Press releases

FRANKFURT. Translation of the genetic code in proteins is a central process in life and takes place in the ribosome, a giant molecule consisting of two subunits. This is where long chains of amino acids are formed like on an assembly line. An interdisciplinary research group from Goethe University Frankfurt, the EMBL in Heidelberg, and the Gene Center of the University of Munich (LMU) has now succeeded in solving the structure of a central player in this process bound to the small ribosomal subunit: the protein containing a unique iron-sulphur domain with the nickname “Iron Hammer” splits the two subunits of the ribosome when a protein chain is completed so that production of a new protein can begin.

The two subunits of the ribosome have to be actively split once the protein chain is complete otherwise errors occur in mRNA translation: research ignored this fact for a long time. Central player in this “ribosome recycling” process is the essential and highly dynamic metalloenzyme ABCE1. The iron-sulphur domain of ABCE1, known as the “Iron Hammer”, rotates and presses the ribosomal subunits apart like a lever.

To uncover this, the research group led by Professor Robert Tampé at the Institute of Biochemistry at Goethe University Frankfurt isolated a complex of the small ribosomal subunit with ABCE1 (post-splitting complex) by means of an innovative preparation method. This complex was chemically fixed and cut into pieces, while the original distance information was preserved.

At the EMBL in Heidelberg, the researchers used highly advanced mass spectrometry to analyse these small fragments and relate them to each other revealing their original distances on nanometre scale. The group in Munich then examined the reconstructed complex with a high-resolution cryogenic electron microscope and was able to reconstruct a 3D model of the post-splitting complex with tightly bound ABCE1 from a vast collection of single-particle images.

Professor Robert Tampé summarizes the significance of these results: “We have forced the rebellious and aggressive multi-domain enzyme ABCE1 into a new, unexpected state on the ribosome and used the combined expertise of three institutes to enrich textbook knowledge for coming generations of students.”

Publication: Kristin Kiosze-Becker, Alessandro Ori, Milan Gerovac, André Heuer, Elina Nürenberg-Goloub, Umar Jan Rashid, Thomas Becker, Roland Beckmann, Martin Beck & Robert Tampé (2016): Structure of the Ribosome Post-Recycling Complex Probed by Chemical Cross-Linking and Mass Spectrometry. Nature Communications, doi: 10.1038/NCOMMS13248

Further information: Professor Dr. Robert Tampé, Institute of Biochemistry, Riedberg Campus, Tel.: +49(0)69-798-29475, tampe@em.uni-frankfurt.de.

FRANKFURT. Regulatory authorities around the world can in future instruct manufacturers of chemicals and drugs to check their products for harmful effects on reproduction by means of a new test with molluscs. After over 10 years of funding by the German Environment Agency in Dessau, a project coordinated by Goethe University Frankfurt has now resulted in an OECD guideline (Organisation for Economic Co-operation and Development) for global chemical testing. The test analyses in the laboratorythe long-term effects of chemicals on reproduction in freshwater mudsnails (Potamopyrgus antipodarum).

“Although this tiny creature is not an indigenous snail species, as what is known as a “model organism” its biological answers are also transferable to other molluscs, regardless of whether they stem from Europe, Asia or America”, explains Professor Jörg Oehlmann, coordinator of the test development team and head of the Department of Aquatic Ecotoxicology at Goethe University Frankfurt. Potamopyrgus is a water dweller and was introduced to Europe in the mid 19^th century on board ships from New Zealand. However, this alien species is meanwhile part of the normal landscape in many of Europe’s watercourses.

New chemicals which have not yet been approved and harm the mudsnail in OECD Test No. 242 in the laboratory would have the same effect on it and related species in the wild. Since molluscs, after insects and crustaceans, are the second most species-rich group in the animal kingdom, the loss of these organisms would be fatal for biodiversity and thus also for the correct functioning of the ecosystems. The development of the “snail test” therefore constitutes an important contribution to keeping our watercourses clean and healthy, since substances which show a toxic effect in this test for the snail can in future be identified and controlled prior to market introduction.

