@article{4227, abstract = {Morphogen concentration gradients provide positional information by activating target genes in a concentration-dependent manner. Recent reports show that the gradient of the syncytial morphogen Bicoid seems to provide precise positional information to determine target gene domains. For secreted morphogenetic ligands, the precision of the gradients, the signal transduction and the reliability of target gene expression domains have not been studied. Here we investigate these issues for the TGF-beta-type morphogen Dpp. We first studied theoretically how cell-to-cell variability in the source, the target tissue, or both, contribute to the variations of the gradient. Fluctuations in the source and target generate a local maximum of precision at a finite distance to the source. We then determined experimentally in the wing epithelium: (1) the precision of the Dpp concentration gradient; (2) the precision of the Dpp signaling activity profile; and (3) the precision of activation of the Dpp target gene spalt. As captured by our theoretical description, the Dpp gradient provides positional information with a maximal precision a few cells away from the source. This maximal precision corresponds to a positional uncertainly of about a single cell diameter. The precision of the Dpp gradient accounts for the precision of the spalt expression range, implying that Dpp can act as a morphogen to coarsely determine the expression pattern of target genes.}, author = {Bollenbach, Tobias and Pantazis, Periklis and Kicheva, Anna and Bokel, Christian and González Gaitán, Marcos and Julicher, Frank}, journal = {Development}, number = {6}, pages = {1137 -- 1146}, publisher = {Company of Biologists}, title = {{Precision of the Dpp gradient}}, doi = {10.1242/dev.012062}, volume = {135}, year = {2008}, } @article{4198, abstract = {Animal body plan arises during gastrulation and organogenesis by the coordination of inductive events and cell movements. Several signaling pathways, such as BMP, FGF, Hedgehog, Nodal, and Wnt have well-recognized instructive roles in cell fate specification during vertebrate embryogenesis. Growing evidence indicates that BMP, Nodal, and FGF signaling also regulate cell movements, and that they do so through mechanisms distinct from those that specify cell fates. Moreover, pathways controlling cell movements can also indirectly influence cell fate specification by regulating dimensions and relative positions of interacting tissues. The current challenge is to delineate the molecular mechanisms via which the major signaling pathways regulate cell fate specification and movements, and how these two processes are coordinated to ensure normal development.}, author = {Heisenberg, Carl-Philipp J and Solnica Krezel, Lilianna}, issn = {1879-0380}, journal = {Current Opinion in Genetics & Development}, number = {4}, pages = {311 -- 316}, publisher = {Elsevier}, title = {{Back and forth between cell fate specification and movement during vertebrate gastrulation}}, doi = {10.1016/j.gde.2008.07.011}, volume = {18}, year = {2008}, } @inproceedings{4244, abstract = {This paper presents a new approach to optimization of an energy-constrained modulation scheme for wireless sensor networks by taking advantage of a novel bio-inspired optimization algorithm. The algorithm is inspired by Wrightpsilas shifting balance theory (SBT) of evolution in population genetics. The total energy consumption of an energy-constrained modulation scheme is minimized by using the new SBT-based optimization algorithm. The results obtained by this new algorithm are compared with other popular optimization algorithms. Numerical experiments are performed to demonstrate that the SBT-based algorithm could be used as an efficient optimizer for solving the optimization problems arising from currently emerging energy-efficient wireless sensor networks.