title: Microbeams of heavy charged particles.
abstract: We have established a single cell irradiation system, which allows selected cells to be individually hit with defined number of heavy charged particles, using a collimated heavy-ion microbeam apparatus at JAERI-Takasaki. This system has been developed to study radiobiological processes in hit cells and bystander cells exposed to low dose and low dose-rate high-LET radiations, in ways that cannot be achieved using conventional broad-field exposures. Individual cultured cells grown in special dishes were irradiated in the atmosphere with a single or defined numbers of 18.3 MeV/amu 12C, 13.0 MeV/amu 20Ne, and 11.5 MeV/amu 40Ar ions. Targeting and irradiation of the cells were performed automatically at the on-line microscope of the microbeam apparatus according to the positional data of the target cells obtained at the off-line microscope before irradiation. The actual number of particle tracks that pass through cell nuclei was detected with prompt etching of the bottom of the cell dish made of ion track detector TNF-1 (modified CR-39), with alkaline-ethanol solution at 37 degrees C for 15-30 minutes. Using this system, separately inoculated Chinese hamster ovary cells, confluent normal human fibroblasts, and single plant cells (tobacco protoplasts) have been irradiated. These are the first studies in which single-ion direct hit effect and the bystander effect have been investigated using a high-LET heavy particle microbeam.
authors.affiliation: Research Group for Biotechnology Development, Japan Atomic Energy Research Institute (JAERI-Takasaki), Takasaki, Gunma, Japan. kobayashi@taka.jaeri.go.jp
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Tomoo
authors.initials: T
authors.lastname: Funayama
authors.forename: Seiichi
authors.initials: S
authors.lastname: Wada
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Furusawa
authors.forename: Mizuho
authors.initials: M
authors.lastname: Aoki
authors.forename: Chunlin
authors.initials: C
authors.lastname: Shao
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yokota
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakashita
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Takehiko
authors.initials: T
authors.lastname: Kakizaki
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamada
mesh_terms: D000818:Animals; D001128:Argon; D024201:Bystander Effect; D016466:CHO Cells / Q000528:radiation effects; D002244:Carbon; D002450:Cell Communication / Q000528:radiation effects; D006224:Cricetinae; D003412:Cricetulus; D005347:Fibroblasts / Q000528:radiation effects; D017629:Gap Junctions / Q000528:radiation effects; D020450:Heavy Ions; D018499:Linear Energy Transfer; D009356:Neon; D010315:Particle Accelerators; D011092:Polyethylene Glycols; D011829:Radiation Dosage; D011853:Radiobiology / Q000295:instrumentation*; D017382:Reactive Oxygen Species / Q000528:radiation effects; D014026:Nicotiana / Q000166:cytology / Q000528:radiation effects
chemical_list: D017382:Reactive Oxygen Species; C028827:CR 39; D011092:Polyethylene Glycols; D009356:Neon; D001128:Argon; D002244:Carbon