In addition, the new snail test closes an existing gap in the environmental risk assessment of chemicals, since standardized tests with invertebrates to date focussed mainly on arthropods (insects and crustaceans). Snails had, however, in the past proven to be extraordinarily sensitive to a large number of harmful substances, including tributyltin compounds and other environmental chemicals which influence the hormone system.

The work coordinated by Goethe University Frankfurt on the development and standardization of the snail test took place over a period of more than 10 years. Test conditions for the snails with regard to water and feedstuff quality, temperature, concentration and numerous other parameters were optimized in the framework of an extensive research programme. In the last six years, four final validation studies with six test substances were carried out in 16 laboratories in Europe and the USA which showed that the test protocol developed is robust and the test generates reproducible results, independent of in which laboratory it is implemented.

For the test, female mudsnails are exposed to a concentration range of chemicals in ambient water. The organisms remain with the test substance in their test beakers for 28 days, after which the number of embryo amongst all surviving females is counted. “It’s a process which is easy to use and also suitable for everyday use by water authorities”, says Oehlmann.

In their home country of New Zealand, both male and female mudsnails are found. In Europe, however, populations are composed solely of females which reproduce parthenogenetically. This makes using the test and analysing the results easier, all the more so since the tiny snail makes only modest demands on the laboratory. “The animal’s small size has another advantage: in comparison to many other test procedures, this test can be miniaturized and doesn’t take up much space”, explains Oehlmann. That makes it possible to test a larger number of chemicals.

Further information: Prof. Dr. Jörg Oehlmann, Department of Aquatic Ecotoxicology, Riedberg Campus, Tel.: +49(0)69-798-42142, oehlman@bio.uni-frankfurt.de

OECD guideline 242 for the testing of chemicals: http://dx.doi.org/10.1787/9789264264311-en.

FRANKFURT/KASSEL/SAARBRÜCKEN. How can the enormous amounts of electricity generated through offshore wind power be temporarily stored on site? Until now there was no answer to this question. After several years’ research work, the StEnSea project (Stored Energy in the Sea) funded by the Federal Ministry for Economic Affairs and Energy is now entering the test phase. In the framework of this project, IWES, the Fraunhofer institute in Kassel specialized in energy system technology, is now developing to application level the “marine egg” invented by two physics professors at Goethe University Frankfurt and Saarland University in Saarbrücken.

A model on the scale of 1:10 with a diameter of about three meters was brought to the ferry terminal in Constance on 8.11.2016 and lowered on 9.11.2016 to a depth of 100 meters about 200 meters from the shore in Überlingen. It will now be tested for four weeks: “Pumped storage power plants installed on the seabed can use the high water pressure in very deep water to store electrical energy with the aid of hollow spheres”, explains Horst Schmidt-Böcking, emeritus professor at Goethe University Frankfurt. To store energy water is pumped out of the sphere using an electric pump and to generate power water flows through a turbine into the empty sphere and produces electrical energy via a generator. Together with his colleague Dr. Gerhard Luther from Saarland University, Professor Schmidt-Böcking filed a patent for their principle for offshore energy storage in 2011, just a few days before the Fukushima disaster.

The two inventors remember: “The rapid practical realization of our idea is actually thanks to a newspaper article in the FAZ. Georg Küffner, the technology editor, presented our idea for energy storage to the general public - as chance would have it on the 1^st of April 2011. Lots of readers doubtlessly thought at first that it was an April Fool hoax, but experts at Hochtief Solutions AG in Frankfurt immediately recognized the idea’s hidden possibilities. Within a couple of weeks we were able to set up a consortium for an initial feasibility study with Hochtief’s specialists for concrete structures and the experts in marine power and energy storage at IWES in Kassel, the Fraunhofer Institute for Wind Energy and Energy System Technology”, recall Schmidt-Böcking and Luther.

Once the concept’s feasibility had been proven, the Federal Ministry for Economic Affairs and Energy subsequently funded the StEnSea project so that the innovative pumped storage system could be further developed and tested on a model scale. It is now entering the test phase. Project Manager Matthias Puchta from Fraunhofer IWES summarizes the project’s successes to date: “On the basis of our preliminary study, we carried out a detailed systems analysis with a design, construction and logistics concept for the pressure tank, developed a turbine-pump unit, examined how to connect the sphere to the electricity grid, calculated profitability and drew up a roadmap for the system’s technical implementation.”

