Sugimoto Tomoko, Dazai Kumiko, Sakashita Tetsuya, Funayama Tomoo, Wada Seiichi, Hamada Nobuyuki, Kakizaki Takehiko, Kobayashi Yasuhiko, Higashitani Atsushi
Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
Int J Radiat Biol. 2006 Jan;82(1):31-8. doi: 10.1080/09553000600577821.
To investigate positional effects of radiation with an energetic heavy-ion microbeam on germline cells using an experimental model metazoan Caenorhabditis elegans.
The germline cells were irradiated with raster-scanned broad beam or collimated microbeam of 220 MeV 12C5+ particles delivered from the azimuthally varying field (AVF) cyclotron, and subsequently observed for cell cycle arrest and apoptosis.
Whole-body irradiation with the broad beam at the L4 larval stage arrested germ cell proliferation. When the tip region of the gonad arm was irradiated locally with the microbeam at the L4 stage, the same arrest was observed. When the microbeams were used to irradiate the pachytene region of the gonad arm, at a young gravid stage, radiation-induced apoptosis occurred in the gonad. In contrast, arrest and apoptosis were not induced in the non-irradiated neighboring region or the opposite gonad. Similar results were confirmed in the c-abl-1 (mammalian ortholog of cellular counterpart of Abelson murine leukemia virus) mutant that is hypersensitive to radiation-induced apoptosis.
These results indicate that the microbeam irradiation is useful in characterizing tissue-specific, local biological response to radiation in organisms. DNA damage-induced cell cycle arrest and apoptosis were observed in locally irradiated regions, but there was little, if any, 'bystander effect' in the nematode.
利用后生动物模式生物秀丽隐杆线虫研究高能重离子微束辐射对生殖细胞的定位效应。
用从方位变化场（AVF）回旋加速器输送的220 MeV 12C5+粒子的光栅扫描宽束或准直微束照射生殖细胞，随后观察细胞周期阻滞和凋亡情况。
在L4幼虫阶段用宽束进行全身照射会使生殖细胞增殖停滞。当在L4阶段用微束局部照射性腺臂的尖端区域时，观察到了相同的停滞现象。当用微束照射年轻妊娠阶段性腺臂的粗线期区域时，性腺中发生了辐射诱导的凋亡。相比之下，未照射的相邻区域或对侧性腺未诱导出停滞和凋亡。在对辐射诱导的凋亡高度敏感的c-abl-1（阿贝尔逊鼠白血病病毒细胞对应物的哺乳动物直系同源物）突变体中也证实了类似结果。
这些结果表明，微束辐射有助于表征生物体中组织特异性的局部辐射生物学反应。在局部照射区域观察到了DNA损伤诱导的细胞周期阻滞和凋亡，但线虫中几乎没有“旁观者效应”。
