Detection of the high energy component of Jovian electrons in Low Earth Orbit with the PAMELA experiment

The PAMELA experiment is devoted to the study of cosmic rays in Low Earth Orbit with an apparatus optimized to perform a precise determination of the galactic antimatter component of c.r. It is constituted by a number of detectors built around a permanent magnet spectrometer. PAMELA was launched in space on June 15th 2006 on board the Russian Resurs-DK1 satellite for a mission duration of three years. The characteristics of the detectors, the long lifetime and the orbit of the satellite, will allow to address several aspects of cosmic-ray physics. In this work we discuss the observational capabilities of PAMELA to detect the electron component above 50 MeV. The magnetic spectrometer allows a detailed measurement of the energy spectrum of electrons of galactic and Jovian origin. Long term measurements and correlations with Earth-Jupiter 13 months synodic period will allow to separate these two contributions and to measure the primary electron Jovian component, dominant in the 50-70 MeV energy range. With this technique it will also be possible to study the contribution to the electron spectrum of Jovian e- reaccelerated up to 2 GeV at the Solar Wind Termination Shock.Comment: On behalf of PAMELA collaboration. Accepted for publication on Advances in Space Researc

Structure of the Shroom-Rho Kinase Complex Reveals a Binding Interface with Monomeric Shroom That Regulates Cell Morphology and Stimulates Kinase Activity

Shroom-mediated remodeling of the actomyosin cytoskeleton is a critical driver of cellular shape and tissue morphology that underlies the development of many tissues including the neural tube, eye, intestines, and vasculature. Shroom uses a conserved SD2 domain to direct the subcellular localization of Rho-associated kinase (Rock), which in turn drives changes in the cytoskeleton and cellular morphology through its ability to phosphorylate and activate non-muscle myosin II. Here, we present the structure of the human Shroom-Rock binding module, revealing an unexpected stoichiometry for Shroom in which two Shroom SD2 domains bind independent surfaces on Rock. Mutation of interfacial residues impaired Shroom-Rock binding in vitro and resulted in altered remodeling of the cytoskeleton and loss of Shroom-mediated changes in cellular morphology. Additionally, we provide the first direct evidence that Shroom can function as a Rock activator. These data provide molecular insight into the Shroom-Rock interface and demonstrate that Shroom directly participates in regulating cytoskeletal dynamics, adding to its known role in Rock localization

Ascorbate-mediated regulation of growth, photoprotection, and photoinhibition in Arabidopsis thaliana.

The requirements for ascorbate for growth and photosynthesis were assessed under low (LL; 250 µmol m-2 s-1) or high (HL; 1600 µmol m-2 s-1) irradiance in wild-type Arabidopsis thaliana and two ascorbate synthesis mutants (vtc2-1 and vtc2-4) that have 30% wild-type ascorbate levels. The low ascorbate mutants had the same numbers of leaves but lower rosette area and biomass than the wild type under LL. Wild-type plants experiencing HL had higher leaf ascorbate, anthocyanin, and xanthophyll pigments than under LL. In contrast, leaf ascorbate levels were not increased under HL in the mutant lines. While the degree of oxidation measured using an in vivo redox reporter in the nuclei and cytosol of the leaf epidermal and stomatal cells was similar under both irradiances in all lines, anthocyanin levels were significantly lower in the low ascorbate mutants than in the wild type under HL. Differences in the photosynthetic responses of vtc2-1 and vtc2-4 mutants were observed. Unlike vtc2-1, the vtc2-4 mutants had wild-type zeaxanthin contents. While both low ascorbate mutants had lower levels of non-photochemical quenching of chlorophyll a fluorescence (NPQ) than the wild type under HL, qPd values were greater only in vtc2-1 leaves. Ascorbate is therefore essential for growth but not for photoprotection

Structure of a highly conserved domain of rock1 required for shroom-mediated regulation of cell morphology

