Winner of Nobel Prize in Chemistry is long-term user of Swiss Light Source at the Paul Scherrer Institute

The Paul Scherrer Institute congratulates Professor Venkatraman Ramakrishnan on the Nobel Prize in Chemistry. Ramakrishnan is a long-term user of the Swiss Light Source SLS at the Paul Scherrer Institut in Switzerland. He used this facility for his prize winning studies on the structure of the ribosome.

Venkatraman Ramakrishnan from the MRC Laboratory of Molecular Biology in Cambridge, UK, shares the prize with Thomas A. Steitz, Yale University, New Haven, USA, and Ada E. Yonath, Weizmann Institute of Science, Rehovot, Israel for research into the structure and function of the ribosome, a large complex molecule which can be seen as the factory for the production of proteins, the latter being the molecular building blocks determining our life processes.

For the determination of the three-dimensional structure of these large molecules, researchers generally employ a technique known as X-ray crystallography: An X-ray beam passes through a crystal composed of the molecules under investigation and a detector placed behind the sample records a characteristic pattern. A detailed analysis of this diffraction pattern allows scientists to determine the positions of the atoms within the molecule. The best diffraction results are generally achieved at so-called third-generation synchrotron radiation sources.

The Swiss Light Source at the Paul Scherrer Institut is one such third-generation source. It operates three advanced protein crystallography beam lines which provide optimal conditions for structure determinations of large bio-molecules such as the ribosome. Unique are the X-ray pixel detectors developed at the Paul Scherrer Institut specifically for this purpose.

X-rays at the Swiss Light Source are generated by electrons travelling almost at the speed of light on a circular trajectory with a circumference of 288 meters. The X-ray radiation produced by such large facilities is much more brilliant than radiation coming out of an ordinary X-ray tube. The SLS is an ‘open access’ facility, i.e. it provides access to users of all nationalities, based on the quality of their research proposals as judged by an international panel. Since 2003 the group of Venkatraman Ramakrishnan has been visiting the SLS for extended measurement campaigns. Experiments at the SLS as well as experiments by this group at other sources resulted in the key publications which led to the Nobel Prize.

The Paul Scherrer Institute develops, builds and operates large and complex research facilities, and makes them available to the national and international scientific community. Its own work concentrates on solid-state research and material sciences, elementary particle physics, biology and medicine, energy research and environmental research. With a staff of 1300 and an annual budget of approximately CHF260 million, this is Switzerland’s largest research institution.

Contacts:
Professor Dr. Friso van der Veen, Paul Scherrer Institut, Department Head Synchrotron Radiation and Nanotechnology, Tel: +41 (0)56 310 5118, +41 (0)79 5936509, e-mail: friso.vanderveen@psi.ch (German, English, Dutch)

Dr. Vincent Olieric, Paul Scherrer Institut, Scientist at the beamline X06SA, Tel: +41 (0)56 310 5233, e-mail: vincent.olieric@psi.ch (French, English)


Publications based on work performed by the group of Venkatraman Ramakrishnan at the SLS which contain results relevant to the Nobel Prize in Chemistry 2009:

Rebecca M Voorhees, Albert Weixlbaumer, David Loakes, Ann C Kelley & V Ramakrishnan;
Insights into substrate stabilization from snapshots of the peptidyl transferase center of the intact 70S ribosome; Nature Structural and Molecular Biology, Volume 16, Issue 5, May 2009, S. 528ff.

Albert Weixlbaumer, Hong Jin, Cajetan Neubauer, Rebecca M. Voorhees, Sabine Petry,
Ann C. Kelley, Venki Ramakrishnan; Insights into Translational Termination from the Structure of RF2 Bound to the Ribosome; Science, Volume 322, 7. November 2008, S. 953ff.

Maria Selmer, Christine M. Dunham, Frank V. Murphy IV, Albert Weixlbaumer, Sabine Petry, Ann C. Kelley, John R. Weir, V. Ramakrishnan; Structure of the 70S Ribosome Complexed with mRNA and tRNA, Science, Volume 313 29. September 2006, S. 1935 ff.

Interior view of the experimental hall at the Swiss Light Source SLS (Photo: H.R. Bramaz/PSI)

Click on picture to enlarge.

Controlling the electronic surface properties of a material

A recent breakthrough by researchers at the Swiss Nanoscience Institute sees for the first time the creation of thin films with controllable electronic properties. This discovery could have a large impact on future applications in sensors and computing. The international collaboration of researchers from the Universities of Basel and Heidelberg and the Paul Scherrer Institute have published the work in the prestigious scientific journal Science.

It's commonly accepted that electrical resistance of a given material cannot be adjusted as is the case with, for example, density and color. However, Dr Meike Stöhr and her collaborators have now succeeded in developing a new method to selectively tune surface properties such as resistance.

The interdisciplinary team of physicists and chemists have developed a substance which, after heating on a copper surface, exhibits a two dimensional network with nanometer sized pores. The interaction of this network with the existing electron gas on the metal surface leads to the following effect: the electrons underneath the network are pushed into the pores to form small bunches of electrons called quantum dots.

