Navigation Links
Finding is a feather in the cap for researchers studying birds' big, powerful eyes
Date:6/23/2011

BETHESDA, Md., June 23, 2011 Say what you will about bird brains, but our feathered friends sure have us -- and all the other animals on the planet -- beat in the vision department, and that has a bit to do with how their brains develop.

Consider the in-flight feats of birds of prey: They must spot their dinner from long distances and dive-bomb those moving targets at lightning speed. And then there are the owls, which operate nimbly on even the darkest nights to secure supper in swift swoops. Some birds have ultraviolet sensitivity; others have infrared sensitivity. To boot, some birds can even see the Earth's magnetic field.

Much of the credit for avian visual acuity goes to the extraordinary retina, which grows out of the brain during development, making it an official component of the central nervous system. Indeed, the avian retina is far more complex in structure and composition than the human retina, and it contains many more photoreceptors -- rod- and cone-shaped cells that detect light and color, respectively.

While researchers over the years have come to better understand much about the avian retina, many nagging questions remain. For Thorsten Burmester's research team at the University of Hamburg, the question was this: How does such a productive retina sustain itself when the avian eye has very few capillaries to deliver oxygen to it? After all, it has to "breathe," so to speak.

"The visual process in the vertebrate eye requires high amounts of metabolic energy and thus oxygen," Burmester's group writes in this week's Journal of Biological Chemistry. "Oxygen supply of the avian retina is a challenging task because birds have large eyes, thick retinas and high metabolic rates, but neither deep retinal nor superficial capillaries."

To answer the question, Burmester's team took a closer look at a protein that they discovered exists in large quantities in photoreceptor cells of the avian eye -- and only of the avian eye. They named the protein globin E. (The "E" is short for "eye," of course.)

Burmester's team used a number of techniques to characterize globin E and found that it is responsible for storing and delivering oxygen to the retina.

The finding is intriguing for a number of reasons.

Firstly, it helps explain how birds evolved to have such large eyes, relative to their body mass, without a dense network of ocular capillaries for blood delivery. (Some owls, for instance, have bigger eyes than humans.)

"The exact origin of globin E is still somewhat a mystery," Burmester said. "It clearly evolved from some type of globin, but it has no obvious relative outside the birds."

The globins are all thought to share a common ancestor, and the most well-known members of the family are myoglobin and hemoglobin. Myoglobin is responsible for oxygen storage and release in heart and skeletal muscle fibers. Hemoglobin, meanwhile, transports oxygen from the lungs to other parts of the body in red blood cells.

Burmester explains: "Bird eyes have evolved to have a system not unlike those in our heart, which uses myoglobin to store and release oxygen to maintain respiration and energy-consumption during muscle contraction. In eyes, oxygen and energy are needed to generate neuronal signals."

Secondly, the finding puts to rest an earlier hypothesis that another molecule, neuroglobin, might be the oxygen-delivery vehicle for the avian eye. Neuroglobin is known to deliver oxygen to brain tissue, so it was only natural to suspect it. But it turns out that the messenger RNA fingerprint of globin E was 100-fold more prevalent than that of neuroglobin in Burmester's chicken retina samples, indicating that neuroglobin probably has another, yet-to-be defined function in the avian eye.

Lastly, globin E is another interesting illustration of the convergent evolution of "myoglobin-like" molecules. Among the organisms with proteins with similar functions are the soybean, which needs its leghemoglobin to deliver oxygen to the Rhizobium soil bacteria that colonize in root nodules, and the 2-foot-long sea worm Cerebratulus lacteus, which needs its mini-hemoglobin to keep its brain and neurons oxygenated when it burrows deep into the sea floor, where oxygen levels are low, in search of clams.


'/>"/>

Contact: Angela Hopp
ahopp@asbmb.org
240-283-6614
American Society for Biochemistry and Molecular Biology
Source:Eurekalert

Related biology news :

1. Plant pathologist finding Kansas wheat fields a molecular battleground this season
2. Researchers improve method for finding genetic mistakes that fuel cancer
3. Surprising findings from studies of spontaneous brain activity
4. Rochester autism researchers present new findings at IMFAR
5. TGen findings contribute to understanding of diabetic kidney disease
6. Findings may help keep pancreatic disease off the menu
7. Finding shows potential way to protect neurons in Parkinsons, Alzheimers, ALS
8. Finding a way to extend tomato shelf-life
9. Saint Louis University findings: Dont pitch stockpiled avian flu vaccine
10. New findings in Indias Bt cotton controversy: Good for the field, bad for the farm?
11. New findings provide cost, benefit data for Florida citrus industry
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/22/2016)... 22, 2016 On Monday, the Department of ... to share solutions for the Biometric Exit Program. The ... Border Protection (CBP), explains that CBP intends to add ... the United States , in order to ... imposters. Logo - http://photos.prnewswire.com/prnh/20160622/382209LOGO ...
(Date:6/16/2016)... The global Biometric ... USD 1.83 billion by 2024, according to a ... proliferation and increasing demand in commercial buildings, consumer ... the market growth.      (Logo: ... of advanced multimodal techniques for biometric authentication and ...
(Date:6/9/2016)... , June 9, 2016 ... deploy Teleste,s video security solution to ensure the safety of ... during the major tournament Teleste, an ... systems and services, announced today that its video security solution ... to back up public safety across the country. The ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... 2016  Liquid Biotech USA ... a Sponsored Research Agreement with The University of ... from cancer patients.  The funding will be used ... with clinical outcomes in cancer patients undergoing a ... be employed to support the design of a ...
(Date:6/24/2016)... June 24, 2016 Epic Sciences unveiled ... cancers susceptible to PARP inhibitors by targeting homologous ... (CTCs). The new test has already been incorporated ... multiple cancer types. Over 230 clinical ... response pathways, including PARP, ATM, ATR, DNA-PK and ...
(Date:6/23/2016)... ... June 23, 2016 , ... Mosio, ... second eBook, “Clinical Trials Patient Recruitment and Retention Tips.” Partnering with experienced clinical ... eBook by providing practical tips, tools, and strategies for clinical researchers. , “The ...
(Date:6/23/2016)... 23, 2016 /PRNewswire/ - FACIT has announced the ... biotechnology company, Propellon Therapeutics Inc. ("Propellon" or ... of a portfolio of first-in-class WDR5 inhibitors for ... as WDR5 represent an exciting class of therapies, ... medicine for cancer patients. Substantial advances have been ...
Breaking Biology Technology: