Institut für Biologie

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  • Publication
    Conformational dynamics of proteins in bacterial pathogens and the innate immune response
    (2024) Hau, Jann-Louis; Fritz, Günter
    Global health is facing two major threads, the rapid rise of multi-drug resistant bacterial pathogens and the increase autoimmune diseases. Therefore, studying the components of host-pathogen interactions is crucially important for the development of novel drugs and diagnostic tools to fight these threats. Both, virulence factors of pathogenic bacteria and the components of the host’s innate immune response are build up by multimeric protein complexes. In order to understand how these systems respond to different conditions and environments and to uncover the underlying molecular mechanisms, the conformational dynamics of these proteins must be resolved. This study focuses on the two important examples of a host-defence protein, S100A8/A9, and a bacterial virulence factor, the Na+-translocating NADH:ubiquinone oxidoreductase (NQR). The heterodimeric protein complex S100A8/A9 is secreted in very high amounts by immune cells at sites of infection and tissue damage. S100A8/A9 is a key element of the innate immune system. It strongly activates inflammatory response and exhibits antimicrobial properties by binding of essential transition metal nutrients. Therefore it is defined as a danger-associated molecular pattern (DAMP). Its role as a DAMP during inflammation and absence in healthy tissue defines S100A8/A9 is used as an excellent biomarker for a variety of inflammatory diseases in human and veterinary medicine. Only the human S100A8/A9 is thoroughly characterised so far. Imaging of S100A8/A9 by a tracer molecule would allow for sensitive and accurate imaging of pathogenic or sterile inflammation. Here, a new protocol for fast and and efficient isolation of human and porcine S100A8/A9 is established, which is also applicable to S100A8/A9 of other species. The characterisation of porcine S100A8/A9 revealed similar properties with respect to structure and metal binding to human S100A8/A9, while the antimicrobial properties of the porcine protein are less pronounced than in the human orthologue. The structures of human S100A9 in complex with different tracer molecules were determined by X-ray crystallography, revealing that the molecular benzimidazole core of the tracer binds into a dynamically adapting pocket of S100A9. Applying a newly established tryptophan fluorescence-based assay, it was shown that the affinity of the tracer is not affected by different imaging tags attached to the benzimidazole core. Since the bezimidazole core exhibits non-favourable pharmacokinetic properties, novel lead compounds for the targeting of S100A8/A9 in inflammation have to be established. New lead structures, which could serve as novel molecular cores, were identified by fragment-based crystallographic screening. As exemplified by the benzimidazole imaging tracers, S100A8/A9 ligands have to fulfil the requirements of the dynamic binding pocket. The identified molecules represent an excellent starting point for the development of a novel class of imaging probes for the sensitive detection of inflammation. The NQR is part of the respiratory chain of the human pathogen Vibrio cholerae. It couples the oxidation of NADH and the reduction of ubiquinone to the translocation of Na+ from the cytoplasm to the periplasm. The resulting Na+ electrochemical gradient, the sodium motive force, is vital for V. cholerae and drives several processes critical for pathogenesis, like e.g. movement of the flagellum and efflux of antibiotics. NQR-activity is linked to the expression of pathogenic factors including the cholera toxin and is therefore classified as a virulence factor itself. Since the NQR has no homologs in humans and is widespread among Gram-negative pathogenic bacteria, it is a promising target for the development of novel classes of antibiotics. However, the mechanism of electron transfer and the coupled sodium translocation as well as the quinone binding site had been elusive. Based on first structural information on the NQR, which exhibited unusual large distances between redox cofactors, drastic conformational changes had been proposed (Steuber et al., 2014). In this study, the structure of the NQR with substrates or inhibitors bound was determined by single particle cryo electron microscopy. The structures reveal that the coupling of electron transfer to conformational changes in the NQR subunits NqrC and NqrF are governed by the redox state of the intramembrane [2Fe-2S] cluster between NqrD/E, defining the NQR as a conformationally coupled redox pump. Furthermore, the binding site of ubiquinone and the NQR inhibitor HQNO was located in NqrB. Sodium ions were identified bound in NqrB, which could represent exit sites of the sodium translocation path. These findings were confirmed for the NQR of Prevotella byrantii by homology modelling. Taken together, the molecular mechanism described for the V. cholerae NQR applies also to NQRs from other organisms and homologous complexes. The described NQR mechanism and substrate binding sites lay the foundation for the structure-based design of NQR-inhibitors which could serve as new antibacterial drugs. In summary, the findings presented in this study promote the development of novel diagnostic tools and new antibiotics to combat the emerging threats of autoimmune diseases and multidrug resistant bacterial pathogens.
  • Publication
    Integrative description of Temnothorax siculus sp. n.: a new ant species from Sicily, Italy (Hymenoptera, Formicidae)
    (2025) Schifani, Enrico; Alicata, Antonio; Prebus, Matthew M.; Csősz, Sándor; Schifani, Enrico; Department of Chemistry, Environmental Sustainability, and Life Sciences, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy; Alicata, Antonio; Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy;; Prebus, Matthew M.; Social Insect Research Group, School of Life Sciences, Arizona State University, 550 E Orange St., Tempe, AZ 85281, USA;; Csősz, Sándor; HUN-REN-ELTE-MTM Integrative Ecology Research Group, Pázmány Péter ave 1/C, 1117 Budapest, Hungary; Fernández, Fernando; Guerrero, Roberto José
    The mostly Holarctic genus Temnothorax (Hymenoptera, Formicidae) is the most diverse ant genus in temperate regions. The Mediterranean, a biodiversity hotspot of rare ant species, hosts over 150 Temnothorax taxa, including several short-range endemics. Over the last few years, phylogenomic reconstructions and integrative taxonomy have significantly improved the understanding of global Temnothorax diversity, but much taxonomic work is still needed in the Mediterranean region. Here, we present the integrative description of a new species of the genus, discovered in the central Mediterranean island of Sicily: Temnothorax siculus sp. n. is defined and compared to congeneric species integrating morphometrics and phylogenomics. It is a ground-nesting, lowland species, of which workers were regularly observed foraging on bushes and small trees. In the global phylogeny, covering all the main lineages of the region, it belongs to the Palearctic clade and is related to the tuberum and unifasciatus complexes. Morphological separation from other Sicilian Temnothorax species can generally be achieved on qualitative characters, but we also provide morphometric discriminant functions to separate it from T. apenninicus and especially T. unifasciatus . Temnothorax siculus has been rarely collected but appears to be widespread in Sicily, and may occur in neighboring regions.
  • Publication
    Morphological and molecular identification of sarcocystis arctica in captive cheetahs (Acinonyx jubatus) in China helps clarify phylogenetic relationships with Sarcocystis caninum and Sarcocystis felis
    (2025) Liao, Zhe; Zhu, Niuping; Yang, Yurong; Deng, Shuangsheng; Jäkel, Thomas; Hu, Junjie; Liao, Zhe; Yunnan Key Laboratory for Plateau Mountain Ecology, Restoration of Degraded Environments, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China;; Zhu, Niuping; College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (N.Z.); (Y.Y.); Yang, Yurong; College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (N.Z.); (Y.Y.); Deng, Shuangsheng; Joint Laboratory of Virology & Immunity, School of Biological Sciences, Yunnan University, Kunming 650091, China;; Jäkel, Thomas; Institute of Biology, Department of Parasitology, University of Hohenheim, 70599 Stuttgart, Germany; Hu, Junjie; Yunnan Key Laboratory for Plateau Mountain Ecology, Restoration of Degraded Environments, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China;; Salvarani, Felipe M.; Domingues, Sheyla Farhayldes Souza; Da Silveira, Júlia Angélica Gonçalves
    To date, only one case is known where protozoan parasites of the genus Sarcocystis were found to infect cheetahs ( Acinonyx jubatus ); the cysts in the musculature were morphologically identified as S. felis . Here, we characterized sarcocysts by morphological and molecular methods that were observed in cheetahs who died in zoos in China. Only one type of sarcocyst was present in two of six cheetahs. By light microscopy, the sarcocyst wall was striated, 1.4–2.1 μm thick. Ultrastructurally, the wall had irregular-shaped, small villar protrusions, resembling wall type 9c, similar to those of S. arctica , S. caninum , and S. felis . The samples shared their highest molecular identity values with those of S. arctica and S. caninum : 99.9–100% and 99.8–100% (18S rRNA), 99.5% and 99.3–99.5% (28S rRNA), 95.9–97.5% and 96.3–97.3% (ITS-1), and 99.6% and 99.2–99.7% ( cox 1), respectively. Compared with ITS-1 of S. felis , identities ranged between 87.5% and 88.9%. Phylogenetic reconstruction revealed that the newly sequenced Sarcocystis clustered with S. arctica and S. caninum , whereas S. felis (ITS-1) and S. canis (ITS-1, 18S rRNA, cox 1) were sister species. Thus, we addressed the Sarcocystis species from the cheetahs as S. arctica , which is the first record of a Sarcocystis species believed to be specific for canids as intermediate hosts to infect a feline host.