Rho-associated coiled coil containing protein kinase (Rho-kinase or Rock) is a well-defined determinant of actin organization and dynamics in most animal cells characterized to date. One of the primary effectors of Rock is non-muscle myosin II. Activation of Rock results in increased contractility of myosin II and subsequent changes in actin architecture and cell morphology. The regulation of Rock is thought to occur via autoinhibition of the kinase domain via intramolecular interactions between the N-terminus and the C-terminus of the kinase. This autoinhibited state can be relieved via proteolytic cleavage, binding of lipids to a Pleckstrin Homology domain near the C-terminus, or binding of GTP-bound RhoA to the central coiled-coil region of Rock. Recent work has identified the Shroom family of proteins as an additional regulator of Rock either at the level of cellular distribution or catalytic activity or both. The Shroom-Rock complex is conserved in most animals and is essential for the formation of the neural tube, eye, and gut in vertebrates. To address the mechanism by which Shroom and Rock interact, we have solved the structure of the coiled-coil region of Rock that binds to Shroom proteins. Consistent with other observations, the Shroom binding domain is a parallel coiled-coil dimer. Using biochemical approaches, we have identified a large patch of residues that contribute to Shrm binding. Their orientation suggests that there may be two independent Shrm binding sites on opposing faces of the coiled-coil region of Rock. Finally, we show that the binding surface is essential for Rock colocalization with Shroom and for Shroom-mediated changes in cell morphology. © 2013 Mohan et al

Review of solar energetic particle models

Solar Energetic Particle (SEP) events are interesting from a scientific perspective as they are the product of a broad set of physical processes from the corona out through the extent of the heliosphere, and provide insight into processes of particle acceleration and transport that are widely applicable in astrophysics. From the operations perspective, SEP events pose a radiation hazard for aviation, electronics in space, and human space exploration, in particular for missions outside of the Earth’s protective magnetosphere including to the Moon and Mars. Thus, it is critical to improve the scientific understanding of SEP events and use this understanding to develop and improve SEP forecasting capabilities to support operations. Many SEP models exist or are in development using a wide variety of approaches and with differing goals. These include computationally intensive physics-based models, fast and light empirical models, machine learning-based models, and mixed-model approaches. The aim of this paper is to summarize all of the SEP models currently developed in the scientific community, including a description of model approach, inputs and outputs, free parameters, and any published validations or comparisons with data.</p

Molecular aspects of RNA-recognition by the neuronal mRNA transport factor Staufen 2

Staufen (Stau) is a double-stranded RNA-binding protein (dsRBP) originally identified as an mRNA transport factor and germ-cell marker in Drosophila. The mammalian homolog Staufen 2 (Stau2) is specifically expressed in neurons, where it clusters in RNA granules and moves along microtubules from cell bodies to dendrites. Stau2 is an important core factor for neuronal mRNA transport and has been implicated in synaptic plasticity, memory and learning. Stau2 knockdown in rats results in reduced numbers of mature dendritic spines and impairs long-term depression of synapses. All Stau proteins contain four to five dsRNA-binding domains (RBDs). For all Stau proteins RBD3 and RBD4 are thought to be the only active RNA-binding domains, whereas RBDs 1, 2 and 5 are considered to be pseusoRBDs, which retained the fold but no activity for RNA binding. To date, the mechanistic basis of Stau2 function in the cell is not well understood. The translational repressor Pumilio 2 (Pum2) acts in the same pathways as Stau2 by forming joint messenger ribonucleoproteins (mRNPs). The 3’ untranslated region (UTR) of the Stau2 target mRNA Regulator of G-protein signaling 4 (Rgs4) comprises two predicted Staufen-recognized structures (SRSs) and two Pum2 binding sites in close proximity, suggesting a functional complex of Stau2, Pum2 and Rgs4. In this work, it could be confirmed that Stau2 and Pum2 both bind to the Rgs4 3’UTR. However, a functional complex of Stau2 and Pum2 with Rgs4 that could mediate their role in common biological processes could not be confirmed. This work shows that in Stau2 also the non-canonical RBDs 1 and 2 exhibit RNA-binding activity. Their RNA-binding activity was characterized by biochemical and biophysical methods and an important role for both domains in RNA-recognition is demonstrated. Although RBDs 3 and 4 alone achieve high affinity binding, RBDs 1 and 2 are required to form stable complexes with RNA. This feature might be of great importance for biological target recognition and the transport of RNAs over longer distances

