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 Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>