@article{2442, abstract = {In a new study published in this issue of Developmental Cell, Krouk et al. reveal a surprising mechanism by which plant root systems adapt their architecture for soil exploitation. The dual transporter NRT1.1 uses both nitrate and the plant hormone auxin as substrates, enabling soil nitrate availability to regulate auxin-driven lateral root development.}, author = {Beeckman, Tom and Friml, Jirí}, journal = {Developmental Cell}, number = {6}, pages = {877 -- 878}, publisher = {Cell Press}, title = {{Nitrate Contra Auxin: Nutrient Sensing by roots}}, doi = {10.1016/j.devcel.2010.05.020}, volume = {18}, year = {2010}, } @article{2503, abstract = {Epilepsy is a devastating and poorly understood disease. Mutations in a secreted neuronal protein, leucine-rich glioma inactivated 1 (LGI1), were reported in patients with an inherited form of human epilepsy, autosomal dominant partial epilepsy with auditory features (ADPEAF). Here, we report an essential role of LGI1 as an antiepileptogenic ligand. We find that loss of LGI1 in mice (LGI1-/-) causes lethal epilepsy, which is specifically rescued by the neuronal expression of LGI1 transgene, but not LGI3. Moreover, heterozygous mice for the LGI1 mutation (LGI1+/-) show lowered seizure thresholds. Extracellularly secreted LGI1 links two epilepsy-related receptors, ADAM22 and ADAM23, in the brain and organizes a transsynaptic protein complex that includes presynaptic potassium channels and postsynaptic AMPA receptor scaffolds. A lack of LGI1 disrupts this synaptic protein connection and selectively reduces AMPA receptor-mediated synaptic transmission in the hippocampus. Thus, LGI1 may serve as a major determinant of brain excitation, and the LGI1 gene-targeted mouse provides a good model for human epilepsy.}, author = {Fukata, Yuko and Lovero, Kathryn L and Iwanaga, Tsuyoshi and Watanabe, Atsushi and Yokoi, Norihiko and Tabuchi, Katsuhiko and Ryuichi Shigemoto and Nicoll, Roger A and Fukata, Masaki}, journal = {PNAS}, number = {8}, pages = {3799 -- 3804}, publisher = {National Academy of Sciences}, title = {{Disruption of LGI1-linked synaptic complex causes abnormal synaptic transmission and epilepsy}}, doi = {10.1073/pnas.0914537107}, volume = {107}, year = {2010}, } @article{2504, abstract = {We present a method for immunolabeling of multiple species of membrane proteins with high spatial resolution. It allows differentiation of equally sized very small markers with different chemical compositions, which leads to high labeling efficiency and reduces steric hindrance of closely spaced immunolabeled biomolecules. Markers such as CdSe/ZnS semiconductor quantum dots and colloidal gold particles are distinguished by differential contrast in high-angle annular detector dark-field STEM mode or by EDX microanalysis of their elemental contents. This method was tested by observation of labeled AMPA- and NMDA-type glutamate receptors on sodium-dodecyl-sulfate-digested replica prepared from rat hippocampus. To improve particle visibility and detectability, the replica films were made exclusively with carbon to avoid the high background of conventional platinum/carbon replica. Extension of the method is suggested by detection of 1.4 nm nanogold particles and its potential application in the biological imaging research.}, author = {Loukanov, Alexandre R and Kamasawa, Naomi and Danev, Radostin S and Ryuichi Shigemoto and Nagayama, Kuniaki}, journal = {Ultramicroscopy}, number = {4}, pages = {366 -- 374}, publisher = {Elsevier}, title = {{Immunolocalization of multiple membrane proteins on a carbon replica with STEM and EDX}}, doi = {10.1016/j.ultramic.2010.01.016}, volume = {110}, year = {2010}, } @article{2505, abstract = {Cbln1, secreted from cerebellar granule cells, and the orphan glutamate receptor 52 (GluD2), expressed by Purkinje cells, are essential for synapse integrity between these neurons in adult mice. Nevertheless, no endogenous binding partners for these molecules have been identified. We found that Cblnl binds directly to the N-terminal domain of GluD2. GluD2 expression by postsynaptic cells, combined with exogenously applied Cbln1, was necessary and sufficient to induce new synapses in vitro and in the adult cerebellum in vivo. Further, beads coated with recombinant Cbln1 directly induced presynaptic differentiation and indirectly caused clustering of postsynaptic molecules via GluD2. These results indicate that the Cbln1-GluD2 complex is a unique synapse organizer that acts bidirectionally on both pre- and postsynaptic components.