TY - JOUR AB - Extrasynaptic actions of glutamate are limited by high-affinity transporters expressed by perisynaptic astroglial processes (PAPs): this helps maintain point-to-point transmission in excitatory circuits. Memory formation in the brain is associated with synaptic remodeling, but how this affects PAPs and therefore extrasynaptic glutamate actions is poorly understood. Here, we used advanced imaging methods, in situ and in vivo, to find that a classical synaptic memory mechanism, long-term potentiation (LTP), triggers withdrawal of PAPs from potentiated synapses. Optical glutamate sensors combined with patch-clamp and 3D molecular localization reveal that LTP induction thus prompts spatial retreat of astroglial glutamate transporters, boosting glutamate spillover and NMDA-receptor-mediated inter-synaptic cross-talk. The LTP-triggered PAP withdrawal involves NKCC1 transporters and the actin-controlling protein cofilin but does not depend on major Ca2+-dependent cascades in astrocytes. We have therefore uncovered a mechanism by which a memory trace at one synapse could alter signal handling by multiple neighboring connections. AU - Henneberger, Christian AU - Bard, Lucie AU - Panatier, Aude AU - Reynolds, James P. AU - Kopach, Olga AU - Medvedev, Nikolay I. AU - Minge, Daniel AU - Herde, Michel K. AU - Anders, Stefanie AU - Kraev, Igor AU - Heller, Janosch P. AU - Rama, Sylvain AU - Zheng, Kaiyu AU - Jensen, Thomas P. AU - Sanchez-Romero, Inmaculada AU - Jackson, Colin J. AU - Janovjak, Harald L AU - Ottersen, Ole Petter AU - Nagelhus, Erlend Arnulf AU - Oliet, Stephane H.R. AU - Stewart, Michael G. AU - Nägerl, U. VAlentin AU - Rusakov, Dmitri A. ID - 8674 IS - 5 JF - Neuron SN - 08966273 TI - LTP induction boosts glutamate spillover by driving withdrawal of perisynaptic astroglia VL - 108 ER - TY - JOUR AB - Nature creates electrons with two values of the spin projection quantum number. In certain applications, it is important to filter electrons with one spin projection from the rest. Such filtering is not trivial, since spin-dependent interactions are often weak, and cannot lead to any substantial effect. Here we propose an efficient spin filter based upon scattering from a two-dimensional crystal, which is made of aligned point magnets. The polarization of the outgoing electron flux is controlled by the crystal, and reaches maximum at specific values of the parameters. In our scheme, polarization increase is accompanied by higher reflectivity of the crystal. High transmission is feasible in scattering from a quantum cavity made of two crystals. Our findings can be used for studies of low-energy spin-dependent scattering from two-dimensional ordered structures made of magnetic atoms or aligned chiral molecules. AU - Ghazaryan, Areg AU - Lemeshko, Mikhail AU - Volosniev, Artem ID - 8652 JF - Communications Physics SN - 2399-3650 TI - Filtering spins by scattering from a lattice of point magnets VL - 3 ER - TY - JOUR AB - Pancreatic islets play an essential role in regulating blood glucose level. Although the molecular pathways underlying islet cell differentiation are beginning to be resolved, the cellular basis of islet morphogenesis and fate allocation remain unclear. By combining unbiased and targeted lineage tracing, we address the events leading to islet formation in the mouse. From the statistical analysis of clones induced at multiple embryonic timepoints, here we show that, during the secondary transition, islet formation involves the aggregation of multiple equipotent endocrine progenitors that transition from a phase of stochastic amplification by cell division into a phase of sublineage restriction and limited islet fission. Together, these results explain quantitatively the heterogeneous size distribution and degree of polyclonality of maturing islets, as well as dispersion of progenitors within and between islets. Further, our results show that, during the secondary transition, α- and β-cells are generated in a contemporary manner. Together, these findings provide insight into the cellular basis of islet development. AU - Sznurkowska, Magdalena K. AU - Hannezo, Edouard B AU - Azzarelli, Roberta AU - Chatzeli, Lemonia AU - Ikeda, Tatsuro AU - Yoshida, Shosei AU - Philpott, Anna AU - Simons, Benjamin D ID - 8669 JF - Nature Communications TI - Tracing the cellular basis of islet specification in mouse pancreas VL - 11 ER - TY - JOUR AB - Cell fate transitions are key to development and homeostasis. It is thus essential to understand the cellular mechanisms controlling fate transitions. Cell division has been implicated in fate decisions in many stem cell types, including neuronal and epithelial progenitors. In other stem cells, such as embryonic stem (ES) cells, the role of division remains unclear. Here, we show that exit from naive pluripotency in mouse ES cells generally occurs after a division. We further show that exit timing is strongly correlated between sister cells, which remain connected by cytoplasmic bridges long after division, and that bridge abscission progressively accelerates as cells exit naive pluripotency. Finally, interfering with abscission impairs naive pluripotency exit, and artificially inducing abscission accelerates it. Altogether, our data indicate that a switch in the division machinery leading to faster abscission regulates pluripotency exit. Our study identifies abscission as a key cellular process coupling cell division to fate transitions. AU - Chaigne, Agathe AU - Labouesse, Céline AU - White, Ian J. AU - Agnew, Meghan AU - Hannezo, Edouard B AU - Chalut, Kevin J. AU - Paluch, Ewa K. ID - 8672 IS - 2 JF - Developmental Cell SN - 15345807 TI - Abscission couples cell division to embryonic stem cell fate VL - 55 ER - TY - JOUR AB - In the computation of the material properties of random alloys, the method of 'special quasirandom structures' attempts to approximate the properties of the alloy on a finite volume with higher accuracy by replicating certain statistics of the random atomic lattice in the finite volume as accurately as possible. In the present work, we provide a rigorous justification for a variant of this method in the framework of the Thomas–Fermi–von Weizsäcker (TFW) model. Our approach is based on a recent analysis of a related variance reduction method in stochastic homogenization of linear elliptic PDEs and the locality properties of the TFW model. Concerning the latter, we extend an exponential locality result by Nazar and Ortner to include point charges, a result that may be of independent interest. AU - Fischer, Julian L AU - Kniely, Michael ID - 8697 IS - 11 JF - Nonlinearity SN - 09517715 TI - Variance reduction for effective energies of random lattices in the Thomas-Fermi-von Weizsäcker model VL - 33 ER -