Department of Botany, Berhampur University, Berhampur, India.
Mutat Res. 2013 Mar 18;751(2):130-8. doi: 10.1016/j.mrgentox.2012.12.008. Epub 2013 Jan 8.
Calcium is an important second messenger in signal transduction pathways. The role of Ca(2+) signalling in Al-induced DNA damage, cell death, and adaptive response to genotoxic stress caused by ethyl methanesulfonate (EMS) or methylmercuric chloride (MMCl) in the root cells of Allium cepa was investigated in the current study. Root cells in planta were treated with Al(3+) (800μM of AlCl(3)) for 3h without or with 2h pre-treatment with the Ca(2+) chelator (EGTA) or Ca(2+) channel blockers (lanthanum chloride, verapamil) or CaM/CDPK antagonist (W7). In addition, root cells in planta were conditioned by treatment with Al(3+) (5 or 10μM of AlCl(3)) for 2h followed by the genotoxic challenge with MMCl (1.25μM) or EMS (2.5 or 5mM) for 3h without or with the pre-treatment of the chosen Ca(2+) chelator/channel blockers/antagonist. Following the treatments, cell death and DNA damage were investigated in the root cells by comet assay. Furthermore, genotoxicity in the root meristems was determined after 18-30h of recovery. These results revealed that Al(3+) (800μM) significantly induced DNA damage and cell death in the root cells of A. cepa. On the other hand, conditioning of the root cells with Al(3+) at low concentrations (5 or 10μM) offered adaptive response leading to the protection against genotoxic stress induced by MMCl and EMS. Pre-treatment of root cells with the Ca(2+) chelator/channel blockers/antagonist not only alleviated Al(3+)-induced DNA damage and cell death induced but also blocked the Al(3+)-mediated adaptive response to genotoxic stress induced by MMCl and EMS. For the first time, the results of the present study highlighted the role of Ca(2+) signalling underlying the biphasic mode of action of Al(3+) that induced DNA damage and cell death at high doses and offered adaptation to genotoxic response in plants at low doses.
钙是信号转导途径中的一种重要的第二信使。本研究旨在探讨钙离子信号在铝诱导的 DNA 损伤、细胞死亡以及植物体内洋葱根细胞对乙基甲磺酸（EMS）或甲基汞（MMCl）等遗传毒性应激的适应性反应中的作用。在没有或用钙离子螯合剂（EGTA）或钙离子通道阻滞剂（氯化镧、维拉帕米）或钙调蛋白/钙调蛋白依赖性蛋白激酶拮抗剂（W7）预处理 2 小时的情况下，用 Al(3+)（800μM 的 AlCl(3)）处理植物体内的根细胞 3 小时。此外，用 Al(3+)（5 或 10μM 的 AlCl(3)）预处理 2 小时，然后用 MMCl（1.25μM）或 EMS（2.5 或 5mM）进行 3 小时的遗传毒性挑战，在没有或用选定的钙离子螯合剂/通道阻滞剂/拮抗剂预处理的情况下，对植物体内的根细胞进行处理。处理后，通过彗星试验研究根细胞中的细胞死亡和 DNA 损伤。此外，在 18-30 小时的恢复后，确定根分生组织中的遗传毒性。结果表明，Al(3+)（800μM）显著诱导洋葱根细胞的 DNA 损伤和细胞死亡。另一方面，用低浓度（5 或 10μM）的 Al(3+)对根细胞进行预处理，可提供适应性反应，从而防止由 MMCl 和 EMS 引起的遗传毒性应激。根细胞用钙离子螯合剂/通道阻滞剂/拮抗剂预处理，不仅减轻了 Al(3+)诱导的 DNA 损伤和细胞死亡，而且阻断了 Al(3+)介导的对由 MMCl 和 EMS 引起的遗传毒性应激的适应性反应。本研究首次强调了钙离子信号在铝的双相作用模式中的作用，即在高剂量下诱导 DNA 损伤和细胞死亡，在低剂量下为植物提供对遗传毒性反应的适应。
