The activity of O6-methylguanine DNA methyl-transferase in livers of ducks from Qidong and Qingpu

O6-methylguanine DNA methyltransferase (O6-AT) is an enzyme for the repair of the promutagenic structure, O6-alkylguanine, from alkylated DNA, therefore low activity of O6-AT is involved in the predisposition of tissues to some nitrosamines and the development of cancer. The levels of O6-AT in livers of ducks from Qidong (Qd), a high incidence area of liver cancer, and from Qingpu(Qp), a relatively low incidence area were determined in this study. The results showed that the activity of O6-AT was higher in Qp than in Qd. It suggested that some nitrosamine in Qd might be one of factors responsible for the higher incidence of ducks liver cancer, because these ducks were more sensitive to nitrosamine.