Genetical Instability induced by Low Doses of Radations

我们已经报道了低剂量x射线的慢性辐射对人体细胞中几种生物反应的影响。例如，与对照组相比，每周以1 cGy的伽马射线重复照射的时间明显延长。虽然未辐照对照和急性辐照细胞在26代（约10代至衰老）核型和数量正常，但同一传代的慢性辐照细胞在数量上而不是结构上出现异常。我们还发现，在照射后14天，低剂量x射线照射的细胞的显色像差频率高，约为未照射细胞的50倍。这些结果最好的解释是，假设低剂量的电离辐射会引起应激反应，可能是一种表观遗传反应，这是造成遗传不稳定的主要原因。我们推测细胞膜和细胞分裂装置等非遗传物质可能是低剂量辐射的重要靶点。

We have reported that chronic radiations with low doses of X-rays affected to several biological responses in human cells. For example, repeated-irradiation with 1 cGy per week of gamma-rays was significantly prolonged over that of control. Although non-irradiated control and acute irradiated cells at passage 26 (about 10 passages to senescence) were normal karyotype and number, chronic-irradiated cells at the same passage showed numerical, rather than structural, abnormalities. We also found that chromoshone aberration frequency of a cell irradiated with low doses of X-rays is high around 50 times of the unirradiated cells at 14 days after irradiation.These results can best be interpreted by assuming that ionizing radiation at low doses induces a stress response, probably an epigenetic one, which is responsible for the majority of the genetic instability. We speculate that non genetic materials, such as cell membrene and cell division apparatus may be important target of low dose radiations.