Changes in intensity and spectral distribution of fluorescence. Effect of light treatment on normal and DCMU-poisoned Anacystis nidulans.
The intensity of the "steady-state" fluorescence of "aerobic" Anacystis nidulans is variable under prolonged illumination with orange (590 mmu) or blue (440 mmu) light for both normally photosynthesizing and DCMU-poisoned cells. In general, orange light illumination causes an increase of the fluorescence intensity followed by a decrease, while blue light causes an increase until a steady level is reached. Poisoned Anacystis cells show four to eight times larger changes in fluorescence intensity than the normal cells; the detailed time course of fluorescence changes is also different in poisoned and normal cells. When algae are cooled to -196 degrees C in light, the light-induced changes in the "steady-state" fluorescence disappear in both types of cells. Difference fluorescence spectra, constructed by subtracting the fluorescence spectra taken after 5-15 min of illumination from those after 60-90 min of illumination, show a doublet structure of the difference band with a major peak coinciding with the Anacystis emission maximum (685 mmu) and a minor peak located at about 693 mmu.
D002734:Chlorophyll; D056890:Eukaryota / Q000187:drug effects*; D005453:Fluorescence; D007700:Kinetics; D008027:Light; D010788:Photosynthesis; D013057:Spectrum Analysis; D013696:Temperature; D014508:Urea / Q000494:pharmacology*
D002734:Chlorophyll; D014508:Urea