Publications by authors named "Jahn R"

Article Synopsis
  • This chapter outlines an optimized protocol for isolating synaptic vesicles (SVs) from human induced pluripotent stem cell-derived neurospheres, beginning with the cultivation of mature neurons for functional studies.
  • The process involves isolating neurosphere-derived synaptosomes and enriching SVs through differential centrifugation.
  • Finally, the protocol utilizes nanoLC-MS/MS for proteomic analysis of SVs, aiding in the understanding of SV molecular diversity and neurotransmitter dynamics, with potential applications in neurological and neuropsychiatric research.
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Neuronal exocytosis requires the assembly of three SNARE proteins, syntaxin and SNAP25 on the plasma membrane and synaptobrevin on the vesicle membrane. However, the precise steps in this process and the points at which assembly and fusion are controlled by regulatory proteins are unclear. In the present work, we examine the kinetics and intermediate states during SNARE assembly in vitro using a combination of time resolved fluorescence and EPR spectroscopy.

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Background: Legislation in the European Union (EU) and the USA promoting the development of paediatric medicines has contributed to new treatments for children. This study explores how such legislation responds to paediatric health needs in different country settings and globally, and whether it should be considered for wider implementation.

Methods: We searched EU and US regulatory databases for medicines with approved indications resulting from completed paediatric development between 2007 and 2018.

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Background: Epidemiological studies in refugee settings are often challenged by the denominator problem, i.e. lack of population at risk data.

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In the secretory pathway the destination of trafficking vesicles is determined by specific proteins that, with the notable exception of SNAREs, are recruited from soluble pools. Previously we have shown that microinjected proteoliposomes containing early or late endosomal SNAREs, respectively, are targeted to the corresponding endogenous compartments, with targeting specificity being dependent on the recruitment of tethering factors by some of the SNAREs. Here, we show that targeting of SNARE-containing liposomes is refined upon inclusion of polyphosphoinositides and Rab5.

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We study the formation of vesicle condensates induced by the protein synapsin, as a cell-free model system mimicking vesicle pool formation in the synapse. The system can be considered as an example of liquid-liquid phase separation (LLPS) in biomolecular fluids, where one phase is a complex fluid itself consisting of vesicles and a protein network. We address the pertinent question why the LLPS is self-limiting and stops at a certain size, i.

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In neuronal cell types, vesicular exocytosis is governed by the SNARE (soluble NSF attachment receptor) complex consisting of synaptobrevin2, SNAP25, and syntaxin1. These proteins are required for vesicle priming and fusion. We generated an improved SNAP25-based SNARE COmplex Reporter (SCORE2) incorporating mCeruelan3 and Venus and overexpressed it in SNAP25 knockout embryonic mouse chromaffin cells.

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In the ear, inner hair cells (IHCs) employ sophisticated glutamatergic ribbon synapses with afferent neurons to transmit auditory information to the brain. The presynaptic machinery responsible for neurotransmitter release in IHC synapses includes proteins such as the multi-C-domain protein otoferlin and the vesicular glutamate transporter 3 (VGluT3). Yet, much of this likely unique molecular machinery remains to be deciphered.

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THRB is a nuclear receptor, regulating gene expression dependent on thyroid hormone (TH) binding. The same receptor mediates signaling pathway activation in the cytosol. The challenge is to distinguish which of the two mechanisms is responsible for physiological effects of TH.

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In neurons, autophagosome biogenesis occurs mainly in distal axons, followed by maturation during retrograde transport. Autophagosomal growth depends on the supply of membrane lipids which requires small vesicles containing ATG9, a lipid scramblase essential for macroautophagy/autophagy. Here, we show that ATG9-containing vesicles are enriched in synapses and resemble synaptic vesicles in size and density.

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Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are a family of small conserved eukaryotic proteins that mediate membrane fusion between organelles and with the plasma membrane. SNAREs are directly or indirectly anchored to membranes. Prior to fusion, complementary SNAREs assemble between membranes with the aid of accessory proteins that provide a scaffold to initiate SNARE zippering, pulling the membranes together and mediating fusion.

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Background: Refugees in collective accommodation facilities are at increased risk of COVID-19-infections due to high occupancy density and shared spaces. It is unclear which (organisational) actors the reception authorities were working with in their crisis response and how. The aim of this paper is to examine the working arrangements between reception authorities and other actors involved in accommodation and (health) care during the first wave of the COVID-19 pandemic and to derive recommendations for future crisis responses.

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The neuronal SNARE protein SNAP25a (isoform 2) forms part of the SNARE complex eliciting synaptic vesicle fusion during neuronal exocytosis. While the post-fusion cis-SNARE complex has been studied extensively, little is known about the pre-fusion conformation of SNAP25a. Here we analyze monomeric SNAP25a by NMR spectroscopy, further supported by small-angle X-ray scattering (SAXS) experiments.

