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 Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care

nachricht Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>