scholarly journals Some properties of old and new rhodopsin in single Bufo rods.

1984 ◽  
Vol 83 (6) ◽  
pp. 841-852 ◽  
Author(s):  
T P Williams
Keyword(s):  
Absorption Spectrum ◽  
Lateral Diffusion ◽  
Major Protein ◽  
Rod Photoreceptors ◽  
Outer Segments ◽  
Point Of Entry ◽  
Diffusion Rates ◽  
Insight Into ◽  
Bleached State

Rod photoreceptors renew the membranous disks of the outer segments (ROS). New disks are assembled at the proximal base and old disks are shed at the distal tip. Rhodopsin, the major protein of the disk, remains with the disk into which it was inserted. Thus, it is true that the oldest rhodopsin is at the tip and the newest at the base. A microspectrophotometer is used to examine the properties of rhodopsin in the two ends of the toad ROS. No differences between the two are found in absorption spectrum, concentration, dichroism, photoconversion rates, or lateral diffusion rates. Regeneration of rhodopsin from the bleached state is also studied but cannot be used to discriminate old from new rhodopsin because the point of entry of regeneration retinoids and/or their concentrations cannot be controlled. However, a new insight into pigment regeneration in the living toad eye is gained: regeneration is faster in the basal disks than in the distal.

The 1D4 Antibody Labels Outer Segments of Long Double Cone But Not Rod Photoreceptors in Zebrafish

2012 ◽  
Vol 53 (8) ◽  
pp. 4943 ◽  
Author(s):  
Jun Yin ◽  
Jan Brocher ◽  
Bastian Linder ◽  
Anja Hirmer ◽  
Husvinee Sundaramurthi ◽  
...  
Keyword(s):  
Double Cone ◽  
Rod Photoreceptors ◽  
Outer Segments

scholarly journals Reduction of All-trans Retinal to All-trans Retinol in the Outer Segments of Frog and Mouse Rod Photoreceptors

2005 ◽  
Vol 88 (3) ◽  
pp. 2278-2287 ◽  
Author(s):  
Chunhe Chen ◽  
Efthymia Tsina ◽  
M. Carter Cornwall ◽  
Rosalie K. Crouch ◽  
Sukumar Vijayaraghavan ◽  
...  
Keyword(s):  
Rod Photoreceptors ◽  
Outer Segments

The ageing photoreceptor

2007 ◽  
Vol 24 (2) ◽  
pp. 151-155 ◽  
Author(s):  
ALEXANDER CUNEA ◽  
GLEN JEFFERY
Keyword(s):  
Aging Process ◽  
Outer Segment ◽  
Retinal Disease ◽  
Segment Length ◽  
Rod Photoreceptor ◽  
Retinal Neurons ◽  
Rod Photoreceptors ◽  
Outer Segments ◽  
Age Related ◽  
Similar Density

With age many retinal neurons are lost. In humans the rod photoreceptor population in the perimacular region is subject to approximately 30% loss over life. Those that remain have been reported to suffer from extensive convolutions and localized swellings of their outer segments abnormally increasing their disc content and outer segment length. Here we examine quantitatively age-related changes in rat rod photoreceptors. The rat retina is ∼97% rod dominated. Here, aged rods showed significant reductions in outer segment length. The discs in their outer segments had a similar density, irrespective of whether they were young or old, however, in aged animals a higher proportion were misregistered. Surprisingly, in all of the tissue examined, we found no evidence for any convolution of outer segments or localized swelling as reported in humans, rather all remained straight. There are methodological differences between the research reported here and that undertaken on human retinae. There are also major differences in overall retinal architecture between humans and rodents that could contribute to differences in the aging process of individual cells. If it is the case that individual photoreceptors age differently in rodents compared to humans, it may pose significant problems for the use of this animal model in studies of ageing and age related outer retinal disease.

scholarly journals Benzylchlorocarbene: UV Absorption Spectrum, Kinetics for 1,2-H Migration and Mechanism for Reaction With Acetic Acid as Determined by Combined Continuous and Laser-Flash Photolysis

