TY - JOUR AB - We consider the sum of two large Hermitian matrices A and B with a Haar unitary conjugation bringing them into a general relative position. We prove that the eigenvalue density on the scale slightly above the local eigenvalue spacing is asymptotically given by the free additive convolution of the laws of A and B as the dimension of the matrix increases. This implies optimal rigidity of the eigenvalues and optimal rate of convergence in Voiculescu's theorem. Our previous works [4], [5] established these results in the bulk spectrum, the current paper completely settles the problem at the spectral edges provided they have the typical square-root behavior. The key element of our proof is to compensate the deterioration of the stability of the subordination equations by sharp error estimates that properly account for the local density near the edge. Our results also hold if the Haar unitary matrix is replaced by the Haar orthogonal matrix. AU - Bao, Zhigang AU - Erdös, László AU - Schnelli, Kevin ID - 10862 IS - 7 JF - Journal of Functional Analysis KW - Analysis SN - 0022-1236 TI - Spectral rigidity for addition of random matrices at the regular edge VL - 279 ER - TY - JOUR AB - In this paper we find a tight estimate for Gromov’s waist of the balls in spaces of constant curvature, deduce the estimates for the balls in Riemannian manifolds with upper bounds on the curvature (CAT(ϰ)-spaces), and establish similar result for normed spaces. AU - Akopyan, Arseniy AU - Karasev, Roman ID - 10867 IS - 3 JF - International Mathematics Research Notices KW - General Mathematics SN - 1073-7928 TI - Waist of balls in hyperbolic and spherical spaces VL - 2020 ER - TY - GEN AB - Fitness interactions between mutations can influence a population’s evolution in many different ways. While epistatic effects are difficult to measure precisely, important information is captured by the mean and variance of log fitnesses for individuals carrying different numbers of mutations. We derive predictions for these quantities from a class of simple fitness landscapes, based on models of optimizing selection on quantitative traits. We also explore extensions to the models, including modular pleiotropy, variable effect sizes, mutational bias and maladaptation of the wild type. We illustrate our approach by reanalysing a large dataset of mutant effects in a yeast snoRNA. Though characterized by some large epistatic effects, these data give a good overall fit to the non-epistatic null model, suggesting that epistasis might have limited influence on the evolutionary dynamics in this system. We also show how the amount of epistasis depends on both the underlying fitness landscape and the distribution of mutations, and so is expected to vary in consistent ways between new mutations, standing variation and fixed mutations. AU - Fraisse, Christelle AU - Welch, John J. ID - 9799 TI - Simulation code for Fig S1 from the distribution of epistasis on simple fitness landscapes ER - TY - GEN AB - Fitness interactions between mutations can influence a population’s evolution in many different ways. While epistatic effects are difficult to measure precisely, important information is captured by the mean and variance of log fitnesses for individuals carrying different numbers of mutations. We derive predictions for these quantities from a class of simple fitness landscapes, based on models of optimizing selection on quantitative traits. We also explore extensions to the models, including modular pleiotropy, variable effect sizes, mutational bias and maladaptation of the wild type. We illustrate our approach by reanalysing a large dataset of mutant effects in a yeast snoRNA. Though characterized by some large epistatic effects, these data give a good overall fit to the non-epistatic null model, suggesting that epistasis might have limited influence on the evolutionary dynamics in this system. We also show how the amount of epistasis depends on both the underlying fitness landscape and the distribution of mutations, and so is expected to vary in consistent ways between new mutations, standing variation and fixed mutations. AU - Fraisse, Christelle AU - Welch, John J. ID - 9798 TI - Simulation code for Fig S2 from the distribution of epistasis on simple fitness