Researchers in the Netherlands have found a way to observe directly the damaging effects of ultraviolet radiation on skin cells in animal models. The work suggests that even small amounts of ultraviolet radiation can cause a large number of mutations in skin cell DNA and that gradual exposure did not help resistance to the damage.
A bacteria gene was inserted in a mouse and the animal was then exposed to UV light. The gene was removed and inserted into another bacteria which was encouraged to grow. Damage to DNA was detectable by noting the colour of the growing bacterial colony, blue for normal, white for damage.