2,316 research outputs found
Wikipedia’s open content production platform createssignificant spillover benefits that encourage users to contributefurther
No full textMany organisations are developing open platforms to create, store and share knowledge. Aleksi Aaltonen and Stephan Seiler analyse editing data by Wikipedia users to show how content creation by individuals generates significant ‘spillover’ benefits, encouraging others to contribute to the collective process of knowledge production
How taking a bit longer to do your shopping might save you money
No full textTo what extent can shoppers convert the time they spend looking for particular products into monetary savings? Using electronic tags to study the behavior of 12,000 consumers in a large supermarket in Northern California, Fabio Pinna and Stephan Seiler find that consumers can save up to $11 per shopping trip just by searching longer for products
Tales of RAM and MOR: NDR kinase signaling in fungal morphogenesis
No full textNDR kinases are crucial for growth, differentiation, and pathogenicity in all analyzed fungal species. They require association with MOB co-activators and several scaffolding proteins for their function. Phosphorylation of two conserved residues in the activation segment and the hydrophobic motif controls the transition between an enzymatic inactive, basal active, and fully active state of the NDR kinase. Although cellular functions of NDR kinases are only beginning to emerge, regulation of small G-proteins of the Rho and Rab families and combinatorial transcriptional and translational regulation of gene expression are conserved signaling patterns among fungal and higher eukaryotic NDR kinase pathways.Deutsche Forschungsgemeinschaf
The RHO1-specific GTPase-activating Protein LRG1 Regulates Polar Tip Growth in Parallel to Ndr Kinase Signaling in Neurospora
No full textRegulation of Rho GTPase signaling is critical for cell shape determination and polarity. Here, we investigated the role of LRG1, a novel member of the GTPase-activating proteins ( GAPs) of Neurospora crassa. LRG1 is essential for apical tip extension and to restrict excessive branch formation in subapical regions of the hypha and is involved in determining the size of the hyphal compartments. LRG1 localizes to hyphal tips and sites of septation via its three LIM domains. The accumulation of LRG1 as an apical cap is dependent on a functional actin cytoskeleton and active growth, and is influenced by the opposing microtubule-dependent motor proteins dynein and kinesin-1. Genetic evidence and in vitro GTPase assays identify LRG1 as a RHO1-specific GAP affecting several output pathways of RHO1, based on hyposensitivity to the glucan inhibitor caspofungin, synthetic lethality with a hyperactive beta 1,3-glucan synthase mutant, altered PKC/MAK1 pathway activities, and hypersensitivity to latrunculin A. The morphological defects of lrg-1 are highly reminiscent to the Ndr kinase/RAM pathway mutants cot-1 and pod-6, and genetic evidence suggests that RHO1/LRG1 function in parallel with COT1 in coordinating apical tip growth
Conserved components, but distinct mechanisms for the placement and assembly of the cell division machinery in unicellular and filamentous ascomycetes
No full textP>Cytokinesis is essential for cell proliferation, yet its molecular description is challenging, because > 100 conserved proteins must be spatially and temporally co-ordinated. Despite the high importance of a tight co-ordination of cytokinesis with chromosome and organelle segregation, the mechanism for determining the cell division plane is one of the least conserved aspects of cytokinesis in eukaryotic cells. Budding and fission yeast have developed fundamentally distinct mechanisms to ensure proper nuclear segregation. The extent to which these pathways are conserved in multicellular fungi remains unknown. Recent progress indicates common components, but different mechanisms that are required for proper selection of the septation site in the different groups of Ascomycota. Cortical cues are used in yeast- and filament-forming species of the Saccharomycotina clade that are established at the incipient bud site or the hyphal tip respectively. In contrast, septum formation in the filament-forming Pezizomycotina species Aspergillus nidulans and Neurospora crassa seems more closely related to the fission yeast programme in that they may combine mitotic signals with a cell end-based marker system and Rho GTPase signalling. Thus, significant differences in the use and connection of conserved signalling modules become apparent that reflect the phylogenetic relationship of the analysed models.Deutsche Forschungsgemeinschaf
At the poles across kingdoms: phosphoinositides and polar tip growth
No full textPhosphoinositides (PIs) are minor, but essential phospholipid constituents of eukaryotic membranes, and are involved in the regulation of various physiological processes. Recent genetic and cell biological advances indicate that PIs play important roles in the control of polar tip growth in plant cells. In root hairs and pollen tubes, PIs control directional membrane trafficking required for the delivery of cell wall material and membrane area to the growing tip. So far, the exact mechanisms by which PIs control polarity and tip growth are unresolved. However, data gained from the analysis of plant, fungal and animal systems implicate PIs in the control of cytoskeletal dynamics, ion channel activity as well as vesicle trafficking. The present review aims at giving an overview of PI roles in eukaryotic cells with a special focus on functions pertaining to the control of cell polarity. Comparative screening of plant and fungal genomes suggests diversification of the PI system with increasing organismic complexity. The evolutionary conservation of the PI system among eukaryotic cells suggests a role for PIs in tip growing cells in models where PIs so far have not been a focus of attention, such as fungal hyphae
