Researchers from Frankfurt produce tsetse attractants in yeast to contain sleeping sickness
FRANKFURT. Because the tsetse fly can transmit sleeping sickness, it is commonly combatted with insecticides or caught in traps. Bioscientists at Goethe University have now developed a method for producing the attractants for the traps in a biotechnological procedure. The Frankfurt scientists hope that in the future, the attractants can then be produced locally in rural areas of Africa at low cost (Scientific Reports, DOI: 10.1038/s41598-020-66997-5).
The tsetse fly occurs in large regions of sub-Saharan
Africa. The flies feed on human and animal blood, transmitting trypanosoma in
the process – small, single-cell organisms that use the flies as intermediate
host and cause a dangerous inflammation of the lymph and nervous system in both
animals and humans. There is no vaccination for this sleeping sickness;
untreated, it usually ends in death. In agriculture, particularly cattle
breeding, sleeping sickness – or trypanosomiasis – causes enormous damages in
the form of sick and dead animals.
In addition to the use of insecticides, the insects are also caught in traps. The attractants used include substances that also occur in cattle urine and which attract tsetse flies. These substances (3-ethylphenol and 3-propylphenol, or 3-EP and 3-PP for short) are synthesized out of oil derivatives or also extracts from cashew nut shells through chemical processes. However, both processes are complex and neither practical nor affordable for rural communities in Africa.
In the LOEWE collaborative research project MegaSyn, molecular biologists at Goethe University have now succeeded in producing 3-EP and 3-PP in genetically modified brewer’s yeast (Saccharomyces cerevisiae). They used a yeast strain into which they had previously introduced a new metabolic pathway, and changed its sugar metabolism. This enabled the yeasts to produce similarly high concentrations of 3-EP and 3-PP as those which occur in cow urine.
Doctoral student Julia Hitschler from the Institute for Molecular Biosciences at Goethe University explains: “Our yeasts could ideally grow in Africa in nutrient solutions on the basis of plant waste products, food rests or fodder rests. This would make production of the attractant almost cost-free. We are currently looking for partners to help us test our yeasts locally and provide them to the local population.”
The potential for the new yeasts go beyond the tsetse attractants, add Professor Eckhard Boles, who heads the project. In the future, other substances that have been previously won through oil or coal could be produced through the new yeasts: “Our yeasts could be developed to produce other alkylphenols besides 3-EP and 3-PP. These alkylphenols could be used for the production of lubricant additives or surface-active substances in cleaning agents.”
Publication: Julia Hitschler, Martin Grininger, Eckhard Boles: Substrate promiscuity of polyketide synthase enables production of tsetse fly attractants 3-ethylphenol and 3-propylphenol by engineering precursor supply in yeast. Scientific Reports, https://doi.org/10.1038/s41598-020-66997-5
A game theoretical study shows that envy coupled with competition divides society into an upper and lower class
FRANKFURT. Can class differences come about endogenously, i.e. independent of birth and education? Professor Claudius Gros from the Institute for Theoretical Physics at Goethe University pursued this issue in a game theoretical study. He was able to show that the basic human need to compare oneself with others may be the root cause of the formation of social classes.
It's generally recognized that differences in background and education cement class differences. It is less clear when and under what circumstances individual psychological forces can drive an initially homogenous social group apart and ultimately divide it. Claudius Gros, professor for theoretical physics at Goethe University, investigated this question in a mathematical precise way using game theory methods. “In the study, societies of agents – acting individuals – are simulated within game theory, which means that everybody optimises her/his success according to predetermined rules. I wanted to find out whether social differences can emerge on their own if no one starts off with advantages – that is, when all actors have the same skills and opportunity," the physicist explains.
The study is based on the assumption that there are things in every society that are coveted but limited – such as jobs, social contacts and positions of power. An inequality is created if the top position is already occupied and someone must therefore accept the second-best job – but not, however, a societal division. With the help of mathematical calculations Gros was able to demonstrate that envy, which arises from the need to compare oneself with others, alters individual behaviour and consequently the agents' strategies in characteristic ways. As a result of this changed behaviour, two strictly separate social classes arise.
