Correlating light and electron microscopy

When Eric Betzig and colleagues first described their new microscopy method, PALM, they chose to highlight its power by comparing it to an ultra-high-resolution approach: transmission electron microscopy (TEM). PALM, or photoactivated localization microscopy, is a super-resolution fluorescence technique allowing users to circumvent the 200 nm diffraction limit that constrains optical microscopy, mapping fluorophores to within 10 nm or so. It produces exceptionally sharp images of the distribution of specific molecules in a cell. The only problem is that the resulting signals are nothing more than bright dots on a black background—“little blobs floating in darkness,” as Harald Hess, a colleague of Betzig at Howard Hughes Medical Institute’s Janelia Farm Research Campus and co-author with Betzig on the first PALM article, describes it. Hess, Betzig and their colleagues were stuck with a question: where exactly in the cell were those blobs located? … Read more at


~ by jeffreyperkel on October 14, 2014.

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