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 New technique unveils 'matrix' inside tissues and tumors
29.06.2017 | University of Copenhagen The Faculty of Health and Medical Sciences

nachricht Designed proteins to treat muscular dystrophy
29.06.2017 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making Waves

Computer scientists use wave packet theory to develop realistic, detailed water wave simulations in real time. Their results will be presented at this year’s SIGGRAPH conference.

Think about the last time you were at a lake, river, or the ocean. Remember the ripples of the water, the waves crashing against the rocks, the wake following...

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Nanostructures taste the rainbow

29.06.2017 | Physics and Astronomy

New technique unveils 'matrix' inside tissues and tumors

29.06.2017 | Life Sciences

Cystic fibrosis alters the structure of mucus in airways

29.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>