Awards for Researchers at the University of Bonn

Junior Research Group Leader

Dr. Markus Prim
Physikalisches Institut
Nussallee 12
53115 Bonn

Summary

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Junior Research Group Leader

Jun.-Prof. Dr. Tim Rollenske
Institute of Molecular Medicine and experimental Immunology
Biomedical Center II (BMZ-II)
Venusberg Campus 1
53127 Bonn

Summary

At birth, the intestine is colonized by commensal microbes which will form a relatively stable personal microbial community impacting almost any aspect of our health. Microbial colonization elicits intestinal antibody responses that are dominated by Immunoglobulin A (IgA), the most abundant antibody isotype at mucosal surfaces in mammals. In general, protective antibody responses are well-studied in context of infection, however, how antibodies at mucosal surfaces aid to establish host-microbial mutualism and keep homeostasis between the host and its microbiota is poorly understood. By combining gnotobiotic techniques with single B cell receptor repertoire sequencing, monoclonal antibody generation and testing and a variety of other immunological methods, we address three major research questions in the field of IgA biology in IgA-select: i) if the intestinal antibody response is prone to select functional bacteria cross-reactive IgA, ii) how luminal secretory (S)IgA modulates the intestinal antibody response, and iii) if the selective pressure opposed by antigen-specific SIgA on the bacteria leads to immune evasion of the microbiota long-term. To be able to address these research questions at molecular and mechanistic detail, we use different reductionist approaches which are based on newly designed mouse model systems of limited bacteria-reactive antibody specificities and the capability to work under hygiene conditions of defined reduced microbiota diversity. Further, if appropriate, we select bacterial model strains which are not only common members of the human microbiota but also opportunistic pathogens. The generated monoclonal antibodies that are characterized in our studies have therefore the potential to be used as pre-emptive therapy or treatment option in human infections. Overall, understanding the effects of SIgA on the microbiota’s physiology and stability is important to understand biological in vivo mechanisms in health and may allow manipulation of the microbiota to promote health. Further, the modulation of the host immune response by SIgA may enable and improve mucosal vaccination strategies which is a desirable goal for all vaccines targeting pathogens that primarily infect mucosal sites.

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Junior Research Group Leader

Dr. Barbara Verfürth
Institute for Numerical Simulation
Friedrich-Hirzebruch-Allee 7
53115 Bonn

Summary

Metamaterials are modern, artificially constructed materials that are tailored to exhibit new, astonishing physical properties. Therefore, they play a decisive role to control and manipulate waves, for instance in laser applications. Metamaterials are characterized by fine structures of different material components. The typical length of these fine structures is much smaller than the length of the whole material bulk. Further important building blocks in applications are nonlinear material responses and time modulation. Finally, the robustness of the material properties with respect to imperfections in the fabrication process is highly relevant. Within mathematical models, these applications lead to partial differential equations with a coexistence of multiple temporal and spatial scales, nonlinearities, and random perturbations. Numerical simulations have very high potential in the material design as they can replace time-consuming and costly experiments. Yet, standard numerical methods need to resolve all fine material structures so that their computational effort is prohibitive even with today's computer resources. In contrast, computational multiscale methods (CMMs) deliver a macroscopic representation of the solution by suitable local upscaling processes. However, the incorporation of nonlinearities, random perturbations, and multiscale dynamics require new computational paradigms for several reasons. Firstly, CMMs often rely on linear arguments that break down for nonlinear problems. Thus, most approaches propose to couple nonlinear problems on fine and macroscopic scales in a rather complicated manner. Secondly, Monte Carlo techniques require many multiscale simulations with new, rather costly upscaling processes for each random sample. Present approaches at least for the numerical analysis additionally rely on stochastic homogenisation results. Thirdly, CMMs for dynamical problems mostly treat multiple spatial or multiple temporal scales exclusively.In this project, we develop and analyse novel CMMs to tackle nonlinear, randomly perturbed, and dynamical problems. The main goals are connected to fundamental mathematical and computational challenges requiring a revolutionary coalescence of multiscale methods, model reduction, uncertainty quantification, and time integration. We (a) explore adaptive linearised and nonlinear approximation spaces for nonlinear multiscale problems, (b) unite multiscale methods and Monte Carlo approaches for randomly perturbed problems, and (c) bridge spatial and temporal multiscale methods for rapid multiscale dynamics. While the general nature of our approaches allows their application to a wide range of problems, we put special emphasis on wave-related phenomena. Moreover, we rigorously justify all methods by error estimates which is crucial beyond the experimentally validated regime. Ultimately, this project will push forward the frontiers of CMMs for realistic (metamaterial) applications.

