To gain insight into the genetic mechanisms of photoreceptor development, we analyzed a collection of zebrafish mutations characterized by early photoreceptor cell loss. The mutant defects impair outer segment formation and are accompanied by an abnormal distribution of visual pigments. Rods and different cone types display defects of similar severity suggesting that genetic pathways common to ...

PURPOSE To compare the changes in visually guided performance as a function of age between Royal College of Surgeons (RCS) dystrophic and congenic rats and to correlate photoreceptor cell number with visually guided performance in age-matched populations of RCS dystrophic rats. METHODS The visually guided performances of RCS dystrophic (n=6) and congenic (n=7) rats were studied from 0.75 to 1...

OBJECTIVE To determine whether methylprednisolone or indomethacin can enhance photoreceptor survival after laser retinal injury in an animal model. DESIGN Experimental study. PARTICIPANTS Twenty rhesus monkeys. METHODS Twenty rhesus monkeys (Macaca mulatta) received a grid of argon green (514.5 nm, 10 ms) laser lesions in the macula of the right eye and a grid of neodymium:yttrium-aluminu...

The sensory basis ofmagnetoreception in animals still remains amystery. One hypothesis ofmagnetoreception is that photochemical radical pair reactions can transducemagnetic information in specialized photoreceptor cells, possibly involving the photoreceptor molecule cryptochrome. This hypothesis triggered a considerable amount of research in the past decade. Here, we present an updated picture ...

For determination of possible neurotransmitters synthesized by photoreceptor cells, turtle retinas were dissociated into single cells with proteolytic enzymes. These cells were partially separated by velocity sedimentation to yield a fraction rich in photoreceptors. Individual photoreceptor cells were then sucked into a micropipette and incubated with labeled precursors of known or suspected ne...

Zinc is associated with glutamatergic pathways in brain and retina, yet its role in neuromodulation remains unknown. High concentrations of reactive zinc in vertebrate photoreceptor terminals suggest a neuromodulatory role in the outer plexiform layer but zinc release has not been demonstrated. Using the membrane-impermeable form of the Zn(2+) sensitive fluorescent dye Newport Green, we have de...

The transport of the photopigment rhodopsin from the inner segment to the photosensitive outer segment of vertebrate photoreceptor cells has been one of the main remaining mysteries in photoreceptor cell biology. Because of the lack of any direct evidence for the pathway through the photoreceptor cilium, alternative extracellular pathways have been proposed. Our primary aim in the present study...

The remarkable ability of our vision to function under ever-changing conditions of ambient illumination is mediated by multiple molecular mechanisms regulating the light sensitivity of rods and cones. One such mechanism involves massive translocation of signaling proteins, including the G-protein transducin, into and out of the light-sensitive photoreceptor outer segment compartment. Transducin...

The fractal spectrum of magnetic minibands (Hofstadter butterfly), induced by the moiré superlattice of graphene on a hexagonal crystal substrate, is known to exhibit gapped Dirac cones. We show that the gap can be closed by slightly misaligning the substrate, producing a hierarchy of conical singularities (Dirac points) in the band structure at rational values Φ = (p/q)(h/e) of the magnetic fl...

Photoreceptor cell death is the hallmark of a group of human inherited retinal degeneration. Although the causative genetic mutations are often known, the mechanisms leading to photoreceptor degeneration remain poorly defined. Here, we show that Semaphorin 4A (Sema4A), a member of axonal guidance molecule semaphorin, plays a role in Rab11/FIP2-mediated endosomal sorting in retinal pigment epith...