He continues: “The four-week model trials on the scale of 1:10 are starting now in Lake Constance. We will run various tests to check all the details concerning design, installation, configuration of the drivetrain and the electrical system, operation and control, condition monitoring as well as dynamic modeling and simulation of the system as a whole.”

IWES Head of Division Jochen Bard, who has been involved in marine power research for many years at both national and international level, explains: “With the results from the model trials, we want first of all to look more closely at suitable sites for a demonstration project in Europe. We are aiming at a sphere diameter of 30 meters for the demonstration-scale system. At the moment that’s the most practical size in terms of engineering. What’s already certain is that the system can only be used economically in the sea at depths of about 600-800 meters upwards. Storage capacity with the same volume increases linearly with the depth of the water and at 700 meters is about 20 megawatt hours (MWh) for a 30 m sphere.”

He continues: “There is great potential for the use of marine pumped storage systems in coastal areas, in particular near the coast in highly populated regions too, for example in Norway (Norwegian Trench). But Spain, the USA and Japan also have great potential. With a storage capacity of 20 MWh per sphere and standard technology available today, we can envisage a total electricity storage capacity of 893.000 MWh worldwide. This would make an important and inexpensive contribution to compensating fluctuations in electricity generation from wind and solar power.”

Media contact: Uwe Krengel, Tel. +49(0)561-7294-319 (or -345); email: uwe.krengel@iwes.fraunhofer.de

Further information: Dr. Horst Schmidt-Böcking, Tel. +49(0)69-798-47002 or +49(0)6174-934097; email: hsb@atom.uni-frankfurt.de

FRANKFURT. Microbes are already used on a wide scale for the production of fuels and base chemicals, but for this most of them have to be “fed” with sugar. However, since sugar-based biotechnology finds itself in competition with food production, it is faced with increasingly fierce criticism. Carbon dioxide has meanwhile become the focus of attention as an alternative raw material for biotechnological processes. Goethe University Frankfurt has now taken charge of a collaborative European project, the aim of which is to advance the development of processes for microbial, CO₂-based biotechnology. The project will be funded over the next three years with two million Euro.

“This application-oriented work is the logical continuation of our successful endeavours over many years to understand the metabolism of CO₂-reducing acetogenic bacteria. We can now start to steer their metabolism in such a way that they produce valuable substances and fuels which are interesting for mankind”, says Professor Volker Müller, professor at the Institute of Molecular Biosciences of Goethe University Frankfurt. He is coordinating this transnational project in the framework of the “Industrial Biotechnology” European Research Area Network (ERA-NET), within which the German research groups are financed by the Federal Ministry of Education and Research. This means that Goethe University Frankfurt now plays a pivotal role in the development of a next-generation technology.

The special group of acetogenic bacteria converts carbon dioxide (CO₂) in a fermentation process which is independent of light and oxygen. The bacteria use hydrogen (H₂) or carbon monoxide (CO) or a mix of both (synthesis gas) as a source of energy. However, the bacteria produce very little cellular energy in this metabolic process. This drastically limits the product range possible with gas fermentation, so that at present only acetic acid and ethanol can be manufactured on an industrial scale. That is why the collaborative European project has set itself the objective of genetically modifying suitable acetogenic bacteria in such a way that these energetic barriers can be overcome. Partners in the consortium are Goethe University Frankfurt as well as the universities in Ulm, Göttingen and La Coruna. ArcelorMittal, the largest steel manufacturer worldwide, is the industrial partner.

This microbial, CO₂-based biotechnology could in future be an environmentally friendly alternative for the reprocessing of industrial waste gases rich in energy and carbon and reduce our dependency on crude oil. The microbial fixation and transformation of CO₂ into raw materials produced biologically additionally makes it possible to reduce greenhouse gas emissions.

A diagram can be downloaded from: www.uni-frankfurt.de/63820642

Acetogenic (acetic acid-producing) bacteria produce acetic acid or ethanol from H₂ + CO₂ or CO. Energy is released in the form of ATP (adenosine triphosphate) in the process. The synthesis of other products interesting for industry from the intermediate product acetyl-CoA, however, also uses up ATP. The aim of this project is to alter the energy balance of the bacteria by means of genetic modification in such a way that the production of such energy-consuming compounds will also be possible.

