In situ detection of heavy metal substituted chlorophylls in water plants
In situ detection of heavy metal substituted chlorophylls in water plants
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DOI：
10.1023/a:1006132608181
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发表时间：
1998-11-01
影响因子：
3.7
通讯作者：
Spiller, M
中科院分区：
文献类型：
--
作者：
Küpper, H;Küpper, FC;Spiller, M
镁（叶绿素的中心原子）在体内被重金属（汞、铜、镉、镍、锌、铅）取代会导致光合作用的破坏，是重金属胁迫植物的重要损伤机制。在这项研究中，提出了多种方法来有效地原位检测这种取代（即在整个植物或叶绿体中）。虽然宏观观察表明重金属叶绿素在较高浓度下形成，但荧光显微镜能够以非常低的取代率检测到这种反应。因此，可以通过连续测量整个植物的荧光来跟踪反应过程。此外，全细胞或分离叶绿体的吸收光谱还能够对重金属叶绿素进行异位检测。这些方法提供了原位检测这些化合物形成的实用方法，避免了使用基于极性溶剂的提取方法可能出现的假象。除了原位检测的新方法之外，还观察到同一组织中的细胞对重金属胁迫的反应存在极端异质性：虽然一些细胞已经分解，但另一些细胞仍然表现出正常的荧光和光合活性。荧光动力学测量进一步提示，在高光强度下，重金属对镁的取代可能会在 PS II 反应中心发生。
The in vivo substitution of magnesium, the central atom of chlorophyll, by heavy metals (mercury, copper, cadmium, nickel, zinc, lead) leads to a breakdown in photosynthesis and is an important damage mechanism in heavy metal-stressed plants. Tn this study, a number of methods are presented for the efficient in situ detection of this subsitution (i.e. in whole plants or in chloroplasts). While macroscopic observations point to the formation of heavy metal chlorophylls at higher concentrations, fluorescence microscopy enables the detection of this reaction at very low substitution rates. Therefore, the course of the reaction can be followed by continuously measuring the fluorescence of whole plants. Furthermore absorbance spectroscopy of whole cells or isolated chloroplasts also enables the ill situ detection of heavy metal chlorophylls. These methods provide practicable approaches in detecting the formation of these compounds in situ, avoiding artefacts that might occur using extraction methods based on polar solvents. In addition to the new methods for in situ detection, an extreme heterogeneity in the reaction of cells in the Same tissue upon heavy metal stress was observed: while some cells are already disintegrating, others still show normal fluorescence and photosynthetic activity. Measurements of fluorescence kinetics gave a further hint that in high light intensity a substitution of Mg by heavy metals might take place specifically in PS II reaction centres.