A modulating role for antioxidants in desiccation tolerance
A modulating role for antioxidants in desiccation tolerance
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DOI：
10.1093/icb/45.5.734
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发表时间：
2005-11-01
影响因子：
2.6
通讯作者：
Birtic, S
中科院分区：
文献类型：
--
作者：
Kranner, I;Birtic, S
大多数生物都依赖于水的供应。然而，一些生命形式，其中包括植物和真菌，但很少有动物，可以在干燥状态下生存。在这里，我们讨论的生化机制，赋予耐干燥光合和非光合生物。我们首先考虑由水去除引起的损害，并指出自由基是不耐受组织死亡的主要原因。自由基损害新陈代谢，需要在脱水和再水化过程中分别进行保护和修复。因此，干燥耐受性和干燥状态下的长寿取决于使用抗氧化剂如谷胱甘肽、抗坏血酸盐、生育酚和自由基加工酶来消除自由基的能力。一些“经典”的抗氧化剂可能不存在于低等植物和真菌中。另一方面，地衣和种子通常含有具有抗氧化特性的次级酚类产品。在所有生命形式中始终发现的主要细胞内抗氧化剂是谷胱甘肽，使其在干燥中生存必不可少。我们最后讨论谷胱甘肽作为启动程序性细胞死亡的信号的作用。抗氧化系统在长期干燥过程中的失效似乎会引发程序性细胞死亡，导致生物体老化和最终死亡。反过来，这表明一个强大的抗氧化机制是脱水耐受性的潜在机制之一。
Most organisms depend on the availability of water. However, some life-forms, among them plants and fungi, but very few animals, can survive in the desiccated state. Here we discuss biochemical mechanisms that confer tolerance to desiccation in photosynthetic and non-photosynthetic organisms. We first consider damage caused by water removal and point out that free radicals are a major cause of death in intolerant tissue. Free radicals impair metabolism and necessitate protection and repair during desiccation and rehydration, respectively. As a consequence, desiccation tolerance and prolonged longevity in the desiccated state depend on the ability to scavenge free radicals, using antioxidants such as glutathione, ascorbate, tocopherols and free radical-processing enzymes. Some 'classic' antioxidants may be absent in lower plants and fungi. On the other hand, lichens and seeds often contain secondary phenolic products with antioxidant properties. The major intracellular antioxidant consistently found in all life forms is glutathione, making it essential to survive desiccation. We finally discuss the role of glutathione to act as a signal that initiates programmed cell death. The failure of the antioxidant system during long-term desiccation appears to trigger programmed cell death, causing ageing and eventual death of the organism. In turn, this suggests that a potent antioxidant machinery is one of the underlying mechanisms of desiccation tolerance.