@article{2502, abstract = {In order to acquire phase-contrast images with adequate contrast, conventional TEM requires large amount of defocus. Increasing the defocus improves the low-frequency components but attenuates the high-frequency ones. On the other hand, Zernike phase-contrast TEM (ZPC-TEM) can recover low-frequency components without losing the high-frequency ones under in-focus conditions. ZPC-TEM however, has another problem, especially in imaging of complex biological specimens such as cells and tissues; strong halos appear around specimen structures, and these halos hinder the interpretation of images. Due to this problem, the application of ZPC-TEM has been restricted to imaging of smaller particles. In order to improve the halo appearance, we fabricated a new quarter-wave thin film phase-plate with a smaller central hole and tested it on vitreous biological specimens. ZPC-TEM with the new plate could successfully visualize, in in-focus images, the intracellular fine features of cultured cells and brain tissues. This result indicates that reduction of the central hole diameter makes ZPC-TEM applicable on size scales ranging from protein particles to tissue sections. The application of ZPC-TEM to vitreous biological specimens will be a powerful method to advance the new field of imaging science for ultrastructures in close-to-physiological state.}, author = {Fukuda, Yoshiyuki and Fukazawa, Yugo and Danev, Radostin S and Ryuichi Shigemoto and Nagayama, Kuniaki}, journal = {Journal of Structural Biology}, number = {3}, pages = {476 -- 484}, publisher = {Academic Press}, title = {{Tuning of the Zernike phase-plate for visualization of detailed ultrastructure in complex biological specimens}}, doi = {10.1016/j.jsb.2009.08.011}, volume = {168}, year = {2009}, } @article{2680, abstract = {GABA B receptor subtypes are based on the subunit isoforms GABA B1a and GABA B1b, which associate with GABA B2 subunits to form pharmacologically indistinguishable GABA B(1a,2) and GABA B(1b,2) receptors. Studies with mice selectively expressing GABA B1a or GABA B1b subunits revealed that GABA B(1a,2) receptors are more abundant than GABA B(1b,2) receptors at glutamatergic terminals. Accordingly, it was found that GABA B(1a,2) receptors are more efficient than GABA B(1b,2) receptors in inhibiting glutamate release when maximally activated by exogenous application of the agonist baclofen. Here, we used a combination of genetic, ultrastructural and electrophysiological approaches to analyze to what extent GABA B(1a,2) and GABA B(1b,2) receptors inhibit glutamate release in response to physiological activation. We first show that at hippocampal mossy fiber (MF)-CA3 pyramidal neuron synapses more GABA B1a than GABA B1b protein is present at presynaptic sites, consistent with the findings at other glutamatergic synapses. In the presence of baclofen at concentrations ≥1 μM, both GABA B(1a,2) and GABA B(1b,2) receptors contribute to presynaptic inhibition of glutamate release. However, at lower concentrations of baclofen, selectively GABA B(1a,2) receptors contribute to presynaptic inhibition. Remarkably, exclusively GABA B(1a,2) receptors inhibit glutamate release in response to synaptically released GABA. Specifically, we demonstrate that selectively GABA B(1a,2) receptors mediate heterosynaptic depression of MF transmission, a physiological phenomenon involving transsynaptic inhibition of glutamate release via presynaptic GABA B receptors. Our data demonstrate that the difference in GABA B1a and GABA B1b protein levels at MF terminals is sufficient to produce a strictly GABA B1a-specific effect under physiological conditions. This consolidates that the differential subcellular localization of the GABA B1a and GABA B1b proteins is of regulatory relevance. }, author = {Guetg, Nicole and Seddik, Riad and Vigot, Réjan and Tureček, Rostislav and Gassmann, Martin and Vogt, Kaspar E and Bräuner-Osborne, Hans and Ryuichi Shigemoto and Kretz, Oliver and Frotscher, Michael and Kulik, Ákos and Bettler, Bernhard}, journal = {Journal of Neuroscience}, number = {5}, pages = {1414 -- 1423}, publisher = {Society for Neuroscience}, title = {{The GABA B1a isoform mediates heterosynaptic depression at hippocampal mossy fiber synapses}}, doi = {10.1523/JNEUROSCI.3697-08.2009}, volume = {29}, year = {2009}, } @article{2682, abstract = {The living cell