Why grasses grow better after drought: Mechanisms driving post-drought recovery and productivity outperformance in temperate grasslands

Despite 2023 being with a 1.4 K higher global surface temperature compared to the 1850-1900 average the warmest year ever recorded, it will likely once be among the coldest years measured in this century. According to the Intergovernmental Panel on Climate Change, the increase in earth’s surface temperature will reach 1.4 K to 4.4 K compared to the 1850-1900 reference period by 2100, depending on the future emission scenario. With every temperature increment, the capacity and demand of the atmosphere to hold water increases. Increased amounts of water vapor in the atmosphere will affect large-scale atmospheric circulation processes and ultimately lead to more frequent extreme climatic events such as drought. Drought has been a common threat to terrestrial ecosystems. Nonetheless, the projected increase in its frequency and intensity will doubtlessly transform our ecosystems and pose new challenges to human societies. Yet, certain ecosystems seem to cope better with drought than others. Some grasslands have a remarkable capacity to regrow after drought with formerly drought-stressed grasslands even outperforming non-stressed controls once drought is released. The processes and factors underlying this capacity have, however, not yet been identified. In this PhD thesis, I delve into drought recovery mechanisms in temperate perennial grasslands and identify the key drivers that lead to post-drought outperformance in plant aboveground productivity

Large vessel vasculitis in giant cell arteritis and polymyalgia rheumatica – prevalence, outcome and associated factors

Background: Giant cell arteritis (GCA) is the most common primary vasculitis of the elderly and is closely related to polymyalgia rheumatica (PMR). Both conditions may occur separately, simultaneously, or sequentially over time. GCA classically manifests as cranial arteritis, but large vessel vasculitis (LVV) has been recognized as part of the disease spectrum. Diagnosing LVV remains challenging as symptoms may be non-specific and imaging is necessary to establish the diagnosis. Furthermore, PMR may be the only clinical manifestation of GCA. However, the understanding of subclinical GCA in patients with PMR, including its prevalence, risk factors and prognostic significance, is limited. GCA is associated with severe vascular and ischemic complications such as stroke, arterial stenosis, and the development of aortic aneurysms. The most feared complication of GCA is permanent vision loss, and timely diagnosis and treatment of GCA are crucial to prevent acute and chronic complications. Although fast-track clinics for GCA have reduced the delay in diagnosis, permanent vision loss is still reported in up to 13% of cases. Established imaging modalities for the diagnosis of LVV include ultrasound, [18F]fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT), CT, or magnetic resonance imaging (MRI). However, standardized criteria defining vasculitis on MRI are lacking. While imaging is well established in the diagnostic work-up of patients with suspected GCA, its role in monitoring disease activity during follow-up and predicting the disease course in GCA after treatment discontinuation remains unclear. As relapses are common in patients with GCA after treatment withdrawal, imaging biomarkers for guiding the timing of treatment stop would be helpful. Objectives: We first aimed to investigate the prevalence of subclinical GCA in patients with newly diagnosed PMR in the literature and to identify potential patient characteristics associated with subclinical GCA in published cohorts. In a next step, we aimed to explore the hypothesis that undiagnosed subclinical GCA in patients with PMR may lead to GCA-associated vascular damage. In our second manuscript, we aimed to study the risk factors and incidence of permanent vision loss in patients with GCA and to identify obstacles which caused a delay in diagnosis. The third manuscript aimed to identify which parameters on MRI correspond to vasculitis in patients with newly diagnosed large vessel (LV-) GCA. Finally, we addressed the role of PET/CT and MRI to predict relapses after treatment stop in patients with large vessel LV-GCA. Methods: We systematically searched PubMed, Embase, and Web of Science Core Collection for consecutively recruited cohort studies reporting the prevalence of GCA in steroid-naïve patients with PMR. Potential predictors of subclinical GCA were identified using individual patient data from seven cohorts. In the frame of our retrospective cohort of patients with GCA, we investigated the hypothesis that a proportion of patients with newly diagnosed GCA and a history of PMR may have already had subclinical GCA at the time of PMR manifestation and compared vascular ultrasound findings (extent of vessel involvement and stenoses) between GCA patients with and without prior PMR. Furthermore, we used our retrospective cohort to examine patient and referral characteristics and trends in the incidence of permanent vision loss over the past 15 years at the University Hospital Basel. To identify which parameters on MRI correspond to vasculitis in patients with newly diagnosed LV-GCA, we compared MRI findings to PET/CT and/or ultrasound findings on a segment level (axillary segment per side, and the thoracic aorta). Lastly, in an exploratory cohort study, patients with LV-GCA underwent imaging at the time of treatment discontinuation. Imaging findings of patients who relapsed within 4 months after treatment discontinuation were compared to those who remained in remission. Results: The pooled prevalence of subclinical GCA across all identified studies was 23%, and 29% in the studies using PET/CT. Inflammatory back pain and absence of lower limb pain remained weak predictors of subclinical GCA after multivariable analysis. Newly diagnosed patients with GCA and a prior history of PMR had significantly more often LVV (51.0% vs. 25.0%, p<0.001) and stenosis within the vasculitic segments (18.4% vs. 3.1%, p<0.001) on ultrasound compared to patients without prior PMR in our retrospective cohort. The incidence of permanent vision loss was 17.4% in our institution and did not decline over 15 years. More than half of the patients who suffered from vision loss had experienced non-ocular symptoms related to GCA for a median of 21 days but did not seek medical help until the onset of visual impairment. In multivariable analysis, patients with vision loss were older and reported more frequently jaw claudication. Vessel wall oedema on diffusion-weighted sequences on MRI corresponded to vasculitic PET/CT findings while pathological vessel segments on MRI had a low agreement with vasculitic ultrasound findings. None of the examined imaging parameters predicted subsequent relapse after treatment withdrawal in patients with LV-GCA. The number of segments with vasculitic findings on PET/CT and the sum of all maximum standardized uptake value (SUVmax) artery/liver ratios showed a slight tendency to be higher in patients who relapsed; however, this did not reach statistical significance. Conclusion: The high prevalence of subclinical GCA and the accumulating evidence of the potential impact of subclinical GCA on disease outcome advocates a paradigm shift in the assessment of patients with PMR and supports the implementation of screening strategies for large vessel involvement. Our findings underscore the need to increase public and physician awareness of the potentially devastating consequences of GCA and the importance of early detection and timely medical treatment to further reduce the incidence of ischemic and vascular complications. Lastly, we did not find any parameter on imaging performed at the time of treatment discontinuation which predicted future relapse in patients with LV-GCA. The relevance of vasculitic imaging findings in patients in clinical remission of GCA for the development of aortic aneurysms should be further studied