}, author = {Yang, Erfu and Barton, Nicholas H and Arslan, Tughrul and Erdogan, Ahmet}, isbn = {9781424418237}, location = {Hong Kong}, pages = {2749 -- 2756}, publisher = {IEEE}, title = {{A novel shifting balance theory-based approach to optimization of an energy-constrained modulation scheme for wireless sensor networks}}, doi = {10.1109/CEC.2008.4631167}, year = {2008}, } @article{4161, abstract = {Handedness of the vertebrate body plan critically depends on transient embryonic structures/ organs that generate cilia-dependent leftward fluid flow within constrained extracellular environments. Although the function of ciliated organs in laterality determination has been extensively studied, how they are formed during embryogenesis is still poorly understood. Here we show that Kupffer's vesicle (KV), the zebrafish organ of laterality, arises from a surface epithelium previously thought to adopt exclusively extra-embryonic fates. Live multi-photon confocal imaging reveals that surface epithelial cells undergo Nodal/TGF beta signalling-dependent ingression at the dorsal germ ring margin prior to gastrulation, to give rise to dorsal forerunner cells (DFCs), the precursors of KV. DFCs then migrate attached to the overlying surface epithelium and rearrange into rosette-like epithelial structures at the end of gastrulation. During early somitogenesis, these epithelial rosettes coalesce into a single rosette that differentiates into the KV with a ciliated lumen at its apical centre. Our results provide novel insights into the morphogenetic transformations that shape the laterality organ in zebrafish and suggest a conserved progenitor role of the surface epithelium during laterality organ formation in vertebrates.}, author = {Oteíza, Pablo and Köppen, Mathias and Concha, Miguel and Heisenberg, Carl-Philipp J}, issn = {1477-9129}, journal = {Development}, number = {16}, pages = {2807 -- 2813}, publisher = {Company of Biologists}, title = {{Origin and shaping of the laterality organ in zebrafish}}, doi = {10.1242/dev.022228}, volume = {135}, year = {2008}, } @article{4181, abstract = {Understanding the factors that direct tissue organization during development is one of the most fundamental goals in developmental biology. Various hypotheses explain cell sorting and tissue organization on the basis of the adhesive and mechanical properties of the constituent cells(1). However, validating these hypotheses has been difficult due to the lack of appropriate tools to measure these parameters. Here we use atomic force microscopy ( AFM) to quantify the adhesive and mechanical properties of individual ectoderm, mesoderm and endoderm progenitor cells from gastrulating zebrafish embryos. Combining these data with tissue self-assembly in vitro and the sorting behaviour of progenitors in vivo, we have shown that differential actomyosin-dependent cell-cortex tension, regulated by Nodal/ TGF beta-signalling ( transforming growth factor beta), constitutes a key factor that directs progenitor-cell sorting. These results demonstrate a previously unrecognized role for Nodal-controlled cell-cortex tension in germ-layer organization during gastrulation.}, author = {Krieg, Michael and Arboleda Estudillo, Yohanna and Puech, Pierre and Käfer, Jos and Graner, François and Mueller, Daniel and Heisenberg, Carl-Philipp J}, issn = {1476-4679}, journal = {Nature Cell Biology}, number = {4}, pages = {429 -- 436}, publisher = {Nature Publishing Group}, title = {{Tensile forces govern germ-layer organization in zebrafish}}, doi = {10.1038/ncb1705}, volume = {10}, year = {2008}, } @article{4180, abstract = {(Figure Presented) The name's Bond: Separated cells form membranous nanotubes whose tips are tethered by adhesive bonds (see picture). The lifetime of receptor-ligand interactions can be measured by using membrane nanotubes of living cells as constant force actuators. Because the nanotubes are extruded from living cells at conditions approaching the physiological, cellular processes can be both studied and utilized. }, author = {Krieg, Michael and Helenius, Jonne and Heisenberg, Carl-Philipp J and Mueller, Daniel}, issn = {1521-3773}, journal = {Angewandte Chemie - International Edition}, number = {50}, pages = {9775 -- 9777}, publisher = {Wiley-Blackwell}, title = {{A Bond for a Lifetime: Employing Membrane Nanotubes from Living Cells to Determine Receptor-Ligand Kinetics}}, doi = {10.1002/anie.200803552}, volume = {47}, year = {2008}, } @article{4141, abstract = {The zyxin-related LPP protein is localized at focal adhesions and cell-cell contacts and is involved in the regulation of smooth muscle cell migration. A known interaction partner of LPP in human is the tumor suppressor protein SCRIB. Knocking down scrib expression c uring zebrafish embryonic development results in defects of convergence and extension (C&E) movements, which occur during gastrulation and mediate elongation of the anterior-posterior body axis. Mediolateral cell polarization underlying C&E is regulated by a noncanonical Writ signaling pathway constituting the vertebrate planar cell polarity (PCP) pathway. Here, we investigated the role of Lpp during early zebrafish development. We show that morpholino knockdown of Ipp results in defects of C&E, phenocopying noncanonical Wnt signaling mutants. Time-lapse analysis associates the defective dorsal convergence movements with a reduced ability to migrate along straight paths. In addition, expression of Lpp is significantly reduced in Wnt11 morphants and in embryos overexpressing Wnt11 or a dominant-negative form of Rho kinase 2, which is a downstream effector of Wnt11, Suggesting that Lpp expression is dependent on noncanonical Wnt signaling. Finally, we demonstrate that Lpp interacts with the PCP protein Scrib in zebrafish, and that Lpp and Scrib cooperate for the mediation of C&E. (C) 2008 Elsevier Inc. All rights reserved.