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Towards synthetic catechol rich protein analogues through tyrosinase catalyzed activation of a tyrosine dipeptide in continuous mode
No full textWe present a perspective towards a green synthesis route for synthetic, catechol rich protein analogues (TCC). The method relies on the oxidation of a tyrosine dipeptide in continuous mode by the immobilized tyrosinase SinATyr followed by Michael addition of a dithiol. For the dipeptide substrate a kcat value of 0.16 s−1 and a Km value of 1.6 mM were determined meaning that its conversion is slower and the affinity towards the active center of the enzyme is lower compared to the standard substrate l-tyrosine (kcat = 5.6 s−1; Km = 0.24 mM). For the continuous operation mode SinATyr is immobilized on polyelectrolyte decorated silica microparticles with a k value of 0.11 s−1 (at 1 mM dipeptide substrate) after immobilization and finally experimental proof is given that the converted dipeptide in contact with the dithiol yields the desired TCC structures.Bundesministerium für Bildung und Forschung 10.13039/501100002347Austrian Science Fund 10.13039/501100002428Deutsche Forschungsgemeinschaft 10.13039/501100001659Peer Reviewe
Bedürfnisse und Anforderungen an Metadaten
No full textDiese Veröffentlichung geht zurück auf eine Masterarbeit im Studiengang Information Science, M. A. an der Humboldt-Universität zu Berlin aus dem Jahr 2025.Die Masterarbeit untersucht, welche Metadaten Geisteswissenschaftler*innen für eine effektive Nutzung von Web-Archiven benötigen. Im Mittelpunkt steht die Frage, welche Metadaten bereits vorhanden sind, wo Lücken bestehen und wie eine machbare Umsetzung erfolgen könnte. Durch leitfadengestützte Expert*inneninterviews wird ermittelt, welche spezifischen Metadaten von den Forschenden als notwendig erachtet werden, um Web-Archive besser für Forschungszwecke nutzen zu können. Die Ergebnisse der Arbeit zeigen, dass eine zeitnahe Bereitstellung der identifizierten Metadaten essenziell ist, um eine nachhaltige, gute und wissenschaftliche Nutzung von Web-Archiven zu ermöglichen
Temperature-induced heart arrhythmias
No full textDiese Abhandlung befasst sich mit Temperatureinflüssen auf Nervensysteme.Dabei geht es um die elektrischen Signale, wie sie z. B. in Neuronen und Herzzellen zu finden sind. Diese Abhandlung liefert einen Überblick über die zu Grunde liegenden biophysikalischen Prozesse, die sich daraus ergebenen Temperaturabhängigkeiten aller bekannten elektrophysiologischen Parameter und in welchen Situationendiese eine Rolle spielen für den Organismus selbst als auch für die Forschung im Allgemeinen. Ein besonderes Augenmerk liegt dabei auf temperaturinduzierten Krankheitsbildern wie z. B. dem Brugada-Syndrom. Die zentrale Frage dieser Abhandlung ist, wie Veränderungen der einzelnen Ionenkanalparameter (z. B. wegen Mutationen) die Temperaturabhängigkeit des Aktionspotenzials beeinflussen. Diese Frage wird erst im Allgemeinen behandelt. Nach einer Zusammenfassung, wie Temperaturabhängigkeit in mathematischen Modellen berücksichtigt werden kann (und sollte), wird am Beispiel des berühmten Hodgkin-Huxley Models die resultierende Temperaturabhängigkeit des Aktionspotenzials und der allgemeine Einfluss der einzelnen Modellparameter auf diese Temperaturabhängigkeit erläutert. Dann wird dieses Wissen konkret auf das Thema von fieberinduzierten Herzarrhythmien übertragen, welche durch bestimmte Natriumkanal-Mutationen ausgelöst werden können. Mithilfe des mathematischen Modells einer menschlichen Herzzelle wird untersucht, inwiefern die verschiedenen Natriumkanal-Parameter das Ruhepotenzial und die Form des Aktionspotenzials beeinflussen.Temperature influences the electrical signals found in neurons and heart cells. This thesis provides an overview of the underlying biophysical processes, the resulting temperature dependence of the electrophysiological parameters, and situations in which these play a role for the organism and the researchers studying this organism. A special focus will be on temperature-induced diseases like the Brugada syndrome. The main question of this thesis is how the change in the individual