Molekulare und genetische Analyse der Furchungskanalbildung während der Zellularisierung in Drosophila melanogaster

Die Embryonalentwicklung in Drosophila beginnt wie die der meisten Insekten mit einer Serie von schnellen syncytialen Zellkernteilungen, den sogenannten Furchungsteilungen, die ohne Zytokinese im embryonalen Zytoplasma stattfinden. Im Ergebnis dieser Teilungen ordnen sich etwa 6000 Zellkerne regelmäßig in einer Schicht direkt unterhalb der embryonalen Plasmamembran an und bilden so das syncytiale Blastoderm. Nach dem Ende der 13. Teilung beginnt in dem etwa einstündigen Prozess der Zellularisierung die Membran an den Stellen zwischen den Zellkernen einem hexagonalen Muster folgend zu invaginieren. Dabei bilden sich zunächst kleine haarnadelförmige Membranschleifen, die sogenannten Furchungskanäle, die dann ins Innere des Embryos wandern. So werden alle peripheren Zellkerne von Membran umschlossen und es entsteht ein einschichtiges polarisiertes Epithelium, das zelluläre Blastoderm. Die Initiation der Zellularisierung nach dem Austritt aus Mitose 13 wird sowohl von zygotischen als auch von maternalen Genen kontrolliert. Dabei spielen insbesondere Faktoren des Zytoskeletts wie f-Aktin und Mikrotubuli sowie endo-und exozytotische Prozesse eine zentrale Rolle. Mit Hilfe von fluoreszenzmarkierten Markerproteinen konnte in dieser Arbeit gezeigt werden, daß die Bildung des Furchungskanals in zwei Phasen abläuft. Zunächst beginnt die Membran nur wenige Minuten nach dem Austritt aus der Telophase von Mitose 13 kleine lokale Einstülpungen zu bilden, die durch die Anreicherung des Transmembranproteins E-cadherin-GFP im Bereich zwischen benachbarten Zellkernen sichtbar werden. In Phase 2 werden schließlich Faktoren wie RhoGEF2 und f-Aktin rekrutiert, die die eingewanderten Membranstrukturen stabilisieren. Dabei wird Phase 1 durch die Aktivität von Komponenten des Recycling Endosoms wie Rab11 und Nuf beeinflußt, während Mutationen in RhoGEF2, dia, nullo, dah und abl eher Phase 2 betreffen. Die Analyse von Doppelmutanten ergab, daß RhoGEF2 und nullo ähnlich wie abl und nullo in jeweils redundanter Weise an der Bildung des Furchungskanals beteiligt sind. Es wird zudem nachgewiesen, daß die Positionen in der Membran, an denen sich Furchungskanäle bilden, vermutlich nicht durch die Lage der mitotischen Pseudocleavagefurchen sondern vielmehr durch eine organisierende Aktivität der Zentrosomen unter Beteiligung der von ihnen ausgehenden Mikrotubuli bestimmt werden. RhoGEF2 ist ein GTP-Austauschfaktor der am Furchungskanal lokalisiert, wo er in Abhängigkeit von Rho1 die Aktivität des Formins Dia und somit die Organisation von f-Aktin kontrolliert. Um die Mechanismen dieser lokalen Rho-Aktivierung besser zu verstehen, wurde die PDZ-Domäne als der Teil des Proteins identifiziert, der die Lokalisation des Proteins vermittelt. So war es möglich physikalische Interaktionspartner zu isolieren, von denen einige auf eine mögliche Rolle bei der Lokalisation von RhoGEF2 untersucht wurden

Occlusion of the infarct-related coronary artery presenting as acute coronary syndrome with and without ST-elevation: impact of inflammation and outcomes in a real-world prospective cohort

