Combined X-ray and fluorescence microscope reveals unseen molecular details

October 17, 2018, Helmholtz Association of German Research Centres
STED image (left) and X-ray imaging (right) of the same cardiac tissue cell from a rat. For STED, the network of actin filaments in the cell, which is important for the cell’s mechanical properties, have been labeled with a fluorescent dye. Contrast in the X-ray image, on the other hand, is directly related to the total electron density, with contributions of labeled and unlabeled molecules. By having both contrasts at hand, the structure of the cell can be imaged in a more complete manner, with the two imaging modalities “informing each other”. Credit: University of Göttingen, M. Bernhardt et al.

A research team from the University of Göttingen has commissioned a worldwide unique microscope combination at DESY's X-ray source PETRA III to gain novel insights into biological cells. The team led by Tim Salditt and Sarah Köster describes the combined X-ray and optical fluorescence microscope in the journal Nature Communications. To test the performance of the device installed at DESY's measuring station P10, the scientists investigated heart muscle cells with their new method.

Modern light microscopy provides with ever sharper images important new insights into the interior processes of , but highest resolution is obtained only for the fraction of biomolecules which emit fluorescence light. For this purpose, small have to be first attached to the molecules of interest, for example proteins or DNA. The controlled switching of the fluorescent dye in the so-called STED (stimulated emission depletion) then enables highest resolution down to a few billionth of a meter, according to principle of optical switching between on- and off-state introduced by Nobel prize winner Stefan Hell from Göttingen.

"But how can we get sharp images of all , including those molecules to which fluorescent markers cannot be attached," asks Salditt. "How can we illuminate the 'dark background' of all unlabelled molecules, in which the specifically labelled fluorescent biomolecules are embedded?"

Salditt's and Köster's team has now combined a STED- and an X-ray microscope, which can quasi simultaneously map fluorescence and the density distribution of the total of cellular components in the cell. "In addition, X-ray diffraction experiments, which are well known from crystallography, can also be carried out at precisely controlled positions in the cell," explains co-author Michael Sprung, head of the measuring station P10 where the new device has been installed.

"With this novel X-ray/STED microscope we have visualised a network of protein filaments in in STED mode first. The were then also imaged by X-ray holography to cover the spatial distribution of mass density in the entire cell, including all of its components," explains Marten Bernhardt, lead author of the article. "By using complementary contrast we aim at a more complete understanding of the structure underlying contractibility and force generation in the cells," adds Salditt. "In future, we want to apply this also to observe dynamic processes in living cells," explains Köster, spokesperson of the collaborative research centre Collective behaviour of soft and biologcal matter of the German Science Foundation (DFG), which provides the research framework of the experiments.

Explore further: Background suppression for super-resolution light microscopy

More information: M. Bernhardt et al. Correlative microscopy approach for biology using X-ray holography, X-ray scanning diffraction and STED microscopy, Nature Communications (2018). DOI: 10.1038/s41467-018-05885-z

Related Stories

Background suppression for super-resolution light microscopy

February 1, 2017

Researchers of Karlsruhe Institute of Technology (KIT) have developed a new fluorescence microscopy method: STEDD (Stimulation Emission Double Depletion) nanoscopy produces images of highest resolution with suppressed background. ...

Scientists created proteins controlled by light

October 1, 2018

Researchers have developed fluorescent proteins that can be controlled by orange and green light. These proteins will help to study processes in living cells. Results were published in Nature Methods.

More Details in the Nanocosmos of the Cell

August 18, 2006

Scientists at the Max Planck Institute for Biophysical Chemistry have further opened the door to the nanocosmos of the cell. The researchers have, for the first time, improved the resolution of STED microscopes (Stimulated ...

Watching molecule movements in live cells

July 24, 2013

The newly developed STED-RICS microscopy method records rapid movements of molecules in live samples. By combining raster image correlation spectroscopy (RICS) with STED fluorescence microscopy, researchers of Karlsruhe Institute ...

Recommended for you

Scientists bring polymers into atomic-scale focus

November 12, 2018

From water bottles and food containers to toys and tubing, many modern materials are made of plastics. And while we produce about 110 million tons per year of synthetic polymers like polyethylene and polypropylene worldwide ...

Synthetic molecule invades double-stranded DNA

November 12, 2018

Carnegie Mellon University researchers have developed a synthetic molecule that can recognize and bind to double-stranded DNA or RNA under normal physiological conditions. The molecule could provide a new platform for developing ...

Nitrogen fixation in ambient conditions

November 12, 2018

Abundant in the atmosphere, nitrogen is rarely used in the industrial production of chemicals. The most important process using nitrogen is the synthesis of ammonia used for the preparation of agricultural fertilizers.

New catalyst turns pollutant into fuel

November 12, 2018

Rather than allow power plants and industry to toss carbon dioxide into the atmosphere, incoming Rice University assistant professor Haotian Wang has a plan to convert the greenhouse gas into useful products in a green way.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.