This news release is available in Japanese.
Researchers have significantly extended the resolution of live-cell Structured Illumination Microscopy (SIM), a type of microscopy that offers many benefits compared to other super resolution techniques. The results are already providing a much more detailed understanding of cell processes and could have important implications for health research. Currently, many other super resolution microscopes come with pitfalls; for example, localization microscopy and stimulated emission depletion microscopy must use high levels of illumination intensity and fluorescent markers in order to acquire images, which can damage live cells, even after short periods of time. SIM uses much lower levels of illumination intensity, but to date its resolution has been limited to twice the diffraction limit. To improve the resolution of SIM, Dong Li et al. used a higher numerical aperture (NA) lens. Higher NA not only improved the resolution of SIM from 100 nanometers to 84 nanometers, but restricted the excitation to only a small fraction of the cellular volume, further reducing phototoxicity and eliminating out-of-focus background. In a second approach, the team used stripes of illumination at one wavelength to activate a subset of fluorescent proteins and then induced these to emit fluorescence using a striped pattern at a second wavelength; combined, the two illumination patterns offer 62-nanometer resolution, a much better resolution than could be obtained with only one pattern. Already, the researchers have used these improved resolution techniques to gain new insights into cell processes. For example, scientists debate the role of a protein called actin in clathrin-mediated endocytosis (a process by which cells engulf molecules), but through better resolution in SIM, Li et al. were able to confirm that the presence of actin increases the likelihood that clathrin will help molecules be absorbed by a cell. Their work explores several other cell processes, providing beautiful imagery and exceptional detail of proteins interacting. This paper is accompanied with a multimedia asset that includes interviews with Nobel prize winner Eric Betzig and lead author Dong Li, explaining their work and its applications.
Article #6: "Extended-resolution structured illumination imaging of endocytic and cytoskeletal dynamics," by D. Li; L. Shao; B.-C. Chen; E. Betzig at Howard Hughes Medical Institute in Ashburn, VA; X. Zhang; M. Zhang; P. Xu at Chinese Academy of Sciences in Beijing, China; X. Zhang at Central China Normal University in Wuhan, China; B. Moses; D.E. Milkie at Coleman Technologies in Newtown Square, PA; J.R. Beach; J.A. Hammer III; M.A. Baird at National Heart, Lung, and Blood Institute, National Institutes of Health in Bethesda, MD; M. Pasham; T. Kirchhausen at Harvard Medical School in Boston, MA; M. Pasham; T. Kirchhausen at Boston Children's Hospital in Boston, MA; M.A. Baird; M.W. Davidson at Florida State University in Tallahassee, FL; B.-C. Chen at Academia Sinica in Taipei, Taiwan.