Hydrophobic Motif Phosphorylation Coordinates Activity and Polar Localization of the Neurospora crassa Nuclear Dbf2-Related Kinase COT1
No full textNuclear Dbf2p-related (NDR) kinases and associated proteins are recognized as a conserved network that regulates eukaryotic cell polarity. NDR kinases require association with MOB adaptor proteins and phosphorylation of two conserved residues in the activation segment and hydrophobic motif for activity and function. We demonstrate that the Neurospora crassa NDR kinase COT1 forms inactive dimers via a conserved N-terminal extension, which is also required for the interaction of the kinase with MOB2 to generate heterocomplexes with basal activity. Basal kinase activity also requires autophosphorylation of the COT1-MOB2 complex in the activation segment, while hydrophobic motif phosphorylation of COT1 by the germinal center kinase POD6 fully activates COT1 through induction of a conformational change. Hydrophobic motif phosphorylation is also required for plasma membrane association of the COT1-MOB2 complex. MOB2 further restricts the membrane-associated kinase complex to the hyphal apex to promote polar cell growth. These data support an integrated mechanism of NDR kinase regulation in vivo, in which kinase activation and cellular localization of COT1 are coordinated by dual phosphorylation and interaction with MOB2
Physiotherapy following a sport injury: Stability of psychological variables during rehabilitation
No full textThe present exploratory investigation in the interface between sports psychology and physiotherapy offers an indication of the stability of psychological variables in the course of rehabilitation. Variables were selected and repeatedly measured, following the model of Wiese?Bjornstal et al. (1998). In all cases, the timing of the measurements was determined on the basis of criteria related to the ability of dealing with stress. With distribution?free tests, it was analyzed whether the rank, mean ranking values, or the rank orders change within the group of 15 patients. A high stability was observed for adherence, intention to exercise, and fatalistic locus of control. The continuous decrease of anxiety was conspicuous and an abrupt drop in the social support was also perceived. The information given about satisfaction and the internal locus of control frequently varies over the course of rehabilitation. For research purposes, on the basis of these results a consideration of the stability of the variables is recommended in order to enhance the general validity and comparability of the results. The psychotherapist is advised to positively influence the formation of opinion in relation to his own locus of control as well as the anxiety of the patient in an early stage of rehabilitation
Ask questions, get sales : close the deak and create long-term relationships / Stephan Schiffman.
No full textIncludes index.v, 168 pages ;In Ask Questions, Get Sales, the author and sales guru Stephan Schiffman helps readers boost their careers to the gold-medal level by teaching them how to strengthen their questioning skills during the sales process. The premise is simple yet effective: In order to be successful, salespeople need to change their mindset from "need-orientated" to "do-orientated". The message of the book centers around six core "do" questions: What do you do? How do you do it? When and where do you do it? Why do you do it that way? Who do you do it with? How can we help you do it better? With this indispensable guide in their briefcase, salespeople will have information at the ready to score big sales over the short term and the long term
Regulation of Septum Formation by the Bud3-Rho4 GTPase Module in Aspergillus nidulans
No full textThe ability of fungi to generate polarized cells with a variety of shapes likely reflects precise temporal and spatial control over the formation of polarity axes. The bud site selection system of Saccharomyces cerevisiae represents the best-understood example of such a morphogenetic regulatory system. However, the extent to which this system is conserved in the highly polarized filamentous fungi remains unknown. Here, we describe the functional characterization and localization of the Aspergillus nidulans homolog of the axial bud site marker Bud3. Our results show that AnBud3 is not required for polarized hyphal growth per se, but is involved in septum formation. In particular, our genetic and biochemical evidence implicates AnBud3 as a guanine nucleotide exchange factor for the GTPase Rho4. Additional results suggest that the AnBud3-Rho4 module acts downstream of the septation initiation network to mediate recruitment of the formin SepA to the site of contractile actin ring assembly. Our observations provide new insight into the signaling pathways that regulate septum formation in filamentous fungi
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