TY - JOUR AB - Pancreas development involves a coordinated process in which an early phase of cell segregation is followed by a longer phase of lineage restriction, expansion, and tissue remodeling. By combining clonal tracing and whole-mount reconstruction with proliferation kinetics and single-cell transcriptional profiling, we define the functional basis of pancreas morphogenesis. We show that the large-scale organization of mouse pancreas can be traced to the activity of self-renewing precursors positioned at the termini of growing ducts, which act collectively to drive serial rounds of stochastic ductal bifurcation balanced by termination. During this phase of branching morphogenesis, multipotent precursors become progressively fate-restricted, giving rise to self-renewing acinar-committed precursors that are conveyed with growing ducts, as well as ductal progenitors that expand the trailing ducts and give rise to delaminating endocrine cells. These findings define quantitatively how the functional behavior and lineage progression of precursor pools determine the large-scale patterning of pancreatic sub-compartments. AU - Sznurkowska, Magdalena AU - Hannezo, Edouard B AU - Azzarelli, Roberta AU - Rulands, Steffen AU - Nestorowa, Sonia AU - Hindley, Christopher AU - Nichols, Jennifer AU - Göttgens, Berthold AU - Huch, Meritxell AU - Philpott, Anna AU - Simons, Benjamin ID - 132 IS - 3 JF - Developmental Cell TI - Defining lineage potential and fate behavior of precursors during pancreas development VL - 46 ER - TY - JOUR AB - Seeds derive from ovules upon fertilization and therefore the total number of ovules determines the final seed yield, a fundamental trait in crop plants. Among the factors that co-ordinate the process of ovule formation, the transcription factors CUP-SHAPED COTYLEDON 1 (CUC1) and CUC2 and the hormone cytokinin (CK) have a particularly prominent role. Indeed, the absence of both CUC1 and CUC2 causes a severe reduction in ovule number, a phenotype that can be rescued by CK treatment. In this study, we combined CK quantification with an integrative genome-wide target identification approach to select Arabidopsis genes regulated by CUCs that are also involved in CK metabolism. We focused our attention on the functional characterization of UDP-GLUCOSYL TRANSFERASE 85A3 (UGT85A3) and UGT73C1, which are up-regulated in the absence of CUC1 and CUC2 and encode enzymes able to catalyse CK inactivation by O-glucosylation. Our results demonstrate a role for these UGTs as a link between CUCs and CK homeostasis, and highlight the importance of CUCs and CKs in the determination of seed yield. AU - Cucinotta, Mara AU - Manrique, Silvia AU - Cuesta, Candela AU - Benková, Eva AU - Novák, Ondřej AU - Colombo, Lucia ID - 42 IS - 21 JF - Journal of Experimental Botany TI - Cup-shaped Cotyledon1 (CUC1) and CU2 regulate cytokinin homeostasis to determine ovule number in arabidopsis VL - 69 ER - TY - JOUR AB - Isoprenoid cytokinins play a number of crucial roles in the regulation of plant growth and development. To study cytokinin receptor properties in plants, we designed and prepared fluorescent derivatives of 6-[(3-methylbut-2-en-1-yl)amino]purine (N6-isopentenyladenine, iP) with several fluorescent labels attached to the C2 or N9 atom of the purine moiety via a 2- or 6-carbon linker. The fluorescent labels included dansyl (DS), fluorescein (FC), 7-nitrobenzofurazan (NBD), rhodamine B (RhoB), coumarin (Cou), 7-(diethylamino)coumarin (DEAC) and cyanine 5 dye (Cy5). All prepared compounds were screened for affinity for the Arabidopsis thaliana cytokinin receptor (CRE1/AHK4). Although the attachment of the fluorescent labels to iP via the linkers mostly disrupted binding to the receptor, several fluorescent derivatives interacted well. For this reason, three derivatives, two rhodamine B and one 4-chloro-7-nitrobenzofurazan labeled iP were tested for their interaction with CRE1/AHK4 and Zea mays cytokinin receptors in detail. We further showed that the three derivatives were able to activate transcription of cytokinin response regulator ARR5 in Arabidopsis seedlings. The activity of fluorescently labeled cytokinins was compared with corresponding 6-dimethylaminopurine fluorescently labeled negative controls. Selected rhodamine B C2-labeled compounds 17, 18 and 4-chloro-7-nitrobenzofurazan N9-labeled compound 28 and their respective negative controls (19, 20 and 29, respectively) were used for in planta staining experiments in Arabidopsis thaliana cell suspension culture using live cell confocal microscopy. AU - Kubiasová, Karolina AU - Mik, Václav AU - Nisler, Jaroslav AU - Hönig, Martin AU - Husičková, Alexandra AU - Spíchal, Lukáš AU - Pěkná, Zuzana AU - Šamajová, Olga AU - Doležal, Karel AU - Plíhal, Ondřej AU - Benková, Eva AU - Strnad, Miroslav AU - Plíhalová, Lucie ID - 407 JF - Phytochemistry TI - Design, synthesis and perception of fluorescently labeled isoprenoid cytokinins VL - 150 ER - TY - JOUR AB - We analyze a disordered central spin model, where a central spin