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Diurnal variations in the kinetics of delayed luminescence from Scenedesmus obtusiusculus after exposure to various light and CO 2 regimes
Author(s) -
Mellvig Staffan
Publication year - 1987
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1987.tb02837.x
Subject(s) - luminescence , scenedesmus , kinetics , chemistry , plastoquinone , biophysics , photochemistry , biochemistry , biology , materials science , algae , botany , physics , chloroplast , optoelectronics , thylakoid , quantum mechanics , gene
Delayed luminescence was measured from samples of a synchronously growing cell culture of the unicellular green alga, Scenedesmus obtusiusculus Chod., every second hour during the 24 h cell cycle under a 15/9 h lighi/dark regime. Both high (air + 2.5% CO 2 ) and low (0.03% CO 2 ) CO 2 conditions were used. Under high CO 2 conditions, while light excitation induces formation of a late (maximum reached after 10–60 s) transient peak in delayed luminescence in cells sampled after 10–16 h in the cell cycle. During most of the cell cycle low CO 2 conditions stimulate a late transient peak formation. Excitation with 700 nm light, but not with 680 nm light, induces a late transient peak in delayed luminescence under high CO 2 conditions. The transient peak is more or less pronounced depending on the cell stage. The variations might be due to a changing capacity for light‐induced state I/stale II transitions during the cell cycle. It is assumed that the formation of a late transient peak in delayed luminescence is due to ATP hydrolyzation and is thus favoured by a high ATP/NADPH ratio. Hydrolyzation of ATP affects the transthylakoidal ΔpH, which regulates the reverse electron flow to the plastoquinone‐pool and Q A /Q B , thus affecting the decay kinetics of the delayed luminescence.