Colubridae is the largest and most diverse family of snakes, with visual systems that reflect this diversity, encompassing a variety of retinal photoreceptor organizations. The transmutation theory proposed by Walls postulates that photoreceptors could evolutionarily transition between cell types in squamates, but few studies have tested this theory. Recently, evidence for transmutation and rod...

Several mutations in the N terminus of the G-protein-coupled receptor rhodopsin disrupt NXS/T consensus sequences for N-linked glycosylation (located at N2 and N15) and cause sector retinitis pigmentosa in which the inferior retina preferentially degenerates. Here we examined the role of rhodopsin glycosylation in biosynthesis, trafficking, and retinal degeneration (RD) using transgenic Xenopus...

Rhodopsin is a photoreceptive protein present in vertebrate rod photoreceptor cells, which are responsible for scotopic vision. Recent molecular studies have shown that several aquatic vertebrate species have independently acquired rhodopsin containing Asp83Asn, Glu122Gln, and Ala292Ser substitutions, causing a blue shift in the rhodopsin absorption spectra for adaptation to the blue-green phot...

Endogenous circadian clocks regulate day-night rhythms of animal behavior and physiology. In zebrafish, the circadian clocks are located in the pineal gland and the retina. In the retina, each photoreceptor is considered a circadian oscillator. A critical question is whether the individual circadian oscillators are synchronized. If so, the mechanism that underlies the synchronization needs to b...

PURPOSE To investigate the pathogenic mechanisms that underlie retinal degeneration induced by the rhodopsin mutation P23H in a Xenopus laevis model of RP. METHODS Transgenic X. laevis were generated that expressed the rhodopsin mutants rhoP23H and rhoP23H/K29R (a variant incapable of transducin activation). Using quantitative dot blot assay, transgenic rhodopsin levels and the extent of reti...

PURPOSE To explore further the potential role autoimmunity may play in the pathogenesis of normal-pressure glaucoma (NPG) in some patients, the authors examined the sera of patients with NPG for the presence of antibodies directed toward retinal antigens. METHODS Using patient sera, immunoblotting was performed on subcellular fractions of retina, purified bovine rhodopsin, and immunoaffinity-...

Previously we have shown that a subset of visual transduction mutants in Drosophila melanogaster induce the formation of stable complexes between rhodopsin and arrestin. One such mutant is in a visual system-specific phospholipase C (PLC). The rhodopsin/arrestin complexes generated in PLC mutants induce massive retinal degeneration. Here we demonstrate that both arrestin and rhodopsin undergo l...

The maintenance of photoreceptor cell polarity is compromised by the rhodopsin mutations causing the human disease autosomal dominant retinitis pigmentosa. The severe form mutations occur in the C-terminal sorting signal of rhodopsin, VXPX-COOH. Here, we report that this sorting motif binds specifically to the small GTPase ARF4, a member of the ARF family of membrane budding and protein sorting...

The light-sensing organelle of the vertebrate rod photoreceptor, the outer segment (OS), is a modified cilium containing approximately 1,000 stacked disc membranes that are densely packed with visual pigment rhodopsin. The mammalian OS is renewed every ten days; new discs are assembled at the base of the OS by a poorly understood mechanism. Our results suggest that discs are formed and matured ...

Rhodopsin density and absolute threshold were determined in 11 patients with retinitis pigmentosa (RP) and nine normal subjects. In eight patients with familial histories suggesting recessive inheritance, the retinal areas studied showed marked decrease in sensitivity which was related to rhodopsin loss, probably via a log-linear relationship. The other three patients showed absolute thresholds...