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Tools and Equipment of Science

Author(s): Roberta Anding, MS, RD/LD, CDE
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Pyrosequencing (454 Life Sciences)

Edited Transcript from “The Pathway to Genomic Medicine,” Richard Gibbs, PhD*
The other option that’s really out there is the 454 machine, which uses a slightly different approach. Individual DNA molecules are captured on a bead, a very small bead, and then amplified around that bead in a test tube filled with oil and water. Little aqueous bubbles covered in oil form a little reaction chamber and allow that one molecule to amplify around that one bead. So you take your DNA, shear it, put it in a tube,  extract the beads, and then put them into a flat chip that is actually 1.3 million wells with little etchings on it—it’s glass fibers fused, shaved, polished, and etched; it’s quite extraordinary. So those big beads in the bottom there are actually the beads with the DNA. The little beads are just packing beads. So that thing is pushed up against a camera, and the chemistry is done and you get to produce the DNA sequence. You get maybe 100 million bases per run. Those old machines from Applied Biosystems, 100,000 bases. So you see the growth in the technology.

* Notes in this slide presentation are adapted from the transcript of “The Pathway to Genomic Medicine,” a presentation by Richard Gibbs, PhD, given in August 2007, as part of Baylor College of Medicine’s Department of Medicine Grand Rounds Human Genetics Symposium.