}, author = {Vervenne, Hilke and Crombez, Koen and Lambaerts, Kathleen and Carvalho, Lara and Köppen, Mathias and Heisenberg, Carl-Philipp J and Van De Ven, Wim and Petit, Marleen}, issn = {0012-1606}, journal = {Developmental Biology}, number = {1}, pages = {267 -- 277}, publisher = {Elsevier}, title = {{Lpp is involved in Wnt/PCP signaling and acts together with Scrib to mediate convergence and extension movements during zebrafish gastrulation}}, doi = {10.1016/j.ydbio.2008.05.529}, volume = {320}, year = {2008}, } @inproceedings{3974, abstract = {Generalizing the concept of a Reeb graph, the Reeb space of a multivariate continuous mapping identifies points of the domain that belong to a common component of the preimage of a point in the range. We study the local and global structure of this space for generic, piecewise linear mappings on a combinatorial manifold.}, author = {Edelsbrunner, Herbert and Harer, John and Patel, Amit}, booktitle = {Proceedings of the twenty-fourth annual symposium on Computational geometry}, isbn = {9781605580715}, location = {College Park, MD, United States}, pages = {242 -- 250}, publisher = {Association for Computing Machinery}, title = {{Reeb spaces of piecewise linear mappings}}, doi = {10.1145/1377676.1377720}, year = {2008}, } @article{3945, abstract = {Langerhans cells and dermal dendritic cells migrate to the draining lymph nodes through dermal lymphatic vessels. They do so in the steady-state and under inflammatory conditions. Peripheral T cell tolerance or T cell priming, respectively, are the consequences of migration. The nature of dendritic cell-containing vessels was mostly defined by electron microscopy or by their lack of blood endothelial markers. Selective markers for murine lymph endothelium were hitherto rare or not available. Here, we utilised recently developed antibodies against the murine hyaluronan receptor, LYVE-1, to study the lymph vessel network in mouse skin in more detail. In hairless skin from the ears, lymph vessels were spread out in a horizontal plane. They formed anastomoses, and they possessed frequent blind endings that were occasionally open. Lymph vessels were wider than blood vessels, which were identified by their strong CD31 expression. In body wall skin LYVE-1 reactive vessels did not extend laterally but they dived straight down into the deeper dermis. There, they are connected to each other and formed a network similar to ear skin. The number and width of lymph vessels did not grossly change upon inflammatory stimuli such as skin explant culture or tape stripping. There were also no marked changes in caliber in response to the TLR 7/8 ligand Imiquimod. Double-labelling experiments of cultured skin showed that most of the strongly cell surface MHC II-expressing (i.e. activated) dendritic cells were confined to the lymph vessels. Langerin/CD207(+) cells within this population appeared later than dermal dendritic cells, i.e. langerin-negative cells. Comparable results were obtained after stimulating the skin in vivo with the TLR 7/8 ligand Imiquimod or by tape stripping. In untreated skin (i.e. steady state) a few MHC II(+) and Langerin/CD207(+) cells, presumably migrating skin dendritic cells including epidermal Langerhans cells, were consistently observed within the lymph vessels. The novel antibody reagents may serve as important tools to further study the dendritic cell traffic in the skin under physiological conditions as well as in conditions of adoptive dendritic cell transfer in immunotherapy.