}, author = {Matsuda, Keiko and Miura, Eriko and Miyazaki, Taisuke and Kakegawa, Wataru and Emi, Kyoichi and Narumi, Sakae and Fukazawa, Yugo and Ito-lshida, Aya and Kondo, Tetsuro and Ryuichi Shigemoto and Watanabe, Masahiko and Yuzaki, Michisuke}, journal = {Science}, number = {5976}, pages = {363 -- 368}, publisher = {American Association for the Advancement of Science}, title = {{Cbln1 is a ligand for an orphan glutamate receptor δ2, a bidirectional synapse organizer}}, doi = {10.1126/science.1185152}, volume = {328}, year = {2010}, } @article{2506, abstract = {Subepithelial fibroblasts of the intestinal villi, which form a contractile cellular network beneath the epithelium, are in close contact with epithelial cells, nerve varicosities, capillaries, smooth muscles and immune cells, and secrete extracellular matrix molecules, growth factors and cytokines, etc. Cultured subepithelial fibroblasts of the rat duodenal villi display various receptors such as endothelins, ATP, substance-P and bradykinin, and release ATP in response to mechanical stimulation. In this study, the presence of functional NK1 receptors (NK1R) was pharmacologically confirmed in primary culture by Ca 2+ measurement, and the effects of substance-P were measured in an acute preparation of epithelium-free duodenal villi from 2- to 3-week-old rats using a two-photon laser microscope. Substance-P elicited an increase in the intracellular Ca 2+ concentration and contraction of the subepithelial fibroblasts in culture and the isolated villi. The localization of NK1R and substance-P in the villi was examined by light and electron microscopic immunohistochemistry. NK1R-like immunoreactivity was intensely localized on the plasma membrane of villous subepithelial fibroblasts in 10-day- to 4-week-old rats and mice and was decreased or absent in adulthood. The pericryptal fibroblasts of the small and large intestine were NK1R immuno-negative. These villous subepithelial fibroblasts form synapse-like structures with both substance-P-immunopositive and -immunonegative nerve varicosities. Here, we propose that the mutual interaction between villous subepithelial fibroblasts and afferent neurons via substance-P and ATP plays important roles in the maturation of the structure and function of the small intestine.}, author = {Furuya, Sonoko and Furuya, Kishio and Ryuichi Shigemoto and Sokabe, Masahiro}, journal = {Cell and Tissue Research}, number = {2}, pages = {243 -- 259}, publisher = {Springer}, title = {{Localization of NK1 receptors and roles of substance-P in subepithelial fibroblasts of rat intestinal villi}}, doi = {10.1007/s00441-010-1056-7}, volume = {342}, year = {2010}, } @article{2507, abstract = {T-type calcium channels play a pivotal role in regulating neural membrane excitability in the nervous system. However, the precise subcellular distributions of T-type channel subunits and their implication for membrane excitability are not well understood. Here we investigated the subcellular distribution of the α1G subunit of the calcium channel which is expressed highly in the mouse dorsal lateral geniculate nucleus (dLGN). Light microscopic analysis demonstrated that dLGN exhibits intense immunoperoxidase reactivity for the α1G subunit. Electron microscopic observation showed that the labeling was present in both the relay cells and interneurons and was found in the somatodendritic, but not axonal, domains of these cells. Most of the immunogold particles for the α1G subunit were either associated with the plasma membrane or the intracellular membranes. Reconstruction analysis of serial electron microscopic images revealed that the intensity of the intracellular labeling exhibited a gradient such that the labeling density was higher in the proximal dendrite and progressively decreased towards the distal dendrite. In contrast, the plasma membrane-associated particles were distributed with a uniform density over the somatodendritic surface of dLGN cells. The labeling density in the relay cell plasma membrane was about 3-fold higher than that of the interneurons. These results provide ultrastructural evidence for cell-type-specific expression levels and for uniform expression density of the α1G subunit over the plasma membrane of dLGN cells.