Chankova S G, Dimova E, Dimitrova M, Bryant P E
Central Laboratory of General Ecology-BAS, Sofia, Bulgaria.
Radiat Environ Biophys. 2007 Nov;46(4):409-16. doi: 10.1007/s00411-007-0123-2. Epub 2007 Jul 17.
This study aimed to test the potential of the radiomimetic chemical zeocin to induce DNA double-strand breaks (DSB) and "adaptive response" (AR) in Chlamydomonas reinhardtii strain CW15 as a model system. The AR was measured as cell survival using a micro-colony assay, and by changes in rejoining of DSB DNA. The level of induced DSB was measured by constant field gel electrophoresis based on incorporation of cells into agarose blocks before cell lysis. This avoids the risk of accidental induction of DSB during the manipulation procedures. Our results showed that zeocin could induce DSB in C. reinhardtii strain CW15 in a linear dose-response fashion up to 100 microg ml(-1) which marked the beginning of a plateau. The level of DSB induced by 100 microg ml(-1) zeocin was similar to that induced by 250 Gy of gamma-ray irradiation. It was also found that, similar to gamma rays, zeocin could induce AR measured as DSB in C. reinhardtii CW15 and this AR involved acceleration of the rate of DSB rejoining, too. To our knowledge, this is the first demonstration that zeocin could induce AR in some low eukaryotes such as C. reinhardtii.
本研究旨在测试放射模拟化学物质博来霉素（zeocin）在莱茵衣藻（Chlamydomonas reinhardtii）CW15菌株中诱导DNA双链断裂（DSB）和“适应性反应”（AR）的潜力，将其作为一个模型系统。通过微菌落试验以细胞存活率来衡量适应性反应，并通过DSB DNA重连的变化来衡量。基于细胞在裂解前被掺入琼脂糖块，利用恒定电场凝胶电泳来测量诱导的DSB水平。这避免了在操作过程中意外诱导DSB的风险。我们的结果表明，博来霉素能以线性剂量反应方式在莱茵衣藻CW15菌株中诱导DSB，直至100微克/毫升（-1），这标志着平台期的开始。100微克/毫升（-1）博来霉素诱导的DSB水平与250戈瑞γ射线照射诱导的水平相似。还发现，与γ射线类似，博来霉素能在莱茵衣藻CW15中诱导以DSB衡量的适应性反应，并且这种适应性反应也涉及DSB重连速率的加快。据我们所知，这是首次证明博来霉素能在一些低等真核生物如莱茵衣藻中诱导适应性反应。
