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We tested whether calcium-induced calcium release (CICR) contributes to synaptic release from rods in mammalian retina. Electron micrographs and immunofluorescent double labeling for the sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA2) and synaptic ribbon protein, ribeye, showed a close association between ER and synaptic ribbons in mouse rod terminals.(More)
In vision, balance and hearing, sensory receptor cells translate sensory stimuli into electrical signals whose amplitude is graded with stimulus intensity. The output synapses of these sensory neurons must provide fast signaling to follow rapidly changing stimuli while also transmitting graded information covering a wide range of stimulus intensity and must(More)
Retinal prosthetic devices are being developed to bypass degenerated retinal photoreceptors by directly activating retinal neurons with electrical stimulation. However, the retinal circuitry that is activated by epiretinal stimulation is not well characterized. Whole-cell patch clamp recordings were obtained from ganglion cells in normal and rd mice using(More)
Retinal horizontal cells (HCs) provide negative feedback to cones, but, largely because annular illumination fails to evoke a depolarizing response in rods, it is widely believed that there is no feedback from HCs to rods. However, feedback from HCs to cones involves small changes in the calcium current (I(Ca)) that do not always generate detectable(More)
We tested whether horizontal cells (HCs) provide feedback that regulates the Ca(2+) current (I(Ca)) of rods in salamander and mouse retinas. In both species, hyperpolarizing HCs by puffing a glutamate antagonist, 6,7-dinitro-quinoxaline-2,3-dione (DNQX), onto HC processes caused a negative shift in the voltage dependence of rod I(Ca) and increased its peak(More)
The localization and density of voltage-gated Ca(2+) channels at active zones are essential for the amount and kinetics of transmitter release at synapses. RIM proteins are scaffolding proteins at the active zone that bind to several other presynaptic proteins, including voltage-gated Ca(2+) channel α-subunits. The long isoforms of RIM proteins, which(More)
Cones release glutamate-filled vesicles continuously in darkness, and changing illumination modulates this release. Because sustained release in darkness is governed by vesicle replenishment rates, we analyzed how cone membrane potential regulates replenishment. Synaptic release from cones was measured by recording postsynaptic currents in Ambystoma(More)
Various Synaptotagmin (Syt) isoform genes are found in mammals, but it is unknown whether Syts can function redundantly in a given nerve terminal, or whether isoforms can be switched during the development of a nerve terminal. Here, we investigated the possibility of a developmental Syt isoform switch using the calyx of Held as a model synapse. At mature(More)
The direct reprogramming of somatic cells to a pluripotent state holds significant implications for treating intractable degenerative diseases by ex vivo cell therapy. In addition, the reprogrammed cells can serve as a model for diseases and the discovery of drugs and genes. Here, we demonstrate that mouse fibroblast induced pluripotent stem cells (iPSCs)(More)
Structural features of neurons create challenges for effective production and distribution of essential metabolic energy. We investigated how metabolic energy is distributed between cellular compartments in photoreceptors. In avascular retinas, aerobic production of energy occurs only in mitochondria that are located centrally within the photoreceptor. Our(More)