@article{596, abstract = {The human Mediator complex controls RNA polymerase II (pol II) function in ways that remain incompletely understood. Activator-Mediator binding alters Mediator structure, and these activator-induced structural shifts appear to play key roles in regulating transcription. A recent cryo-electron microscopy (EM) analysis revealed that pol II adopted a stable orientation within a Mediator-pol II-TFIIF assembly in which Mediator was bound to the activation domain of viral protein 16 (VP16). Whereas TFIIF was shown to be important for orienting pol II within this assembly, the potential role of the activator was not assessed. To determine how activator binding might affect pol II orientation, we isolated human Mediator-pol II-TFIIF complexes in which Mediator was not bound to an activator. Cryo-EM analysis of this assembly, coupled with pol II crystal structure docking, revealed that pol II binds Mediator at the same general location; however, in contrast to VP16-bound Mediator, pol II does not appear to stably orient in the absence of an activator. Variability in pol II orientation might be important mechanistically, perhaps to enable sense and antisense transcription at human promoters. Because Mediator interacts extensively with pol II, these results suggest that Mediator structural shifts induced by activator binding help stably orient pol II prior to transcription initiation.}, author = {Bernecky, Carrie A and Taatjes, Dylan}, journal = {Journal of Molecular Biology}, number = {5}, pages = {387 -- 394}, publisher = {Elsevier}, title = {{Activator-mediator binding stabilizes RNA polymerase II orientation within the human mediator-RNA polymerase II-TFIIF assembly}}, doi = {10.1016/j.jmb.2012.02.014}, volume = {417}, year = {2012}, } @article{6136, abstract = {Tonic receptors convey stimulus duration and intensity and are implicated in homeostatic control. However, how tonic homeostatic signals are generated and how they reconfigure neural circuits and modify animal behavior is poorly understood. Here we show that Caenorhabditis elegans O2-sensing neurons are tonic receptors that continuously signal ambient [O2] to set the animal's behavioral state. Sustained signaling relied on a Ca2+ relay involving L-type voltage-gated Ca2+ channels, the ryanodine and the inositol-1,4,5-trisphosphate receptors. Tonic activity evoked continuous neuropeptide release, which helps elicit the enduring behavioral state associated with high [O2]. Sustained O2 receptor signaling was propagated to downstream neural circuits, including the hub interneuron RMG. O2 receptors evoked similar locomotory states at particular O2 concentrations, regardless of previous d[O2]/dt. However, a phasic component of the URX receptors' response to high d[O2]/dt, as well as tonic-to-phasic transformations in downstream interneurons, enabled transient reorientation movements shaped by d[O2]/dt. Our results highlight how tonic homeostatic signals can generate both transient and enduring behavioral change.}, author = {Busch, Karl Emanuel and Laurent, Patrick and Soltesz, Zoltan and Murphy, Robin Joseph and Faivre, Olivier and Hedwig, Berthold and Thomas, Martin and Smith, Heather L and de Bono, Mario}, issn = {1097-6256}, journal = {Nature Neuroscience}, number = {4}, pages = {581--591}, publisher = {Springer Nature}, title = {{Tonic signaling from O2 sensors sets neural circuit activity and behavioral state}}, doi = {10.1038/nn.3061}, volume = {15}, year = {2012}, } @inproceedings{6746, abstract = {This paper proposes a novel cooperative approach for two-hop amplify-and-forward (A&F) relaying that exploits both the signal forwarded by the relay and the one directly transmitted by the source in impulse-radio ultra-wideband (IR-UWB) systems. Specifically, we focus on a non-coherent setup employing a double-differential encoding scheme at the source node and a single differential demodulation at the relay and destination. The log-likelihood ratio based decision rule is derived at the destination node. A semi-analytical power allocation strategy is presented by evaluating a closed-form expression for the effective signal to noise ratio (SNR) at the destination, which is maximized by exhaustive search. Numerical simulations show that the proposed system outperforms both the direct transmission with single differential encoding and the non-cooperative multi-hop approach in different scenarios.