Number 53 (Story #1), October 29, 1991 by Phillip F. Schewe and Ben Stein GUANINE AND ADENINE HAVE BEEN IMAGED BY STM techniques. A collaboration of scientists at the University of Munich (Germany), the IBM Physics Group in Munich (G. Binnig), and the University of Sheffield (UK) have produced scanning tunneling microscope images showing guanine, one of the four constituent bases in DNA molecules, deposited on two different substrates, graphite and MoS2. The STM pictures reveal isolated guanine molecules lying in ordered two-dimensional (monolayer) islands. The visualization and study of isolated bases, the German scientists believe, may contribute to the goal of sequencing DNA molecules. Meanwhile, a group at Lawrence Livermore National Lab (M.J. Allen et al.) have produced STM images of another DNA base, adenine. (From an article by James Murday of the Naval Research Lab surveying recent STM research, in Physics News in 1991, to be published December 1991.)