Dissertationen/Habilitationen

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Die Rolle von Ceramiden und assoziierten Faktoren in der Bildung von Coronavirus-induzierten replikativen Organellen
(2025) Salisch, Florian
RNA viruses have evolved diverse strategies to re-program and exploit host cellular functions and molecules, including cellular lipids, to ensure efficient virus replication and production of infectious virus progeny. A conserved feature of plus-strand RNA virus replication is the formation of membranous microenvironments (replicative organelles, ROs) in virus-infected cells. RO formation is known to be initiated by virus-encoded membrane-associated nonstructural proteins and involves extensive remodeling of host cell membranes. This process is thought to involve cellular enzymes responsible for synthesizing and modifying specific lipids. In this study, I investigated the potential roles of specific cellular sphingolipids and enzymes acting on sphingolipids in the replication of different coronaviruses. The data revealed that, following infection, cellular ceramide species increase significantly, whereas sphingomyelin levels decreased, indicating an involvement of sphingomyelinases that convert sphingomyelin to ceramide. To verify this, I targeted the cellular sphingomyelinases using pharmacological and genetic approaches. I could provide evidence that neutral sphingomyelinase 2 (nSMase2) plays an essential role in an early phase (but not entry) of coronavirus replication in Huh-7-ACE2 cells. Furthermore, I was able to demonstrate a colocalization of neutral sphingomyelinase 2 and ceramide, but not sphingomyelin, with both infection-induced and genetically induced ROs. Ceramides and coronaviral ROs were found to colocalize in different cell systems used in this study. However, in another set of experiments, I also obtained data to suggest that the extent of specific sphingolipid deregulations and the role of nSMase2 in coronavirus infections may vary among different infection systems, depending on the cell type used. Taken together, this study strongly suggests that ceramides serve as crucial lipid building blocks in the formation of coronaviral ROs in different cell types, suggesting that inhibition of cellular ceramide production may represent a potential antiviral strategy against coronavirus infections. However, the mechanisms of ceramide generation or recruitment to specific intracellular sites seem to vary depending on the cell type used and, possibly, the baseline ceramide levels in these cell types. Further investigation is required to clarify these variations and their biological implications.
Die sprachlich-diskursive Legitimation von Militäreinsätzen. Eine diskurslinguistische Analyse französischer Parlamentsdebatten zur Opération Serval (Mali)
(2025) Sommer, Luana
Die Dissertation leistet einen Beitrag zur Erforschung der sprachlich-diskursiven Legitimation von Militäreinsätzen und untersucht anhand eines Korpus französischer Parlamentsdebatten die Legitimierung der "Opération Serval" (Mali). Das im Zuge der Arbeit entwickelte, diskurslinguistische "Modell der Makromechanismen der Legitimation" (MML) eröffnet die Möglichkeit einer systematischen Analyse solcher Legitimationsvorhaben und bildet zugleich eine Grundlage, diese einer fundierten Kritik zu unterziehen.
Genetic study of Red Maasai sheep and their Dorper crossbred’s performance in sub-Saharan Africa
(2025) Oyieng, Edwin Pancras
The aim of this thesis was to study the performance of the Red Maasai sheep, the Dorper sheep and their crosses reared in a semi-arid environment. The study involved the analysis of reproduction parameters, survival of lambs and ewes length of productive life, the impact of heat stress on growth, and developed novel resilience phenotypes for the sheep population. The main breed groups in the breeding program comprised pure Dorper (DDDD), pure Red Maasai (RRRR), 75%Dorper-25%Red Maasai (DDDR) and 50%Dorper-50%Red Maasai – F1 (DDRR). R and ASReml-R software were used to evaluate reproduction parameters. Survival of lambs and the length of productive life of ewes were analysed using Cox and Weibull hazard models of the Survival Kit Version 6.12 software. Random regression models fitted with reaction norm functions were used to assess the impact of heat stress on growth and derive novel resilience phenotypes for growth in response to different levels of heat stress. Information generated through studying the reproductive performance of the flock is presented in Chapter 2. The pure Red Maasai sheep had significantly lower values for average age at first lambing (AFL), ewe birth weight (EBWT), ewe weaning weight (EWWT), litter birth weight (LBWT) and litter weaning weight (LWWT) compared to other breeds studied. The birth type (single or twins), sex of the lamb and parity in which the lambs were born significantly affected ewes’ birth and weaning weights. The overall heritability estimates of AFL (0.09±0.04) and LI (0.00±0.01) were not significant (P>0.05) while the heritability estimates for EBWT (0.38±0.04), EWWT (0.23±0.03), LBWT (0.19±0.03) and LWWT (0.09±0.02) were significant (P<0.05). The repeatability estimates were low for LBWT (0.25), LWWT (0.16) and that of lambing interval (LI) was near zero. Genetic and phenotypic correlations showed strong positive relationships between ewe and lamb weights. The Red Maasai had higher genetic and phenotypic correlations and genetic gains for the traits studied compared to the pure Dorper while the DDRR breed combination had a higher genetic gain among the crosses. LI had negative genetic correlations with LBWT and LWWT while AFL had positive genetic correlations with LBWT and LWWT. The phenotypic trends for AFL and LWWT showed a negative association with rainfall index over the years. Chapter 3 presents the results of pre- and post-weaning lamb survival to yearling, and ewes length of productive life. The pure Red Maasai lambs and ewes had better pre-weaning lamb survival rates and better productive life compared to the other breeds. Overall, 95% and 83% of lambs survived to weaning (90 days) and yearling (365 days), respectively. The Red Maasai lambs had the lowest mortality rates (2%) while Dorper lambs had the highest post-weaning mortality (24%) among the breeds. Lamb survival was significantly influenced by the season of birth, parity in which the lambs were born, birth type (single or twin) and birth weight. Single born lambs, those born during the wet season, offspring of multiparous ewes, and those having higher birth weights (>3kg) were associated with lower mortality risks. Ewe longevity was significantly affected by the breed, age at first lambing, parity and birth weight. Ewes of DDDR breed combination and those that had heavier birth weights (>3Kgs) had the highest risk of being culled, while ewes with a higher age at first lambing (>975 days old) and more than one lambing were less likely to be culled. Pre-weaning heritability estimates for survival (0.10–0.14) were higher than post-weaning estimates (0.01-0.05). The Red Maasai had the highest genetic gain for pre-weaning survival (-0.026) compared to DDDR (-0.018), F1 (-0.011), and Dorper (-0.012). General weakness, often due to poor nutrition, posed the highest risk for of lambs dying post-weaning (12.99 risk ratio), followed by diseases like enterotoxemia and sheep pox (6.006 risk ratio). The impact of heat stress on the growth of sheep and novel resilience phenotypes for growth are presented in Chapter 4. Heat stress, expressed as Temperature-Humidity Index (THI), significantly affected the growth of the sheep. The Red Maasai sheep had a higher tolerance for heat stress compared to the other breeds studied. The THI break points, when growth is affected by heat stress, were 78.75, 78.71, 78.42 and 77.93 for RRRR, DDDD, DDRR and DDDR respectively. At the THI break point, the growth rate declined at a rate of 0.06 Kgs, 0.09 Kgs, 0.05 Kgs and 0.15 in live weight gain per unit change in THI for RRRR, DDDD, DDRR and DDDR respectively. Random regression models fitted with reaction norm functions were used to develop two resilience phenotypes namely: Response and Stability. These resilience phenotypes were developed at THI 70 (representing low/no heat stress) and THI 85 (representing high heat stress). The breed, sex, type of birth, dams’ parity and season of birth significantly affected the stability of growth at low and high heat stress. Genetic correlations of resilience phenotypes at THI 85 with pre-weaning live weight gain (LWG1) were antagonistic and significant but not for post-weaning live weight gain (LWG2). Strong positive genetic and phenotypic correlations existed between response and its corresponding stability trait. The heritability estimates of resilience traits ranged from 0.12 for Response at THI 70 to 0.16 for Stability at THI 85. The better lamb survival and ewe longevity, and high tolerance to heat stress of the Red Maasai breed are an indication of their suitability for the harsh environment. Crossbreeding of the Red Maasai with Dorper has the potential to optimize growth and reproductive efficiency in the semi-arid environment. The moderate heritability estimates for resilience phenotypes in the population studied highlight opportunities for selective breeding to enhance resilience for growth under the changing climatic conditions. Context-specific improved animal management practices can increase the survival of lambs, improve their reproductive performance and reduce the impact of heat stress on growth
Luminescent and Conductive Hybrid Materials based on Nanoscale Metal-Organic Frameworks and (Bio)Polymers
(2025-05) Maxeiner, Moritz
This PhD thesis is centred around a unifying theme: the design and fabrication of hybrid materials that integrate nanoscale metal-organic frameworks (nanoMOFs) with (bio)polymers, targeting advancements in materials science and greener chemistry. A multi-faceted research approach has been applied to address this topic, with three main objectives: first, to synthesise nanoscale versions of bulk MOFs known from the literature; second, to develop nanoMOF@polymer hybrid materials with multi-level anti-counterfeiting mechanisms; and third, to synthesise environmentally friendly nanoMOF@biopolymer materials according to green chemistry principles. During the elaboration of the set scientific scope, all key objectives were successfully achieved, leading to notable achievements in the areas studied. A surfactant-assisted bottom-up synthesis route has successfully produced nanoMOFs with enhanced photophysical and morphological properties compared to their bulk versions. Mixed-matrix-membranes (MMMs) and powders composed of lanthanide-containing nanoMOFs (nLn³⁺-MOFs) and anthropogenic polymers (APs) have been developed, exhibiting multi-level anti-counterfeiting with interconnected properties, making them highly secure and difficult to replicate, thereby suitable for security-related applications. Aiming towards sustainability, developed nLn³⁺-MOFs were combined successfully with biopolymers yielding biodegradable and recyclable MMMs, hydrogels and cryogels. These bio-based materials demonstrating high regeneration capacity and stability over multiple recycling steps, align with green chemistry principles. Dispersibility and particle distribution benefit from the nanocharacter of nLn³⁺-MOF particles, which is a critical requirement for stable and resilient hybrid materials. The visible (Vis= Eu³⁺, Tb³⁺) and invisible (NIR= Yb³⁺) photoluminescence of developed nLn³⁺-BDC (BD^C2−= benzene-1,4-dicarboxylate), together with the conductivity of the APs polystyrene sulfonate (PSS) and pyrolysed resorcinol-formaldehyde (pRF) were used to create an additive multi-level anti-counterfeiting. Each feature (Vis-light, NIRlight, conductivity) represents a certain level of security, while they are interconnected by optical and physical properties – changing one will inevitably change another of the levels. The materials developed are designed to be difficult to replicate for unambiguous marking of valuable goods. As materials science has to address sustainability to overcome environmentally relevant challenges in the future, APs have been replaced by biodegradable nature-based biopolymers agar and gelatine. Luminescent MMMs made from nEu³⁺-BDC@biopolymers have been successfully recycled ten-times, while the red luminescence allows for the monitoring of the material’s condition. Resilient nEu³⁺-BDC in boiling water and freezing temperatures as well as water-based synthesis routes, render these materials suitable alternatives for AP-based hybrid materials. Altogether: improved synthesis techniques, application-driven approaches and biodegradable alternatives enable the creation of advanced nanoMOF@(bio)polymer hybrid materials supporting anti-counterfeiting, sustainability and circular economy.
Entwicklung eines Diagnoseschlüssels für die Innere Medizin des Pferdes anhand einer retrospektiven Studie von 13.550 Fällen aus den Jahren 2000 - 2020
(2024) Klinkel, Samira
Eine retrospektive Auswertung von Patientendaten der Klinik für Pferde, Innere Medizin (PFI), der Justus-Liebig-Universität Gießen bildete die Grundlage für das Hauptziel dieses Dissertationsprojektes, die Entwicklung eines speziesspezifischen Diagnoseschlüssels für internistische Diagnosen bei Pferden. Die Daten umfassten alle Pferde, Ponys und Esel, die von 2000 bis 2020 in der PFI ambulant oder stationär behandelt wurden. Der Hauptzielparameter bestand in der individuellen Hauptdiagnose, die anhand eines ersten Diagnosekatalogs eingeteilt und verschlüsselt wurde. Dieser erste Diagnoseschlüssel enthielt 14 Hauptgruppen, meist basierend auf Organsystemen. Jede Hauptgruppe war in maximal vier Stufen unterteilt, um die Diagnosen zu hierarchisieren. Pro Fall wurde eine Haupt- und bis zu zwei Nebendiagnosen, Outcomes und patientenbezogene Angaben wie Alter, Geschlecht, Rasse, Dauer des Aufenthalts, Erkrankungsdauer und eventuelle Wiedervorstellungen in eine Exceltabelle überführt. Über 21 Jahre (Januar 2000 bis Dezember 2020) wurden die Daten von 14.034 Patienten der PFI erfasst. Es wurden 484 Begleitpferde ausgeschlossen, was zu 13.550 Hauptdiagnosen führte. Die jährliche Patientenanzahl variierte zwischen 497 (2000) und 822 (2019), mit einem Median von 626. Das Durchschnittsalter der Patienten stieg von 9,9 (2000) auf 13,7 Jahre (2020), was eine hoch signifikante Zunahme (p < 0,0001) um ca. 2 Monate pro Jahr ergab. Die Verteilung des Geschlechts zeigte leichte Anstiege von Wallachen und Stuten, während die eh geringe Hengstanzahl weiter abnahm. Warmblüter bildeten mit 56,3 % die größte Rassegruppe. Über die Jahre nahm ihr prozentualer Anteil ab, während Kleinpferde zunahmen (p < 0,0001). Die stationäre Aufenthaltsdauer reduzierte sich signifikant (p < 0,01) von im Median 5,0 Tagen (2000-2002) auf 3,2 Tage (2018-2020). Der ganz überwiegende Anteil (83,5 %) der Patienten wurde einmalig vorgestellt, 11,9 % hatten mindestens eine Wiedervorstellung aufgrund der selben Erkrankung und 4,6 % wurden aufgrund anderer Symptome erneut vorgestellt. Die meisten Patienten wiesen ein perakutes Geschehen auf, dabei handelte es sich ganz überwiegend um Koliker. 67,4 % aller Patienten konnten entlassen werden, 18,6 % wurden in die Klinik für Pferde, Chirurgie und Orthopädie (PFC) ganz überwiegend (91 %) zur Kolikoperation überwiesen. In der PFI mussten 13,2 % der Patienten euthanasiert werden, 0,2 % verstarben und 0,3 % wurden in externe Kliniken überwiesen. Die Überweisungen in die PFC nahmen über die Zeit ab, während der Anteil an euthanasierten und verstorbenen Patienten zunahm, was mit dem höheren Alter der Patienten zusammenhängen könnte. Die Erkrankungen des Verdauungstraktes überwogen mit 9.039 Fällen (66,7 %). Diese wurden überwiegend durch Koliker repräsentiert. Magenerkrankungen stiegen von 11 Fällen in den ersten drei Jahren auf 193 Fälle in den letzten 3 Jahren des betrachteten Zeitraums deutlich an. Respiratorische Erkrankungen waren mit 1.558 Fällen (11,5 %) die zweit größte Hauptgruppe mit der chronisch obstruktiven Bronchitis (Equines Asthma) als häufigster Diagnose innerhalb der Atemwegserkrankungen (61,9 %). Das Herzkreislaufsystem war in 795 Fällen (5,9 %) betroffen, wobei sich von 634 kardialen Fällen 400 als Herzklappeninsuffizienzen erwiesen. Die Sammelgruppe der systemisch erkrankten Pferde machte mit 4,0 % (n = 544) aller Patienten die viert größte Gruppe aus, am häufigsten wurden hier Patienten mit Fieber (39,3 %) und Abmagerung (16,7 %) unklarer Genese einsortiert. Die Erkrankungen von Haut, Haaren und Lymphknoten kamen in 2,2 % der Gesamterkrankungen vor (302 Fälle). Die Einteilung im ersten Diagnoseschlüssel führte dazu, dass die Infektion der Lymphknoten mit Streptococcus equi. ssp. equi (Druse) 22,2 % der Patienten dieser Gruppe ausmachte. Harn- und Geschlechtsorgane waren in 242 Fällen (1,8 %) betroffen, wobei ein Anstieg von Niereninsuffizienzen von 5 Patienten in den ersten drei Jahren auf 24 Fälle in den letzten drei Jahren des betrachteten Zeitraums auffiel. In die weiteren sieben Hauptgruppen wurden zwischen 58 und 229 Fälle eingeteilt. Auf Basis dieser Auswertungen und inspiriert von der internationalen statistischen Klassifikation der Krankheiten und verwandter Gesundheitsprobleme der Weltgesundheitsorganisation (WHO) erfolgte eine Optimierung des ersten Diagnoseschlüssels. Hauptgruppen wie Haut/Haare und Lymphknoten, Herz/Kreislauf sowie Harn- und Geschlechtsapparat wurden geteilt, neue Hauptgruppen für Lymph- und Blutsystem, Sinnesorgane und Ernährungsstörungen geschaffen und zahlreiche Diagnosen ergänzt. Zudem können darin Vergiftungen, Verhaltensstörungen und unerwünschte Arzneimittelwirkungen klassifiziert werden. Die Anwendung des optimierten Diagnoseschlüssels in Pferdepraxen und –kliniken könnte maßgeblich dazu beitragen, basierend auf hohen Fallzahlen exakte Kenntnisse zu Diagnosehäufigkeiten in der Pferdemedizin zu erlangen, um daraus Forschungs- wie Ausbildungsschwerpunkte abzuleiten.
Echoes of the Persian Heritage, Rhythms of Modernity: Life-Worlds in Flux : A Critical Exploration of Inter/Transmedial Configurations from Golestan to Beyzaie
(2025) Alinezhadi, Ehsan
This dissertation examines intermedial and transmedial storytelling in Iranian New Wave cinema, focusing on how selected films, both adapted and non adapted, mediate cultural narratives through medium-specific aesthetics to construct hybrid cultural identities and narrative worlds. Case studies include but not limited to the film adaptations, like Dariush Mehrjui’s The Postman 1972, based on Büchner’s Woyzeck, alongside original films such as Bahram Beyzaie’s The Crow 1977. Situating Iranian New Wave cinema within a a broader cultural framework while reading it through intermedial and transmedial concepts and configurations, drawing on Mieke Bal’s “travelling concepts,” Homi Bhabha’s notion of “Third Space”, and Werner Wolf’s inter/transmedial theory, this study analyzes film’s mise-en-scène, editing, and cinematography to trace how narrative elements and cultural signifiers circulate and transform across cultural and inter/transmedial dynamics. For example, The Postman explicitly critiques Iran’s rapid top-down modernization and its inevitable consequences, particularly the conflict between emerging modern structures and traditional life-worlds. In The Crow, Beyzaie portrays a modernizing Tehran through the story of a female protagonist who struggles to assert her rejected individuality. By revealing how 1960s–70s Iranian New Wave cinema both reflects and shapes a culturally hybrid society, this dissertation contributes to the discussions around film studies, cultural studies, narratology, and adaptation theory by offering an interdisciplinary model linking narrative form, media, and socio-cultural context.
