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Item type: Item , Microbiome of honey bee corbicular pollen: Factors influencing its structure and potential for studying pathogen transmission(2025) Shi, Haoran; Ratering, Stefan; Schneider, Bellinda; Schnell, SylviaHoney bees are exposed to a diverse variety of microbes in the environment. Many studies have been carried out on the microbiome of bee gut, beebread, and flower pollen. However, little is known regarding the microbiome of fresh corbicular pollen, which can directly reflect microbes acquired from the environment. Moreover, although evidences have suggested that floral resources in general can affect the bee-acquired microbes, whether specific forage plants affect the composition of these microbes is still unclear. Here, we characterized both the microbiome and plant composition of corbicular pollen in collection seasons over two years from six hives using 16S rRNA gene and ITS2 metabarcoding. The results reveal temporal changes in the microbiome and plant composition in corbicular pollen, which was influenced by environmental factors and the choice of forage plants. We identified several co-occurrences between plant and bacterial genera, indicating specific plant-microbe interactions. Many Spiroplasma species with various insect hosts, including a honey bee pathogen Spiroplasma melliferum, were shown to positively correlate with Rubus, suggesting this plant genus as an important node for microbial transmission. Overall, we demonstrated the potential of corbicular pollen for studying the transmission of microbes, especially pathogens. This framework can be applied in future research to explore the complicated pollinator-microbe-plant network in different ecosystems.Item type: Item , Development and Characterization of a Cold Atmospheric Plasma Source for Clinical Application(2025-06-13) Moritz, SandraThe aim of this thesis was the development and characterization of a cold atmospheric plasma source (CAP) tailored for clinical applications. During experiments, various materials were tested in a long-term plasma afterglow environment for their suitability in CAP decontamination and as components for CAP sources, and afterwards a novel, adaptable CAP source was built and characterized. For the suitability-study, materials were chosen from different material groups, namely metals (stainless steel), glass (borosilicate glass) and polymers (polypropylene, rigid polyvinyl chloride and fluorinated ethylene propylene), representing typical materials used in the healthcare sector. <br> Here, different degrees of surface modification were found. While fluorinated ethylene propylene showed almost no modifications, slight to significant changes in free surface energy, surface morphology, surface composition and oxidation was found for the other materials, especially stainless steel. Additionally, sporicidal efficacy of the CAP source was proven, with a log10 reduction of Bacillus atrophaeus endospores of 4.3-6.2 within 15 minutes. Here, hydrophobic properties of the tested materials and hence layering and shielding of the bacteria showed the greatest limiting effect in spore reduction. <br> Based on these findings, the prototype of a CAP source was designed and constructed. Aim for this design was to create an adaptive, low-cost, efficient and durable plasma source. Hence, sputter-coating of the electrodes on a flexible dielectric material was tested. As dielectric, polyethylene naphthalate (PEN) foil was chosen because of its high dielectric strength and excellent chemical resistance. By sputter-coating, different electrode materials and electrode thicknesses were deposited onto the PEN foil and tested for their resistance against material modifications and for their endurance during plasma ignition. Based on its performance, palladium was chosen, with a thickness of 110 nm for both electrodes. <br> For this prototype (palladium-sputtered electrodes with thickness 110 nm on both sides), different characterization tests were done. Firstly, ozone measurements revealed plasma parameters for ozone and nitrogen mode. Secondly, laser microscopy showed the development of a border area on the edge of the grounded electrode. Thirdly, plasma diagnostical approaches indicated electron temperature, electron density and vibrational temperature for nitrogen mode, and plasma power was evaluated. Lastly, bactericidal efficacy was measured for different ozone mode plasma parameters and for nitrogen mode, using different CAP source