Mycorrhiza within intercropping systems: Exploring AMF mediated complementary effects across staple crops from the drylands

The main aim of this thesis was to advance the ecological know-how for the effective use of AMF within intercropping systems, aiming to optimize complementary interactions between crops. In the first chapter of the thesis, I tested AMF-based biofertilizers in field trials in southern India. There, I examined how biofertilizers influenced intercropping performance across different spatial arrangements and crop mixtures across different sites. In the second chapter, I conducted greenhouse experiments where I tested the efficiency of AMF mediating complementary effects under increasing nutrient availabilities as well as different crop mixtures. In the third chapter, I tested the relevance of planting distance mediating interspecific water transfer by one AMF strain from deep-rooted legumes to shallow rooted cereals during drought

Disentangling Chemical Interaction and Electric Fields at Electrochemical Interfaces

The specific binding of solution components to a catalytic surface and the interfacial electric field are critical to electrocatalysis, but the two factors are entangled. Distinguishing whether adsorbate binding to the surface is governed by through-bond charge transfer that is modulated by a field or through-space electrostatic effects is essential for rational catalyst design. Here, we probed the binding of thiocyanate (SCN–) to Au and Pd as a function of applied potential (ϕapp) using surface-enhanced infrared absorption spectroscopy (SEIRAS). The IR data showed distinct shifts of the CN stretching wavenumbers (ν̃CN) with ϕapp for S- versus N-bound SCN– and on Au versus Pd. These ν̃CN shifts with ϕapp are the result of different extents of through-space electric field (Stark) effects and through-bond chemical binding effects. The presence of two binding modes of SCN– on the metal surfaces provided two separate interfacial probes, which enabled estimating the contributions of the two effects to the overall ν̃CN versus ϕapp slopes quantitatively. Competitive adsorption experiments using SCN– and different halides (Cl–, Br–, and I–) support our conclusions. While the through-bond effect for S-bound SCN– is more pronounced on Pd than on Au, that of N-bound SCN– is similar. Our data also suggest a similar electric field change with ϕapp on Pd and Au. This work offers a method to differentiate key contributors to interfacial chemistry in an external electric field and provides important groundwork for the development of future electrocatalysts

