@article{oai:repo.qst.go.jp:00045279,
 author = {Yasuda, Takako and Yoshimoto, Masami and Maeda, Keiko and Matsumoto, Atsuko and Maruyama, Kouichi and Ishikawa, Yuuji and 保田 隆子 and 前田 圭子 and 松本 厚子 and 丸山 耕一 and 石川 裕二},
 issue = {5},
 journal = {Journal of Radiation Research},
 month = {Sep},
 note = {We describe a novel method of rapid and quantitative evaluation of the degree of radiation-induced apoptosis in the developing brain of medaka (Oryzias latipes). Embryos at stage 28 were irradiated with 1, 2, 3.5, and 5 Gy of X-rays. Twenty to twenty-four hours after the irradiation, living embryos were stained with a vital dye, acridine orange (AO), for 1-2 h, and whole-mount brains were examined under an epifluorescence microscope. The numbers of AO-stained rosette-shaped nuclear clusters and AO-stained single nuclei increased in a dose-dependent manner in the optic tectum. Electron microscopy revealed that the AO-stained rosette-shaped nuclear clusters were the nuclei of aggregated apoptotic cells. We used the number of AO-stained rosette-shaped nuclear clusters/tectum as an index of the degree of radiation-induced brain cell death. The results showed that the number of rosette-shaped nuclear clusters/optic tectum in irradiated embryos exposed to higher than 2 Gy was highly significantly different from that in nonirradiated control embryos, whereas no difference was detected at 1 Gy. Thus, the threshold dose for brain cell death in medaka embryos is about 1 Gy and this dose is probably comparable to those for rodents and humans. The results show that medaka embryos are useful for quantitative evaluation of developmental neurocytotoxic effects of radiation.},
 pages = {533--540},
 title = {Rapid and simple method for quantitative evaluation of neurocyototoxic effects of radiation on developing medaka brain},
 volume = {49},
 year = {2008}
}