Research sheds light on how we see in the dark
Researchers in Hong Kong have found a protein in the visual systems of animals and insects that could give a better understanding of human ailments such as night blindness.
The protein, called INAD, operates like a switch and regulates the reception of the brightness and dimness of light by modulating the sensitivity of photoreceptors in the eye.
Zhang Mingjie, chair profess or life sciences at the University of Science and Technology, who led the study said: 'Under dim light, the reduced INAD protein keeps the visual system at the highest sensitivity for light detection.
'Increasing light intensities proportionally convert INAD and tune down the signal-receiving sensitivity of photoreceptors.'
The research explains how animals see in dim light and react quickly to danger. Zhang added: 'Our discovery will help doctors to understand better the origins of diseases.
'Drug manufacturers can develop new products in that direction.'
The six-year study is published in the latest issue of the journal Cell as the cover article.
What was remarkable, said Zhang, was that photoreceptors are able to react over a wide range of brightness and darkness in tens of milliseconds rather than seconds.
'It would mean disaster if it took up to a few seconds or longer for a person to respond to an approaching car on the road or for a fly to react to a fly swatter,' he said.
He said the study into how INAD was regulated - involving processes called oxidation and acidity - would lead to a new class of drugs and better understanding of diseases.
'With our discovery, drug companies will be able to develop another class of drugs that operate on a brand new mechanism,' Zhang said.
Night blindness is the inability to see well at night or in poor light.
It is not a disorder in itself, but a symptom of an underlying disorder or problem, especially untreated nearsightedness.