Abstract
The microbeam irradiation study of a cultured cell contributed to the development of the radiation-biology research, e.g. bystander effect 1). An advantage of a microbeam is localized irradiation, and the microbeam has been applied to the comparative study of radiation effects between a nucleus, cytoplasm and membrane. On the other hand, we have used Caenorhabditis elegans as a model multicellular organism which contained about 1000 cells, and push forward a heavy-ion microbeam irradiation individual-study. As for about 1.2 mm in a range of carbon ions in water, all cells and tissues of C. elegans are microbeam irradiation objects. At present, the target area is several dozens μm in a diameter, depending on the limits of beam-size of collimated microbeams and observation ability of the inverted microscope by the interference with the end part of the microbeam line. Using this system, Sugimoto et al. showed DNA-damage-induced cell cycle arrest and apoptosis in locally irradiated areas of C. elegans 2). We focus the nervous system of C. elegans (occupied about 30% of all cells) and study the effects of localized irradiation on learning behavior (food-NaCl associative learning 3)). However, the anesthetic method for fixation of <I)C. elegans 2) is not usable because the whole body irradiation of 60Co gamma rays affected only transition stage of the conditioning for food-NaCl associative learning. Thus, now we are constructing the heavy-ion microbeam irradiation system for living target C. elegans.
References: 1) Shao et al., FASEB J 17, 1422-7 (2003), 2) Sugimoto et al., Int J Radiat Biol 82, 31-8 (2006), 3) Saeki et al., J Exp Biol 204, 1757-64 (2001).
