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JLUpub ist das institutionelle Repositorium der Justus-Liebig-Universität.
JLUpub bietet Mitgliedern und Angehörigen der Universität die Möglichkeit neben wissenschaftlichen Dokumenten auch Forschungsdaten elektronisch zu veröffentlichen und dauerhaft zugänglich zu machen. Alle Veröffentlichungen erhalten einen Digital Object Identifier (DOI) und werden über nationale und internationale Bibliothekskataloge sowie Suchmaschinen nachgewiesen und auffindbar.
Neue Veröffentlichungen:
Visualization of parasite–host interactions using atmospheric-pressure MALDI mass spectrometry imaging
(2025) Wiedemann, Katja Rebecca
Endoparasites completely rely on the host organism to survive, once they entered their host. Though, hosts do not capitulate but try to protect themselves against potential damage induced by the parasite. Taking these two effects together, leads to measurable changes in the composition and lateral distribution of metabolites in host tissue (upon infection). In order to find novel drug targets, further knowledge on such changes is crucial. Using mass spectrometry imaging to investigate host-parasite interactions in vivo in an untargeted fashion whilst maintaining the lateral information of metabolites is a powerful approach. Therefore, two distinct models were studied: Schistosoma-mansoni-egg-containing liver samples of hamsters infected with the blood flukes, and bovine skin tissue, showing cysts formed by the apicomplexan parasite Besnoitia besnoiti.
For both parasite-host systems, characteristic infection markers were found with significant changes in signal intensities.
Additionally, by benefiting from the fact that lateral information is kept during mass spectrometry imaging analysis, the lateral distribution of infection markers was revealed. For some of them, co-localized biological structures were observed in optical images of the analyzed tissues.
During schistosomiasis, Schistosoma mansoni eggs are deposited in the hamster liver, leading to granuloma formation around the eggs. The high lateral resolution of the AP-SMALDI5 AF ion source enabled the unambiguous visualization of both, eggs (100 µm to 200 µm in diameter) and local abundance changes of lipids in granulomatous tissue compared to healthy hepatic tissue. Guided by results obtained with liquid chromatography-tandem mass spectrometry, we observed a substructure in formed granulomas by applying mass spectrometry imaging. For example, ether-phosphatidyl-ethanolamines were mainly found in the outer part of the granulomas. In total, 372 substances were found to be significantly changed due to infection.
In the skin of Besnoitia besnoiti-infected cattle, MS images showed both, enrichment and depletion of several lipid species inside parasite-formed cysts. Due to the high lateral resolution at 2 µm pixel size, some of them were even found to be characteristic for the thin cyst walls. Applying multiple MSI methodologies, cysts were further characterized by on-tissue tandem mass spectrometry as well as 3-dimensional imaging. Overall, 552 ions were found to be altered due to infection.
Overall, gained insights into parasite-host interactions can now be used as starting points for further metabolism studies and also serve as potential drug targets.
For both parasite-host systems, characteristic infection markers were found with significant changes in signal intensities.
Additionally, by benefiting from the fact that lateral information is kept during mass spectrometry imaging analysis, the lateral distribution of infection markers was revealed. For some of them, co-localized biological structures were observed in optical images of the analyzed tissues.
During schistosomiasis, Schistosoma mansoni eggs are deposited in the hamster liver, leading to granuloma formation around the eggs. The high lateral resolution of the AP-SMALDI5 AF ion source enabled the unambiguous visualization of both, eggs (100 µm to 200 µm in diameter) and local abundance changes of lipids in granulomatous tissue compared to healthy hepatic tissue. Guided by results obtained with liquid chromatography-tandem mass spectrometry, we observed a substructure in formed granulomas by applying mass spectrometry imaging. For example, ether-phosphatidyl-ethanolamines were mainly found in the outer part of the granulomas. In total, 372 substances were found to be significantly changed due to infection.
In the skin of Besnoitia besnoiti-infected cattle, MS images showed both, enrichment and depletion of several lipid species inside parasite-formed cysts. Due to the high lateral resolution at 2 µm pixel size, some of them were even found to be characteristic for the thin cyst walls. Applying multiple MSI methodologies, cysts were further characterized by on-tissue tandem mass spectrometry as well as 3-dimensional imaging. Overall, 552 ions were found to be altered due to infection.
Overall, gained insights into parasite-host interactions can now be used as starting points for further metabolism studies and also serve as potential drug targets.