imaging using a two-photon microscope using gold nanoplates and nanoparticle aggregates was demonstrated. The dimensions of the nanoplates were determined through scanning electron microscopy (SEM) and atomic force microscopy. The height of a 100 nm base-length nanotriangle was around 10 nm, while the height of 300 nm base-length nanotriangle was around 12 nm. A spectrophotometer was also used to determine the extinction spectra of gold nanoparticle colloids. Two-photon-induced photoluminescence (TPIPL) under far-field excitation was tested for gold nanoplates on a glass substrate using two-photon laser scanning microscopy (TPLSM). It was observed that living-cell microscopic imaging can be carried out with TPIPL from gold nanoplates and aggregated nanosphere. This method provided a platform for developing tools for biological and biomedical studies.}, author = {Jiang, Yuqiang and Horimoto, Noriko N and Imura, Kohei and Matsui, Ko and Ryuichi Shigemoto}, journal = {Advanced Materials}, number = {22}, pages = {2309 -- 2313}, publisher = {Wiley-Blackwell}, title = {{Bioimaging with two-photon-induced luminescence from triangular nanoplates and nanoparticle aggregates of gold}}, doi = {10.1002/adma.200802312}, volume = {21}, year = {2009}, } @article{2683, abstract = {GABAb receptor (GABAbR)-mediated suppression of glutamate release is critical for limiting glutamatergic transmission across the central nervous system (CNS). Here we show that, upon tetanic stimulation of afferents to lateral amygdala, presynaptic GABAbR-mediated inhibition only occurs in glutamatergic inputs to principle neurons (PNs), not to interneurons (INs), despite the presence of GABAbR in terminals to both types of neurons. The selectivity is caused by differential local GABA accumulation; it requires GABA reuptake and parallels distinct spatial distributions of presynaptic GABAbR in terminals to PNs and INs. Moreover, GABAbR-mediated suppression of theta-burst-induced long-term potentiation (LTP) occurs only in the inputs to PNs, not to INs. Thus, target-cell-specific control of glutamate release by presynaptic GABAbR orchestrates the inhibitory dominance inside amygdala and might contribute to prevention of nonadaptive defensive behaviors.}, author = {Pan, Bingxing and Dong, Yu-Lin and Ito, Wataru and Yanagawa, Yuchio and Ryuichi Shigemoto and Morozov, Alexei A}, journal = {Neuron}, number = {6}, pages = {917 -- 929}, publisher = {Elsevier}, title = {{Selective gating of glutamatergic inputs to excitatory neurons of amygdala by presynaptic GABAb receptor}}, doi = {10.1016/j.neuron.2009.01.029}, volume = {61}, year = {2009}, } @article{2684, abstract = {Calcium-activated potassium channels have been shown to be critically involved in neuronal function, but an elucidation of their detailed roles awaits identification of the microdomains where they are located. This study was undertaken to unravel the precise subcellular distribution of the large-conductance calcium-activated potassium channels (called BK, KCa1.1, or Slo1) in the somatodendritic compartment of cerebellar Purkinje cells by means of postembedding immunogold cytochemistry and SDS-digested freeze-fracture replica labeling (SDS-FRL). We found BK channels to be unevenly distributed over the Purkinje cell plasma membrane. At distal dendritic compartments, BK channels were scattered over the plasma membrane of dendritic shafts and spines but absent from postsynaptic densities. At the soma and proximal dendrites, BK channels formed two distinct pools. One pool was scattered over the plasma membrane, whereas the other pool was clustered in plasma membrane domains overlying subsurface cisterns. The labeling density ratio of clustered to scattered channels was about 60:1, established in SDS-FRL. Subsurface cisterns, also called hypolemmal cisterns, are subcompartments of the endoplasmic reticulum likely representing calciosomes that unload and refill Ca2+ independently. Purkinje cell subsurface cisterns are enriched in inositol 1,4,5-triphosphate receptors that mediate the effects of several neurotransmitters, hormones, and growth factors by releasing Ca2+ into the cytosol, generating local Ca2+ sparks. Such increases in cytosolic [Ca2+] may be sufficient for BK channel activation. Clustered BK channels in the plasma membrane may thus participate in building a functional unit (plasmerosome) with the underlying calciosome that contributes significantly to local signaling in Purkinje cells.