}, author = {Parajuli, Laxmi K and Fukazawa, Yugo and Watanabe, Masahiko and Ryuichi Shigemoto}, journal = {Journal of Comparative Neurology}, number = {21}, pages = {4362 -- 4374}, publisher = {Wiley-Blackwell}, title = {{Subcellular distribution of α1G subunit of T-type calcium channel in the mouse dorsal lateral geniculate nucleus}}, doi = {10.1002/cne.22461}, volume = {518}, year = {2010}, } @article{2508, abstract = {The activity patterns of subthalamic nucleus (STN) neurons are intimately linked to motor function and dysfunction and arise through the complex interaction of intrinsic properties and inhibitory and excitatory synaptic inputs. In many neurons, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play key roles in intrinsic excitability and synaptic integration both under normal conditions and in disease states. However, in STN neurons, which strongly express HCN channels, their roles remain relatively obscure. To address this deficit, complementary molecular and cellular electrophysiological, imaging, and computational approaches were applied to the rat STN. Molecular profiling demonstrated that individual STN neurons express mRNA encoding several HCN subunits, with HCN2 and 3 being the most abundant. Light and electron microscopic analysis showed that HCN2 subunits are strongly expressed and distributed throughout the somatodendritic plasma membrane. Voltage-, current-, and dynamic-clamp analysis, two-photon Ca 2+ imaging, and computational modeling revealed that HCN channels are activated by GABA A receptor-mediated inputs and thus limit synaptic hyperpolarization and deinactivation of low-voltage-activated Ca 2+ channels. Although HCN channels also limited the temporal summation of EPSPs, generated through two-photon uncaging of glutamate, this action was largely shunted by GABAergic inhibition that was necessary for HCN channel activation. Together the data demonstrate that HCN channels in STN neurons selectively counteract GABA A receptor-mediated inhibition arising from the globus pallidus and thus promote single-spike activity rather than rebound burst firing. }, author = {Atherton, Jeremy F and Kitano, Katsunori and Baufreton, Jérôme and Fan, Kai and Wokosin, David L and Tkatch, Tatiana and Ryuichi Shigemoto and Surmeier, James D and Bevan, Mark D}, journal = {Journal of Neuroscience}, number = {47}, pages = {16025 -- 16040}, publisher = {Society for Neuroscience}, title = {{Selective participation of somatodendritic HCN channels in inhibitory but not excitatory synaptic integration in neurons of the subthalamic nucleus}}, doi = {10.1523/JNEUROSCI.3898-10.2010}, volume = {30}, year = {2010}, } @article{2509, abstract = {Hippocampal CA1 pyramidal cells, which receive γ-aminobutyric acid (GABA)ergic input from at least 18 types of presynaptic neuron, express 14 subunits of the pentameric GABAA receptor. The relative contribution of any subunit to synaptic and extrasynaptic receptors influences the dynamics of GABA and drug actions. Synaptic receptors mediate phasic GABA-evoked conductance and extrasynaptic receptors contribute to a tonic conductance. We used freeze-fracture replica-immunogold labelling, a sensitive quantitative immunocytochemical method, to detect synaptic and extrasynaptic pools of the alpha1, alpha2 and beta3 subunits. Antibodies to the cytoplasmic loop of the subunits showed immunogold particles concentrated on distinct clusters of intramembrane particles (IMPs) on the cytoplasmic face of the plasma membrane on the somata, dendrites and axon initial segments, with an abrupt decrease in labelling at the edge of the IMP cluster. Neuroligin-2, a GABAergic synapse-specific adhesion molecule, co-labels all beta3 subunit-rich IMP clusters, therefore we considered them synapses. Double-labelling for two subunits showed that virtually all somatic synapses contain the alpha1, alpha2 and beta3 subunits. The extrasynaptic plasma membrane of the somata, dendrites and dendritic spines showed low-density immunolabelling. Synaptic labelling densities on somata for the alpha1, alpha2 and beta3 subunits were 78-132, 94 and 79 times higher than on the extrasynaptic membranes, respectively. As GABAergic synapses occupy 0.72% of the soma surface, the fraction of synaptic labelling was 33-48 (alpha1), 40 (alpha2) and 36 (beta3)% of the total somatic surface immunolabelling. Assuming similar antibody access to all receptors, about 60% of these subunits are in extrasynaptic receptors.