Dynamic critical behavior of hot and dense QCD matter from the real-time functional renormalization group
(2025) Roth, Johannes
In this work, we study dynamic critical behavior of hot and dense QCD matter near second-order phase transitions. We consider the chiral phase transition for two flavors of massless quarks, as well as the conjectured critical point at physical quark masses and finite baryon chemical potential. These are plausibly in the same dynamic universality classes as a four-component Heisenberg antiferromagnet and the liquid-gas critical point of a pure fluid, respectively, whose critical dynamics are described by Models G and H in the Halperin-Hohenberg classification.
Our central tool in this work is a real-time generalization of the functional renormalization group (FRG) based on the Schwinger-Keldysh contour. Starting with Model G, we develop a novel formulation of the real-time FRG which preserves all relevant symmetries of dynamical systems with reversible mode couplings. We show that associated Ward identities imply exact statements about the FRG flow, including the non-renormalization of the mode-coupling constant, and the independence of the static free energy on the dynamics. We show that the formalism reproduces the non-trivial value z=d/2 for the dynamic critical exponent in d spatial dimensions, and we compute a novel scaling function which describes the universal temperature and momentum dependence of the iso-vector and iso-axial-vector charge diffusion coefficient in the chiral limit.
As a next step, we adapt this novel FRG technique to Model H. We derive analytical expressions for dynamic critical exponents that describe the universal power-law divergence of the heat conductivity and the shear viscosity near the QCD critical point. As a central result, we find that the critical exponent of the shear viscosity as a function of d exhibits a maximum in the range 2 < d < 4 and approaches zero for d=2 spatial dimensions. We verify the robustness of this result by considering improved truncations of the static free energy. In parallel, we emphasize the structural similarities and differences with Model G by comparing the fixed-point structures of both models and discuss the presence/absence of weak and strong dynamic scaling relations.
While the leading universal scaling behavior can be described by Models G and H, non-universal corrections require a real-time description of the microscopic dynamics. In this regard, we consider a real-time formulation of the quark-meson model as a particular low-energy effective theory for QCD. As a first application, we study the influence of bosonic dissipation on the phase diagram and the excitation spectrum. We find that dissipation has a non-vanishing but quantitatively small effect on equilibrium observables. The influence on the excitation spectrum, on the other hand, can be drastic, as (over-)damping potentially turns weakly-damped quasiparticles into purely relaxational excitations.
Our central tool in this work is a real-time generalization of the functional renormalization group (FRG) based on the Schwinger-Keldysh contour. Starting with Model G, we develop a novel formulation of the real-time FRG which preserves all relevant symmetries of dynamical systems with reversible mode couplings. We show that associated Ward identities imply exact statements about the FRG flow, including the non-renormalization of the mode-coupling constant, and the independence of the static free energy on the dynamics. We show that the formalism reproduces the non-trivial value z=d/2 for the dynamic critical exponent in d spatial dimensions, and we compute a novel scaling function which describes the universal temperature and momentum dependence of the iso-vector and iso-axial-vector charge diffusion coefficient in the chiral limit.
As a next step, we adapt this novel FRG technique to Model H. We derive analytical expressions for dynamic critical exponents that describe the universal power-law divergence of the heat conductivity and the shear viscosity near the QCD critical point. As a central result, we find that the critical exponent of the shear viscosity as a function of d exhibits a maximum in the range 2 < d < 4 and approaches zero for d=2 spatial dimensions. We verify the robustness of this result by considering improved truncations of the static free energy. In parallel, we emphasize the structural similarities and differences with Model G by comparing the fixed-point structures of both models and discuss the presence/absence of weak and strong dynamic scaling relations.
While the leading universal scaling behavior can be described by Models G and H, non-universal corrections require a real-time description of the microscopic dynamics. In this regard, we consider a real-time formulation of the quark-meson model as a particular low-energy effective theory for QCD. As a first application, we study the influence of bosonic dissipation on the phase diagram and the excitation spectrum. We find that dissipation has a non-vanishing but quantitatively small effect on equilibrium observables. The influence on the excitation spectrum, on the other hand, can be drastic, as (over-)damping potentially turns weakly-damped quasiparticles into purely relaxational excitations.
Insect mediated bioconversion in the circular bioeconomy: evaluation of quality, safety and environmental impact
(2024) Rossi, Giacomo
Industrially farmed insects are receiving increasing attention within the modern bioeconomy. Due to a diverse range of microorganisms living in their gut, insects are able to grow on biological waste and by-products, recover nutrients and produce new high-quality materials to be exploited within the agriculture, food, feed, medical and industrial sectors. Their high adaptability to different conditions, along with their limited production of greenhouse gasses, low use of resources, high feed conversion and valuable nutritional profile, has also suggested them as potential food and feed sources for the future. However, despite such interesting properties, legislative limitations, often led by fragmented and contradictory knowledge or lack of data, appear to be a serious limitation for their affirmation in the circular bioeconomy.
