Correlated Optical and Isotopic Nanoscopy

August 22, 2014

The isotopic composition of different materials can be imaged by secondary ion mass spectrometry. In biology, this method is mainly used to study cellular metabolism and turnover, by pulsing the cells with marker molecules such as amino acids labelled with stable isotopes (15N, 13C). The incorporation of the markers is then imaged with a lateral resolution that can surpass 100 nm. However, secondary ion mass spectrometry cannot identify specific subcellular structures like organelles, and needs to be correlated with a second technique, such as fluorescence imaging. Here, we present a method based on stimulated emission depletion microscopy that provides correlated optical and isotopic nanoscopy (COIN) images. We use this approach to study the protein turnover in different organelles from cultured hippocampal neurons. Correlated optical and isotopic nanoscopy can be applied to a variety of biological samples, and should therefore enable the investigation of the isotopic composition of many organelles and subcellular structures.

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Saka SK, Vogts A, Kröhnert K, Hillion F, Rizzoli SO, and Wessels JT:
Correlated Optical and Isotopic Nanoscopy

Nature Communications 5: 3664 (2014); doi: 10.1038/ncomms4664

Molecular processes in living cells can best be monitored by high-resolution microscopy techniques. Although groundbreaking technical innovations in the field of microscopy have been made in the past, frontiers still exist. Prof. Dr. Silvio O. Rizzoli and his team of the Göttingen DFG Research Center and Cluster of Excellence for Nanoscale Microscopy and Molecular Physiology of the Brains (CNMPB) have now developed a new application by combining two imaging techniques to expand the benefits of high-resolution to study biological questions. The new imaging technique COIN enables to study the turnover and metabolism of subcellular structures, such as organelles, in detail.

The turnover of subcellular organelles is one of the least understood aspects of modern cell biology, despite its widely recognized importance. In biology, these processes are studied by “feeding” cells with marker molecules such as amino acids labeled with stable isotopes. Over time these amino acids are metabolically incorporated into cellular proteins and the isotopic composition can then be imaged by secondary ion mass spectrometry (SIMS). This technique enables visualization of different organelles in cells and tissues. However, SIMS by itself cannot identify specific subcellular structures.

Therefore, the team of Prof. Rizzoli in collaboration with scientists of the Leibniz Institute for Baltic Sea Research in Warnemünde and the French company Cameca successfully correlated SIMS with a second technique. The combined method termed “correlated optical and isotopic nanoscopy (COIN)” is based on super-resolution stimulated emission depletion (STED) microscopy. COIN allows precise studies of the protein turnover in different single organelles from cultured hippocampal neurons.

Each of the combined techniques alone provides a piece of information that is unavailable for the other: “SIMS yields the isotopic composition of the material investigated and even its turnover, while STED microscopy reveals the identities and the spatial distribution of organelles or organelle components.”, Prof. Rizzoli explains.

The combination (COIN) for the first time allows precisely determining the turnover of proteins in various single organelles in cells. A special feature of the technique is the wide-range application to a variety of biological  samples, which should therefore enable the investigation of the composition of many organelles and sub-cellular structures. Using COIN the scientists successfully yielded information about the protein turnover in different organelles of cultured hippocampal neurons. COIN can be applied to a variety of biological samples, and should therefore enable the investigation of the isotopic composition of many organelles and subcellular structures.

From left to right: Dr. Johannes Wessels, Dr. Sinem, K. Saka, Katharina Kröhnert, Prof. Dr. Silvio O. Rizzoli.

More information:
CNMPB: http://www.cnmpb.de

Prof. Dr. Silvio O. Rizzoli
University Medical Center Göttingen
Department Neuro- & Sensory Physiology
c/o European Neuroscience Institute (ENI)
Grisebachstraße 5, 37077 Göttingen
Phone +49 (0) 551 / 39-33630
srizzol@gwdg.de

CNMPB – Center for Nanoscale Microscopy and Molecular Physiology of the Brain
Cluster of Excellence 171 – DFG Research Center 103
Dr. Heike Conrad
Scientific Coordination, Press & Public Relations
Humboldtallee 23, 37073 Göttingen
Phone +49 (0) 551 / 39-7065
heike.conrad@med.uni-goettingen.de

Leibniz-Institut für Ostseeforschung Warnemünde
Sektion Biologische Meereskunde
Dr. Angela Vogts
Phone +49 (0) 381 / 5197 353
angela.vogts@io-warnemuende.de

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