  • Publication
    Exploring ND-011992, a quinazoline-type inhibitor targeting quinone reductases and quinol oxidases
    (2023) Kägi, Jan; Sloan, Willough; Schimpf, Johannes; Nasiri, Hamid R.; Lashley, Dana; Friedrich, Thorsten; Kägi, Jan; Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany; Sloan, Willough; Department of Chemistry, William & Mary, Williamsburg, USA; Schimpf, Johannes; Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany; Nasiri, Hamid R.; Department of Cellular Microbiology, University Hohenheim, Stuttgart, Germany; Lashley, Dana; Department of Chemistry, William & Mary, Williamsburg, USA; Friedrich, Thorsten; Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
    Bacterial energy metabolism has become a promising target for next-generation tuberculosis chemotherapy. One strategy to hamper ATP production is to inhibit the respiratory oxidases. The respiratory chain of Mycobacterium tuberculosis comprises a cytochrome bcc:aa3 and a cytochrome bd ubiquinol oxidase that require a combined approach to block their activity. A quinazoline-type compound called ND-011992 has previously been reported to ineffectively inhibit bd oxidases, but to act bactericidal in combination with inhibitors of cytochrome bcc:aa3 oxidase. Due to the structural similarity of ND-011992 to quinazoline-type inhibitors of respiratory complex I, we suspected that this compound is also capable of blocking other respiratory chain complexes. Here, we synthesized ND-011992 and a bromine derivative to study their effect on the respiratory chain complexes of Escherichia coli. And indeed, ND-011992 was found to inhibit respiratory complex I and bo3 oxidase in addition to bd-I and bd-II oxidases. The IC50 values are all in the low micromolar range, with inhibition of complex I providing the lowest value with an IC50 of 0.12 µM. Thus, ND-011992 acts on both, quinone reductases and quinol oxidases and could be very well suited to regulate the activity of the entire respiratory chain.
  • Publication
    Disc mower versus bar mower: Evaluation of the direct effects of two common mowing techniques on the grassland arthropod fauna
    (2025) von Berg, Lea; Frank, Jonas; Betz, Oliver; Steidle, Johannes L. M.; Böttinger, Stefan; Sann, Manuela; von Berg, Lea; Evolutionary Biology of Invertebrates, Institute for Evolution and Ecology, University of Tübingen, Tübingen, Germany; Frank, Jonas; Fundamentals of Agricultural Engineering, Institute for Agricultural Engineering, University of Hohenheim, Stuttgart, Germany; Betz, Oliver; Evolutionary Biology of Invertebrates, Institute for Evolution and Ecology, University of Tübingen, Tübingen, Germany; Steidle, Johannes L. M.; Chemical Ecology, Institute for Biology, University of Hohenheim, Stuttgart, Germany; Böttinger, Stefan; Fundamentals of Agricultural Engineering, Institute for Agricultural Engineering, University of Hohenheim, Stuttgart, Germany; Sann, Manuela; Chemical Ecology, Institute for Biology, University of Hohenheim, Stuttgart, Germany
    1. In Central Europe, species‐rich grasslands are threatened by intensive agriculture with frequent mowing, contributing to the reduction of arthropods such as insects and spiders. However, comprehensive and standardised studies on the direct effects of the two most agriculturally relevant mowing techniques, e.g., double‐blade bar mower versus disc mower, are lacking. 2. In a 2‐year experiment, we have investigated the direct effect of mowing on eight abundant arthropod groups in grassland, covering two seasonal mowing events in both years, using a randomised block design. We compared (a) an unmown control, (b) a double‐blade bar mower and (c) a disc mower. 3. For most of the taxonomic groups studied, a significantly lower number of individuals was found in the experimental plots immediately after mowing, regardless of the mowing technique, compared to an unmown control. This was not the case for Orthoptera and Coleoptera, which did not show a significant reduction in the number of individuals for both mowing techniques (Orthoptera) or only for the double‐blade bar mower (Coleoptera). 4. Between both mowing techniques, no significant differences were found for all taxonomic groups investigated. 5. Synthesis and applications: Our findings suggest that mowing in general has a negative impact on abundant arthropod groups in grassland, regardless of the method used. Tractor‐driven double‐blade bar mowers do not seem to be a truly insect‐friendly alternative to a conventional disc mower. Other factors such as cutting height and mowing regimes should be seriously considered to protect spiders and insects from the negative effects of mowing. In addition, we strongly recommend the maintenance of unmown refugia. Insects and spiders that are spared by mowing can take refuge in these unmown areas to avoid subsequent harvesting and thermally unfavourable conditions that arise on mown areas. Further, unmown refugia are basic habitat structures for a subsequent recolonisation of mown areas once the flora has recovered.
  • Publication
    Identification of novel genes including NAV2 associated with isolated tall stature
    (2023) Weiss, Birgit; Ott, Tim; Vick, Philipp; Lui, Julian C.; Roeth, Ralph; Vogel, Sebastian; Waldmüller, Stephan; Hoffmann, Sandra; Baron, Jeffrey; Wit, Jan M.; Rappold, Gudrun A.
    Very tall people attract much attention and represent a clinically and genetically heterogenous group of individuals. Identifying the genetic etiology can provide important insights into the molecular mechanisms regulating linear growth. We studied a three-generation pedigree with five isolated (non-syndromic) tall members and one individual with normal stature by whole exome sequencing; the tallest man had a height of 211 cm. Six heterozygous gene variants predicted as damaging were shared among the four genetically related tall individuals and not present in a family member with normal height. To gain insight into the putative role of these candidate genes in bone growth, we assessed the transcriptome of murine growth plate by microarray and RNA Seq. Two (Ift140, Nav2) of the six genes were well-expressed in the growth plate. Nav2 (p-value 1.91E-62) as well as Ift140 (p-value of 2.98E-06) showed significant downregulation of gene expression between the proliferative and hypertrophic zone, suggesting that these genes may be involved in the regulation of chondrocyte proliferation and/or hypertrophic differentiation. IFT140, NAV2 and SCAF11 have also significantly associated with height in GWAS studies. Pathway and network analysis indicated functional connections between IFT140, NAV2 and SCAF11 and previously associated (tall) stature genes. Knockout of the all-trans retinoic acid responsive gene, neuron navigator 2 NAV2, in Xenopus supports its functional role as a growth promotor. Collectively, our data expand the spectrum of genes with a putative role in tall stature phenotypes and, among other genes, highlight NAV2 as an interesting gene to this phenotype.