prototypes. Here, within 5 minutes, a log10 reduction of 6.7 (nitrogen mode) and 5.3 (ozone mode) was achieved, respectively. <br> Endurance of the different plasma mode prototypes showed to differ, depending on the used plasma mode. While the nitrogen mode prototype burned through after almost 150 minutes, corresponding to 50 plasma ignitions, the two ozone mode prototypes still worked reliably after the end of the experiments. <br> An evaluation of the performance of the newly developed CAP prototype shows, that reduction efficacy is in the same order of magnitude, but with shorter required treatment intervals than the plasma source used during the material tests. At the same time, the newly developed prototype works with an power density, which is one order of magnitude lower than that used for the previous plasma source, indicating improved effectiveness. <br> To sum it all up, the experimental studies conclude, that the treatment with cold atmospheric plasma is a non-destructive and adaptable cleaning method for various materials. Combining CAP treatment with conventional sterilization methods could enhance the pathogen reduction, especially with regard to geometrically complex or heat-sensitive materials. PEN foil as dielectric has promise because of its characteristics and sputter-coating technique shows to be an adaptable and low-cost possibility to produce flexible and highly effective cold atmospheric plasma sources.Item type: Item , Consumers' Perception of and Preferences for Meat Safety and Quality in an Islamic LMIC Context: Empirical Evidence from Afghanistan(2025) Nasiri, MustafaGlobal trends in meat production and consumption are shifting significantly between High-Income Countries (HICs) and Low- and Middle-Income Countries (LMICs). In HICs, there is a growing trend of reducing or eliminating meat consumption due to health and environmental concerns, ethical considerations, and animal welfare. This has led to increased research and production of plant-based and lab-grown meat alternatives. Conversely, LMICs are experiencing rising meat demand due to population growth, urbanization, and a growing middle class. However, this rising demand is accompanied by increased food safety concerns and Foodborne Diseases (FBDs) which cause approximately 600 million illnesses, 420,000 deaths, and 33 million disability-adjusted life years (DALYs) annually. Animals and animal-sourced foods (ASFs) including meat are a key contributor to FBDs. Meat contamination can occur at various stages of the supply chain: pre-harvest, harvest, and post-harvest stages. Afghanistan, as an example of an Islamic LMIC, provides a compelling case study where rapid urbanization and a growing middle class have increased demand for high-value foods like meat, prompting modernization efforts in the meat industry in the past two decades. Traditional butcheries, however, continue to dominate the market, alongside emerging supermarkets that offer both fresh domestic sourced meat and refrigerated imported meat. Motivated by these dynamics, this research investigates Afghan consumers’ perceptions and preferences regarding meat quality and safety across the supply chain. It addresses three key questions: (i) How do consumers perceive meat quality and safety from farm to fork? (ii) How can purchases be influenced toward safer meat choices? (iii) What are the most important meat attributes driving consumer choices, and how does meat attachment influence these preferences? Using a mixed-methods approach, the study includes three analyses: perceptions of meat safety and quality, willingness to pay (WTP) for different meats, and preferences for meat attributes and attachment attitudes. The first study explores consumer perceptions of meat quality and safety at pre-harvest, harvest, and post-harvest stages using data from seven Focus Group Discussions (FGDs) with 52 participants in Kabul and Bamyan. The Total Food Quality Model (TFQM) was employed as the study’s analytical framework, and qualitative data were analyzed using MAXQDA software. Results revealed that at the pre-harvest stage, meats originating from the sedentary and nomadic livestock were perceived as safer than that from urban-raised animals. At the harvest stage, supermarket meat was viewed as more hygienic but less fresh. Consumers also raised concerns about its halal compliance, leading to lower trust in supermarket meat. In contrast, traditional butchery meat was deemed fresh and natural but unhygienic. At the post-harvest stage, key