2 results
Robust syntaxin-4 immunoreactivity in mammalian horizontal cell processes
- ARLENE A. HIRANO, JOHANN HELMUT BRANDSTÄTTER, ALEJANDRO VILA, NICHOLAS C. BRECHA
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- Journal:
- Visual Neuroscience / Volume 24 / Issue 4 / July 2007
- Published online by Cambridge University Press:
- 20 July 2007, pp. 489-502
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Horizontal cells mediate inhibitory feed-forward and feedback communication in the outer retina; however, mechanisms that underlie transmitter release from mammalian horizontal cells are poorly understood. Toward determining whether the molecular machinery for exocytosis is present in horizontal cells, we investigated the localization of syntaxin-4, a SNARE protein involved in targeting vesicles to the plasma membrane, in mouse, rat, and rabbit retinae using immunocytochemistry. We report robust expression of syntaxin-4 in the outer plexiform layer of all three species. Syntaxin-4 occurred in processes and tips of horizontal cells, with regularly spaced, thicker sandwich-like structures along the processes. Double labeling with syntaxin-4 and calbindin antibodies, a horizontal cell marker, demonstrated syntaxin-4 localization to horizontal cell processes; whereas, double labeling with PKC antibodies, a rod bipolar cell (RBC) marker, showed a lack of co-localization, with syntaxin-4 immunolabeling occurring just distal to RBC dendritic tips. Syntaxin-4 immunolabeling occurred within VGLUT-1-immunoreactive photoreceptor terminals and underneath synaptic ribbons, labeled by CtBP2/RIBEYE antibodies, consistent with localization in invaginating horizontal cell tips at photoreceptor triad synapses. Vertical sections of retina immunostained for syntaxin-4 and peanut agglutinin (PNA) established that the prominent patches of syntaxin-4 immunoreactivity were adjacent to the base of cone pedicles. Horizontal sections through the OPL indicate a one-to-one co-localization of syntaxin-4 densities at likely all cone pedicles, with syntaxin-4 immunoreactivity interdigitating with PNA labeling. Pre-embedding immuno-electron microscopy confirmed the subcellular localization of syntaxin-4 labeling to lateral elements at both rod and cone triad synapses. Finally, co-localization with SNAP-25, a possible binding partner of syntaxin-4, indicated co-expression of these SNARE proteins in the same subcellular compartment of the horizontal cell. Taken together, the strong expression of these two SNARE proteins in the processes and endings of horizontal cells at rod and cone terminals suggests that horizontal cell axons and dendrites are likely sites of exocytotic activity.
The Application of Poly(Phenylene) Type Polymers and Oligomers in Electroluminescent Color Displays
- S. Tasch, C. Brandstätter, W. Graupner, S. Hampel, C. Hochfilzer, J. W. E. List, F. Meghdadi, G. Leising, P. Schlichting, U. Rohr, Y. Geerts, U. Scherf, K. Müllen
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- Journal:
- MRS Online Proceedings Library Archive / Volume 471 / 1997
- Published online by Cambridge University Press:
- 10 February 2011, 325
- Print publication:
- 1997
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Due to their high photoluminescence efficiency (>30%), high environmental stability and the good charge transport properties the derivatives of poly(paraphenylene) (PPP), as the laddertype PPP (LPPP) and the oligomer hexaphenyl, are very suitable materials to realise efficient, stable, large area blue organic light-emitting diodes (OLEDs). The emission of blue OLEDs can be efficiently converted into all other emission colors either by an external color conversion technique (ECCT) or an internal color conversion technique (ICCT) and hence are very interesting for a number of display applications:
Firstly, we demonstrate the realisation of efficient red-green-blue (RGB) emission colors (representing the RGB-pixels in a multicolor display) by an external CCT. In this case the blue EL device is covered with highly fluorescenct dye/matrix layers, which are excited by the blue emission and emit photoluminescence light in a lower energetic range.
Secondly, a new method for producing efficient white light-emitting polymer diodes (which are interesting for e.g. backlight sources in liquid crystal displays) based on a blend of two polymers is presented: a blue light-emitting m-LPPP and a red-orange emitter poly(perylene-co-diethynylbenzene) (PPDB). The red-orange emission is created within the EL device (ICCT) by an excitation energy transfer from m-LPPP into the energetically lower lying states of PPDB. This internal excitation energy transfer is very efficient, so that only a concentration of 0.05 weight % PPDB in the polymer blend is required in order to obtain white light emission.