}, author = {Mondelli, Marco and Zhou, Qi and Ma, Xiaoli and Lottici, Vincenzo}, booktitle = {2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)}, issn = {1520-6149}, location = {Kyoto, Japan}, pages = {2905--2908}, publisher = {IEEE}, title = {{A cooperative approach for amplify-and-forward differential transmitted reference IR-UWB relay systems}}, doi = {10.1109/icassp.2012.6288524}, year = {2012}, } @article{7074, abstract = {The Seebeck coefficients, electrical resistivities, total thermal conductivities, and magnetization are reported for temperatures between 5 and 350 K for n-type Bi0.88Sb0.12 nano-composite alloys made by Ho-doping at the 0, 1, and 3 % atomic levels. The alloys were prepared using a dc hot-pressing method, and are shown to be single phase for both Ho contents with grain sizes on the average of 900 nm. We find the parent compound has a maximum of ZT = 0.28 at 231 K, while doping 1 % Ho increases the maximum ZT to 0.31 at 221 K and the 3 % doped sample suppresses the maximum ZT = 0.24 at a temperature of 260 K.}, author = {Lukas, K. C. and Joshi, G. and Modic, Kimberly A and Ren, Z. F. and Opeil, C. P.}, issn = {1573-4803}, journal = {Journal of Materials Science}, number = {15}, pages = {5729--5734}, publisher = {Springer Nature}, title = {{Thermoelectric properties of Ho-doped Bi0.88Sb0.12}}, doi = {10.1007/s10853-012-6463-6}, volume = {47}, year = {2012}, } @article{7308, abstract = {Carbon has been used widely as the basis of porous cathodes for nonaqueous Li–O2 cells. However, the stability of carbon and the effect of carbon on electrolyte decomposition in such cells are complex and depend on the hydrophobicity/hydrophilicity of the carbon surface. Analyzing carbon cathodes, cycled in Li–O2 cells between 2 and 4 V, using acid treatment and Fenton’s reagent, and combined with differential electrochemical mass spectrometry and FTIR, demonstrates the following: Carbon is relatively stable below 3.5 V (vs Li/Li+) on discharge or charge, especially so for hydrophobic carbon, but is unstable on charging above 3.5 V (in the presence of Li2O2), oxidatively decomposing to form Li2CO3. Direct chemical reaction with Li2O2 accounts for only a small proportion of the total carbon decomposition on cycling. Carbon promotes electrolyte decomposition during discharge and charge in a Li–O2 cell, giving rise to Li2CO3 and Li carboxylates (DMSO and tetraglyme electrolytes). The Li2CO3 and Li carboxylates present at the end of discharge and those that form on charge result in polarization on the subsequent charge. Li2CO3 (derived from carbon and from the electrolyte) as well as the Li carboxylates (derived from the electrolyte) decompose and form on charging. Oxidation of Li2CO3 on charging to ∼4 V is incomplete; Li2CO3 accumulates on cycling resulting in electrode passivation and capacity fading. Hydrophilic carbon is less stable and more catalytically active toward electrolyte decomposition than carbon with a hydrophobic surface. If the Li–O2 cell could be charged at or below 3.5 V, then carbon may be relatively stable, however, its ability to promote electrolyte decomposition, presenting problems for its use in a practical Li–O2 battery. The results emphasize that stable cycling of Li2O2 at the cathode in a Li–O2 cell depends on the synergy between electrolyte and electrode; the stability of the electrode and the electrolyte cannot be considered in isolation.}, author = {Ottakam Thotiyl, Muhammed M. and Freunberger, Stefan Alexander and Peng, Zhangquan and Bruce, Peter G.}, issn = {0002-7863}, journal = {Journal of the American Chemical Society}, number = {1}, pages = {494--500}, publisher = {ACS}, title = {{The carbon electrode in nonaqueous Li–O2 cells}}, doi = {10.1021/ja310258x}, volume = {135}, year = {2012}, } @article{7309, abstract = {Energy‐storage technologies, including electrical double‐layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and “load leveling” of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double‐layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double‐layer capacitors.