Dependence of induction of clustered DNA damage on radiation track structure

Yokoya, Akinari; O'Neill, P.*

Most mechanistic studies of clustered DNA damage to date have focused on the yields of clustered damage induced by low- and high-LET radiation, using base excision repair proteins as enzymatic probes to detect base lesions or AP sites. We present the dependence of the yields of clustered DNA damage on radiation track structure, previously studied using plasmids as simple model DNA or genomic DNA in mammalian cells. We also note that the enzymatic method have some technical difficulties to detect base lesions in a cluster because of the enzymatic efficiency reduction. Some new techniques, such as DNA denaturation treatment, have been applied to overcome this problem. These new experimental evidences will also be presented, and compared with in vitro data of repairability of artificial clusters incorporated into oligonucleotides.