Stable and Unstable: Binary Opposition in Pnictogens
(2025) Qian, Weiyu
The stability and instability is one of the most fundamental dualities in chemistry, which governs the essence of reactivity with a linkage of energy through kinetic and thermodynamic principles, as well as quantum-mechanical tunneling. The "unstable" species, driven by a natural inclination, strives to transform into a "stable" state, minimizing energy and pushing the reaction equilibrium. Conversely, a "stable" species must be "compelled" into an unstable state—whether by external forces or chemical manipulation—to unlock its reactivity or achieve energy storage. This dynamic relationship underscores the intrinsic interdependence of stability and instability; they are not absolutes but rather exist in a state of constant tension, capable of mutual inversion depending on context and conditions. From a philosophical perspective, stability and instability can be viewed as two sides of the same coin (like Apollonian and Dionysian, from Die Geburt der Tragödie aus dem Geiste der Musik, Friedrich Nietzsche), where each defines and elevates the significance of the other. Stability gives instability its allure of transient, prompting the quest to capture fleeting species that defy conventional norms. Meanwhile, instability imbues stability with its intrinsic value, as the effort to stabilize the ephemeral drives innovation in chemistry. This duality reflects a broader natural order, where opposites not only coexist but also fuel progress, challenge boundaries, and inspire creativity. In this thesis, I’m going to constitute unstable "oligomer" (higher neutral nitrogen allotropes) with the units of stable dinitrogen, explore methods to generate and study the chemistry of unstable heavier analogs of stable dinitrogen, and investigate novel properties of highly reactive, electron-deficient species that violate the octet rule in main group elements. This endeavor embodies a philosophical and scientific journey—transforming the transient into the tangible, the unstable into the cherished, and the elusive into the achievable. In the first publication, the interstellar candidate phosphorus mononitride PN, a metastable species under ambient conditions, was generated through high-vacuum flash pyrolysis of (o-phenyldioxyl)phosphinoazide in cryogenic matrices. Moreover, an elusive o-benzoquinone-PN complex formed and its recombination to (o-phenyldioxyl)-λ5-phosphinonitrile was observed upon irradiation with the light λ = 523 nm, which demonstrates for the first time the reactivity of PN towards an organic molecule. In the second publication, we report the in situ characterization of triplet phenylarsinidene by matrix-isolation infrared and UV/Vis spectroscopy. Doping the matrices containing phenylarsinidene with molecular oxygen leads to the formation of hitherto unknown kinetic intermediate anti-dioxyphenylarsine, which demonstrates a completely different reactivity with corresponding phenylnitrene and phenylphosphinidene. The anti-dioxyphenylarsine undergoes isomerization to novel dioxophenylarsine upon 465 nm irradiation. In the third publication, we report the synthesis and spectroscopic characterization of vinylarsinidene, a higher congener of vinylnitrene. Triplet vinylarsinidene was characterized by IR and UV/Vis spectroscopy and displays remarkably rich unimolecular photochemistry. Upon selective photoirradiation, it rearranges to vinylidenearsine, 2H-arsirene, or an arsinidene (H–As) acetylene complex. Furthermore, the stability of vinylphosphinidene was projected with multireference computations. In the fourth publication, the first example of scalably synthesizable neutral nitrogen allotrope, C2h-N6 was prepared in the gas-phase at ambient temperature, followed by characterized in argon matrices at 10 K or neatly as a film at liquid nitrogen temperature (77 K), demonstrating unexpectedly high stability. Energetic performance computations at the CCSD(T)/cc-pVTZ level with Kamlet-Jacob equation predict an excellent detonation performance over several well-known explosives, for example, TNT (2,4,6-trinitrotoluene) and RDX (1,3,5-trinitro-1,3,5-triazinane).
Matrix-assisted laser desorption/ionization mass spectrometry imaging for the analysis of pro-and anti-inflammatory macrophages and murine and human atherosclerotic tissue samples
(2025) Khamehgir-Silz, Pegah
The primary objective of this dissertation is the use of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI MSI) for the visualization and characterization of pro- and anti-inflammatory macrophages as well as atherosclerotic plaques in murine models and human tissue samples. In the first publication, a comprehensive methodology was developed to distinguish pro- and anti-inflammatory human macrophages using MALDI-MSI, RT-qPCR, and FACS. The macrophage subtypes M1, M2a, and M2c could be successfully distinguished based on expression profiles of marker genes using RT-qPCR and FACS. A comprehensive working protocol for the preparation, measurement and data analysis for MALDI-MSI was developed and established. The method identified subtype-specific markers and showed good reproducibility in three biological replicates based on principal component analysis (PCA) and hierarchical cluster analysis (HCA). The heterogeneity of cells from different donors became apparent when the number of biological replicates was increased from 3 to 6. Due to the biological variability of cells derived from various donors, identifying universal markers for in-vitro stimulated human macrophages posed challenges. In the second publication, lipid markers associated with plaque formation and development in ApoE-/- mice were successfully identified, and their presence in human atherosclerotic tissue was investigated. The determined results clearly showed differences in the lipid profile of the older ApoE-/-mice compared to the wild-type mice. Thirty-one compounds that were exclusively detected in the ApoE-/- mice were identified as markers. The results of the human atherosclerotic tissue samples showed significantly different lipid profiles, making it difficult to identify universal markers. However, in particular tissue samples, it was possible to detect markers identified in the murine plaques tissue samples. These findings demonstrate a patient-specific lipid profile and support previous findings suggesting that clinically significant atherosclerotic plaques contain a variable mixture of lipids. The detected variance in lipid compositions could be related to different stages of atherosclerosis progression and factors such as diet, lifestyle and medication. These findings highlight the necessity of considering unique patient characteristics, such as medication history, when analyzing lipid profiles in atherosclerosis studies. Overall, this PhD thesis contributes to our understanding of the lipid composition in atherosclerotic plaques and highlights the potential of MALDI MSI as a valuable, powerful technique for studying macrophages and atherosclerotic plaques in murine models and human samples. The findings provide a useful basis for future research approaches and may aid in developing novel diagnostic and therapeutic strategies for cardiovascular disease.
NO-Synthasen vermitteln die cholinerge Kontrolle des P2X7-Rezeptors
(2024) Asci, Nilay
Hintergrund: Monozyten und Makrophagen sind wichtige Quellen des proinflammatorischen Zytokins Interleukin-1β (IL-1β), das an der Abwehr von Infektionen beteiligt ist. Hohe Konzentrationen dieses Zytokins werden jedoch auch mit lebensbedrohlichen systemischen Entzündungserkrankungen wie Fieber, Schock und Organschäden in Verbindung gebracht. Daher sind Mechanismen, die die IL-1β-Freisetzung kontrollieren, von erheblichem klinischem Interesse. Für die Produktion und Freisetzung von IL-1β sind zwei Hauptsignale erforderlich. Als Reaktion auf ein erstes Gefahrensignal, etwa das Endotoxin Lipopolysaccharid (LPS), das mit dem Toll-like-Rezeptor 4 (TLR-4) interagiert, wird Pro-IL-1β synthetisiert. In mononukleären Phagozyten löst extrazelluläres ATP, das aus aktivierten oder beschädigten Zellen ausgeschüttet wird, die ionotrope Funktion des P2X7-Rezeptors (P2X7R) aus, was zur Zusammensetzung des NLRP3-Inflammasoms, Aktivierung von Caspase-1, Spaltung von Pro-IL-1β in seine biologisch aktive Form IL-1β und schließlich zu seiner Freisetzung führt. Unsere Arbeitsgruppe hatte zuvor einen cholinergen Mechanismus identifiziert, der die ATP-vermittelte Freisetzung von IL-1β über nikotinische Acetylcholinrezeptoren (nAChRs) in mononukleären Phagozyten hemmt. Es wurden klassische und unkonventionelle nAChR-Agonisten identifiziert, die diese Hemmfunktion auslösen, ohne die ionotrope Funktion herkömmlicher nAChRs auszulösen. Hier untersuchten wir den Signalweg, der zur cholinergen Hemmung der ionotropen Funktion des ATP-sensitiven P2X7R führt. Methoden: Humane monozytäre THP-1-Zellen, aus THP-1-Zellen abgeleitete M1-ähnliche Makrophagen, murine mononukleäre Zellen des peripheren Blutes (PBMCs), bone marrow-derived Makrophagen (BMDMs) und humane PBMCs wurden untersucht. Mit LPS stimulierte Zellen wurden mit dem P2X7R-Agonisten BzATP oder ATP in Gegenwart von verschiedenen nAChR-Agonisten behandelt. Um die Beteiligung einer NO-Synthase (NOS) in dem oben beschriebenen Signalweg zu untersuchen, wurden die Zellen zusätzlich mit den NOS-Inhibitoren L-NAME (Nω-Nitro-L-Arginin-Methylester-Hydrochlorid) und L-NIO (L-N5-(1-Iminoethyl)-Ornithin) behandelt. Um den Effekt von NO und Peroxynitrit auf die ATP-induzierte Freisetzung von IL-1β zu untersuchen, wurde den Zellen der NO-Donor SNAP (S-Nitroso-N-Acetyl-DL-Penicillamin) oder der Peroxynitrit-Donor SIN-1 (3-Morpholinosydnonimin) zugegeben. Darüber hinaus wurden Experimente mit dem porenbildenden bakteriellen Toxin Nigericin in Gegenwart der NOS-Inhibitoren, NO- und Peroxynitrit-Donoren durchgeführt, um einen möglichen Effekt dieser Substanzen auf die ATP-unabhängige IL-1β-Freisetzung zu identifizieren. Die IL-1β-Konzentration wurde in Zellkulturüberständen mittels ELISA (enzyme-linked immunosorbent assay) ermittelt. Ergebnisse: Die hemmende Wirkung von nAChR-Agonisten auf die ATP-induzierte Freisetzung von IL-1β wurde durch die NO- und Peroxynitrit-Donoren SIN-1 und SNAP nachgeahmt und durch die NOS-Inhibitoren L-NAME und L-NIO aufgehoben. In Gegenwart von Nigericin und dem NO- bzw. Peroxynitrit-Donor SIN-1 und SNAP, konnte abhängig vom untersuchten Zelltyp ebenfalls eine Reduzierung der ATP-unabhängigen Freisetzung von IL-1β gezeigt werden. Der Effekt auf die Nigericin-induzierte IL-1β-Freisetzung war jedoch deutlich geringer als der Effekt auf die ATP-induzierte IL-1β-Freisetzung. Schlussfolgerung: Die Ergebnisse dieser Arbeit deuten darauf hin, dass die Stimulation von nAChRs zur Aktivierung einer NOS führt und dass deren Produkte NO und/oder Peroxynitrit den ATP sensitiven P2X7R inhibieren. Dieser Mechanismus lässt sich in humanen und murinen Monozyten und Makrophagen nachweisen und dürfte ein vielversprechendes therapeutisches Ziel für die zukünftige Behandlung entzündlicher Erkrankungen sein.
Moving towards Ecological Validity: Conceptions and Measurement of Children’s Musicality
(2025) Buren, Verena
Although child musicality is inherently rich and diverse, assessments often reduce it to isolated, predominantly aural abilities. This reductionist approach compromises the ecological validity of the assessments by detaching musicality from its real-world context, thereby limiting a more nuanced understanding. Reframing musicality as a social construct that is shaped by cultural conceptions of music and aesthetics addresses these limitations by acknowledging its contextual and dynamic nature. From this perspective, caregivers, educators, and music professionals can provide essential insights based on their observations of children’s musical behavior in natural contexts, ultimately deepening our understanding of musicality. This dissertation contributes to the improvement of the ecological validity of musicality assessments by integrating the perspectives of parents, educators, and music professionals. Its goal is to advance research on musical development by providing a framework that reflects the complexity of musicality. In Study 1, conceptions of child musicality (ages 3 to 6 years) were examined and compared to those of adult musicality. Study 2 focused on infants and toddlers (under 3 years of age) and explored differences in conceptions within childhood. Study 3 developed a brief screening tool that allows parents and educators to assess individual differences in children’s musicality (ages 3 to 10 years). It was grounded in a broad conception of musicality and evaluated for its psychometric properties. The results underscore the multifaceted nature of child musicality, extending beyond musical abilities (i.e., perception and production) to include enthusiasm & motivation, musical communication and analytical understanding. In infants and toddlers, musical abilities, enthusiasm & motivation and musical communication were replicated while adaptive expressiveness emerged as the fourth component, indicating age-related conceptual differences. The screening instrument based on these findings showed strong psychometric properties, indicating its potential for valid and reliable assessment of children’s musicality. This dissertation establishes an ecologically valid understanding of musicality that is informed by caregivers, educators and music professionals, who regularly observe children’s musical behavior in real-life settings. Moreover, the developed screening tool enables research into individual differences in musical development and developmental trajectories. Together, these contributions facilitate the development of additional measurement tools that better capture the complexity of children's musical behavior. This work offers practical guidance for parents and educators on how to foster musical development.
Exploring wheat wild relatives as a source of traits for drought adaptation
(2025) Pantha, Sumitra
Crop domestication and subsequent breeding have significantly enhanced global food security. However, these processes have also created genetic bottlenecks, reducing crops' genetic diversity and making them more vulnerable to environmental stresses. Crop wild relatives offer a diverse range of valuable traits, including resistance to both biotic and abiotic stresses, which can play a crucial role in enhancing food security amidst future climate change. Wheat (Triticum aestivum L. and Triticum durum Desf.) is a crucial global staple crop, vital for food and energy supply, and thus plays a key role in food security. The Triticum gene pool of wheat includes diploid, tetraploid, and hexaploid forms. Wild wheats, which are exclusively diploid or tetraploid, serve as valuable genetic resources for wheat improvement due to their evolutionary relationships with domesticated wheat. Drought-induced wheat yield losses threaten global food security and are likely to increase with climate change. Drought stress impacts plant growth and development through morphological, physiological, and biochemical changes, ultimately reducing crop yield. To address the need for resilient crops in drought-prone regions, it is crucial to identify and develop varieties that exhibit drought tolerance traits. Although, wild wheat relatives harbor vast genetic diversity for drought tolerance traits, they have not been extensively explored. Therefore, the aim of this thesis was to explore and evaluate the drought-adaptive traits of wild Triticum taxa for use in breeding drought-tolerant wheat cultivars. To evaluate drought tolerance traits in wild wheats and landraces, 110 genotypes from diverse Triticum taxa (60 wild wheats, 44 landraces and 6 modern cultivars) were evaluated at a drought-prone location with sandy loam soil at the research station of University of Giessen in Gross-Gerau during the 2021/22 winter wheat growing season. Twenty selected genotypes were further evaluated for physiological and morphological drought-adaptive traits in the same field during the 2022/23 season, and results were assessed across both years. Genotypes were selected based on their relative grain yield performance and associated physiological traits. Subsequently, a greenhouse experiment was conducted on 17 of these selected genotypes (11 wild wheats, 3 landraces, and 3 modern cultivars). This was followed by another greenhouse study focusing on 3 potential drought-tolerant genotypes from a neglected species, T. araraticum, and 2 modern bread wheat cultivars to evaluate in-depth physiological and biochemical traits that differ from modern bread wheat cultivars. These experiments were conducted under two different moisture conditions: irrigated and rainfed conditions in the field, and well-watered and drought conditions in the greenhouse experiments. In both field and greenhouse experiments, a genotype-dependent response to drought stress was observed. The Triticum gene pool showed wide variations in morphological, physiological and biochemical traits. Wild wheats such as T. dicoccoides, T. urartu and T. boeoticum exhibited isohydric stomatal regulations, while landraces and modern cultivars demonstrated anisohydric stomatal regulations. Drought stress significantly increased the accumulation of osmoprotectants, such as proline and total soluble sugars, and enhanced antioxidant activity. Additionally, T. araraticum exhibited distinct drought tolerance via glutathione (GSH) redox balance, marked by enhanced enzymatic activities like monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR). In contrast, modern bread wheat cultivars showed enhanced ascorbate (AsA) redox in response to drought stress. Four drought-tolerant candidates have been selected from this study across four different taxa: three from wild and one from a landrace. These candidates can be used as pre-breeding sources for wheat improvement. Modern breeding techniques could be employed to incorporate drought-tolerant candidates into breeding program.
