Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong.
J Radiat Res. 2012;53(3):475-81. Epub 2012 Apr 13.
The microbeam irradiation system (Single-Particle Irradiation System to Cell, acronym as SPICE) at the National Institute of Radiological Sciences (NIRS), Japan, was employed to irradiate dechorionated zebrafish embryos at the 2-cell stage at 0.75 h post fertilization (hpf) by microbeam protons. Either one or both of the cells of the embryos were irradiated with 10, 20, 40, 50, 80, 100, 160, 200, 300 and 2000 protons each with an energy of 3.37 MeV. The embryos were then returned back to the incubator until 24 hpf for analyses. The levels of apoptosis in zebrafish embryos at 25 hpf were quantified through terminal dUTP transferase-mediated nick end-labeling (TUNEL) assay, with the apoptotic signals captured by a confocal microscope. The results revealed a triphasic dose-response for zebrafish embryos with both cells irradiated at the 2-cell stage, namely, (1) increase in apoptotic signals for < 200 protons (< 30 mGy), (2) hormesis to reduce the apoptotic signals below the spontaneous number for 200-400 protons (at doses of 30-60 mGy), and (3) increase in apoptotic signals again for > 600 protons (at doses > 90 mGy). The dose response for zebrafish embryos with only one cell irradiated at the 2-cell stage was also likely a triphasic one, but the apoptotic signals in the first zone (< 200 protons or < 30 mGy) did not have significant differences from those of the background. At the same time, the experimental data were in line with induction of radiation-induced bystander effect as well as rescue effect in the zebrafish embryos, particular in those embryos with unirradiated cells.
日本放射线医学综合研究所的微束照射系统（单细胞照射系统，简称 SPICE）用于在受精后 0.75 小时（hpf）对脱壳斑马鱼胚胎进行 2 细胞期的微束质子照射。胚胎的一个或两个细胞分别用 10、20、40、50、80、100、160、200、300 和 2000 个质子照射，每个质子的能量为 3.37 MeV。然后将胚胎放回孵化器中，直到 24 hpf 进行分析。通过末端脱氧核苷酸转移酶介导的缺口末端标记（TUNEL）测定法对 25 hpf 时斑马鱼胚胎中的细胞凋亡水平进行定量分析，通过共聚焦显微镜捕获凋亡信号。结果表明，在 2 细胞期对两个细胞进行照射的斑马鱼胚胎存在三阶段剂量反应，即：（1）<200 个质子（<30 mGy）时凋亡信号增加；（2）200-400 个质子（30-60 mGy 剂量）时产生减少凋亡信号的激素效应；（3）>600 个质子（>90 mGy 剂量）时再次增加凋亡信号。在 2 细胞期仅一个细胞受到照射的斑马鱼胚胎的剂量反应也可能是三阶段的，但第一个区域（<200 个质子或<30 mGy）的凋亡信号与背景信号没有显著差异。同时，实验数据与辐射诱导的旁观者效应以及斑马鱼胚胎中的拯救效应一致，特别是在未受照射细胞的胚胎中。