landscapes ER - TY - JOUR AB - We prove a central limit theorem for the difference of linear eigenvalue statistics of a sample covariance matrix W˜ and its minor W. We find that the fluctuation of this difference is much smaller than those of the individual linear statistics, as a consequence of the strong correlation between the eigenvalues of W˜ and W. Our result identifies the fluctuation of the spatial derivative of the approximate Gaussian field in the recent paper by Dumitru and Paquette. Unlike in a similar result for Wigner matrices, for sample covariance matrices, the fluctuation may entirely vanish. AU - Cipolloni, Giorgio AU - Erdös, László ID - 6488 IS - 3 JF - Random Matrices: Theory and Application SN - 20103263 TI - Fluctuations for differences of linear eigenvalue statistics for sample covariance matrices VL - 9 ER - TY - JOUR AB - Research in the field of colloidal semiconductor nanocrystals (NCs) has progressed tremendously, mostly because of their exceptional optoelectronic properties. Core@shell NCs, in which one or more inorganic layers overcoat individual NCs, recently received significant attention due to their remarkable optical characteristics. Reduced Auger recombination, suppressed blinking, and enhanced carrier multiplication are among the merits of core@shell NCs. Despite their importance in device development, the influence of the shell and the surface modification of the core@shell NC assemblies on the charge carrier transport remains a pertinent research objective. Type-II PbTe@PbS core@shell NCs, in which exclusive electron transport was demonstrated, still exhibit instability of their electron ransport. Here, we demonstrate the enhancement of electron transport and stability in PbTe@PbS core@shell NC assemblies using iodide as a surface passivating ligand. The combination of the PbS shelling and the use of the iodide ligand contributes to the addition of one mobile electron for each core@shell NC. Furthermore, both electron mobility and on/off current modulation ratio values of the core@shell NC field-effect transistor are steady with the usage of iodide. Excellent stability in these exclusively electron-transporting core@shell NCs paves the way for their utilization in electronic devices. AU - Miranti, Retno AU - Septianto, Ricky Dwi AU - Ibáñez, Maria AU - Kovalenko, Maksym V. AU - Matsushita, Nobuhiro AU - Iwasa, Yoshihiro AU - Bisri, Satria Zulkarnaen ID - 8746 IS - 17 JF - Applied Physics Letters SN - 0003-6951 TI - Electron transport in iodide-capped core@shell PbTe@PbS colloidal nanocrystal solids VL - 117 ER - TY - JOUR AB - The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO2 emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal–air batteries have the highest theoretical energy density of all possible secondary battery technologies and could yield step changes in energy storage, if their practical difficulties could be overcome. The scope of this review is to provide an objective, comprehensive, and authoritative assessment of the intensive work invested in nonaqueous rechargeable metal–air batteries over the past few years, which identified the key problems and guides directions to solve them. We focus primarily on the challenges and outlook for Li–O2 cells but include Na–O2, K–O2, and Mg–O2 cells for comparison. Our review highlights the interdisciplinary nature of this field that involves a combination of materials chemistry, electrochemistry, computation, microscopy, spectroscopy, and surface science. The mechanisms of O2 reduction and evolution are considered in the light of recent findings, along with developments in positive and negative electrodes, electrolytes, electrocatalysis on surfaces and in solution, and the degradative effect of singlet oxygen, which is typically formed in Li–O2 cells. AU - Kwak, WJ AU - Sharon, D AU - Xia, C AU - Kim, H AU - Johnson, LR AU - Bruce, PG AU - Nazar, LF AU - Sun, YK AU - Frimer, AA AU - Noked, M AU - Freunberger, Stefan Alexander AU - Aurbach, D ID - 7985 IS - 14 JF - Chemical Reviews SN - 0009-2665 TI - Lithium-oxygen batteries and related systems: Potential, status, and future VL - 120 ER - TY - JOUR AB - Spontaneously arising channels that transport the phytohormone auxin provide positional cues for self-organizing