Abstract
We irradiated third instar larvae of fruit fly, Drosophila melanogaster with X-rays, and carried out the somatic mutation and recombination test (SMART). When wild-type flies were irradiated with 0.2Gy, mutation frequency was lower than in the control, and an U-shaped dose response relationship was suggested. In a mutant strain defective in DNA repair function, dose response was linear. Here, we introduced baculovirus p35 gene into wild-type flies to suppress apoptosis function in the posterior region of their wings. In these flies, mutation frequency increased in the posterior region of the wings. Especially, terminal deletion of the third chromosome and non-disjunction increased drastically, whereas somatic recombination was not influenced by the suppression of apoptosis. The dose-response curve was U-shaped when apoptosis was suppressed, suggesting that the contribution of apoptosis function to the formation of U-shaped dose-response relationship is not as large as DNA repair function.