  • Publication
    Limitations of soil-applied non-microbial and microbial biostimulants in enhancing soil P turnover and recycled P fertilizer utilization - a study with and without plants
    (2024) Herrmann, Michelle Natalie; Griffin, Lydia Grace; John, Rebecca; Mosquera-Rodríguez, Sergio F.; Nkebiwe, Peteh Mehdi; Chen, Xinping; Yang, Huaiyu; Müller, Torsten; Herrmann, Michelle Natalie; Institute of Crop Science, Department of Fertilization and Soil Matter Dynamics, University of Hohenheim, Stuttgart, Germany; Griffin, Lydia Grace; Institute of Crop Science, Department of Fertilization and Soil Matter Dynamics, University of Hohenheim, Stuttgart, Germany; John, Rebecca; Institute of Crop Science, Department of Fertilization and Soil Matter Dynamics, University of Hohenheim, Stuttgart, Germany; Mosquera-Rodríguez, Sergio F.; Institute of Crop Science, Department of Fertilization and Soil Matter Dynamics, University of Hohenheim, Stuttgart, Germany; Nkebiwe, Peteh Mehdi; Institute of Crop Science, Department of Fertilization and Soil Matter Dynamics, University of Hohenheim, Stuttgart, Germany; Chen, Xinping; College of Resources and Environment, Academy of Agricultural Sciences, Southwest University, Chongqing, China; Yang, Huaiyu; College of Resources and Environment, Academy of Agricultural Sciences, Southwest University, Chongqing, China; Müller, Torsten; Institute of Crop Science, Department of Fertilization and Soil Matter Dynamics, University of Hohenheim, Stuttgart, Germany
    Introduction: Phosphorus recovery from waste streams is a global concern due to open nutrient cycles. However, the reliability and efficiency of recycled P fertilizers are often low. Biostimulants (BS), as a potential enhancer of P availability in soil, could help to overcome current barriers using recycled P fertilizers. For this, a deeper understanding of the influence of BSs on soil P turnover and the interaction of BSs with plants is needed. Methods: We conducted an incubation and a pot trial with maize in which we testednon-microbial (humic acids and plant extracts) and microbial BSs (microbial consortia) in combination with two recycled fertilizers for their impact on soil P turnover, plant available P, and plant growth. Results and discussion: BSs could not stimulate P turnover processes (phosphatase activity, microbial biomass P) and had a minor impact on calcium acetate-lactate extractable P (CAL-P) in the incubation trial. Even though stimulation of microbial P turnover by the microbial consortium and humic acids in combination with the sewage sludge ash could be identified in the plant trial with maize, this was not reflected in the plant performance and soil P turnover processes. Concerning the recycled P fertilizers, the CAL-P content in soil was not a reliable predictor of plant performance with both products resulting in competitive plant growth and P uptake. While this study questions the reliability of BSs, it also highlights the necessity toimprove our understanding and distinguish the mechanisms of P mobilization in soil and the stimulation of plant P acquisition to optimize future usage.
  • Publication
    Association between vitamin D status and eryptosis - results from the German National Cohort Study
    (2023) Ewendt, Franz; Schmitt, Marvin; Kluttig, Alexander; Kühn, Julia; Hirche, Frank; Kraus, Frank B.; Ludwig-Kraus, Beatrice; Mikolajczyk, Rafael; Wätjen, Wim; Bürkner, Paul-Christian; Föller, Michael; Stangl, Gabriele I.; Ewendt, Franz; Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany; Schmitt, Marvin; Cluster of Excellence SimTech, University of Stuttgart, Stuttgart, Germany; Kluttig, Alexander; Institute of Medical Epidemiology, Biostatistics, and Informatics, Medical Faculty of the Martin Luther University Halle-Wittenberg, Halle (Saale), Germany; Kühn, Julia; Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany; Hirche, Frank; Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany; Kraus, Frank B.; Central Laboratory, Department of Laboratory Medicine, University Hospital Halle, Halle (Saale), Germany; Ludwig-Kraus, Beatrice; Central Laboratory, Department of Laboratory Medicine, University Hospital Halle, Halle (Saale), Germany; Mikolajczyk, Rafael; Institute of Medical Epidemiology, Biostatistics, and Informatics, Medical Faculty of the Martin Luther University Halle-Wittenberg, Halle (Saale), Germany; Wätjen, Wim; Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany; Bürkner, Paul-Christian; Cluster of Excellence SimTech, University of Stuttgart, Stuttgart, Germany; Föller, Michael; Department of Physiology, University of Hohenheim, Stuttgart, Germany; Stangl, Gabriele I.; Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
    Vitamin D, besides its classical effect on mineral homeostasis and bone remodeling, can also modulate apoptosis. A special form of apoptosis termed eryptosis appears in erythrocytes. Eryptosis is characterized by cell shrinkage, membrane blebbing, and cell membrane phospholipid disorganization and associated with diseases such as sepsis, malaria or iron deficiency, and impaired microcirculation. To our knowledge, this is the first study that linked vitamin D with eryptosis in humans. This exploratory cross-sectional trial investigated the association between the vitamin D status assessed by the concentration of plasma 25-hydroxyvitamin D (25(OH)D) and eryptosis. Plasma 25(OH)D was analyzed by LC–MS/MS, and eryptosis was estimated from annexin V-FITC-binding erythrocytes by FACS analysis in 2074 blood samples from participants of the German National Cohort Study. We observed a weak but clear correlation between low vitamin D status and increased eryptosis ( r  =  − 0.15; 95% CI [− 0.19, − 0.10]). There were no differences in plasma concentrations of 25(OH)D and eryptosis between male and female subjects. This finding raises questions of the importance of vitamin D status for eryptosis in terms of increased risk for anemia or cardiovascular events.
  • Publication
    Kinetics and dynamics of plant toxins in sequestering insects
    (2024) Betz, Anja; Petschenka, Georg
    Many plants produce a variety of chemical compounds to protect themselves from herbivorous insects. However, numerous insects have developed adaptations to tolerate and even utilize these toxins. These adaptations can include behavioral changes (feeding on or avoiding toxic plant parts), detoxification (metabolizing or excreting the toxins), barriers (preventing uptake or protecting target sites), or sequestration (storing secondary plant compounds in the body for self-defense). A widely distributed group of phytochemicals are the cardiac glycosides, which have been extensively studied in chemical ecology. These toxic steroids act in a highly specific manner by inhibiting the Na+/K+-ATPase, an essential transmembrane cation carrier that is ubiquitously expressed in animal cells. A cardiac glycoside-resistant Na+/K+-ATPase was first described in the monarch butterfly (Danaus plexippus, Lepidoptera: Danaini), which sequesters cardiac glycosides from its food plants. This led to the hypothesis that the evolution of a resistant Na+/K+-ATPase is linked to the sequestration of cardiac glycosides. It is now known that species from at least six insect orders possess Na+/K+-ATPases with reduced affinity for cardiac glycosides. This resistance is mediated by a few amino acid substitutions in the binding site, a mechanism referred to as "target site insensitivity." Interestingly, the ability to tolerate dietary cardiac glycosides does not necessarily require a resistant Na+/K+-ATPase. For example, the non-sequestering common crow (Euploea core, Lepidoptera: Danaini) can develop on cardiac glycoside-containing plants without expressing a resistant Na+/K+-ATPase. Although plant toxin sequestration has been documented in more than 275 insect species, the underlying kinetics and dynamics of toxin transport - such as the duration and mode of transport, target sites, barriers, and potential modified binding sites - remain largely unknown. Like the Danaini, milkweed bugs (Heteroptera: Lygaeinae) also have the ability to sequester cardiac glycosides. Remarkably, one species within this family, Spilostethus saxatilis, is able to sequester not only cardiac glycosides but also colchicine alkaloids from autumn crocus (Colchicum autumnale, Liliales: Colchicaceae). Colchicine binds to unpolymerized betatubulin at the interface with alpha-tubulin, thereby inhibiting microtubule formation. However, it is not known how colchicine resistance is achieved in S. saxatilis and whether there is also target site insensitivity. In my dissertation, I investigated the mechanisms behind the sequestration of cardiac glycosides in D. plexippus and colchicine in S. saxatilis within a phylogenetic framework. In D. plexippus, I was able to show that sequestration begins at the behavioral level, because unlike related species, caterpillars can increase their toxicity in the adult stage by drinking plant latex containing cardiac glycosides. I also found that a large portion of cardiac glycosides is lost during metamorphosis, suggesting that excessive toxin intake during the larval stage may be important. Furthermore, I could show that the uptake of the toxin by the intestinal epithelium is a very rapid process although probably not specific to D. plexippus, as uptake in nonsequestering lepidopterans does also occur. Regarding the sequestration of colchicine in S. saxatilis, I identified an amino acid substitution in the colchicine binding site of tubulin. Subsequently, an in vitro colchicine binding assays with crude tubulin extract of bug tissue and an in vivo feeding experiment with genetically modified Drosophila with one matching substitution in the colchicine binding site were conducted. Together both experiments suggest that this modification may play a crucial role in the sequestration of colchicine, indicating a novel natural target site resistance. My dissertation provides new insights into how insects adapt to toxic food plants and how they sequester their toxic metabolites. This contributes not only to a better understanding of how insects cope with natural plant toxins, but also to a better understanding of the physiological complexity of these adaptations.
