Press releases

FRANKFURT. According to the two main producers – China and India – the release of the potent greenhouse gas HFC-23 into the atmosphere should have almost completely stopped by 2017. However, the reality is that a team of atmospheric researchers led by the University of Bristol has measured record levels. Dr Kieran Stanley, lead author of the study published in the current issue of “Nature Communications", has been working at Goethe University for six months. 

Over the past two decades, researchers have monitored the concentration of the hydrofluorocarbon HFC-23 very closely. “It is a very potent greenhouse gas: The emission of one tonne of this substance does just as much damage as the emission of 12,000 tonnes of carbon dioxide," says atmospheric researcher Professor Andreas Engel from Goethe University. HFC-23 primarily occurs as an unwanted by-product in the manufacture of the refrigerant HCFC-22. 

In 2015 India and China, which are considered the main emitters, announced ambitious plans to abate their factory emissions and in 2017 they reported that almost no more HFC-23 was being vented to the atmosphere. This would mean that emissions of this greenhouse gas into the atmosphere between 2015 and 2017 ought to have shown a 90 percent reduction. However, as the international team now reports, emissions have risen further and in 2018 reached an all-time high. 

The reduction of HFCs is part of the Kigali Amendment to the Montreal Protocol agreed in 2016. It entered into force in January 2020. Although China and India have not ratified the Amendment, by their own account they had achieved a massive reduction in emissions. “Our study indicates that China has not managed to reduce HFC-23 as reported," concludes Dr Kieran Stanley, who conducted the measurements at the University of Bristol in the framework of the international AGAGE measurement network. Additional measurements will show whether India has successfully implemented its abatement programme. 

“This is not the first time there's been controversy about HFC-23 emissions," says Kieran Stanley ruefully. With the United Nations Framework Convention on Climate Change, between 2005 and 2010 the industrial nations created incentives for emerging countries to reduce their emissions. Although emissions of this hazardous greenhouse gas did indeed decrease during that period, the system backfired: Manufacturers did not optimize their processes but instead produced more harmful by-products in order to pocket more funds for destroying them.

The Institute for Atmospheric and Environmental Sciences at Goethe University, where Kieran Stanley is now working as a postdoctoral researcher, has measured a large number of halogenated trace gases at its Kleiner Feldberg measuring station at regular intervals since 2013. Since recently, these measurements are part of the AGAGE network.

Publication: K. Stanley, D. Say, J. Mühle, C. Harth, P. Krummel, D. Young, S. O'Doherty, P. Salameh, P. Simmonds, R. Weiss, R. Prinn, P. Fraser and M. Rigby: Increase in global emissions of HFC-23 despite near-total expected reductions, in Nature Communications, https://doi.org/10.1038/s41467-019-13899-4 

Further information: Dr Kieran Stanley, Institute for Atmospheric and Environmental Sciences, Riedberg Campus, Tel.: +49(0)69-798-40249; stanley@iau.uni-frankfurt.de

FRANKFURT. Whether a sick cell dies, divides, or travels through the body is regulated by a sophisticated interplay of signal molecules and receptors on the cell membrane. One of the most important molecular cues in the immune system is Tumour Necrosis Factor α (TNFα). Now, for the first time, researchers from Goethe University have visualised the molecular organisation of individual TNFα receptor molecules and the binding of TNFα to the cell membrane in cells using optical microscopy.

Before TNFα can bind to a membrane receptor, the TNFR receptor must first be activated. By doing so, the key will only fit the lock under certain circumstances and prevents, among other things, that a healthy cell dies from programmed cell death. “For TNFR1 in the membrane, the binding of TNFα is mediated through several cysteine-rich domains, or CRDs," explains Sjoerd van Wijk form the Institute for Experimental Cancer Research in Paediatrics and the Frankfurt Stiftung für Krebskranke Kinder at Goethe University.

In particular, CRD1 of the TNFR1 makes it possible for TNFα to “attach". Researchers already knew that TNFR1 molecules cluster in a fashion similar to a dance, in which two, three or more partners grasp hands – with the dimers, trimers or oligomers consisting of single TNFR1 molecules – in the case of TNFR1. This kind of “structural reorganization" also takes place when there is no TNFα present. “Despite the significance of TNFα for many diseases, including inflammation and cancer, the physiology and patterns of TNFR1 in the cell membrane still remain largely unknown up to now," says Sjoerd Van Wijk, explaining the starting point for his research.

