31 research outputs found

    Signaling pathways controlling activity-dependent local translation of BDNF and their localization in dendritic arbors

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    4noBrain-derived neurotrophic factor (BDNF) is encoded by multiple mRNA variants whose differential subcellular distribution constitutes a "spatial code" for local translation of BDNF and selective morphological remodeling of dendrites. Here, we investigated where BDNF translation takes place and what are the signaling pathways involved. Cultured hippocampal neurons, treated with KCl showed increased BDNF in the soma, proximal and distal dendrites even in quaternary branches. Activity-dependent increase of BDNF is abolished by cycloheximide, suggesting local translation, and requires activation of glutamate and Trk receptors. Our data show that BDNF translation is regulated by multiple signaling cascades including RAS/Erk and mTOR pathways, CaMKII/CPEB1, Aurora-A/CPEB1 and Src/ZBP1 pathways. Aurora-A, CPEB1, ZBP1, eiF4E, S6 are present throughout the dendritic arbor. Neuronal activity increases Aurora-A, CPEB1, ZBP1 levels in distal dendrites while eiF4E, S6 are unaffected. BDNF-6, the main dendritic BDNF transcript, is translated in the same subcellular domains and in response to the same pathways as total BDNF. In conclusion, we identified the signaling cascades controlling BDNF translation and we describe how their localization is modulated in response to electrical activity.partially_openopenBaj, G; Pinhero, V; Vaghi, V; Tongiorgi, EBaj, G; Pinhero, V; Vaghi, V; Tongiorgi,

    Stability of casein micelles cross-linked with genipin: a physicochemical study as a function of pH

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    Chemical or enzymatic cross-linking of casein micelles (CMs) increases their stability against dissociating agents. In this paper, a comparative study of stability between native CMs and CMs cross-linked with genipin (CMs-GP) as a function of pH is described. Stability to temperature and ethanol were investigated in the pH range 2.0-7.0. The size and the charge (ζ\zeta-potential) of the particles were determined by dynamic light scattering. Native CMs precipitated below pH 5.5, CMs-GP precipitated from pH 3.5 to 4.5, whereas no precipitation was observed at pH 2.0-3.0 or pH 4.5-7.0. The isoelectric point of CMs-GP was determined to be pH 3.7. Highest stability against heat and ethanol was observed for CMs-GP at pH 2, where visible coagulation was determined only after 800 s at 140 ∘^\circC or 87.5% (v/v) of ethanol. These results confirmed the hypothesis that cross-linking by GP increased the stability of CMs.Comment: 5 pages, 2 figures, International Dairy Journal, 201

    Electronic structure of quasicrystalline surfaces: Effects of surface preparation and bulk structure

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    We elucidate the nature of the surface electronic properties of quasicrystalline Al-Pd-Mn. We do this by using photoelectron and Auger electron spectroscopies, and by making a variety of comparisons—across types of bulk samples, and across methods of surface preparation. The main conclusions are these: (i) The narrow Mn 2p3/2core-level line observed in the icosahedral phase is a fingerprint of a suppression in the density of states (a pseudogap) at the Fermi level and is not unique to the quasicrystalline phase. It is also independent of the symmetry of the quasicrystalline surface. The Auger line shape is also affected and may be used as a fingerprint of a pseudogap. (ii) A similarly narrow Fe 2p3/2 core-level line characterizes the icosahedral Al-Cu-Fe quasicrystal, consistent with the expectation that the electronic structure is of general importance in the stabilization of icosahedral phases. (iii) In icosahedral Al-Pd-Mn, the pseudogap of the bulk is not retained up to the surface immediately after fracture, but can be restored by annealing, or by sputter annealing to sufficiently high temperatures. Assuming that the pseudogap reflects an electronic stabilization of the atomic structure, these results suggest that the heat-treated surfaces are more stable than the surface obtained by fracturing at room temperature

    Perceived Surface Slant Is Systematically Biased in the Actively-Generated Optic Flow

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    Humans make systematic errors in the 3D interpretation of the optic flow in both passive and active vision. These systematic distortions can be predicted by a biologically-inspired model which disregards self-motion information resulting from head movements (Caudek, Fantoni, & Domini 2011). Here, we tested two predictions of this model: (1) A plane that is stationary in an earth-fixed reference frame will be perceived as changing its slant if the movement of the observer's head causes a variation of the optic flow; (2) a surface that rotates in an earth-fixed reference frame will be perceived to be stationary, if the surface rotation is appropriately yoked to the head movement so as to generate a variation of the surface slant but not of the optic flow. Both predictions were corroborated by two experiments in which observers judged the perceived slant of a random-dot planar surface during egomotion. We found qualitatively similar biases for monocular and binocular viewing of the simulated surfaces, although, in principle, the simultaneous presence of disparity and motion cues allows for a veridical recovery of surface slant

    Electronic structure of quasicrystalline surfaces: Effects of surface preparation and bulk structure

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    We elucidate the nature of the surface electronic properties of quasicrystalline Al-Pd-Mn. We do this by using photoelectron and Auger electron spectroscopies, and by making a variety of comparisons—across types of bulk samples, and across methods of surface preparation. The main conclusions are these: (i) The narrow Mn 2p3/2core-level line observed in the icosahedral phase is a fingerprint of a suppression in the density of states (a pseudogap) at the Fermi level and is not unique to the quasicrystalline phase. It is also independent of the symmetry of the quasicrystalline surface. The Auger line shape is also affected and may be used as a fingerprint of a pseudogap. (ii) A similarly narrow Fe 2p3/2 core-level line characterizes the icosahedral Al-Cu-Fe quasicrystal, consistent with the expectation that the electronic structure is of general importance in the stabilization of icosahedral phases. (iii) In icosahedral Al-Pd-Mn, the pseudogap of the bulk is not retained up to the surface immediately after fracture, but can be restored by annealing, or by sputter annealing to sufficiently high temperatures. Assuming that the pseudogap reflects an electronic stabilization of the atomic structure, these results suggest that the heat-treated surfaces are more stable than the surface obtained by fracturing at room temperature.This article is from Physical Review B 62, no. 21 (2000): 14049–14060, doi:10.1103/PhysRevB.62.14049.</p
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