}, author = {Walter Kaufmann and Ferraguti, Francesco and Fukazawa, Yugo and Kasugai, Yu and Ryuichi Shigemoto and Laake, Petter and Sexton, Joseph A and Ruth, Peter and Wietzorrek, Georg and Knaus, Hans G and Storm, Johan F and Ottersen, Ole P}, journal = {Journal of Comparative Neurology}, number = {2}, pages = {215 -- 230}, publisher = {Wiley-Blackwell}, title = {{Large-conductance calcium-activated potassium channels in Purkinje cell plasma membranes are clustered at sites of hypolemmal microdomains}}, doi = {10.1002/cne.22066}, volume = {515}, year = {2009}, } @article{2685, abstract = {Conduction velocity (CV) of myelinated axons has been shown to be regulated by oligodendrocytes even after myelination has been completed. However, how myelinating oligodendrocytes regulate CV, and what the significance of this regulation is for normal brain function remain unknown. To address these questions, we analyzed a transgenic mouse line harboring extra copies of the myelin proteolipid protein 1 (plp1) gene (plp1tg/- mice) at 2 months of age. At this stage, the plp1tg/- mice have an unaffected myelin structure with a normally appearing ion channel distribution, but the CV in all axonal tracts tested in the CNS is greatly reduced. We also found decreased axonal diameters and slightly abnormal paranodal structures, both of which can be a cause for the reduced CV. Interestingly the plp1tg/- mice showed altered anxiety-like behaviors, reduced prepulse inhibitions, spatial learning deficits and working memory deficit, all of which are schizophrenia-related behaviors. Our results implicate that abnormalities in the neuron-glia interactions at the paranodal junctions can result in reduced CV in the CNS, which then induces behavioral abnormalities related to schizophrenia.}, author = {Tanaka, Hisataka and Ma, Jianmei and Tanaka, Kenji F and Takao, Keizo and Komada, Munekazu and Tanda, Koichi and Suzuki, Ayaka and Ishibashi, Tomoko and Baba, Hiroko and Isa, Tadashi and Ryuichi Shigemoto and Ono, Katsuhiko and Miyakawa, Tsuyoshi and Ikenaka, Kazuhiro}, journal = {Journal of Neuroscience}, number = {26}, pages = {8363 -- 8371}, publisher = {Society for Neuroscience}, title = {{Mice with altered myelin proteolipid protein gene expression display cognitive deficits accompanied by abnormal neuron-glia interactions and decreased conduction velocities}}, doi = {10.1523/JNEUROSCI.3216-08.2009}, volume = {29}, year = {2009}, } @article{2686, abstract = {Channelrhodopsin-2 (ChR2), one of the archea-type rhodopsins from green algae, is a potentially useful optogenetic tool for restoring vision in patients with photoreceptor degeneration, such as retinitis pigmentosa. If the ChR2 gene is transferred to retinal ganglion cells (RGCs), which send visual information to the brain, the RGCs may be repurposed to act as photoreceptors. In this study, by using a transgenic rat expressing ChR2 specifically in the RGCs under the regulation of a Thy-1.2 promoter, we tested the possibility that direct photoactivation of RGCs could restore effective vision. Although the contrast sensitivities of the optomotor responses of transgenic rats were similar to those observed in the wild-type rats, they were enhanced for visual stimuli of low-spatial frequency after the degeneration of native photoreceptors. This result suggests that the visual signals derived from the ChR2-expressing RGCs were reinterpreted by the brain to form behavior-related vision.}, author = {Tomita, Hiroshi and Sugano, Eriko and Fukazawa, Yugo and Isago, Hitomi and Sugiyama, Yuka and Hiroi, Teru and Ishizuka, Toru and Mushiake, Hajime and Kato, Megumi and Hirabayashi, Masumi and Ryuichi Shigemoto and Yawo, Hiromu and Tamai, Makoto}, journal = {PLoS One}, number = {11}, publisher = {Public Library of Science}, title = {{Visual properties of transgenic rats harboring the channelrhodopsin-2 gene regulated by the thy-1.2 promoter}}, doi = {10.1371/journal.pone.0007679}, volume = {4}, year = {2009}, } @article{2703, abstract = {We consider N×N Hermitian random matrices with i.i.d. entries. The matrix is normalized so that the average spacing between consecutive eigenvalues is of order 1/N. We study the connection between eigenvalue statistics on microscopic energy scales η≪1 and (de)localization properties of the