Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Turf Battle in the Retina Helps Internal Clocks See the Light

07.03.2013
With every sunrise and sunset, our eyes make note of the light as it waxes and wanes, a process that is critical to aligning our circadian rhythms to match the solar day so we are alert during the day and restful at night.

Watching the sun come and go sounds like a peaceful process, but Johns Hopkins scientists have discovered that behind the scenes, millions of specialized cells in our eyes are fighting for their lives to help the retina set the stage to keep our internal clocks ticking.

In a study that appeared in a recent issue of Neuron, a team led by biologist Samer Hattar has found that there is a kind of turf war going on behind our eyeballs, where intrinsically photosensitive retinal ganglion cells (ipRGCs) are jockeying for the best position to receive information from rod and cone cells about light levels. By studying these specialized cells in mice, Hattar and his team found that the cells actually kill each other to seize more space and find the best position to do their job.

Understanding this fight could one day lead to victories against several conditions, including autism and some psychiatric disorders, where neural circuits influence our behavior. The results could help scientists have a better idea about how the circuits behind our eyes assemble to influence our physiological functions, said Hattar, an associate professor of biology in the Krieger School of Arts and Sciences.

"In a nutshell, death in our retina plays a vital role in assembling the retinal circuits that influence crucial physiological functions such as circadian rhythms and sleep-wake cycles," Hattar said. "Once we have a greater understanding of the circuit formation underlying all of our neuronal abilities, this could be applied to any neurological function."

Hattar and his team determined that the killing among rival ipRGCs is justifiable homicide: Without this cell death, circadian blindness overcame the mice, who could no longer distinguish day from night. Hattar’s team studied mice that were genetically modified to prevent cell death by removing the Bax protein, an essential factor for cell death to occur. They discovered that if cell death is prevented, ipRGCs distribution is highly affected, leading the surplus cells to bunch up and form ineffectual, ugly clumps incapable of receiving light information from rods and cones for the alignment of circadian rhythms. To detect this, the researchers used wheel running activity measurements in mice that lacked the Bax protein as well as the melanopsin protein which allows ipRGCs to respond only through rods and cones and compared it to animals where only the Bax gene was deleted.

What the authors uncovered was exciting: When death is prevented, the ability of rods and cones to signal light to our internal clocks is highly impaired. This shows that cell death plays an essential role in setting the circuitry that allows the retinal rods and cones to influence our circadian rhythms and sleep.

Hattar’s study was funded by the National Institute of General Medical Sciences and the National Institute of Neurological Disorders and Stroke and was carried out in close collaboration with Rejji Kuruvilla, an associate professor who is another member of the mouse tri-lab community in the Department of Biology at Johns Hopkins.

Copies of the study are available. Contact Amy Lunday at acl@jhu.edu or 443-287-9960.

Hattar’s webpage: http://www.bio.jhu.edu/Faculty/Hattar/Default.html

Johns Hopkins University news releases can be found on the World Wide Web at http://releases.jhu.edu/

Information on automatic E-mail delivery of science and medical news releases is available at the same address.

Amy Lunday | Newswise
Further information:
http://www.jhu.edu/

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>