Calcium release through P2X4 activates calmodulin to promote endolysosomal membrane fusion

Intra-endolysosomal Ca(2+) release is required for endolysosomal membrane fusion with intracellular organelles. However, the molecular mechanisms for intra-endolysosomal Ca(2+) release and the downstream Ca(2+) targets involved in the fusion remain elusive. Previously, we demonstrated that endolysosomal P2X4 forms channels activated by luminal adenosine triphosphate in a pH-dependent manner. In this paper, we show that overexpression of P2X4, as well as increasing endolysosomal P2X4 activity by alkalinization of endolysosome lumen, promoted vacuole enlargement in cells and endolysosome fusion in a cell-free assay. These effects were prevented by inhibiting P2X4, expressing a dominant-negative P2X4 mutant, and disrupting the P2X4 gene. We further show that P2X4 and calmodulin (CaM) form a complex at endolysosomal membrane where P2X4 activation recruits CaM to promote fusion and vacuolation in a Ca(2+)-dependent fashion. Moreover, P2X4 activation-triggered fusion and vacuolation were suppressed by inhibiting CaM. Our data thus suggest a new molecular mechanism for endolysosomal membrane fusion involving P2X4-mediated endolysosomal Ca(2+) release and subsequent CaM activation

The two-pore channel TPCN2 mediates NAADP-dependent Ca2+-release from lysosomal stores

Second messenger-induced Ca2+-release from intracellular stores plays a key role in a multitude of physiological processes. In addition to 1,4,5-inositol trisphosphate (IP3), Ca2+, and cyclic ADP ribose (cADPR) that trigger Ca2+-release from the endoplasmatic reticulum (ER), nicotinic acid adenine dinucleotide phosphate (NAADP) has been identified as a cellular metabolite that mediates Ca2+-release from lysosomal stores. While NAADP-induced Ca2+-release has been found in many tissues and cell types, the molecular identity of the channel(s) conferring this release remained elusive so far. Here, we show that TPCN2, a novel member of the two-pore cation channel family, displays the basic properties of native NAADP-dependent Ca2+-release channels. TPCN2 transcripts are widely expressed in the body and encode a lysosomal protein forming homomers. TPCN2 mediates intracellular Ca2+-release after activation with low-nanomolar concentrations of NAADP while it is desensitized by micromolar concentrations of this second messenger and is insensitive to the NAADP analog nicotinamide adenine dinucleotide phosphate (NADP). Furthermore, TPCN2-mediated Ca2+-release is almost completely abolished when the capacity of lysosomes for storing Ca2+ is pharmacologically blocked. By contrast, TPCN2-specific Ca2+-release is unaffected by emptying ER-based Ca2+ stores. In conclusion, these findings indicate that TPCN2 is a major component of the long-sought lysosomal NAADP-dependent Ca2+-release channel

The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI): instrument and pre-launch testing

This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI), to be launched onboard of ESA's Herschel Space Observatory, by 2008. It includes the first results from the instrument level tests. The instrument is designed to be electronically tuneable over a wide and continuous frequency range in the Far Infrared, with velocity resolutions better than 0.1 km/s with a high sensitivity. This will enable detailed investigations of a wide variety of astronomical sources, ranging from solar system objects, star formation regions to nuclei of galaxies. The instrument comprises 5 frequency bands covering 480-1150 GHz with SIS mixers and a sixth dual frequency band, for the 1410-1910 GHz range, with Hot Electron Bolometer Mixers (HEB). The Local Oscillator (LO) subsystem consists of a dedicated Ka-band synthesizer followed by 7 times 2 chains of frequency multipliers, 2 chains for each frequency band. A pair of Auto-Correlators and a pair of Acousto-Optic spectrometers process the two IF signals from the dual-polarization front-ends to provide instantaneous frequency coverage of 4 GHz, with a set of resolutions (140 kHz to 1 MHz), better than < 0.1 km/s. After a successful qualification program, the flight instrument was delivered and entered the testing phase at satellite level. We will also report on the pre-flight test and calibration results together with the expected in-flight performance

Exploration of potentials and strategies of inner urban development and municipal redensification on the example of the city of Krems

