A model for the self-organization of vesicular flux and protein distributions in the Golgi apparatus

The generation of two non-identical membrane compartments via exchange of vesicles is considered to require two types of vesicles specified by distinct cytosolic coats that selectively recruit cargo and two membrane-bound SNARE pairs that specify fusion and differ in their affinities for each type of vesicles. The mammalian Golgi complex is composed of 6-8 non-identical cisternae that undergo gradual maturation and replacement yet features only two SNARE pairs. We present a model that explains how the distinct composition of Golgi cisternae can be generated with two and even a single SNARE pair and one vesicle coat. A decay of active SNARE concentration in aging cisternae provides the seed for a cis > trans SNARE gradient that generates the predominantly retrograde vesicle flux which further enhances the gradient. This flux in turn yields the observed inhomogeneous steady-state distribution of Golgi enzymes, which compete with each other and with the SNAREs for incorporation into transport vesicles. We show analytically that the steady state SNARE concentration decays exponentially with the cisterna number. Numerical solutions of rate equations reproduce the experimentally observed SNARE gradients, overlapping enzyme peaks in cis, medial and trans and the reported change in vesicle nature across Golgi: Vesicles originating from younger cisternae mostly contain Golgi enzymes and SNAREs enriched in these cisternae and extensively recycle through the Endoplasmic Reticulum (ER), while the other subpopulation of vesicles contains Golgi proteins prevalent in older cisternae and hardly reaches the ER.Comment: 15 pages, 6 figure

Proton Pump Inhibitors Exert Anti-Allergic Effects by Reducing TCTP Secretion

BACKGROUND:Extracellular translationally controlled tumor protein (TCTP) is known to play a role in human allergic responses. TCTP has been identified outside of macrophages, in activated mononuclear cells, and in biological fluids from allergic patients. Even TCTP devoid of signal sequences, is secreted to extracellular environment by an yet undefined mechanism. This study is aimed at understanding the mechanism of TCTP release and its regulation. A secondary goal is to see if inhibitors of TCTP release can serve as potential anti-allergic asthmatic drugs. METHODOLOGY/PRINCIPAL FINDINGS:Using Western blotting assay in HEK293 and U937 cells, we found that TCTP secretion is reduced by omeprazole and pantoprazole, both of which are proton pump inhibitors. We then transfected HEK293 cells with proton pump expression vectors to search for the effects of exogeneously overexpressed H(+)/K(+)-ATPase on the TCTP secretion. Based on these in vitro data we checked the in vivo effects of pantoprazole in a murine model of ovalbumin-induced allergy. Omeprazole and pantoprazole reduced TCTP secretion from HEK293 and U937 cells in a concentration-dependent fashion and the secretion of TCTP from HEK293 cells increased when they over-expressed H(+)/K(+)-ATPase. In a murine model of ovalbumin-induced allergy, pretreatment with pantoprazole reduced infiltration of inflammatory cells, increased goblet cells, and increased TCTP secretion induced by OVA challenge. CONCLUSION:Since Omeprazole and pantoprazole decrease the secretion of TCTP which is associated with the development of allergic reaction, they may have the potential to serve as anti-allergic (asthmatic) drugs

Tsetse GmmSRPN10 has anti-complement activity and is important for successful establishment of trypanosome infections in the fly midgut

The complement cascade in mammalian blood can damage the alimentary tract of haematophagous arthropods. As such, these animals have evolved their own repertoire of complement-inactivating factors, which are inadvertently exploited by blood-borne pathogens to escape complement lysis. Unlike the bloodstream stages, the procyclic (insect) stage of Trypanosoma brucei is highly susceptible to complement killing, which is puzzling considering that a tsetse takes a bloodmeal every 2–4 days. In this study, we identified four tsetse (Glossina morsitans morsitans) serine protease inhibitors (serpins) from a midgut expressed sequence tag (EST) library (GmmSRPN3, GmmSRPN5, GmmSRPN9 and GmmSRPN10) and investigated their role in modulating the establishment of a T. brucei infection in the midgut. Although not having evolved in a common blood-feeding ancestor, all four serpins have an active site sharing remarkable homology with the human complement C1-inhibitor serpin, SerpinG1. RNAi knockdown of individual GmmSRPN9 and GmmSRPN10 genes resulted in a significant decreased rate of infection by procyclic form T. brucei. Furthermore, recombinant GmmSRPN10 was both able to inhibit the activity of human complement-cascade serine proteases, C1s and Factor D, and to protect the in vitro killing of procyclic trypanosomes when incubated with complement-activated human serum. Thus, the secretion of serpins, which may be part of a bloodmeal complement inactivation system in tsetse, is used by procyclic trypanosomes to evade an influx of fresh trypanolytic complement with each bloodmeal. This highlights another facet of the complicated relationship between T. brucei and its tsetse vector, where the parasite takes advantage of tsetse physiology to further its chances of propagation and transmission