This thesis focuses on the evaluation of quality, safety and environmental impact of edible insects produced by applying circular economy concepts. Chapter 1 defines the overall background knowledge motivating the performed experiments. It offers an overview of the research gaps that form the basis for the experimental work and describes the overall structure of the thesis. A general introduction covering several aspects concerning the use of insects in the circular bioeconomy, with a specific focus on insects as waste management tool and as future food and feed is summarised in Chapter 2.
Chapter 3 represents the core of the thesis. Six experiments, carried out with the aim of answering the research questions defined in Chapter 1 and addressing the identified research gaps are presented and discussed. Specifically, section 3.1 focuses on the development of a new, non-destructive optical system for the rapid monitoring of quality changes of edible insect products. Fluorescence spectra of dry insect powders, produced by milling insects of five different species belonging to the Orthoptera order, were recorded. The 3D data were organised into an Excitation Emission Matrix (EEM) and analysed through machine learning tools. Five independent fluorescence peaks, each resulting from a different class of chemical compounds, were identified. The obtained results were therefore further applied to detect the oxidation status of insect paste subjected to high hydrostatic pressure (HHP) processing (section 3.2). Two experiments were conducted by applying HHP to insect paste at 600 MPa for 5 min. In the first experiment (experiment 2.1), three modified atmosphere packaging (MAP) and normal air packaging were applied after HHP treatment and microbial load as well as lipid and protein oxidation status were monitored during 28 days of refrigerated storage. Results suggested that the combination of HHP with oxygen-free MAP allowed shelf-life extension up to 10 days when refrigeration was applied. However, HHP treatment was found to be responsible for oxidation initialisation. Therefore, the second experiment (experiment 2.2) aimed to validate such observation and test whether addition of commercial antioxidant mixtures before applying HHP could delay the oxidation process. Results showed that although antioxidants exhibited their activity differently during the storage (with the synthetic antioxidant being more active in the initial stage of the storage while the natural antioxidant being more active in a later stage), HHP alone was not responsible for any significant oxidation.
Considering the most interesting aspect of edible insects regarding waste conversion, section 3.3 investigates the possibility of using black soldier fly larvae (BSFL) as a tool for managing waste from aquaculture production (ASW). Two experiments, the first using fresh (daily-collected) ASW and the second applying anaerobically digested (bulk-accumulated) ASW, were therefore carried out. The first experiment (experiment 3.1) demonstrated that BSFL can conveniently convert ASW; however, the high water content of the initial material required the inclusion of other ingredients in the diet. Mixtures consisting of 75% ASW and 25% of chicken feed were found to be optimal for supporting larval growth and waste conversion. However, the amount of nutrients assimilated by the larvae was extremely low, indicating a significant loss of nutrients. High nutrients retention and consequently a low environmental impact was observed in substrate 100ASW, which was characterised by low dry matter content, resulting in feed limitation for the BSFL. These results were further confirmed in the second experiment (experiment 3.2), which showed that conditions leading to high larval growth performances were negatively correlated with the reduction of environmental impact. Furthermore, experiment 3.2 also displayed low growth ability of BSFL on bulk accumulated ASW, indicating that fresh ASW should be preferred for insect-mediated aquaculture waste conversion processes. However, although these two experiments showed low nutrient retention by BSFL reared under optimal conditions, the actual amounts of nutrients lost by the larvae in form of gas were not quantified.
Therefore, in order to accurately quantify the gas emissions from edible insects during the rearing process, a new open dynamic gas emission chamber was designed and validated for monitoring the greenhouse gas (GHG) emissions from edible insects on a small scale (section 3.4). Validation experiment was carried out by rearing BSFL on moistened chicken feed. Obtained results showed that BSFL produced neither CH4 nor N2O, while CO2 production strictly depended on insect growth and metabolic activity. Accordingly, CO2 emission curves closely resembled the larval growth curves, indicating that an accurate estimation of GHG emission from insects should consider the overall life cycle of the insect, from eggs to harvesting stage, including the neonate stage.
Based on the obtained results, an overall conclusion highlighting the main findings and addressing the research questions defined at the beginning of the thesis is presented in the final chapter (Chapter 4). Relevance of the overall thesis within the circular bioeconomy framework and the future steps needed to promote a full transition to the circular bioeconomy, are also illustrated in this chapter.