Oxidative Signals in Tobacco Increase Cytosolic Calcium.
Oxidative Signals in Tobacco Increase Cytosolic Calcium.
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DOI：
10.1105/tpc.6.9.1301
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发表时间：
1994-09
期刊：
影响因子：
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通讯作者：
A. Price;A. Taylor;Scott J. Ripley;A. Griffiths;A. Trewavas;M. Knight
中科院分区：
文献类型：
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作者：
A. Price;A. Taylor;Scott J. Ripley;A. Griffiths;A. Trewavas;M. Knight
将转Aequorin基因的烟草(Nictiana Plumaginifolia)幼苗在h-Coelentazine中孵育，重组钙敏感发光蛋白Aequorin。用过氧化氢处理这些幼苗，导致钙依赖的发光瞬间爆发，持续几分钟。尽管过氧化氢刺激是持续的，但胞浆游离钙浓度([Ca~(2+)]Cyt)的变化是短暂的，提示存在不应期。当幼苗用过氧化氢预处理时，第二次处理时[Ca~(2+)]Cyt没有增加，这证实了反应的顽固性。只有当两个治疗间隔4至8小时时，才能完全恢复反应。然而，过氧化氢处理并没有抑制冷休克或触摸诱导的细胞内钙离子的动员，这表明这三种信号动员了不同的细胞内钙池。为了研究细胞质的氧化还原状态是否调节细胞内[Ca~(2+)]-Cyt，我们用丁硫氨酸亚磺胺(以改变细胞内谷胱甘肽水平)和抗坏血酸过氧化物酶抑制剂对幼苗进行预处理。这些抑制剂改变了过氧化氢诱导的细胞内[Ca~(2+)]Cyt的瞬变，这与它们对细胞促氧化/抗氧化比率的影响是一致的。过氧化氢处理引起细胞内[Ca~(2+)]-CyT升高，也导致超氧化物歧化酶活性降低。这种减少可以用钙通道阻滞剂镧来逆转。这表明钙在植物对氧化胁迫的反应中有一定的作用。
Tobacco (Nicotiana plumbaginifolia) seedlings genetically transformed to express apoaequorin were incubated in h-coelenterazine to reconstitute the calcium-sensitive luminescent protein aequorin. Treatment of these seedlings with hydrogen peroxide resulted in a transient burst of calcium-dependent luminescence lasting several minutes. Even though the hydrogen peroxide stimulus was persistent, the change in cytosolic free calcium concentration ([Ca2+]cyt) was transient, suggesting the presence of a refractory period. When seedlings were pretreated with hydrogen peroxide, there was no increase in [Ca2+]cyt upon a second application, which confirmed the refractory character of the response. Only when the two treatments were separated by 4 to 8 hr was full responsiveness recovered. However, treatment with hydrogen peroxide did not inhibit mobilization of [Ca2+]cyt induced by either cold shock or touching, suggesting that these three signals mobilize different pools of intracellular calcium. To examine whether [Ca2+]cyt is regulated by the redox state of the cytoplasm, we pretreated seedlings with buthionine sulfoximine (to modify cellular glutathione levels) and inhibitors of ascorbate peroxidase. These inhibitors modify the hydrogen peroxide-induced transients in [Ca2+]cyt, which is consistent with their effects on the cellular prooxidant/antioxidant ratio. Treatment with hydrogen peroxide that elicited [Ca2+]cyt increases also brought about a reduction in superoxide dismutase enzyme activity. This reduction could be reversed by treatment with the calcium channel blocker lanthanum. This indicates that there is a role for calcium in plant responses to oxidative stress.