Great potential for materials research
By varying parameters such as the height and diameter of the pores the possibility arises to selectively tune the properties of the material. Further possibilities arise from the ability to fill the pores with different molecules. This allows direct access to the properties of the material which are dependent on the electronic structure, such as conductivity, reflectivity and surface catalysis properties. This will lead to the emergence of new materials with adjustable electronic properties.

The underlying physical mechanisms can best be understood by a comparison of the electron-gas with waves in water. Waves on a water surface are reflected by any obstacle they meet. If the obstacle on the surface in question resembles a honeycomb structure, standing waves are set up in each cell of the honeycomb. This then leads to a wave pattern representative of the honeycomb structure of the same size and shape. “Applying this analogy to the electron gas, we see that the interaction of the network structure with the electron gas on the metal surface confines the electrons giving rise to a characteristic electron wave structure of the new material.” says Stöhr.

These pore networks are good candidates for new meta-materials. These are man-made materials which, due to their period architecture, have specific optical and electronic properties not found in nature. These properties can be tuned by changing the properties of their component materials. In the case of pore networks, it is the electronic surface properties which can be tuned by careful selection of the nano-pores.

The University of Basel and the Paul Scherrer Institute are long-term partners of the Swiss Nanoscience Institute (SNI), which is also financed by the Canton of Aargau. The SNI also includes both the Nationaler Forschungsschwerpunkt Nanowissenschaften which was founded in 2001, and the Argovia-Netzwerk, founded in 2006 and also financed by the Canton of Aargau. A key partner in this project was the Swiss Light Source of the Paul Scherrer institute.

Contact:
Dr. Meike Stöhr, Swiss Nanoscience Institute,
Tel. +41 (0) 61 267 37 59, E-Mail: Meike.Stoehr@unibas.ch
Dr. Thomas Jung, Paul Scherrer Institut,
Tel. +41 (0) 56 310 45 18, E-Mail: Thomas.Jung@psi.ch
Dr. Paul Piwnicki, Public Information Officer, Paul Scherrer Institute,
Tel. +41 (0)56 310 29 40, Paul.Piwnicki@psi.ch

Original Publication:
Jorge Lobo-Checa, Manfred Matena, Kathrin Müller, Jan Hugo Dil, Fabian Meier, Lutz H. Gade, Thomas A. Jung, and Meike Stöhr
Band Formation from Coupled Quantum Dots Formed by a Nanoporous Network on a Copper Surface
Science 17 July 2009 [DOI: 10.1126/science.1175141]

Teamwork: Meike Stöhr and Manfred Matena working on the ultrahigh vacuum system at the University of Basel. (Photo: University of Basel)		A two-dimensional “electronic metamaterial” is generated by supramolecular selfassembly on a metal surface. The periodic influence of the porous molecular network on the otherwise free-electron-like surface state results in the formation of an electronic band.

Click on picture to enlarge.

Temperature response in the Altai lags solar forcing
New results from climate research using ice cores from the Siberian Altai

An ice core drilled at the Belukha glacier in the Siberian Altai by a Swiss-Russian research team under the leadership of the Paul Scherrer Institute (PSI) in 2001 has now provided new findings in climate research. Oxygen isotopes in the ice were used to reconstruct the temperatures in the Altai over the past 750 years. The scientists discovered a strong link between regional temperatures and the solar activity in the period 1250-1850, concluding that the sun was an important driver of preindustrial temperature changes in the Altai. The observation that the reconstructed temperatures followed the solar forcing with a delay of 10 to 30 years is particularly interesting. The strong rise in temperature in the Altai between 1850 and 2000 can not be explained by solar activity changes, but rather by the increased concentration of the greenhouse gas CO2 in the atmosphere. The researchers report on these findings in the online edition of the scientific journal Geophysical Research Letters.

The Altai mountains lie on the border between Russia, Kazakhstan, Mongolia, and China, in a region with a particularly pronounced continental climate. In 2001, an international research team under the leadership of Margit Schwikowski (Paul Scherrer Institute) drilled a 139 m-long ice core at the Belukha glacier, near the highest mountain of the Altai. Following extensive work in the laboratory, this core has now revealed its secrets.

Ice core acting as a thermometer
The ice core was cut into 3600 samples at -20°C in the PSI’s cold room, and the 16O and 18O oxygen isotope content determined with an isotope mass spectrometer. It was demonstrated that the behaviour of the stable oxygen isotope ratio has closely followed the record of the temperature measured at a nearby weather station over the past 130 years. This parameter can therefore be used as a measure for temperature in the past. The deepest sample was dated to the year 1250, which means that the ice core contains climate information covering the past 750 years.

Solar activity influences temperature
The total solar irradiance is not a constant factor. It fluctuates periodically around a value of 1365 watts per square metre. The best-known cycle has an average duration of 11 years. It has only been possible to measure solar activity directly since 1978, but the number of sun spots – a measure of solar activity – has been observed through telescopes from as far back as the year 1610. Information about the solar activity before that time can be provided by other indirect methods: analysis of the cosmogenic radio-nuclides 10Be from polar ice cores, and 14C from tree rings, which are also dependent on solar activity.
In the period between 1250 and 1850, the regional temperatures in the Altai showed a high correlation with the reconstructed solar activity. This indicates that the changes in solar activity during this time were a main driver of temperature changes.

