06 May 1994
Vol 264, Issue 5160

About The Cover

Images of tube-like motion of a single DNA molecule. A fluorescently stained DNA molecule (60 micrometers long) was attached to a 1-micrometer polystyrene sphere (red) and moved through a background of concentrated, unstained Λ-DNA. The DNA was stretched out in the shape of an ``R'' by the use of joystick-controlled optical tweezers. The resulting tube-like motion is directly visualized in this series of pseudocolored images spaced every 8.3 seconds. See pages 819 and 822. [Digital image: Thomas T. Perkins]