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Junior Research Group Leader

Dr. Hanno Kruse
Institut für Politische Wissenschaft und Soziologie
Lennéstraße 25
53113 Bonn

Summary

How does school sorting affect local peer processes among students that shape their emerging collective identities, social networks, and academic self-concepts? The proposed project offers a new perspective on this issue by focusing on local school administrators and their consequential decisions on school admissions and classroom placements. Schools are key sites of social exchange whose impact goes well beyond individual life courses. Local peer processes in schools affect societal cohesion in general, as they often produce substantial disparities along the lines of ethnicity, gender, and social class. Sociological research has established the importance of compositional features of schools for peer processes among adolescents. However, what is missing are data and research designs that allow one to identify the effects of sorting decisions (i.e., school admissions and class placements) on peer processes. By closing this gap, the planned project seeks practically relevant insights. Better knowledge on the social consequences of sorting decisions is urgently needed – all the more since the COVID 19 pandemic has put the organisation of schools directly to the test.The proposed project builds on the notion that headmasters and teachers have a much greater influence on local peer processes at their schools than they are currently aware of. Besides aiming for balanced class compositions, this project highlights that headmasters and teachers can affect the extent to which different demographic categories align or crosscut each other – an often-overlooked compositional feature with profound social consequences. The project will combine structuralist perspectives on school sorting with analyses of everyday peer processes to formulate and test new hypotheses on how local school administrators can take deliberate sorting decisions in support of inclusive identities, cohesive networks, and positive academic self-concepts. Empirically, the proposed project will conduct a large-scale field experiment targeting headmasters and teachers in their sorting decisions. Focusing on schools in small and mid-sized districts in Germany, the project will provide nationally representative information on a population that is little noticed though considerable in size. The field experiment will be accompanied by a longitudinal survey addressing local school administrators and students as well as by the collection of administrative data from local school authorities. In addition, and in preparation of the primary data collection, the project seeks to conduct secondary analyses of existing large-scale datasets. Combining these various data sources holds the potential for groundbreaking insights into the social impact of local school administrators and their sorting decisions. Doing so will contribute not only to a better general understanding of the social consequences of sorting but also to the design of effective practical interventions in German secondary schools.

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Junior Research Group Leader

Dr. Larissa K. S. von Krbek
Kekulé-Institute for Organic Chemistry and Biochemistry
Gerhard-Domagk-Str. 1
53121 Bonn

Summary

Most supramoleclar self-assembly processes are thermodynamically driven, i.e. energetically high components assemble into a thermodynamically more favourable structure. In contrast, natural systems predominantly operate far from equilibrium through the dissipation of energy — i.e. their assembly is driven by the consumption of a fuel, allowing for greater structural complexity, spatiotemporal control over function, self-healing, adaptivity, emergent behaviour, and the ability to perform work. Implementing such out-of-equilibrium (OOE) processes into synthetic systems will lead to greater complexity and function in man-made materials and will profoundly impact the fields of chemistry, material science, and synthetic biology. Furthermore, investigation of these man-made out-of-equilibrium systems might provide a better understanding of the kinetic and thermodynamic constraints in living systems. While the field of supramolecular chemistry has taken first steps towards realising dissipative self-assembly (DSA) of gels, polymers, and colloids, smaller supramolecular structures such as metallo-supramolecular cages are still lacking. The aim of this project is to design and investigate new metallo-supramolecular systems that assemble through the dissipation of energy, with the final goal of furthering our understanding of out-of-equilibrium systems and emergent behaviour. The first goal of this project is the synthesis and investigation of new mononuclear metal complexes that assemble far from the thermodynamic equilibrium by energy dissipation — either via a chemical fuel or a light. With a couple of these mononuclear model systems at hand, this project will move on to the second major aim, the challenging dissipative self-assembly of metallo-supramolecular cages. Self-assembly of three-dimensional cages adds a level of complexity to the systems, which makes them more suitable as model compounds to understand dissipative self-assembly in nature. The long-term goals of this project are using the previously established out-of-equilibrium systems to understand emergent behaviour in supramolecular chemistry and possibly in nature and utilise the dynamic behaviour of the out-of-equilibrium cages to tackle common drawbacks of conventional supramolecular chemistry, namely, gaining spatiotemporal control over guest release and circumventing product inhibition in supramolecular catalysis. Confinement of molecular systems into nanospaces (e.g. vesicles) can lead to unprecedented behaviour and possibly emergence.