}, author = {Tripp, Christoph and Haid, Bernhard and Flacher, Vincent and Sixt, Michael K and Peter, Hannes and Farkas, Julia and Gschwentner, Robert and Sorokin, Lydia and Romani, Nikolaus and Stoitzner, Patrizia}, issn = {1878-3279}, journal = {Immunobiology}, number = {9-10}, pages = {715 -- 728}, publisher = {Elsevier}, title = {{The lymph vessel network in mouse skin visualised with antibodies against the hyaluronan receptor LYVE-1}}, doi = {10.1016/j.imbio.2008.07.025}, volume = {213}, year = {2008}, } @article{3970, abstract = {While genome-wide gene expression data are generated at an increasing rate, the repertoire of approaches for pattern discovery in these data is still limited. Identifying subtle patterns of interest in large amounts of data (tens of thousands of profiles) associated with a certain level of noise remains a challenge. A microarray time series was recently generated to study the transcriptional program of the mouse segmentation clock, a biological oscillator associated with the periodic formation of the segments of the body axis. A method related to Fourier analysis, the Lomb-Scargle periodogram, was used to detect periodic profiles in the dataset, leading to the identification of a novel set of cyclic genes associated with the segmentation clock. Here, we applied to the same microarray time series dataset four distinct mathematical methods to identify significant patterns in gene expression profiles. These methods are called: Phase consistency, Address reduction, Cyclohedron test and Stable persistence, and are based on different conceptual frameworks that are either hypothesis- or data-driven. Some of the methods, unlike Fourier transforms, are not dependent on the assumption of periodicity of the pattern of interest. Remarkably, these methods identified blindly the expression profiles of known cyclic genes as the most significant patterns in the dataset. Many candidate genes predicted by more than one approach appeared to be true positive cyclic genes and will be of particular interest for future research. In addition, these methods predicted novel candidate cyclic genes that were consistent with previous biological knowledge and experimental validation in mouse embryos. Our results demonstrate the utility of these novel pattern detection strategies, notably for detection of periodic profiles, and suggest that combining several distinct mathematical approaches to analyze microarray datasets is a valuable strategy for identifying genes that exhibit novel, interesting transcriptional patterns.}, author = {Dequéant, Mary and Ahnert, Sebastian and Edelsbrunner, Herbert and Fink, Thomas and Glynn, Earl and Hattem, Gaye and Kudlicki, Andrzej and Mileyko, Yuriy and Morton, Jason and Mushegian, Arcady and Pachter, Lior and Rowicka, Maga and Shiu, Anne and Sturmfels, Bernd and Pourquie, Olivier}, issn = {1932-6203}, journal = {PLoS One}, number = {8}, publisher = {Public Library of Science}, title = {{Comparison of pattern detection methods in microarray time series of the segmentation clock}}, doi = {10.1371/journal.pone.0002856}, volume = {3}, year = {2008}, } @article{3942, abstract = {Recent in vitro studies have suggested a role for sialylation in chemokine receptor binding to its ligand (Bannert, N., S. Craig, M. Farzan, D. Sogah, N.V. Santo, H. Choe, and J. Sodroski. 2001. J. Exp. Med. 194:1661-1673). This prompted us to investigate chemokine-induced leukocyte adhesion in inflamed cremaster muscle venules of alpha2,3 sialyltransferase (ST3Gal-IV)-deficient mice. We found a marked reduction in leukocyte adhesion to inflamed microvessels upon injection of the CXCR2 ligands CXCL1 (keratinocyte-derived chemokine) or CXCL8 (interleukin 8). In addition, extravasation of ST3Gal-IV(-/-) neutrophils into thioglycollate-pretreated peritoneal cavities was significantly decreased. In vitro assays revealed that CXCL8 binding to isolated ST3Gal-IV(-/-) neutrophils was markedly impaired. Furthermore, CXCL1-mediated adhesion of ST3Gal-IV(-/-) leukocytes at physiological flow conditions, as well as transendothelial migration of ST3Gal-IV(-/-) leukocytes in response to CXCL1, was significantly reduced. In human neutrophils, enzymatic desialylation decreased binding of CXCR2 ligands to the neutrophil surface and diminished neutrophil degranulation in response to these chemokines. In addition, binding of alpha2,3-linked sialic acid-specific Maackia amurensis lectin II to purified CXCR2 from neuraminidase-treated CXCR2-transfected HEK293 cells was markedly impaired. Collectively, we provide substantial evidence that sialylation by ST3Gal-IV significantly contributes to CXCR2-mediated leukocyte adhesion during inflammation in vivo.