The temperature follows the sun
Interestingly, the regional temperatures followed the solar forcing with a time lag of 10 to 30 years. The PSI researchers’ study is the first in which such a delay has been observed over a period of more than 500 years. Since the influence of solar activity on climate has not yet been fully resolved, such observations provide an important contribution to its understanding. One possible mechanism discussed by various authors, which might explain this average lag of 20 years, is the indirect effect of the sun on temperature changes involving ocean-induced changes in atmospheric circulation. Ocean water warms up to a higher level in places where the solar radiation is most powerful, i.e. in the sub-tropics and the tropics. The heat energy is carried from the lower to the higher latitudes by the ocean, then released back into the atmosphere. Because of the high thermal capacity of the oceans and the variable velocities of their currents, these processes are subject to considerable delay. Changes in the North Atlantic atmospheric circulation system, which is responsible for temperature changes in the Altai, may be initiated 20 years earlier by changes of solar radiation in the tropical oceans.

Strong temperature increase in the 20th century can not be explained by the sun
“Our study distinguishes between the pre-industrial era (1250-1850) and the period covered by the past 150 years”, emphasises Anja Eichler, scientist at the Paul Scherrer Institute. “While changes in the solar activity were a main driver of temperature variations in the pre-industrial period, the temperatures in the Altai have shown a much higher rate of increase than that of solar activity during the past 150 years. The strong increase in the industrial period, however, correlates with the increase in the concentration of the greenhouse gas CO2 over this time. The results of our regional study indicate that changes in solar activity explain less than half of the increase in temperature in the Altai since 1850. This agrees with global studies, based on reconstructed northern hemispheric temperatures”, says the researcher.

This work was undertaken in a collaborative project between the Paul Scherrer Institute and the Eawag - Swiss Federal Institute of Aquatic Science and Technology, the Oeschger Centre for Climate Change Research, and the Department of Chemistry and Biochemistry at the University of Bern, together with the Institute for Water and Environmental Problems at Barnaul (Russia).

The Paul Scherrer Institute develops, builds and operates large and complex research facilities, and makes them available to the national and international scientific community. Its own work concentrates on solid-state research and material sciences, elementary particle physics, biology and medicine, energy research and environmental research. With a staff of 1300 and an annual budget of approximately CHF260 million, this is Switzerland’s largest research institution.

Contact:
PD Dr. Margit Schwikowski, PSI Laboratory for Radiochemistry and Environmental Chemistry, 5232 Villigen PSI, Switzerland; margit.schwikowski@psi.ch; Tel. 056 310 41 10
Dr. Anja Eichler, PSI Laboratory for Radiochemistry and Environmental Chemistry, 5232 Villigen PSI, Switzerland; anja.eichler@psi.ch; Tel. 056 310 2077

Original publication: A. Eichler, S. Olivier, K. Henderson, A. Laube, J. Beer, T. Papina, H.W. Gäggeler, and M. Schwikowski, Temperature response in the Altai region lags solar forcing, Geophysical Research Letters, doi:10.1029/2008GL035930, in press (2008).

Climate research in the Altai Mountains: the mountain guide Beat Rufibach and PSI researcher Margit Schwikowski remove the ice core from the drill (PSI/Susanne Olivier)		The research team in the Altai Mountains. In the background: the drill tent. (Aufnahme PSI/Patrick Ginot)

Comparison of the reconstructed temperatures in the Altai (deviation from mean), derived from the oxygen isotopes in the ice core (red) with solar modulation as a measure for solar activity from measurements of 10Be in polar ice cores (blue) and 14C in tree rings (green). Atmospheric CO2 concentrations are also shown (black). The solar modulation records are shifted by 20 years (average value of temperature delay from solar forcing). All the graphs show smoothed 10-year average values. The vertical line divides the pre-industrial era (1250-1850) from the last 150 years.

Click on pictures to enlarge.

Superconductivity and Magnetism

From rivals to partners

The wild world of quantum mechanics produces states that are not predicted by the classical theory of physics. Today’s edition of «Science» magazine includes a report of an astonishingly new type of state by an international team of scientists around physicist Michel Kenzelmann from the Paul Scherrer Institute in Switzerland.

The experiments were carried out at the Swiss Spallation Neutron Source (SINQ) at the Paul Scherrer Institute (PSI). The SINQ neutron beam can be used to investigate the internal properties of materials without their destruction. This method allows the observation of processes that are not visible by any other means.

Coupled superconductivity and magnetism in Cerium-Cobalt-Indium

The research team achieved a surprising breakthrough. They discovered that the investigated material, Cerium-Cobalt-Indium, can become magnetically ordered, but only if it is at the same time also superconducting. This discovery is particularly astounding, since these two phenomena usually compete. In Cerium-Cobalt-Indium, however, magnetic order can apparently only exist if the material is superconducting.