ion channel parameters (e.g., due to mutations) influences the temperature dependence of the action potential. At first, this question is discussed more generally. After a summary of how temperature dependence can (and should) be included in mathematical models, the resulting temperature dependence of the action potential and the general influence of the individual model parameters on this temperature dependence are explained using the famous Hodgkin-Huxley model as an example. This knowledge is then transferred to the topic of fever-induced cardiac arrhythmias, which can be triggered by specific sodium channel mutations. Many studies focus on the late sodium current for the medical treatment of fever- induced heart arrhythmias. The model results presented here show that other sodium channel parameters, like the shifts in the activation and inactivation curve’s voltage dependence, also have the potential to trigger temperature-induced heart arrhythmias. Using a mathematical model for human ventricular cells, the extent to which the various sodium channel parameters can change the resting membrane potential (the voltage difference between the cell’s interior and exterior in the absence of electrical signals) and the shape of the action potential is investigated
The potential of cashew by-product processing for a more sustainable agri-food system
No full textIn most cashew-producing countries, cashew apples, by-products of cashew nut production, remain largely unused despite their nutritional value. Similarly, cashew nut shells, a by-product of nut processing, are often wasted, even though they contain a toxic liquid (cashew nut shell liquid, CNSL) which can pollute the soil but has industrial applications in paint, varnish, and pesticide production. The residual cake left after CNSL extraction can be used to generate bioenergy and biofertilizer. This study analyzes the effects of enhancing the processing of these cashew by-products in Benin using a single-country Computable General Equilibrium model. Based on an empirical study we identify a high potential domestic demand for cashew apple juice indicating a potential to utilize currently wasted cashew apples. A key novelty of our work lies in the extension of the General Equilibrium model to incorporate “unemployed intermediate inputs” (here cashew by-products). Our findings reveal that stimulating demand for cashew apple juice can catalyze growth in the cashew-apple-processing sector and incentivize cashew farming. In addition, targeted subsidies for promoting the cashew-apple-processing sector could further support sectoral development and enhance cashew apple utilization. These developments result in reductions of waste, land use per calorie, trade deficit, and poverty, while increasing domestic value-added, household income, and nutritional security. These findings reflect circular economy principles by showing how waste becomes value, closing loops in the agri-food system. Overall, this study highlights the potential of processing cashew by-products for enhancing the economic, social, and environmental sustainability of the agri-food system.Open Access funding enabled and organized by Projekt DEAL.Humboldt-Universität zu Berlin (1034)Peer Reviewe
Unterstützte Kommunikation in den Disziplinen: Medizin, Pädagogik, Therapie und Pflege - Zwischen der Arbeit in der eigenen Disziplin und der Interdisziplinarität Tagebuch zur Förderung der Interdisziplinarität (TFI)
No full textFür die erfolgreiche Umsetzung Unterstützter Kommunikation (UK) im Alltag ist die enge Zusammenarbeit von Medizin, Therapie, Pflege, Pädagogik und dem sozialen Umfeld entscheidend. Interdisziplinäre Treffen bilden dabei eine zentrale Grundlage. Das Forschungsprojekt ist eine deskriptive Evaluationsstudie als bottom up Forschungsdesign, analysiert durch eine exploratives sequentielles Mixed-Methode-Design. Ziel des Forschungsprojekts die Interdisziplinarität in der Unterstützten Kommunikation zu fördern. Aus diesem Hintergrund entstand die Idee ein Tagebuch zur Förderung der Interdisziplinarität (TFI) zwischen den vier primären Disziplinen. Ziel des TFI ist es, durch effiziente Vorbereitung und