Korruption – Einstellung – Polizei

In diesem Beitrag werden die Ergebnisse einer Personalbefragung österreichischer Polizisten und Polizistinnen in Ausbildung geschildert, bei denen die Einstellung zu Korruption erhoben wurde. Weiterhin wurden Variablen wie Geschlecht, Alter und Bildungsgrad erhoben, die in Hellfeldforschung zu Korruption häufig als Merkmale von Korruptionstätern und Korruptionstäterinnen genannt werden. Im Fokus dieses Beitrags steht unter anderem die Frage, inwieweit sich Befunde aus dem Hellfeld von Korruption im Dunkelfeld abbilden. Zur Klärung dieser Frage werden Merkmale aus dem Hellfeld der Korruptionstäter und Korruptionstäterinnen auf eine Ursache-Wirkungs-Beziehung mit der Einstellung zu Korruption im Dunkelfeld überprüft. Zudem wird in diesem Beitrag die Frage geklärt, wie die Polizisten und Polizistinnen in Ausbildung hinsichtlich der Einstellung zu Korruption im Vergleich mit der Allgemeinbevölkerung Österreichs abschneiden. Polizisten und Polizistinnen in Ausbildung sind für das Bundesamt zur Korruptionsprävention und Korruptionsbekämpfung (kurz: BAK) die größte Zielgruppe bei der Ausbildung und Weiterbildung öffentlich Bediensteter in Österreich. Die Ergebnisse lassen erkennen, dass sich die Befunde aus dem Hellfeld von Korruption nicht im Dunkelfeld abbilden, denn die überprüften Variablen weisen insgesamt betrachtet keine substanzielle Ursache-Wirkungs-Beziehung mit der Einstellung zu Korruption auf. Hinsichtlich des Vergleichs der österreichischen Polizisten und Polizistinnen in Ausbildung mit der Allgemeinbevölkerung Österreichs zeigen sich nur geringfügige Unterschiede in der Einstellung zu Korruption. Tendenziell lehnen die Polizisten und Polizistinnen in Ausbildung Korruption eher ab als die Allgemeinbevölkerung Österreichs

Tropomyosin 1-I/C coordinates kinesin-1 and dynein motors during oskar mRNA transport.

Acknowledgements: We thank L. Dimitrova-Paternoga (European Molecular Biology Laboratory (EMBL) Heidelberg) for reagents, the EMBL Protein Expression and Purification Core Facility, the EMBL Advanced Light Microscopy Facility, especially M. Lampe, and the EMBL Chemical Biology Core Facility, especially D. Will, for their support. We thank the Bio-SAXS beamline at European Synchrotron Radiation Facility (ESRF) Grenoble, BM29. We thank P. Pernot (ESRF), J. Kieffer (ESRF) and C. Jeffries (EMBL Hamburg) for discussions. S.H. was supported by the EMBL Interdisciplinary Postdoctoral fellowship (EIPOD) Programme under Marie Curie Cofund Actions MSCA-COFUND-FP (grant no. 664726) and Deutsche Forschungsgemeinschaft (DFG)-Forschergruppe 2333 grant (grant no. EP37/4-1) to A.E. The graphics in Fig. 7 were generated by E. Chiang as part of the MRC Laboratory of Molecular Biology’s VisLab, and adapted for use in Fig. 1b. Work in the laboratories of J.H. and A.E. was supported by funding from the DFG via the priority program SPP1935 to J.H. and A.E. (grant nos EP37/3-1 and EP37/3-2) and the EMBL. Work in S.L.B.’s group is supported by the Medical Research Council (MRC), as part of United Kingdom Research and Innovation (also known as UK Research and Innovation; MRC file reference no. MC_U105178790). M.A.M. is supported by a project grant from the Biotechnology and Biological Sciences Research Council (grant no. BB/T00696X/1) awarded to S.L.B. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. For the purpose of the MRC open access policy, the authors have applied a CC-BY public copyright license to any Author Accepted Manuscript version arising.Dynein and kinesin motors mediate long-range intracellular transport, translocating towards microtubule minus and plus ends, respectively. Cargoes often undergo bidirectional transport by binding to both motors simultaneously. However, it is not known how motor activities are coordinated in such circumstances. In the Drosophila female germline, sequential activities of the dynein-dynactin-BicD-Egalitarian (DDBE) complex and of kinesin-1 deliver oskar messenger RNA from nurse cells to the oocyte, and within the oocyte to the posterior pole. We show through in vitro reconstitution that Tm1-I/C, a tropomyosin-1 isoform, links kinesin-1 in a strongly inhibited state to DDBE-associated oskar mRNA. Nuclear magnetic resonance spectroscopy, small-angle X-ray scattering and structural modeling indicate that Tm1-I/C suppresses kinesin-1 activity by stabilizing its autoinhibited conformation, thus preventing competition with dynein until kinesin-1 is activated in the oocyte. Our work reveals a new strategy for ensuring sequential activity of microtubule motors