scholarly journals The role of Arabidopsis thaliana photoreceptors in regulating the process of state transitions

2021 ◽  
Vol 11 (2) ◽  
pp. 251-259
Author(s):  
V. I. Belkov ◽  
K. E. Belogub ◽  
E. Yu. Garnik ◽  
V. I. Tarasenko ◽  
Yu. M. Konstantinov
Keyword(s):  
Arabidopsis Thaliana ◽  
Redox Regulation ◽  
Photosynthetic Apparatus ◽  
The State ◽  
State Transitions ◽  
Adaptation Mechanism ◽  
Active Forms Of Oxygen ◽  
Variable Factor ◽  
Cryptochrome 1

The initial formation of the photosynthetic apparatus in plants occurs during photomorphogenesis. The red/far-red (phytochromes) and blue (cryptochrome) light protein-photoreceptors play the most important role in photomorphogenesis initiation and regulation. The exited phytochrome and cryptochrome molecules can interact with transcription factors, changing the expression of nuclear genes, which encode the proteins of the plant photosynthetic apparatus. Since light is a variable factor, plants have developed appropriate adaptation mechanisms, including their photosynthetic apparatus protection. The mechanism of state transitions ensures a rapid adaptation of the photosynthetic apparatus. This adaptation mechanism increases the adsorption efficiency under current light conditions and prevents intensive generation of active forms of oxygen in chloroplasts, which leads to photo-oxidation and even cell death. This work aims to determine the role of photoreceptors - phytochromes A and B, as well as cryptochrome 1 and 2 - in regulating the process of state transitions in the Arabidopsis thaliana model plant. Arabidopsis mutants with the defects on A and B phytochromes and cryptochrome 1 and 2 genes were used as the research objects. The blue native electrophoresis in polyacrylamide gel was used to visualise state transitions. It was found that these photoreceptors had no direct effect on the redox-regulation of the state transitions mechanism in Arabidopsis. Presumably, these photoreceptors protect the photosynthetic apparatus from excessive light not by regulating the state transitions but indirectly, through regulating the chlorophyll, carotenoid and antioxidant components content.

scholarly journals Melatonin Enhanced the Tolerance of Arabidopsis thaliana to High Light Through Improving Anti-oxidative System and Photosynthesis

2021 ◽  
Vol 12 ◽  
Author(s):  
Si-Jia Yang ◽  
Bo Huang ◽  
Yu-Qing Zhao ◽  
Di Hu ◽  
Tao Chen ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Light Stress ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Protective Effects ◽  
Biotic And Abiotic Stresses ◽  
Exogenous Melatonin ◽  
Sunlight Intensity ◽  
Oxidative System

Land plants live in a crisis-filled environment and the fluctuation of sunlight intensity often causes damage to photosynthetic apparatus. Phyto-melatonin is an effective bioactive molecule that helps plants to resist various biotic and abiotic stresses. In order to explore the role of melatonin under high light stress, we investigated the effects of melatonin on anti-oxidative system and photosynthesis of Arabidopsis thaliana under high light. Results showed that exogenous melatonin increased photosynthetic rate and protected photosynthetic proteins under high light. This was mainly owing to the fact that exogenous melatonin effectively decreased the accumulation of reactive oxygen species and protected integrity of membrane and photosynthetic pigments, and reduced cell death. Taken together, our study promoted more comprehensive understanding in the protective effects of exogenous melatonin under high light.

Schizophrenia as a Disorder of Cerebral State Transition

1986 ◽  
Vol 20 (2) ◽  
pp. 167-178 ◽  
Author(s):  
J. J. Wright ◽  
R. R. Kydd
Keyword(s):  
State Transition ◽  
Finite State Machines ◽  
The State ◽  
State Transitions ◽  
Brain State ◽  
State Machines ◽  
Electrocortical Activity ◽  
Wave Nature ◽  
Finite State

This paper offers a speculative consideration of the schizophrenic process in the light of recent findings concerning the wave nature of electrocortical activity. These findings indicate that changes of brain state can be described in the terminology of finite-state machines, and both the instantaneous states and the state transitions can be specified. It is suggested that the mental phenomena of schizophrenia may be reducible to events (some specific type of instability) which could be observed by appropriate analytic techniques applied to EEG. Present empirical EEG findings in schizophrenics are reviewed in this light, and the role of dopamine blockade in treatment is also considered.

scholarly journals The Role of Cysteine Residues in Redox Regulation and Protein Stability of Arabidopsis thaliana Starch Synthase 1

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0136997 ◽  
Author(s):  
Katsiaryna Skryhan ◽  
Jose A. Cuesta-Seijo ◽  
Morten M. Nielsen ◽  
Lucia Marri ◽  
Silas B. Mellor ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Protein Stability ◽  
Redox Regulation ◽  
Starch Synthase ◽  
Cysteine Residues

Macroorganisation and flexibility of thylakoid membranes

2019 ◽  
Vol 476 (20) ◽  
pp. 2981-3018 ◽  
Author(s):  
Petar H. Lambrev ◽  
Parveen Akhtar
Keyword(s):  
Light Harvesting ◽  
Current Knowledge ◽  
Three Dimensional ◽  
Photosynthetic Apparatus ◽  
Dynamic Responses ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

Activation of cytochrome c to a peroxidase compound I-type intermediate by H2O2: relevance to redox signalling in apoptosis

2004 ◽  
Vol 71 ◽  
pp. 97-106 ◽  
Author(s):  
Mark Burkitt ◽  
Clare Jones ◽  
Andrew Lawrence ◽  
Peter Wardman
Keyword(s):  
Cytochrome C ◽  
Hydroxyl Radical ◽  
Redox Regulation ◽  
Chemotherapeutic Agents ◽  
Tyrosyl Radical ◽  
Compound I ◽  
Definitive Evidence ◽  
Enhanced Production ◽  
Physico Chemical

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.

A Re-Appraisal of the Role of Blood Coagulation and Platelets in the Generalized Shwartzman Phenomenon

1966 ◽  
Vol 15 (03/04) ◽  
pp. 519-538 ◽  
Author(s):  
J Levin ◽  
E Beck
Keyword(s):  
Blood Coagulation ◽  
The State ◽  
Coagulation System ◽  
Renal Lesions ◽  
Intravascular Coagulation ◽  
Renal Glomeruli ◽  
Coagulation Mechanism ◽  
Shwartzman Phenomenon ◽  
Do So

SummaryThe role of intravascular coagulation in the production of the generalized Shwartzman phenomenon has been evaluated. The administration of endotoxin to animals prepared with Thorotrast results in activation of the coagulation mechanism with the resultant deposition of fibrinoid material in the renal glomeruli. Anticoagulation prevents alterations in the state of the coagulation system and inhibits development of the renal lesions. Platelets are not primarily involved. Platelet antiserum produces similar lesions in animals prepared with Thorotrast, but appears to do so in a manner which does not significantly involve intravascular coagulation.The production of adrenal cortical hemorrhage, comparable to that seen in the Waterhouse-Friderichsen syndrome, following the administration of endotoxin to animals that had previously received ACTH does not require intravascular coagulation and may not be a manifestation of the generalized Shwartzman phenomenon.

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