Researchers succeed in knotting DNA molecule

Gina Miller (
Thu, 3 Jun 1999 13:59:59 -0700

Researchers succeed in knotting DNA molecule Kyodo News Service/Associated Press

TOKYO, June 3 (Kyodo) -- A group of Japanese researchers have succeeded in knotting a single DNA molecule for the first time ever, according to Thursday's issue of a British scientific weekly.

The report, published in Nature magazine, describes how the scientists attached a bead to either end of a molecule of DNA in lambda phage, a cell-destroying virus found in coli bacillus, and used optical tweezers to maneuver the beads to tie a knot.

The task of tying the knot is said to take only "tens of seconds."

They used the same microscopic procedure to tie a knot with a filament of rabbit skeletal actin, a cellular protein that contributes to muscular contraction and cellular movement.

Comparing the two knots, the researchers found that the DNA molecule's knot was more flexible because the actin broke at the knot when bent using a force of one-10 billionth of a gram, while the DNA knot did not break when bent with a force 20 times as great.

"The DNA is tough so we expect it can be used as a thread in microscopic
surgery involving tying together cells and nerves," said a member of the research project headed by Yasuharu Arai, a former graduate student at Keio University.

The DNA (deoxyribonucleic acid) is a two-chained nucleic acid which plays a central role in the storage and replication of hereditary information and in the expression of this information through combinations with protein.

The research was a joint effort by Keio's Department of Physics, the genetic programming team at Core Research for Evolutional Science and Technology, and the Tsukuba Research Laboratory.

Gina "Nanogirl" Miller
Nanotechnology Industries
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"Nanotechnology: solutions for the future."