ScienceDaily (Oct. 10, 2008) — DNA, the molecule that acts as the carrier of genetic information in all forms of life, is highly resistant against alteration by ultraviolet light, but understanding the mechanism for its photostability presents some puzzling problems. A key aspect is the interaction between the four chemical bases that make up the DNA molecule. Researchers at Kiel University have succeeded in showing that DNA strands differ in their light sensitivity depending on their base sequences.