Discipline of Marine Biotechnology and Ecology, Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, Gijubhai Badheka Marg, Bhavnagar 364021, India.
Plant Physiol Biochem. 2012 Feb;51:129-38. doi: 10.1016/j.plaphy.2011.10.016. Epub 2011 Nov 10.
The protective role of exogenously supplied selenium (Se) and polyamines (PAs) such as putrescine (Put) and spermine (Spm) in detoxifying the cadmium (Cd) induced toxicity was studied in the marine red alga Gracilaria dura in laboratory conditions. The Cd exposure (0.4 mM) impede the growth of alga while triggering the reactive oxygen species (ROS viz. O(2)(•-) and H(2)O(2)) generation, inhibition of antioxidant system, and enhancing the lipoxygenase (LOX) activity, malondialdehyde (MDA) level and demethylation of DNA. Additions of Se (50 μM) and/or Spm (1 mM) to the culture medium in contrast to Put, efficiently ameliorated the Cd toxicity by decreasing the accumulation of ROS and MDA contents, while restoring or enhancing the level of enzymatic and nonenzymatic antioxidants and their redox ratio, phycobiliproteins and phytochelatins, over the controls. The isoforms of antioxidant enzymes namely superoxide dismutase (Mn-SOD, ~150 kDa; Fe-SOD ~120 kDa), glutathione peroxidase (GSH-Px, ~120 and 140 kDa), glutathione reductase (GR, ~110 kDa) regulated differentially to Se and/or Spm supplementation. Furthermore, it has also resulted in enhanced levels of endogenous PAs (specially free and bound insoluble Put and Spm) and n-6 PUFAs (C20-3, n-6 and C20-4, n-6). This is for the first time wherein Se and Spm were found to regulate the stabilization of DNA methylation by reducing the events of cytosine demethylation in a mechanism to alleviate the Cd stress in marine alga. The present findings reveal that both Se and Spm play a crucial role in controlling the Cd induced oxidative stress in G. dura.
在实验室条件下，研究了外源硒 (Se) 和多胺 (PAs)（如腐胺 (Put) 和精胺 (Spm)）在解毒镉 (Cd) 诱导的毒性方面的保护作用，以海洋红藻石花菜为研究对象。暴露于 Cd（0.4 mM）会抑制藻类生长，同时引发活性氧 (ROS，即 O(2)(•-) 和 H(2)O(2)) 的产生、抗氧化系统的抑制以及增强脂氧合酶 (LOX) 活性、丙二醛 (MDA) 水平和 DNA 的去甲基化。与 Put 相比，将 Se（50 μM）和/或 Spm（1 mM）添加到培养基中，可通过减少 ROS 和 MDA 含量的积累，有效地改善 Cd 毒性，同时恢复或增强酶和非酶抗氧化剂及其氧化还原比、藻胆蛋白和植物螯合肽的水平。抗氧化酶的同工型，即超氧化物歧化酶 (Mn-SOD，150 kDa；Fe-SOD120 kDa)、谷胱甘肽过氧化物酶 (GSH-Px，120 和 140 kDa)、谷胱甘肽还原酶 (GR，110 kDa)，对 Se 和/或 Spm 的补充有不同的调节作用。此外，它还导致内源性 PAs（特别是游离和结合的不溶性 Put 和 Spm）和 n-6 PUFAs（C20-3，n-6 和 C20-4，n-6）水平的提高。这是首次发现 Se 和 Spm 通过减少胞嘧啶去甲基化事件来调节 DNA 甲基化的稳定，从而减轻海洋藻类中的 Cd 胁迫。本研究结果表明，Se 和 Spm 在控制 Cd 诱导的 G. dura 氧化应激中发挥着至关重要的作用。