}, author = {Kasugai, Yu and Swinny, Jerome D and Roberts, John D and Dalezios, Yannis and Fukazawa, Yugo and Sieghart, Werner C and Ryuichi Shigemoto and Somogyi, Péter}, journal = {European Journal of Neuroscience}, number = {11}, pages = {1868 -- 1888}, publisher = {Wiley-Blackwell}, title = {{Quantitative localisation of synaptic and extrasynaptic GABAA receptor subunits on hippocampal pyramidal cells by freeze-fracture replica immunolabelling}}, doi = {10.1111/j.1460-9568.2010.07473.x}, volume = {32}, year = {2010}, } @article{2510, abstract = {Neurons in the laterocapsular division of the central nucleus of the amygdala (CeC), which is known as the "nociceptive amygdala," receive glutamatergic inputs from the parabrachial nucleus (PB) and the basolateral nucleus of amygdala (BLA), which convey nociceptive information from the dorsal horn of the spinal cord and polymodal information from the thalamus and cortex, respectively. Here, we examined the ultrastructural properties of PB- and BLA-CeC synapses identified with EGFP-expressing lentivirus in rats. In addition, the density of synaptic AMPA receptors (AMPARs) on CeC neurons was studied by using highly sensitive SDS-digested freeze-fracture replica labeling (SDS-FRL). Afferents from the PB made asymmetrical synapses mainly on dendritic shafts (88%), whereas those from the BLA were on dendritic spines (81%). PB-CeC synapses in dendritic shafts were significantly larger (median 0.072 μm 2) than BLA-CeC synapses in spines (median 0.058 μm 2; P = 0.02). The dendritic shafts that made synapses with PB fibers were also significantly larger than those that made synapses with BLA fibers, indicating that the PB fibers make synapses on more proximal parts of dendrites than the BLA fibers. SDS-FRL revealed that almost all excitatory postsynaptic sites have AMPARs in the CeC. The density of AMPAR-specific gold particles in individual synapses was significantly higher in spine synapses (median 510 particles/μm 2) than in shaft synapses (median 427 particles/μm 2; P = 0.01). These results suggest that distinct synaptic impacts from PB- and BLA-CeC pathways contribute to the integration of nociceptive and polymodal information in the CeC.}, author = {Dong, Yu-Lin and Fukazawa, Yugo and Wang, Wen and Kamasawa, Naomi and Ryuichi Shigemoto}, journal = {Journal of Comparative Neurology}, number = {23}, pages = {4771 -- 4791}, publisher = {Wiley-Blackwell}, title = {{Differential postsynaptic compartments in the laterocapsular division of the central nucleus of amygdala for afferents from the parabrachial nucleus and the basolateral nucleus in the rat}}, doi = {10.1002/cne.22487}, volume = {518}, year = {2010}, } @article{2701, abstract = {We consider N × N Hermitian random matrices with independent identically distributed entries (Wigner matrices). The matrices are normalized so that the average spacing between consecutive eigenvalues is of order 1/ N. Under suitable assumptions on the distribution of the single matrix element, we first prove that, away from the spectral edges, the empirical density of eigenvalues concentrates around the Wigner semicircle law on energy scales η ≫ N -1. This result establishes the semicircle law on the optimal scale and it removes a logarithmic factor from our previous result [6]. We then show a Wegner estimate, i.e., that the averaged density of states is bounded. Finally, we prove that the eigenvalues of a Wigner matrix repel each other, in agreement with the universality conjecture.}, author = {László Erdös and Schlein, Benjamin and Yau, Horng-Tzer}, journal = {International Mathematics Research Notices}, number = {3}, pages = {436 -- 479}, publisher = {Oxford University Press}, title = {{Wegner estimate and level repulsion for Wigner random matrices}}, doi = {10.1093/imrn/rnp136}, year = {2010}, } @article{2704, abstract = {Consider a system of N bosons in three dimensions interacting via a repulsive short range pair potential N2V(N(xi-xj)), where x = (x1, ..., xN) denotes the positions of the particles. Let HN, denote the Hamiltonian of the system and let ψN,t be the solution to the Schrödinger equation. Suppose that the initial data ψN,0 satisfies the energy condition 〈 ψ N,0,Hk N ψN,0〉 ≤ CkNk for k =1, 2, ....We also assume that the k-particle density matrices of the initial state are asymptotically factorized as N →∞1. We prove that the k-particle density matrices of ψN,t are also asymptotically factorized and the one particle orbital wave function solves the Gross-Pitaevskii equation, a cubic nonlinear Schrödinger equation with the coupling constant given by the scattering length of the potential V. We also prove the same conclusion if the energy condition holds only for k=1 but the factorization of ψN,0 is assumed in a stronger sense.