Website⁵⁶⁶

Junior Research Group Leader

Prof. Dr. Yongguo Li
Institute of Pharmacology and Toxicology
Venusberg-Campus 1
53127 Bonn

Summary

Obesity develops when energy intake chronically exceeds energy expenditure. The capacity for thermogenic adipocytes (brown and brite/beige) to dissipate chemical energy therefore increasing energy expenditure offers great potential to combat obesity. With limited amount of human brown fat, increasing the relative abundance of brite cells in white fat (WAT browning) offers an opportunity to increase the mass of thermogenic brite adipose tissues and meanwhile decrease the amount of WAT, thereby turning an energy-storing organ into an energy-dissipating one. However, a comprehensive understanding of the regulatory mechanisms mediating WAT browning is still lacking. Variation in white fat browning propensity among inbred mouse strains provides a unique opportunity to zoom in on the core regulators of the browning program across different genotypes. In previous studies, combining comparative transcriptomics, perturbation-based assays and gene network analyses, I revealed novel regulators as well as a core regulatory network that contributes to brite adipogenesis. Although these results constitute the most comprehensive attempt to define the regulatory network underlying white fat browning, further efforts are needed to perform in-depth characterization of key factors, refine the organization of the network and draw a more complete canvas of the sources of gene expression variability in this system. Moreover, there is a more complex source of strain variation in browning propensity, exemplified by cis-driven between C57BL/6J and 129S6/SvEvTac, while trans-driven between C57BL/6J and FVB/NJ. My future work now aims at the systematic analyses of transcription factor binding, epigenetic state and gene expression to identify natural genetic variants that affect the browning capacity. Specifically, I hypothesize that distinct genetic variants affect DNA-binding of transcription factors, which lead to variable histone modifications and collectively influence gene expression and browning propensity (Objective A) and operating through highly connected cellular networks of genes targeting browning capacity (Objective B). Testing these hypotheses will lead to the discovery of novel functional regulatory elements, candidate genes, epigenetic basis and molecular networks underlying white fat browning. Combined with further extensive validation both in vitro and in vivo (Objective C) through gain- and loss-of-function experiments as well as simultaneous activation of multiple genes with the CRISPR–dCas9-activator system, an in-depth understanding of novel key transcription factor(s) as well as molecular networks in the control of browning capability will be obtained. Together, we aim to devise a comprehensive molecular network that regulates white fat browning. In the long run, a full understanding of the molecular architecture underlying brite cell recruitment could facilitate the development of therapeutic approaches for combating metabolic imbalance.

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Junior Research Group Leader

Dr. Peng Yu
Institut für Nutzpflanzenwissenschaften und Ressourcenschutz
Lehrstuhl für Crop Functional Genomics
Friedrich-Ebert-Allee 144
53113 Bonn

Summary

The rhizosphere is the narrow region of soil that is directly influenced by root secretions and that is associated soil microorganisms known as the root microbiome. The interaction of roots with their microbiome is instrumental for plant health and fitness. Understanding the molecular and genetic basis of these relationships will enable to sustain plants with superior performance on agricultural soils with poor nutrient availability and thus reducing mineral fertilizer application.The project will start with uncovering the complexity of host root interactions with the soil microbes by integration of transcriptome data of the root cortex and stele and rhizosphere microbiome genomic data obtained during root development. To this end a panel of genetically diverse inbred lines with contrasting nitrogen use efficiencies and root mutants with distinct developmental defects of lateral roots and root hairs under different nitrogen conditions in maize will be surveyed. Gene co-expression, microbial co-occurrence/co-abundance and trans-kingdom networks will identify the hub genes interacting with the keystone microbial OTUs (operational taxonomic units). Moreover, metabolic signal transmission from the endosphere to the rhizosphere will be determined by profiling of the metabolome from root exudates. Non-invasive root imaging by MRI (Magnetic Resonance Imaging), dynamics of carbon and nitrogen imaging by PET (Positron Emission Tomography) and NanoSIMS (Nanometer-scale Secondary Ion Mass Spectrometry) will further track the architectural and functional information of the root and its exudates across spatial compartments in the different zones of a single root and among different root types. In addition, spatial patterning of candidate hub genes and keystone microbes will be demonstrated by in situ hybridization and CARD-FISH (catalyzed reporter deposition combined with fluorescence in situ hybridization) experiments. Finally, the hub genes regulating the biosynthesis of secondary metabolites interacting with microbes will be knocked out by genome editing via CRISPR/Cas9 to generate new mutants. In parallel, representative keystone microbial OTUs will be isolated and cultured and derived synthetic communities will be employed to validate their potential roles on gene regulation in maize. In summary, the overall objective of this project is the mechanistic understanding of the function of root and rhizosphere microbes to enhance plant tolerance to nitrogen deficiency. This will pave the way for crop breeding applications and the application of microbial synthetic communities to secure future food production and sustain efficient resource usage in agriculture.