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Objectives: In many high-income countries, structural, legal, social and political barriers to adequate healthcare interfere with the ability of health professionals to respond to the healthcare needs of a fluctuating and superdiverse population of asylum seekers. However, the relationship between individual, interpersonal and structural factors is not well understood. We explore the views and experiences of physicians working with asylum seekers in Germany and aim to identify how these may impact the provision of medical care.

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Vacuolar-type adenosine triphosphatases (V-ATPases) are electrogenic rotary mechanoenzymes structurally related to F-type ATP synthases. They hydrolyse ATP to establish electrochemical proton gradients for a plethora of cellular processes. In neurons, the loading of all neurotransmitters into synaptic vesicles is energized by about one V-ATPase molecule per synaptic vesicle.

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The size, polydispersity, and electron density profile of synaptic vesicles (SVs) can be studied by small-angle X-ray scattering (SAXS), i.e. by X-ray diffraction from purified SV suspensions in solution.

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Vesicular transporters (VTs) define the type of neurotransmitter that synaptic vesicles (SVs) store and release. While certain mammalian neurons release multiple transmitters, it is not clear whether the release occurs from the same or distinct vesicle pools at the synapse. Using quantitative single-vesicle imaging, we show that a vast majority of SVs in the rodent brain contain only one type of VT, indicating specificity for a single neurotransmitter.

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Cytotoxic T lymphocytes (CTL) kill malignant and infected cells through the directed release of cytotoxic proteins into the immunological synapse (IS). The cytotoxic protein granzyme B (GzmB) is released in its soluble form or in supramolecular attack particles (SMAP). We utilize synaptobrevin2-mRFP knock-in mice to isolate fusogenic cytotoxic granules in an unbiased manner and visualize them alone or in degranulating CTLs.

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Refugees and asylum seekers living in reception centres tend to be not adequately included in population-based studies, routine medical data and official statistics. As part of the research project 'Health and primary-care sentinel surveillance in reception- and accommodation-centres for asylum-seekers in Germany' (PriCare), a health-monitoring approach was developed for the secondary use of routine medical data from on-site outpatient clinics in reception centres. To this end, a software application (Refugee Care Manager, RefCare©) for the digitisation and harmonisation of medical records was designed and implemented in reception centres in three German federal states.

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Objectives: Despite concerns about the impact of the severe acute respiratory syndrome corona virus (SARS-CoV-2) in refugee camps, data on attack rates and effectiveness of containment measures are lacking. We aimed to (1) quantify the attack rate of SARS-CoV-2 during outbreaks in reception and accommodation centres in Germany during the first pandemic wave, (2) assess differences in the attack rate based on containment measures, and (3) provide an overview of testing strategies, communication, conflicts, and protection measures for refugees with special needs.

Methods: Systematic web-based review of outbreak media reports (until June 2020) on confirmed SARS-CoV-2 cases in reception centres for asylum seekers in Germany using the google search engine.

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Membrane traffic in eukaryotic cells is mediated by transport vesicles that bud from a precursor compartment and are transported to their destination compartment where they dock and fuse. To reach their intracellular destination, transport vesicles contain targeting signals such as Rab GTPases and polyphosphoinositides that are recognized by tethering factors in the cytoplasm and that connect the vesicles with their respective destination compartment. The final step, membrane fusion, is mediated by SNARE proteins.

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Synaptic vesicles (SVs) store neurotransmitters and undergo a fine-tuned regulatory and dynamic cycle of exo- and endocytosis, which is essential for neurotransmission at chemical synapses. The development of protocols for isolating SVs from biological extracts was a fundamental accomplishment since it allowed for characterizing the molecular properties of SVs using biochemical methods. In this chapter, we describe a modified procedure for isolating SVs from a few g of rodent brain and that can be completed within ~12 h.

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VIETBIO [Innovative approaches to biodiversity discovery and characterisation in Vietnam] is a bilateral German-Vietnamese research and capacity building project focusing on the development and transfer of new methods and technology towards an integrated biodiversity discovery and monitoring system for Vietnam. Dedicated field training and testing of innovative methodologies were undertaken in Cuc Phuong National Park as part and with support of the project, which led to the new biodiversity data and records made available in this article collection. VIETBIO is a collaboration between the Museum für Naturkunde Berlin - Leibniz Institute for Evolution and Biodiversity Science (MfN), the Botanic Garden and Botanical Museum, Freie Universität Berlin (BGBM) and the Vietnam National Museum of Nature (VNMN), the Institute of Ecology and Biological Resources (IEBR), the Southern Institute of Ecology (SIE), as well as the Institute of Tropical Biology (ITB); all Vietnamese institutions belong to the Vietnam Academy of Science and Technology (VAST).

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