Systems Biology of Fungal Infection

Elucidation of pathogenicity mechanisms of the most important human-pathogenic fungi, Aspergillus fumigatus and Candida albicans, has gained great interest in the light of the steadily increasing number of cases of invasive fungal infections. A key feature of these infections is the interaction of the different fungal morphotypes with epithelial and immune effector cells in the human host. Because of the high level of complexity, it is necessary to describe and understand invasive fungal infection by taking a systems biological approach, i.e., by a comprehensive quantitative analysis of the non-linear and selective interactions of a large number of functionally diverse, and frequently multifunctional, sets of elements, e.g., genes, proteins, metabolites, which produce coherent and emergent behaviors in time and space. The recent advances in systems biology will now make it possible to uncover the structure and dynamics of molecular and cellular cause-effect relationships within these pathogenic interactions. We review current efforts to integrate omics and image-based data of host-pathogen interactions into network and spatio-temporal models. The modeling will help to elucidate pathogenicity mechanisms and to identify diagnostic biomarkers and potential drug targets for therapy and could thus pave the way for novel intervention strategies based on novel antifungal drugs and cell therapy

Integrative analysis of the heat shock response in Aspergillus fumigatus

<p>Abstract</p> <p>Background</p> <p><it>Aspergillus fumigatus </it>is a thermotolerant human-pathogenic mold and the most common cause of invasive aspergillosis (IA) in immunocompromised patients. Its predominance is based on several factors most of which are still unknown. The thermotolerance of <it>A. fumigatus </it>is one of the traits which have been assigned to pathogenicity. It allows the fungus to grow at temperatures up to and above that of a fevered human host. To elucidate the mechanisms of heat resistance, we analyzed the change of the <it>A. fumigatus </it>proteome during a temperature shift from 30°C to 48°C by 2D-fluorescence difference gel electrophoresis (DIGE). To improve 2D gel image analysis results, protein spot quantitation was optimized by missing value imputation and normalization. Differentially regulated proteins were compared to previously published transcriptome data of <it>A. fumigatus</it>. The study was augmented by bioinformatical analysis of transcription factor binding sites (TFBSs) in the promoter region of genes whose corresponding proteins were differentially regulated upon heat shock.</p> <p>Results</p> <p>91 differentially regulated protein spots, representing 64 different proteins, were identified by mass spectrometry (MS). They showed a continuous up-, down- or an oscillating regulation. Many of the identified proteins were involved in protein folding (chaperones), oxidative stress response, signal transduction, transcription, translation, carbohydrate and nitrogen metabolism. A correlation between alteration of transcript levels and corresponding proteins was detected for half of the differentially regulated proteins. Interestingly, some previously undescribed putative targets for the heat shock regulator Hsf1 were identified. This provides evidence for Hsf1-dependent regulation of mannitol biosynthesis, translation, cytoskeletal dynamics and cell division in <it>A. fumigatus</it>. Furthermore, computational analysis of promoters revealed putative binding sites for an AP-2alpha-like transcription factor upstream of some heat shock induced genes. Until now, this factor has only been found in vertebrates.</p> <p>Conclusions</p> <p>Our newly established DIGE data analysis workflow yields improved data quality and is widely applicable for other DIGE datasets. Our findings suggest that the heat shock response in <it>A. fumigatus </it>differs from already well-studied yeasts and other filamentous fungi.</p

Kompetenzerwerb im Physikunterricht: eine interessenbezogene Unterrichtsintervention in der Sekundarstufe I

Die vorliegende Dissertationsschrift stellt die Ergebnisse einer quasi-experimentellen Studie im Physikunterricht der Sekundarstufe I an Thüringer Gymnasien vor. Ziel der Studie war es, die unterstützende Wirkung der Einbindung individuell interessierender Themen in den Unterricht auf den fachspezifischen Kompetenzerwerb empirisch zu bestätigen. Dafür wurden für eine Stichprobe von insgesamt 115 Lernenden 60 Lernende in der Treatmentgruppe (TG) und 55 Lernende in der Kontrollgruppe (KG) Unterrichtsmaterialien zum Themengebiet Halbleiter entwickelt, welche eine vergleichende Beobachtung von Unterricht mit (TG) vs. ohne (KG) Einbeziehung von individuellen, auch fachfremden Interessengebieten der Lernenden ermöglichten. Neben der Erhebung von fachspezifischen Lernvoraussetzungen und der Ausprägung des situationalen Interesses während der Unterrichtsreihe zu vier Messzeitpunkten wurde vor und nach der Unterrichtsreihe die Kompetenz im Fachwissensbereich Elektrizitätslehre erfasst. Bezugnehmend auf die pädagogische Theorie des Interesses wurde nach der interessenbezogenen Unterrichtsreihe ein höherer Kompetenzwert erwartet. Lernende in der TG zeigten über den Verlauf der Intervention ein höheres situationales Interesse und hypothesenkonform insbesondere im Bereich höherer Komplexität einen beobachtbaren Effekt in der Ausprägung des untersuchten Kompetenzbereiches gegenüber der KG. Dabei ließen sich innerhalb der TG, im Gegensatz zur KG, keine statistisch signifikanten Zusammenhänge zwischen dem erreichten Kompetenzwert und ausgewählten fachspezifischen Lernvoraussetzungen erkennen. Somit konnte im Rahmen der Intervention gezeigt werden, dass durch die Integration individueller auch fachfremder Interessen in den Physikunterricht ungünstige fachspezifische Ausgangsbedingungen überwunden werden können. Die Zusammenhänge und Ergebnisse bestätigen die angenommene Bedeutung individueller, auch fachfremder Interessenbezüge für den fachspezifischen Kompetenzerwerb