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Junior Research Group Leader

Dr. Katrin Jeannette Czogalla-Nitsche
Institut für Experimentelle Hämatologie und Transfusionsmedizin
Venusberg-Campus 1
53127 Bonn

Summary

Vitamin K is essential and reduced by the enzyme vitamin K 2,3-epoxide reductase complex 1 (VKORC1) to vitamin K hydroquinone (KH2) in vivo. KH2 is a co-factor of the enzyme gamma-glutamyl-carboxylase (GGCX) which gamma-carboxylates vitamin K dependent (VKD) proteins. This posttranslational modification is indispensable for biological activity of VKD proteins. Defects in the vitamin K metabolism are leading to bleedings due to under-carboxylated VKD clotting factors. Interestingly, mutations in GGCX result in additional phenotypes that are associated with skin, heart and bone/cartilage defects. Moreover, inhibition of VKORC1 by the oral anticoagulant warfarin induces vascular calcification and ER stress in vitro. Furthermore, we suggest a second vitamin K dependent pathway due to the isozyme of VKORC1, named VKORC1-like1 (VKORC1L1) that catalyzes the reduction of vitamin K as well. It was shown that VKORC1L1 has function in cellular antioxidation as well as in cholesterol, calcium and glucose metabolism.This research grant will investigate the function of vitamin K and the enzymes involved in the vitamin K cycle beyond the coagulation cascade. This will include experiments with induced pluripotent stem cells (iPSCs) and several mouse models. With iPSCs of patients harbouring a mutation in VKORC1 or GGCX it will be possible to investigate vitamin K deficiencies for the first time in the most native cell system to date. Due to the differentiation into hepatocytes (high expression of VKORC1 and GGCX), neurons (high expression of VKORC1L1) and smooth muscle cells (calcification model) we will examine the diverse phenotypes in the specific cell type. Furthermore, we will introduce fluorescent tags into iPSCs by CRISPR/Cas9 technology in order to detect VKOR proteins endogenously for the first time. This will allow to investigate how the enzymes are organized within cells and interact with respect to each other. Additionally, expression and regulation of the respective genes will be analyzed under different conditions, where we will induce ER stress and treat the cells with different oral anticoagulants. Another aim is the generation of different mouse models. We will introduce fluorescent tags as fusion proteins to VKORC1 or VKORC1L1 to identify cell type specific expression of the respective VKOR proteins. This is mandatory for the targeted generation of conditional VKORC1-/- mice. In addition, we will focus on the altered cholesterol, calcium and glucose metabolism in VKORC1L1-/- mice. In summary, this work will contribute to a better understanding of the vitamin K cycle especially with regard to its function in non-hepatic tissues, the interplay of the enzymes among each other and to patient-specific phenotypes.

Junior Research Group Leader

Prof. Dr. Sebastian Neubert
Helmholtz-Institut für Strahlen- und Kernphysik
Nußallee 14-16
53115 Bonn

Summary

The strong interaction is the least understood sector of the standard model of particle physics. In the last decade the discovery of exotic mesons, which cannot be explained as quark-antiquark states, has highlighted the rich structure of strongly interacting particles beyond the quark model. Recently two exotic baryons, decaying into a proton and a J/psi have been discovered at the LHCb experiment. These two resonances are compatible with an interpretation as five-quark states and are therefore referred to as pentaquarks. Here a program is proposed to investigate the nature of these exotic particles in detail by exploring new decay modes and searching for members of a pentaquark multiplet.