}, author = {Choi, Nam-Soon and Chen, Zonghai and Freunberger, Stefan Alexander and Ji, Xiulei and Sun, Yang-Kook and Amine, Khalil and Yushin, Gleb and Nazar, Linda F. and Cho, Jaephil and Bruce, Peter G.}, issn = {1433-7851}, journal = {Angewandte Chemie International Edition}, number = {40}, pages = {9994--10024}, publisher = {Wiley}, title = {{Challenges facing Lithium batteries and electrical double-layer capacitors}}, doi = {10.1002/anie.201201429}, volume = {51}, year = {2012}, } @article{7310, abstract = {The rechargeable nonaqueous lithium-air (Li-O2) battery is receiving a great deal of interest because, theoretically, its specific energy far exceeds the best that can be achieved with lithium-ion cells. Operation of the rechargeable Li-O2 battery depends critically on repeated and highly reversible formation/decomposition of lithium peroxide (Li2O2) at the cathode upon cycling. Here, we show that this process is possible with the use of a dimethyl sulfoxide electrolyte and a porous gold electrode (95% capacity retention from cycles 1 to 100), whereas previously only partial Li2O2 formation/decomposition and limited cycling could occur. Furthermore, we present data indicating that the kinetics of Li2O2 oxidation on charge is approximately 10 times faster than on carbon electrodes.}, author = {Peng, Z. and Freunberger, Stefan Alexander and Chen, Y. and Bruce, P. G.}, issn = {0036-8075}, journal = {Science}, number = {6094}, pages = {563--566}, publisher = {AAAS}, title = {{A reversible and higher-rate Li-O2 battery}}, doi = {10.1126/science.1223985}, volume = {337}, year = {2012}, } @article{7311, abstract = {Stability of the electrolyte toward reduced oxygen species generated at the cathode is a crucial challenge for the rechargeable nonaqueous Li–O2 battery. Here, we investigate dimethylformamide as the basis of an electrolyte. Although reactions at the O2 cathode on the first discharge–charge cycle are dominated by reversible Li2O2 formation/decomposition, there is also electrolyte decomposition, which increases on cycling. The products of decomposition at the cathode on discharge are Li2O2, Li2CO3, HCO2Li, CH3CO2Li, NO, H2O, and CO2. Li2CO3 accumulates in the electrode with cycling. The stability of dimethylformamide toward reduced oxygen species is insufficient for its use in the rechargeable nonaqueous Li–O2 battery.}, author = {Chen, Yuhui and Freunberger, Stefan Alexander and Peng, Zhangquan and Bardé, Fanny and Bruce, Peter G.}, issn = {0002-7863}, journal = {Journal of the American Chemical Society}, number = {18}, pages = {7952--7957}, publisher = {ACS}, title = {{Li–O2 battery with a dimethylformamide electrolyte}}, doi = {10.1021/ja302178w}, volume = {134}, year = {2012}, } @inproceedings{762, abstract = {Decades of research in distributed computing have led to a variety of perspectives on what it means for a concurrent algorithm to be efficient, depending on model assumptions, progress guarantees, and complexity metrics. It is therefore natural to ask whether one could compose algorithms that perform efficiently under different conditions, so that the composition preserves the performance of the original components when their conditions are met. In this paper, we evaluate the cost of composing shared-memory algorithms. First, we formally define the notion of safely composable algorithms and we show that every sequential type has a safely composable implementation, as long as enough state is transferred between modules. Since such generic implementations are inherently expensive, we present a more general light-weight specification that allows the designer to transfer very little state between modules, by taking advantage of the semantics of the implemented object. Using this framework, we implement a composed longlived test-and-set object, with the property that each of its modules is asymptotically optimal with respect to the progress condition it ensures, while the entire implementation only uses objects with consensus number at most two. Thus, we show that the overhead of composition can be negligible in the case of some important shared-memory abstractions.