aspects of plant development such as flexible vasculature regeneration or its patterning during leaf venation. The auxin canalization hypothesis proposes a feedback between auxin signaling and transport as the underlying mechanism, but molecular players await discovery. We identified part of the machinery that routes auxin transport. The auxin-regulated receptor CAMEL (Canalization-related Auxin-regulated Malectin-type RLK) together with CANAR (Canalization-related Receptor-like kinase) interact with and phosphorylate PIN auxin transporters. camel and canar mutants are impaired in PIN1 subcellular trafficking and auxin-mediated PIN polarization, which macroscopically manifests as defects in leaf venation and vasculature regeneration after wounding. The CAMEL-CANAR receptor complex is part of the auxin feedback that coordinates polarization of individual cells during auxin canalization. AU - Hajny, Jakub AU - Prat, Tomas AU - Rydza, N AU - Rodriguez Solovey, Lesia AU - Tan, Shutang AU - Verstraeten, Inge AU - Domjan, David AU - Mazur, E AU - Smakowska-Luzan, E AU - Smet, W AU - Mor, E AU - Nolf, J AU - Yang, B AU - Grunewald, W AU - Molnar, Gergely AU - Belkhadir, Y AU - De Rybel, B AU - Friml, Jiří ID - 8721 IS - 6516 JF - Science SN - 0036-8075 TI - Receptor kinase module targets PIN-dependent auxin transport during canalization VL - 370 ER - TY - JOUR AB - Organic materials are known to feature long spin-diffusion times, originating in a generally small spin–orbit coupling observed in these systems. From that perspective, chiral molecules acting as efficient spin selectors pose a puzzle that attracted a lot of attention in recent years. Here, we revisit the physical origins of chiral-induced spin selectivity (CISS) and propose a simple analytic minimal model to describe it. The model treats a chiral molecule as an anisotropic wire with molecular dipole moments aligned arbitrarily with respect to the wire’s axes and is therefore quite general. Importantly, it shows that the helical structure of the molecule is not necessary to observe CISS and other chiral nonhelical molecules can also be considered as potential candidates for the CISS effect. We also show that the suggested simple model captures the main characteristics of CISS observed in the experiment, without the need for additional constraints employed in the previous studies. The results pave the way for understanding other related physical phenomena where the CISS effect plays an essential role. AU - Ghazaryan, Areg AU - Paltiel, Yossi AU - Lemeshko, Mikhail ID - 7968 IS - 21 JF - The Journal of Physical Chemistry C SN - 1932-7447 TI - Analytic model of chiral-induced spin selectivity VL - 124 ER - TY - JOUR AB - Recent discoveries have shown that, when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between them, the electronic properties of the coupled system can be dramatically altered. Here, we demonstrate that a similar concept can be extended to the optics realm, particularly to propagating phonon polaritons–hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a vdW crystal (α-MoO3) supporting anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources. Our images reveal that, under a critical angle, the PhPs isofrequency curve undergoes a topological transition, in which the propagation of PhPs is strongly guided (canalization regime) along predetermined directions without geometric spreading. These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nanoimaging, (bio)-sensing, or heat management. AU - Duan, Jiahua AU - Capote-Robayna, Nathaniel AU - Taboada-Gutiérrez, Javier AU - Álvarez-Pérez, Gonzalo AU - Prieto Gonzalez, Ivan AU - Martín-Sánchez, Javier AU - Nikitin, Alexey Y. AU - Alonso-González, Pablo ID - 10866 IS - 7 JF - Nano Letters KW - Mechanical Engineering KW - Condensed Matter Physics KW - General Materials Science KW - General Chemistry KW - Bioengineering SN - 1530-6984 TI - Twisted nano-optics: Manipulating light at the nanoscale with twisted phonon polaritonic slabs VL - 20 ER - TY - JOUR AB - Dipolar (or spatially indirect) excitons (IXs) in semiconductor double quantum well (DQW) subjected to an electric field are neutral species with a dipole moment oriented perpendicular to the DQW plane. Here, we theoretically study