The Arabidopsis elch mutant reveals functions of an ESCRT component in cytokinesis

The Endosomal Sorting Complex Required for Transport (ESCRT) regulates important functions in the secretory system of yeast and animals. The main responsibilities that have been described so far are sorting of biosynthetic cargo and receptor-downregulation. The scope of my PhD thesis was the analysis of the Arabidopsis ELCH protein that is similar to Vps23p and TSG101. These proteins represent the core components of ESCRT I complex in yeast and animals. I could show that ubiquitin binding and complex formation is conserved between Arabidopsis, yeast and animals, supporting the idea that ESCRT mediated protein sorting is a general strategy in eukaryotic organisms. New ELCH/ESCRT-I interacting proteins were isolated by immunoprecipitation and subsequent mass spectrometry. By this approach a plant specific protein containing a UBiquitin Associated (UBA) domain and several subunits of the vacuolar (H+)-ATPase were identified. The VHA-a3 subunit of the vacuolar (H+)-ATPase was analysed in more detail for ubiquitin modifications because mono-ubiquitination constitutes the sorting signal for the ESCRT pathway. Two colour western analysis showed that VHA-a3 is mono-ubiquitinated indicating that VHA-a3 might be a target of ELCH/ESCRT-I. Similar to the ESCRT pathway the V-ATPase is involved in the sorting of biosynthetic cargo and receptor-downregulation in yeast. No interaction between the ESCRT pathway and the V-ATPase has been reported so far. A T-DNA mutation in the ELCH gene of Arabidopsis results in multiple nuclei in a minority of epidermal cells. As multinucleated cells can be an indication for a cell division defect, trichomes, pavement cells and stomata were examined in respect to incomplete cell walls. Cell wall stubs were observed in pavement cells and stomata but not in trichomes. Similar defects have not been observed in yeast vps23 but the multinucleated phenotype of elch resembles the phenotype observed in TSG101 mutant cell lines. Furthermore cytokinesis defects are reported in Arabidopsis mutants lacking the VHA-E subunit of the V-ATPase. Plants mutant for VHA-E are embryonic lethal and display incomplete cell walls, multiple nuclei and aberrant vacuoles (Strompen et al., 2005). Although mutations in ELCH, TSG101 and VHA-E cause a similar phenotype only vague ideas exist why compromising the ESCRT pathway or the V-ATPase lead to cell division defects. A cue was provided by genetic analysis, which suggests that ELCH influences cell division by regulating microtubules. This is apparent because a double mutant with tubulin-folding cofactor a (tfc-a) shows a strong synergistic phenotype. Cell wall development during plant cell division depends heavily on a plant specific structure, the phragmoplast. The secretory system and microtubules are the main components of the phragmoplast. Therefore it seems reasonable to assume that subtle protein sorting defects, mislocalization of membranes or misregulation of microtubules can lead to the observed cell division defect

Modification of titanium implants surface by microarc oxidation in presence of polymeric solutions. The study of immune response

In the present study, we performed the in vitro evaluation of titanium samples with four types of coatings obtained by microarc oxidation (MAO): pure calcium phosphate (CaP), CaP- chitosan, CaP- hyaluronic acid, CaP - polyvinylpyrrolidone coatings. AlamarBlue test and TNFα secretion analysis (ELISA) were performed to investigate the immune response. It was shown that formation of MAO hybrid calciumphosphate coatings increases the biocompatibility of samples. Adding of polyvinylpyrrolidone and hyaluronic acid to the electrolyte solution presumably makes it possible to obtain hybrid coatings with anti-inflammatory properties

Terrestrial planet formation from lost inner solar system material

Two fundamentally different processes of rocky planet formation exist, but it is unclear which one built the terrestrial planets of the solar system. They formed either by collisions among planetary embryos from the inner solar system or by accreting sunward-drifting millimeter-sized “pebbles” from the outer solar system. We show that the isotopic compositions of Earth and Mars are governed by two-component mixing among inner solar system materials, including material from the innermost disk unsampled by meteorites, whereas the contribution of outer solar system material is limited to a few percent by mass. This refutes a pebble accretion origin of the terrestrial planets but is consistent with collisional growth from inner solar system embryos. The low fraction of outer solar system material in Earth and Mars indicates the presence of a persistent dust-drift barrier in the disk, highlighting the specific pathway of rocky planet formation in the solar system

Short term outcome after left atrial appendage occlusion with the AMPLATZER Amulet and WATCHMAN device: results from the ORIGINAL registry (saxOnian RegIstry analyzinG and followINg left atrial Appendage cLosure)

