Two developments, expanding the potential applications of high-resolution fluorescence imaging, are published online by Nature Methods. Both expand the potential applications of ultrahigh-resolution fluorescence imaging, making it more widely accessible.
The resolution of fluorescence microscopy is generally limited because of diffraction. Motivated by a need to increase resolution, and permit scientists to better visualize biological details in cells, much like the Hubble telescope allows astronomers to see details that are invisible to ground-based telescopes, a handful of scientists are working on developing so called sub-diffraction-limit fluorescence imaging methods, which were previously limited to organic fluorophores, fixed samples and custom-built microscopes.
One pioneer, Stefan Hell demonstrates how one method known as stimulated emission depletion (STED) microscopy can be used in conjunction with fluorescent proteins which are popular for live-cell imaging. This is the first example of sub-diffraction-limit imaging of a fluorescent protein, and it could open the door for high-resolution live-cell imaging in the near future.
A second paper from Xiaowei Zhuang and colleagues, describes a method that allows sub-diffraction-limit fluorescence imaging using a readily available fluorescence microscope system. This method works by actively switching individual fluorophores on and off so that each of their individual positions can be determined precisely in a way that would be impossible using the same imaging system in a conventional way. They demonstrated their method, stochastic optical reconstruction microscopy (STORM), by mapping the locations of proteins bound to a single DNA plasmid.
There is increasing interest in such sub-diffraction-limit imaging techniques as a result of the intense desire to localize and track individual molecules. Such developments are sure to elucidate previously unrecognized biological mechanisms. These two reports highlight the very different methods being pursued to make such studies a reality.
Stefan Hell (Max Planck Institute for Biophysical Chemistry, Göttingen, Germany)
Xiaowei Zhuang (Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA)
Abstracts available online:
Article 1 (Hell) Abstract.
Article 2 (Zhuang) Abstract.
(C) Nature Methods press release.
Message posted by: Trevor M. D'Souza