}, author = {Frommhold, David and Ludwig, Andreas and Bixel, M Gabriele and Zarbock, Alexander and Babushkina, Inna and Weissinger, Melitta and Cauwenberghs, Sandra and Ellies, Lesley and Marth, Jamey and Beck Sickinger, Annette and Sixt, Michael K and Lange Sperandio, Bärbel and Zernecke, Alma and Brandt, Ernst and Weber, Christian and Vestweber, Dietmar and Ley, Klaus and Sperandio, Markus}, issn = {1540-9538}, journal = {The Journal of Experimental Medicine}, number = {6}, pages = {1435 -- 1446}, publisher = {Rockefeller University Press}, title = {{Sialyltransferase ST3Gal-IV controls CXCR2-mediated firm leukocyte arrest during inflammation}}, doi = {10.1084/jem.20070846}, volume = {205}, year = {2008}, } @article{3943, abstract = {Neutrophil granulocytes form the body's first line of antibacterial defense, but they also contribute to tissue injury and noninfectious, chronic inflammation. Proteinase 3 (PR3) and neutrophil elastase (NE) are 2 abundant neutrophil serine proteases implicated in antimicrobial defense with overlapping and potentially redundant substrate specificity. Here, we unraveled a cooperative role for PR3 and NE in neutrophil activation and noninfectious inflammation in vivo, which we believe to be novel. Mice lacking both PR3 and NE demonstrated strongly diminished immune complex-mediated (IC-mediated) neutrophil infiltration in vivo as well as reduced activation of isolated neutrophils by ICs in vitro. In contrast, in mice lacking just NE, neutrophil recruitment to ICs was only marginally impaired. The defects in mice lacking both PR3 and NE were directly linked to the accumulation of antiinflammatory progranulin (PGRN). Both PR3 and NE cleaved PGRN in vitro and during neutrophil activation and inflammation in vivo. Local administration of recombinant PGRN potently inhibited neutrophilic inflammation in vivo, demonstrating that PGRN represents a crucial inflammation-suppressing mediator. We conclude that PR3 and NE enhance neutrophil-dependent inflammation by eliminating the local antiinflammatory activity of PGRN. Our results support the use of serine protease inhibitors as antiinflammatory agents.}, author = {Kessenbrock, Kai and Fröhlich, Leopold and Sixt, Michael K and Lämmermann, Tim and Pfister, Heiko and Bateman, Andrew and Belaaouaj, Azzaq and Ring, Johannes and Ollert, Markus and Fässler, Reinhard and Jenne, Dieter}, issn = {1558-8238}, journal = {The Journal of Clinical Investigation}, number = {7}, pages = {2438 -- 2447}, publisher = {American Society for Clinical Investigation}, title = {{Proteinase 3 and neutrophil elastase enhance inflammation in mice by inactivating antiinflammatory progranulin}}, doi = {10.1172/JCI34694}, volume = {118}, year = {2008}, } @article{3944, abstract = {Live imaging of the actin cytoskeleton is crucial for the study of many fundamental biological processes, but current approaches to visualize actin have several limitations. Here we describe Lifeact, a 17-amino-acid peptide, which stained filamentous actin (F-actin) structures in eukaryotic cells and tissues. Lifeact did not interfere with actin dynamics in vitro and in vivo and in its chemically modified peptide form allowed visualization of actin dynamics in nontransfectable cells.}, author = {Riedl, Julia and Crevenna, Alvaro and Kessenbrock, Kai and Yu, Jerry and Neukirchen, Dorothee and Bista, Michal and Bradke, Frank and Jenne, Dieter and Holak, Tad and Werb, Zena and Sixt, Michael K and Wedlich Soldner, Roland}, issn = {1548-7105}, journal = {Nature Methods}, number = {7}, pages = {605 -- 607}, publisher = {Nature Publishing Group}, title = {{Lifeact: a versatile marker to visualize F-actin}}, doi = {10.1038/nmeth.1220}, volume = {5}, year = {2008}, } @article{3971, abstract = {The Reeb graph is a useful tool in visualizing real-valued data obtained from computational simulations of physical processes. We characterize the evolution of the Reeb graph of a time-varying continuous function defined in three-dimensional space. We show how to maintain the Reeb graph over time and compress the entire sequence of Reeb graphs into a single, partially persistent data structure, and augment this data structure with Betti numbers to describe the topology of level sets and with path seeds to assist in the fast extraction of level sets for visualization.