Game theory provides the mathematical tools necessary for the modelling of decision situations with several participants, as in Gros' study. In general, constellations in which the decision strategies of the individual actors mutually influence each other are particularly revealing. The success of the individual depends then not only on his or her own actions, but on others' actions as well, which is typical of both economic and social contexts. Game theory is consequently firmly anchored in the economy. The stability condition of game theory, the “Nash equilibrium", is a concept developed by John Forbes Nash in his dissertation in 1950, using the example of poker players. It states that in equilibrium no player has anything to gain by changing their strategy if the other players do not change theirs either. An individual only tries out new behaviour patterns if there is a potential gain. Since this causal chain also applies to evolutionary processes, the evolutionary and behavioural sciences regularly fall back on game theoretical models, for example when researching animal behaviours such as the migratory flight routes of birds, or their competition for nesting sites.
Even in an envy-induced class society there is no incentive for an individual to change his or her strategy, according to Gros. It is therefore Nash stable. In the divided envy society there is a marked difference in income between the upper and lower class which is the same for all members of each social class. Typical for the members of the lower class is, according to Gros, that they spend their time on a series of different activities, something game theory terms a “mixed strategy". Members of the upper class, however, concentrate on a single task, i.e., they pursue a “pure strategy". It is also striking that the upper class can choose between various options while the lower class only has access to a single mixed strategy. “The upper class is therefore individualistic, while agents in the lower class are lost in the crowd, so to speak," the physicist sums up.
In Claudius Gros' model, whether an agent lands in the upper or lower class is ultimately a matter of coincidence. It is decided by the dynamics of competition, and not by origin. For his study, Gros developed a new game theoretical model, the “shopping trouble model" and worked out a precise analytical solution. From it, he derives that an envy-induced class society possesses characteristics that are deemed universal in the theory of complex systems. The result is that the class society is beyond political control to a certain degree. Political decision-makers lose a portion of their options for control when society spontaneously splits into social classes. In addition, Gros' model demonstrates that envy has a stronger effect when the competition for limited resources is stronger. “This game theoretical insight could be of central significance. Even an 'ideal society' cannot be stably maintained in the long term – which ultimately makes the striving for a communistic society seem unrealistic," the scientist remarks.
Publication: Claudius Gros, „Self induced class stratification in competitive societies of agents: Nash stability in the presence of envy“, Royal Society Open Science , Vol 7, 200411 (2020).
Further information: Professor Claudius Gros, Institute for Theoretical Physics, Riedberg Campus, E-Mail firstname.lastname@example.org
Frankfurt researchers deliver experimental proof for a 90 year-old theory
FRANKFURT. Light exerts a certain amount of pressure onto a body: sun sails could thus power space probes in the future. However, when light particles (photons) hit an individual molecule and knock out an electron, the molecule flies toward the light source. Atomic physicists at Goethe University have now observed this for the first time, confirming a 90 year-old theory.
early as the 16th century, the great scholar Johannes Kepler
postulated that sunlight exerted a certain pressure, as the tail of the comets
he observed consistently pointed away from the sun. In 2010 the Japanese space
probe Ikaros used a sun sail for the first time in order to use the power of
sunlight to gain a little speed.
Physically and intuitively, the pressure of light or radiation can be explained by the particle characteristic of light: light particles (photons) strike the atoms of a body and transfer a portion of their own momentum (mass times speed) onto that body, which thus becomes faster.
However, when in the 20th century physicists studied this momentum transfer in the laboratory during experiments on photons of certain wavelengths which knocked individual electrons out of atoms, they were met by a surprising phenomenon: the momentum of the ejected electron was greater than that of the photon that struck it. This is actually impossible – since Isaac Newton it has been known that within a system, for every force there must exist an equal but opposite force: the recoil, so to speak. For this reason, the Munich scientist Arnold Sommerfeld concluded in 1930 that the additional momentum of the ejected electron must come from the atom it left. This atom must fly in the opposite direction; in other words, toward the light source. However, this was impossible to measure with the instruments available at that time.