}, author = {Alistarh, Dan-Adrian and Guerraoui, Rachid and Kuznetsov, Petr and Losa, Giuliano}, pages = {298 -- 307}, publisher = {ACM}, title = {{On the cost of composing shared-memory algorithms}}, doi = {10.1145/2312005.2312057}, year = {2012}, } @inproceedings{763, abstract = {Renaming is a fundamental problem in distributed computing, in which a set of n processes need to pick unique names from a namespace of limited size. In this paper, we present the first early-deciding upper bounds for synchronous renaming, in which the running time adapts to the actual number of failures f in the execution. We show that, surprisingly, renaming can be solved in constant time if the number of failures f is limited to O(√n), while for general f ≤ n - 1 renaming can always be solved in O(log f) communication rounds. In the wait-free case, i.e. for f = n - 1, our upper bounds match the Ω(log n) lower bound of Chaudhuri et al. [13].}, author = {Alistarh, Dan-Adrian and Attiya, Hagit and Guerraoui, Rachid and Travers, Corentin}, pages = {195 -- 206}, publisher = {Springer}, title = {{Early deciding synchronous renaming in O(log f) rounds or less}}, doi = {10.1007/978-3-642-31104-8_17}, volume = {7355 LNCS}, year = {2012}, } @article{764, abstract = {Set agreement is a fundamental problem in distributed computing in which processes collectively choose a small subset of values from a larger set of proposals. The impossibility of fault-tolerant set agreement in asynchronous networks is one of the seminal results in distributed computing. In synchronous networks, too, the complexity of set agreement has been a significant research challenge that has now been resolved. Real systems, however, are neither purely synchronous nor purely asynchronous. Rather, they tend to alternate between periods of synchrony and periods of asynchrony. Nothing specific is known about the complexity of set agreement in such a "partially synchronous" setting. In this paper, we address this challenge, presenting the first (asymptotically) tight bound on the complexity of set agreement in such systems. We introduce a novel technique for simulating, in a fault-prone asynchronous shared memory, executions of an asynchronous and failure-prone message-passing system in which some fragments appear synchronous to some processes. We use this simulation technique to derive a lower bound on the round complexity of set agreement in a partially synchronous system by a reduction from asynchronous wait-free set agreement. Specifically, we show that every set agreement protocol requires at least $\lfloor\frac t k \rfloor + 2$ synchronous rounds to decide. We present an (asymptotically) matching algorithm that relies on a distributed asynchrony detection mechanism to decide as soon as possible during periods of synchrony. From these two results, we derive the size of the minimal window of synchrony needed to solve set agreement. By relating synchronous, asynchronous and partially synchronous environments, our simulation technique is of independent interest. In particular, it allows us to obtain a new lower bound on the complexity of early deciding k-set agreement complementary to that of Gafni et al. (in SIAM J. Comput. 40(1):63-78, 2011), and to re-derive the combinatorial topology lower bound of Guerraoui et al. (in Theor. Comput. Sci. 410(6-7):570-580, 2009) in an algorithmic way.}, author = {Alistarh, Dan-Adrian and Gilbert, Seth and Guerraoui, Rachid and Travers, Corentin}, journal = {Algorithmica (New York)}, number = {1-2}, pages = {595 -- 629}, publisher = {Springer}, title = {{Of choices, failures and asynchrony: the many faces of set agreement}}, doi = {10.1007/s00453-011-9581-7}, volume = {62}, year = {2012}, } @inproceedings{766, abstract = {Asynchronous task allocation is a fundamental problem in distributed computing in which p asynchronous processes must execute a set of m tasks. Also known as write-all or do-all, this problem been studied extensively, both independently and as a key building block for various distributed algorithms. In this paper, we break new ground on this classic problem: we introduce the To-Do Tree concurrent data structure, which improves on the best known randomized and deterministic upper bounds. In the presence of an adaptive adversary, the randomized To-Do Tree algorithm has O(m + p log p log2 m) work complexity. We then show that there exists a deterministic variant of the To-Do Tree algorithm with work complexity O(m + p log5 m log2 max(m, p)). For all values of m and p, our algorithms are within log factors of the Ω(m + p log p) lower bound for this problem. The key technical ingredient in our results is a new approach for analyzing concurrent executions against a strong adaptive scheduler. This technique allows us to handle the complex dependencies between the processes' coin flips and their scheduling, and to tightly bound the work needed to perform subsets of the tasks.