Interaction between magnetism and superconductivity

In electrical conductors, electric current is carried by electrons. This leads to a loss of energy as soon as electrons collide with the positive crystal ions in the conductors, deflecting them from their optimum path. The loss-free transportation of electricity in superconductors is based on the fact that electrons join up to form so-called “Cooper pairs”. Such electron pairs have completely different characteristics from individual electrons and behave entirely differently; they switch to a new quantum state. This state allows the Cooper pairs to “talk to each other” in order to avoid collisions. This is what makes it possible to transport electricity without any losses.

Electrons possess a magnetic moment, which can be pictured as a kind of compass needle. In a Cooper pair, the “compass needles” of the two electrons usually point exactly into opposing directions, thus cancelling out their magnetic effect. When a superconducting state is subject to a magnetic field, the magnetic moments of the electron pairs become disturbed. On the one hand, this happens because the magnetic field induces currents that break the Cooper pairs apart. On the other hand, this happens because the magnetic field disturbs the opposing alignment of the magnetic moments in a Cooper pair. If the magnetic field succeeds in inducing magnetism to a Cooper pair, the Cooper pair is broken up and superconductivity is lost. In many materials, therefore, magnetism and superconductivity compete.

According to Kenzelmann, scientist at PSI and professor at ETH Zurich, magnetism and superconductivity do not always exclude each other, but they only tolerate each other at the very most. «Superconductivity and magnetism behave like two rivals who compete for the same territory: they try limit or suppress the presence of their opponent.»

Superconducting induces magnetism

In their experiment, the researchers cooled a crystal made up of the elements cerium, cobalt and indium (CeCoIn5) to minus 273.1 degrees Celsius. All the atomic movements in the crystal cease at such low temperatures, and the electrons that are travelling through the material can join together to form Cooper pairs. This produces the superconducting electrical state, which makes it possible to transport the electricity without any loss of power.

The researchers discovered that a new type of superconducting state came about when high magnetic fields were applied. This was accompanied by magnetism, and was not destroyed by it. Although the coexistence of magnetism and superconductivity had already been observed in other cases, the new aspect of this cerium compound lies in the fact that the magnetism only appears during the superconducting phase, and disappears abruptly with the superconductivity at even higher magnetic fields. This surprising observation suggests that magnetism is driven and stabilised by superconductivity in this particular case.

«Our results show clearly that superconductivity is absolutely vital for this magnetism to occur. This study will help us to understand more clearly how the electron pairs form in magnetic superconductors in the first place. We hope that the information can then be used for technological applications in the future», explained Prof. Kenzelmann.

Reference:
M. Kenzelmann et al.;Coupled Superconducting and Magnetic Order in CeCoIn₅;
Science, Vol 321, 12 Sept. 2008

Contact for further information:
Prof. Dr. Michel Kenzelmann, Laboratory of Developments and Methods, PSI, Tel. +41 (0)56 310 53 81, michel.kenzelmann@psi.ch

		Superconductivity in the Q-phase of CeCoIn5 is directly coupled to magnetic order. In this phase, both orders can only exist together but not separately.
Click on picture to enlarge.

ETH Researchers determine atomic structure of the mammalian “fatty acid factory”

Promising targets for drug development

Zurich, 4 September 2008. Mammalian fatty acid synthase is one of the most complex molecular synthetic machines in human cells. It is a promising target for the development of anti-cancer and anti-obesity drugs and for the treatment of metabolic disorders. Researchers of ETH Zurich have determined the atomic structure of a mammalian fatty acid synthase.

Synthesis of fatty acids is a central cellular process that has been studied for many decades. Fatty acids are used in the cell as energy storage compounds, messenger molecules and as building blocks for the cellular envelope. Previously, individual steps of this process have been investigated using isolated bacterial enzymes. However, in higher organisms – except plants – fatty acid synthesis is catalyzed by large multifunctional proteins where many individual enzymes are brought together to form a “molecular assembly line”.

The atomic structure of a mammalian “fatty acid factory” is the result of many years of research at ETH Zurich
As described in this week’s issue of “Science” magazine, researchers at ETH Zurich, supported by the National Centre of Excellence in Research (NCCR) in Structural Biology of the Swiss National Science Foundation, determined the high-resolution structure of a mammalian fatty acid synthase using data collected at the Swiss Light Source (SLS) of the Paul Scherrer Institute (PSI). These results crown the efforts towards determining detailed structures of fatty acid synthases in higher organisms, a milestone for future investigations, that a relatively small group of scientist at ETH Zurich, consisting of Timm Maier, Marc Leibundgut and Simon Jenni in the laboratory of Prof. Ban, have been pursuing for a number of years. This topic of research was initiated at ETH in 2001 and the first papers describing architectures of fungal and mammalian fatty acid synthases appeared two years ago in Science. Last year, the atomic structures of two fungal fatty acid synthases and the mechanism of substrate shuttling and delivery in these multi-enzymes were published in the same magazine. The latest paper in this series describes the atomic structure of the mammalian fatty acid synthase. These results reveal the details of all catalytic active sites responsible for iterative fatty acid synthesis and show how the flexibility of this large multi-enzyme is used for transferring substrates from one enzymatic active site to the next.

