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Tuesday / July 16.
HomeminewsFruit Flies Fight Retinal Degeneration

Fruit Flies Fight Retinal Degeneration

Research by Johns Hopkins sensory biologists has found that the simple fruit fly can help humans who suffer retinal dystrophies.

The study has revealed a critical step in fly vision which manifest as visual defects ranging from mild visual impairments to complete blindness.

The article, published in Current Biology paves the way for using the fruit fly to screen for therapies to treat human retinal degeneration.

Retinal dystrophies result from inherited defects in nearly every step of the so-called “visual cycle,” a series of biochemical reactions known to occur in vertebrates, which recycles the molecule that enables light detection in eye cells. “Therapeutic approaches to tackle such retinal dystrophies are very limited,” says Professor Craig Montell.

“So it’s useful to take advantage of simpler experimental model organisms, like fruit flies, to tease apart complex systems like vision, then translate that to use in vertebrates.”

Curious about whether one particular enzyme in the fly eye – pigment-cell-enriched dehydrogenase (PDH) – played a role in the fly’s ability to make the molecules that sense light, Montell and his research team generated flies carrying a mutation in the gene encoding PDH. They found the newly hatched flies lacking PDH to be totally normal in their ability to respond to light.

“It was a surprise. Initially the PDH looked dispensable as the visual responses were normal, but over time the pigment degraded,” says Montell. “This led us to ask the question: If PDH doesn’t make new light-sensing molecules, and flies can recycle them using light anyway, why are these flies losing their light-detecting molecules and consequently their sight?”

Montell’s team found PDH was required to help recycle the used light-capturing molecules in a previously unrecognized visual cycle in flies. Flies can recycle the molecules by absorbing light, but eventually the protein that holds the molecules in the cells needs to be replaced with new protein. When this happens the biochemical visual cycle is needed to regenerate the light sensing molecules. Over time, in PDH mutant flies, without a functional visual cycle, the used light-sensitive molecules were not regenerated causing cells in the retina to die, leading to vision loss.

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