Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Brown Scientists Uncover Inner Workings of Rare Eye Cells

27.01.2005


A Brown University team has found that a protein called melanopsin plays a key role in the inner workings of mysterious, spidery cells in the eye called intrinsically photosensitive retinal ganglion cells, or ipRGCs.


Visual clues to daily rhythms - Intrinsically photosensitive retinal ganglion cells – ipRGCs, right – were discovered in 2002. New research shows that the protein melanopsin enables ipRGCs to do their job of setting the body’s master circadian clock. It may be an extremely ancient system in terms of evolution, researchers say.



Melanopsin, they found, absorbs light and triggers a biochemical cascade that allows the cells to signal the brain about brightness. Through these signals, ipRGCs synchronize the body’s daily rhythms to the rising and setting of the sun. This circadian rhythm controls alertness, sleep, hormone production, body temperature and organ function. Brown researchers, led by neuroscientist David Berson, announced the discovery of ipRGCs in 2002. Their work was astonishing: Rods and cones aren’t the only light-sensitive eye cells.

Like rods and cones, ipRGCs turn light energy into electrical signals. But while rods and cones aid sight by detecting objects, colors and movement, ipRGCs gauge overall light intensity. Numbering only about 1,000 to 2,000 out of millions of eyes cells, ipRGCs are different in another way: They have a direct link to brain, sending a message to the tiny region that controls the body clock about how light or dark the environment is. The cells are also responsible for narrowing the pupil of the eye.


“It’s a general brightness detection system in the eye,” said Berson, the Sidney A. Fox and Dorothea Doctors Fox Professor of Ophthalmology and Visual Sciences. “What we’ve done now is provide more details about how this system works.”

The research, published in the current issue of Nature, provides the first evidence that melanopsin is a functional sensory photopigment. In other words, this protein absorbs light and sets off a chain of chemical reactions in a cell that triggers an electrical response. The study also showed that melanopsin plays this role in ganglion-cell photoreceptors, helping them send a powerful signal to the brain that it is day or night.

The team made the discovery by inserting melanopsin into cells taken from the kidneys and grown in culture. These cells, which are not normally sensitive to light, were transformed into photoreceptors when flooded with melanopsin. In fact, the kidney cells responded to light almost exactly the way ipRGCs do, confirming that melanopsin is the photopigment for ganglion-cell photoreceptors. “This resolves a key question about the function of these cells,” Berson said. “And so little is known about them, anything we learn is important.”

Berson and his team made another intriguing finding: The biochemical cascade sparked by melanopsin is closer to that of eye cells in invertebrates like fruit flies and squid than in spined animals such as mice, monkeys or humans. “The results may well tell us that this is an extremely ancient system in terms of evolution,” Berson said. “We may have a bit of the invertebrate in our eyes.”

The research team from Brown included lead author and post-doctoral research associate Xudong Qiu and post-doctoral research associate Kwoon Wong, both in the Department of Neuroscience, as well as graduate students Stephanie Carlson and Vanitha Krishna in the Neuroscience Graduate Program. Tida Kumbalasiri and Ignacio Provencio from the Uniformed Services University of the Health Sciences also contributed to the research.

The National Institutes of Health funded the work.

Wendy Lawton | EurekAlert!
Further information:
http://www.brown.edu

More articles from Life Sciences:

nachricht Microscope measures muscle weakness
16.11.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht Good preparation is half the digestion
16.11.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>