When every photon counts
The eyes of nocturnal mammals contain particularly large numbers of the highly light-sensitive rods, the photoreceptor type used for night vision. This allows the detection of light levels millions of times lower than daylight. Researchers at the Ludwig Maximilians University Munich, the Max Planck Institute for Brain Research Frankfurt and the Cavendish Laboratory Cambridge have now shown that the nocturnal lifestyle and its visual challenges had a unique impact on rod nuclear organisation: The distributions of the densely packed inactive and the less densely packed active regions of DNA differ remarkably from those in other somatic cells of nearly all organisms from protozoans to multicellular animals, including the rods of diurnal mammals.