Researchers use new microscope to ’see’ atoms for first time

UCLA researchers report in the April 30 edition of the journal Cell that they have imaged a virus structure at a resolution high enough to effectively "see" atoms, the first published instance of imaging biological complexes at such a resolution. The research team, led by Hong Zhou, UCLA professor of microbiology, immunology and molecular genetics, used cryo-electron microscopy to image the structure at 3.3 angstroms. An angstrom is the smallest recognized division of a chemical element and is about the distance between the two hydrogen atoms in a water molecule. The study, the researchers say, demonstrates the great potential of cryo-electron microscopy, or Cryo-EM, for producing extremely high-resolution images of biological samples in their native environment. "This is the first study to determine an atomic resolution structure through Cryo-EM alone," said Xing Zhang, a postdoctoral candidate in Zhou's group and lead author of the Cell paper. "By proving the effectiveness of this microscopy technique, we have opened the door to a wide variety of biological studies." With traditional light microscopy, a magnified image of a sample is viewed through a lens. Some samples, however, are too small to diffract visible light (in the 500 to 800 nm range, or 5,000 to 8,000 angstroms) and therefore cannot be seen.