UV-induced skin cancers have a known link to DNA damage. Now scientists in France say the damage can be better understood by looking at how DNA components relax after exposure to light. 

DNA bases are the only DNA components that can be electronically excited by the sun's UV radiation, said Clélia Canuel at the Commissariat à l'énergie atomique (CEA) Saclay. Using a technique called time-resolved spectroscopy, Canuel and colleagues have worked out how a derivative of the DNA base adenine loses the energy it absorbs when exposed to UV light.

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For the adenine derivative, 'we found an ultra-fast two step relaxation mechanism,' said Canuel. This 'probably prevents chemical reactions in the excited states and mutation introduction,' continued Canuel, meaning that the adenine is quite stable when exposed to UV light.

Clusters of the adenine derivative and water were also studied, to bridge the gap between isolated molecules and biological environments, explained Canuel. The team found that the base remained stable even when interacting with water. 

The researchers will now use the same methods to study the other DNA bases affected by UV radiation: guanine, cytosine and thymine. They plan to examine the bases in isolation and in water clusters, before looking at adenine-thymine and guanine-cytosine pairs.

Susan Batten