Comparative ecology of sympatric storm-petrels: Breeding biology, niche segregation, and response to environmental changes
(2025-05) Bedolla Guzmán, Yuliana Rocío
Seabirds, including storm-petrels, are integral to marine ecosystems, yet significant gaps persist in understanding their ecology. This PhD thesis examines the niche segregation, breeding biology, and responses to environmental variability of three sympatric storm-petrel species: Leach’s storm-petrel (Hydrobates leucorhous), which is widely distributed across the Atlantic and Pacific Oceans, and the black storm-petrel (Hydrobates melania) and least storm-petrel (Hydrobates microsoma), both restricted to the Eastern Tropical Pacific. These species breed in sympatry on the San Benito Archipelago, Mexico, which supports a population of approximately two million individuals. The thesis aims to advance knowledge of their resource use, reproductive strategies, and adaptive responses to environmental changes, addressing critical gaps in their ecological understanding. The research is structured into three chapters, each exploring distinct ecological aspects. Chapter 1 evaluates niche segregation among the three storm-petrel species using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) from tissues such as blood, feathers, and egg membranes, along with diet samples collected in 2012–2013. A marine isoscape was constructed using krill samples from the Pacific waters off Baja California. The findings demonstrated significant dietary and isotopic niche segregation during the breeding season, with black storm-petrels consuming high-trophic-level krill from neritic waters, while Leach’s and least storm-petrels fed on lower-trophic fish larvae in oceanic regions. Additionally, black storm-petrels exhibited shifts in foraging strategies across breeding phases, reflecting dietary flexibility. Chapter 2 focuses on the breeding biology of the least storm-petrel, investigating breeding phenology, reproductive success, chick growth, and diet over three breeding seasons (2013–2015). Eggs, chicks, and adults were monitored, and diet samples were collected to evaluate feeding ecology. Morphometric differences between sexes were analyzed using mist-net captures and molecular sexing in 2012. Results revealed consistently high breeding success, with inter-annual variations in timing of breeding and chick growth linked to anomalous climate conditions. Females exhibited longer wings and tails than males, while dietary analyses identified larval fish, euphausiids, and squid as key prey items. Chapter 3 investigates inter-annual variability in the breeding biology, chick growth, and provisioning behavior of the black storm-petrel over six consecutive breeding seasons (2012–2017). Parameters such as peak mass, fledging mass, feeding rate, and meal size showed significant inter-annual variation, although these trends were not explained by regional or local environmental indices. This suggests that other factors such fine-scale habitat or pre-breeding ocean conditions may play a more influential role in shaping these reproductive traits. In conclusion, this thesis provides valuable insights into the resource partitioning, breeding biology, and adaptive strategies of storm-petrels, highlighting the importance of niche segregation in facilitating coexistence and reducing interspecific competition. The results emphasize the need to account for environmental variability and anthropogenic pressures in conservation strategies. By contributing to a broader understanding of storm-petrel ecology, this work establishes a foundation for enhancing conservation and management efforts for these and other seabird species in dynamic and rapidly changing marine ecosystems.
The Intersection of CSR, Contextual Factors, and Executive Incentives
(2024) Höhre, Andreas
This dissertation consists of three essays, each exploring how corporate social responsibility (CSR) is operationalized in businesses through the application of environmental, social, and governance (ESG) criteria. Across these essays, CSR and executive incentives are analyzed from multiple perspectives.
Einfluss des Musters in der konfokalen Endomikroskopie (pCLE) auf den Langzeit-Verlauf bei Patienten mit interstitiellen Lungenerkrankungen
(2024) Hamberger, Daniel
In der vorliegenden Arbeit erfolgte ein Follow-up zur Arbeit von Silbernagel et al. bei der therapienaive Patienten vor Diagnostik einer ILD mittels pCLE untersucht wurden. Die pCLE ist ein experimentelles endoskopisches Verfahren zur Darstellung von alveolären Strukturen und hat damit einen möglichen therapeutischen Nutzen bei der ILD. Von insgesamt 39 Patienten der damaligen Studienpopulation konnten durch Kontaktaufnahme mit Fach- und Hausärzten Verlaufsdaten über Lungenfunktion und Krankheitsverlauf inklusive Mortalität gesammelt werden. Aus diesen Daten wurde eine Korrelation zwischen den pCLE-Mustern und der Abnahme der Lungenfunktion hergestellt. Auch der Einfluss des pCLE-Musters auf die Mortalität wurde untersucht. Dabei zeigt sich, dass die Abnahme der Lungenfunktion in den ersten 6 Monaten nach der Untersuchung signifikant mit dem Ausmaß der Gewebszerstörung korreliert. Die Gewebszerstörung ist außerdem überwiegend bei den fibrosierenden Erkrankungen zu finden. Der Nachweis von Alveolarmakrophagen scheint insgesamt prognostisch günstig zu sein, da sich eine deutlich niedrigere Mortalität abzeichnet, auch wenn die Lungenfunktion im Verlauf nicht signifikant davon abhängt. Alveolarmakrophagen werden dabei in der pCLE überwiegend bei nicht-fibrosierenden Erkrankungen nachgewiesen, die eine bessere Prognose aufweisen. Aufgrund der kleinen Studienpopulation und der im Beobachtungszeitraum zunehmenden Mortalität sind die Ergebnisse in ihrer Aussagekraft deutlich eingeschränkt. Es werden daher Studien mit größeren Studienpopulationen benötigt, um einen prognostischen Marker bei ILDs mittels der pCLE zu finden. In der vorliegenden Arbeit ist das pCLE-Muster Distorsion signifikant mit der Krankheitsprognose assoziiert.