Fatty acid synthases as drug targets?
Besides the fundamental scientific interest in the function of this multi-enzyme with a central role in primary metabolism, mammalian fatty acid synthase is also considered a promising drug target. Although most fat accumulated in animals and humans is delivered to cells by ingestion and not by de novo synthesis, compounds that inhibit the function of the mammalian fatty acid synthase induce weight reduction in animals, showing potential for the treatment of obesity and obesity-related diseases, such as diabetes and coronary disorders. Furthermore, due to the increased requirement for fatty acid synthesis in cancer cells, inhibitors of this enzyme have anti-tumor activity, making fatty acid synthase an attractive drug target for anti-cancer therapy.

Multi-enzymes: the ultimate organic chemists
Mammalian fatty acid synthase belongs to a large family of multi-enzymes, some of which are responsible for synthesis of complex natural products of outstanding medical relevance with antibiotic, anticancer, antifungal and immunosuppressive properties. The structure of mammalian fatty acid synthase reveals how different catalytic domains are excised or inserted in various members of this family to yield multi-enzymes capable of synthesizing a large variety of chemical products. It facilitates the design of novel molecular assembly lines for the production of novel compounds. In particular, engineering of novel multi-enzymes for the production of modified antibiotics is important in the fight against resistant strains of bacteria.

Contact:
Clemens Schulze-Briese
Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
E-Mail: clemens.schulze@psi.ch; Phone: +41 (0)56 310 45 33

ETH Life: http://www.ethlife.ethz.ch/archive_articles/080905_Ban_Paper_Synthase/index
Science: http://www.sciencemag.org/cgi/content/abstract/321/5894/1315

Click on picture to enlarge.

President of ETH Board visits PSI

Glarus attorney Fritz Schiesser (54) has served as President of the ETH Board since the beginning of January. Today on Monday, 4 February, Fritz Schiesser paid his first visit to PSI since assuming office. Interim Director Martin Jermann, designated PSI Director Joël Mesot, and other high-ranking PSI officials and researchers introduced Dr. Schiesser to the mysteries of energy research, proton therapy, the Swiss synchrotron light source SLS, and the neutron source SINQ. Fritz Schiesser was deeply impressed with the pioneering achievements of PSI in the field of proton therapy and the scanning technique developed by PSI. He praised the energy research conducted by the Competence Center for Energy and Mobility (CCEM) and its enormous potential for Swiss science and business, as well as the pooling of know-how in the energy field by the institutions of the ETH Domain.

Dr. Schiesser also showed particular interest in the plans for construction of a new x-ray free-electron laser (XFEL). This light source will provide PSI with new experimental possibilities in physics and materials and life sciences, thanks to extremely bright and ultra-short x-ray pulses. The XFEL facility has great potential for applications in the pharmaceutical and chemical industry, the electronics industry, and environmental technology. According to Fritz Schiesser, “With major research facilities like this, PSI continues to strengthen its excellent international reputation in the 20th year of its existence. As a user laboratory, PSI makes an important contribution to the ETH Domain and Switzerland as a location for higher education.”

Designated PSI Director Joël Mesot expressed his satisfaction with the first visit of the President of the ETH Board to Villigen: “With our light, neutron, and muon sources, we are able to strengthen the international competitiveness of PSI and the Swiss higher education location. We are pleased that, thanks to his 17 years of experience as a Member of the Council of States, President of the ETH Board Fritz Schiesser can provide the necessary political backing for our ambitious but strategically important investments.”

Florian Meyer, Communication ETH Board


The new President of ETH Board Fritz Schiesser, flanked by Interim Director Martin Jermann and designated PSI Director Joël Mesot (left).

New technology sharpens X-ray vision

Researchers at the Paul Scherrer Institute (PSI) and the EPFL in Switzerland have developed a novel method for producing dark-field X-ray images at wavelengths used in typical medical and industrial imaging equipment. Dark-field images provide more detail than ordinary X-ray radiographs and could be used to diagnose the onset of osteoporosis, breast cancer or Alzheimer’s disease, to identify explosives in hand luggage, or to pinpoint hairline cracks or corrosion in functional structures. Up until this point, dark-field X-ray imaging required sophisticated optics and could only be produced at facilities like the PSI’s 300m-diameter synchrotron. With the new nanostructured gratings described in this research, published online January 20 in "Nature Materials", dark-field images could soon be produced using ordinary X-ray equipment already in place in hospitals and airports around the world.

Link to full media release

Traditional X-ray image of a chicken wing.

More detailed dark-field image.

New discovery in superconductor research

Publication in «Science»

New insights on cataract formation

Proteins (modeled as spheres) in the eye lens forming clumps are the cause of cataract.

Using the tools and techniques of soft condensed matter physics, a research team from University of Fribourg and EPF Lausanne in Switzerland has demonstrated that a finely tuned balance of attractions between proteins keeps the lens of the eye transparent, and that even a small change in this balance can cause proteins to aggregate and de-mix. This leads to cataract formation, the world’s leading cause of blindness. This work could shed light on other protein aggregation diseases (such as Alzheimer’s disease), and may one day lead to methods for stabilizing protein interactions and thus preventing these problematic aggregations from occurring. In addition to unveiling new information about the interactions of the proteins in the eye lens, this benchmark study provides a framework for further study into the molecular properties and interactions of proteins.

