Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Loss of fruit fly retina protein delays blinding light damage

17.12.2004


In experiments with fruit flies, Johns Hopkins researchers have found that blindness induced by constant light results directly from the loss of a key light-detecting protein, rather than from the overall death of cells in the retina, which in humans is a light-sensitive tissue at the back of the eye.

The research, reported in the Dec. 14 issue of Current Biology, overturns the long-standing belief that blindness from chronic light exposure is a direct result of overall retinal degeneration and cell death.

Although many animals, and presumably humans, lose both their retinal cells and vision after exposure to low levels of light for long periods, the relationship between exposure and blindness had been poorly understood.



In the Hopkins experiments, flies whose light-detecting protein rhodopsin was engineered to resist destruction retained their vision twice as long as normal flies, although over time they developed blindness due to delayed decay of rhodopsin. The researchers measured vision damage indirectly by measuring loss of the electrical signals normally initiated by rhodopsin when exposed to light.

"Everyone assumed that the blindness caused by chronic light exposure was an effect of the degeneration and loss of the retinal cells, but our experiments show these are two distinct events caused by two distinct processes," says Craig Montell, Ph.D., professor of biological chemistry in Hopkins’ Institute for Basic Biomedical Sciences. "Understanding how degradation of rhodopsin and other visual proteins contributes to vision loss may help us in the future to reduce the severity of blindness in rare people susceptible to chronic exposure to light."

The light-detecting cells of fruit fly retinas share similarities with rod and cone cells of the human retina and also rely on rhodopsin to detect light and create an electrical signal that is transmitted to the brain.

In the researchers’ experiments, this electrical signal was measured by a tool called an electroretinogram, which uses a contact placed on the surface of the eye. The measured signals get smaller as the flies lose their ability to see.

The researchers used the electroretinogram on normal fruit flies and found that these flies lost both their sight and some retinal cells after nine days of exposure, as expected. The researchers also found that rhodopsin levels were drastically lower after three days of exposure and virtually gone by day 13.

In genetically engineered flies whose rhodopsin destruction was inhibited in various ways, the researchers found no or relatively minor loss of the light-induced signal until much later. Other flies whose rhodopsin destruction had been genetically accelerated went blind twice as fast as normal flies. "We were quite surprised - we thought we’d prove correct what scientists had assumed was happening, but instead we proved that long-held idea wrong," says Montell.

Remarkably, the earliest vision loss in normal flies was reversible for up to three days of light exposure, says Montell. But after three days, when the eyes’ electrical signals were halved, the eyes reached a point of no return and vision never fully recovered. This point should be longer for other animals, since fruitflies’ lifespan is only about 50 days.

The researchers are now searching for other proteins that reduce or prevent vision loss after exposure to constant light. They’re also studying how constant light causes irreversible destruction of rhodopsin.

Joanna Downer | EurekAlert!
Further information:
http://www.current-biology.com/
http://www.jhmi.edu

More articles from Life Sciences:

nachricht During HIV infection, antibody can block B cells from fighting pathogens
14.08.2018 | NIH/National Institute of Allergy and Infectious Diseases

nachricht First study on physical properties of giant cancer cells may inform new treatments
14.08.2018 | Brown 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: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>