Veränderung auditiv-subjektiver und objektiv-apparativer Stimmparameter vor und nach phonochirurgischen Eingriffen bei gutartigen Stimmlippenveränderungen – eine retrospektive Datenerhebung
(2025) Heine, Fabienne
Das Ziel dieser Arbeit war die, in Anlehnung an das Basis-Protokoll der ELS, multidimensionale Untersuchung der Stimmqualität zur Beurteilung einer Stimmverbesserung nach phonochirurgischer Intervention bei gutartigen Stimmlippenerkrankungen in einem Patientenkollektiv an der HNO-Universitätsklinik in Magdeburg. Hierfür wurden die Daten von 51 Patienten, die sich im Zeitraum von 2014 bis 2020 aufgrund einer Stimmstörung in operativer Behandlung befanden, ausgewertet. Es zeigte sich in der Gesamtgruppe eine signifikante Verbesserung sowohl der objektivapparativen, als auch der auditiv-subjektiven Stimmparameter. In den histologischen Subgruppen konnten für die Reinke-Ödeme und Polypen signifikante Ergebnisse erzielt werden, tendenzielle Verbesserungen zeigten sich auch in den anderen Subgruppen. Folglich scheint die operative Therapie gutartiger Stimmlippenveränderungen mittels Mikrolaryngoskopie nicht nur für den Operateur ein zufriedenstellendes Ergebnis zu erzielen, sondern auch für den Patienten, dessen Leidensdruck gesenkt und Lebensqualität gesteigert werden kann. Ähnliche Ergebnisse konnten auch in anderen Studien gefunden werden, um jedoch eine bessere Vergleichbarkeit zu schaffen, wäre die Vereinheitlichung der Stimmdiagnostik wünschenswert. Bei der epidemiologischen Auswertung des untersuchten Patientenkollektivs zeigten sich Reinke-Ödeme signifikant häufiger bei Frauen, während Polypen häufiger bei Männern zu finden waren. Rauchen als Risikofaktor bei der Entstehung von Reinke-Ödemen konnte bestätigt werden. Zusammenfassend ermöglicht die mikrolaryngoskopische Therapie von benignen Stimmlippenpathologien eine rasche Symptombesserung, wichtig in diesem Zusammenhang ist aber auch die Kontrolle der Risikofaktoren für einen anhaltenden Erfolg.
Anwendung und Weiterentwicklung der Ionenstrahlsputterdeposition : Entkopplungsansätze für eine nachhaltige Dünnschichtabscheidung
(2025) Benz, Sebastian Leonard
Für die Speicherung, Einsparung, den Transport und die Nutzung von Energie existieren zahlreiche etablierte Lösungen, bei denen funktionale Dünnschichten häufig eine zentrale Rolle spielen. Viele dieser Technologien beruhen jedoch auf fossilen Energieträgern oder dem Einsatz kritischer Materialien. Die vorliegende Arbeit widmet sich daher der Ionenstrahlsputterdeposition im Kontext von Substitutionsmaterialien für nachhaltige Energietechnologien. Diese Methode zur Abscheidung funktionaler Dünnschichten wurde zunächst dafür genutzt, neuartige Heterostrukturen zu synthetisieren. Mithilfe von Röntgenphotoelektronenspektroskopie wurden diese Heterostrukturen hinsichtlich ihrer Eignung für sogenannte All-Oxide-Dioden untersucht. Dabei wurden die Banddiskontinuitäten der erzeugten pn-Übergänge bestimmt und miteinander verglichen. Da ausschließlich Metalloxide verwendet werden, verspricht der All-Oxide-Ansatz den Einsatz leicht verfügbarer, nachhaltiger Materialien. Darüber hinaus wurde die Ionenstrahlsputterdeposition eingesetzt, um die Metalllegierung NiCr8020 mit niedrigem Temperaturkoeffizienten abzuscheiden. Diese Legierung findet Anwendung in Bauteilen zur präzisen Strommessung über große Temperaturbereiche – etwa in Batteriesystemen für die Elektromobilität. Es konnte gezeigt werden, dass sich der Temperaturkoeffizient durch Modulierung der Prozessparameter bei der Ionenstrahlsputterdeposition effektiv kontrollieren lässt. Im weiteren Verlauf wurde die Ionenstrahlsputterdeposition selbst optimiert. Ziel war es, durch gezielte Modifikationen des Wachstumsapparats, die Abscheiderate zu erhöhen, ohne die Schichtqualität zu beeinträchtigen. Hierzu wurden Metalloxidschichten abgeschieden und mittels Röntgenphotoelektronenspektroskopie, Rasterkraftmikroskopie, Ellipsometrie, Röntgenbeugung und -reflektometrie umfassend charakterisiert. Es zeigte sich, dass durch die räumliche Entkopplung von Inert- und Reaktivgas sowohl die Depositionsrate als auch die Schichtqualität signifikant verbessert werden konnten. Abschließend wurden die Wachstumsprozesse in-situ mittels optischer Emissionsspektroskopie analysiert. Unter Anwendung eines collisional radiative models konnte die lokale Dichte atomaren Sauerstoffs für verschiedene Reaktivgaseinlasspositionen quantifiziert werden. Die Untersuchungen führten zu einem tieferen Verständnis des Prozesses und erlaubten die Entwicklung eines vereinfachten, kostengünstigen Spektrometers. Dieses ermöglicht es, den Wachstumsprozess effizient zu überwachen und Ausschuss durch rechtzeitigen Abbruch zu vermeiden.
