Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Vision researchers find that photon receptors pair up in neat rows

27.01.2003


Using atomic-force microscopy, vision researchers have taken pictures of some of the eye’s photon receptors in their natural state, and have analyzed their packing arrangement. Their findings, published in the Jan. 9 issue of Nature, offer insight on how light signaling might be controlled in the retina’s outer edge.


THE WELL-ORGANIZED EYE: This close up, high-magnification image of the disc membrane on a rod from the retina shows protrusions lined up in neat, double rows like eggs in a carton. The protrusions are a paracrystal form of rhodopsin, a light absorbing chemical.



The retina receives light through rods and cones. Rods, which are most heavily concentrated on the retina’s outer edge, are sensitive to dim light and to movement, but not to color. Rods, like cones, face away from incoming light. Within rods, light causes a chemical reaction with rhodopsin. This begins a chain of stimulation along the visual pathway, which sends information to the brain for interpretation. The brain can detect one photon of light, the smallest unit of energy, when it is absorbed by a photoreceptor.

The outer segment of a rod looks roughly like a stack of microscopic coins inside a wrapping. The segment is made up of discs covered by a membrane. Scientists studying the retina knew that the outer-segment disc membranes of rods are densely packed with rhodopsin molecules. This bunching together allows for optimum absorption of dim light and for subsequent amplification of the faint signal by the visual pathway. However, how rhodopsin molecules are physically arranged to increase the probability of being activated by a photon was not known.


In the Nature study, scientists looked at outer-segment disc membranes taken from rods in mouse retinae. Their collection method preserved the biological activity and organization of rhodopsin in the membranes. Atomic-force microscopy revealed that much of the surface of the membrane was markedly textured with narrow-ruled lines. At high magnification, researchers could see rhodopsin pairs appearing as tidy double rows of protrusions. They had the regularity of eggs in a carton.

Earlier, scientists conducting biochemical and pharmacological analyses had proposed that similar receptors were arranged in this manner. The recent demonstration that rhodopsin molecules pair in tight, neat lines is consistent with those inferences.

This particular organization of signaling molecules has important implications for recognition of particular proteins, binding, signal amplification, and signal termination. The shape and dimensions of the cell set stringent boundaries for this type of physical configuration, for contacts between the paired units, and for formation of larger structures consisting of these units.

The researchers on this study were Drs. Dimitrios Fotiadis and Andreas Engel of the M.E. Muller Institute for Microscopy, Biozentrum, University of Basel, Switzerland; and University of Washington researchers Drs. Yan Liang, Slawomir Filipek, and David Saperstein from the Department of Ophthalmology, and Dr. Krzysztof Palczewski, who is the Bishop Professor of Ophthalmology and also holds appointments in pharmacology and chemistry.

Leila Gray | EurekAlert!
Further information:
http://www.washington.edu/

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>