Background: Various randomized multicenter studies have shown that percutaneous left atrial appendage closure (LAAC) is not inferior in stroke prevention compared to vitamin K antagonists (VKA) and can be performed safely and effectively. Aims: The prospective multicenter ORIGINAL registry in the Free State of Saxony (saxOnian RegIstry analyzinG and followINg left atrial Appendage cLosure) investigated the efficiency and safety of LAAC with Watchman or Amulet device in a real word setting. A special focus was put on the influence of LAAC frequency on periprocedural efficiency and safety. Methods and results: The total of 482 consecutive patients (Abbott Amulet N = 93 and Boston Scientific Watchman N = 389) were included in the periinterventional analyses. After 6 weeks, 353 patients completed the first follow-up including transoesophageal echocardiography (TEE) (73.2%). Successful LAAC could be performed in more than 94%. The complication rate does not significantly differ between device types (p = 0.92) according to Fischer test and comprised 2.2% in the Amulet and 2.3% in the Watchman group. The kind of device and the frequency of LAAC per study center had no influence on the success and complication rates. Device related thrombus could be revealed more frequently in the Watchman group (4.5%) than in the Amulet group (1.4%) but this difference is still not significant in Fisher test (p = 0.14). Same conclusion can be made about residual leakage 1.1% versus 0% [not significant in Fisher test (p = 0.26)]. Dual antiplatelet therapy followed the intervention in 64% and 22% of patients were discharged under a combination of an anticoagulant (VKA/DOAC/Heparin) and one antiplatelet agent. Conclusions: The ORIGINAL registry supports the thesis from large, randomized trials that LAAC can be performed with a very high procedural success rate in the everyday clinical routine irrespective of the used LAA device (Watchman or Amulet). The postprocedural antithrombotic strategy differs widely among the participating centers

Effiziente und Robuste Entwicklung komplexer Faserverbund-Triebwerkstrukturen

Steigende Anforderungen an die Leistungsfähigkeit und Effizienz von Triebwerken lassen sich durch den Einsatz von Metall-Faserverbund-Bauweisen erfüllen. Faser-Kunststoff-Verbunde (FKV) mit ihren herausragenden und einstellbaren mechanischen Eigenschaften bieten das Potential, die Masse strukturell hochbelasteter Komponenten zu reduzieren. Durch die richtungsabhängigen Eigenschaften kann der FKV zielgerichtet für die Anwendung angepasst werden. Die Vielzahl der einstellbaren Parameter in Kombination mit der Entwicklung von komplexen Triebwerkstrukturen führt zu einem interaktiven und interagierenden Entwicklungsprozess. Im Rahmen dieses Beitrages wird ein Ansatz zur kombiniert virtuell-reellen Entwicklung eines Triebwerk-Subsystems am Beispiel des Zwischengehäuses vorgestellt. Ein systematischer Prozess in Kombination mit virtuellen Methoden ermöglicht die effiziente Erarbeitung und modellhafte Abbildung des Gesamtsystems, bestehend aus relevanten Triebwerkselementen (System), dem darin integrierten Zwischengehäuse (Subsystem) und lastübertragenden Faserverbund-Leitschaufeln (Komponente). Durch Detaillierung im Entwicklungsprozess steigt kontinuierlich die Aussagegenauigkeit, wobei gleichzeitig auch der Aufwand erheblich zunimmt. Ein experimenteller Funktions- und Festigkeitsnachweis der Leitschaufel kann zur Reduktion des Entwicklungsrisikos beitragen. Die dafür benötigten Funktionsmuster lassen sich in einem kombinierten Verfahren, bestehend aus Additiver Fertigung und Resin Transfer Moulding, herstellen, wobei der 3D-Druck die Anpassung der realen Funktionsmuster an die Geometrie- und Werkstoffmodifikationen im Rahmen der virtuellen Entwicklung ermöglicht

Regulation of stearoyl-CoA desaturase-1 after central and peripheral nerve lesions

BACKGROUND: Interruption of mature axons activates a cascade of events in neuronal cell bodies which leads to various outcomes from functional regeneration in the PNS to the failure of any significant regeneration in the CNS. One factor which seems to play an important role in the molecular programs after axotomy is the stearoyl Coenzyme A-desaturase-1 (SCD-1). This enzyme is needed for the conversion of stearate into oleate. Beside its role in membrane synthesis, oleate could act as a neurotrophic factor, involved in signal transduction pathways via activation of protein kinases C. RESULTS: In situ hybridization and immunohistochemistry demonstrated a strong up-regulation of SCD at mRNA and protein level in regenerating neurons of the rat facial nucleus whereas non-regenerating Clarke's and Red nucleus neurons did not show an induction of this gene. CONCLUSION: This differential expression points to a functionally significant role for the SCD-1 in the process of regeneration

Low rate of asymptomatic cerebral embolism and improved procedural efficiency with the novel pulmonary vein ablation catheter GOLD: results of the PRECISION GOLD trial

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