Bioanalysis and metabolic investigation of psychoactive substances

In Part I, four liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods for the bioanalysis of psychoactive substances and their metabolites were developed and validated according to United States Food and Drug Administration (FDA) guidelines. The first method was validated for the quantification of mescaline and its metabolites 3,4,5-trimethoxyphenylacetic acid (TMPAA), N-acetyl mescaline (NAM), and 3,5-dimethoxy-4-hydroxyphenethylamine (4-desmethyl mescaline). A linear range of 12.5 to 5,000 ng/mL for mescaline and TMPAA, and 1.25 to 500 ng/mL for NAM and 4-desmethyl mescaline was achieved. For optimal chromatographic separation, an Acquity Premier HSS T3 C18 column was employed. A single-step extraction procedure was implemented, enabling a non-laborious analysis of plasma samples with a runtime of 4.25 minutes per sample. The method satisfied all FDA validation criteria, including those on accuracy (85–106%), precision (coefficient of variation [CV] ≤ 7%), sensitivity and selectivity, matrix effect (92–100%), and extraction recovery (≥ 98%). Ultimately, the method was successfully employed for the analysis of mescaline, TMPAA, and NAM in pharmacokinetic samples from participants enrolled in a clinical phase I study. 4-desmethyl mescaline could not be selectively analyzed in pharmacokinetic samples due to interference and incomplete chromatographical separation with another metabolite, presumably 3,4-dimethoxy-5-hydroxyphenethylamine (3-desmethyl mescaline). The second method was developed for the analysis of pharmacokinetic parameters in plasma samples from a clinical study involving diamorphine-dependent patients. The objective of the study was to investigate the feasibility of intranasal diamorphine administration as a component of diamorphine-assisted treatment. Analytes were separated using a Kinetex EVO C18 analytical column. The method is capable of quantifying the concentrations of diamorphine, 6-monoacetylmorphine (6-MAM), morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) in human plasma, spanning a linear range of 1 to 1,000 ng/mL. The total runtime for a single sample was four minutes. The method was demonstrated to be accurate (91–106%) and precise (CV ≤ 9%) while exhibiting a high extraction recovery (> 87%) and a negligible matrix effect (99–125%) for all analytes. No interferences with endogenous plasma compounds were observed and the method was successfully applied for the analysis of numerous clinical study samples. In the third project, two methods for the quantification of racemic and chiral 3,4-methylenedioxymethamphetamine (MDMA) and its metabolite 3,4-methylenedioxyamphetamine (MDA) in human plasma were developed and validated. A linear range of 0.5–500 ng/mL was achieved for racemic MDMA and MDA analysis, while linear ranges of 0.5–1,000 ng/mL and 1–1,000 ng/mL were achieved for chiral MDMA and MDA, respectively. The achiral chromatographic separation of the compounds was performed using a Luna PFP(2) column and the chiral analysis was conducted with a Lux AMP column. The total run times were 4.25 and 6 minutes for achiral and chiral sample analysis, respectively. Both methods met the FDA validation guidelines criteria for accuracy, precision, selectivity, sensitivity, matrix effect, and extraction recovery. Finally, a subset of clinical plasma samples from a study involving R-, S-, and racemic MDMA was analyzed to demonstrate the method’s functionality. In conclusion, four sensitive, non-laborious, highly reliable, and robust LC–MS/MS methods for the bioanalysis of mescaline, diamorphine, racemic MDMA, and chiral MDMA plus their respective metabolites were developed and validated. These methods are applicable in pharmacokinetic investigations in a clinical setting as well as for forensic studies. Part II of this thesis presents an investigation of the metabolic pathways of psilocybin’s active metabolite psilocin. The primary focus was on the phase I metabolism of psilocin through the cytochrome P450 (CYP) system, as well as the influence of monoamine oxidases (MAOs). Phase II metabolism, with a particular focus on UDP-glucuronosyltransferases (UGTs), was also examined. To conduct a comprehensive analysis of psilocin’s metabolism, enzymatic in vitro assays were performed using human liver microsomes (HLM) and recombinant CYP, MAO, and UGT enzymes. Moreover, plasma samples from C57BL/6J mice and humans were analyzed following psilocybin administration to obtain in vivo data. After a 4-hour incubation period, approximately 29% of psilocin was metabolized by HLM. Recombinant CYP2D6 and CYP3A4 enzymes demonstrated even higher metabolic activity, with nearly 100% and 40% of psilocin being metabolized, respectively. The metabolites 4-hydroxyindole-3-acetic acid (4-HIAA) and 4-hydroxytryptophol (4-HTP) were identified in the presence of HLM, but not after incubation of psilocin with recombinant CYP enzymes. Nevertheless, trace amounts of 4-HIAA and 4-HTP were generated by MAO-A from psilocin, thereby substantiating its involvement in this metabolic pathway. In contrast to the in vivo data, where conjugated psilocin is one of the main metabolites, UGT1A10 did not extensively conjugate psilocin in vitro. Furthermore, two potential metabolites were identified. In vitro and in vivo analyses identified N-methyl-4-hydroxytryptamine (norpsilocin) and an oxidized metabolite of psilocin. The former was detected following incubation with CYP2D6 and in the plasma of mice, while the latter was identified in CYP2D6 incubations, in mice, and in humans. However, the investigation into the influence of the CYP2D6 genotype on psilocin degradation yielded no significant results. While norpsilocin has never been described as a psilocin metabolite in mice before, the exact structure of the oxidized metabolite remains to be elucidated. In conclusion, the phase I enzymes CYP2D6, CYP3A4, and MAO-A are implicated in psilocin’s metabolism. The identification of putative norpsilocin in mice and oxidized psilocin in humans offers further insight into the metabolic pathway of psilocybin and could contribute to the safety and efficacy of psilocybin application