  • Publication
    Radial stem growth response of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to severe drought depending on soil properties and rooting characteristics
    (2024) Spangenberg, Göran; Hein, Sebastian
    The increase in severe droughts and heat waves caused by climate change has impacted forests worldwide. One of these effects is the increase in drought-related damage to trees and tree dieback in many regions of the world. This became visible in Central Europe during and after the extreme drought of 2018. Not only severely damaged forests but many still existing forests must also be adapted to the changing climate. In this forest conversion, the adaptation of tree species composition to the changing climatic conditions, e.g., by planting other tree species, is an important measure. Drought tolerance is among the most important criteria for tree species selection. In this context, the planting of non-native tree species that are considered drought tolerant is an increasingly used silvicultural strategy. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), which is native to North America, is an important substitute tree species with a higher drought tolerance, especially compared to Norway spruce (Picea abies (L.) Karst.), which has experienced severe drought damage in different regions of Europe. However, there has also been an increase in drought-related problems with Douglas-fir in some regions of Europe and North America. There is a need for research on the influence of site and rooting characteristics on the drought tolerance of this tree species. The objective of this dissertation was to investigate the influence of two soil properties (soil texture and plant-available water capacity) and two rooting characteristics (effective rooting depth and fine root density at a 0–40 cm soil depth) on the drought tolerance of Douglas-fir during the extreme drought year 2018. Different indicators derived from measurements of radial stem growth and stem radius changes were used to assess drought tolerance. Seven study sites were selected along a soil texture gradient from sand to clay. To investigate the influence of soil and rooting characteristics, other influencing factors on the drought tolerance of Douglas-fir were kept as consistent as possible. For this purpose, the study sites were selected in close proximity in southern Germany, at an elevation of approximately 500m a.s.l. Since the variety and provenance of Douglas-fir also influence drought tolerance, genetic origin analysis was carried out. As a result, all trees examined were clearly assigned to the coastal variety. They originated from the central area of the natural distribution range of the coastal variety. The soil physical and rooting characteristics were determined on a representative soil profile for each of the seven sites. In the investigations in Chapter II, cores were collected from Douglas-fir trees with an increment borer and tree ring widths were measured. The growth response indices of resistance, recovery, and resilience were derived from this as indicators of drought tolerance. These indices quantify the ability of trees to maintain stem growth during drought stress events and stem growth recovery after drought. In the study in Chapter III, stem radius changes were measured using dendrometers with high temporal and spatial resolution at the same study sites. Based on these data, the water status parameters maximum daily shrinkage and tree water deficit were derived for two pronounced drought periods in the extreme drought year 2018. In addition, growth onset and cessation for 2018 were estimated from dendrometer measurements and compared with the corresponding values for years with more precipitation, 2017 and 2019. Linear mixed-effects models were used to analyze the influence of soil and rooting characteristics on the indicators of drought tolerance and water status in Douglas-fir. The following overall conclusions can be drawn from the results of both studies. In general, Douglas-fir showed a higher drought tolerance on silty and sandy soils. On clay-dominated soils, a higher risk of drought stress is to be expected during very severe drought. A higher plant-available water capacity only reduced drought stress in Douglas-fir at the initial stage of the extreme drought in 2018. In the advanced stage of drought, this positive effect was no longer observed. A greater rooting depth reduced drought stress in the later stage of extreme drought and proved to be an influencing factor that improved drought tolerance in the analysis of the interannual radial growth. Douglas-fir trees only benefited from more intensive rooting in the top 40 cm of soil in the initial stage of extreme drought. In the later drought stage, no significant influence was detected. Based on measurement of the interannual radial stem growth and intra-annual stem radius changes, this drought stress study provides recommendations for Douglas-fir cultivation under the predicted climatic changes with an increased occurrence of severe drought periods. The combined application of the two measurement methods reduced method-specific uncertainties and answered additional research questions. There are comparatively few studies on the drought tolerance of trees that examine the relationships between soil properties, rooting characteristics, and aboveground tree responses to drought. This investigation shows the importance of such studies in understanding the response patterns of trees to very severe drought events.
  • Publication
    Effects of feeding diets without mineral P supplement on intestinal phytate degradation, blood concentrations of Ca and P, and excretion of Ca and P in two laying hen strains before and after onset of laying activity
    (2024) Sommerfeld, Vera; Bennewitz, Jörn; Camarinha-Silva, Amélia; Feger, Martina; Föller, Michael; Huber, Korinna; Oster, Michael; Ponsuksili, Siriluck; Schmucker, Sonja; Seifert, Jana; Stefanski, Volker; Wimmers, Klaus; Rodehutscord, Markus
    The objective of this study was to characterize intestinal phytate degradation and mineral utilization by 2 laying hen strains before and after the onset of egg laying using diets without or with a mineral phosphorus (P) supplement. One offspring of 10 roosters per strain (Lohmann Brown-classic [LB] and Lohmann LSL-classic [LSL]) was sacrificed before (wk 19) and after (wk 24) the onset of egg-laying activity and following 4 wk placement in a metabolic unit. Diets were corn-soybean meal-based and without supplemented P (P-) or with 1 g/kg supplemented P (P+) from monocalcium phosphate. In wk 19 and 24, the blood plasma and digesta of duodenum+jejunum and distal ileum were collected. The concentration of P in blood plasma was higher in hens fed P+ than P- (P < 0.001). In duodenum + jejunum and ileum content, the concentrations of InsP6, Ins(1,2,4,5,6)P5 and Ins(1,2,3,4,5)P5 were lower in P- than in P+ (P ≤ 0.009). In duodenum+jejunum, the concentrations of InsP6, Ins(1,2,4,5,6)P5 and Ins(1,2,3,4,5)P5 were lower in wk 24 than 19 and lower in LSL than LB hens (P < 0.001). The concentration of myo-inositol (MI) in duodenum + jejunum content was lower in wk 19 than 24 (P < 0.001). Following a 4-d total excreta collection, the retained amount of P was higher in P+ than P- (P < 0.001). Phosphorus retention was lower in LB hens fed P- than in other treatments (P × strain: P = 0.039). In the jejunal tissue, some genes related to intracellular InsP metabolism were higher expressed in LB than LSL hens. The renunciation of mineral P increased endogenous phytate degradation, but more P was retained with supplemented P. Differences in endogenous phytate degradation between the periods before and after the onset of egg laying might be attributed to different Ca concentrations in intestinal digesta caused by different Ca needs in both periods.