kontinuierlichen Austausch die Ressourcen der Fachkräfte zu schonen und die Umsetzung Unterstützter Kommunikation zu fördern. Zur Beantwortung der Forschungsfrage und Optimierung des TFI wurden 17 Expert:inneninterviews durchgeführt, das Tagebuch in zwölf Fallstudien erprobt und durch Fachkräfte bewertet. Ergänzend beantworteten 179 Personen deutschlandweit einen Fragebogen zu Unterstützter Kommunikation und Interdisziplinarität. Die Ergebnisse zeigen, dass organisatorische (u.a. Ressourcenmangel und fehlende Ausbildungsmöglichkeiten), soziale (u.a. fehlende Kommunikation und Wertschätzung) und persönliche Faktoren (u.a. fehlende Motivation und Fachwissen) sowie die Überforderung der Angehörigen einen starken Einfluss auf die Interdisziplinarität und die Umsetzung Unterstützter Kommunikation haben. Obwohl das TFI positiv bewertet wurde, erschwerten diese Faktoren seine Umsetzung. Zukunftsorientiert ist eine digitale Version des TFIs zur Förderung der Umsetzung Unterstützter Kommunikation sowie Interdisziplinarität zwischen der eigenen Arbeit der Fachkräfte und den interdisziplinären Treffen unabdingbar.For the successful implementation of augmentative and alternative communication (AAC), is it essential that the disciplines medicine, therapy, care and education as well as the immediate social environment work together and build on each other, requiring interdisciplinary meetings and regular exchanges. The research project is a descriptive evaluation study with a bottom up research design, analyzed by an explorative sequential mixed method. The aim is to conserve the resources of the professionals and promote the implementation of AAC. This gave rise to the idea of developing a diary to promote interdisciplinarity – “Tagebuch zur Förderung der Interdisziplinarität” (TFI) between the four primary disciplines (medicine, education, therapy and care). Specifically, the goal of the TFI is to prepare the interdisciplinary meetings effectively and to be able to work effectively in the time between one's own work and the interdisciplinary meetings through constant exchange. To optimize the TFI, 17 expert interviews were conducted, followed by practical testing with twelve participants and professional evaluation. Additionally, a nationwide questionnaire on AAC and interdisciplinarity gathered responses from 179 users, caregivers, and professionals. Organizational factors (e.g., lack of time and bureaucracy), social factors (e.g., poor communication between specialists and lack of recognition), and personal factors (e.g., low motivation or insufficient knowledge), along with relatives’ feelings of helplessness, strongly affect AAC implementation and interdisciplinarity. Despite these challenges, the TFI was positively received, though difficulties in applying it remained. Looking to the future, a digital version of the TFI is essential to promote the implementation of AAC and interdisciplinarity between the professionals' own work and the interdisciplinary meetings
Myosin VI controls localization of golgi satellites at active presynaptic boutons
No full textNeurons, as long-lived non-dividing cells with complex morphology, depend on a highly elaborate secretory trafficking system which enables a constant turnover of proteins and membranes. Previously, it was shown that simplified, Golgi-related structures called Golgi satellites (GS) are present in the dendrites of primary hippocampal neurons. These organelles are distinct from the somatic Golgi complex and are involved in de novo glycosylation and local forward trafficking of membrane proteins. However, the question of whether GS are also targeted to the axons of principal neurons remained unanswered. In this study, we investigated the subcellular distribution of GS in adult hippocampal neurons. Our findings showed that GS are present all along the axon, extending to the distal tips of the growth cone. Similar to dendritic GS, the axonal organelles are labeled by the same GS markers and are capable of mature glycosylation. Live imaging experiments revealed the presence of both mobile and immobile GS in the axon, and that the switch between active transport and stalling of GS was modulated by neuronal firing. We found that GS frequently pause at en passant synapses and remain stationary for longer time periods at activated pre-synaptic boutons. This behavior is dependent on the actin cytoskeleton and the actin-based motor protein myosin VI. Overall, our study demonstrates that neuronal activity can dynamically regulate the positioning of GS in the axon, shedding light on the intricate mechanisms underlying organelle trafficking in neurons.Open Access funding enabled and organized by Projekt DEAL.Humboldt-Universität zu Berlin (1034)Peer Reviewe
