| DNA ligase encircles the double helix |
to repair a broken strand of DNA
The collaborators from San Francisco were comparing normal mice to genetically modified mice that mimic Alzheimers and were initially surprised to find the DSB's in normal mice. However, after an initial rise in DSB's the levels began to decrease suggesting that a cycle of damage and repair is normal in the learning process. In contrast, the modified mice had higher initial levels of DSB's which rose when exposed to a new environment but were decreased more slowly. So while some formation of DSB's is normal, if the levels are not decreased permanent damage could result.