  • Publication
    Effects of myo-inositol supplementation in the diet on myo-inositol concentrations in the intestine, blood, eggs, and excreta of laying hens
    (2025) Sommerfeld, Vera; Hanauska, Anna; Huber, Korinna; Bennewitz, Jörn; Camarinha-Silva, Amélia; Feger, Martina; Föller, Michael; Oster, Michael; Ponsuksili, Siriluck; Schmucker, Sonja; Seifert, Jana; Stefanski, Volker; Wimmers, Klaus; Rodehutscord, Markus
    The objectives of this study were to investigate whether an increased dietary myo-inositol (MI) supply translates into changes in MI concentrations and endogenous mucosal phosphatase activities in the intestine of laying hens and whether different laying hen strains respond differently to MI supplementation. The diets were corn–soybean meal-based and supplemented without (MI0) or with 1 (MI1), 2 (MI2), or 3 (MI3) g MI/kg feed. Ten hens per strain (Lohmann Brown-classic (LB) and Lohmann LSL-classic (LSL)) and diet were sacrificed at the age of 30 wk following a 4-wk stay in a metabolic unit. The blood plasma, digesta of the duodenum+jejunum and distal ileum, mucosa of the duodenum, and eggs were collected at wk 30. The concentration of MI in the blood plasma was increased by MI supplementation (P < 0.001); however, that of MI3 did not further increase compared with MI2. The concentration of MI in the duodenum+jejunum and ileum increased steadily (P < 0.001). The MI concentration in the duodenum+jejunum was higher in LB than in LSL hens (P = 0.017). The MI concentration in egg yolk was increased by MI supplementation (P < 0.001) and was higher in LB than in LSL hens (P = 0.015). Strain or diet did not affect mucosal phosphatase activity. Myo-inositol flow at the terminal ileum and postileal disappearance increased with each increment in MI supplementation (P < 0.001) and was higher in LB than in LSL hens (P ≤ 0.041). Regression analysis indicated that, on average, 84% of supplemented MI was retained in the body or metabolized and excreted in a different form. Based on the measured MI concentrations in the blood and eggs, dietary MI was not completely absorbed in the small intestine and, to a different extent, in the two laying hen strains. A higher dietary MI supply was followed by higher intestinal absorption or metabolism by microorganisms. The fate of supplemented MI and its relevance to birds warrant further research.
  • Publication
    Ontogeny and reproductive paleobiology in the Mesozoic marine reptile clade Ichthyosauria
    (2023) Miedema, Feiko; Schoch, Rainer
    Ichthyosaurs were viviparous marine reptiles that occupied many consumer niches in the marine ecosystems of the Mesozoic. Their viviparous reproductive strategy lends us the opportunity to study their prenatal development in great detail and lets us assess their birthing strategies. Moreover, some species are common in Lagerstätten deposits, which means we are likewise able to assess postnatal ontogeny. The assessment of ontogeny is important in our understanding of an extinct animal’s paleobiology and necessary for its’ correct phylogenetic placement. After studying the prenatal osteological development in the ichthyosaur Stenopterygius we now recognize 4 different stages on the basis of relative cranial ossification. The overall ossification sequence was very similar to other diapsids. The establishment of multiple prenatal stages was a first for an extinct sauropsid. We likewise erected 3 postnatal stages in Stenopterygius on the basis of cranial ossification, fusion and element morphology. Recognizing multiple postnatal ontogenetic stages in model (fossil) organism such as Stenopterygius will help recognize the ontogenetic stages of less well-known species and single specimens as well as refine phylogenetic characters which may be prone to major ontogenetic differences. Moreover, the cranial ossification and ontogeny of Mixosaurus cornalianus was studied. Due to sample size and the difficult crushed material, we were unable to establish the same stages as in Stenopterygius. However, we did clarify certain parts in Mixosaurus osteology, established some ontogenetically variable traits, most notably regarding the braincase and lower jaw, and were able to assess in detail a prenatal stage. Early cranial development in Mixosaurus differs from that of Stenopterygius regarding the precise ossification of the basioccipital and exoccipital, whereby Mixosaurus possibly shows a more ancestral developmental pathway. The notochord is a structure established early in development of vertebrates and recedes during the ossification of the vertebral centra. After studying much fetal material of several taxa of ichthyosaurs across phylogeny we established that the relative size of the notochord pit can function as a proxy for determining prenatal stage (as compared to Stenopterygius). This shows that the developmental pathway is relatively conservative across ichthyosaurs, as expected, and will help in determining prenatal stage in the absence of cranial material in subsequent finds. Lastly the birth preference of ichthyosaurs was re-evaluated. A longstanding idea within the community was that ichthyosaurs preferentially (and almost exclusively) gave birth tail-first as head-first birth would increase the risk of drowning of the fetus during birth. An early diverging ichthyosaur, Chaohusaurus, was found to have head-first birth. The authors argued that it must be the ancestral and terrestrial condition, citing the drowning hypothesis. After studying three pregnant specimens of the ichthyosaur Mixosaurus, we assessed birthing orientation in all ichthyosaurs in which pregnant specimens are known. Moreover, we looked at birthing in aquatic and terrestrial extant and all extinct aquatic amniotes. We see no link between birthing in an aquatic medium and tail-first birth and thereby deem the drowning hypothesis improbable. We propose two new hypotheses for birth orientation preference. Furthermore, based on all known ichthyosaur fetuses we propose that a preference for tail-first birth originated much later in ichthyosaur evolution than previously anticipated.
  • Publication
    Pachycormid fishes from the early jurassic (Toarcian) Posidonienschiefer formation of southern Germany
    (2023) Cooper, Samuel Lewis Alan; Schoch, Rainer
    Pachycormiformes were a successful clade of Mesozoic actinopterygian fishes, with a patchy fossil record spanning the Lower Jurassic to Upper Cretaceous. Current phylogeny resolves pachycormids as a monophyletic grouping of stem-teleosts (Teleosteomorpha) and therefore they hold an important evolutionary position in the debated Neopterygii to Teleostei transition. The Toarcian Posidonienschiefer Formation – a marine Konservat Lagerstätte deposited predominately in Baden-Württemberg (SW Germany) – records the oldest occurrences of Pachycormiformes in the fossil record, along with the first ~3 million years of their evolutionary history. The formation is therefore ideal for testing major evolutionary concepts for this clade; including their origins, early diversity, palaeoecology, early adaptive radiation, and survivorship across the Early Toarcian Oceanic Anoxic Event (ETOAE). Pachycormids are geographically confined the north-western Tethys during the Toarcian, with their fossils found in Liassic black shales and marls of the UK, France, Belgium, Luxembourg, Germany and northern Italy. Of the supposed 17 pachycormid species previously cited as being present in Posidonienschiefer Formation by various authors, I consider only 9 species to be valid; although just 7 of these are actually present in the German Lias: Euthynotus incognitus, Euthynotus intermedius, Sauropsis veruinalis, Pachycormus macropterus, Saurostomus esocinus, Germanostomus pectopteri, and Ohmdenia multidentata. Unfortunately, most of these taxa are poorly described and inadequately diagnosed, thus creating a caveat of problems surrounding their taxonomic identities. Many specimens are commonly misidentified, both in museum collections and published datasets, which is a major hindrance preventing reliable anatomical and evolutionary studies on Pachycormiformes. The primary objective of this thesis is to resolve the taxonomic identifies of certain Toarcian pachycormids in the Posidonienschiefer Formation, and provide a constrain on their stratigraphic and palaeobiogeographic ranges (Chapters 2, 3, Appendix 1). Only after this is resolved can the bigger questions surrounding pachycormid evolution and diversity through time be more accurately addressed. Provided in