interacts equally with each spin in a periodic one-dimensional (1D) random-field Heisenberg chain. If the Heisenberg chain is initially in the many-body localized (MBL) phase, we find that the coupling to the central spin suffices to delocalize the chain for a substantial range of coupling strengths. We calculate the phase diagram of the model and identify the phase boundary between the MBL and ergodic phase. Within the localized phase, the central spin significantly enhances the rate of the logarithmic entanglement growth and its saturation value. We attribute the increase in entanglement entropy to a nonextensive enhancement of magnetization fluctuations induced by the central spin. Finally, we demonstrate that correlation functions of the central spin can be utilized to distinguish between MBL and ergodic phases of the 1D chain. Hence, we propose the use of a central spin as a possible experimental probe to identify the MBL phase. AU - Hetterich, Daniel AU - Yao, Norman AU - Serbyn, Maksym AU - Pollmann, Frank AU - Trauzettel, Björn ID - 46 IS - 16 JF - Physical Review B TI - Detection and characterization of many-body localization in central spin models VL - 98 ER - TY - JOUR AB - Migrating cells penetrate tissue barriers during development, inflammatory responses, and tumor metastasis. We study if migration in vivo in such three-dimensionally confined environments requires changes in the mechanical properties of the surrounding cells using embryonic Drosophila melanogaster hemocytes, also called macrophages, as a model. We find that macrophage invasion into the germband through transient separation of the apposing ectoderm and mesoderm requires cell deformations and reductions in apical tension in the ectoderm. Interestingly, the genetic pathway governing these mechanical shifts acts downstream of the only known tumor necrosis factor superfamily member in Drosophila, Eiger, and its receptor, Grindelwald. Eiger-Grindelwald signaling reduces levels of active Myosin in the germband ectodermal cortex through the localization of a Crumbs complex component, Patj (Pals-1-associated tight junction protein). We therefore elucidate a distinct molecular pathway that controls tissue tension and demonstrate the importance of such regulation for invasive migration in vivo. AU - Ratheesh, Aparna AU - Biebl, Julia AU - Smutny, Michael AU - Veselá, Jana AU - Papusheva, Ekaterina AU - Krens, Gabriel AU - Kaufmann, Walter AU - György, Attila AU - Casano, Alessandra M AU - Siekhaus, Daria E ID - 308 IS - 3 JF - Developmental Cell TI - Drosophila TNF modulates tissue tension in the embryo to facilitate macrophage invasive migration VL - 45 ER - TY - JOUR AB - Creeping flow of polymeric fluid without inertia exhibits elastic instabilities and elastic turbulence accompanied by drag enhancement due to elastic stress produced by flow-stretched polymers. However, in inertia-dominated flow at high Re and low fluid elasticity El, a reduction in turbulent frictional drag is caused by an intricate competition between inertial and elastic stresses. Here we explore the effect of inertia on the stability of viscoelastic flow in a broad range of control parameters El and (Re,Wi). We present the stability diagram of observed flow regimes in Wi-Re coordinates and find that the instabilities' onsets show an unexpectedly nonmonotonic dependence on El. Further, three distinct regions in the diagram are identified based on El. Strikingly, for high-elasticity fluids we discover a complete relaminarization of flow at Reynolds number in the range of 1 to 10, different from a well-known turbulent drag reduction. These counterintuitive effects may be explained by a finite polymer extensibility and a suppression of vorticity at high Wi. Our results call for further theoretical and numerical development to uncover the role of inertial effect on elastic turbulence in a viscoelastic flow. AU - Varshney, Atul AU - Steinberg, Victor ID - 17 IS - 10 JF - Physical Review Fluids TI - Drag enhancement and drag reduction in viscoelastic flow VL - 3 ER - TY - JOUR AB - Although cells respond specifically to environments, how environmental identity is encoded intracellularly is not understood. Here, we study this organization of information in budding yeast by estimating the mutual information between environmental transitions and the dynamics of nuclear translocation for 10 transcription factors. Our method of estimation is general, scalable, and based on decoding from single cells. The dynamics of the transcription factors are necessary to encode the highest amounts of extracellular information, and we show that information is transduced through two channels: Generalists (Msn2/4, Tod6 and Dot6, Maf1, and Sfp1) can encode the nature of multiple stresses, but only if stress is high; specialists (Hog1, Yap1, and Mig1/2) encode one particular stress, but do so more quickly and for a wider range of magnitudes. In particular, Dot6 encodes almost as much information as Msn2, the master regulator of the environmental stress response. Each