Press releases – March 2015

FRANKFURT.Optogenetics is a new field of research that introduces light-sensitive proteins into cells in a genetically targeted manner, for example, to obtain information on signalling pathways and the function of neurons in a living organism. A new priority program supported by the German Research Foundation (DFG) under the auspices of Goethe University has now set itself the goal of developing the next generation of optogenetic tools and expanding their application both in basic research and also for medical purposes. DFG will provide six million Euros in funding for the programme over the next three years.

"We see our role as a pathfinder, to build a scientific network for optogenetics in Germany," says Prof. Alexander Gottschalk, spokesperson for the priority programme "Next generation optogenetics: Tool development and applications". After an application phase in the autumn of 2015, between 30 and 40 scientists from different universities will become involved; primarily biophysicists, cell biologists, chemists, medical scientists, and "photo-biologists." These are the types of specialists who will search for new, light-sensitive proteins, which will be introduced into cells and act like light switches to turn cellular processes on and off.

"Optogenetics already has many applications in basic research, but as a technology it is still in its infancy," explains Gottschalk. In order to achieve more widespread use of optogenetics in cell biology and neurobiology, the researchers want to develop new optogenetic tools. These will have higher light sensitivity, clarify the processes within individual cells and between different cells, and ultimately also be tested in animal models. This is necessary, especially with regard to medical applications; for example, for the enabling treatment of certain vision and hearing impairments or aspects of previously incurable diseases, such as Parkinson’s disease, seizure disorders, or cardiac diseases.

The scientists are placing special importance on informing the public about the opportunities and risks of optogenetics. This will be done through intelligible presentations for the lay public, and through articles on websites such as www.OpenOptogenetics.org, http://dasgehirn.info, and the future website of the research programme.

Information: Prof. Alexander Gottschalk, Institute for Biochemistry, Campus Riedberg, Tel.: (069) 798-42518, a.gottschalk@em.uni-frankfurt.de.

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FRANKFURT/DARMSTADT. It has long been proven that people who follow a Mediterranean diet and keep physically and mentally active are less likely to suffer from dementia. Olives in particular appear to play a key role in this regard. But just what are the substances contained in these small, oval fruit that are so valuable? This is what a Hessen-based group of researchers from the Goethe University Frankfurt, the Technical University (TU) of Darmstadt and Darmstadt company N-Zyme BioTec GmbH intends to find out. The three-year project “NeurOliv” has a project volume of 1.3 million Euros and is funded by the Federal Ministry of Education and Research as part of the high-tech initiative "KMU-innovativ Biochance".

This collaboration combines a number of approaches, the initiative of which came from N-Zyme BioTec GmbH. The aim is to use substances contained in olives to develop new functional food for the ageing society, which will protect against Alzheimer’s disease. “We want to test whether olive polyphenols can even help to cure the disease. This is why we believe our products also relate to the pharmaceutical sector”, says Dr. Joachim Tretzel, Managing Director of N-Zyme BioTec GmbH. The high-tech initiative of the German government was set up to fund small and medium-sized enterprises.

The team, led by Prof. Heribert Warzecha of the Department of Biology of TU Darmstadt, is examining the development of new biotechnological processes designed to extract specific plant substances. With the relevant genetic information, bacterial cultures are said to help bring out substances in a pure and defined form. “Our new techniques make it easier to extract substances from olive leaves and significantly improve low yields“, explains Warzecha. “When it comes to production, this means we aren’t dependent on the seasonal harvesting of olives in growing areas”, adds Dr. Stefan Marx, also Managing Director of N-Zyme BioTec.

The “nutritional-neuroscience” working group of Dr. Gunter Eckert, food chemist and private lecturer at the Goethe University Frankfurt (GU), will test the effectiveness of these biotechnologically produced olive substances. Firstly, olive substances will be tested in cell culture models, which may protect against Alzheimer’s disease. “We focus on changes to the power houses of nerve cells (mitochondria), which change early on in Alzheimer’s disease”, says Eckert. The most active compounds should then demonstrate in a mouse model of the disease that they can improve brain function.
“We are testing the hypothesis that certain polyphenols from olives slow down disease processes in the brain, improve mitochondrial dysfunction and, as a result, provide evidence to suggest they protect against Alzheimer’s disease”, explains pharmacological expert Eckert, summarizing the objective of his research. GU researchers have been awarded funding of 288,000 Euros for the project. In another research project, Eckert is examining the relationship between diet and exercise with regard to the development of Alzheimer’s disease.

