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https://www.readbyqxmd.com/read/28921532/the-morphological-characterization-of-orientation-biased-displaced-large-field-ganglion-cells-in-the-central-part-of-goldfish-retina
#1
Hideo Hoshi, Fumi Sato
The vertebrate retina has about 30 subtypes of ganglion cells. Each ganglion cell receives synaptic inputs from specific types of bipolar and amacrine cells ramifying at the same depth of the inner plexiform layer (IPL), each of which is thought to process a specific aspect of visual information. Here, we identified one type of displaced ganglion cell in the goldfish retina which had a large and elongated dendritic field. As a population, all of these ganglion cells were oriented in the horizontal axis and perpendicular to the dorsal-ventral axis of the goldfish eye in the central part of retina...
September 18, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28915323/hair-cell-transduction-tuning-and-synaptic-transmission-in-the-mammalian-cochlea
#2
Robert Fettiplace
Sound pressure fluctuations striking the ear are conveyed to the cochlea, where they vibrate the basilar membrane on which sit hair cells, the mechanoreceptors of the inner ear. Recordings of hair cell electrical responses have shown that they transduce sound via submicrometer deflections of their hair bundles, which are arrays of interconnected stereocilia containing the mechanoelectrical transducer (MET) channels. MET channels are activated by tension in extracellular tip links bridging adjacent stereocilia, and they can respond within microseconds to nanometer displacements of the bundle, facilitated by multiple processes of Ca2+-dependent adaptation...
September 12, 2017: Comprehensive Physiology
https://www.readbyqxmd.com/read/28874522/efficient-stimulus-secretion-coupling-at-ribbon-synapses-requires-rim-binding-protein-tethering-of-l-type-ca-2-channels
#3
Fujun Luo, Xinran Liu, Thomas C Südhof, Claudio Acuna
Fast neurotransmitter release from ribbon synapses via Ca(2+)-triggered exocytosis requires tight coupling of L-type Ca(2+) channels to release-ready synaptic vesicles at the presynaptic active zone, which is localized at the base of the ribbon. Here, we used genetic, electrophysiological, and ultrastructural analyses to probe the architecture of ribbon synapses by perturbing the function of RIM-binding proteins (RBPs) as central active-zone scaffolding molecules. We found that genetic deletion of RBP1 and RBP2 did not impair synapse ultrastructure of ribbon-type synapses formed between rod bipolar cells (RBCs) and amacrine type-2 (AII) cells in the mouse retina but dramatically reduced the density of presynaptic Ca(2+) channels, decreased and desynchronized evoked neurotransmitter release, and rendered evoked and spontaneous neurotransmitter release sensitive to the slow Ca(2+) buffer EGTA...
September 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28863864/two-pools-of-vesicles-associated-with-synaptic-ribbons-are-molecularly-prepared-for-release
#4
Proleta Datta, Jared Gilliam, Wallace B Thoreson, Roger Janz, Ruth Heidelberger
Neurons that form ribbon-style synapses are specialized for continuous exocytosis. To this end, their synaptic terminals contain numerous synaptic vesicles, some of which are ribbon associated, that have difference susceptibilities for undergoing Ca(2+)-dependent exocytosis. In this study, we probed the relationship between previously defined vesicle populations and determined their fusion competency with respect to SNARE complex formation. We found that both the rapidly releasing vesicle pool and the releasable vesicle pool of the retinal bipolar cell are situated at the ribbon-style active zones, where they functionally interact...
August 29, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28827351/mechanisms-of-synaptic-depression-at-the-hair-cell-ribbon-synapse-that-support-auditory-nerve-function
#5
Juan D Goutman
Inner hair cells (IHCs) in the cochlea are the mammalian phono-receptors, transducing sound energy into graded changes in membrane potentials, the so called "receptor potentials." Ribbon synapses between IHCs and auditory nerve neurons are responsible for converting receptor potentials into spike rates. The characteristics of auditory nerve responses to sound have been described extensively. For instance, persistent acoustic stimulation produces sensory adaptation, which is revealed as a reduction in neuronal spike rate with time constants in the range of milliseconds to seconds...