transcription factor reports differently, and it is only their collective behavior that distinguishes between multiple environmental states. Changes in the dynamics of the localization of transcription factors thus constitute a precise, distributed internal representation of extracellular change. We predict that such multidimensional representations are common in cellular decision-making. AU - Granados, Alejandro AU - Pietsch, Julian AU - Cepeda Humerez, Sarah A AU - Farquhar, Isebail AU - Tkacik, Gasper AU - Swain, Peter ID - 281 IS - 23 JF - PNAS TI - Distributed and dynamic intracellular organization of extracellular information VL - 115 ER - TY - JOUR AB - Clathrin-mediated endocytosis requires the coordinated assembly of various endocytic proteins and lipids at the plasma membrane. Accumulating evidence demonstrates a crucial role for phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) in endocytosis, but specific roles for PtdIns(4)P other than as the biosynthetic precursor of PtdIns(4,5)P2 have not been clarified. In this study we investigated the role of PtdIns(4)P or PtdIns(4,5)P2 in receptor-mediated endocytosis through the construction of temperature-sensitive (ts) mutants for the PI 4-kinases Stt4p and Pik1p and the PtdIns(4) 5-kinase Mss4p. Quantitative analyses of endocytosis revealed that both the stt4(ts)pik1(ts) and mss4(ts) mutants have a severe defect in endocytic internalization. Live-cell imaging of endocytic protein dynamics in stt4(ts)pik1(ts) and mss4(ts) mutants revealed that PtdIns(4)P is required for the recruitment of the alpha-factor receptor Ste2p to clathrin-coated pits whereas PtdIns(4,5)P2 is required for membrane internalization. We also found that the localization to endocytic sites of the ENTH/ANTH domain-bearing clathrin adaptors, Ent1p/Ent2p and Yap1801p/Yap1802p, is significantly impaired in the stt4(ts)pik1(ts) mutant, but not in the mss4(ts) mutant. These results suggest distinct roles in successive steps for PtdIns(4)P and PtdIns(4,5)P2 during receptor-mediated endocytosis. AU - Yamamoto, Wataru AU - Wada, Suguru AU - Nagano, Makoto AU - Aoshima, Kaito AU - Siekhaus, Daria E AU - Toshima, Junko AU - Toshima, Jiro ID - 620 IS - 1 JF - Journal of Cell Science TI - Distinct roles for plasma membrane PtdIns 4 P and PtdIns 4 5 P2 during yeast receptor mediated endocytosis VL - 131 ER - TY - CONF AB - We describe a new algorithm for the parametric identification problem for signal temporal logic (STL), stated as follows. Given a densetime real-valued signal w and a parameterized temporal logic formula φ, compute the subset of the parameter space that renders the formula satisfied by the signal. Unlike previous solutions, which were based on search in the parameter space or quantifier elimination, our procedure works recursively on φ and computes the evolution over time of the set of valid parameter assignments. This procedure is similar to that of monitoring or computing the robustness of φ relative to w. Our implementation and experiments demonstrate that this approach can work well in practice. AU - Bakhirkin, Alexey AU - Ferrere, Thomas AU - Maler, Oded ID - 182 SN - 978-1-4503-5642-8 T2 - Proceedings of the 21st International Conference on Hybrid Systems TI - Efficient parametric identification for STL ER - TY - CONF AB - Vector Addition Systems with States (VASS) provide a well-known and fundamental model for the analysis of concurrent processes, parameterized systems, and are also used as abstract models of programs in resource bound analysis. In this paper we study the problem of obtaining asymptotic bounds on the termination time of a given VASS. In particular, we focus on the practically important case of obtaining polynomial bounds on termination time. Our main contributions are as follows: First, we present a polynomial-time algorithm for deciding whether a given VASS has a linear asymptotic complexity. We also show that if the complexity of a VASS is not linear, it is at least quadratic. Second, we classify VASS according to quantitative properties of their cycles. We show that certain singularities in these properties are the key reason for non-polynomial asymptotic complexity of VASS. In absence of singularities, we show that the asymptotic complexity is always polynomial and of the form Θ(nk), for some integer k d, where d is the dimension of the VASS. We present a polynomial-time algorithm computing the optimal k. For general VASS, the same algorithm, which is based on a complete technique for the construction of ranking functions in VASS, produces a valid lower bound, i.e., a k such that the termination complexity is (nk). Our results are based on new insights into the geometry of VASS dynamics, which hold the potential for further applicability to VASS analysis. AU - Brázdil, Tomáš AU - Chatterjee, Krishnendu AU - Kučera, Antonín AU - Novotny, Petr AU - Velan, Dominik AU - Zuleger, Florian ID - 143 SN - 978-1-4503-5583-4 TI - Efficient algorithms for asymptotic bounds on termination time in VASS VL - F138033 ER -