Abweichender Titel nach Übersetzung der Verfasserin/des VerfassersDie Stadt Krems ist aufgrund ihrer Lage im Bereich der Wachau, welche UNESCO-Welterbestätte und Landschaftsschutzgebiet ist, in einem landschaftlich sehr heiklen Raum situiert. Zu dessen Schutz sind im regionalen Raumordnungsprogramm NÖ-Mitte auch dementsprechende Siedlungsgrenzen als Schutzmaßnahmen festgelegt. Diese Festlegungen beschränken einerseits die Entwicklung nach außen, da in diesen Gebieten kein neues Bauland mehr gewidmet werden kann, schaffen aber andererseits die Chance, die Themen Innenentwicklung und Nachverdichtung in die Stadtentwicklungsstrategie von Krems aufzunehmen. Damit kann eine nachhaltige Siedlungsentwicklung gewährleistet werden. Durch diese Innenentwicklung und Nachverdichtung kann die derzeitige Flächeninanspruchnahme der beschränkten Ressource Boden, welche durch die Errichtung von Bauwerken und Verkehrswegen entsteht, gebremst und durch die Nutzung von bestehenden Infrastrukturen Kosten gespart werden. Das Ziel dieser Arbeit ist eine Auseinandersetzung mit den Begriffen des Flächenverbrauchs, der Zersiedelung, der Innenentwicklung, der Nachverdichtung, der Nutzungsreserven, der Verdichtungsformen sowie den relevanten Planungsinstrumenten und Maßnahmen. Aufbauend auf diesen theoretischen Grundlagen wird eine Analyse der Stadt Krems aufgrund von Verdichtungsbeispielen für Innenentwicklung und Nachverdichtung in der Stadt durchgeführt, wodurch anschließend Schlüsselräume für Innenentwicklung und Nachverdichtung im Stadtgebiet festgelegt werden können. Schließlich erfolgt die Analyse eines gewählten Schlüsselraumes auf Basis eigener Erhebungen und eine beispielhafte Anwendung verschiedener Verdichtungsformen anhand eines Entwurfs von Baumassen. Somit kann eine gebietsverträgliche Nachverdichtung und deren Potenziale in infrastrukturell gut ausgestatteten Quartieren an einem praktischen Entwurf aufgezeigt werden.Due to its location in the area of the Wachau, which is an UNESCO World Heritage site and landscape conservation area, the city of Krems is located in a very sensitive area. To protect this area the regional spatial planning program of Central Lower Austria set corresponding settlement boundaries. On the one hand these stipulations limit the development beyond the outskirts of the city since no new land can be reclassified into building plots in these areas. On the other hand the restrictions create the opportunity to include inner urban development and municipal redensification into the city development strategy of Krems in order to ensure a sustainable settlement development. This internal development and retroactive densification could slow down the current land consumption of the limited resource soil, created by the construction of buildings and traffic routes, and save costs by using existing infrastructure. It is therefore the objective of this paper to address topics like the concepts of land consumption, urban sprawl, inner urban development, municipal redensification, exploitation of surface reserve, forms of densification, as well as the relevant planning instruments and measures. Based on these theoretical principals an analysis of the city Krems and examples of urban densification will be im-plemented, whereby subsequently key areas for internal development and redensification in the urban area can be defined. Finally, an analysis of a selected key space on the basis of own surveys is carried out followed by an exemplary application of compaction forms using a model of surface areas in order to demonstrate a for a certain area compatible densification and its potential in infrastructural well-appointed quarters by means of a practical design.14

L’arte e ciò che ne resta fuori

Critical discourse on visual arts has dealt with art’s economic implications at least since the Fifties. At the same time, it becomes evident that artworks start to reflect on their relationship with consumer culture. This paper argues how the line is drawn in visual arts and sometimes blurred between art and its outer. In order to corroborate this assumption, the paper analyses the institutional, medial and economic pre-conditions of the field of visual arts. For this purpose, the paper will outline today’s trends in the art market, as well as in the museum and exhibition sector. In conclusion, the paper substantiates the tense relationships between art and consumption on the basis of Claes Oldenburg’s The Store.