Conidial Dihydroxynaphthalene Melanin of the Human Pathogenic Fungus Aspergillus fumigatus Interferes with the Host Endocytosis Pathway

Aspergillus fumigatus is the most important air-borne fungal pathogen of humans. The interaction of the pathogen with the host's immune system represents a key process to understand pathogenicity. For elimination of invading microorganisms, they need to be efficiently phagocytosed and located in acidified phagolysosomes. However, as shown previously, A. fumigatus is able to manipulate the formation of functional phagolysosomes. Here, we demonstrate that in contrast to pigmentless pksP mutant conidia of A. fumigatus, the gray-green wild-type conidia inhibit the acidification of phagolysosomes of alveolar macrophages, monocyte-derived macrophages, and human neutrophil granulocytes. Therefore, this inhibition is independent of the cell type and applies to the major immune effector cells required for defense against A. fumigatus. Studies with melanin ghosts indicate that the inhibitory effect of wild-type conidia is due to their dihydroxynaphthalene (DHN)-melanin covering the conidia, whereas the hydrophobin RodA rodlet layer plays no role in this process. This is also supported by the observation that pksP conidia still exhibit the RodA hydrophobin layer, as shown by scanning electron microscopy. Mutants defective in different steps of the DHN-melanin biosynthesis showed stronger inhibition than pksP mutant conidia but lower inhibition than wild-type conidia. Moreover, A. fumigatus and A. flavus led to a stronger inhibition of phagolysosomal acidification than A. nidulans and A. terreus. These data indicate that a certain type of DHN-melanin that is different in the various Aspergillus species, is required for maximal inhibition of phagolysosomal acidification. Finally, we identified the vacuolar ATPase (vATPase) as potential target for A. fumigatus based on the finding that addition of bafilomycin which inhibits vATPase, led to complete inhibition of the acidification whereas the fusion of phagosomes containing wild-type conidia and lysosomes was not affected

Phagocytosis of Aspergillus fumigatus conidia by murine macrophages involves recognition by the dectin-1 beta-glucan receptor and Toll-like receptor 2

Aspergillus fumigatus is a fungal pathogen causing severe infections in immunocompromised patients. For clearance of inhaled conidia, an efficient response of the innate immune system is required. Macrophages represent the first line of defence and ingest and kill conidia. C-type lectins represent a family of receptors, which recognize pathogen-specific carbohydrates. One of them is beta1-3 glucan, a major component of the fungal cell wall. Here we provide evidence that beta1-3 glucan plays an important role for the elimination of A. fumigatus conidia. Laminarin, a soluble beta1-3 glucan and antibodies to dectin-1, a well known beta1-3 glucan receptor, significantly inhibited conidial phagocytosis. On resting conidia low amounts of surface accessible beta1-3 glucan were detected, whereas high amounts were found on small spores that appear early during germination and infection as well as on resting conidia of a pksP mutant strain. Swollen conidia also display larger quantities of beta1-3 glucan, although in an irregular spotted pattern. Resting pksP mutant conidia and swollen wild-type conidia are phagocytosed with high efficiency thereby confirming the relevance of beta1-3 glucans for conidial phagocytosis. Additionally we found that TLR2 and the adaptor protein MyD88 are required for efficient conidial phagocytosis, suggesting a link between the TLR2-mediated recognition of A. fumigatus and the phagocytic response

Convergence analysis of a multigrid algorithm for the acoustic single layer equation

We present and analyze a multigrid algorithm for the acoustic single layer equation in two dimensions. The boundary element formulation of the equation is based on piecewise constant test functions and we make use of a weak inner product in the multigrid scheme as proposed in \cite{BLP94}. A full error analysis of the algorithm is presented. We also conduct a numerical study of the effect of the weak inner product on the oscillatory behavior of the eigenfunctions for the Laplace single layer operator

High Flashpoint and Eco-Friendly Electrolyte Solvent for Lithium-Ion Batteries

Since Sony launched the commercial lithium-ion cell in 1991, the composition of the liquid electrolytes has changed only slightly. The electrolyte consists of highly flammable solvents and thus poses a safety risk. Solid-state ion conductors, classified as non-combustible and safe, are being researched worldwide. However, they still have a long way to go before being available for commercial cells. As an alternative, this study presents glyceryl tributyrate (GTB) as a flame retardant and eco-friendly solvent for liquid electrolytes for lithium-ion cells. The remarkably high flashpoint ($_{FP}$=174 °C) and the boiling point ($_{BP}$=287 °C) of GTB are approximately 150 K higher than that of conventional linear carbonate components, such as ethyl methyl carbonate (EMC) or diethyl carbonate (DEC). The melting point ($_{MP}$=−75 °C) is more than 100 K lower than that of ethylene carbonate (EC). A life cycle test of graphite/NCM with 1 M LiTFSI dissolved in GTB:EC (85:15 wt) achieved a Coulombic efficiency of above 99.6% and the remaining capacity resulted in 97% after 50 cycles (/4) of testing. The flashpoint of the created electrolyte is $_{FP}$=172 °C and, therefore, more than 130 K higher than that of state-of-the-art liquid electrolytes. Furthermore, no thermal runaway was observed during thermal abuse tests. Compared to the reference electrolyte LP40, the conductivity of the GTB-based is reduced, but the electrochemical stability is highly improved. GTB-based electrolytes are considered an interesting alternative for improving the thermal stability and safety of lithium-ion cells, especially in low power-density applications