Kana Radek, Prásil Ondrej, Komárek Ondrej, Papageorgiou George C
Laboratory of Photosynthesis, Institute of Microbiology, Academy of Sciences Czech Republic, Trebon, Czech Republic.
Biochim Biophys Acta. 2009 Oct;1787(10):1170-8. doi: 10.1016/j.bbabio.2009.04.013. Epub 2009 May 3.
We present here three-dimensional time-wavelength-intensity displays of changes in variable fluorescence, during the O(JI)PSMT transient, observed in cyanobacterium at room temperature. We were able to measure contributions of individual chromophores to fluorescence spectra at various times of fluorescence induction (FI). The method was applied to a freshwater cyanobacterium, Synechococcus sp. (PCC 7942). Analysis of our experimental results provides the following new conclusions: (i) the main chlorophyll (Chl) a emission band at approximately 685 nm that originates in Photosystem (PS) II exhibits typical fast (OPS) and slow (SMT) FI kinetics with both orange (622 nm) and blue (464 nm) excitation. (ii) Similar kinetics are exhibited for its far-red emission satellite band centered at approximately 745 nm, where the PS II contribution predominates. (iii) A significant OPS-SMT-type kinetics of C-phycocyanin emission at approximately 650 nm are observed with the blue light excitation, but not with orange light excitation where the signal rose only slightly to a maximum. The induction of F650 was not caused by an admixture of the F685 fluorescence and thus our data show light-inducible and dark-reversible changes of phycobilin fluorescence in vivo. We discuss possible interpretations of this new observation.
我们在此展示了在室温下对蓝细菌进行观察时，于O(JI)PSMT瞬态期间可变荧光变化的三维时间-波长-强度显示。我们能够测量各个发色团在荧光诱导（FI）不同时间对荧光光谱的贡献。该方法应用于一种淡水蓝细菌，聚球藻属（Synechococcus sp.，PCC 7942）。对我们实验结果的分析得出以下新结论：（i）起源于光系统（PS）II的约685 nm处的主要叶绿素（Chl）a发射带，在橙色（622 nm）和蓝色（464 nm）激发下均呈现典型的快速（OPS）和慢速（SMT）FI动力学。（ii）以约745 nm为中心的其远红发射卫星带也呈现类似动力学，其中PS II的贡献占主导。（iii）在蓝光激发下观察到约650 nm处藻蓝蛋白发射有显著的OPS-SMT型动力学，但在橙光激发下未观察到，橙光激发时信号仅略有上升至最大值。F650的诱导并非由F685荧光的混合引起，因此我们的数据显示了体内藻胆蛋白荧光的光诱导和暗可逆变化。我们讨论了这一新观察结果的可能解释。