Download images from: www.uni-frankfurt.de/54645204

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FRANKFURT. The discovery of the soccer ball-shaped C₆₀ molecule in 1985 was a milestone for the development of nanotechnology. In parallel with the fast-blooming field of research into carbon fullerenes, researchers have spent a long time trying in vain to create structurally similar silicon cages. Goethe University chemists have now managed to synthesise a compound featuring an Si₂₀ dodecahedron. The Platonic solid, which was published in the "Angewandte Chemie" journal, is not just aesthetically pleasing, it also opens up new perspectives for the semiconductor industry. 

The Si₂₀ dodecahedron is roughly as large as the C₆₀ molecule. However, there are some crucial differences between the types of bonding: All of the carbon atoms in C₆₀ have a coordination number of three and form double bonds. In the silicon dodecahedron, in contrast, all atoms have a coordination number of four and are connected through single bonds, so that the molecule is also related to dodecahedrane (C₂₀H₂₀). "In its day, dodecahedrane was viewed as the 'Mount Everest' of organic chemistry, because it initially could only be synthesized through a 23- step sequence. In contrast, our Si₂₀ cage can be created in one step starting from Si₂ building blocks," explains Prof. Matthias Wagner of the Goethe University Institute of Inorganic and Analytical Chemistry.

The Si₂₀ hollow bodies, which have been isolated by his PhD student, Jan Tillmann, are always filled with a chloride ion. The Frankfurt chemists therefore suppose that the cage forms itself around the anion, which thus has a structure-determining effect. On its surface, the cluster carries eight chlorine atoms and twelve Cl₃Si groups. These have highly symmetric arrangements in space, which is why the molecule is particularly beautiful. Quantum chemical calculations carried out by Professor Max C. Holthausen's research group at Goethe University show that the substitution pattern that was observed experimentally indeed produces a pronounced stabilisation of the Si₂₀ structure. 

In future, Tillmann and Wagner are planning to use the surface-bound Cl₃Si anchor groups to produce three dimensional nanonetworks out of Si₂₀ units. The researchers are particularly interested in the application potential of this new compound: "Spatially strictly limited silicon nanoparticles display fundamentally different properties to conventional silicon wafers," explains Matthias Wagner. The long strived-for access to siladodecahedrane thus opens up the possibility of studying the fundamental electronic properties of cage-like Si nanoparticles compared to crystalline semiconductor silicon.

Publication:
J. Tillmann et al: One-Step Synthesis of a [20]Silafullerane with an Endohedral Chloride
Ion, in: Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201412050

Download an image from: http://www.muk.uni-frankfurt.de/54612947?

Information: Prof. Matthias Wagner, Institute for Anorganic and Analytic Chemistry, Campus Riedberg, phone: +49(069)798-29156, email: Matthias.Wagner@chemie.uni-frankfurt.de

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FRANKFURT.Are leaves and buds developing earlier in the spring? And do leaves stay on the trees longer in autumn? Do steppe ecosystems remaining green longer and are the savannas becoming drier and drier?  In fact, over recent decades, the growing seasons have changed everywhere around the world. This was determined by a doctoral candidate at the Goethe University as part of an international collaboration based on satellite data. The results are expected to have consequences for agriculture, interactions between species, the functioning of ecosystems, and the exchange of carbon dioxide and energy between the land surface and the atmosphere.  

"There is almost no part of the Earth that is not affected by these changes", explains Robert Buitenwerf, doctoral candidate at the Institute for Physical Geography at the Goethe University. He has evaluated satellite data from 1981 to 2012 with regard to 21 parameters on vegetation activity, in order to determine the point in time, the duration, and the intensity of growth from the northernmost conifer forests to tropical rain forests. His conclusion: On 54 percent of the land surface, at least one parameter of vegetation activity has moved away from the mean value by more than two standard deviations.

As reported by researchers from Frankfurt, Freiburg and New Zealand in the current edition of the professional journal "Nature Climate Change", leaves are now sprouting earlier in most of the climate zones of the far north. Although they are also dropped somewhat earlier in autumn, the overall vegetation period has grown longer. On the other hand, in our latitudes, trees and shrubs are losing their leaves later than they have up to now.

To date, not much research has been conducted on the regions of the southern hemisphere.  In those areas, the researchers found that in several savannas of South America, southern Africa and Australia, the vegetation activity has decreased during dry seasons. "Although these savannas have similar vegetation and comparable climates, the changes in vegetation activity differ. That may be attributable to the differences in the functioning of the respective ecosystems", says Buitenwerf.

