scholarly journals Diel Variations of Extracellular Microcystin Influence the Subcellular Dynamics of RubisCO in Microcystis aeruginosa PCC 7806

2021 ◽  
Vol 9 (6) ◽  
pp. 1265
Author(s):  
Arthur Guljamow ◽  
Tino Barchewitz ◽  
Rebecca Große ◽  
Stefan Timm ◽  
Martin Hagemann ◽  
...  
Keyword(s):  
Carbon Metabolism ◽  
Continuous Light ◽  
Fast Response ◽  
High Light ◽  
Metabolic Flexibility ◽  
Low Carbon ◽  
Intracellular Proteins ◽  
Diel Variations ◽  
Cell Densities ◽  
Intracellular Targets

The ubiquitous freshwater cyanobacterium Microcystis is remarkably successful, showing a high tolerance against fluctuations in environmental conditions. It frequently forms dense blooms which can accumulate significant amounts of the hepatotoxin microcystin, which plays an extracellular role as an infochemical but also acts intracellularly by interacting with proteins of the carbon metabolism, notably with the CO2 fixing enzyme RubisCO. Here we demonstrate a direct link between external microcystin and its intracellular targets. Monitoring liquid cultures of Microcystis in a diel experiment revealed fluctuations in the extracellular microcystin content that correlate with an increase in the binding of microcystin to intracellular proteins. Concomitantly, reversible relocation of RubisCO from the cytoplasm to the cell’s periphery was observed. These variations in RubisCO localization were especially pronounced with cultures grown at higher cell densities. We replicated these effects by adding microcystin externally to cultures grown under continuous light. Thus, we propose that microcystin may be part of a fast response to conditions of high light and low carbon that contribute to the metabolic flexibility and the success of Microcystis in the field.

scholarly journals Gradual Response of Cyanobacterial Thylakoids to Acute High-Light Stress—Importance of Carotenoid Accumulation

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1916
Author(s):  
Myriam Canonico ◽  
Grzegorz Konert ◽  
Aurélie Crepin ◽  
Barbora Šedivá ◽  
Radek Kaňa
Keyword(s):  
Single Cell ◽  
Thylakoid Membrane ◽  
Intermediate Phase ◽  
Light Stress ◽  
Fast Response ◽  
High Light ◽  
Photochemical Quenching ◽  
Second Phase ◽  
Ros Scavenging ◽  
Non Photochemical Quenching

Light plays an essential role in photosynthesis; however, its excess can cause damage to cellular components. Photosynthetic organisms thus developed a set of photoprotective mechanisms (e.g., non-photochemical quenching, photoinhibition) that can be studied by a classic biochemical and biophysical methods in cell suspension. Here, we combined these bulk methods with single-cell identification of microdomains in thylakoid membrane during high-light (HL) stress. We used Synechocystis sp. PCC 6803 cells with YFP tagged photosystem I. The single-cell data pointed to a three-phase response of cells to acute HL stress. We defined: (1) fast response phase (0–30 min), (2) intermediate phase (30–120 min), and (3) slow acclimation phase (120–360 min). During the first phase, cyanobacterial cells activated photoprotective mechanisms such as photoinhibition and non-photochemical quenching. Later on (during the second phase), we temporarily observed functional decoupling of phycobilisomes and sustained monomerization of photosystem II dimer. Simultaneously, cells also initiated accumulation of carotenoids, especially ɣ–carotene, the main precursor of all carotenoids. In the last phase, in addition to ɣ-carotene, we also observed accumulation of myxoxanthophyll and more even spatial distribution of photosystems and phycobilisomes between microdomains. We suggest that the overall carotenoid increase during HL stress could be involved either in the direct photoprotection (e.g., in ROS scavenging) and/or could play an additional role in maintaining optimal distribution of photosystems in thylakoid membrane to attain efficient photoprotection.

scholarly journals Inorganic, Organic, and Perovskite Halides with Nanotechnology for High–Light Yield X- and γ-ray Scintillators

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 88 ◽  
Author(s):  
Francesco Maddalena ◽  
Liliana Tjahjana ◽  
Aozhen Xie ◽  
Arramel ◽  
Shuwen Zeng ◽  
...  
Keyword(s):  
High Energy Physics ◽  
Low Cost ◽  
Light Yield ◽  
Fast Response ◽  
High Energy ◽  
High Light ◽  
Scintillation Light ◽  
High Light Yield ◽  
Halide Perovskites ◽  
Lead Halide

Trends in scintillators that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspections are reviewed. First, we address traditional inorganic and organic scintillators with respect of limitation in the scintillation light yields and lifetimes. The combination of high–light yield and fast response can be found in Ce 3 + , Pr 3 + and Nd 3 + lanthanide-doped scintillators while the maximum light yield conversion of 100,000 photons/MeV can be found in Eu 3 + doped SrI 2 . However, the fabrication of those lanthanide-doped scintillators is inefficient and expensive as it requires high-temperature furnaces. A self-grown single crystal using solution processes is already introduced in perovskite photovoltaic technology and it can be the key for low-cost scintillators. A novel class of materials in scintillation includes lead halide perovskites. These materials were explored decades ago due to the large X-ray absorption cross section. However, lately lead halide perovskites have become a focus of interest due to recently reported very high photoluminescence quantum yield and light yield conversion at low temperatures. In principle, 150,000–300,000 photons/MeV light yields can be proportional to the small energy bandgap of these materials, which is below 2 eV. Finally, we discuss the extraction efficiency improvements through the fabrication of the nanostructure in scintillators, which can be implemented in perovskite materials. The recent technology involving quantum dots and nanocrystals may also improve light conversion in perovskite scintillators.

