Innovative Imaging Technique Reveals New Cellular Secrets

Key parts of mitosis rely on tiny, tube-shaped structures, called spindle pole bodies (SPBs). Until now, the nanoscale process of SPB duplication has remained elusive to researchers, largely due to the resolution limits of current optical microscopy. A common alternative, electron microscopes, can see much smaller objects, but do not work on living cells.

Now, a team of researchers from the Stowers Institute for Medical Research and the University of Colorado Boulder has devised a novel optical technique — a combination of structured illumination microscopy (SIM) and single-particle averaging (SPA) — to resolve individual components of SPB duplication in living yeast cells. SIM makes laser-based interference patterns that change based on what they interact with, doubling the resolution of optical microscopes, while SPA brings tiny objects and their locations into sharper focus by averaging many images into one “typical” picture. Using this method, the team was able to achieve a precision within a 10-30 nm range. Visualizing the SPB duplication using the SIM-SPA technique, the researchers were able to determine that these structures form at different times than previously thought. They also spotted a number of never-before-seen structures used in SPB duplication.

Associate Investigator Sue Jaspersen, PhD, who led the study, credits the collaboration between her lab and members of the Institute’s scientific support groups for developing this technique. “I told them what I wanted to investigate and they made it happen,” Jaspersen says. “At the cutting edge of resolution, every little part matters. Research Specialist Zulin Yu, PhD, of the Microscopy Facility made sure we took the best images and Research Advisor Jay Unruh, PhD, helped us analyze them in fantastic new ways.” According to Jaspersen, the SPA-SIM technique is applicable to a wide variety of subjects beyond SPB structure and has opened up new possibilities in the field of cellular imaging.

These insights were published online September 15, 2015, by eLife.