Project description:Linear energy transfer (LET) is an important factor affecting several aspects of the irradiation effect, e.g. cell survival and mutation frequency, making the heavy-ion beam an effective mutagen. To study the mechanisms behind LET-dependent effects, expression profiling was performed after heavy-ion beam irradiation of imbibed rice seeds. Array-based experiments at three time points (0.5, 1, 2 h after the irradiation) revealed that the number of up- or down-regulated genes was highest 2 h after irradiation. Array-based experiments with four different LETs at 2 h after irradiation identified LET-independent regulated genes that were up/down-regulated regardless of the value of LET; LET-dependently regulated genes, whose expression level increased with the rise of LET value, were also identified.
Project description:Linear energy transfer (LET) is an important factor affecting several aspects of the irradiation effect, e.g. cell survival and mutation frequency, making the heavy-ion beam an effective mutagen. To study the mechanisms behind LET-dependent effects, expression profiling was performed after heavy-ion beam irradiation of imbibed rice seeds. Array-based experiments at three time points (0.5, 1, 2 h after the irradiation) revealed that the number of up- or down-regulated genes was highest 2 h after irradiation. Array-based experiments with four different LETs at 2 h after irradiation identified LET-independent regulated genes that were up/down-regulated regardless of the value of LET; LET-dependently regulated genes, whose expression level increased with the rise of LET value, were also identified.
Project description:Linear energy transfer (LET) is an important factor affecting several aspects of the irradiation effect, e.g. cell survival and mutation frequency, making the heavy-ion beam an effective mutagen. To study the mechanisms behind LET-dependent effects, expression profiling was performed after heavy-ion beam irradiation of imbibed rice seeds. Array-based experiments at three time points (0.5, 1, 2 h after the irradiation) revealed that the number of up- or down-regulated genes was highest 2 h after irradiation. Array-based experiments with four different LETs at 2 h after irradiation identified LET-independent regulated genes that were up/down-regulated regardless of the value of LET; LET-dependently regulated genes, whose expression level increased with the rise of LET value, were also identified. Oryza sativa L. 'Nipponbare' seeds were imbibed for 3 days. The seeds were irradiated with 22.5 or 50 keV/μm C-ion at a dose of 15 Gy. Gene expressions of irradiated and unirradiated embryos were measured at 0.5, 1, and 2 hours after irradiation. Three independent experiments were performed at each time and LET.
Project description:Linear energy transfer (LET) is an important factor affecting several aspects of the irradiation effect, e.g. cell survival and mutation frequency, making the heavy-ion beam an effective mutagen. To study the mechanisms behind LET-dependent effects, expression profiling was performed after heavy-ion beam irradiation of imbibed rice seeds. Array-based experiments at three time points (0.5, 1, 2 h after the irradiation) revealed that the number of up- or down-regulated genes was highest 2 h after irradiation. Array-based experiments with four different LETs at 2 h after irradiation identified LET-independent regulated genes that were up/down-regulated regardless of the value of LET; LET-dependently regulated genes, whose expression level increased with the rise of LET value, were also identified. Oryza sativa L. 'Nipponbare' seeds were imbibed for 3 days. The seeds were irradiated with 22.5 or 50 keV/μm C-ion or 63 or 80 keV/μm Ne-ion at a dose of 15 Gy. Gene expressions of irradiated and unirradiated embryos were measured at 2 hours after irradiation. Three independent experiments were performed at each time and LET.
Project description:Female B6C3F1 mice were received 4 doses (1 dose per week) of whole-body 1.6 Gy carbon ions starting at age 4–5 weeks. Each irradiation was conducted with a 290 MeV/u carbon-ion beam (average LET 60 keV/µm) at the Heavy Ion Medical Accelerator in Chiba, Japan. The mice were monitored throughout their lifespan. Thymic lymphomas obtained from these mice were analyzed to identify characteristic genomic alterations induced by carbon-ion irradiation. The results revealed that thymic lymphomas arising after four-fractionated high-LET carbon-ion irradiation frequently exhibited loss of heterozygosity in the region containing the thymic lymphoma–associated gene Ikzf1 on chromosome 11, due to extensive genomic deletions.