The MIT Technology Review features an article on current work by Complete Genomics out of Mountain View, CA and BioNanomatrix of Philadelphia, that try to develop a method to sequence the human genome for about $100, a serious drop from the current cheapest $60,000 method.
Most existing technologies detect the sequence of DNA a single letter at a time. But Complete Genomics aims to speed the process by detecting entire “words,” each composed of five DNA letters. Drmanac likens the technology to Google searches, which query a database of text with keywords. Further speeding up the process with novel chemistry and advances in nanofabrication, the companies will develop a device that can simultaneously read the sequence of multiple genomes on a single chip.
To accomplish the new sequencing, scientists first generate all possible combinations of five-letter DNA segments, given the four letters, or bases, that make up all DNA. These segments are labeled with different types of fluorescent markers and added in groups to a single-stranded molecule of DNA. When a particular segment matches a sequence on the strand of DNA to be read, it binds to that part of the molecule. A specialized camera then snaps a picture–the different fluorescent signals indicate the sequence at specific points along the strand of DNA. The process is repeated with different five-letter DNA combinations, until the entire chromosome is sequenced. The approach is feasible because of the recent availability of cheap DNA synthesis, making it much more efficient to generate libraries of these DNA segments.
Each DNA molecule will be threaded into a nanofluidics device, made by Philadelphia-based BioNanomatrix, lined with rows of tiny channels. The narrow width of the channels–about 100 nanometers–forces the normally tangled DNA to unwind, lining up like a train in a long tunnel and giving researchers a clear view of the molecule. “Since we can stretch out DNA, we can get a huge amount of information from each piece of DNA we look at,” says Mike Boyce-Jacino, chief executive officer of BioNanomatrix. “The big difference from any other approach is that we are looking at physical location at the same time we are looking at sequence information.” Sequencing methods currently in use sequence small fragments of DNA and then piece together the location of each fragment computationally, which is more time consuming and requires repetitive sequencing.
Full post at MIT Tech Review…
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