}, author = {László Erdös and Schlein, Benjamin and Yau, Horng-Tzer}, journal = {Annals of Mathematics}, number = {1}, pages = {291 -- 370}, publisher = {Princeton University Press}, title = {{Derivation of the Gross-Pitaevskii equation for the dynamics of Bose-Einstein condensate}}, doi = {10.4007/annals.2010.172.291}, volume = {172}, year = {2010}, } @article{2756, abstract = {We consider a large atom with nuclear charge Z described by non-relativistic quantum mechanics with classical or quantized electromagnetic field. We prove that the absolute ground state energy, allowing for minimizing over all possible self-generated electromagnetic fields, is given by the non-magnetic Thomas-Fermi theory to leading order in the simultaneous Z → ∞, α → 0 limit if Zα2 ≤ κ for some universal κ, where α is the fine structure constant.}, author = {László Erdös and Solovej, Jan P}, journal = {Communications in Mathematical Physics}, number = {1}, pages = {229 -- 249}, publisher = {Springer}, title = {{Ground state energy of large atoms in a self-generated magnetic field}}, doi = {10.1007/s00220-009-0869-2}, volume = {294}, year = {2010}, } @article{2761, abstract = {We consider N × N Hermitian random matrices with independent identically distributed entries (Wigner matrices). We assume that the distribution of the entries have a Gaussian component with variance N 3/4+β for some positive β > 0. We prove that the local eigenvalue statistics follows the universal Dyson sine kernel.}, author = {László Erdös and Ramírez, José A and Schlein, Benjamin and Yau, Horng-Tzer}, journal = {Electronic Journal of Probability}, number = {18}, pages = {526 -- 603}, publisher = {Institute of Mathematical Statistics}, title = {{Universality of sine-kernel for Wigner matrices with a small Gaussian perturbation}}, doi = {10.1214/EJP.v15-768}, volume = {15}, year = {2010}, } @article{2762, abstract = {We consider N ×N Hermitian Wigner random matrices H where the probabilitydensity for each matrix element is given by the density v(x)=e-U(x). We prove that the eigenvalue statistics in the bulk are given by the Dyson sine kernel provided that U ∈ C 6(R{double-struck}) with at most polynomially growing derivatives and v(x)≤C e-c(x) for x large. The proof is based upon an approximate time reversal of the Dyson Brownian motion combined with the convergence of the eigenvalue density to the Wigner semicircle law on short scales.}, author = {László Erdös and Ramírez, José A and Yau, Horng-Tzer and Péché, Sandrine and Schlein, Benjamin}, journal = {Communications on Pure and Applied Mathematics}, number = {7}, pages = {895 -- 925}, publisher = {Wiley-Blackwell}, title = {{Bulk universality for Wigner matrices}}, doi = {10.1002/cpa.20317}, volume = {63}, year = {2010}, } @article{2763, abstract = {In this paper, we consider the ensemble of n×n Wigner Hermitian matrices H = (hℓk)1≤ℓ,k≤n that generalize the Gaussian unitary ensemble (GUE). The matrix elements hℓk = h̄ℓk are given by hℓk = n ?1/2(xℓk + √?1yℓk), where xℓk, yℓk for 1 ≤ ℓ < k ≤ n are i.i.d. random variables with mean zero and variance 1/2, yℓ ℓ = 0 and xℓ ℓ have mean zero and variance 1. We assume the distribution of xℓk, yℓk to have subexponential decay. In [3], four of the authors recently established that the gap distribution and averaged k-point correlation of these matrices were universal (and in particular, agreed with those for GUE) assuming additional regularity hypotheses on the xℓk, yℓk. In [7], the other two authors, using a different method, established the same conclusion assuming instead some moment and support conditions on the xℓk, yℓk. In this short note we observe that the arguments of [3] and [7] can be combined to establish universality of the gap distribution and averaged k-point correlations for all Wigner matrices (with subexponentially decaying entries), with no extra assumptions.