Website⁷

Junior Research Group Leader

Prof. Dr. Florian Bernlochner
Physikalisches Institut
Nußallee 12
53115 Bonn

Summary

Matter and interactions of elementary particles in nature are so far successfully described by the Standard Model of particle physics. Albeit this success of the Standard Model, a range of physical phenomena observed in nature cannot be explained and a prominent example is the overabundance of matter over anti-matter in the universe. At the end of the year 2018 the super flavour factory experiment Belle II will start to record large samples of B-meson decays. The precision study of B-mesons is interesting as their decay allows for measuring the size of Charge-Parity violation and thus probe the matter and anti-matter asymmetry in particle decays. The size of Charge-Parity violation cannot be determined by a single measurement, but by the combination of several precision observables and any disagreement would be a strong indication for new physics processes beyond the Standard Model. The goal of this proposal is to carry out a precision measurement of the CKM matrix element Vub, whose absolute value is one of the important constraints in the extraction of the size of Charge-Parity violation. Experimentally Vub can be measured by studying semileptonic B-meson decays obtained by studying exclusive or inclusive hadronic final states. There is a long-standing tension between both approaches with a statistical significance of 3.4 standard deviations. One possible reason for this tension is the use of model functions to describe the b-quark motion inside the B-meson in state-of-the-art determinations using inclusive decays. To eliminate this possibility, this application proposes a coherent strategy how this functional form can be extracted simultaneously with Vub in a global analysis of measured kinematic distributions of radiative and semileptonic B-meson decays measured with the Belle II experiment. As part of the preparatory work and to establish the necessary experimental techniques a first analysis using Belle data will be carried out. The direct experimental determination of the functional form of the b-quark motion inside the B-meson will remove the model assumptions made in the state-of-the-art inclusive Vub measurements which in turn will help to shed light on the observed differences between inclusive and exclusive Vub measurements. In addition the shape function can be used to search for new physics contributions in radiative decays in a model independent way.

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Jun.-Prof. Dr. Vera Traub
Research Institute for Discrete Mathematics
Lennéstr. 2
53113 Bonn

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Prof. Dr. Elvira Mass
LIMES-Institut
Carl-Troll-Str. 31
53115 Bonn

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Dr. Georg Oberdieck
Mathematisches Institut
Endenicher Allee 60
53115 Bonn

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Prof. Dr. Patrik Ferrari
Institut für Angewandte Mathematik
Endenicher Allee 60
53115 Bonn

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Prof. Dr. med. Natalija Novak
Klinik und Poliklinik für Dermatologie und Allergologie
Venusberg-Campus 1
53127 Bonn

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Prof. Dr. med. Christian Kubisch
Universitätsklinikum Hamburg-Eppendorf
Institut für Humangenetik
Martinistraße 52
20251 Hamburg

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Dr. Dominic Winter
Institut für Biochemie und Molekularbiologie

Nussallee 11
53115 Bonn

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Dr. Yingkun Li
Mathematisches Institut

Endenicher Allee 60
53115 Bonn

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Prof. Dr. Lisa Sauermann
Institute for Applied Mathematics

Endenicher Allee 60
53115 Bonn

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Dr. Max Crüsemann
Institute of pharmaceutical biology

Nußallee 6
53115 Bonn

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Dr. Illia Karabash
Institute for Applied Mathematics
Functional analysis

Endenicher Allee 60
53115 Bonn

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Prof. Dr. Paul Marx
Professor of Political Economy

Am Hof 1
53113 Bonn

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Prof. Dr.  Claudia Jacobi
Institut für Klassische und Romanische Philologie
Abteilung für Romanistik

Am Hof 1
53113 Bonn

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Prof. Dr. Stefan Feuser
Institut für Archäologie und Kulturanthropologie
Abteilung Klassische Archäologie

AVZ III, Römerstraße 164
53117 Bonn

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PD Dr. Alexander Ivanov
Mathematisches Institut
Endenicher Allee 60
53115 Bonn

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PD Dr. Andreas Schwab
Institut für Klassische und Romanische Philologie
Am Hof 1 e
53113 Bonn

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Dr. Christian Meierhofer
Abteilung Neuere deutsche Literaturwissenschaft
Am Hof 1d
53113 Bonn

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PD Dr. Christian Rode
Institut für Philosophie
Am Hof 1
53113 Bonn

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PD Dr. Simone Schultz-Balluff
Institut für Germanistik, Vergleichende Literatur- und Kulturwissenschaft
Am Hof 1d
53113 Bonn

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Prof. Dr. Philipp Sasse
Institut für Physiologie I
Nussallee 11
53115 Bonn

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Prof. Dr. Sandra Blaess
Institut für Rekonstruktive Neurobiologie
Venusberg-Campus 1
53127 Bonn

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