First structure of a Rhesus family membrane protein solved

The determined structure of the Rhesus membrane protein.

Researchers at PSI, in collaboration with scientists in France and England, have solved the first structure of a Rhesus (Rh) protein and thereby shed new light on a group of proteins of great importance in human transfusion medicine. Transport of ammonium across cellular membranes is an important biological process and is regulated by special membrane spanning proteins when needed. Bacteria, fungi and plants use ammonium as nitrogen source and make use of Amt (ammonium transport) family proteins to enhance the ammonium uptake capacity under nitrogen starvation. Animals use a related family of proteins, known as the Rhesus (Rh) proteins, to move ammonium which is toxic in excess across cell membranes. In humans the Rh proteins are also responsible for the Rh+ blood type found in about 85% of the human population.

Contact: fritz.winkler@psi.ch, Phone +41 (0)56 310 42 58
Full PNAS paper (PDF)

Excursion in the wondrous Mirror World

Alice in Wonderland - does a mirror world also exist for matter?

In physics, mirror matter, is a hypothetical counterpart to ordinary matter and not be mixed up with antimatter. It could explain symmetry violations observed in several processes of ordinary elementary particles. Symmetry could be restored by so called mirror particles with exactly the same mass as ordinary elementary particles. The mirror matter could form planets, stars, and galaxies and yet shares only gravitational interactions with the matter of our universe. By coupling to that idea the overwhelming evidence from astrophysical observations indicating that a considerable amount of our universe is made of matter we simply cannot see, so called "dark matter", there arises a strong motivation to put the idea to an experimental test. Since only experiment can decide about the nature of the missing mass, physicists are actively searching for experimental evidence of mirror matter.

Contact: manfred.daum@psi.ch, Phone +41 (0)56 310 36 68;
klaus.kirch@psi.ch, Phone +41 (0)56 310 32 78
Link to PRL paper or as PDF

The early relatives of flowering plants

High-resolution phase-contrast X-ray images of fossil seeds

The emergence of flowering plants is regarded as a major botanical mystery. In the 22nd November edition of the scientific magazine «Nature», an international research team with participation from the Paul Scherrer Institute (PSI) publishes results that shed fresh light on this controversial question. New three-dimensional non-destructive imaging procedures have been used to carry out investigations into fossilised plant seeds. As a result, it has been possible to confirm an earlier scientific theory, which had previously been cast into doubt by molecular genetic analyses.

Link to full media release

Sectional view of a 120 million years old Early Cretaceous plant seed. Its complex inner structure was determined by means of phase-contrast X-ray microtomography at the TOMCAT beamline of the SLS (micron scale).		High-resolution imaging methods as the novel phase-contrast method for studying fossilised plant seeds are used for many research fields at the Swiss Light Source (SLS) of PSI. (Photo: H.R. Bramaz/PSI)

Important protein structure determined

CAP-Gly domains control fundamental cellular processes

Using biochemical, cell biological and biophysical information including X-ray crystallographic data collected at the Swiss Light Source (SLS) researchers at PSI, in collaboration with groups in Rotterdam and University of Zürich, now unraveled the molecular basis of CAP-Gly domain function which turned out to be conserved from yeast to man. Their findings further offer a basis for understanding the origin of hypoparathyroidism-retardation-dismorphysm and distal spinal muscular atrophy, two hereditary human diseases. The results were recently published in the renowned journal Nature Structural and Molecular Biology (Volume 14, No 10, pp. 959 - 967).

Many biological processes are controlled by the interaction of protein molecules within cells. These proteins often consist of module-like building blocks. One of these protein modules is the so-called CAP-Gly domain, which was discovered in 1993. Despite the implication of CAP-Gly domains in fundamental cellular processes such as cell division, cell migration and intracellular organelle and vesicle transport the underlying mechanism of their actual functions remained poorly understood.

NSMB Paper Structure-function relationship of CAP-Gly domains (PDF)

Structural basis of a solved CAP-Gly domain.

Year round proton radiation therapy at PSI using a new, dedicated cyclotron

A pioneer in proton therapy for the treatment of cancer, PSI has recently introduced one of the most advanced technologies in the field. A new proton accelerator, a superconducting cyclotron, has been put into operation for patient treatment. The accelerator is used in conjunction with a gantry, a device which delivers the protons to the patient from any angle. The desired dose distribution is achieved by scanning a small pencil beam of protons throughout the tumor. The performance of the new accelerator has been excellent since the start of medical operation.

Proton radiation therapy for deep seated tumors using a compact gantry with spot scanning technology was PSI’s unique contribution to particle radiotherapy worldwide. After 10 years of medical operation (over 260 patients were treated between 1996 and 2005) with PSI’s main accelerator as the beam source, we installed a dedicated proton accelerator for medical use. This relieved the medical program from yearly technical accelerator shut downs of several months and from limited beam availability per day and week, all of which were due to the complexity of a large research facility.