Reconstruction of the Sigma0 baryon in Ag+Ag collisions at sqrt(s_NN) =2.55 GeV with HADES
(2025) Becker, Marten
This work presents the experimental reconstruction of the Sigma0 baryon in – with respect to NN interactions – subthreshold Ag+Ag collisions at 1.58 AGeV kinetic beam energy measured with the HADES experiment. At the HADES experiment, which is located at GSI in Darmstadt, Germany, heavy ion collisions at moderate freeze-out temperatures and high baryon chemical potential are measured, analyzed, and evaluated in comparison with the existing data as well as theoretical predictions. This kinetic beam energy corresponds to a center of mass energy of sqrt(s_NN) = 2.55 GeV, which is the Lambda baryon production threshold in NN collisions. With only a small mass difference of Sigma0 to the Lambda baryon of 77 MeV/c^2, Sigma and Lambda baryons are the lightest strangeness containing baryons. Since all quantum numbers of the Sigma0 and the Lambda baryon are identical, their production mechanisms are expected to be very similar. Due to a different spin configuration of the valence quarks inside the Sigma0 , the Sigma0 is slightly more heavy and decays with nearly 100 % branching ratio into Lambda-photon. However, the reconstruction of the low-energy photon is challenging for most detectors, particularly when attempting to concurrently satisfy the requirements of Lambda reconstruction. For the beamtime of the analyzed Ag+Ag collisions, 15 billion events were recorded. The newly installed electromagnetic calorimeter enables photon reconstruction for HADES for the first time without relying on the previously used conversion method. Within the 0-40 % most central events, around 8000 Sigma0 baryons were reconstructed in the Lambda-photon channel with a significance of approximately 10. In addition to the newly installed electromagnetic calorimeter, the RICH was upgraded with newmulti-anode photomultipliers which strongly enhance reconstruction efficiency as well as lepton purity. These advantages were used for feasibility studies in the Lambda-e+e− decay channel. Hints for a signal were found that are consistent with the extracted signal from the Lambda-photon channel, but due to the small statistics, only a significance level of less than 3 was achieved. A full efficiency and acceptance correction was performed with a resulting multiplicity of 0.014 ± 0.002stat. ± 0.004sys. produced Sigma0 per event which corresponds to a Lambda/Sigma0 ratio at freeze-out of 3.2 ± 0.3stat. ± 0.6sys.. This represents the first measurement of this ratio for a subthreshold Sigma0 production in nucleus nucleus collisions. Comparing to the available world data of p+p collisions close to the Sigma0 production threshold, this ratio increases in p+p to values of 30 and higher. Even more, the measured ratio compares well to measurements in p+p far from threshold. This indicates that the NN threshold has no influence on the Sigma0 production for this energy. The Lambda-photon channel result is compared to statistical hadronization model fit as well as to several transport model predictions. The statistical model calculations are in good agreement to our measurement which endorses the possibility of hyperon production in a thermally equilibrated medium. In this case, the freezeout ratio is directly connected to the mass difference of two states with the same quantum numbers, resulting in a temperature estimation of the created matter by only measuring Lambda and Sigma0. From these measurements T=66 MeV is extracted, which compares well with fits of all hadrons with a statistical model.
Einfluss des PVS als Vorlastparameter auf den linksventrikulären Strain und die Auswirkung auf dessen prognostische Vorhersagekraft
(2024) Okanovic, Lejla
Die Strainanalyse ist ein diagnostisches Tool zur Bestimmung der kardialen Deformation während eines Herzzyklus und bewertet die Kontraktilität des Myokards. Das Herz de-formiert sich aufgrund seines anatomischen Aufbaus in longitudinaler, zirkumferentieller und radialer Richtung. Analog dazu lassen sich drei Strain-Parameter der kardialen De-formation ableiten. Regulationsmechanismen der Kontraktilität sind die Kraft- Spannungsbeziehung (=Frank-Starling-Mechanismus), die Kraft-Frequenz-Beziehung (=Bowditch- Effekt) und die sympatho-adrenerge Aktivierung. Der Frank-Starling-Mechanismus beschreibt den Zusammenhang zwischen Füllungsvolumen des Ventrikels und Auswurfleistung des Herzens. Mit zunehmender enddiastolischer Füllung steigt die Vordehnung des Herzmuskels und damit die Kontraktilität der Muskelfaser (14). Ziel dieser Arbeit war es zu überprüfen, ob eine Zunahme der enddiastolischen Füllung, die Kontraktilität steigert und damit die Strainanalyse beeinflusst. Des Weiteren sollte analysiert werden, ob der PVS neben dem Einfluss auf den linksventrikulären Strain, auch Einfluss auf dessen prognostische Vorhersagekraft hat.
Identification of Key Players of the Ecdysteroid Pathway and Detection of Ecdysteroid Synthesizing Tissues in Chelicerates : Insights into the Evolution of Molting in Panarthropoda
(2025-07) Klinkenbuß, Denise
Ecdysteroids are crucial hormones that regulate molting and developmental progression in arthropods. While the biosynthesis pathway of these hormones has been extensively studied in insects, functional characterization of the involved components remains limited in chelicerates. This thesis focuses on the early-to-late ecdysteroid pathway genes neverland (Pt-nvd, Rieske-domain oxygenase), shroud (Pt-sro, short-chain dehydrogenase/reductase), the cytochrome P450 genes spook (Pt-spo), disembodied (Pt-dib), shadow (Pt-sad) and shade (Pt-shd) as well as the ecdysteroid-inactivating CYP18A1 (Pt-CYP18A1) in the spider Parasteatoda tepidariorum. The aim is to evaluate functional conservation and potential evolutionary diversifications within these molting-related gene families beyond Pancrustacea. Single-cell RNA sequencing analyses combined with whole-mount in situ hybridizations reveal common expression domains in mid-embryonic hemocytes for Pt-nvd, Pt-sro, Pt-spo, Pt-dib, Pt-shd and Pt-CYP18A1, and a later shift to the cardiac vessel or its lumen for Pt-nvd, Pt-sro, Pt-dib, Pt-sad, and Pt-CYP18A1 during late embryogenesis. Pt-sad additionally marks neuroectodermal precursors, implicating a function in early neurogenesis. Parental RNA interference against Pt-sad disrupts head lobe formation, significantly elevates embryonic lethality and interval until first ecdysis. This indicates essential roles of the gene in both endocrine and morphogenetic processes. Juvenile knockdowns of all studied genes drastically extend molt intervals (up to four-fold) and produce lethal molting defect phenotypes, confirming pathway conservation at the functional level. As in insects, postembryonic expressions of Pt-nvd, Pt-sro, Pt-spo, Pt-dib and Pt-sad are localized in a common tissue during postembryonic stages. However, instead of a centralized prothoracic gland, spiders appear to utilize hemocytes for ecdysteroidogenesis. The findings establish hemocytes as previously unrecognized ecdysteroid pathway domains in spiders and reveal spider-specific involvement of shadow in neurogenesis. Thereby, this work provides some of the first evidence for ecdysteroid pathway activity in chelicerates, reinforcing functional pathway conservation across panarthropods while exposing evolutionary flexibility of endocrine regulation.
Syntheses and investigations of metal complexes with tripodal and macrocyclic ligands
(2025) Schneider, Lars
This dissertation focuses on developing metal complexes, particularly copper complexes, for activating oxygen and/or hydrogen peroxide.
The first part focuses on the tripodal ligand imine3tren (tris(2-(propan-2-ylideneamino)-ethyl)amine), which was used to confirm the crystalline structures of various metal complexes, including zinc, nickel, sodium, and copper complexes. However, the formation of a copper-dioxygen intermediate could not be confirmed.
The second part is about the macrocyclic ligand (tBu)2(nPrSO3)Htacn, which has a higher water solubility due to its sulfonic acid group. The formation of copper dioxygen intermediates were confirmed with dioxygen in aprotic solvents and with hydrogen peroxide in protic solvents. Based on kinetic investigations, a mechanism for the formation of a copper-dioxygen intermediate in water was established.

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