}, author = {Alistarh, Dan-Adrian and Bender, Michael and Gilbert, Seth and Guerraoui, Rachid}, pages = {331 -- 340}, publisher = {IEEE}, title = {{How to allocate tasks asynchronously}}, doi = {10.1109/FOCS.2012.41}, year = {2012}, } @article{767, abstract = {Synchronous distributed algorithms are easier to design and prove correct than algorithms that tolerate asynchrony. Yet, in the real world, networks experience asynchrony and other timing anomalies. In this paper, we address the question of how to efficiently transform an algorithm that relies on synchronous timing into an algorithm that tolerates asynchronous executions. We introduce a transformation technique from synchronous algorithms to indulgent algorithms (Guerraoui, in PODC, pp. 289-297, 2000), which induces only a constant overhead in terms of time complexity in well-behaved executions. Our technique is based on a new abstraction we call an asynchrony detector, which the participating processes implement collectively. The resulting transformation works for the class of colorless distributed tasks, including consensus and set agreement. Interestingly, we also show that our technique is relevant for colored tasks, by applying it to the renaming problem, to obtain the first indulgent renaming algorithm.}, author = {Alistarh, Dan-Adrian and Gilbert, Seth and Guerraoui, Rachid and Travers, Corentin}, journal = {Theory of Computing Systems}, number = {4}, pages = {404 -- 424}, publisher = {Elsevier}, title = {{Generating Fast Indulgent Algorithms}}, doi = {10.1007/s00224-012-9407-2}, volume = {51}, year = {2012}, } @article{7749, abstract = {Although studies on laboratory species and natural populations of vertebrates have shown reproduction to impair later performance, little is known of the age‐specific associations between reproduction and survival, and how such findings apply to the ageing of large, long‐lived species. Herein we develop a framework to examine population‐level patterns of reproduction and survival across lifespan in long‐lived organisms, and decompose those changes into individual‐level effects, and the effects of age‐specific trade‐offs between fitness components. We apply this to an extensive longitudinal dataset on female semi‐captive Asian timber elephants (Elephas maximus) and report the first evidence of age‐specific fitness declines that are driven by age‐specific associations between fitness components in a long‐lived mammal. Associations between reproduction and survival are positive in early life, but negative in later life with up to 71% of later‐life survival declines associated with investing in the production of offspring within this population of this critically endangered species.}, author = {Robinson, Matthew Richard and Mar, Khyne U and Lummaa, Virpi}, issn = {1461-023X}, journal = {Ecology Letters}, number = {3}, pages = {260--266}, publisher = {Wiley}, title = {{Senescence and age-specific trade-offs between reproduction and survival in female Asian elephants}}, doi = {10.1111/j.1461-0248.2011.01735.x}, volume = {15}, year = {2012}, } @article{7748, abstract = {Female mate choice acts as an important evolutionary force, yet the influence of the environment on both its expression and the selective pressures acting upon it remains unknown. We found consistent heritable differences between females in their choice of mate based on ornament size during a 25‐year study of a population of collared flycatchers. However, the fitness consequences of mate choice were dependent on environmental conditions experienced whilst breeding. Females breeding with highly ornamented males experienced high relative fitness during dry summer conditions, but low relative fitness during wetter years. Our results imply that sexual selection within a population can be highly variable and dependent upon the prevailing weather conditions experienced by individuals.