interactions between IXs in stacked DQW bilayers, where the dipolar coupling can be either attractive or repulsive depending on the relative positions of the particles. By using microscopic band structure calculations to determine the electronic states forming the excitons, we show that the attractive dipolar interaction between stacked IXs deforms their electronic wave function, thereby increasing the inter-DQW interaction energy and making the IX even more electrically polarizable. Many-particle interaction effects are addressed by considering the coupling between a single IX in one of the DQWs to a cloud of IXs in the other DQW, which is modeled either as a closed-packed lattice or as a continuum IX fluid. We find that the lattice model yields IX interlayer binding energies decreasing with increasing lattice density. This behavior is due to the dominating role of the intra-DQW dipolar repulsion, which prevents more than one exciton from entering the attractive region of the inter-DQW coupling. Finally, both models shows that the single IX distorts the distribution of IXs in the adjacent DQW, thus inducing the formation of an IX dipolar polaron (dipolaron). While the interlayer binding energy reduces with IX density for lattice dipolarons, the continuous polaron model predicts a nonmonotonous dependence on density in semiquantitative agreement with a recent experimental study [cf. Hubert et al., Phys. Rev. X 9, 021026 (2019)]. AU - Hubert, C. AU - Cohen, K. AU - Ghazaryan, Areg AU - Lemeshko, Mikhail AU - Rapaport, R. AU - Santos, P. V. ID - 8588 IS - 4 JF - Physical Review B SN - 2469-9950 TI - Attractive interactions, molecular complexes, and polarons in coupled dipolar exciton fluids VL - 102 ER - TY - JOUR AB - One of the hallmarks of quantum statistics, tightly entwined with the concept of topological phases of matter, is the prediction of anyons. Although anyons are predicted to be realized in certain fractional quantum Hall systems, they have not yet been unambiguously detected in experiment. Here we introduce a simple quantum impurity model, where bosonic or fermionic impurities turn into anyons as a consequence of their interaction with the surrounding many-particle bath. A cloud of phonons dresses each impurity in such a way that it effectively attaches fluxes or vortices to it and thereby converts it into an Abelian anyon. The corresponding quantum impurity model, first, provides a different approach to the numerical solution of the many-anyon problem, along with a concrete perspective of anyons as emergent quasiparticles built from composite bosons or fermions. More importantly, the model paves the way toward realizing anyons using impurities in crystal lattices as well as ultracold gases. In particular, we consider two heavy electrons interacting with a two-dimensional lattice crystal in a magnetic field, and show that when the impurity-bath system is rotated at the cyclotron frequency, impurities behave as anyons as a consequence of the angular momentum exchange between the impurities and the bath. A possible experimental realization is proposed by identifying the statistics parameter in terms of the mean-square distance of the impurities and the magnetization of the impurity-bath system, both of which are accessible to experiment. Another proposed application is impurities immersed in a two-dimensional weakly interacting Bose gas. AU - Yakaboylu, Enderalp AU - Ghazaryan, Areg AU - Lundholm, D. AU - Rougerie, N. AU - Lemeshko, Mikhail AU - Seiringer, Robert ID - 8769 IS - 14 JF - Physical Review B SN - 2469-9950 TI - Quantum impurity model for anyons VL - 102 ER - TY - JOUR AB - Multilayer graphene lattices allow for an additional tunability of the band structure by the strong perpendicular electric field. In particular, the emergence of the new multiple Dirac points in ABA stacked trilayer graphene subject to strong transverse electric fields was proposed theoretically and confirmed experimentally. These new Dirac points dubbed “gullies” emerge from the interplay between strong electric field and trigonal warping. In this work, we first characterize the properties of new emergent Dirac points and show that the electric field can be used to tune the distance between gullies in the momentum space. We demonstrate