Eric Betzig of HHMI’s Janelia Research Campus is one of the recipients of the 2014 Nobel Prize in Chemistry for his role in the development of a microscopy technique for visualizing molecules with a precision of 2–25 nm. This ”super-resolution” technique achieves 10 to 100 times higher resolution than previously achieved with a light microscope. This image shows a single E. coli bacterium. E. coli can detect and move toward higher concentrations of amino acids, a source of food, using sensor molecules on the bacterium’s outer membrane—a process called chemotaxis. The blue and red dots mark the locations of sensor proteins that detect the amino acid aspartate. The two colors indicate the locations of the proteins in three-dimensional space: the red ones are closer to the microscope (i.e., top of the bacterium) and the blue ones further away. The length of the bacterium is about 3 µm.
The image was taken from Greenfield et al. (2009) Self-Organization of the Escherichia coli Chemotaxis Network Imaged with Super-Resolution Light Microscopy, published in PLOS Biology 7(6): e1000137. doi:10.1371/journal.pbio.1000137
Link to Licence: http://creativecommons.org/licenses/by/4.0/legalcode
The image was cropped from figure S6A, and the 1µm scale bar and the letter “A” was digitally removed from the figure.
The image was generated using a technique developed by Eric Betzig and others called photoactivated localization microscopy, or PALM. In PALM, fluorescent molecules are attached to proteins of interest, and stimulated to emit light by a laser beam in the microscope. The position of the emitted light is recorded and the process is repeated multiple times. By mathematically analyzing the result of many such stimulations, the average position of the protein can be ascertained at a precision of 15 nanometers. This far exceeds the limit of conventional light microscopy.
HHMI News: Eric Betzig wins 2014 Nobel Prize in Chemistry