A new light microscope so powerful that it allows scientists peering inside cells to discern the precise location of nearly each individual protein they are studying has been developed and successfully demonstrated by scientists at the Howard Hughes Medical Institute's Janelia Farm Research Campus in collaboration with researchers at the National Institutes of Health and Florida State University.
The new technique far surpasses the resolution of conventional optical microscopes, which are inherently limited by the wavelength of light. With these microscopes, objects separated by less than 200 nanometers cannot be distinguished from one another. While researchers can learn a lot by studying the arrangement of proteins inside cells at this resolution, it is insufficient to pinpoint the location of individual proteins – which are typically only one to two nanometers in diameter. The new approach, called photoactivated localization microscopy (PALM), brings scientists far closer to this goal – discriminating molecules that are only two to 25 nanometers apart.
The scientists published the details of the new technique in the August 10, 2006, edition of Science Express, an advance online publication of the journal Science.