Researchers succeed in knotting DNA molecule

A group of Japanese researchers have succeeded in knotting a single DNA molecule, an operation they say is the first in the world. The scientists attached beads to both ends 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 photo was provided by a Keio University research group that took part in the experiment.