The dedicated proton accelerator (called the COMET) is a compact, superconducting 250 MeV cyclotron. The original design came from the National Superconducting Cyclotron Laboratory at Michigan State University and was adapted to PSI’s specifications and requirements. They included reliable all year round beam production for clinical operation of both the original gantry (Gantry 1) and the eye treatment facility as well as technical flexibilities to accommodate the next generation gantry which features advanced beam scanning and is presently under construction (Gantry 2). Gantry 2 is a further PSI development which will bring beam scanning to the forefront of the medical use of protons.

The cyclotron was fabricated by ACCEL Instruments GmbH (Varian) in Bergisch Gladbach, Germany, and was successfully installed, commissioned and connected to Gantry 1 in 2006/7. The collaboration between ACCEL and PSI resulted in a system that meets stringent specifications, including reliability and efficient maintenance. The technical performance of the cyclotron has met all expectations and the first patient was treated with Gantry 1 and COMET in February 2007. After a planned shut down for technical fine tuning between June and early August patient treatments have been resumed. Future medical operation will be year round.

Gantry 2, with advanced beam scanning and features allowing the treatment of moving targets, will be commissioned in 2008. It is anticipated that the sophisticated technology of COMET and Gantry 2 will determine the future state-of-the-art of proton radiation therapy. Technology transfer to industry and clinics who are interested in advanced proton therapy facilities is foreseen..

	For further information: Martin Jermann Acting Director Phone 056 310 27 18 E-Mail: martin.jermann@psi.ch
The compact cyclotron at PSI during installation. Click on the picture for a high resolution version (ca. 3 MB).

New interim Director at PSI

Leadership change at national research institute

From the 1st September Martin Jermann will take over as Acting Director of the Paul Scherrer Institute (PSI) until a permanent replacement is found. For years Head of Staff and a vice director of PSI, Jermann (59), an ETH physicist will continue to implement PSI’s strategy and ensure that goals set in current and planned research projects are reached. He relieves Ralph Eichler of the post who will take up the position of President of the ETH Zurich. The physics professor was PSI director since 2002 and, due to the breadth of his contacts, has situated PSI successfully on a national and international research level and has promoted collaboration with the universities, technical universities and industry. Likewise, the Head of Communication at PSI, Beat Gerber, moves to the ETH Zurich. This autumn he will take up the position of Communications Consultant to the President.

Link to full media release

Welcome greeting from the new Acting Director

Martin Jermann, Acting Director, PSI. Click on the picture for a high resolution version (ca. 2 MB).

Millions of multi stable devices in a network

Special supramolecular structures for future IT technology

Scientists from the National Centre of Competence in Research (NCCR) on Nanoscale Science at the Swiss Nanoscience Institute (SNI) have taken a further important step forward in the development of functional addressable supramolecular structures. In collaboration scientists from the Paul Scherrer Institute (Villigen, Switzerland), the University of Basel, and the Swiss Federal Institute of Technology (ETH) in Zurich have succeeded in creating a surface with millions of tiny multi stable devices. These switches, made of porphyrin molecules, about one nanometer in size, can be individually operated using the tip of a scanning tunnelling microscope. This work is published in the renowned international science journal Angewandte Chemie (International Edition).

In their studies, the scientists were primarily interested in extending the principles of self-assembly to produce addressable supramolecular structures and thus developing platforms for technical applications. The research teams from Villigen, Basel, and Zurich have established a well-defined arrangement of supramolecular structures which can be individually addressed. They have thus laid a further foundation stone for the creation of technical functions such as superior data storage units through the rapid and low-cost self-assembly of molecules.

Link to complete SNI Media release




Time lapse imaging sequence of supramolecular porous layer partially filled with ’molecular rotors’. Each image is taken 148 seconds after the previous. Each molecular rotor unit is formed by a porphyrin molecule nested on top of one pore of the porous layer and can be addressed by the coordinates. Above minus 160° C the molecules switch spontaneously between orientational positions (as denoted by the arrows). At lower temperatures, rotational switching can be locally induced by the tip of the scanning tunnelling microscope.

Click on the picture for a high resolution version. (ca. 0.5 MB).

Important protein-folding problem solved

Coiled coils comprise two to five polypeptide chain helices that wrap around each other to form a supercoiled protein structure. They are implicated in a wide range of fundamental biological processes including DNA transcription, signal transduction, and intracellular transport. Furthermore, more than 7 percent of all amino acids encoded by the human genome are thought to be engaged in coiled-coiled interactions. Using a multidisciplinary approach, researchers at PSI, in collaboration with groups in the UK, USA and University of Zurich, discovered and characterized a short amino acid sequence, termed the 'trigger sequence', that is indispensable for the folding of coiled coils. The work represents a major advance in understanding of how coiled coils assume their specific three-dimensional structure, opening opportunities for the design of bioactive proteins based on coiled-coil motifs. The results were recently published in the renowned journal PNAS.

PNAS publication "Molecular basis of coiled-coil formation", Vol. 104, No. 17 (PDF)

Neutrons for research and nuclear waste disposal

Key experiment for nuclear technology successfully completed

Megapie is an international pioneering experiment at the Paul Scherrer Institute (PSI) in Villigen, Switzerland, the goal of which is to produce neutrons from a liquid metal target when hit from a proton beam. In a world first, a high power neutron source was produced from about one megawatt of proton input. Neutrons of high initial energy are used in many research fields and could be used to incinerate nuclear waste. The first phase of the experiment was recently completed and to the great satisfaction of the international scientific community.

