Lukins Philip B, Rehman Shakil, Stevens Gregory B, George Doaa
School of Physics, University of Sydney, NSW 2006, Australia.
Luminescence. 2005 May-Jun;20(3):143-51. doi: 10.1002/bio.819.
Fluorescence, absorption and vibrational spectroscopic techniques were used to study spinach at the photosystem II (PS II), chloroplast and cellular levels and to determine the effects and mechanisms of ultraviolet-B (UV-B) photoinhibition of these structures. Two-photon fluorescence spectroscopic imaging of intact chloroplasts shows significant spatial variations in the component fluorescence spectra in the range 640-740 nm, indicating that the type and distribution of chlorophylls vary markedly with position in the chloroplast. The chlorophyll distributions and excitonic behaviour in chloroplasts and whole plant tissue were studied using picosecond time-gated fluorescence imaging, which also showed UV-induced kinetic changes that clearly indicate that UV-B induces both structural and excitonic uncoupling of chlorophylls within the light-harvesting complexes. Transient absorption measurements and low-frequency infrared and Raman spectroscopy show that the predominant sites of UV-B damage in PS II are at the oxygen-evolving centre (OEC) itself, as well as at specific locations near the OEC-binding sites.
利用荧光、吸收和振动光谱技术，在光系统II（PS II）、叶绿体和细胞水平上对菠菜进行研究，以确定紫外线-B（UV-B）对这些结构的光抑制作用及其机制。完整叶绿体的双光子荧光光谱成像显示，在640-740nm范围内，组分荧光光谱存在显著的空间变化，这表明叶绿素的类型和分布随叶绿体中的位置而显著变化。利用皮秒时间选通荧光成像技术研究了叶绿体和整个植物组织中的叶绿素分布和激子行为，该技术还显示了紫外线诱导的动力学变化，清楚地表明UV-B诱导了捕光复合物中叶绿素的结构和激子解偶联。瞬态吸收测量以及低频红外和拉曼光谱表明，PS II中UV-B损伤的主要部位是在放氧中心（OEC）本身，以及OEC结合位点附近的特定位置。