August 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28811255/cortical-layers-cyto-myelo-receptor-and-synaptic-architecture-in-human-cortical-areas
#6
REVIEW
Nicola Palomero-Gallagher, Karl Zilles
Cortical layers have classically been identified by their distinctive and prevailing cell types and sizes, as well as the packing densities of cell bodies or myelinated fibers. The densities of multiple receptors for classical neurotransmitters also vary across the depth of the cortical ribbon, and thus determine the neurochemical properties of cyto- and myeloarchitectonic layers. However, a systematic comparison of the correlations between these histologically definable layers and the laminar distribution of transmitter receptors is currently lacking...
August 12, 2017: NeuroImage
https://www.readbyqxmd.com/read/28790889/the-calcineurin-binding-activity-dependent-splice-variant-dynamin1xb-is-highly-enriched-in-synapses-in-various-regions-of-the-central-nervous-system
#7
Marie-Lisa Eich, Ekta Dembla, Silke Wahl, Mayur Dembla, Karin Schwarz, Frank Schmitz
In the present study, we generated and characterized a splice site-specific monoclonal antibody that selectively detects the calcineurin-binding dynamin1 splice variant dynamin1xb. Calcineurin is a Ca(2+)-regulated phosphatase that enhances dynamin1 activity and is an important Ca(2+)-sensing mediator of homeostatic synaptic plasticity in neurons. Using this dynamin1xb-specific antibody, we found dynamin1xb highly enriched in synapses of all analyzed brain regions. In photoreceptor ribbon synapses, dynamin1xb was enriched in close vicinity to the synaptic ribbon in a manner indicative of a peri-active zone immunolabeling...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28744553/brag2a-a-guanine-nucleotide-exchange-factor-for-arf6-is-a-component-of-the-dystrophin-associated-glycoprotein-complex-at-the-photoreceptor-terminal
#8
Hiroyuki Sakagami, Osamu Katsumata, Yoshinobu Hara, Toshikuni Sasaoka, Masahiro Fukaya
Purpose: Mutations in genes encoding the dystrophin-associated glycoprotein complex (DGC) can cause muscular dystrophy and disturb synaptic transmission in the photoreceptor ribbon synapse. However, the molecular composition and specific functions of the photoreceptor DGC remain unknown. Brefeldin A-resistant Arf-GEF 2 (BRAG2), also known as IQSEC1, is a guanine nucleotide exchange factor for ADP-ribosylation factor 6 (Arf6), a critical GTPase that regulates endosomal trafficking and actin cytoskeleton remodeling...
July 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28744203/synaptic-ribbon-active-zones-in-cone-photoreceptors-operate-independently-from-one-another
#9
Justin J Grassmeyer, Wallace B Thoreson
Cone photoreceptors depolarize in darkness to release glutamate-laden synaptic vesicles. Essential to release is the synaptic ribbon, a structure that helps organize active zones by clustering vesicles near proteins that mediate exocytosis, including voltage-gated Ca(2+) channels. Cone terminals have many ribbon-style active zones at which second-order neurons receive input. We asked whether there are functionally significant differences in local Ca(2+) influx among ribbons in individual cones. We combined confocal Ca(2+) imaging to measure Ca(2+) influx at individual ribbons and patch clamp recordings to record whole-cell ICa in salamander cones...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28743939/a-cryosectioning-technique-for-the-observation-of-intracellular-structures-and-immunocytochemistry-of-tissues-in-atomic-force-microscopy-afm
#10
Eiji Usukura, Akihiro Narita, Akira Yagi, Nobuaki Sakai, Yoshitsugu Uekusa, Yuka Imaoka, Shuichi Ito, Jiro Usukura
The use of cryosectioning facilitates the morphological analysis and immunocytochemistry of cells in tissues in atomic force microscopy (AFM). The cantilever can access all parts of a tissue sample in cryosections after the embedding medium (sucrose) has been replaced with phosphate-buffered saline (PBS), and this approach has enabled the production of a type of high-resolution image. The images resembled those obtained from freeze-etching replica electron microscopy (EM) rather than from thin-section EM. The AFM images showed disks stacked and enveloped by the cell membrane in rod photoreceptor outer segments (ROS) at EM resolution...
July 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28701482/analysis-of-rim-expression-and-function-at-mouse-photoreceptor-ribbon-synapses
#11
Martina Löhner, Norbert Babai, Tanja Müller, Kaspar Gierke, Jenny Atorf, Anneka Joachimsthaler, Angela Peukert, Henrik Martens, Andreas Feigenspan, Jan Kremers, Susanne Schoch, Johann Helmut Brandstätter, Hanna Regus-Leidig
RAB3A-interacting molecule (RIM) proteins are important regulators of transmitter release from active zones. At conventional chemical synapses, RIMs contribute substantially to vesicle priming and docking and their loss reduces the readily releasable pool of synaptic vesicles by up to 75%. The priming function of RIMs is mediated via the formation of a tripartite complex with Munc13 and RAB3A, which brings synaptic vesicles in close proximity to Ca(2+) channels and the fusion site and activates Munc13. We reported previously that, at mouse photoreceptor ribbon synapses, vesicle priming is Munc13 independent...
August 16, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28641988/wavy-multistratified-amacrine-cells-in-the-monkey-retina-contain-immunoreactive-secretoneurin
#12
Andrea S Bordt, Ye Long, Nobuo Kouyama, Elizabeth S Yamada, Jens Hannibal, David W Marshak
The goals of this study were to describe the morphology, neurotransmitter content and synaptic connections of neurons in primate retinas that contain the neuropeptide secretoneurin. Amacrine cells were labeled with antibodies to secretoneurin in macaque and baboon retinas. Their processes formed three distinct plexuses in the inner plexiform layer: one in the outermost stratum, one in the center and one in the innermost stratum. In light microscopic double immunolabeling experiments, GABA was colocalized with secretoneurin in these cells, but glycine transporter 1 and Substance P were not...
August 2017: Peptides
https://www.readbyqxmd.com/read/28612046/shaping-of-signal-transmission-at-the-photoreceptor-synapse-by-eaat2-glutamate-transporters
#13
Stephanie Niklaus, Lucia Cadetti, Colette M Vom Berg-Maurer, André Lehnherr, Adriana L Hotz, Ian C Forster, Matthias Gesemann, Stephan C F Neuhauss
Photoreceptor ribbon synapses tonically release glutamate. To ensure efficient signal transmission and prevent glutamate toxicity, a highly efficient glutamate removal system provided by members of the SLC1 gene family is required. By using a combination of biophysical and in vivo studies, we elucidate the role of excitatory amino acid transporter 2 (EAAT2) proteins in synaptic glutamate homeostasis at the zebrafish photoreceptor synapse. The main glutamate sink is provided by the glial EAAT2a, reflected by reduced electroretinographic responses in EAAT2a-depleted larvae...
May 2017: ENeuro
https://www.readbyqxmd.com/read/28576729/afferent-synaptogenesis-between-ectopic-hair-cell-like-cells-and-neurites-of-spiral-ganglion-induced-by-atoh1-in-mammals-in-vitro
#14
Wen-Wei Luo, Rui Ma, Xiang Cheng, Xiao-Yu Yang, Zhao Han, Dong-Dong Ren, Ping Chen, Fang-Lu Chi, Juan-Mei Yang
Newly formed ectopic hair-cell-like cells (EHCLCs) induced by overexpression of atonal homolog 1 (Atoh1) in vitro were found to possess features of endogenous hair cells (HCs) in previous reports and in the present study. However, limited information is available regarding whether EHCLCs and native spiral ganglion neurons (SGNs) form afferent synapses, which are important for the restoration of hearing. In the current study, we focused on the afferent synaptogenesis between EHCLCs and SGN-derived dendrites...
May 31, 2017: Neuroscience
https://www.readbyqxmd.com/read/28546313/enlargement-of-ribbons-in-zebrafish-hair-cells-increases-calcium-currents-but-disrupts-afferent-spontaneous-activity-and-timing-of-stimulus-onset
#15
Lavinia Sheets, Xinyi J He, Jennifer Olt, Mary Schreck, Ronald S Petralia, Ya-Xian Wang, Qiuxiang Zhang, Alisha Beirl, Teresa Nicolson, Walter Marcotti, Josef G Trapani, Katie S Kindt
In sensory hair cells of auditory and vestibular organs, the ribbon synapse is required for the precise encoding of a wide range of complex stimuli. Hair cells have a unique presynaptic structure, the synaptic ribbon, which organizes both synaptic vesicles and calcium channels at the active zone. Previous work has shown that hair-cell ribbon size is correlated with differences in postsynaptic activity. However, additional variability in postsynapse size presents a challenge to determining the specific role of ribbon size in sensory encoding...
