Making machines from genes.

It's been a while since DNA just encoded genes. During the past decade, scientists have found ways to use this celebrity of molecular biology as an electrical wire (SN: 7/13/96, p. 26), a girder for making elaborate structures, and a computing device. (SN: 8/14/99, p. 104) (SN: 9/18/99, p. 181).

In a new twist for the helical molecule, DNA takes on a role of power. It's the fuel for a device made of--guess what!--DNA.

DNA molecules are long chains of smaller molecules, called bases, designated by A, C, G, and T. Because Ts tend to bond with As, and Cs with Gs, a single strand of DNA will join, or hybridize, with a strand that has its complementary series of bases.

To explore what kinds of machinery can be made with DNA, Bernard Yurke of Bell Laboratories' Lucent Technologies in Murray Hill, N.J., and his colleagues have fashioned three DNA strands into a tweezers.

The researchers report that they can make their DNA tweezers squeeze just by adding a piece of "fuel" DNA. When they add what they call a "removal" strand, which is complementary to the fuel DNA, the tweezers opens again. The fuel, now hybridized to its mate, drifts away.

To clarify the fuel analogy, Yurke notes that the machine is "using the energy that's effectively made available by the hybridization of the fuel and removal strands." The researchers describe their invention in the Aug. 10 NATURE.