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首页> 外文期刊>Photosynthesis Research: An International Journal >A portable, non-focusing optics spectrophotometer (NoFOSpec) for measurements of steady-state absorbance changes in intact plants
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A portable, non-focusing optics spectrophotometer (NoFOSpec) for measurements of steady-state absorbance changes in intact plants

机译：便携式非聚焦光学分光光度计（NoFOSpec），用于测量完整植物中的稳态吸收率变化

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摘要

Kinetically-resolved absorbance measurements during extended, or steady-state illumination are typically hindered by large, light-induced changes in the light-scattering properties of the material. In this work, a new type of portable spectrophotometer, the Non-Focusing Optical Spectrophotometer (NoFOSpec), is introduced, which reduces interference from light-scattering changes and is in a form suitable for fieldwork. The instrument employs a non-focusing optical component, called a compound parabolic concentrator (CPC), to simultaneously concentrate and homogeneously diffuse measuring and actinic light (from light-emitting diode sources) onto the leaf sample. Light passing through the sample is then collected and processed using a subsequent series of CPCs leading to a photodiode detector. The instrument is designed to be compact, lightweight and rugged for field work. The pulsed measuring beam allows for high sensitivity (typically < 100 ppm noise) and time resolution (&SIM; 10 μs) measurements in the visible and near infrared spectral regions. These attributes allow high-resolution measurements of signals associated with energization of the thylakoid membrane (the electrochromic shifting of carotenoid pigments), as well as electron transfer, e.g., the 820-nm changes associated with electron transfer through Photosystem I (PS I). In addition, the instrument can be used as a kinetic fluorimeter, e.g., to measure saturation-pulse fluorescence changes indicative of Photosystem II (PS II) quantum efficiency. The instrument is demonstrated by estimating electron and proton fluxes through the photosynthetic apparatus in an intact tobacco leaf, using respectively the saturation-pulse fluorescence changes and dark-interval relaxation kinetics (DIRK) of the electrochromic shift. A linear relationship was found, confirming our earlier results with the laboratory-based diffused-optics flash spectrophotometer, indicating a constant H+/e(-) stoichiometry for linear electron transfer, and suggesting that cyclic electron flow around PS I is either negligible or proportional to linear electron flow. This type of measurement should be useful under field conditions for estimating the extent of PS I cyclic electron transfer, which is proposed to operate under stressed conditions.
机译：在长时间或稳态照明期间，动力学分辨的吸光度测量通常会受到材料的光散射特性中较大的光诱导变化的阻碍。在这项工作中，引入了一种新型的便携式分光光度计，即非聚焦光学分光光度计（NoFOSpec），它可以减少来自光散射变化的干扰，并且其形式适合于现场工作。该仪器采用称为复合抛物线聚光器（CPC）的非聚焦光学组件，同时将测量和光化光（来自发光二极管源）的光聚集并均匀地扩散到叶片样品上。然后收集通过样品的光，并使用随后的一系列CPC引导至光电二极管检测器进行处理。该仪器设计紧凑，轻巧且坚固耐用，适合野外工作。脉冲测量光束允许在可见光和近红外光谱区域进行高灵敏度（通常<100 ppm噪声）和时间分辨率（＆SIM; 10μs）测量。这些属性允许高分辨率测量与类囊体膜通电相关的信号（类胡萝卜素色素的电致变色）以及电子转移，例如与通过光系统I（PS I）的电子转移相关的820 nm变化。另外，该仪器可用作动能荧光计，例如用于测量指示光电系统II（PS II）量子效率的饱和脉冲荧光变化。通过分别使用电致变色位移的饱和脉冲荧光变化和暗间隔弛豫动力学（DIRK）估算完整烟草叶片中通过光合作用设备的电子和质子通量来证明该仪器。发现了线性关系，证实了我们基于实验室的漫射光散射分光光度计的早期结果，表明线性电子转移的H + / e（-）化学计量常数恒定，表明PS I周围的循环电子流可以忽略不计或成比例线性电子流。这种类型的测量在野外条件下对估计PS I循环电子转移的程度应该是有用的，而PS I循环电子转移的建议是在压力条件下进行。

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