Ninety years later the physicists in the team of doctoral student Sven Grundmann and Professor Reinhard Dörner from the Institute for Nuclear Physics have succeeded for the first time in measuring this effect using the COLTRIMS reaction microscope developed at Goethe University Frankfurt. To do so, they used X-rays at the accelerators DESY in Hamburg and ESRF in French Grenoble, in order to knock electrons out of helium and nitrogen molecules. They selected conditions that would require only one photon per electron. In the COLTRIMS reaction microscope, they were able to determine the momentum of the ejected electrons and the charged helium and nitrogen atoms – which are called ions – with unprecedented precision.
Professor Reinhard Dörner explains: “We were not only able to measure the ion’s momentum, but also see where it came from – namely, from the recoil of the ejected electron. If photons in these collision experiments have low energy, the photon momentum can be neglected for theoretical modelling. With high photon energies, however, this leads to imprecision. In our experiments, we have now succeeded in determining the energy threshold for when the photon momentum may no longer be neglected. Our experimental breakthrough allows us to now pose many more questions, such as what changes when the energy is distributed between two or more photons.”
Publication: Sven Grundmann, Max Kircher, Isabel Vela-Perez, Giammarco Nalin, Daniel Trabert, Nils Anders, Niklas Melzer, Jonas Rist, Andreas Pier, Nico Strenger, Juliane Siebert, Philipp V. Demekhin, Lothar Ph. H. Schmidt, Florian Trinter, Markus S. Schöffler, Till Jahnke, and Reinhard Dörner: Observation of Photoion Backward Emission in Photoionization of He and N2. Phys. Rev. Lett. 124, 233201 https://doi.org/10.1103/PhysRevLett.124.233201
Goethe University physicists develop free covid-19 analysis website to compare the number of cases and deaths by country
FRANKFURT. There is no lack of data on global corona developments. But if you want to actively compare countries yourself and relate case and death figures across countries, you can now get a quick overview with just a few clicks – and gain surprising insights in the process.
The new web service “Goethe Interactive
Covid-19 Analyzer“ which Fabian Schubert in the working group for the theory of
complex systems at the Institute for Theoretical Physics developed alongside
his dissertation is simple to use: go to the “Goethe Interactive Covid-19
Analyzer” website, click on the countries and number of cases in questions, and
drag the curves over each other. Congruent? The answer is immediately visible.
In the same way – depending on the individual question - the daily number of
cases or deaths, or the total number of infected or deceased individuals can be
compared. The underlying data for countries from “A” as in Afghanistan through
“Z” as in Zimbabwe is provided by the known covid-19 databases of the European Centre
for Disease Control” and the “Johns HopkinsCenter For Systems Science and Engineering.”
“Our interactive tool allows researchers, journalists and other interested parties to quickly gain an overview of outbreak developments,” explains Professor Claudius Gros, who studies the modelling of covid-19 outbreaks himself at the Institute for Theoretical Physics, and who as Schubert’s doctoral advisor encouraged him to develop the service tool. Those who use the tool may also discover relationships that provide inspiration for additional research on epidemic processes.
Gros, for example, was surprised that the scaled trajectory curves of the case numbers from Germany and Spain “are almost identical, although the two countries pursued significantly different lockdown measures.” There are also interesting clues regarding the unexplained issue of the number of unrecorded cases of corona infections. For Italy, the scaled curve of covid-19 infections corresponds to the curve of corona deaths if the daily case numbers are applied to the total numbers of the sick or the deceased. “This indicates that the unrecorded case numbers may not have changed significantly over the course of the outbreak – even though testing increased.”
The “Goethe Interactive Covid-19 Analyzer” from the Institute for Theoretical Physics offers numerous options for combining data per mouse click. “The page has only been live for a couple of days,” says Gros. It therefore remains to be seen how many researchers and other interested parties will use the new analytical tool. The first scientists have already indicated interest, however. And the theoretical physicist is certain: “The website is certainly useful for the final papers and doctoral dissertations on covid-19 that will soon be written. And also for secondary school students who want to present a paper on corona.”
The new analytic tool is hosted on the webserver of the Institute for Theoretical Physics, which is also providing the necessary technical support.