In this respect, the seasonal distribution of leaf growth constitutes a sensitive indicator: it indicates how various ecosystems react to changes in the environment. "Although vegetation changes in the northern hemisphere have conclusively been attributed to climate change by other studies, attributing all the changes found in our study would require a more complex analysis," Buitenwerf emphasizes. In the northern hemisphere it has already been shown that species whose life cycles depend on the vegetation period are endangered by these severe changes.  Consequences for species in the southern hemisphere are as yet unclear.

Publication:
Robert Buitenwerf, Laura Rose and Steven I. Higgins: Three decades of multi-dimensional change in global leaf phenology, in: Nature Climate Change, March 2 2015,
DOI: 10.1038/NCLIMATE2533.

Information:
Robert Buitenwerf, Landcare Research, Lincoln, New Zealand. Tel: +6433219706, buitenwerfrobert@hotmail.com

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FRANKFURT. It has not yet been possible to measure the gravitational waves predicted by Einstein's theory of general relativity. They are so weak that they get lost in the noise of the measurements. But thanks to the latest simulations of the merging of binary neutron star systems, the structure of the sought-after signals is now known. As a team of German and Japanese theoretical astrophysicists reports in the Editor’s choice of the current edition of the scientific journal "Physical Review D", gravitational waves have a characteristic spectrum that is similar to the spectral lines of atoms.

Gravitational waves are generated when masses accelerate. The first indirect evidence for their existence was detected in 1974 when the binary pulsar PSR B1913+16 was discovered in the constellation Aquila. The two rapidly rotating neutron stars are drifting towards each other in a spiral shape, which is why, the astrophysicists explain, they are losing energy and emitting gravitational waves. Russell A. Hulse and Joseph H. Taylor received the 1993 Nobel Prize in Physics for this discovery. In the meantime, there are now several large-scale experiments for detecting gravitational waves: the American LIGO experiment, the European Virgo experiment, and the Japanese KAGRA detector. Experts estimate that signals of gravitational waves from merging binary neutron star systems will be detected within the next five years.

"These signals are not easy to detect, because they have an extremely small amplitude." But despite these difficult conditions, it is possible to find them, if you know what to look for in advance," explained Professor Luciano Rezzolla from the Institute for Theoretical Physics at Goethe University. Together with a Japanese colleague from Osaka University, he has studied a number of binary neutron star systems with the help of the latest simulation techniques and has discovered that the merging of the stars generates characteristic gravitational wave spectra. "These spectra correspond, at least logically, to the electromagnetic spectral lines emitted by atoms or molecules. From these we can derive information on the characteristics of the stars," explains Rezzolla.

As the astrophysicists show in two publications with related content in "Physical Review Letters" (published in November 2014) and in the current edition of "Physical Review D," the gravitational waves spectrum is like a fingerprint for the two stars. If scientists learn how to interpret these spectra, they will know what the neutron stars are made of and will be able to determine what is their equation of state, which is so far unknown. Equations of state describe the thermodynamic properties of systems as a function of variables, such as pressure, temperature, volume, or particle number. To this Rezzolla adds: "This is a very exciting possibility, because then we would be able to solve a riddle that has remained unsolved for 40 years: What are neutron stars made of and what is their stellar structure?"

 "If the signal is strong and thus the fingerprint is very clear, even a single measurement would be sufficient," Rezzolla predicts. "The prospects of solving the riddle of neutron stars have never been this good. The gravitational waves that we hope to detect in a few years are already on their way from the farthest reaches of the universe."

You can download images at: www.uni-frankfurt.de/54497071

Caption: Four snapshots from the merging of two neutron stars. Convergence to merger takes only a few milliseconds, during which immense masses are accelerated. The signals of the theoretically generated gravitational waves have now been calculated in simulations.

Publication:
K. Takami, L. Rezzolla, and L. Baiotti, Constraining the Equation of State of Neutron Stars from Binary Merger, Phys. Rev. Lett. 113, 091104 (2014).

DOI: 10.1103/PhysRevLett.113.091104

K. Takami, L. Rezzolla, and L. Baiotti, Spectral properties of the post-merger gravitational-wave signal from binary neutron stars, Phys. Rev. D. 113, 091104 (2015), 2. März 2015.

Information:
Prof. Luciano Rezzolla, Institute for Theoretical Physics, Campus Riedberg, Tel.: (069) 798-47871, rezzolla@th.physik.uni-frankfurt.de.

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