attributes influencing purchase decisions included color, freshness, place of origin, safety, and halal certification, with taste and tenderness being critical after purchase. Limited trust in supermarkets emphasized the need for better transparency and communication. The second study examines urban consumers’ WTP for four types of lamb meat, distinguished by their production systems (sedentary versus nomadic) and slaughtering and retail channels (traditional butchery versus supermarket). Using a second-price experimental auction mechanism, it assessed the impact of written framing, visual framing and psychological priming on WTP. Results showed no significant difference in WTP for sedentary versus nomadic meat at the aggregate level. However, higher-income and educated consumers preferred sedentary over nomadic meats. Participants also submitted higher bids for supermarket meat compared to traditional butchery meats. Moreover, written and visual framing effectively induced safer meat choices, while psychological priming had no significant impact. Findings further showed a positive and significant relationship between risk-taking attitude and WTP for safest meat choice, which may suggest opportunities for targeted marketing to promote food safety. The third study analyses consumer preferences for lamb meat attributes using a Best-Worst Scaling (BWS) approach and validates the Meat Attachment Questionnaire (MAQ) in an Islamic LMIC context. Results highlighted food safety certification, freshness, and halal labeling as the most important attributes, reflecting cultural and religious priorities. Preferences for meat attributes were generally heterogenous. High-income and educated consumers, as well as occasional consumers emphasized preferences for several attributes including food safety certification, cleanliness, breed, brand, and halal label. Additionally, confirmatory factor analysis validated the MAQ in an Islamic LMIC context, revealing that subscales such as hedonism and dependence were negatively associated with preferences for most meat attributes. This finding may underscore the role of cultural and psychological factors in shaping attitudes towards meat. Together, these studies provide valuable insights into Afghan consumer preferences and perceptions of meat safety and quality, with broader implications for LMICs undergoing meat industry modernization. Findings emphasize opportunities to build consumer trust in supermarkets by improving communication about halal compliance and food safety standards. Investments in infrastructure and hygiene training for traditional butcheries can address trade-offs between freshness and safety. Marketing strategies using written and visual framing can steer consumers toward safer meat choices. Policy and practical implications are also significant. Aligning meat production with cultural norms and halal requirements is essential for meeting Muslim consumer expectations, specifically by non-Muslim countries exporting meat to Muslim countries. Moreover, emphasizing food safety certification and transparency can enhance public health and trust among consumers, allowing supermarket to thrive in the market. The study also highlights the importance of fostering trust in formal institutions like supermarkets and offers transferable insights for other Islamic LMICs with similar dual meat supply chains. Future research could explore these dynamics across different meat types and regions, contributing to the literature on consumer behavior and meat industry modernization in LMICs.Item type: Item , Function of the urethral tuft cell deciphered by genetic models allowing cell type-specific activation(2025) Lafee, MahmoudBrush cells (synonym: tuft cells) are found in the epithelium of the mammalian respiratory, gastrointestinal and urinary tract. They are sensors for hazardous substances, and they release acetylcholine and other mediators (e.g. cysteinyl-leukotrienes and interleukin-25), which activate various cell types including immune cells and nearby sensory nerve fibers. In nose and trachea, these nerve fibers then release the neuropeptide substance P (SP), leading to neurogenic inflammation, a local defense reaction. In the urethra, their stimulation evokes micturition, and previous work of our laboratory using a broadly acting compound also gave first indication of a link of urethral tuft cells (UTC) to neurogenic inflammation. Based on this initial evidence, the present study aims to further investigate their role in inducing neurogenic