TBX3 restricts anterior gene expression from the posterior mesenchyme to protect posterior identity that is promoted by HAND2

Embryonic development and organogenesis depend on precise spatial and temporal control of gene expression, which is regulated by cis-regulatory modules (CRMs). The signalling pathways and transcription factors form a robust gene regulatory network (GRN) to control growth and cell differentiation patterns. The establishment of limb anterior-posterior (A-P) polarity requires the genetic interaction between Tbx3, Hand2, and Gli3. The interaction involves posterior Tbx3 working with Hand2 to genetically antagonise Gli3. This results in the segregation of an anterior-distal Gli3 and a posterior Hand2 and Tbx3 signal. This distinction in A/P patterning will control other transcription factors and establish early A/P polarisation. Hand2 and Tbx3 are required to prevent posterior expansion of Gli3 expression in early limb buds and maintain posterior gene expression. Hand2 has been shown to be important for ulna and autopod formation; in the absence of Hand2, the ulna is completely lost, leaving only a digit that appears to develop independently of SHH signalling. Meanwhile, the deletion of Tbx3 in the limb results in the loss of digit 5 and a mild downregulation of posterior gene expression. Hand2 and Tbx3 maintain each other's expression; deletion of Hand2 results in complete loss of posterior Tbx3, whereas mutation of Tbx3 leads to downregulation of Hand2. How Tbx3 and Hand2 restrict Gli3 expression and the observed differential roles of Tbx3 and Hand2 in maintaining posterior gene expression remain to be elucidated. Here, we have identified the role of posterior TBX3 in restricting anterior gene expression in the posterior. In doing so, TBX3 supports HAND2 in promoting posterior gene expression, setting the stage for Shh to be properly expressed. TBX3 binds to three out of four Gli3 enhancers active in the limb, whereas Hand2 only binds to one. This suggests that TBX3 may be essential to exclude the high expression of Gli3 in the posterior limb buds. Indeed, our results show that mutation of Tbx3 leads to an expansion of the Gli3 enhancers mm1179 and mm-hs1586 activity in the posterior limb buds. TBX3 binds several CRMs associated with anterior genes. We propose that TBX3, by interacting with CRMs of anterior gene, would restrict Irx3/5, Alx4, and Hand1 expression and exclude from the posterior limb bud. We've also investigated the anterior role of Tbx3 using the genetic interaction between Tbx3 and Gli3. As reported in previous studies, Tbx3 cooperates with Gli3 to restrict digit 1 development and prevent preaxial polydactyly (PPD). The combined mutation of Tbx3 and heterozygous Gli3 increases PPD. Observations of the Hand2-Tbx3 combined mutants versus Gli3-Tbx3 and our late-stage HCR data highlight a digit 1 development that relies only on anterior Tbx3 and Gli3 but would be independent of Hand2. Since Tbx3 has been shown to play a role in both anterior and posterior limb development, the mild downregulation of posterior genes seen in a Tbx3 mutant may be due to a buffering effect caused by the deletion of anterior and posterior Tbx3. TBXs would also play a role in promoting Gli3 expression, as deletion of the T-box binding motif resulted in a partial loss of spatial Gli3 enhancer activity. By examining the literature and TBXs gene expression concerning Tbx3 mutation, we propose that TBX15, TBX18 and TBX5 could be candidates for the activation and promotion of Gli3 expression in the mouse limb bud. Interestingly, Tbx15 expression largely overlaps with Gli3 and extends to the posterior mesenchyme in Tbx3 deficient limb buds. On the other hand, TBX5 shares phenotypic limb changes and binds Gli3 enhancers, which suggests that TBXs may function in maintaining Gli3 enhancer activities and expression, which raises new questions about how TBXs might compete to regulate the expression of shared target genes

