Photosynthetic Characteristics of Three Strains of Cyanobacteria Grown under Low-or High-C02 Conditions

1996 ◽  
Vol 51 (1-2) ◽  
pp. 40-46 ◽  
Author(s):  
Shigetoh Miyachi ◽  
Joachim Bürger ◽  
Kiriakos Kotzabasis ◽  
Jens Thielmann ◽  
Horst Senger
Keyword(s):  
Oxygen Evolution ◽  
Dissolved Inorganic Carbon ◽  
Electron Flow ◽  
Liquid Nitrogen Temperature ◽  
Fluorescence Induction ◽  
Anabaena Variabilis ◽  
Photosynthetic Oxygen Evolution ◽  
Induction Kinetics ◽  
Fluorescence Induction Kinetics ◽  
Photosynthetic Oxygen

Abstract Quantum requirements of photosynthetic oxygen evolution at 679 nm, fluorescence emis­sion spectra at liquid nitrogen temperature (77 K) and fluorescence induction kinetics in the presence of DCM U, were measured in the cyanobacteria Anabaena variabilis M3, Anabaena variabilis ATCC 29413 and A nacystis nidulans R2, each grown under low-or high-CO2 conditions. Low -CO2 grown cells of the cyanobacteria showed a higher quantum requirement of photosynthetic oxygen evolution and a higher ratio o F710-740 to F680-700 fluorescence and a lower variable fluorescence in the presence of DCMU than high-CO2 grown cells. These findings indicate a change in excitation energy distribution in favour of photosystem I. The result might be an enhancement in ATP formation caused by cyclic electron flow which in turn provokes dissolved inorganic carbon (DIC) accumulation in these low-CO2 grown cells.

Cyclic Electron Flow Around Photosystem II as Examined by Photosynthetic Oxygen Evolution Induced by Short Light Flashes

1997 ◽  
Vol 52 (3-4) ◽  
pp. 175-179 ◽  
Author(s):  
W. I. Gruszecki ◽  
K. Strzałka ◽  
A. Radunz ◽  
G. H. Schmid
Keyword(s):  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Molecular Mechanisms ◽  
Electron Flow ◽  
Red Light ◽  
Cyclic Electron Flow ◽  
Photosynthetic Oxygen Evolution ◽  
Absorption Region ◽  
Photosynthetic Oxygen ◽  
Light Flashes

Abstract Photosynthetic oxygen evolution from photosystem II particles was analyzed as consequence of a train of short (5 μs) flashes of different light quality and different intensities to study cyclic electron flow around photosystem II. Damped oscillations of the amplitudes of O2-evolution corresponding to a flash sequence were fitted numerically and analyzed in terms of a nonhomogeneous distribution of misses, represented by the probability parameter αi. Application of red light, known to promote cyclic electron flow around photosystem II (Gruszecki et al., 1995) results in a considerable increase of all αi, indicating that at the molecular level the misses may be interpreted as resulting from a competition for the reduction of oxidized P680 between cyclic electron flow and the electron flow coming from the water splitting enzyme. In accordance with previous findings, application of light flashes of the spectrum covering the absorption region of carotenoids resulted in an inhibition of cyclic electron flow and a pronounced decrease of the level of the miss parameter. Possible molecular mechanisms for the activity control of this cyclic electron transport around photosystem II by carotenoids are discussed.

Action of Methylthiopyrimidine Experimental Herbicides as Diuron-Like Inhibitors of Photosynthesis

1985 ◽  
Vol 40 (5-6) ◽  
pp. 388-390 ◽  
Author(s):  
Jean-M arc Ducruet ◽  
René Scalla
Keyword(s):  
Binding Site ◽  
Electron Flow ◽  
Fluorescence Induction ◽  
Site Structure ◽  
Structure Activity Relationships ◽  
Induction Kinetics ◽  
Fluorescence Induction Kinetics ◽  
Structure Activity ◽  
Derivatives Of ◽  
Steric Hindrances

Abstract Derivatives of 6-chloro-5-methylthiopyrimidines provide potent inhibitors of the photosynthe­tic electron flow, which act like Diuron on fluorescence induction kinetics and competitively displace it from its binding site. Structure-activity relationships show that, unlike triazines, ac­tivities of 2-or 4-alkylamino derivatives are restricted by steric hindrances. Decreases in inhibit­ory activities of these compounds observed in triazine-resistant chloroplasts are lower than de­creases reported for triazines themselves.

scholarly journals TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis

2020 ◽  
Author(s):  
Azeez Beebo ◽  
Ahmad Zia ◽  
Christopher R. Kinzel ◽  
Andrei Herdean ◽  
Karim Bouhidel ◽  
...  
Keyword(s):  
Electron Transport ◽  
Oxygen Evolution ◽  
Photosynthetic Electron Transport ◽  
Chloroplast Envelope ◽  
Photosynthetic Oxygen Evolution ◽  
Wild Type ◽  
Thylakoid Lumen ◽  
Photosynthetic Oxygen ◽  
Osmotic Treatment ◽  
Envelope Membranes

SUMMARYPhotosynthetic oxygen evolution by photosystem II requires water supply into the chloroplast to reach the thylakoid lumen. A rapid water flow is also required into the chloroplast for optimal oxygen evolution and to overcome osmotic stress. The mechanisms governing water transport in chloroplasts are largely unexplored. Previous proteomics indicated the presence of three aquaporins from the tonoplast intrinsic protein (TIP) family, TIP1;1, TIP1;2 and TIP2;1, in chloroplast membranes of Arabidopsis thaliana. Here we revisited their location and studied their role in chloroplasts. Localization experiments indicated that TIP2;1 resides in the thylakoid, whereas TIP1;2 is present in both thylakoid and envelope membranes. Mutants lacking TIP1;2 and/or TIP2;1 did not display a macroscopic phenotype when grown under standard conditions. The mutant chloroplasts and thylakoids underwent less volume changes than the corresponding wild type preparations upon osmotic treatment and in the light. Significantly reduced rates of photosynthetic electron transport were obtained in the mutant leaves, with implications on the CO2 fixation rates. However, electron transport rates did not significantly differ between mutants and wild type when isolated thylakoids were examined. Less acidification of the thylakoid lumen was measured in mutants thylakoids, resulting in a slower induction of delta pH-dependent photoprotective mechanisms. These results identify TIP1;2 and TIP2;1 as chloroplast proteins and highlight their importance for osmoregulation and optimal photosynthesis. A third aquaporin, TIP1;1, is present in the chloroplast envelope, and may play role in photosynthesis under excessive light conditions, as based on the weak photosynthetic phenotype of its mutant.

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