scholarly journals In vivo assessment of mitochondrial respiratory alternative oxidase activity and cyclic electron flow around photosystem I on small coral fragments

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Félix Vega de Luna ◽  
Juan José Córdoba-Granados ◽  
Kieu-Van Dang ◽  
Stéphane Roberty ◽  
Pierre Cardol
Keyword(s):  
Photosystem I ◽  
Alternative Oxidase ◽  
Environmental Changes ◽  
Electron Flow ◽  
High Light ◽  
Cyclic Electron Flow ◽  
Active Centers ◽  
Time Resolved ◽  
Stylophora Pistillata

Abstract The mutualistic relationship existing between scleractinian corals and their photosynthetic endosymbionts involves a complex integration of the metabolic pathways within the holobiont. Respiration and photosynthesis are the most important of these processes and although they have been extensively studied, our understanding of their interactions and regulatory mechanisms is still limited. In this work we performed chlorophyll-a fluorescence, oxygen exchange and time-resolved absorption spectroscopy measurements on small and thin fragments (0.3 cm2) of the coral Stylophora pistillata. We showed that the capacity of mitochondrial alternative oxidase accounted for ca. 25% of total coral respiration, and that the high-light dependent oxygen uptake, commonly present in isolated Symbiodiniaceae, was negligible. The ratio between photosystem I (PSI) and photosystem II (PSII) active centers as well as their respective electron transport rates, indicated that PSI cyclic electron flow occurred in high light in S. pistillata and in some branching and lamellar coral species freshly collected in the field. Altogether, these results show the potential of applying advanced biophysical and spectroscopic methods on small coral fragments to understand the complex mechanisms of coral photosynthesis and respiration and their responses to environmental changes.

scholarly journals PsaE Is Required for in Vivo Cyclic Electron Flow around Photosystem I in the Cyanobacterium Synechococcus sp. PCC 7002

1993 ◽  
Vol 103 (1) ◽  
pp. 171-180 ◽  
Author(s):  
L. Yu ◽  
J. Zhao ◽  
U. Muhlenhoff ◽  
D. A. Bryant ◽  
J. H. Golbeck
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Synechococcus Sp

Partially Dissecting Electron Fluxes in Both Photosystems in Spinach Leaf Disks during Photosynthetic Induction

2019 ◽  
Vol 60 (10) ◽  
pp. 2206-2219 ◽  
Author(s):  
Meng-Meng Zhang ◽  
Da-Yong Fan ◽  
Keach Murakami ◽  
Murray R Badger ◽  
Guang-Yu Sun ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Electron Flow ◽  
Transport Processes ◽  
Cyclic Electron Flow ◽  
Fine Tuning ◽  
Photosynthetic Induction ◽  
Strong Light ◽  
Spinach Leaf ◽  
Leaf Disks

Abstract Photosynthetic induction, a gradual increase in photosynthetic rate on a transition from darkness or low light to high light, has ecological significance, impact on biomass accumulation in fluctuating light and relevance to photoprotection in strong light. However, the experimental quantification of the component electron fluxes in and around both photosystems during induction has been rare. Combining optimized chlorophyll fluorescence, the redox kinetics of P700 [primary electron donor in Photosystem I (PSI)] and membrane inlet mass spectrometry in the absence/presence of inhibitors/mediator, we partially estimated the components of electron fluxes in spinach leaf disks on transition from darkness to 1,000 �mol photons�m−2�s−1 for up to 10 min, obtaining the following findings: (i) the partitioning of energy between both photosystems did not change noticeably; (ii) in Photosystem II (PSII), the combined cyclic electron flow (CEF2) and charge recombination (CR2) to the ground state decreased gradually toward 0 in steady state; (iii) oxygen reduction by electrons from PSII, partly bypassing PSI, was small but measurable; (iv) cyclic electron flow around PSI (CEF1) peaked before becoming somewhat steady; (v) peak magnitudes of some of the electron fluxes, all probably photoprotective, were in the descending order: CEF1 > CEF2 + CR2 > chloroplast O2 uptake; and (vi) the chloroplast NADH dehydrogenase-like complex appeared to aid the antimycin A-sensitive CEF1. The results are important for fine-tuning in silico simulation of in vivo photosynthetic electron transport processes; such simulation is, in turn, necessary to probe partial processes in a complex network of interactions in response to environmental changes.

scholarly journals Impaired Cyclic Electron Flow around Photosystem I Disturbs High-Light Respiratory Metabolism

2016 ◽  
Vol 172 (4) ◽  
pp. 2176-2189 ◽  
Author(s):  
Igor Florez-Sarasa ◽  
Ko Noguchi ◽  
Wagner L. Araújo ◽  
Ana Garcia-Nogales ◽  
Alisdair R. Fernie ◽  
...  
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
High Light ◽  
Cyclic Electron Flow ◽  
Respiratory Metabolism

Inhibition of Photosynthetic Electron Transport by Halogenated 4-Hydroxy-pyridines

1985 ◽  
Vol 40 (5-6) ◽  
pp. 391-399 ◽  
Author(s):  
A. Trebst ◽  
B. Depka ◽  
S. M. Ridley ◽  
A. F. Hawkins
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Essential Element ◽  
Photosynthetic Electron Transport ◽  
Cyclic Electron Flow ◽  
Acceptor Side

Abstract Herbicidal halogen substituted 4-hydroxypyridines are inhibitors of photosynthetic electron flow in isolated thylakoid membranes by interfering with the acceptor side of photosystem II. Tetrabromo-4-hydroxypyridine, the most active compound found, has a pI50-value of 7.6 in the inhibition of oxygen evolution in both the reduction of an acceptor of photosystem I and an acceptor of photosystem II. The new inhibitors displace both metribuzin and ioxynil from the membrane. The 4-hydroxypyridines, like ioxynil, have unimpaired inhibitor potency in Tristreated chloroplasts, whereas the DCMU-type family of herbicides does not. It is suggested that 4-hydroxypyridines are complementary to phenol-type inhibitors, and a common essential element is proposed. The 4-hydroxypyridines do not inhibit photosystem I or non-cyclic electron flow through the cytochrome b/f complex. But they do have a second inhibition site in photosynthetic electron transport since they inhibit ferredoxin-catalyzed cyclic electron flow, indicating an antimycin-like property. A comparison of the in vitro potency of the compounds with the in vivo potency shows no correlation. A major herbicidal mode of action of the group is related to the inhibition of carotenoid synthesis, and access to the chloroplast lamellae in vivo for inhibition of electron transport may be restricted.

Cyclic electron flow around photosystem I is enhanced at low pH

2014 ◽  
Vol 83 ◽  
pp. 194-199 ◽  
Author(s):  
Teena Tongra ◽  
Sudhakar Bharti ◽  
Anjana Jajoo
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
Low Ph ◽  
Cyclic Electron Flow
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