Long before sunglasses came on the scene, animals had evolved ways, such as shutter-like irises, to deal with the large differences in lighting that their eyes encounter. After all, many animals can see on both a starry night and a sunny day.
Two research teams have now uncovered a novel molecular mechanism that assists animals' vision. Proteins that are central to the complex light-sensing systems of the eye migrate from one part of a retinal cell to another to adjust the cell's sensitivity.
"This is a new theme" in light adaptation, says Vadim Arshavsky of Harvard Medical School in Boston, an author of one of the reports that appear in the March 28 Neuron.
Mammalian eyes depend on rods and cones, retinal cells known as photoreceptors. These cells sport protein complexes that respond to light by creating an electrical signal that travels to the brain. When photons hit a light-sensing protein called rhodopsin, another protein–transducin–amplif