Now, a machine that sequences single molecules of DNA

April 7th, 2008 - 3:22 pm ICT by admin  

London, April 7 (ANI): Massachusetts-based company Helicos BioSciences has developed a machine that can sequence single molecules of DNA and, thereby, reduce the time and cost of sequencing an individuals genome.

The effectiveness of the single-molecule DNA sequencers lies in the fact that they do not require the DNA to be amplifiedi.e. copied into multiple, identical strandsbefore it is sequenced.

The amplification step can introduce errors into the sequence and does not work well for some DNA fragments, making it difficult to sequence a genomes full complement of DNA.

They’re cool. Eventually, single-molecule sequencing will be what we use, Nature magazine quoted Edward Rubin, director of the US Department of Energys Joint Genome Institutea genome-sequencing facility in Californiaas saying.

Helicos technique is based on a method called sequencing by synthesis, which begins by chopping the genome into small fragments.

An enzyme then attaches a short DNA tag onto the end of each fragment. The tag binds to a complementary DNA molecule attached to a platform, anchoring the DNA fragment in place.

A DNA replicating enzyme is then added along with a stock of DNA ‘letters’ or bases carrying fluorescent labels. As the fluorescent DNA forms into strands that complement the genome fragments, a camera takes a picture of each newly added base.

So far, Helicos has used its machine to sequence the genome of a virus called M13 that infects bacteria, which is nearly a millionth the size of the human genome.

Experts at the firm reckon that their machine may be ready to sequence a human genome for about 72,000 dollars in eight weeks.

The firms official web site says that the machine itself will cost customers about 1.35 million dollars. (ANI)

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