In order to understand the processes in the cell membrane in detail, van Wijk approached Mike Heilemann from the Institute for Physical and Theoretical Chemistry at Goethe University. Using a combination of quantitative microscopy and single-molecule super-resolution microscopy that he developed, Heilemann can visualise individual protein complexes as well as their molecular organisation in cells. Together with Ivan Dikic (Institute for Biochemistry II) and Simone Fulda (Institute for Experimental Cancer Research in Paediatrics) from Goethe University, Harald Wajant from the University Hospital Würzburg and Darius Widera from University Reading/UK, they were able to observe the dance of the TNFα receptors. Financial support was provided by the Deutsche Forschungsgemeinschaft (DFG) through the Collaborative Research Centre 807 “Transport and Communication across Biological Membranes".

As the researchers report in the current issue of “Science Signalling", membrane TNFR1 receptors exist as monomers and dimers in the absence of TNFα. However, as soon as TNFα binds TNFR1, receptor trimers and oligomers are formed in the membrane. The researchers also found indications for mechanisms that determine cell fate independently of TNFα. These findings could be relevant for cancer or and inflammatory diseases such as rheumatoid arthritis. “It clearly opens new paths for developing novel therapeutic approaches," states van Wijk.

Publication: C. Karathanasis, J. Medler, F. Fricke, S. Smith, S. Malkusch, D. Widera, S. Fulda, H. Wajant, S. J. L. van Wijk, I. Dikic, M. Heilemann, Single-molecule imaging reveals the oligomeric state of functional TNFα-induced plasma membrane TNFR1 clusters in cells. Sci. Signal. 13, eaax5647 (2020). DOI: 10.1126/scisignal.aax5647

Further information: Dr Sjoerd van Wijk, Institute for Experimental Cancer Research in Paediatrics, Niederrad Campus, Tel.: +49 69 67866574, Email: s.wijk@kinderkrebsstiftung-frankfurt.de

Prof Mike Heilemann, Institute for Physical and Theoretical Chemistry, Riedberg Campus, Tel.: +49 69 798 29424, Email: heileman@chemie.uni-frankfurt.de

FRANKFURT. Cows can adapt themselves to a fluctuating sodium content in their feed. How they do that was so far a secret. Researchers from Goethe University have now discovered a bacterium in the microbiome of the rumen which has a new type of cell respiration.

The cow can only process grass in its rumen with the help of billions of microorganisms. An entire zoo of bacteria, archaea and protozoa works there like on a production line: First of all, these single-cell organisms break down the cellulose, a polysaccharide. Other bacteria ferment the sugars released into fatty acids, alcohols and gases, such as hydrogen and carbon dioxide. Finally, methanogenic archaea transform these two gases into methane. 

An average cow produces about 110 liters of methane per day. It escapes from its mouth through rumination, but also mixes again with partly digested food. As a result, the sodium content of the grass pulp can fluctuate to a considerable degree (between 60 and 800 millimoles of sodium chloride (NaCLl) per liter).

A German-American research team has now discovered how the ruminal bacteria adapt to these extreme fluctuations in sodium content: “Bioinformatic analyses of the genome of ruminal bacteria led our American colleague Tim Hackmann to assume that some ruminal bacteria have two different respiratory circuits. One of them functions with sodium ions and the other without," explains Professor Volker Müller from the Department of Molecular Microbiology and Bioenergetics at Goethe University. That is why Müller suggested to his doctoral researcher Marie Schölmerich that she study a typical representative in the microbiome of ruminants: the bacterium Pseudobutyrivibrio ruminis.

Together with undergraduate student Judith Dönig and Master's student Alexander Katsyv, Marie Schölmerich cultivated the bacterium. Indeed, they were able to corroborate both respiratory circuits. As the researchers report in the current issue of the Proceedings of the National Academy of Sciences (PNAS), the electron carrier ferredoxin (Fd) is reduced during sugar oxidation. Reduced ferredoxin drives both respiratory circuits.