inflammation by a) establishing a model for the selective activation of brush cells, and b) utilizing a model of brush cell-deficient mice. We used 1) a chemogenetic model, in which brush cells carry a DREADD (designer receptor exclusively activated by designer drugs) 2) an optogenetic approach, using a mouse line (Chat-ChR2-EYFP) expressing a fusion protein of the blue light-sensitive ion channel channelrhodopsin-2 (ChR2) and enhanced yellow fluorescent protein (EYFP) expressed under the control of the choline acetyltransferase (Chat) promoter, and 3) mice lacking UTC due to genetic deletion of the transcription factor Pou2f3. Explanted urethrae from these mouse models were exposed to appropriate stimuli (CNO [clozapine N-oxide] for DREADD, blue LED light for ChR2, denatonium as bitter compound, and capsaicin as UTC-independent activator of nociceptors), and the supernatant was analyzed for content of SP by ELISA. The chemogenetic model proved not to be suitable, since CNO (60 μM) caused SP release also from DREADD control urethrae, likely due to leaky expression of the transgene. In the optogenetic model, UTC-specific expression of the transgene was validated by immunofluorescence with antibodies against the UTC marker DCLK1 (double-cortin like kinase 1) (90% colocalization, 47/52 cells, from 5 animals) and against neuropeptides of sensory nerve fibers (no colocalization). Blue LED light evoked SP release only from urethrae of transgenic but not of control mice. This was fully sensitive to mecamylamine, a general nicotinic acetylcholine receptor inhibitor. The bitter tasting compound denatonium (5 mM) evoked SP release from urethrae of wildtype, but not from urethrae lacking UTC (Pou2f3-/-), whereas the direct nerve fiber activator capsaicin (1 mM) was equally potent in both strains. The data validate Chat-ChR2-EYFP mice, but not Trpm5-DREADD mice, as a suitable model for studying UTC function. This model and the use of the bitter tastant denatonium in conjunction with UTC-deficient mice (Pou2f3-/-) showed that direct stimulation of UTC leads to the release of neuropeptides (SP) from sensory nerve fibers, most probably through the release of acetylcholine from the activated tuft cells acting on nicotinic receptors on nerve fibers. Thus, UTCs not only trigger long-distance reflexes involving the bladder but also evoke neurogenic inflammation, representing a local defense reaction.Item type: Item , Veränderungen des pharyngealen Luftweges während und nach Klasse II:1-Therapie mittels Herbst-Multibracket-Apparatur(2024) Sonntag, GianlucaEs konnte bereits mehrfach gezeigt werden, dass sich der Posterior Airway Space (PAS) während der Herbst-Multibracket-Behandlung vergrößert. In der Literatur werden jedoch immer wieder große interindividuelle Variationsbreiten konstatiert und die bisherigen Untersuchungen basieren auf eher kleinen Probandenzahlen. Daher war das Ziel der vorliegenden Untersuchung, die PAS-Änderungen während und nach der Behandlung mit der Herbst-Apparatur und der anschließenden Multibracket-Apparatur bei einer großen Stichprobe von Klasse II:1-Patienten zu untersuchen und mögliche prätherapeutische Einflussfaktoren zu bestimmen. Daher wurden die Unterlagen von 503 ehemaligen Klasse II:1-Patienten (Overjet = 7,8 ± 2,4mm, ANB-Winkel = 5,0 ± 2,1°), die im Alter von 13,8 ± 3,4 Jahren eine Herbst-Multibracket-Behandlung erhalten hatten, untersucht. Fernröntgenseitenbilder (FRS) von vor der Behandlung (T0), nach 24,9 ± 9,2 Monaten Behandlung (T1) und 26,1 ± 8,0 Monate nach dem Behandlungsende (T2) wurden hinsichtlich der Fläche A(PAS) und der Veränderungen der linearen Abstände (p, t, pC2, pC3, pC4) analysiert. Zusätzlich wurden folgende mögliche prätherapeutische Einflussfaktoren bewertet: Overjet, ANBWinkel, Wits-Bewertung, ML/NSL-Winkel, ArGoGn-Winkel, Alter und skelettale Reife. Im Durchschnitt vergrößerte sich die Fläche A(PAS) während der Herbst-Multibracket-Behandlung um 23% und blieb danach konstant (± 0%). Alle linearen Abstände p, t, pC2, pC3, pC4 vergrößerten sich ebenfalls (6-19%) während T1-T0 und zeigten eine weitere Zunahme (1-7%) während T2-T1. Für alle Variablen gab es große individuelle Unterschiede. In Bezug auf mögliche Einflussfaktoren der PAS-Veränderungen wurden signifikante Zusammenhänge für das Wits appraisal und die Fläche A(PAS), sowie das Alter der Patienten und die Strecke pC4 beobachtet. Bei jüngeren Patienten und solchen mit einem großen Wits appraisal vor Beginn der Therapie wurden deutlichere Zunahmen des PAS festgestellt.