}, author = {Robinson, Matthew Richard and Sander van Doorn, G. and Gustafsson, Lars and Qvarnström, Anna}, issn = {1461-023X}, journal = {Ecology Letters}, number = {6}, pages = {611--618}, publisher = {Wiley}, title = {{Environment-dependent selection on mate choice in a natural population of birds}}, doi = {10.1111/j.1461-0248.2012.01780.x}, volume = {15}, year = {2012}, } @article{7776, abstract = {We present an analysis of finite-size effects in jammed packings of N soft, frictionless spheres at zero temperature. There is a 1/N correction to the discrete jump in the contact number at the transition so that jammed packings exist only above isostaticity. As a result, the canonical power-law scalings of the contact number and elastic moduli break down at low pressure. These quantities exhibit scaling collapse with a nontrivial scaling function, demonstrating that the jamming transition can be considered a phase transition. Scaling is achieved as a function of N in both two and three dimensions, indicating an upper critical dimension of 2.}, author = {Goodrich, Carl Peter and Liu, Andrea J. and Nagel, Sidney R.}, issn = {0031-9007}, journal = {Physical Review Letters}, number = {9}, publisher = {American Physical Society}, title = {{Finite-size scaling at the jamming transition}}, doi = {10.1103/physrevlett.109.095704}, volume = {109}, year = {2012}, } @article{801, abstract = {Fungal cell walls frequently contain a polymer of mannose and galactose called galactomannan. In the pathogenic filamentous fungus Aspergillus fumigatus, this polysaccharide is made of a linear mannan backbone with side chains of galactofuran and is anchored to the plasma membrane via a glycosylphosphatidylinositol or is covalently linked to the cell wall. To date, the biosynthesis and significance of this polysaccharide are unknown. The present data demonstrate that deletion of the Golgi UDP-galactofuranose transporter GlfB or the GDP-mannose transporter GmtA leads to the absence of galactofuran or galactomannan, respectively. This indicates that the biosynthesis of galactomannan probably occurs in the lumen of the Golgi apparatus and thus contrasts with the biosynthesis of other fungal cell wall polysaccharides studied to date that takes place at the plasma membrane. Transglycosylation of galactomannan from the membrane to the cell wall is hypothesized because both the cell wall-bound and membrane-bound polysaccharide forms are affected in the generated mutants. Considering the severe growth defect of the A. fumigatus GmtA-deficient mutant, proving this paradigm might provide new targets for antifungal therapy.}, author = {Engel, Jakob and Schmalhorst, Philipp S and Routier, Françoise}, journal = {Journal of Biological Chemistry}, number = {53}, pages = {44418 -- 44424}, publisher = {American Society for Biochemistry and Molecular Biology}, title = {{Biosynthesis of the fungal cell wall polysaccharide galactomannan requires intraluminal GDP-mannose}}, doi = {10.1074/jbc.M112.398321}, volume = {287}, year = {2012}, } @article{8024, abstract = {In dynamical models of cortical networks, the recurrent connectivity can amplify the input given to the network in two distinct ways. One is induced by the presence of near-critical eigenvalues in the connectivity matrix W, producing large but slow activity fluctuations along the corresponding eigenvectors (dynamical slowing). The other relies on W not being normal, which allows the network activity to make large but fast excursions along specific directions. Here we investigate the trade-off between non-normal amplification and dynamical slowing in the spontaneous activity of large random neuronal networks composed of excitatory and inhibitory neurons. We use a Schur decomposition of W to separate the two amplification mechanisms. Assuming linear stochastic dynamics, we derive an exact expression for the expected amount of purely non-normal amplification. We find that amplification is very limited if dynamical slowing must be kept weak. We conclude that, to achieve strong transient amplification with little slowing, the connectivity must be structured. We show that unidirectional connections between neurons of the same type together with reciprocal connections between neurons of different types, allow for amplification already in the fast dynamical regime. Finally, our results also shed light on the differences between balanced networks in which inhibition exactly cancels excitation and those where inhibition dominates.