Full text of media release: English, français
Link to background information about Megapie (PDF): Deutsch, English, Italiano
Link to Megapie homepage

Key proteins illuminated by SLS

How cells regulate nitrogen uptake can be better understood.

Nitrogen uptake and metabolism is essential for living cells. The uptake mainly occurs through the most reduced form of nitrogen, ammonia. When nitrogen is limited, ammonia uptake in fungi, plants, archaea (ancient bacteria like organisms) and eubacteria is facilitated by a family of membrane proteins known as the ammonium transporters (Amt/Mep) family.

In collaboration with two UK groups, researchers at PSI have now determined the crystal structure of the complex between the ammonia channel AmtB and its regulatory protein GlnK. This marks a considerable advance in understanding nitrogen regulation in prokaryotic cells. (Prokaryotes are organisms without a cell nucleus). These results were recently published in the journal: Proceedings of the National Academy of Sciences of the U.S.A.

A new beamline is launched at the SLS

POLLUX beamline is an X-ray microscope on the nano-scale

With the inauguration of the POLLUX beamline, the Swiss Light Source (SLS) in Villigen, Switzerland gains its tenth experimental station, providing scientists with another tool to access the nanoworld. An X-ray lens focuses the SLS light beam to 30 nanometres. This allows the measuring of chemical maps on the nanometre scale. Such analyses serve materials science in the study of magnetism in nanostructures, which could ultimately lead to new magnetic storage systems.

Environmental science will also benefit from the POLLUX beamline. For example the study of millions of year-old pollen which holds secrets of the earth’s history and the process of fossilisation. Fine particulate matter or aerosol particles can be made visible and their chemical composition and reactivity can be analysed.

One technical challenge at POLLUX is to focus the 30 nanometre X-ray beam on the sample between the Fresnel zone plates. These X-ray lenses have the diameter of a human hair, (0.15 millimetres) and consist of many hundreds of concentric gold rings created by a nano-lithographic process.

The new beamline is a joint project of the University of Erlangen-Nuremberg and PSI. The financing of 1.6 Million Euros comes from PSI and the German Federal Ministry of Education and Research. This is the tenth beamline for the five year-old SLS, and ten more beamlines are planned.

For scientific information:
Dr. Christoph Quitmann, Head of Laboratory, LSYII, SLS, PSI; Tel: +41 (0)56 310 45 60; christoph.quitmann@psi.ch
Dr. Jörg Raabe, Beamline scientist, PSI; Tel: +41 (0)56 310 51 93; joerg.raabe@psi.ch

A successful tool for top research

The Swiss Light Source (SLS) started operating five years ago in Villigen, Switzerland. Since then, the facility at the Paul Scherrer Institute (PSI) has been available for use by researchers from universities and industry. The SLS generates beams of light which are extremely fine and highly intensive. The facility acts as both a gigantic microscope and a multi-coloured micro-spotlight. It enables researchers to penetrate hitherto unexplored microcosmic depths. For example, it can help them decode the structure of proteins, or explore the characteristics of superconductors – and all at magnitudes of thousandths of a millimetre.

In 2005, 830 researchers undertook a total of 677 experiments. These scientists mainly come to PSI from Switzerland, Germany, Italy and France; and they include biologists, chemists, physicists, environmental scientists and geologists. And still they come! Since the SLS went into operation with four beamlines, the rate of occupation has increased steadily. There are now ten beamlines in operation and they are so popular that the demand for measuring time outstrips supply several times over. By 2010, there should be eighteen to twenty beamlines in operation.

The SLS is the most advanced synchrotron light source in the world. The beam provided here is very brilliant and extremely stable, which gives better experimental results. This premium quality is based on new technologies that were developed at PSI and have frequently been copied since then. The construction of the SLS has already paid its way in the form of research published in scientific journals. According to Timothy Richmond winner of the 2006 Marcel Benoist Prize; “The SLS is one of the best facilities in the world, and has advanced my work”. Richmond is a Professor at the ETH in Zurich, and was honoured with the “Swiss Nobel Prize” for clarifying the structure of nucleosomes, the basic units of chromosomes.

For technical information about the SLS please contact:
Dr. Heinz Weyer, heinz.weyer@psi.ch: Tel: (0041) (0) 56 310 34 94

Progress in imaging techniques

Innovations for society

Imaging techniques are increasingly at the forefront of progress in science and technology. The Paul Scherrer Institute (PSI) is among the leaders in this development. Imaging techniques turn objects visually inside out, allowing ever greater precision – for instance in medical diagnosis. They also contribute to a better understanding of the mechanisms of certain diseases, like Alzheimer's or osteoporosis. Further applications occur in materials research, where imaging processes are a decisive factor in achieving results that ultimately – as with medical progress – benefit society.

Link to the Media release
Nature Physics Paper
Presentation EUSJA study trip