Redox regulation of glutamate-1-semialdehyde aminotransferase modulates the synthesis of 5-aminolevulinic acid in Arabidopsis
No full textThe article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Plants are constantly exposed to sudden changes in environmental parameters and must respond quickly to changes in temperature, humidity and light conditions. Such fluctuations in growth conditions also require almost immediate adjustments in the synthesis of photosynthetic pigments. Post-translational redox control of tetrapyrrole metabolism for chlorophyll and heme synthesis provides the necessary modifications for photosynthesis. The enzyme glutamate-1-semialdehyde aminotransferase (GSAAT) contributes to the rate-limiting step in the synthesis of 5-aminolevulinic acid (ALA). We intend to specifically investigate the redox control of GSAAT, analyze the redox-dependent shifts in the thiol-disulphide state of GSAAT, and identify the redox-dependent cysteines responsible for changes in the structure, enzymatic activity and stability of the protein. Wild-type GSAAT and Cys→Ser substitution mutants of the enzyme were examined for their activities with the labile substrate of GSAAT, glutamate-1-semialdehyde, which was synthesized in a simplified manner using a novel method. We show that of the four cysteine residues found in GSAAT, Cys168 and Cys190 are crucial for the redox-regulated state of GSAAT. Based on these experiments, we propose a redox-dependent structural modification of GSAAT that could lead to a decrease in the activity of the oxidized protein compared to the reduced enzyme.Peer Reviewe
Single cell transcriptional profiling of dry and wet season Plasmodium falciparum
No full textMalaria bleibt eine erhebliche globale Gesundheitsbelastung mit geschätzten 249 Mio. Fällen und über 600.000 Todesfällen im Jahr 2022. Die Krankheit wird durch Plasmodium-Parasiten verursacht und von weiblichen Anopheles-Mücken übertragen. Plasmodium falciparum ist der gefährlichste Erreger und für die meisten Todesfälle verantwortlich. Während seines 48-stündigen intraerythrozytären Entwicklungszyklus (IDC) sequestriert P. falciparum infizierte rote Blutkörperchen (iRBCs) durch Adhärenz an das Gefäßendothel, um der Milzentfernung zu entgehen. In vielen endemischen Regionen erfolgt die Übertragung saisonal. Während der Trockenzeit persistiert P. falciparum meist asymptomatisch bei niedriger Parasitämie und bleibt so bis zur Rückkehr der Mücken erhalten. Dabei zirkulieren iRBCs länger im IDC und haften seltener als in klinischen Regenzeitfällen. Diese Arbeit untersuchte den Zusammenhang zwischen Zirkulationszeit von iRBCs und Malariasymptomatik über saisonale Vergleiche hinaus sowie die transkriptionelle Regulation, die Trockenzeit-Persistenz ermöglicht. Hierzu wurden veröffentlichte Transkriptomdaten aus Studien mit unterschiedlichen Parasitämien reanalysiert. Zwei bioinformatische Methoden zur IDC-Stadiumsschätzung zeigten: Längere iRBC-Zirkulation tritt bei niedriger Parasitämie oder milder Erkrankung auf. Parasitenmessungen bestätigten diese Assoziation. Ein Single-Cell-Atlas mit >26.000 iRBCs aller Blutstadien ermöglichte präzises Stadium-Matching. Trockenzeit-iRBCs zeigten verlängerte Zirkulation und Hochregulation cytoadhäsionsbezogener Gene. Adhäsionsveränderungsexperimente replizierten diese Profile nicht, Temperaturerhöhungen hingegen teilweise. Diese Ergebnisse legen nahe, dass verringerte Adhäsion asymptomatische Infektionen bei niedriger Parasitämie fördert – unterstützt durch adaptive Genexpression, die P. falciparum das Überleben in der Trockenzeit ermöglicht.Malaria