April 16, 2009
A secret to night vision found in DNA
German-led scientists say they have discovered an important element of DNA that creates good night vision in nocturnal mammals.
Ludwig-Maximilians University researchers in Munich said they discovered the DNA within the photoreceptor rod cells responsible for low light vision turns the rod cell nuclei themselves into tiny light-collecting lenses, with millions of them in every nocturnal eye.
The conventional architecture seen in almost all nuclei is invariably present in the rod cells of diurnal mammals, including primates, pigs and squirrels, said researcher Boris Joffe.
On the other hand, the unique inverted architecture is universally present in nocturnal mammals.
That architecture has important ramifications for the optical properties of those cells, said Jochen Guck of the University of Cambridge.
Diurnal nuclei are basically scattering obstacles, he said.
In nocturnal animals, they are little lenses. In one case, light is scattered in all directions and in the other it is focused in the forward direction, meaning that even at night, what little light there is can travel deeper into the eye where it can be perceived.
The research is detailed in the journal Cell.