The one respiratory circuit comprises the enzyme complex Fd:NAD oxidoreductase (Rnf complex). It uses energy to transport sodium ions out of the cell. When they re-enter the cell, the sodium ions trigger an ATP synthase, so that ATP is produced. This respiratory circuit only works in the presence of sodium ions.
In the absence of sodium ions, the bacterium forms an alternative respiratory circuit with another enzyme complex: The Ech hydrogenase (synonymous: Fd:H+ oxidoreductase) produces hydrogen and pumps protons out of the cell. If these re-enter the cell via a second ATP synthase that accepts protons but not sodium ions, ATP is also produced.

“This is the first bacterium so far in which these two simple, completely different respiratory circuits have been corroborated, but our bioinformatic analyses suggest that they are also found in other bacteria," explains Marie Schölmerich. “It seems, therefore, that this adaptation strategy is more widespread," she assumes.

Interestingly, both enzyme complexes (Rnf and Ech) were also discovered in bacteria which are old in terms of evolutionary biology. Professor Müller's research group has examined them in depth, but always only found one of the two enzyme complexes and never both together. “We're now going to use synthetic microbiology methods to produce hybrids of bacteria that contain both complexes in order to optimize them for biotechnological processes. In this way, we can raise the cellular ATP content, which will make it possible to produce products of a higher quality," explains Professor Müller. The intention is to use the respiratory circuits to recover valuable substances through the fermentation of synthesis gas. This is the subject of the trials being conducted in the framework of a project sponsored by the Federal Ministry of Education and Research.

A picture can be downloaded under: https://www.muk.uni-frankfurt.de/84412971?

Caption: The bacterium Pseudobutyrivibrio ruminis (green), a typical ruminal bacterium, obtains energy via two different respiratory circuits. The one requires sodium ions, the other hydrogen ions (H+). In this way, it can adapt to fluctuating sodium concentrations in animal feed in an optimum way.

Picture: Goethe University/ Cow: Shutterstock

Publication: Schölmerich, M.C., Katsyv, A., Dönig, J., Hackmann, T., Müller, V. (20XX). Energy conservation involving two respiratory circuits. Proc. Natl. Acad. Sci. U.S.A., in press.

Further information: Professor Volker Müller, Molecular Microbiology and Bioenergetics, Riedberg Campus, Tel.: +49(0)69-798-29507; VMueller@bio.uni-frankfurt.de.

FRANKFURT. Determining the structure of large biomolecules is critical to many innovations in the fields of health, environment and sustainable technologies. Because structural research requires expensive equipment such as NMR spectrometers, the European Union funds research infrastructure. Beginning in February 2020, an additional € 10 million will be invested in the project iNEXT Discovery. The Centre for Biomolecular Magnetic Resonance (BMRZ) at Goethe University is a part of the project once again.

Currently, the iNEXT Collaboration is made up of 23 partners from 14 European countries. It is the first research infrastructure project combining different structural biological methods: X-ray spectroscopy, nuclear magnetic resonance spectroscopy (NMR), electron microscopy and biophysical methods. These methods make it possible to decode the three-dimensional structure of biological macromolecules in order to understand their function within the complex machinery of life. The goal is to develop new medicines, improved vaccinations, new biomaterials, biofuels, and enzymes for food production.

BMRZ at Goethe University makes its expertise in NMR spectroscopy available to researchers throughout Europe. Visitors from other countries already use the equipment daily to determine the structures of proteins, RNA and DNA. It is furthermore possible for industrial partners to participate via cooperation contracts in order, for example, to search specifically for active substances. Training programmes will be set up in the next four years for researchers with little previous experience with NMR.

“At BMRZ, we give European scientists access to the currently most powerful NMR technologies. In the next funding period, a 1.2 gigahertz NMR spectrometer will be available," says Professor Harald Schwalbe, Board Member of iNEXT-Discovery. “From 2020 onwards, we expect that 20 user groups annually will come from all over Europe to use our equipment and profit from our experience. In this way, we are all contributing to exciting science."

Further information: Professor Harald Schwalbe, BMRZ,  Institute for Organic Chemistry and Chemical Biology, Tel.: +49-69-798-29737; Email: schwalbe@nmr.uni-frankfurt.de

FRANKFURT. Dr Tobias Freimüller, Deputy Director of the Fritz Bauer Institute at Goethe University has been awarded the 2019 Rosl and Paul Arnsberg Prize from the Polytechnic Foundation of Frankfurt am Main. The award, which is given every three years, recognizes outstanding research on the history of Jewish citizens in Frankfurt.

 Tobias Freimüller received the prize for his 2019 study on the history of Jewish life in Frankfurt after 1945, which was the thesis of his postdoctoral qualification in the Faculty of Philosophy and History at Goethe University. The book will be published in the spring of 2020 with the title “Frankfurt und die Juden. Neuanfänge und Fremdheitserfahrungen 1945-1990“ (Frankfurt and Jews: New Beginnings and Experiences of Alienation 1945-1990), as the first volume of the series “Studien zur Geschichte und Wirkung des Holocaust“ (Studies on the History and Impact of the Holocaust) by Wallstein-Verlag.

“The work paints a highly differentiated picture of the complex relationships of Jews among themselves and with non-Jewish German society after the Shoah," said the jury, chaired by Professor Mirjam Wenzel, Director of the Jewish Museum and honorary professor at Goethe University, in praise of the winner. Freimüller's work, furthermore, has the potential of becoming a standard work.

Before 1933, Frankfurt am Main had the largest percentage of Jewish citizens in Germany, and its Jewish community was the second largest in Germany following Berlin. In finance, education, science, and through numerous associations and foundations, Jewish citizens influenced the city of Frankfurt in a distinct way. At the end of the war in the spring of 1945, the persecution, deportation and murder of Jews had completely destroyed this diverse culture. Had there once been almost 30,000 Jewish citizens in Frankfurt, now only 100 to 200 remained in the destroyed city.

A larger number of Jewish “Displaced Persons“ (DP) joined the few survivors who had quickly re-founded the Jewish community after the war. These DPs were refugees from Eastern Europe who saw in the American Headquarters in Frankfurt a gateway to their future lives. From here, they hoped to be able to travel to America, Palestine or other countries. But since this path was barred for the time being, thousands of Jewish DPs lived for several years in a hurriedly set-up camp in Frankfurt-Zeilsheim. At the same time, the first Frankfurt Jewish survivors began to return from exile, having been expressly encouraged to do so by Frankfurt's Mayor Walter Kolb.

In his study, Tobias Freimüller depicts how institutions and a social place for Jewish life were gradually able to be established in Frankfurt in the following years. On the one hand, the city serves as a typical example of Jewish post-war history in the Federal Republic of Germany, as a place where the conflict situations of Jewish post-war history can be seen under a magnifying glass. But Frankfurt was also an exception. Under the protection of the American occupying forces, a network of Jewish institutions was quick to form, later including an intellectual scene whose lighthouse was the Institute for Social Research, which had returned from exile. Nonetheless, the relationship between Jewish and non-Jewish citizens in Frankfurt remained particularly conflictive. Highlights of these disputes were the sensational blockade of the premiere of the play "Der Müll, die Stadt und der Tod" by Rainer Werner Fassbinder by the Jewish community in autumn 1985, and the Börneplatz conflict in 1987.

Where, after the end of National Socialism, and in what form did a memory of local Judaism still exist that could be taken up? How should Jewish places of memory that still existed in the city's topography be handled? How did the integration of the Holocaust survivors who fled Eastern Europe after the end of the war succeed, and why did the "second generation" of Jews since the 1960s articulate themselves so clearly in Frankfurt in particular? German-Jewish post-war history appears in the example of Frankfurt as a multi-faceted history of migration, conflict, and new intellectual beginnings, out of which a new Jewish consciousness ultimately developed in the 1980s.

The Rosl and Paul Arnsberg Prize from the Polytechnic Foundation of Frankfurt am Main was created in 2008 and has now been awarded for the sixth time. It is advertised internationally, and is dedicated to outstanding research on the history of Jewish life in Frankfurt. The prize is endowed with € 10,000.

Pictures may be downloaded here: http://www.uni-frankfurt.de/84238080www.uni-frankfurt.de/84238080

Caption: Tobias Freimüller was awarded the Rosl and Paul Arnsberg Prize from the Polytechnic Foundation of Frankfurt am Main for his work on the history of Frankfurt Judaism. (Credit: Polytechnic Foundation of Frankfurt am Main/Dominik Buschardt)

Further information: Dr Tobias Freimüller, Deputy Director of the Fritz Bauer Institute, Goethe University An-Institut, Westend Campus, Tel- +49 69/798 322-31, E-Mail freimueller@em.uni-frankfurt.de, Homepage www.fritz-bauer-institut.de