remains a major global health burden, with 249 million cases and over 600,000 deaths in 2022. It is caused by Plasmodium parasites, transmitted by female Anopheles mosquitoes. Plasmodium falciparum is the most deadly species, responsible for most fatal cases. During its 48-hour intra-erythrocytic developmental cycle (IDC), P. falciparum promotes sequestration of infected red blood cells (iRBCs) to the vascular endothelium, avoiding splenic clearance. In endemic regions, transmission is seasonal. In the dry season, P. falciparum persists at low parasitaemias and is often asymptomatic, ensuring survival until mosquitoes return. In these infections, iRBCs circulate longer during each IDC and adhere less compared to wet season cases. This thesis investigated how iRBC circulation time relates to malaria symptoms beyond seasonal differences, and identified gene regulation supporting dry season persistence. We reanalysed transcriptome datasets from multiple studies with varying parasitaemias and symptoms. Using two bioinformatic tools to estimate IDC stage composition, we found that iRBC circulation time increases as parasitaemia and disease severity decrease. Parasite size data supported this, showing that disease severity correlates with iRBC stage composition. We created a single-cell transcriptome atlas of >26,000 iRBCs spanning all blood stages, enabling accurate stage-matching. Analysis of dry vs wet season infections confirmed longer circulation of dry season iRBCs and revealed up-regulation of cytoadhesion-related genes in dry season cases. Experimentally altering iRBC adhesion did not reproduce these gene differences, but increased temperatures partially mimicked wet vs dry season profiles. These results suggest reduced iRBC adhesion leads to low parasitaemia and asymptomatic infection, highlighting gene expression changes that help P. falciparum persist through the dry season
Quantitative wood anatomy of Juniperus excelsa from Lebanon as a potential hydroclimate archive
No full textThe Middle East and North Africa is a hotspot for negative climate change impacts and potentially for conflicts over water resources. To protect future generations from destabilization and marginalization, governments need to consider the impact of climate change on water management issues. Long-term hydroclimatic information is needed for a reliable management of the water resources. However, only a few continuous high-quality meteorological records exist in MENA starting in the early 1900s, while the majority of existing records cover just the second half of the twentieth century, hence alternative sources such as tree-ring proxies to describe past climate dynamics will be a valuable add-on. Tree-ring width records of Greek juniper ( Juniperus excelsa M. Bieb) have already been demonstrated to be useful for extending existing instrumental climate records. For the first time, we investigated the dendroclimatological potential of J. excelsa growing in the Lebanese mountains, focusing, also for the first time, on quantitative wood anatomy. We measured cell lumen diameter in radial direction and cell wall thickness in tangential direction for the tree rings formed during the years 1963 to 2019. The measurements were then correlated with monthly and seasonal climate records. Strongest correlations were found between lumen diameter and current May precipitation (positive) as well as maximum temperature (negative). Lumen diameter also exhibited significant correlations with drought during May and July to September). Climate correlations with tree-ring width were generally less significant. The study showed, for the first time, declining trends in the cell lumen and cell wall data since the early 1990s suggesting that in the Lebanese Mountains this important tree species J. excelsa seems to have been under increasing drought stress. The preliminary findings highlight the feasibility of building long chronologies of quantitative wood anatomical parameters for J. excelsa from the Lebanese mountains and the potential of such measurements as a paleoclimate archive, especially when focusing on water availability and drought patterns.Peer Reviewe