Substrate adaptors are flexible tethering modules that enhance substrate methylation by the arginine methyltransferase PRMT5

Protein arginine methyltransferase (PRMT) 5 is an essential arginine methyltransferase responsible for the majority of cellular symmetric dimethyl-arginine (SDMA) marks. PRMT5 uses substrate adaptors such as pICln, RIOK1, and COPR5, to recruit and methylate a wide range of substrates. Although the substrate adaptors play important roles in substrate recognition, how they direct PRMT5 activity towards specific substrates remains incompletely understood. Using biochemistry and cryogenic electron microscopy (cryo-EM), we show that these adaptors compete for the same binding site on PRMT5. We find that substrate adaptor and substrate complexes are bound to PRMT5 through two peptide motifs, enabling these adaptors to act as flexible tethering modules to enhance substrate methylation. Taken together, our results shed structural and mechanistic light on the PRMT5 substrate adaptor function and the biochemical nature of PRMT5 interactors

Design and evaluation of bioinspired lipid nanoparticles for optimized gene therapy

Gene therapy offers the possibility to prevent and treat numerous diseases, thereby improving the well-being of millions of individuals. The success of such treatments requires efficient delivery of nucleic acids to cells. For this, various gene delivery strategies, including modified oligonucleotides, viruses, and lipid nanoparticles (LNPs), have been widely explored and used in clinical practice. LNPs have demonstrated their effectiveness with the success of the messenger ribonucleic acid vaccines from Pfizer-BioNTech and Moderna against the coronavirus disease 2019. However, despite this monumental achievement, the LNP technology still faces challenges, including limited efficacy and potency, safety concerns, and regulatory considerations. In the first part of this thesis, the aim was to optimize the performance of LNPs in terms of efficacy and potency. To achieve this, bioinspired and ionizable cationic lipid modifications were explored. Two bioinspired formulations were subsequently developed: phosphatidylserine-LNPs and hybrid LNPs. The first formulation incorporates phosphatidylserine, a lipid typically found in viruses, while the second results from the fusion of LNPs with extracellular vesicles, which are a naturally occurring gene delivery system. Impressively, these formulations surpassed the performance of standard LNPs, exhibiting up to 14-fold higher reporter gene expression in vitro and in vivo in zebrafish larvae and mice. Further investigations highlighted the potential of ionizable cationic lipid modifications to boost the performance of LNPs. The improvements of these formulations were primarily linked to enhancements in cellular uptake and intracellular processing, especially endosomal escape. In the second part, aiming to bridge the gap between in vitro and in vivo, an endosomal escape reporter cell line, zebrafish larvae, and intravital imaging were employed to assess the behavior and performance of various nanomedicines. The insights gained from these experiments were invaluable, helping to determine certain in vitro to in vivo prediction aspects. Notably, the in vitro endosomal escape capability of LNPs and their biodistribution and circulation behavior in zebrafish larvae have emerged as important indicators of their in vivo behavior and performance in rodents. In conclusion, modifying the lipid composition of LNPs significantly improves their performance with respect to efficacy and potency. However, persisting challenges related to cell specificity and cellular uptake emphasize the potential of active targeting strategies, as indicated by preliminary studies. Ultimately, the combination of lipid composition modifications, active targeting strategies, and both in vitro and in vivo models, will serve as a firm foundation for the design of efficacious and potent LNP-based gene therapies