}, author = {Edelsbrunner, Herbert and Harer, John and Mascarenhas, Ajith and Pascucci, Valerio and Snoeyink, Jack}, issn = {1879-081X}, journal = {Computational Geometry: Theory and Applications}, number = {3}, pages = {149 -- 166}, publisher = {Elsevier}, title = {{Time-varying Reeb graphs for continuous space-time data}}, doi = {10.1016/j.comgeo.2007.11.001}, volume = {41}, year = {2008}, } @article{3905, abstract = {Winged and wingless males coexist in the ant Cardiocondyla obscurior. Wingless (“ergatoid”) males never leave their maternal colony and fight remorselessly among each other for the access to emerging females. The peaceful winged males disperse after about 10 days, but beforehand also mate in the nest. In the first 5 days of their life, winged males perform a chemical female mimicry that protects them against attack and even makes them sexually attractive to ergatoid males. When older, the chemical profile of winged males no longer matches that of virgin females; nevertheless, they are still tolerated, which so far has been puzzling. Contrasting this general pattern, we have identified a single aberrant colony in which all winged males were attacked and killed by the ergatoid males. A comparative analysis of the morphology and chemical profile of these untypical attacked winged males and the tolerated males from several normal colonies revealed that normal old males are still performing some chemical mimicry to the virgin queens, though less perfect than in their young ages. The anomalous attacked winged males, on the other hand, had a very different odour to the females. Our study thus exemplifies that the analysis of rare malfunctioning can add valuable insight on functioning under normal conditions and allows the conclusion that older winged males from normal colonies of the ant C. obscurior are guarded through an imperfect chemical female mimicry, still close enough to protect against attacks by the wingless fighters yet dissimilar enough not to elicit their sexual interest.}, author = {Cremer, Sylvia and D'Ettorre, Patrizia and Drijfhout, Falko and Sledge, Matthew and Turillazzi, Stefano and Heinze, Jürgen}, issn = {1432-1904}, journal = {Naturwissenschaften}, number = {11}, pages = {1101 -- 1105}, publisher = {Springer Nature}, title = {{Imperfect chemical female mimicry in males of the ant Cardiocondyla obscurior}}, doi = {10.1007/s00114-008-0430-8}, volume = {95}, year = {2008}, } @article{3941, abstract = {All metazoan cells carry transmembrane receptors of the integrin family, which couple the contractile force of the actomyosin cytoskeleton to the extracellular environment. In agreement with this principle, rapidly migrating leukocytes use integrin-mediated adhesion when moving over two-dimensional surfaces. As migration on two-dimensional substrates naturally overemphasizes the role of adhesion, the contribution of integrins during three-dimensional movement of leukocytes within tissues has remained controversial. We studied the interplay between adhesive, contractile and protrusive forces during interstitial leukocyte chemotaxis in vivo and in vitro. We ablated all integrin heterodimers from murine leukocytes, and show here that functional integrins do not contribute to migration in three-dimensional environments. Instead, these cells migrate by the sole force of actin-network expansion, which promotes protrusive flowing of the leading edge. Myosin II-dependent contraction is only required on passage through narrow gaps, where a squeezing contraction of the trailing edge propels the rigid nucleus.}, author = {Lämmermann, Tim and Bader, Bernhard and Monkley, Susan and Worbs, Tim and Wedlich Söldner, Roland and Hirsch, Karin and Keller, Markus and Förster, Reinhold and Critchley, David and Fässler, Reinhard and Sixt, Michael K}, issn = {1476-4687}, journal = {Nature}, number = {7191}, pages = {51 -- 55}, publisher = {Nature Publishing Group}, title = {{Rapid leukocyte migration by integrin-independent flowing and squeezing}}, doi = {10.1038/nature06887}, volume = {453}, year = {2008}, } @article{3939, abstract = {The priming of a T cell results from its physical interaction with a dendritic cell (DC) that presents the cognate antigenic peptide. The success rate of such interactions is extremely low, because the precursor frequency of a naive T cell recognizing a specific antigen is in the range of 1:10(5)-10(6). To make this principle practicable, encounter frequencies between DCs and T cells are maximized within lymph nodes (LNs) that are compact immunological projections of the peripheral tissue they drain. But LNs are more than passive meeting places for DCs that immigrated from the tissue and lymphocytes that recirculated via the blood. The microanatomy of the LN stroma actively organizes the cellular encounters by providing preformed migration tracks that create dynamic but highly ordered movement patterns. LN architecture further acts as a sophisticated filtration system that sieves the incoming interstitial fluid at different levels and guarantees that immunologically relevant antigens are loaded on DCs or B cells while inert substances are channeled back into the blood circulation. This review focuses on the non-hematopoietic infrastructure of the lymph node. We describe the association between fibroblastic reticular cell, conduit, DC, and T cell as the essential functional unit of the T-cell cortex.