Background Patients with ST-segment elevation typically feature total coronary occlusion (TCO) of the infarct-related artery (IRA) on angiography, which may result in worse outcomes. Yet, relying solely on electrocardiogram (ECG) findings may be misleading and those presenting with non-ST-segment elevation acute coronary syndromes (NSTE-ACSs) may have TCO as well. Herein, we aimed to delineate clinical characteristics and outcomes of patients with ACS stratified by IRA location. Methods A total of 4787 ACS patients were prospectively recruited between 2009 and 2017 in SPUM-ACS (ClinicalTrials.gov Identifier: NCT01000701). The primary endpoint was major adverse cardiovascular events (MACEs), a composite of all-cause death, non-fatal myocardial infarction and non-fatal stroke at 1 year. Multivariable-adjusted survival models were fitted using backward selection. Results A total of 4412 ACS patients were included in this analysis, 56.0% (n = 2469) ST-elevation myocardial infarction (STEMI) and 44.0% (n = 1943) NSTE-ACS. The IRA was the right coronary artery (RCA) in 33.9% (n = 1494), the left-anterior descending coronary artery (LAD) in 45.6% (n = 2013), and the left circumflex (LCx) in 20.5% (n = 905) patients. In STEMI patients, TCO (defined as TIMI 0 flow at angiography) was observed in 55% of cases with LAD, in 63% with RCA, and in 55% with LCx. In those presenting with NSTE-ACS, TCO was more frequent in those with LCx and RCA as compared to the LAD (27 and 24%, respectively, vs. 9%, P < 0.001). Among patients with NSTE-ACS, occlusion of the LCx was associated with an increased risk of MACE during 1 year after the index ACS (fully adjusted hazard ratio 1.68, 95% confidence interval 1.10–2.59, P = 0.02; reference: RCA and LAD). Features of patients with NSTE-ACS associated with TCO of the IRA included elevated lymphocyte and neutrophil counts, higher levels of high-sensitivity C reactive protein (hs-CRP) and high-sensitivity cardiac troponin T, lower eGFR, and notably a negative history of MI. Conclusion In NSTE-ACS, both LCx and RCA involvement was associated with TCO at angiography despite the absence of ST-segment elevation. Involvement of the LCx, but not the LAD or RCA, as the IRA represented an independent predictor of MACE during 1-year follow-up. Hs-CRP, lymphocyte, and neutrophil counts were independent predictors of total IRA occlusion, suggesting a possible role of systemic inflammation in the detection of TCO irrespective of ECG presentation

Low-density lipoprotein electronegativity and risk of death after acute coronary syndromes: A case-cohort analysis.

BACKGROUND AND AIMS Low-density lipoprotein (LDL)-cholesterol (LDL-C) promotes atherosclerotic cardiovascular disease (ASCVD), with changes in LDL electronegativity modulating its pro-atherogenic/pro-thrombotic effects. Whether such alterations associate with adverse outcomes in patients with acute coronary syndromes (ACS), a patient population at particularly high cardiovascular risk, remains unknown. METHODS This is a case-cohort study using data from a subset of 2619 ACS patients prospectively recruited at four university hospitals in Switzerland. Isolated LDL was chromatographically separated into LDL particles with increasing electronegativity (L1-L5), with the L1-L5 ratio serving as a proxy of overall LDL electronegativity. Untargeted lipidomics revealed lipid species enriched in L1 (least) vs. L5 (most electronegative subfraction). Patients were followed at 30 days and 1 year. The mortality endpoint was reviewed by an independent clinical endpoint adjudication committee. Multivariable-adjusted hazard ratios (aHR) were calculated using weighted Cox regression models. RESULTS Changes in LDL electronegativity were associated with all-cause mortality at 30 days (aHR, 2.13, 95% CI, 1.07-4.23 per 1 SD increment in L1/L5; p=.03) and 1 year (1.84, 1.03-3.29; p=.04), with a notable association with cardiovascular mortality (2.29; 1.21-4.35; p=.01; and 1.88; 1.08-3.28; p=.03). LDL electronegativity superseded several risk factors for the prediction of 1-year death, including LDL-C, and conferred improved discrimination when added to the updated GRACE score (area under the receiver operating characteristic curve 0.74 vs. 0.79, p=.03). Top 10 lipid species enriched in L1 vs. L5 were: cholesterol ester (CE) (18:2), CE (20:4), free fatty acid (FA) (20:4), phosphatidyl-choline (PC) (36:3), PC (34:2), PC (38:5), PC (36:4), PC (34:1), triacylglycerol (TG) (54:3), and PC (38:6) (all p < .001), with CE (18:2), CE (20:4), PC (36:3), PC (34:2), PC (38:5), PC (36:4), TG (54:3), and PC (38:6) independently associating with fatal events during 1-year of follow-up (all p < .05). CONCLUSIONS Reductions in LDL electronegativity are linked to alterations of the LDL lipidome, associate with all-cause and cardiovascular mortality beyond established risk factors, and represent a novel risk factor for adverse outcomes in patients with ACS. These associations warrant further validation in independent cohorts

