, study DNA from a tumor and its normal control at the same time, or focus in on specific regions of a chromosome....
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