Chapter 1 is a detailed overview of the known stratigraphic and palaeobiogeographic ranges of named pachycormid taxa across their fossil record. Herein, I highlight notable gaps in their occurrences, changes in species richness through time, and discuss the abiotic and human factors biasing the pachycormid fossil record. Peaks in taxic diversity appear to correlate with eustatic sea level rise, whilst low stand periods and an associated depletion of suitable fossiliferous deposits are responsible for gaps. In Chapter 2, I review and redescribe the problematic historic species Saurostomus esocinus, providing a revised diagnosis, phylogeny, distribution ranges, and new definitive criteria to differentiate this taxon from the commonly conflated genus, Pachycormus. S. esocinus is shown to be an early diverging member of the suspension-feeding lineage of pachycormids due the detection of important shared characters (e.g., loss of infraorbital and suborbital bones; reduced skeleton ossification). I also describe a new large pachycormid from the Posidonienschiefer Formation and discuss its evolutionary significance to the evolution of suspension-feeding capabilities in Pachycormiformes. Germanostomus pectopteri is differentiated from Saurostomus esocinus by proportionately more elongate jaws, an enlarged premaxilla, loss of the opercular process on the hyomandibula, and large inverted ‘D’-shaped pectoral fins which are suitable for upwards lift. Morphologies and trends in the pachycormiform gastrointestinal tract are also discussed in an evolutionary context. Classification of Pachycormiformes is revised with the monospecific Family Pachycormidae now divided into two Subfamilies: Asthenocorminae and Hypsocorminae. Additionally, I review the ecology of Pachycormus macropterus – the most abundant and wide spread pachycormid species in the Early Jurassic. A dietary shift in prey preference associated with ontogeny is identified in P. macropterus, with juveniles obligate piscivores and adults facultatively teuthophagous. One P. macropterus specimen preserves a large ammonite shell inside of the gut, demonstrating a previously unknown trophic relationship between pachycormids and ammonoids. Evidence for cannibalism in pachycormids, based on conspecific gut contents in Pachycormus, is presented for the first time. Body size distribution in Pachycormus specimens between different sites (Curcy, France, and Holzmaden, Germany) suggest that juveniles occupied mostly coastal environments but migrated further off-shore later in ontogeny, possibly to exploit the high abundance of pelagic coleoids in these areas. Comparisons in gut contents suggest that interspecific competition between large asthenocormine pachycormids was likely low in the Posidonienschiefer Formation with Pachycormus favouring non-belemnoid teuthids (e.g. Teudopsis sp.), Saurostomus and Germanostomus consuming mainly non-belemnite belemnoids (e.g. Clarkeiteuthis conocauda) and small fishes, whilst only Ohmdenia multidentata ate belemnites. Changes in species abundance and taxic diversity of pachycormids in the Posidonienschiefer Formation is likely associated with changing water depth. Pachycormids have a low detection rate in the lower beds (tenuicostatum Zone), but become extremely abundant following the fallout of the ETOAE in the serpentinum Zone, only to drastically decline in the upper part of the section (bifrons Zone). External to Pachycormiformes, a new genus and species of coccolepidid fish (Coccolepididae) is described from the Posidonienschiefer Formation at Holzmaden (Chapter 6); the first to be named from the Toarcian, including one specimen preserved as a regurgitalite (Speiballen).
  • Publication
    From glands to ground plans: Evolutionary morphology in Hymenoptera through space and time
    (2023) Ulmer, Jonah Michael; Krogmann, Lars
    Hymenoptera is one of the most species-rich and diverse groups of life, with over 153000 extant species described and another 2000 extinct. The evolutionary history of the group spans from the Triassic, around 250 million years ago, to the present day. In that time the order has spread and adapted to nearly every corner of the earth and nearly every conceivable ecological niche. That adaptation and time has led to innumerable forms and morphologies which have come and gone. Understanding the underlying patterns and impacts of these forms is perhaps the most fundamental and significant endeavor within systematics. In the first chapter, the earliest lineage of the megadiverse Chalcidoidea, Protoididae, is described from fourteen pieces of amber from the Lower Cretaceous, approximately 130 million years ago. Two genera and ten new species are described along with a key to the new family. This newly discovered stem-group chalcid provides unique insights into the early ground-plan of the superfamily which is investigated relative to other fossil and early crown-group lineages. From a thorough morphological investigation of the group, we evaluate the earliest forms of known plesiomorphies and hypothesize the transitionary forms of stem-group to crown-group chalcids. Due to its age, Protoitidae also allows us to examine the early transition of chalcids and their ground-plan relative to other early Proctotrupomorpha. Based on this study we provide palaeontological and morphological evidence for a late Cretaceous radiation in the superfamily and a modified hypothesis for the biogeographic origins of chalcid wasps. Based on the diversity of paleotaxa from the Cretaceous, an early, unsuccessful diversification event in the Cretaceous is hypothesized prior to the mega-radiation of the early Eocene. The presence of a “gap” in the paleocene record is also discussed and the utility of morphological data from the fossil record clarifies uncertainty in the parallelism versus secondary reversal in some characters in early crown-group lineages. Several ground-plan characters are confirmed from within the family, such as tarsal and antennomere counts, along with a putative plesiomorphy within Proctotrupomorpha of a strongly, proximally curving basal vein. In the second chapter, a metapleural gland is described from the parasitoid wasp Pelecinus polyturator. The unique gland is previously known only from Formicidae where it is hypothesized to be a key innovation in eusociality and an autapomorphy for the family. The gland is investigated both morphologically, behaviorally and chemically relative to the metapleural gland of ants. Hypotheses as to why the evolution of the gland was so impactful for ant diversification and less so for Pelecinidae are presented. The gland is shown to be the product of deep convergence within Hymenoptera due to a lack of transitional forms between the distantly related groups. Using this research as a basis, the “homology problem” of exocrine glands in insects is explored and formalized due to the presence of disparate evolutionary pathways occurring in a single organ system, the biosynthetic and morphological. Exaptation rather than adaptation is hypothesized to be the primary driver of glandular diversity in Hymenoptera. Within Pelecinidae, the gland ultrastructure and gross morphology is similar to that of the primitive ant lineages, suggesting a base form of the gland within Hymenoptera is present. The subsequent diversification and exaptation of the metapleural gland in Formicidae is hypothesized to be driven by eusociality, which is lacking in the asocial, parthenogenic pelecinids. A novel evolutionary model for examining exocrine glands is proposed with respect to underlying gene regulatory networks which signal the formation of exocrine glands in “hotspot” regions of the body while the biosynthetic pathways are highly homoplastic. Collectively, this work aims to elucidate the potential causes and effects of morphological “innovation” which leads to diversification in taxa. The examination of the earliest taxa of a hyper-diverse lineage provides insight into the ancestral states and morphology prior to radiation, and provides additional evidence for ground-plan characters. In lineages which have a dense radiation event such as Chalcidoidea, the transitionary forms of characters can be easily lost or obscured within a sparse fossil record, or overwhelmed by convergence and reversals across multiple lineages through time. Homoplasy can also be a boon for examining the impact of morphological innovation on diversification in a lineage relative to a convergent structure in a different group which is less successful.
