A new microscope developed by scientists at the European Molecular Biology Laboratory (EMBL; Heidelberg, Germany) combines light-sheet microscopy and single molecule spectroscopy, allowing researchers to view rapid molecular movement in living cells.
Combining the two techniques allows the microscope to record the fluorescence of every pixel within view and take snapshots at <1 ms intervals. The new microscope enables scientists to view and measure fast processes—including the way molecules diffuse—across a whole sample, even one containing several cells. Previous techniques based on confocal microscopy enabled researchers to only observe at most a few isolated spots in a sample at a time.
Published online in Nature Biotechnology, the new microscope allows researchers to follow fluorescently tagged molecules in whole live cells, in 3-D, and see how their biochemical properties, like interaction rates and binding affinities, vary throughout the cell, says Malte Wachsmuth, who developed the microscope at EMBL.
Chromatin—the combination of DNA, RNA and proteins that forms chromosomes—had been observed wound tightly together, with most of its DNA inaccessible to the cell’s gene-reading machinery (heterochromatin), and loosely packed and easily readable (euchromatin). But when they used the new microscope to measure the interaction between chromatin and a protein called HP1-α, the EMBL scientists discovered that in the areas that look like euchromatin, HP1-α behaves as it would in the presence of heterochromatin, says Michael Knop, now at the University of Heidelberg, Germany. “This suggests that chromatin may also exist in an intermediate state between hetero- and euchromatin, which was not observable before in living cells,” he says.
The EMBL scientists believe their new microscope will help to investigate processes ranging from the role of growth hormones in cancer to the regulation of cell division and signaling and the patterning of tissue development in the embryo.
Posted by Lee Mather
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