Accurate and versatile 3D segmentation of plant tissues at cellular resolution

Quantitative analysis of plant and animal morphogenesis requires accurate segmentation of individual cells in volumetric images of growing organs. In the last years, deep learning has provided robust automated algorithms that approach human performance, with applications to bio-image analysis now starting to emerge. Here, we present PlantSeg, a pipeline for volumetric segmentation of plant tissues into cells. PlantSeg employs a convolutional neural network to predict cell boundaries and graph partitioning to segment cells based on the neural network predictions. PlantSeg was trained on fixed and live plant organs imaged with confocal and light sheet microscopes. PlantSeg delivers accurate results and generalizes well across different tissues, scales, acquisition settings even on non plant samples. We present results of PlantSeg applications in diverse developmental contexts. PlantSeg is free and open-source, with both a command line and a user-friendly graphical interface

Article Developmental Control of Nuclear Size and Shape by kugelkern and kurzkern

Summary Background: The shape of a nucleus depends on the nuclear lamina, which is tightly associated with the inner nuclear membrane and on the interaction with the cytoskeleton. However, the mechanism connecting the differentiation state of a cell to the shape changes of its nucleus are not well understood. We investigated this question in early Drosophila embryos, where the nuclear shape changes from spherical to ellipsoidal together with a 2.5-fold increase in nuclear length during cellularization. Results: We identified two genes, kugelkern and kurzkern, required for nuclear elongation. In kugelkern-and kurzkern-depleted embryos, the nuclei reach only hal

Digital sequence information is changing the way genetic resources are used in agricultural research and development: implications for new benefit-sharing norms

This paper analyses the ways in which CGIAR Centers use digital sequence information (DSI) in their efforts to conserve and sustainably utilize the world’s most important crop and livestock genetic diversity. The paper then reflects on which of the benefit-sharing options currently under consideration by the Contracting Parties to the CBD (and the versions of those options that must be considered by the Governing Body of the Plant Treaty and the UN FAO Commission on Genetic Resources for Food and Agriculture) would provide effective policy support for the continued use of DSI in agricultural research and development in the future

A compressed sensing feature extraction approach for diagnostics and prognostics in electromagnetic solenoids

One major realm of Condition Based Maintenance is finding features that reflect the current health state of the asset or component under observation. Most of the existing approaches are accompanied with high computational costs during the different feature processing phases making them infeasible in a real-world scenario. In this paper a feature generation method is evaluated compensating for two problems: (1) storing and handling large amounts of data and (2) computational complexity. Both aforementioned problems are existent e.g. when electromagnetic solenoids are artificially aged and health indicators have to be extracted or when multiple identical solenoids have to be monitored. To overcome those problems, Compressed Sensing (CS), a new research field that keeps constantly emerging into new applications, is employed. CS is a data compression technique allowing original signal reconstruction with far fewer samples than Shannon-Nyquist dictates, when some criteria are met. By applying this method to measured solenoid coil current, raw data vectors can be reduced to a way smaller set of samples that yet contain enough information for proper reconstruction. The obtained CS vector is also assumed to contain enough relevant information about solenoid degradation and faults, allowing CS samples to be used as input to fault detection or remaining useful life estimation routines. The paper gives some results demonstrating compression and reconstruction of coil current measurements and outlines the application of CS samples as condition monitoring data by determining deterioration and fault related features. Nevertheless, some unresolved issues regarding information loss during the compression stage, the design of the compression method itself and its influence on diagnostic/prognostic methods exist

Adaptive position-dependent friction characteristics for electromagnetic actuators

An approach for an adaptive position-dependent friction estimation for linear electromagnetic actuators with altered characteristics is proposed in this paper. The objective is to obtain a friction model that can be used to describe different stages of aging of magnetic actuators. It is compared to a classical Stribeck friction model by means of model fit, sensitivity, and parameter correlation. The identifiability of the parameters in the friction model is of special interest since the model is supposed to be used for diagnostic and prognostic purposes. A method based on the Fisher information matrix is employed to analyze the quality of the model structure and the parameter estimates