}, author = {Hennequin, Guillaume and Vogels, Tim P and Gerstner, Wulfram}, issn = {1539-3755}, journal = {Physical Review E}, number = {1}, publisher = {American Physical Society}, title = {{Non-normal amplification in random balanced neuronal networks}}, doi = {10.1103/physreve.86.011909}, volume = {86}, year = {2012}, } @article{808, abstract = {Using correlated live-cell imaging and electron tomography we found that actin branch junctions in protruding and treadmilling lamellipodia are not concentrated at the front as previously supposed, but link actin filament subsets in which there is a continuum of distances from a junction to the filament plus ends, for up to at least 1 mm. When branch sites were observed closely spaced on the same filament their separation was commonly a multiple of the actin helical repeat of 36 nm. Image averaging of branch junctions in the tomograms yielded a model for the in vivo branch at 2.9 nm resolution, which was comparable with that derived for the in vitro actin- Arp2/3 complex. Lamellipodium initiation was monitored in an intracellular wound-healing model and was found to involve branching from the sides of actin filaments oriented parallel to the plasmalemma. Many filament plus ends, presumably capped, terminated behind the lamellipodium tip and localized on the dorsal and ventral surfaces of the actin network. These findings reveal how branching events initiate and maintain a network of actin filaments of variable length, and provide the first structural model of the branch junction in vivo. A possible role of filament capping in generating the lamellipodium leaflet is discussed and a mathematical model of protrusion is also presented.}, author = {Vinzenz, Marlene and Nemethova, Maria and Schur, Florian and Mueller, Jan and Narita, Akihiro and Urban, Edit and Winkler, Christoph and Schmeiser, Christian and Koestler, Stefan and Rottner, Klemens and Resch, Guenter and Maéda, Yuichiro and Small, John}, journal = {Journal of Cell Science}, number = {11}, pages = {2775 -- 2785}, publisher = {Company of Biologists}, title = {{Actin branching in the initiation and maintenance of lamellipodia}}, doi = {10.1242/jcs.107623}, volume = {125}, year = {2012}, } @article{8246, abstract = {The Staphylococcus aureus cell wall stress stimulon (CWSS) is activated by cell envelope-targeting antibiotics or depletion of essential cell wall biosynthesis enzymes. The functionally uncharacterized S. aureus LytR-CpsA-Psr (LCP) proteins, MsrR, SA0908 and SA2103, all belong to the CWSS. Although not essential, deletion of all three LCP proteins severely impairs cell division. We show here that VraSR-dependent CWSS expression was up to 250-fold higher in single, double and triple LCP mutants than in wild type S. aureus in the absence of external stress. The LCP triple mutant was virtually depleted of wall teichoic acids (WTA), which could be restored to different degrees by any of the single LCP proteins. Subinhibitory concentrations of tunicamycin, which inhibits the first WTA synthesis enzyme TarO (TagO), could partially complement the severe growth defect of the LCP triple mutant. Both of the latter findings support a role for S. aureus LCP proteins in late WTA synthesis, as in Bacillus subtilis where LCP proteins were recently proposed to transfer WTA from lipid carriers to the cell wall peptidoglycan. Intrinsic activation of the CWSS upon LCP deletion and the fact that LCP proteins were essential for WTA-loading of the cell wall, highlight their important role(s) in S. aureus cell envelope biogenesis.}, author = {Dengler, Vanina and Meier, Patricia Stutzmann and Heusser, Ronald and Kupferschmied, Peter and Fazekas, Judit and Friebe, Sarah and Staufer, Sibylle Burger and Majcherczyk, Paul A. and Moreillon, Philippe and Berger-Bächi, Brigitte and McCallum, Nadine}, issn = {0378-1097}, journal = {FEMS Microbiology Letters}, number = {2}, pages = {109--120}, publisher = {Oxford University Press}, title = {{Deletion of hypothetical wall teichoic acid ligases in Staphylococcus aureus activates the cell wall stress response}}, doi = {10.1111/j.1574-6968.2012.02603.x}, volume = {333}, year = {2012}, }