Further information: Professor Dr. Volker Müller, Institute of Molecular Biosciences, Riedberg Campus, Tel.: ++49(0)69-798-29507, VMueller@bio.uni-frankfurt.de.

FRANKFURT. When new particles develop in the atmosphere, this influences cloud formation and with that the climate too. Since a few years, these complex processes have been reproduced in a large air chamber within the CLOUD experiment at CERN. Researchers have now used the results for the first time to calculate the production of aerosol particles in all the Earth’s regions and at different heights. The study published in the journal “Science”, in which researchers from Goethe University Frankfurt were involved, deciphers the role of the various chemical systems which are responsible for particle formation. They also determined the influence of ions which develop through cosmic radiation.

Soot particles, dust lifted up by the wind or sea spray account for only some of the particles in the atmosphere. Others develop from certain trace vapours, for example when individual sulphuric acid and water molecules cluster as tiny droplets. This formation of new particles is known as nucleation. Clouds are formed by water condensing on the larger aerosol particles or what are known as cloud condensation nuclei. The more cloud droplets develop, the more sunlight is reflected back into space. Climate models show that the additional particles caused by human activity produce a cooling effect which partially offsets the greenhouse effect. It is, however, less than previously assumed.

Aerosol particles from sulphuric acid and ammonia emissions

The model calculations presented in “Science” prove that about half the cloud condensation nuclei in the atmosphere originate from nucleation. In the atmosphere today, particle formation is dominated almost everywhere by mechanisms where at least three chemical components must come together: apart from the two basic substances, i.e. sulphuric acid and water, these are either ammonia or specific organic compounds such as oxidation products from terpenes. Close to ground level, organic substances from natural sources are important, whilst ammonia plays a key role higher up in the troposphere. Ammonia and sulphur emissions have increased considerably over the past decades as a result of human activities.

11-year solar cycle has scarcely any influence

CLOUD has also investigated how the 11-year solar cycle influences the formation of aerosol particles in our present-day atmosphere. The model calculations show that the effects as a result of changes in ionisation through the sun are too small to make a significant contribution to cloud formation. Although the ions are originally involved in the development of almost one third of all newly formed particles, the concentration of the large cloud condensation nuclei in the course of the 11-year cycle changes by only 0.1 percent – not enough to have any sizeable influence on the climate.

Cooling effects 27 percent less than expected

The CLOUD team has also presented first global model calculations for aerosol formation caused without the involvement of sulphuric acid and solely through extremely low volatile substances of biological origin (Gordon et al., PNAS). According to the findings, this process contributed significantly to particle formation above all in the pre-industrial atmosphere, since at that time far less sulphur components were released into the atmosphere. The number of particles in the pre-industrial atmosphere is now estimated to be far greater through the additional process than was shown in earlier calculations. The model calculations, which are based on data from the CLOUD experiment, reveal that the cooling effects of clouds are 27 percent less than in climate simulations without this effect as a result of additional particles caused by human activity: Instead of a radiative effect of -0.82 W/m² the outcome is only -0.60 W/m².

E.M. Dunne, et al., 2016: Global particle formation from CERN CLOUD measurements, Science First Release, DOI: 10.1126/science.aaf2649

This article appeared online via First Release in Science on Thursday, 27^th of October 2016. http://science.sciencemag.org/cgi/doi/10.1126/science.aaf2649

H. Gordon, et al., 2016: Reduced anthropogenic aerosol radiative forcing caused by biogenic new particle formation, PNAS, 113 (43) 12053-12058; published ahead of print on the 10^th of October 2016, DOI:10.1073/pnas.1602360113
http://www.pnas.org/content/113/43/12053.abstract

A photograph can be downloaded from: http://www.muk.uni-frankfurt.de/63775996

Further information: Prof. Dr. Joachim Curtius, Institute of Atmospheric and Environmental Sciences, Riedberg Campus, Tel.: ++49(0)798-40258, curtius@iau.uni-frankfurt.de