  • Publication
    Regulation of fibroblast growth factor 23 (FGF23) in metabolic derangement
    (2024) Alber, Jana; Föller, Michael
    Increased incidence of metabolic syndrome is attributable to Western dietary patterns. Metabolic syndrome enhances risk of developing diabetes mellitus type 2 or cardiovascular diseases, which are associated with lactic acidosis, diabetic ketoacidosis and hyperhomocysteinemia. Increased lactate, ketone body or homocysteine levels are therefore relevant indicators of impaired metabolism and pathogenesis. FGF23 is an important regulator of calcitriol and phosphate homeostasis, and is predominantly synthesized in bone cells. Synthesis of FGF23 is regulated by various mechanisms including insulin/IGF1, mTOR, AMPK, PPARα, inflammation and oxidative stress. Increased FGF23 serum levels are correlated to inflammatory, renal and cardiovascular diseases, thus FGF23 represents an important therapeutic target and disease marker. Investigations unveiling regulation of FGF23 expression and synthesis as well as underlying mechanisms are therefore of high clinical significance. Hence, the present work aimed to elucidate a relevance of impaired metabolism on FGF23 formation, therefore establishing a basis for improved diagnosis as well as therapeutic approaches reducing morbidity and mortality in lactic acidosis, diabetic ketoacidosis or hyperhomocysteinemia. To this end, regulation of FGF23 synthesis under the influence of lactate, ketone bodies and homocysteine was analyzed. Lactic acid and sodium lactate enhanced Fgf23 expression in UMR106 osteoblast-like cells, an effect translated into higher cFGF23 concentration in cell culture supernatants. Application of NFκB inhibitors wogonin and withaferin A demonstrated an NFκB-mediated up-regulation of Fgf23 expression through lactic acid. Despite the knowledge that NFκB is an inducer of FGF23 formation and lactate stimulates NFκB activity, this study is the first to reveal a direct regulation of lactate on FGF23 production. As lactic acidosis is a common comorbidity in diabetes mellitus type 2 or cancer and increased lactate serum concentrations are associated with higher mortality, the findings of this study demonstrate FGF23 to be another useful biomarker for disease monitoring and prognosis. Furthermore homocysteine is a new regulator of FGF23 synthesis as shown within the present work, thus increasing Fgf23 expression and cFGF23 abundance in UMR106 cells. This effect is mediated by enhanced oxidative stress which stimulates FGF23 production, and is abolished by application of anti-oxidative ascorbic acid. Homocysteine serum levels are associated with versatile pathologies and its link to FGF23 signaling is therefore of clinical relevance, particularly in cardiovascular and renal diseases. In another investigation as part of this work, the ketone body βHB was identified as stimulator of FGF23 synthesis in UMR106 osteoblast-like cells as well as in primary cardiomyocytes, NRVM. Within NRVM, regulation of Fgf23 expression was shown to be dependent on MCT1/2 and HCAR2. Furthermore, intracellular activation of NFκB by βHB impacting on FGF23 synthesis was demonstrated in UMR106 cells. Moreover, short-term fasting (16 h) or βHB sodium salt administration increased FGF23 serum concentrations in C57BL/6 mice. These effects are of high relevance, since fasting-induced FGF23 synthesis was associated with lower NaPi-IIa and αklotho expression as well as with higher Cyp24a1 expression. In line with high FGF23 levels and enhanced Cyp24a1 expression, calcitriol serum levels of fasted animals were significantly lower compared to mice fed ad libitum. Other serum parameters including phosphate, calcium and PTH did not differ between both study groups. Further investigations revealed an important role of the heart as well as of thymus, spleen and pancreas in fasting-induced FGF23 synthesis. However, Fgf23 expression in bone and bone marrow did not differ between fasted mice and mice fed ad libitum, and was not detectable in liver tissue. As fasting and ketone body production are thought to be beneficial for various diseases and longevity, the findings of this investigation have enormous clinical implications. Since FGF23 has been demonstrated to be an important disease marker, and fasting induces FGF23 synthesis, blood samples of patients in fasting states may require careful interpretation. In conclusion, the present work is the first to demonstrate a direct regulation of FGF23 synthesis through lactate, ketone bodies and homocysteine. Hereby, NFκB signaling and generation of oxidative stress play a pivotal role. As FGF23 formation has been shown to be regulated through short-term fasting and to impact on phosphate homeostasis within the present work, the findings are highly implicated in physiology and pathophysiology. With respect to development of cardiovascular or renal diseases through lactic acidosis, diabetic ketoacidosis and homocysteinemia as well as to the relevance of FGF23 in these pathologies, the results of the present work are of significance for improved disease monitoring and establishment of new therapeutic approaches. Future investigations examining an involvement of metabolic regulators, e.g. insulin, mTOR, AMPK, PPARα, or of FGF co-receptor αklotho may provide further promising targets for therapy, diagnosis and prognosis of metabolic diseases.
  • Publication
    Einfluss von klimatischen Faktoren auf das Quartiernutzungsverhalten des Großen Mausohrs (Myotis myotis) in Deutschland
    (2024) Matthäus, Laura; Fietz, Joanna
    Um dem dramatischen Artenrückgang der letzten Jahrzehnte entgegenzuwirken und die Folgen des Klimawandels einschätzen und seine Auswirkungen bewerten zu können, ist es unerlässlich, die Auswirkungen der klimatischen Veränderungen auf die Fauna zu beobachten. Nur auf dieser Grundlage können wirksame Maßnahmen zum Schutz der Arten ergriffen werden. Auch bei den Fledermäusen kam es ab Mitte der 1950er Jahre zu einem massiven Rückgang der Populationen mehrerer europäischer Fledermausar- ten. Bei einer dieser Arten handelt es sich um das Große Mausohr (Myotis myotis), für welches Deutschland aufgrund der weltweiten Verbreitung der Art sowie der Verteilung der Weltpopulation eine besondere Verantwortung trägt. Um auf Basis der FFH- Richtlinie, in deren Anhang II und Anhang IV das Große Mausohr geführt wird, dauerhaft einen wirksamen Schutz der Art in Deutschland gewährleisten zu können, war das Ziel der vorliegenden Dissertation, den Einfluss klimatischer Faktoren auf das Quartiernut- zungsverhalten des Großen Mausohrs zu untersuchen und ein Konzept für ein kontinu- ierliches bundesweites Monitoringsystem zu entwickeln. Es wird angenommen, dass die Änderungen klimatischer Faktoren Einfluss auf den Energieverbrauch sowie die Nahrungsverfügbarkeit und damit auf das Nahrungssuch- verhalten, die Reproduktion und das Überleben bzw. die Bestandsentwicklung von Fle- dermäusen haben. Um die Hypothese validieren zu können, wurde zunächst untersucht, welche Erfassungsmethoden geeignete Daten hierfür liefern können. Dazu wurden visu- elle Ausflugszählungen, halbautomatisierte Infrarotvideoaufnahmen und vollautomati- sierte Lichtschrankenerfassungen an Großen Mausohr-Wochenstuben synchron durch- geführt. Anhand des Methodenvergleichs sollen zudem die ehrenamtlichen und professionellen Kartierer, Wissenschaftler sowie Fachbehörden in der Auswahl einer geeigneten Erhe- bungsmethode unterstützt werden. Da der Vergleich der Datenqualität ergeben hat, dass diesbezüglich keine signifikanten Unterschiede zwischen den drei angewandten Metho- den vorliegen und auch die Anwesenheit des Kartierers keinen Einfluss im Sinne einer Störung auf den Ausflug der Großen Mausohren hat, kann die Wahl der geeigneten Er- fassungsmethode fallspezifisch von den Rahmenbedingungen und der Zielsetzung der Studie abhängig gemacht werden. Im Fall des angestrebten bundesweiten Großen Mausohr-Monitorings zur Überwachung des Großen Mausohrbestands in Deutschland im Rahmen der FFH-Richtlinie empfiehlt sich die Durchführung von permanenten Lichtschrankenerfassungen, um anhand von Langzeitaufnahmen mögliche Bestandsveränderungen in den Wochenstuben unmittel- bar identifizieren und geeignete Maßnahmen ergreifen zu können. Bei Bedarf kann die Lichtschrankenerfassung, beispielsweise zur Validierung, stichprobenartig mit anderen Methoden kombiniert werden. Somit konnte anhand der Untersuchung zum Methoden- vergleich die Eignung der Methode der Lichtschrankenerfassung und die Validität der erzeugten Daten für die Untersuchung von Klimaeinflüssen auf die Phänologie bestätigt werden. In der Folge wurden auf Basis von Lichtschrankenerfassungen gewonnene Daten her- angezogen, um das Quartiernutzungsverhalten des Großen Mausohrs in Abhängigkeit von klimatischen Faktoren zu analysieren. Hierfür wurde ermittelt, ob die Umgebungs- temperatur (Ta) einen Einfluss auf die Phänologie des Großen Mausohrs hat. Die vorliegenden Untersuchungen haben gezeigt, dass Veränderungen der Ta einen maßgeblichen Einfluss auf die Phänologie der Großen Mausohren haben. Dabei kann sich eine Erhöhung der Ta je nach Zeitpunkt positiv oder negativ auf die Fitness der Fledermäuse auswirken. So scheinen warme Winter bis zu einer gewissen Temperatur eine frühere Rückkehr in die Wochenstuben auszulösen, was je nach den anhaltenden Witterungsbedingungen und damit der Insektenverfügbarkeit positiv oder negativ für die Fledermäuse sein kann. Ein warmes Frühjahr wiederum scheint zu einem früheren Start der Geburten zu führen, wodurch ausreichende Energiereserven für den Winterschlaf angelegt werden können. Auch hohe Temperaturen während der Laktation der Fleder- mäuse sowie ein früherer Start der Geburten führten zu einer früheren Auflösung der Wochenstube, sodass die Überwinterung der Jung- und Muttertiere günstigen Bedingun- gen unterliegt, da bereits frühzeitig Energiereserven gesammelt werden können. Nach diesen Ergebnissen ist es unerlässlich, bei der Entwicklung von Maßnahmen zum Schutz der Fledermausfauna den Einfluss der klimatischen Veränderungen auf die Fle- dermäuse miteinzubeziehen. Die Erkenntnisse aus dem Methodenvergleich sowie die Ergebnisse der Untersuchung zum Einfluss der Umgebungstemperatur auf die Phänologie des Großen Mausohr wer- den in einem die Dissertation abschließenden Monitoringkonzept angewendet. Dieses Konzept ist auf den Fledermausschutz sowie insbesondere den Schutz in den Quartie- ren ausgerichtet und sieht eine permanente Aktivitätserfassung mittels Lichtschranken- Technik vor. Es konnte ein Monitoringdesign entwickelt werden, welches bei eintreten- den Verhaltensänderungen in Wochenstuben des Großen Mausohrs das unmittelbare Ergreifen von Maßnahmen ermöglicht, wodurch ein schneller und wirksamer Schutz der Art gewährleistet werden kann. Darüber hinaus werden die erforderlichen Bestandsda- ten generiert, um der auf der FFH-Richtlinie basierenden Berichtspflicht gegenüber der EU vollumfänglich nachkommen zu können.