Momentum resolved tunneling in one-dimensional systems

This thesis presents measurements on one dimensional systems in GaAs cleaved edge overgrowth (CEO) samples. Due to their unprecedented quality, the quantum wires in these systems posses long mean free path of more than 10 μm and large subband spacings exceeding 10 meV, which allow for the observation of many effects characteristic to electronic transport in one dimension. We investigate the finite size effects in tunneling between parallel quantum wires with a density inhomogenuity induced by a top gate. This study dif- fers from previous experiments in the inclusion of the gate voltage dependence of conductance. By using both, experiments and numerical simulations, we link the arising patterns in the tunnel conductance to the internal potential landscape inside the quantum wire, enabling the characterization of various sections of varying density. The finiteness of the wire implies that quantized energy levels should exist. A combination of low temperature, good thermal- ization and small DC-voltage bias and AC-excitations allows us to observe Coulomb blockade in these long quantum wires, and extract the single particle level spacing directly from the even/odd spacing of those Coulomb peaks. We also investigate the dispersion of quantum Hall edge states and extract their velocities using two independent methods, momentum resolved tunnel- ing as a function of bias voltage (energy) and also as a function of gate voltage (density), which agree well with each other. These measurements are per- formed in the same CEO device and allow us to leverage our knowledge of the quantum wire system, which is used as a spectrometer in these experiments. We find excellent agreement between the extracted velocities and the predic- tions for hard wall confined edge states. The last two chapters cover phenomena of interacting electrons in one dimen- sion. We observe further evidence for a spin selective Peierls transition by measuring the increase of conductance on the non-universally quantized con- ductance plateau as temperature is increased. We also perform a systematic study of the zero bias anomaly in gate defined quantum wire arrays, spanning a large temperature range of multiple decades, and various densities, ranging from one to three subbands

Oberflächen des Neoliberalismus: Technik, Ästhetik und Kritik bei Jia Zhangke, im Dritten Kino und im postkinematografischen Film

In der vorliegenden Dissertation wird die Digitalisierung von Film und Kino zum Ausgangspunkt einer Auseinandersetzung mit dem Verhältnis von technologischen Veränderungen, ästhetischen Formen und politischer Programmatik in verschiedenen historisch und geografisch divergierenden Filmkorpora gemacht: den Filmen des zeitgenössischen chinesischen Regisseurs Jia Zhangke, den Filmen des Dritten Kinos Lateinamerikas sowie dem sogenannten postkinematografischen Film. In allen Untersuchungen zeigen sich dabei Verbindungen zwischen medialen und wirtschaftlichen Verhältnissen. Eine kritische Medienästhetik muss folglich beides im Blick behalten und die Relevanz technologischer und gesellschaftlicher Bedingtheit im Einzelfall prüfen. Der Verweis auf die Unhintergehbarkeit technologischer Bedingungen wird nicht als Gegenvorschlag zu einer sozio-ökonomischen Perspektive aufgefasst, sondern als Anlass für eine weitere Radikalisierung der Kritik