scholarly journals Response of CO 2 -starved diatom Phaeodactylum tricornutum to light intensity transition

2017 ◽  
Vol 372 (1728) ◽  
pp. 20160396 ◽  
Author(s):  
Parisa Heydarizadeh ◽  
Wafâa Boureba ◽  
Morteza Zahedi ◽  
Bing Huang ◽  
Brigitte Moreau ◽  
...  
Keyword(s):  
Flux Density ◽  
Carbon Metabolism ◽  
Phaeodactylum Tricornutum ◽  
Shikimate Pathway ◽  
Aromatic Amino Acids ◽  
Molecular Data ◽  
High Light ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Low Light

In this study, we investigated the responses of Phaeodactylum tricornutum cells acclimated to 300 µmol m −2 s −1 photon flux density to an increase (1000 µmol m −2 s −1 ) or decrease (30 µmol m −2 s −1 ) in photon flux densities. The light shift occurred abruptly after 5 days of growth and the acclimation to new conditions was followed during the next 6 days at the physiological and molecular levels. The molecular data reflect a rearrangement of carbon metabolism towards the production of phosphoenolpyruvic acid (PEP) and/or pyruvate. These intermediates were used differently by the cell as a function of the photon flux density: under low light, photosynthesis was depressed while respiration was increased. Under high light, lipids and proteins accumulated. Of great interest, under high light, the genes coding for the synthesis of aromatic amino acids and phenolic compounds were upregulated suggesting that the shikimate pathway was activated. This article is part of the themed issue ‘The peculiar carbon metabolism in diatoms’.

Leaf chlorosis and carbon metabolism of eggplant in response to continuous light and carbon dioxide

1996 ◽  
Vol 67 (1-2) ◽  
pp. 27-37 ◽  
Author(s):  
Ephraim N. Murage ◽  
Noriko Watashiro ◽  
Masaharu Masuda
Keyword(s):  
Carbon Dioxide ◽  
Carbon Metabolism ◽  
Continuous Light ◽  
Leaf Chlorosis

scholarly journals Potentialities of hydrogen enriched natural gas for residential heating decarbonization and impact analysis on premixed boilers

2019 ◽  
Vol 116 ◽  
pp. 00072 ◽  
Author(s):  
Fabio Schiro ◽  
Anna Stoppato ◽  
Alberto Benato
Keyword(s):  
Natural Gas ◽  
Impact Analysis ◽  
Hydrogen Generation ◽  
Energy System ◽  
Fast Response ◽  
Primary Role ◽  
Low Carbon ◽  
Gaseous Fuels ◽  
Viable Solution ◽  
The Impact

Nowadays, decarbonization of energy economy is a topical theme and several pathways are under discussion. Gaseous fuels will play a primary role during this transition, and the production of renewable or low carbon-impact gaseous fuels is necessary to deal with this challenge. Decarbonization will be sustained by an increasing share of renewables, which production intermittency can be critical for the energy system. Renewable hydrogen generation is a viable solution since this energy vector can be produced from electricity with a fast response and injected in the existing natural gas infrastructures, granting storage capacity and easy transport. Parallelly to the renewable-based energy production, fossil-based energy can be exploited with a low carbon impact, using methane from reservoirs to produce hydrogen capturing CO2. The mentioned scenarios will lead to hydrogen enrichment of natural gas, which impact on the infrastructures is being actively studied. The effect on end-user devices, instead, is poorly analysed, but is fundamental to be assessed. This paper highlights the impact on the widely used premixed condensing boilers, which will be fired with hydrogen enriched natural gas in the near future, and the changes required to components.

scholarly journals Ce3+ activated LaBr3−xIx: High-light-yield and fast-response mixed halide scintillators

2008 ◽  
Vol 103 (10) ◽  
pp. 103517 ◽  
Author(s):  
M. D. Birowosuto ◽  
P. Dorenbos ◽  
K. W. Krämer ◽  
H. U. Güdel
Keyword(s):  
Light Yield ◽  
Fast Response ◽  
High Light ◽  
High Light Yield

scholarly journals Physiological limits to life in anoxic subseafloor sediment

2020 ◽  
Vol 44 (2) ◽  
pp. 219-231 ◽  
Author(s):  
William D Orsi ◽  
Bernhard Schink ◽  
Wolfgang Buckel ◽  
William F Martin
Keyword(s):  
Cell Protein ◽  
Energetic Cost ◽  
Dead Cell ◽  
Low Carbon ◽  
Atp Production ◽  
Physiological Limits ◽  
Cell Biomass ◽  
Production And Consumption ◽  
Acetoclastic Methanogenesis ◽  
Cell Densities

ABSTRACT In subseafloor sediment, microbial cell densities exponentially decrease with depth into the fermentation zone. Here, we address the classical question of 'why are cells dying faster than they are growing?’ from the standpoint of physiology. The stoichiometries of fermentative ATP production and consumption in the fermentation zone place bounds on the conversion of old cell biomass into new. Most fermentable organic matter in deep subseafloor sediment is amino acids from dead cells because cells are mostly protein by weight. Conversion of carbon from fermented dead cell protein into methanogen protein via hydrogenotrophic and acetoclastic methanogenesis occurs at ratios of ∼200:1 and 100:1, respectively, while fermenters can reach conversion ratios approaching 6:1. Amino acid fermentations become thermodynamically more efficient at lower substrate and product concentrations, but the conversion of carbon from dead cell protein into fermenter protein is low because of the high energetic cost of translation. Low carbon conversion factors within subseafloor anaerobic feeding chains account for exponential declines in cellular biomass in the fermentation zone of anoxic sediments. Our analysis points to the existence of a life–death transition zone in which the last biologically catalyzed life processes are replaced with purely chemical reactions no longer coupled to life.

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