eigenvectors. Under suitable assumptions on the distribution of the single matrix elements, we first give an upper bound on the density of states on short energy scales of order η∼log N/N. We then prove that the density of states concentrates around the Wigner semicircle law on energy scales η≫N−2/3. We show that most eigenvectors are fully delocalized in the sense that their ℓp-norms are comparable with N1/p−1/2 for p≥2, and we obtain the weaker bound N2/3(1/p−1/2) for all eigenvectors whose eigenvalues are separated away from the spectral edges. We also prove that, with a probability very close to one, no eigenvector can be localized. Finally, we give an optimal bound on the second moment of the Green function. }, author = {László Erdös and Schlein, Benjamin and Yau, Horng-Tzer}, journal = {Annals of Probability}, number = {3}, pages = {815 -- 852}, publisher = {Institute of Mathematical Statistics}, title = {{Semicircle law on short scales and delocalization of eigenvectors for Wigner random matrices}}, doi = {10.1214/08-AOP421}, volume = {37}, year = {2009}, } @article{2757, abstract = {We propose a new approach for the study of the time evolution of a factorized N-particle bosonic wave function with respect to a mean-field dynamics with a bounded interaction potential. The new technique, which is based on the control of the growth of the correlations among the particles, leads to quantitative bounds on the difference between the many-particle Schrödinger dynamics and the one-particle nonlinear Hartree dynamics. In particular the one-particle density matrix associated with the solution to the N-particle Schrödinger equation is shown to converge to the projection onto the one-dimensional sub-space spanned by the solution to the Hartree equation with a speed of convergence of order 1/N for all fixed times.}, author = {László Erdös and Schlein, Benjamin}, journal = {Journal of Statistical Physics}, number = {5-6}, pages = {859 -- 870}, publisher = {Springer}, title = {{Quantum dynamics with mean field interactions: A new approach}}, doi = {10.1007/s10955-008-9570-7}, volume = {134}, year = {2009}, } @article{2758, abstract = {We consider N × N Hermitian random matrices with independent identical distributed entries. The matrix is 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 prove that, away from the spectral edges, the density of eigenvalues concentrates around the Wigner semicircle law on energy scales n ≫ N -1 (log N) 8 . Up to the logarithmic factor, this is the smallest energy scale for which the semicircle law may be valid. We also prove that for all eigenvalues away from the spectral edges, the -tempℓ∞-norm of the corresponding eigenvectors is of order O(N -1/2), modulo logarithmic corrections. The upper bound O(N -1/2) implies that every eigenvector is completely delocalized, i.e., the maximum size of the components of the eigenvector is of the same order as their average size. In the Appendix, we include a lemma by J. Bourgain which removes one of our assumptions on the distribution of the matrix elements.}, author = {László Erdös and Schlein, Benjamin and Yau, Horng-Tzer}, journal = {Communications in Mathematical Physics}, number = {2}, pages = {641 -- 655}, publisher = {Springer}, title = {{Local semicircle law and complete delocalization for Wigner random matrices}}, doi = {10.1007/s00220-008-0636-9}, volume = {287}, year = {2009}, } @article{2759, abstract = {We consider the evolution of N bosons interacting with a repulsive short range pair potential in three dimensions. The potential is scaled according to the Gross-Pitaevskii scaling, i.e. it is given by N 2 V(N(x i - x j )). We monitor the behaviour of the solution to the N-particle Schrödinger equation in a spatial window where two particles are close to each other. We prove that within this window a short-scale interparticle structure emerges dynamically. The local correlation between the particles is given by the two-body zero energy scattering mode. This is the characteristic structure that was expected to form within a very short initial time layer and to persist for all later times, on the basis of the validity of the Gross-Pitaevskii equation for the evolution of the Bose-Einstein condensate. The zero energy scattering mode emerges after an initial time layer where all higher energy modes disperse out of the spatial window. We can prove the persistence of this structure up to sufficiently small times before three-particle correlations could develop.