3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) Inhibition of System II and Light-Induced Regulatory Changes in Energy Transfer Efficiency

Oxygen pulses produced in Chlorella by a xenon flash of 15 μsec half-width were measured by means of a rapid oxygen polarograph. Under appropriate conditions the height of the pulse caused by a saturating flash was a measure of the number of active reaction centers in system II. In pigment state II,...

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Bibliographic Details
Published in:Biophysical journal 1972-07, Vol.12 (7), p.858-863
Main Author: Duysens, L.N. M.
Format: Article
Language:English
Subjects:
Chlorella
Chlorella - metabolism
Chlorophyta - metabolism
Depression, Chemical
Diuron - pharmacology
Energy Transfer - radiation effects
Fluorescence
Herbicides - pharmacology
Light
Oxygen - metabolism
Photochemistry
Photosynthesis - drug effects
Polarography
Radiation Effects
Urea - pharmacology
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Summary:Oxygen pulses produced in Chlorella by a xenon flash of 15 μsec half-width were measured by means of a rapid oxygen polarograph. Under appropriate conditions the height of the pulse caused by a saturating flash was a measure of the number of active reaction centers in system II. In pigment state II, caused by illumination during several minutes with light II, the number of active centers II was the same as in pigment state I. Oxygen pulses produced by about half-saturating flashes were diminished by about 7–10% in state II, showing that the fluorescence decrease in light II was at least partly caused by a decrease in energy transfer to reaction center II. After addition of 3(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), only the first flash produced oxygen which gives additional support for the hypothesis that DCMU inhibits between Q and system I.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(72)86129-0