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Cell’s secrets coming to light –

Microscopy in 3D, multicolor and ultra high resolution

Munich, 06/05/2008

Light microscopy is a key technology in modern cell biology and allows – especially in combination with fluorescent dyes – the specific localization of nearly all cellular components. A fundamental limitation, though, of all these techniques is the low resolution of optical microscopy relative to the scale of subcellular structures. An international research team under the lead of Professor Heinrich Leonhardt at Ludwig-Maximilians-Universität (LMU) München and Professor John W. Sedat at the University of California in San Francisco, have now found a way to circumvent this so-called Abbe limit. As reported online in the “Science” journal they applied three-dimensional structured illumination microscopy or 3D-SIM to study the nucleus of a mammalian cell – and detected several features that escape detection by conventional microscopy. “Some details have been seen previously only by electron microscopy,” says Leonhardt. “Multicolor 3D-SIM therefore opens new and facile possibilities for all fields of life sciences, from basic to biomedical research. This new technique allows to reconstruct a three dimensional image with an ultra high resolution below the Abbe limit. We expect that commercial models will be available within a year.”

The limitations to spatial resolution in light microscopy has been discovered – and named after – the German physicist Ernst Abbe in the 19th century. The so-called Abbe limit depends on the wavelength of light and makes it hard to achieve a resolution below 200 nanometer which equals 200 billionths of a meter. “Our trick was to use a structured illumination to cause what researchers usually try to avoid: an interference visible as a shadow pattern across the image,” says Leonhardt. “But since we knew the fine pattern of light we used for illumination, we could then calculate with some mathematics and a good computer the unknown details of the biological specimen.”

And they got some surprising details: The research team tested their novel approach with the nucleus of a mammalian cell. The result was a three dimensional image with doubly the resolution of conventional light microscopes. “It was – in my opinion – a fascinating and unprecedented view of a dividing cell shortly before the birth of two daughter cells”, recalls Leonhardt. “This is one of the most fundamental processes of life and therefore intensively studied by research groups, also because errors may cause cell death or, even worse, give rise to a tumor.”

The image shows a nucleus preparing for cell division. The genetic material is condensed into chromosomes which are clearly visible under the nuclear membranes – and with even some new details on their surface. Different layers of the nuclear envelope can be distinguished and two invaginations have appeared: “They are caused by structures called centrosomes which will shortly begin to pull the nuclear envelope apart,” explains Leonhardt. “The centrosomes will then pull the condensed chromosomes – one of a couple each – to their sides and thus distribute identical copies of the genetic material to the newborn daughter cells.”

The new technique even allows pictures and movies in 3D. In the future, it might be possible to capture whole processes on film as well. At the moment, 3D-SIM is the only imaging technique that can produce multicolour 3D images of whole cells with enhancement of resolution. “It is important for researchers to note that these results were obtained with standard methods to prepare and dye the cells and their structures,” stresses Leonhardt. “Also, the 3D-SIM microscope platform is not more difficult to use than conventional commercial microscopes.

The study was conducted on a prototype based on conventional microscope technology but commercial models should become available within a year. The possibility of using 3D-SIM with well-established standard labelling techniques and to simultaneously locate different molecules or structures in the three dimensional context and in multicolour will undoubtedly open interesting new perspectives for molecular cell biology and biomedical research alike.


“Subdiffraction Multicolor Imaging of the Nuclear Periphery with 3D Structured Illumination Microscopy”,
Lothar Schermelleh, Peter M. Carlton, Sebastian Haase, Lin Shao, Lukman Winoto, Peter Kner, Brian Burke, M. Cristina Cardoso, David A. Agard, Mats G. L. Gustafsson, Heinrich Leonhardt, John W. Sedat,
Science, online on June 6, 2008


Professor Dr. Heinrich Leonhardt
BioCenter at  LMU Munich
Department of Biology
Tel.: + 49-89 / 2180 – 74232


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