Abstract
We analyze the mechanisms of radiation tolerance found in plants 1), 2). We also developed the ion-microbeam system for irradiating single plant cells 3). This is the first system for irradiating non-adherent cells with microbeam. In this meeting, we introduce our system and biological effects of ion-microbeam irradiation in single tobacco cells.
Single tobacco cells were plated in an agarose medium onto an irradiation vessel, in which CR-39 nuclear track detector was set on the bottom. The cells were irradiated with 17.5 MeV/amu Ne and 18.3 MeV/amu C ion microbeam that were accelerated by cyclotron at JAERI-Takasaki and collimated through a 20-μmΦ aperture. After irradiation, ion tracks were detected by alkaline etching of CR-39 and hit rate of ions (No. of ions that actually hit an aimed cell / No. of ions counted by a scintillator-photomultiplier assembly) was determined. Colony formation rate of the cells was also measured after a month.
Hit rates of Ne and C ions were 84±3 and 73±6%, respectively. Colony formation rate of tobacco BY-2 cells was reduced to half, as cells were hit by 25 and 100 particles of Ne (LET = 377 keV/μm) and C (116 keV/μm) ions, respectively. We will plan to obtain survival curves of single tobacco cells using this ion microbeam system and compare the results with those obtained by the broad-field irradiation.
References:
1) Yokota et al. (2003) Int. J. Radiat. Biol. 79
2) Yokota et al. (2005) Radiat. Res. 163
3) Yokota et al. (2003) Biol. Sci. Space 18