Website: Goethe Interactive Covid-19 Analyzer: https://itp.uni-frankfurt.de/covid-19
Publication: Claudius Gros, Roser Valenti, Kilian Valenti, Daniel Gros, Strategies for controlling the medical and socio-economic costs of the Corona pandemic (2020); https://arxiv.org/abs/2004.00493
Further information: Prof. Dr. Claudius Gros, Institut für Theoretische Physik, Campus Riedberg, E-Mail email@example.com
Frankfurt researchers use ecological niche modelling to project the distribution of Chagas disease vectors
FRANKFURT. An infection with Chagas disease is only possible in Latin America since the insect species that spread the disease only occur there. Scientists at Goethe University and the Senckenberg Society for Natural Research have now used ecological niche models to calculate the extent to which habitats outside of the Americas may also be suitable for the bugs. The result: climatically suitable conditions can be found in southern Europe for two kissing bug species; along the coasts of Africa and Southeast Asia the conditions are suitable for yet another species. The Frankfurt scientists therefore call for careful monitoring of the current distribution of triatomine bugs. (eLife DOI: 10.7554/eLife.52072)
The acute phase of the tropical Chagas disease
(American Trypanosomiasis) is usually symptom-free: only in every third case
does the infecting parasite (Trypanosoma
cruzi) cause any symptoms at all, and these are often unspecific, such as
fever, hives and swollen lymph glands. But the parasites remain in the
body, and many years later chronic
Chagas disease can become life-threatening with pathological enlargement of the
heart and progressive paralysis of the gastrointestinal tract. There is no
vaccine for Chagas disease. The WHO estimates that 6 to 7 million people are
infected worldwide, with the majority living in Latin America (about 4.6
million), followed by the USA with more than 300,000 and Europe with approximately
80,000 infected people.
Chagas parasites are transmitted by predatory blood-sucking bugs that ingest the pathogen along with the blood. After a development period in the intestinal tract of the bugs, the parasites are shed in the bug's faeces. The highly infectious faeces are unintentionally rubbed into the wound by the extreme itching caused by the bug bite. Oral transmission by eating food contaminated with triatomine bug faeces is also possible.
Researchers led by the Frankfurt parasitologists and infection biologists Fanny Eberhard and Professor Sven Klimpel have used niche models to investigate which climatic conditions in the world are suitable for Latin American kissing bugs. In particular, temperature and precipitation patterns were incorporated into the calculations on the climatic suitability of a region. The researchers were able to show that currently in addition to Latin America, Central Africa and Southeast Asia also have suitable habitats for triatomines. Two of the triatomine species, Triatoma sordida and Triatoma infestans, are now finding suitable habitats in temperate regions of southern Europe such as Portugal, Spain, France and Italy. Both triatomine species frequently transmit the dangerous parasites in Latin America and can be found inside or near houses and stables, where they get their nightly blood meals preferably from dogs, chickens and humans.
Another triatomine species, Triatoma rubrofasciata, has already been detected outside Latin America. The model calculations by the Frankfurt scientists identify suitable habitats along large areas of the African and Southeast Asian coasts.
Professor Sven Kimpel explains: “There are people living in Europe who were infected with Chagas in Latin America and are unknowingly carriers of Trypanosoma cruzi. However, the parasite can currently only be transmitted to other people through untested blood preservations or by a mother to her unborn child. Otherwise, Trypanosoma cruzi requires triatomine bugs as intermediate hosts. And these bugs are increasingly finding suitable climatic conditions outside Latin America. Based on our data, monitoring programmes on the distribution and spreading of triatomine bugs would therefore be feasible. Mandatory reporting of Chagas disease cases could also be helpful."
Publication: Fanny E. Eberhard, Sarah Cunze, Judith Kochmann, Sven Klimpel. Modelling the climatic suitability of Chagas disease vectors on a global scale. eLife 2020;9:e52072 doi: 10.7554/eLife.52072, https://elifesciences.org/articles/52072
An image may be downloaded here: http://www.uni-frankfurt.de/88953890
Caption: The triatomine or “kissing" bug Triatoma infestans. Credit: Dorian D. Dörge for Goethe University Frankfurt
Prof. Dr. Sven Klimpel
Institute for Ecology, Evolution and Diversity, Goethe University
& Senckenberg Biodiversity and Climate Research Centre
Tel. +49 69 798 42237