Untersuchungen zum Nachweis von Uebergangsstrahlung fuer die e/pi-Trennung im ZEUS-Experiment

SIGLEAvailable from Bonn Univ. (DE). Physikalisches Inst. / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Entwicklung und Bau des ZEUS-Uebergangsstrahlungsdetektors

For the ZEUS experiment a transition radiation detector (TRD) has been constructed and comissioned in order to improve the recognition of electron tracks within hadronic jets be detecting transition radiation of electrons. The TRD consists of four independent modules. Each module contains of a radiator for creation and a longitudinal drift chamber for detection of transition radiation. The radiator consists of polypropylene fibres woven into a fleece. Its overal thickness is about 70 mm. The wire chambers have a depth of 22 mm and are filled mainly with xenon (90%). Drift chamber and radiator are integrated into the TRD modules which are constructed of glass- reinforced plastic only. This material is rigid enough to endure the stress of wire tensions and its radiation length is small. The readout electronics is optimized for a detailed signal-structure analysis ('cluster counting method'). It is composed of preamplifier, postamplifier with pulse-shaping and flash analog-to-digital converters (FADCs) to amplify, shape and digitize anode and cathode signals. A method for cross-calibration of the readout channels was tested by using uranium radiation of the ZEUS calorimeter. (orig.)Im Rahmen dieser Arbeit wurde fuer das ZEUS-Experiment ein Uebergangsstrahlungsdetektor konstruiert und gebaut. Er dient vorwiegend dem Elektronennachweis bei semileptonischen Zerfaellen schwerer Quarks in der Vorwaertsrichtung des ZEUS-Experimentes. Der Detektor besteht auf aus vier unabhaengigen Modulen, die im Vorwaertsbereich des ZEUS-Spektrometers zwischen den planaren Driftkammern des FTD angebracht sind. Die Uebergangsstrahlung wird in einem Radiator aus Polypropylen Vliesmatten erzeugt. Die selbstragende Radiatorstruktur ermoeglichte die Integration in die TRD-Module. Die Kammersignalverstaerker wurden in Zusammenarbeit mit einer Arbeitsgruppe der Universitaet Siegen entwickelt. Es werden sowohl die Anoden, als auch die senkrecht dazu orientierten Kathoden ausgelesen. Hochverstaerkende Driftkammerelektronik ermoeglicht den Betrieb der Nachweiskammer bei niedrigen Gasverstaerkungen und damit hoher Energieaufloesung. Die Kammersignale werden mit FADCs digitalisiert. Es wurden die verschiedenen Methoden einer Kanal-zu-Kanal-Kalibrierung aufgezeigt. Speziell wurde die Nutzung der Restradioaktivitaet der Kalorimetermodule (Uran-Rauschen) zur Kalibration getestet. (orig./HSI)SIGLEAvailable from TIB Hannover: RN 4852(93-18) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Analysis of the Characteristics and Content of Twitch Live-streaming

YouTube is the most popular community-driven video streaming Website, and thus has been the subject of many studies. Similarly, Twitch is the most popular community driven live-streaming Website, broadcasting gaming content live to millions of people. Despite their similarities, less is known about Twitch's streaming and content characteristics. This project gathers data on Twitch through three tools: A Web crawler, a survey, and a third-party Website. Analysis of the results shows the following: Game popularity changes unpredictably over time, as age increases, the number of people that use Twitch decreases, and there are only two commonly used resolutions between most popular and least popular channels. The results should aid in the development of future live-streaming platforms

Endicia Webtools Optimization and Migration

This project worked with Endicia to bring an external United States Postal Service system into Endicia’s environment. The system is used to calculate data needed to print shipping labels for packages. We built a full-stack server-to- database application that interfaces with Endicia’s services. We received requirements to prioritize performance and to handle hundreds of requests per second while never incurring downtime. Through this project, we made this service’s response times 30x faster. The program was then handed off for deployment