}, author = {László Erdös and Michelangeli, Alessandro and Schlein, Benjamin}, journal = {Communications in Mathematical Physics}, number = {3}, pages = {1171 -- 1210}, publisher = {Springer}, title = {{Dynamical formation of correlations in a Bose-Einstein condensate}}, doi = {10.1007/s00220-009-0828-y}, volume = {289}, year = {2009}, } @article{2760, author = {László Erdös and Schlein, Benjamin and Yau, Horng-Tzer}, journal = {Journal of the American Mathematical Society}, number = {4}, pages = {1099 -- 1156}, publisher = {American Mathematical Society}, title = {{Rigorous derivation of the gross-pitaevskii equation with a large interaction potential}}, doi = {10.1090/S0894-0347-09-00635-3}, volume = {22}, year = {2009}, } @article{2796, abstract = {As reported in a number of recent studies, turbulence in pipe flow is transient for Re<2000 and the flow eventually always returns to the laminar state. Generally, the lifetime of turbulence has been observed to increase rapidly with Reynolds number but there is currently no accord on the exact scaling behaviour. In particular, it is not clear whether a critical point exists where turbulence becomes sustained or if it remains transient. We here aim to clarify if these conflicting results may have been caused by the different experimental and numerical protocols used to trigger turbulence in these studies.}, author = {de Lózar, Alberto and Björn Hof}, journal = {Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences}, number = {1888}, pages = {589 -- 599}, publisher = {Royal Society of London}, title = {{An experimental study of the decay of turbulent puffs in pipe flow}}, doi = {10.1098/rsta.2008.0199}, volume = {367}, year = {2009}, } @inproceedings{2797, abstract = {In pipe flow at low Reynolds number, decay of localized disturbances is observed. As the Reynolds number is increased, the question emerges whether the life time of these disturbances diverges at a finite Reynolds number or remains transient. In the current investigation we determine their life time quantitatively from pressure measurements, while in previous investigations the distance over which a structure survives has been determined. The obtained results confirm that the life time of localized disturbances does not diverge in the range of Reynolds numbers covered in the current experiment.}, author = {Kuik, Dirk J and Poelma, Christian and Björn Hof and Westerweel, Jerry}, pages = {145 -- 148}, publisher = {Springer}, title = {{Quantitative measurement of the life time of turbulence in pipe flow}}, doi = {10.1007/978-3-642-03085-7_36}, volume = {132}, year = {2009}, } @article{2868, abstract = {Plants exhibit an amazing developmental flexibility. Plant embryogenesis results in the establishment of a simple apical-basal axis represented by apical shoot and basal root meristems. Later, during postembryonic growth, shaping of the plant body continues by the formation and activation of numerous adjacent meristems that give rise to lateral shoot branches, leaves, flowers, or lateral roots. This developmental plasticity reflects an important feature of the plant's life strategy based on the rapid reaction to different environmental stimuli, such as temperature fluctuations, availability of nutrients, light or water and response resulting in modulation of developmental programs. Plant hormones are important endogenous factors for the integration of these environmental inputs and regulation of plant development. After a period of studies focused primarily on single hormonal pathways that enabled us to understand the hormone perception and signal transduction mechanisms, it became obvious that the developmental output mediated by a single hormonal pathway is largely modified through a whole network of interactions with other hormonal pathways. In this review, we will summarize recent knowledge on hormonal networks that regulate the development and growth of root with focus on the hormonal interactions that shape the root apical meristem. }, author = {Eva Benková and Hejátko, Jan}, journal = {Plant Molecular Biology}, number = {4}, pages = {383 -- 396}, publisher = {Springer}, title = {{Hormone interactions at the root apical meristem}}, doi = {10.1007/s11103-008-9393-6}, volume = {69}, year = {2009}, } @article{2869, abstract = {Lateral root formation is a major determinant of root systems architecture. The degree of root branching impacts the efficiency of water uptake, acquisition of nutrients and anchorage by plants. Understanding the regulation of lateral root development is therefore of vital agronomic importance. The molecular and cellular basis of lateral root formation has been most extensively studied in the plant model Arabidopsis thaliana (Arabidopsis). Significant progress has recently been made in identifying many new Arabidopsis genes that regulate lateral root initiation, patterning and emergence processes. We review how these studies have revealed that the plant hormone auxin represents a common signal that integrates these distinct yet interconnected developmental processes.}, author = {Péret, Benjamin and De Rybel, Bert and Casimiro, Ilda and Eva Benková and Swarup, Ranjan and Laplaze, Laurent and Beeckman, Tom and Bennett, Malcolm J}, journal = {Trends in Plant Science}, number = {7}, pages = {399 -- 408}, publisher = {Cell Press}, title = {{Arabidopsis lateral root development: an emerging story}}, doi = {10.1016/j.tplants.2009.05.002}, volume = {14}, year = {2009}, } @article{2932, abstract = {We describe a new implementation of the Edmonds’s algorithm for computing a perfect matching of minimum cost, to which we refer as Blossom V. A key feature of our implementation is a combination of two ideas that were shown to be effective for this problem: the “variable dual updates” approach of Cook and Rohe (INFORMS J Comput 11(2):138–148, 1999) and the use of priority queues. We achieve this by maintaining an auxiliary graph whose nodes correspond to alternating trees in the Edmonds’s algorithm. While our use of priority queues does not improve the worst-case complexity, it appears to lead to an efficient technique. In the majority of our tests Blossom V outperformed previous implementations of Cook and Rohe (INFORMS J Comput 11(2):138–148, 1999) and Mehlhorn and Schäfer (J Algorithmics Exp (JEA) 7:4, 2002), sometimes by an order of magnitude. We also show that for large VLSI instances it is beneficial to update duals by solving a linear program, contrary to a conjecture by Cook and Rohe. }, author = {Vladimir Kolmogorov}, journal = {Mathematical Programming Computation}, number = {1}, pages = {43 -- 67}, publisher = {Springer}, title = {{Blossom V: A new implementation of a minimum cost perfect matching algorithm}}, doi = {10.1007/s12532-009-0002-8}, volume = {1}, year = {2009}, } @article{3046, abstract = {Plant-parasitic nematodes are destructive plant pathogens that cause significant yield losses. They induce highly specialized feeding sites (NFS) in infected plant roots from which they withdraw nutrients. In order to establish these NFS, it is thought that the nematodes manipulate the molecular and physiological pathways of their hosts. Evidence is accumulating that the plant signalling molecule auxin is involved in the initiation and development of the feeding sites of sedentary plant-parasitic nematodes. Intercellular transport of auxin is essential for various aspects of plant growth and development. Here, we analysed the spatial and temporal expression of PIN auxin transporters during the early events of NFS establishment using promoter-GUS/GFP fusion lines. Additionally, single and double pin mutants were used in infection studies to analyse the role of the different PIN proteins during cyst nematode infection. Based on our results, we postulate a model in which PIN1-mediated auxin transport is needed to deliver auxin to the initial syncytial cell, whereas PIN3 and PIN4 distribute the accumulated auxin laterally and are involved in the radial expansion of the NFS. Our data demonstrate that cyst nematodes are able to hijack the auxin distribution network in order to facilitate the infection process. © 2009 Grunewald et al}, author = {Grunewald, Wim and Cannoot, Bernard and Jirí Friml and Gheysen, Godelieve}, journal = {PLoS Pathogens}, number = {1}, publisher = {Public Library of Science}, title = {{Parasitic nematodes modulate PIN mediated auxin transport to facilitate infection}}, doi = { 10.1371/journal.ppat.1000266}, volume = {5}, year = {2009}, } @article{3047, abstract = { Auxin transport is mediated at the cellular level by three independent mechanisms that are characterised by the PIN-formed (PIN), P-glycoprotein (ABCB/PGP) and AUX/LAX transport proteins. The PIN and ABCB transport proteins, best represented by PIN1 and ABCB19 (PGP19), have been shown to coordinately regulate auxin efflux. When PIN1 and ABCB19 coincide on the plasma membrane, their interaction enhances the rate and specificity of auxin efflux and the dynamic cycling of PIN1 is reduced. However, ABCB19 function is not regulated by the dynamic cellular trafficking mechanisms that regulate PIN1 in apical tissues, as localisation of ABCB19 on the plasma membrane was not inhibited by short-term treatments with latrunculin B, oryzalin, brefeldin A (BFA) or wortmannin - all of which have been shown to alter PIN1 and/or PIN2 plasma membrane localisation. When taken up by endocytosis, the styryl dye FM4-64 labels diffuse rather than punctuate intracellular bodies in abcb19 (pgp19), and some aggregations of PIN1 induced by short-term BFA treatment did not disperse after BFA washout in abcb19. Although the subcellular localisations of ABCB19 and PIN1 in the reciprocal mutant backgrounds were like those in wild type, PIN1 plasma membrane localisation in abcb19 roots was more easily perturbed by the detergent Triton X-100, but not other non-ionic detergents. ABCB19 is stably associated with sterol/sphingolipid-enriched membrane fractions containing BIG/TIR3 and partitions into Triton X-100 detergent-resistant membrane (DRM) fractions. In the wild type, PIN1 was also present in DRMs, but was less abundant in abcb19 DRMs. These observations suggested a rationale for the observed lack of auxin transport activity when PIN1 is expressed in a non-plant heterologous system. PIN1 was therefore expressed in Schizosaccharomyces pombe, which has plant-like sterol-enriched microdomains, and catalysed auxin transport in these cells. These data suggest that ABCB19 stabilises PIN1 localisation at the plasma membrane in discrete cellular subdomains where PIN1 and ABCB19 expression overlaps. }, author = {Titapiwatanakun, Boosaree and Blakeslee, Joshua and Bandyopadhyay, Anindita and Yang, Haibing and Mravec, Jozef and Sauer, Michael and Cheng, Yan and Adamec, Jiří and Nagashima, Akitomo and Geisler, Markus and Sakai, Tatsuya and Jirí Friml and Peer, Wendy A and Murphy, Angus S}, journal = {Plant Journal}, number = {1}, pages = {27 -- 44}, publisher = {Wiley-Blackwell}, title = {{ABCB19 PGP19 stabilises PIN1 in membrane microdomains in Arabidopsis}}, doi = {10.1111/j.1365-313X.2008.03668.x}, volume = {57}, year = {2009}, } @article{3048, abstract = {Endocytic vesicle trafficking is crucial for regulating activity and localization of plasma membrane components, but the process is still poorly genetically defined in plants. Membrane proteins of the PIN-FORMED (PIN) family exhibit polar localization in plant cells and facilitate cellular efflux of the plant hormone auxin, thereby regulating multiple developmental processes [1, 2]. PIN proteins undergo constitutive endocytosis and GNOM ARF GEF-dependent recycling [3-5], and their localization is under extensive regulation by developmental and environmental cues [6-9]. We designed a fluorescence imaging-based screen to identify Arabidopsis thaliana mutants defective in internalization of proteins including PINs from the plasma membrane. We identified three mutant loci, BFA-visualized endocytic trafficking defective1 (ben1) through ben3 that do not efficiently accumulate PIN1-GFP in intracellular compartments after inhibition of recycling and secretion by fungal toxin brefeldin A (BFA). Fine mapping revealed that BEN1 encodes an ARF GEF vesicle trafficking regulator from the functionally uncharacterized BIG class. ben1 mutant has been previously implicated in pathogen response [10] and shows cell polarity, BFA sensitivity, and growth defects. BEN1 is involved in endocytosis of plasma membrane proteins and localizes to early endocytic compartments distinct from GNOM-positive endosomes. Our results identify BEN1 as the ARF GEF mediating early endosomal traffic.}, author = {Tanaka, Hirokazu and Kitakura, Saeko and De Rycke, Riet M and De Groodt, Ruth and Jirí Friml}, journal = {Current Biology}, number = {5}, pages = {391 -- 397}, publisher = {Cell Press}, title = {{Fluorescence imaging based screen identifies ARF GEF component of early endosomal trafficking}}, doi = {10.1016/j.cub.2009.01.057}, volume = {19}, year = {2009}, }