1990 ◽  
Vol 10 (5-6) ◽  
pp. 267-275 ◽  
Author(s):  
R. Bonneau ◽  
M. T. H. Liu ◽  
R. Subramanian ◽  
B. Linkletter ◽  
I. D. R. Stevens
Keyword(s):  
Absorption Spectrum ◽  
Acetic Acid ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Uv Absorption ◽  
Quenching Rate ◽  
Continuous Irradiation ◽  
Insight Into ◽  
Uv Absorption Spectrum

The UV absorption spectrum of benzylchlorocarbene, generated by laser flash photolysis of 3-chloro-3- benzyldiazirine, has been observed in the 290-330 nm range. The lifetime of this species, 18 ns at 25°C, is determined by the rate of the 1,2-H migration to produce chlorostyrenes. Quenching rate constants of this carbene by acetic acid and tetramethylethylene have been measured. Comparison of this kinetic data with the quantitative analysis of the products obtained under continuous irradiation gives further insight into the mechanisms of carbene-acetic acid reactions.

scholarly journals Rates of membrane-associated reactions: reduction of dimensionality revisited.

1986 ◽  
Vol 102 (1) ◽  
pp. 88-96 ◽  
Author(s):  
M A McCloskey ◽  
M M Poo
Keyword(s):  
Lateral Diffusion ◽  
Reduced Dimensionality ◽  
Intracellular Membranes ◽  
Reduction Of Dimensionality ◽  
Diffusion Rates ◽  
Substrate Affinities

The hypothesis that reactions associated with intracellular membranes enjoy a kinetic advantage from a reduced dimensionality for diffusion is inconsistent with available data on lateral diffusion rates, membrane-substrate affinities, and endogenous concentrations of enzymes and their aqueous substrates.

Retinal development of West Australian dhufish, Glaucosoma hebraicum

2001 ◽  
Vol 18 (5) ◽  
pp. 711-724 ◽  
Author(s):  
JULIA SHAND ◽  
MICHAEL A. ARCHER ◽  
NICOLE THOMAS ◽  
JENNIFER CLEARY
Keyword(s):  
Ganglion Cell ◽  
Ganglion Cell Layer ◽  
Light And Electron Microscopy ◽  
Low Light ◽  
Exogenous Feeding ◽  
Rod Photoreceptors ◽  
Outer Segments ◽  
Light Levels ◽  
Single Cone ◽  
Area Centralis

An investigation of retinal specializations was carried out in larval and juvenile dhufish, Glaucosoma hebraicum (Glaucosomidae, Teleostei). The development of photoreceptors and formation of the retinal mosaic was followed by light and electron microscopy. At hatching the eye was undifferentiated. Cone photoreceptors were present by day 3 posthatch (dph), when exogenous feeding began. Single and multiple cones were present in a row arrangement from 3 dph to 20 dph, when the first rod nuclei were observed. Between 20 dph and approximately 3 months posthatch (mph), the row arrangement was replaced by a square mosaic of four double cones surrounding a single cone, and the cones increased in size, with the outer segments reaching up to 30 μm in length. During the period of spatial rearrangement, triple cones were often observed. From their first appearance, rod photoreceptors were added rapidly. Investigation of ganglion cell topography in 3-mph fish that had attained the adult-like square photoreceptor mosaic was carried out using retinal wholemounts. The highest densities of neurones in the ganglion cell layer were in temporal retina but no well-defined area centralis was observed. Microspectrophotometric measurements of the visual pigments within the outer segments of the photoreceptors of 3-mph fish revealed double cones with identical absorption spectra in each member of the outer segment, and the wavelength of maximum absorption (λmax) located at 522 nm. Single cones were found to possess a visual pigment with λmax at 460 nm and rods with a λmax of 498 nm. The results imply that the larvae and juveniles are adapted for survival in coastal waters and may be active in relatively low light levels from early stages of development.

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