  • Publication
    Concerning the photophysics of fluorophores towards tailored bioimaging compounds: A case study involving S100A9 inflammation markers
    (2023) Steiner, Simon T.; Maisuls, Iván; Junker, Anna; Fritz, Günter; Faust, Andreas; Strassert, Cristian A.; Steiner, Simon T.; European Institute for Molecular Imaging, Westfälische Wilhelms-Universität Münster, Münster, Germany; Maisuls, Iván; Center for Nanotechnology, Westfälische Wilhelms-Universität Münster, Münster, Germany; Junker, Anna; European Institute for Molecular Imaging, Westfälische Wilhelms-Universität Münster, Münster, Germany; Fritz, Günter; Cellular Microbiology, Institute of Biology, University of Hohenheim, Stuttgart, Germany; Faust, Andreas; European Institute for Molecular Imaging, Westfälische Wilhelms-Universität Münster, Münster, Germany; Strassert, Cristian A.; Center for Nanotechnology, Westfälische Wilhelms-Universität Münster, Münster, Germany
    A full understanding concerning the photophysical properties of a fluorescent label is crucial for a reliable and predictable performance in biolabelling applications. This holds true not only for the choice of a fluorophore in general, but also for the correct interpretation of data, considering the complexity of biological environments. In the frame of a case study involving inflammation imaging, we report the photophysical characterization of four fluorescent S100A9-targeting compounds in terms of UV–vis absorption and photoluminescence spectroscopy, fluorescence quantum yields (ΦF) and excited state lifetimes (τ) as well as the evaluation of the radiative and non-radiative rate constants (kr and knr, respectively). The probes were synthesized based on a 2-amino benzimidazole-based lead structure in combination with commercially available dyes, covering a broad color range from green (6-FAM) over orange (BODIPY-TMR) to red (BODIPY-TR) and near-infrared (Cy5.5) emission. The effect of conjugation with the targeting structure was addressed by comparison of the probes with their corresponding dye-azide precursors. Additionally, the 6-FAM and Cy5.5 probes were measured in the presence of murine S100A9 to determine whether protein binding influences their photophysical properties. An interesting rise in ΦF upon binding of 6-FAM-SST177 to murine S100A9 enabled the determination of its dissociation equilibrium constant, reaching up to KD = 324 nM. This result gives an outlook for potential applications of our compounds in S100A9 inflammation imaging and fluorescence assay developments. With respect to the other dyes, this study demonstrates how diverse microenvironmental factors can severely impair their performance while rendering them poor performers in biological media, showing that a preliminary photophysical screening is key to assess the suitability of a particular luminophore.
  • Publication
    Haemosporidian parasite infections of Malagasy Philepittidae and Nectariniidae are driven by phylogeny rather than ecology
    (2023) Barbon, Hannah; Berthoud, Jean-Louis; Woog, Friederike; Musa, Sandrine
    The nectarivorous common sunbird asity (Neodrepanis coruscans) is phylogenetically closely related to the frugivorous velvet asity (Philepitta castanea), yet it shares similar habitat and foraging behaviour as the Malagasy sunbirds (Cinnyris spp.). As ecological factors have been shown to influence blood parasite prevalence, it should be tested whether parasite abundance, prevalence and diversity of N. coruscans are more similar to the sunbirds than to its relative. Therefore, blood samples (n = 156) and smears (n = 60) were tested for different blood parasites (Haemosporida, trypanosomes, filarioid nematodes) using molecular and microscopic methods. High prevalence of haemosporidian parasites was observed in all bird taxa, with rates ranging from 23% in N. coruscans to 84.6% in C. notatus. The Malagasy Cinnyris spp. exhibited a high occurrence of mixed haemosporidian infections (>76%) with various specialized lineages. Within the Philepittidae family, no Haemoproteus infection was detected and just a few cases of mixed infections. Nectariniidae species predominantly had specialized haemosporidian lineages, while Philepittidae had infections mainly caused by generalist lineages. These findings emphasize the diverse range of blood parasites in Nectariniidae, while additionally highlighting the high diversity of trypanosomes and filarioid nematodes in Philepittidae. Additionally, several newly discovered haemosporidian lineages, Trypanosoma isolates and filarioid nematode isolates were identified. Notably, Philepittidae exhibited a lower prevalence of avian haemosporidian parasites compared to Nectariniidae, possibly due to potential resistance mechanisms. Despite N. coruscans sharing similar habitat and behavioural ecology with both Cinnyris spp., it closely resembles its relative, P. castanea, in all aspects of haemosporidian parasitism.
  • Publication
    High genetic diversity of Echinococcus canadensis G10 in northeastern Asia: Is it the region of origin?
    (2023) Wassermann, Marion; Addy, Francis; Kokolova, Ludmila; Okhlopkov, Innokentiy; Leibrock, Sarah; Oberle, Jenny; Oksanen, Antti; Romig, Thomas
    Echinococcus canadensis consists of 4 genotypes: G6, G7, G8 and G10. While the first 2 predominantly infect domestic animals, the latter are sylvatic in nature involving mainly wolves and cervids as hosts and can be found in the northern temperate to Arctic latitudes. This circumstance makes the acquisition of sample material difficult, and little information is known about their genetic structure. The majority of specimens analysed to date have been from the European region, comparatively few from northeast Asia and Alaska. In the current study, Echinococcus spp. from wolves and intermediate hosts from the Republic of Sakha in eastern Russia were examined. Echinococcus canadensis G10 was identified in 15 wolves and 4 cervid intermediate hosts. Complete mitochondrial cytochrome c oxidase subunit 1 (cox1) sequences were obtained from 42 worm and cyst specimens from Sakha and, for comparison, from an additional 13 G10 cysts from Finland. For comparative analyses of the genetic diversity of G10 of European and Asian origin, all available cox1 sequences from GenBank were included, increasing the number of sequences to 99. The diversity found in northeast Asia was by far higher than in Europe, suggesting that the geographic origin of E. canadensis (at least of G10) might be northeast Asia.