A new study discovered that fish and other amphibians turn to a Vitamin A-related enzyme to see through murky waters, red lights and infrared lights - an ability that resembles that of superheroes with x-ray vision.
For close to a hundred years, experts have been baffled as to how freshwater fish and amphibians smoothly adapt their vision from blue-green-lighted terrestrial or marine areas to inland stream waters. In streams, algae, mud and other objects, light is filtered out from the blue part of the spectrum thus forming a light environment that changes to the red/infrared of the spectrum.
In their new study, the experts discovered that these animals have the ability to turn on an enzyme in the eye that lets it see through infrared light, which is present in murky freshwater environments like streams and rivers. The enzyme was identified as Cyp27c1, which is said to be a relative of vitamin A - a substance recognized to promote good eyesight, especially in low light.
Vitamin A is a vital element of eye pigments that ease sight. Therefore, having the ability to stimulate the release of substance that closely resembles vitamin A is a great help for amphibians to match their vision to the light currently present.
Cyp27c1 initiates a minimal molecular alteration to vitamin A1 and changes it to vitamin A2, which enables the species to shift the sensitivity of its photoreceptors to longer wavelengths like red and infrared lights.
"For example, when salmon migrate from the ocean to inland streams, they turn on this enzyme, activating a chemical reaction that shifts the visual system, helping the fish peer more deeply into murky water," explained Joseph Corbo, the senior author of the study.
"We don't know when in the course of evolution the Cyp27c1 enzyme first acquired the function it has today," said Corbo. He added, however, that the reality that the same substance is utilized by both amphibians and fish proposes that this ability may have existed hundred millions of years back.
The research was published in the journal Current Biology on Thursday, Nov. 5.
Photo: U.S. Department of Agriculture | Flickr