}, author = {László Erdös and Ramírez, José A and Schlein, Benjamin and Tao, Terence and Van, Vu and Yau, Horng-Tzer}, journal = {Mathematical Research Letters}, number = {4}, pages = {667 -- 674}, publisher = {International Press}, title = {{Bulk universality for Wigner Hermitian matrices with subexponential decay}}, volume = {17}, year = {2010}, } @article{2798, abstract = {Flows through pipes and channels are the most common means to transport fluids in practical applications and equally occur in numerous natural systems. In general, the transfer of fluids is energetically far more efficient if the motion is smooth and laminar because the friction losses are lower. However, even at moderate velocities pipe and channel flows are sensitive to minute disturbances, and in practice most flows are turbulent. Investigating the motion and spatial distribution of vortices, we uncovered an amplification mechanism that constantly feeds energy from the mean shear into turbulent eddies. At intermediate flow rates, a simple control mechanism suffices to intercept this energy transfer by reducing inflection points in the velocity profile. When activated, an immediate collapse of turbulence is observed, and the flow relaminarizes.}, author = {Björn Hof and de Lózar, Alberto and Avila, Marc and Xiaoyun Tu and Schneider, Tobias M}, journal = {Science}, number = {5972}, pages = {1491 -- 1494}, publisher = {American Association for the Advancement of Science}, title = {{Eliminating turbulence in spatially intermittent flows}}, doi = {10.1126/science.1186091}, volume = {327}, year = {2010}, } @article{2870, abstract = {Dark-grown dicotyledonous seedlings form a hook-like structure at the top of the hypocotyl, which is controlled by the hormones auxin and ethylene. Hook formation is dependent on an auxin signal gradient, whereas hook exaggeration is part of the triple response provoked by ethylene in dark-grown Arabidopsis seedlings. Several other hormones and light are also known to be involved in hook development, but the molecular mechanisms that lead to the initial installation of an auxin gradient are still poorly understood. In this study, we aimed to unravel the cross-talk between auxin and ethylene in the apical hook. Auxin measurements, the expression pattern of the auxin reporter DR5::GUS and the localization of auxin biosynthesis enzymes and influx carriers collectively indicate the necessity for auxin biosynthesis and efficient auxin translocation from the cotyledons and meristem into the hypocotyl in order to support proper hook development. Auxin accumulation in the meristem and cotyledons and in the hypocotyl is increased ∼2-fold upon treatment with ethylene. In addition, a strong ethylene signal leads to enhanced auxin biosynthesis at the inner side of the hook. Finally, mutant analysis demonstrates that the auxin influx carrier LAX3 is indispensable for proper hook formation, whereas the auxin influx carrier AUX1 is involved in the hook exaggeration phenotype induced by ethylene.}, author = {Vandenbussche, Filip and Petrášek, Jan and Žádníková, Petra and Hoyerová, Klára and Pešek, Bedřich and Raz, Vered and Swarup, Ranjan and Bennett, Malcolm and Zažímalová, Eva and Eva Benková and Van Der Straeten, Dominique}, journal = {Development}, number = {4}, pages = {597 -- 606}, publisher = {Company of Biologists}, title = {{The auxin influx carriers AUX1 and LAX3 are involved in auxin-ethylene interactions during apical hook development in Arabidopsis thaliana seedlings}}, doi = {10.1242/dev.040790}, volume = {137}, year = {2010}, } @article{2872, abstract = {Unlike locomotive organisms capable of actively approaching essential resources, sessile plants must efficiently exploit their habitat for water and nutrients. This involves root-mediated underground interactions allowing plants to adapt to soils of diverse qualities. The root system of plants is a dynamic structure that modulates primary root growth and root branching by continuous integration of environmental inputs, such as nutrition availability, soil aeration, humidity, or salinity. Root branching is an extremely flexible means to rapidly adjust the overall surface of the root system and plants have evolved efficient control mechanisms, including, firstly initiation, when and where to start lateral root formation; secondly lateral root primordia organogenesis, during which the development of primordia can be arrested for a certain time; and thirdly lateral root emergence. Our review will focus on the most recent advances in understanding the molecular mechanisms involved in the regulation of lateral root initiation and organogenesis with the main focus on root system of the model plant Arabidopsis thaliana.}, author = {Eva Benková and Bielach, Agnieszka}, journal = {Current Opinion in Plant Biology}, number = {6}, pages = {677 -- 683}, publisher = {Elsevier}, title = {{Lateral root organogenesis - from cell to organ}}, doi = {10.1016/j.pbi.2010.09.006}, volume = {13}, year = {2010}, } @article{2873, abstract = {Nitrate is both a nitrogen source for higher plants and a signal molecule regulating their development. In Arabidopsis, the NRT1.1 nitrate transporter is crucial for nitrate signaling governing root growth, and has been proposed to act as a nitrate sensor. However, the sensing mechanism is unknown. Herein we show that NRT1.1 not only transports nitrate but also facilitates uptake of the phytohormone auxin. Moreover, nitrate inhibits NRT1.1-dependent auxin uptake, suggesting that transduction of nitrate signal by NRT1.1 is associated with a modification of auxin transport. Among other effects, auxin stimulates lateral root development. Mutation of NRT1.1 enhances both auxin accumulation in lateral roots and growth of these roots at low, but not high, nitrate concentration. Thus, we propose that NRT1.1 represses lateral root growth at low nitrate availability by promoting basipetal auxin transport out of these roots. This defines a mechanism connecting nutrient and hormone signaling during organ development.}, author = {Krouk, Gabriel and Lacombe, Benoît and Bielach, Agnieszka and Perrine-Walker, Francine and Malínská, Kateřina and Mounier, Emmanuelle and Hoyerová, Klára and Tillard, Pascal and Leon, Sarah and Ljung, Karin and Zažímalová, Eva and Eva Benková and Nacry, Philippe and Gojon, Alain}, journal = {Developmental Cell}, number = {6}, pages = {927 -- 937}, publisher = {Cell Press}, title = {{Nitrate-regulated auxin transport by NRT1.1 defines a mechanism for nutrient sensing in plants}}, doi = {10.1016/j.devcel.2010.05.008}, volume = {18}, year = {2010}, } @article{2899, abstract = {Toxin–antitoxin (TA) systems are commonly found on bacterial plasmids. The antitoxin inhibits toxin activity unless the system is lost from the cell. Then the shorter lived antitoxin degrades and the cell becomes susceptible to the toxin. Selection for plasmid-encoded TA systems was initially thought to result from their reducing the number of plasmid-free cells arising during growth in monoculture. However, modelling and experiments have shown that this mechanism can only explain the success of plasmid TA systems under a restricted set of conditions. Previously, we have proposed and tested an alternative model explaining the success of plasmid TA systems as a consequence of competition occurring between plasmids during co-infection of bacterial hosts. Here, we test a further prediction of this model, that competition between plasmids will lead to the biased accumulation of TA systems on plasmids relative to chromosomes. Transposon-encoded TA systems were added to populations of plasmid-containing cells, such that TA systems could insert into either plasmids or chromosomes. These populations were enriched for transposon-containing cells and then incubated in environments that did, or did not, allow effective within-host plasmid competition to occur. Changes in the ratio of plasmid- to chromosome-encoded TA systems were monitored. In agreement with our model, we found that plasmid-encoded TA systems had a competitive advantage, but only when host cells were sensitive to the effect of TA systems. This result demonstrates that within-host competition between plasmids can select for TA systems.}, author = {Cooper, Tim F and Tiago Paixao and Heinemann, Jack A}, journal = {Proc R Soc B}, number = {1697}, pages = {3149 -- 3155}, publisher = {Wiley-Blackwell}, title = {{Within host competition selects for plasmid encoded toxin–antitoxin systems}}, doi = {10.1098/rspb.2010.0831}, volume = {277}, year = {2010}, }