}, author = {Lämmermann, Tim and Sixt, Michael K}, issn = {1600-065X}, journal = {Immunological Reviews}, number = {1}, pages = {26 -- 43}, publisher = {Wiley-Blackwell}, title = {{The microanatomy of T-cell responses}}, doi = {10.1111/j.1600-065X.2008.00592.x}, volume = {221}, year = {2008}, } @article{3940, abstract = {Until recently little information was available on the molecular details of the extracellular matrix (ECM) of secondary lymphoid tissues. There is now growing evidence that these ECMs are unique structures, combining characteristics of basement membranes and interstitial or fibrillar matrices, resulting in scaffolds that are strong and highly flexible and, in certain secondary lymphoid compartments, also forming conduit networks for rapid fluid transport. This review will address the structural characteristics of the ECM of the murine spleen and its potential role as an organizer of immune cell compartments, with reference to the lymph node where relevant.}, author = {Lokmic, Zerina and Lämmermann, Tim and Sixt, Michael K and Cardell, Susanna and Hallmann, Rupert and Sorokin, Lydia}, issn = {1096-3618}, journal = {Seminars in Immunology}, number = {1}, pages = {4 -- 13}, publisher = {Academic Press}, title = {{The extracellular matrix of the spleen as a potential organizer of immune cell compartments}}, doi = {10.1016/j.smim.2007.12.009}, volume = {20}, year = {2008}, } @article{3906, author = {Cremer, Sylvia and Ugelvig, Line V and Drijfhout, Falko and Schlick Steiner, Birgit and Steiner, Florian and Seifert, Bernhard and Hughes, David and Schulz, Andreas and Petersen, Klaus and Konrad, Heino and Stauffer, Christian and Kiran, Kadri and Espadaler, Xavier and D'Ettorre, Patrizia and Aktaç, Nihat and Eilenberg, Jørgen and Jones, Graeme and Nash, David and Pedersen, Jes and Boomsma, Jacobus}, issn = {1932-6203}, journal = {PLoS One}, number = {12}, publisher = {Public Library of Science}, title = {{The evolution of invasiveness in garden ants}}, doi = {10.1371/journal.pone.0003838}, volume = {3}, year = {2008}, } @inproceedings{3876, abstract = {We consider two-player games played in real time on game structures with clocks and parity objectives. The games are concurrent in that at each turn, both players independently propose a time delay and an action, and the action with the shorter delay is chosen. To prevent a player from winning by blocking time, we restrict each player to strategies that ensure that the player cannot be responsible for causing a zeno run. First, we present an efficient reduction of these games to turn-based (i.e., nonconcurrent) finite-state (i.e., untimed) parity games. The states of the resulting game are pairs of clock regions of the original game. Our reduction improves the best known complexity for solving timed parity games. Moreover, the rich class of algorithms for classical parity games can now be applied to timed parity games. Second, we consider two restricted classes of strategies for the player that represents the controller in a real-time synthesis problem, namely, limit-robust and bounded-robust strategies. Using a limit-robust strategy, the controller cannot choose an exact real-valued time delay but must allow for some nonzero jitter in each of its actions. If there is a given lower bound on the jitter, then the strategy is bounded-robust. We show that exact strategies are more powerful than limit-robust strategies, which are more powerful than bounded-robust strategies for any bound. For both kinds of robust strategies, we present efficient reductions to standard timed automaton games. These reductions provide algorithms for the synthesis of robust real-time controllers.}, author = {Chatterjee, Krishnendu and Henzinger, Thomas A and Prabhu, Vinayak}, booktitle = {Proceedings of the 6th international conference on Formal Modeling and Analysis of Timed Systems}, isbn = {9783540857778}, issn = {1611-3349}, location = {Saint Malo, France}, pages = {124 -- 140}, publisher = {Springer Nature}, title = {{Timed parity games: complexity and robustness}}, doi = {10.1007/978-3-540-85778-5_10}, volume = {5215}, year = {2008}, }