that the band structure has multiple Lifshitz transitions and higher-order singularity of “monkey saddle” type. Following the characterization of the band structure, we consider the spectrum of Landau levels and structure of their wave functions. In the limit of strong electric fields when gullies are well separated in momentum space, they give rise to triply degenerate Landau levels. In the second part of this work, we investigate how degeneracy between three gully Landau levels is lifted in the presence of interactions. Within the Hartree-Fock approximation we show that the symmetry breaking state interpolates between the fully gully polarized state that breaks C3 symmetry at high displacement field and the gully symmetric state when the electric field is decreased. The discontinuous transition between these two states is driven by enhanced intergully tunneling and exchange. We conclude by outlining specific experimental predictions for the existence of such a symmetry-breaking state. AU - Rao, Peng AU - Serbyn, Maksym ID - 7971 IS - 24 JF - Physical Review B SN - 2469-9950 TI - Gully quantum Hall ferromagnetism in biased trilayer graphene VL - 101 ER - TY - JOUR AB - In laboratory studies and numerical simulations, we observe clear signatures of unstable time-periodic solutions in a moderately turbulent quasi-two-dimensional flow. We validate the dynamical relevance of such solutions by demonstrating that turbulent flows in both experiment and numerics transiently display time-periodic dynamics when they shadow unstable periodic orbits (UPOs). We show that UPOs we computed are also statistically significant, with turbulent flows spending a sizable fraction of the total time near these solutions. As a result, the average rates of energy input and dissipation for the turbulent flow and frequently visited UPOs differ only by a few percent. AU - Suri, Balachandra AU - Kageorge, Logan AU - Grigoriev, Roman O. AU - Schatz, Michael F. ID - 8634 IS - 6 JF - Physical Review Letters KW - General Physics and Astronomy SN - 0031-9007 TI - Capturing turbulent dynamics and statistics in experiments with unstable periodic orbits VL - 125 ER - TY - JOUR AB - Peptides derived from non-functional precursors play important roles in various developmental processes, but also in (a)biotic stress signaling. Our (phospho)proteome-wide analyses of C-terminally encoded peptide 5 (CEP5)-mediated changes revealed an impact on abiotic stress-related processes. Drought has a dramatic impact on plant growth, development and reproduction, and the plant hormone auxin plays a role in drought responses. Our genetic, physiological, biochemical and pharmacological results demonstrated that CEP5-mediated signaling is relevant for osmotic and drought stress tolerance in Arabidopsis, and that CEP5 specifically counteracts auxin effects. Specifically, we found that CEP5 signaling stabilizes AUX/IAA transcriptional repressors, suggesting the existence of a novel peptide-dependent control mechanism that tunes auxin signaling. These observations align with the recently described role of AUX/IAAs in stress tolerance and provide a novel role for CEP5 in osmotic and drought stress tolerance. AU - Smith, S AU - Zhu, S AU - Joos, L AU - Roberts, I AU - Nikonorova, N AU - Vu, LD AU - Stes, E AU - Cho, H AU - Larrieu, A AU - Xuan, W AU - Goodall, B AU - van de Cotte, B AU - Waite, JM AU - Rigal, A AU - R Harborough, SR AU - Persiau, G AU - Vanneste, S AU - Kirschner, GK AU - Vandermarliere, E AU - Martens, L AU - Stahl, Y AU - Audenaert, D AU - Friml, Jiří AU - Felix, G AU - Simon, R AU - Bennett, M AU - Bishopp, A AU - De Jaeger, G AU - Ljung, K AU - Kepinski, S AU - Robert, S AU - Nemhauser, J AU - Hwang, I AU - Gevaert, K AU - Beeckman, T AU - De Smet, I ID - 7949 IS - 8 JF - Molecular & Cellular Proteomics TI - The CEP5 peptide promotes abiotic stress tolerance, as revealed by quantitative proteomics, and attenuates the AUX/IAA equilibrium in Arabidopsis VL - 19 ER - TY - JOUR AB - Cell polarity is a fundamental feature of all multicellular organisms. In plants, prominent cell polarity markers are PIN auxin transporters crucial for plant development. To identify novel components involved in cell polarity establishment and maintenance, we carried out a forward