Radiation-induced mutations in the spleen and brain of lacZ transgenic mice

Purpose: To study the dose-response and molecular nature of radiation-induc ed mutations in the spleen and brain of lacZ transgenic mice. Materials and methods: Line 60 transgenic mice containing the bacterial lac Z gene in a plasmid background were used. Mutants were selected using pheny l-beta-D-galactoside. The nature of mutants was determined by sequencing DN As of mutant lacZ genes found in control and irradiated tissues. Results: X-ray irradiation at 50 and 100 Gy showed linear dose-responses fo r mutation induction in both tissues. The slope, however, was about twice a s steep in spleen than in brain. DNA sequence analyses showed that the pred ominant type of mutation induced by radiation in both tissues were large de letions. Conclusions: Radiation induces mutations in spleen and brain at different e fficiencies but the molecular nature of the induced mutations are similar i n the two issues.