June 28, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28396597/photoreceptor-outer-segment-like-structures-in-long-term-3d-retinas-from-human-pluripotent-stem-cells
#16
Karl J Wahlin, Julien A Maruotti, Srinivasa R Sripathi, John Ball, Juan M Angueyra, Catherine Kim, Rhonda Grebe, Wei Li, Bryan W Jones, Donald J Zack
The retinal degenerative diseases, which together constitute a leading cause of hereditary blindness worldwide, are largely untreatable. Development of reliable methods to culture complex retinal tissues from human pluripotent stem cells (hPSCs) could offer a means to study human retinal development, provide a platform to investigate the mechanisms of retinal degeneration and screen for neuroprotective compounds, and provide the basis for cell-based therapeutic strategies. In this study, we describe an in vitro method by which hPSCs can be differentiated into 3D retinas with at least some important features reminiscent of a mature retina, including exuberant outgrowth of outer segment-like structures and synaptic ribbons, photoreceptor neurotransmitter expression, and membrane conductances and synaptic vesicle release properties consistent with possible photoreceptor synaptic function...
April 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28378516/how-do-horizontal-cells-talk-to-cone-photoreceptors-different-levels-of-complexity-at-the-cone-horizontal-cell-synapse
#17
Camille A Chapot, Thomas Euler, Timm Schubert
The first synapse of the retina plays a fundamental role in the visual system. Due to its importance, it is critical that it encodes information from the outside world with the greatest accuracy and precision possible. Cone photoreceptor axon terminals contain many individual synaptic sites, each represented by a presynaptic structure called a 'ribbon'. These synapses are both highly sophisticated and conserved. Each ribbon relays the light signal to one ON cone bipolar cell and several OFF cone bipolar cells, while two dendritic processes from a GABAergic interneuron, the horizontal cell, modulate the cone output via parallel feedback mechanisms...
August 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28363980/a-presynaptic-group-iii-mglur-recruits-g%C3%AE-%C3%AE-snare-interactions-to-inhibit-synaptic-transmission-by-cone-photoreceptors-in-the-vertebrate-retina
#18
Matthew J Van Hook, Norbert Babai, Zack Zurawski, Yun Young Yim, Heidi E Hamm, Wallace B Thoreson
G-protein βγ subunits (Gβγ) interact with presynaptic proteins and regulate neurotransmitter release downstream of Ca(2+) influx. To accomplish their roles in sensory signaling, photoreceptor synapses use specialized presynaptic proteins that support neurotransmission at active zone structures known as ribbons. While several G-protein coupled receptors (GPCRs) influence synaptic transmission at ribbon synapses of cones and other retinal neurons, it is unknown whether Gβγ contributes to these effects. We tested whether activation of one particular GPCR, a metabotropic glutamate receptor (mGluR), can reduce cone synaptic transmission via Gβγ in tiger salamander retinas...
April 26, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28361374/spatial-gradients-in-the-size-of-inner-hair-cell-ribbons-emerge-before-the-onset-of-hearing-in-rats
#19
Radha Kalluri, Maya Monges-Hernandez
The size and locations of pre-synaptic ribbons and glutamate receptors within and around inner hair cells are correlated with auditory afferent response features such as the spontaneous discharge rate (SR), threshold, and dynamic range of sound intensity representation (the so-called SR-groups). To test if the development of these spatial gradients requires experience with sound intensity, we quantified the size and spatial distribution of synaptic ribbons from the inner hair cells of neonatal rats before and after the onset of hearing (from post-natal day (P) 3 to P33)...
June 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/28334377/lrit3-differentially-affects-connectivity-and-synaptic-transmission-of-cones-to-on-and-off-bipolar-cells
#20
Marion Neuillé, Yan Cao, Romain Caplette, Debbie Guerrero-Given, Connon Thomas, Naomi Kamasawa, José-Alain Sahel, Christian P Hamel, Isabelle Audo, Serge Picaud, Kirill A Martemyanov, Christina Zeitz
Purpose: Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). Using a cCSNB mouse model lacking Lrit3 (nob6), we recently have shown that LRIT3 has a role in the correct localization of TRPM1 (transient receptor potential melastatin 1) to the dendritic tips of ON-bipolar cells (BCs), contacting both rod and cone photoreceptors. Furthermore, postsynaptic clustering of other mGluR6 cascade components is selectively eliminated at the dendritic tips of cone ON-BCs...
March 1, 2017: Investigative Ophthalmology & Visual Science
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