genetic screening with PIN2:PIN1-HA;pin2 Arabidopsis plants, which ectopically express predominantly basally localized PIN1 in the root epidermal cells leading to agravitropic root growth. From the screen, we identified the regulator of PIN polarity 12 (repp12) mutation, which restored gravitropic root growth and caused PIN1-HA polarity switch from basal to apical side of root epidermal cells. Complementation experiments established the repp12 causative mutation as an amino acid substitution in Aminophospholipid ATPase3 (ALA3), a phospholipid flippase with predicted function in vesicle formation. ala3 T-DNA mutants show defects in many auxin-regulated processes, in asymmetric auxin distribution and in PIN trafficking. Analysis of quintuple and sextuple mutants confirmed a crucial role of ALA proteins in regulating plant development and in PIN trafficking and polarity. Genetic and physical interaction studies revealed that ALA3 functions together with GNOM and BIG3 ARF GEFs. Taken together, our results identified ALA3 flippase as an important interactor and regulator of ARF GEF functioning in PIN polarity, trafficking and auxin-mediated development. AU - Zhang, Xixi AU - Adamowski, Maciek AU - Marhavá, Petra AU - Tan, Shutang AU - Zhang, Yuzhou AU - Rodriguez Solovey, Lesia AU - Zwiewka, Marta AU - Pukyšová, Vendula AU - Sánchez, Adrià Sans AU - Raxwal, Vivek Kumar AU - Hardtke, Christian S. AU - Nodzynski, Tomasz AU - Friml, Jiří ID - 7619 IS - 5 JF - The Plant Cell SN - 1040-4651 TI - Arabidopsis flippases cooperate with ARF GTPase exchange factors to regulate the trafficking and polarity of PIN auxin transporters VL - 32 ER - TY - JOUR AB - Clathrin-mediated endocytosis (CME) and its core endocytic machinery are evolutionarily conserved across all eukaryotes. In mammals, the heterotetrameric adaptor protein complex-2 (AP-2) sorts plasma membrane (PM) cargoes into vesicles through the recognition of motifs based on tyrosine or di-leucine in their cytoplasmic tails. However, in plants, very little is known on how PM proteins are sorted for CME and whether similar motifs are required. In Arabidopsis thaliana, the brassinosteroid (BR) receptor, BR INSENSITIVE1 (BRI1), undergoes endocytosis that depends on clathrin and AP-2. Here we demonstrate that BRI1 binds directly to the medium AP-2 subunit, AP2M. The cytoplasmic domain of BRI1 contains five putative canonical surface-exposed tyrosine-based endocytic motifs. The tyrosine-to-phenylalanine substitution in Y898KAI reduced BRI1 internalization without affecting its kinase activity. Consistently, plants carrying the BRI1Y898F mutation were hypersensitive to BRs. Our study demonstrates that AP-2-dependent internalization of PM proteins via the recognition of functional tyrosine motifs also operates in plants. AU - Liu, D AU - Kumar, R AU - LAN, Claus AU - Johnson, Alexander J AU - Siao, W AU - Vanhoutte, I AU - Wang, P AU - Bender, KW AU - Yperman, K AU - Martins, S AU - Zhao, X AU - Vert, G AU - Van Damme, D AU - Friml, Jiří AU - Russinova, E ID - 8607 IS - 11 JF - Plant Cell SN - 1040-4651 TI - Endocytosis of BRASSINOSTEROID INSENSITIVE1 is partly driven by a canonical tyrosine-based Motif VL - 32 ER - TY - JOUR AB - The TPLATE complex (TPC) is a key endocytic adaptor protein complex in plants. TPC in Arabidopsis (Arabidopsis thaliana) contains six evolutionarily conserved subunits and two plant-specific subunits, AtEH1/Pan1 and AtEH2/Pan1, although cytoplasmic proteins are not associated with the hexameric subcomplex in the cytoplasm. To investigate the dynamic assembly of the octameric TPC at the plasma membrane (PM), we performed state-of-the-art dual-color live cell imaging at physiological and lowered temperatures. Lowering the temperature slowed down endocytosis, thereby enhancing the temporal resolution of the differential recruitment of endocytic components. Under both normal and lowered temperature conditions, the core TPC subunit TPLATE and the AtEH/Pan1 proteins exhibited simultaneous recruitment at the PM. These results, together with co-localization analysis of different TPC subunits, allow us to conclude that TPC in plant cells is not recruited to the PM sequentially but as an octameric complex. AU - Wang, J AU - Mylle, E AU - Johnson, Alexander J AU - Besbrugge, N AU - De Jaeger, G AU - Friml, Jiří AU - Pleskot, R AU - van Damme, D ID - 7695 IS - 3 JF - Plant Physiology SN - 0032-0889 TI - High temporal resolution reveals simultaneous plasma membrane recruitment of TPLATE complex subunits VL - 183 ER - TY - JOUR AB - Cell production and differentiation for the acquisition of specific functions are key features of living systems. The dynamic network of cellular microtubules provides the necessary platform to accommodate processes associated with the transition of cells through the individual phases of cytogenesis. Here, we show that the plant hormone cytokinin fine‐tunes the activity of the microtubular cytoskeleton during cell differentiation and counteracts microtubular rearrangements driven by the hormone auxin. The endogenous upward gradient of cytokinin activity along the longitudinal growth axis in Arabidopsis thaliana roots correlates with robust rearrangements of the microtubule cytoskeleton in epidermal cells progressing from the proliferative to the differentiation stage. Controlled increases in cytokinin activity result in premature re‐organization of the microtubule network from transversal to an oblique disposition in cells prior to their differentiation, whereas attenuated hormone perception delays cytoskeleton conversion into a configuration typical for differentiated cells. Intriguingly, cytokinin can interfere with microtubules also in animal cells, such as leukocytes, suggesting that a cytokinin‐sensitive control pathway for the microtubular cytoskeleton may be at least partially conserved between plant and animal cells. AU - Montesinos López, Juan C AU - Abuzeineh, A AU - Kopf, Aglaja AU - Juanes Garcia, Alba AU - Ötvös, Krisztina AU - Petrášek, J AU - Sixt, Michael K AU - Benková, Eva ID - 8142 IS - 17 JF - The Embo Journal SN - 0261-4189 TI - Phytohormone cytokinin guides microtubule dynamics during cell progression from proliferative to differentiated stage VL - 39 ER - TY - JOUR AB - Origin and functions of intermittent transitions among sleep stages, including brief awakenings and arousals, constitute a challenge to the current homeostatic framework for sleep regulation, focusing on factors modulating sleep over large time scales. Here we propose that the complex micro-architecture characterizing sleep on scales of seconds and minutes results from intrinsic non-equilibrium critical dynamics. We investigate θ- and δ-wave dynamics in control rats and in rats where the sleep-promoting ventrolateral preoptic nucleus (VLPO) is lesioned (male Sprague-Dawley rats). We demonstrate that bursts in θ and δ cortical rhythms exhibit complex temporal organization, with long-range correlations and robust duality of power-law (θ-bursts, active phase) and exponential-like (δ-bursts, quiescent phase) duration distributions, features typical of non-equilibrium systems self-organizing at criticality. We show that such non-equilibrium behavior relates to anti-correlated coupling between θ- and δ-bursts, persists across a range of time scales, and is independent of the dominant physiologic state; indications of a basic principle in sleep regulation. Further, we find that VLPO lesions lead to a modulation of cortical dynamics resulting in altered dynamical parameters of θ- and δ-bursts and significant reduction in θ–δ coupling. Our empirical findings and model simulations demonstrate that θ–δ coupling is essential for the emerging non-equilibrium critical dynamics observed across the sleep–wake cycle, and indicate that VLPO neurons may have dual role for both sleep and arousal/brief wake activation. The uncovered critical behavior in sleep- and wake-related cortical rhythms indicates a mechanism essential for the micro-architecture of spontaneous sleep-stage and arousal transitions within a novel, non-homeostatic paradigm of sleep regulation. AU - Lombardi, Fabrizio AU - Gómez-Extremera, Manuel AU - Bernaola-Galván, Pedro AU - Vetrivelan, Ramalingam AU - Saper, Clifford B. AU - Scammell, Thomas E. AU - Ivanov, Plamen Ch. ID - 8084 IS - 1 JF - Journal of Neuroscience SN - 0270-6474 TI - Critical dynamics and coupling in bursts of cortical rhythms indicate non-homeostatic mechanism for sleep-stage transitions and dual role of VLPO neurons in both sleep and wake VL - 40 ER -