Light-Induced Changes in the Fluorescence Yield of Chlorophyll a In Vivo

Abstract

The fluorescence transient of Chlorella pyrenoidosa, excited by saturating light absorbed mainly by system II, has a dip D between the peak I at 75 msec and the large peak P at 400 msec (the times depend on light intensity). This dip is observed in aerobic cells and in anaerobic cells where it is prominent. In anaerobic cells, the I-D decline is hastened almost equally by absorption of either 705 or 650 nm background light. In anaerobic cells, supplementary 700 and 710 nm light given during the transient slightly hastens and heightens P. Methyl viologen, an exogenous system I electron acceptor, eliminates P. Results suggest that system I action causes D, and that P is due to reduction of Q (fluorescence quencher) and intersystem intermediates caused by development of a block in oxidation of XH (X being the primary electron acceptor of light reaction I). Mathematical analysis suggests that if only two forms of Q participate beyond I, then system I action is required for D. If three forms participate, then the system Q --> QH --> Q' (see text) may explain D. The Malkin model (14), in its present form, does not allow D.

Light‐harvesting in Acaryochloris marina – spectroscopic characterization of a chlorophyll d‐dominated photosynthetic antenna system

“…Unbalanced excitation of PS II and PS I affects the I-D-P kinetics: predominant excitation of PS II results in the disappearance of the I-D lag phase, whereas predominant excitation of PS I results in a pronounced minimum at D [13,14]. Thus, the fluorescence induction curve is indicative that upon excitation of Chi d (at 461 nm) PS II and PS I are excited to approximately the same extent.…”

Temperature Effects on Pea Plants Probed by Simultaneous Measurements of the Kinetics of Prompt Fluorescence, Delayed Fluorescence and Modulated 820 nm Reflection

“…During the time interval from 2 to ∼200 ms, multiple charge separation occurs and the redox components of the electron transport chain become reduced (see [4] for review). The I–P phase is related to PSI activity [33], [34], [35]. For modulated reflection signals the first reliable MR measurement was at 0.3 ms.…”

Characterization of the Inhibition of Photosynthetic Electron Transport in Pea Chloroplasts by the Herbicide 4,6-Dinitro-o-cresol by Comparative Studies with 3-(3,4-Dichlorophenyl)-1,1- dimethylurea

“…Fluorescence transients were mea sured as described by Munday and Govindjee [7]. The photomultiplier signal was fed through a Tek tronix oscilloscope (Type 502) and recorded on an Esterline Angus (Model E 11015) recorder.…”