scholarly journals CO2 supply modulates lipid remodelling, photosynthetic and respiratory activities in Chlorella species

2021 ◽  
Author(s):  
Michela Cecchin ◽  
Matteo Paloschi ◽  
Giovanni Busnardo ◽  
Stefano Cazzaniga ◽  
Stephan Cuine ◽  
...  
Keyword(s):  
Redox State ◽  
Dark Respiration ◽  
Photosynthetic Apparatus ◽  
Model Organism ◽  
Reducing Power ◽  
Biomass Accumulation ◽  
Metabolic Responses ◽  
Translational Repressor ◽  
Carbon Supply ◽  
Chlorella Species

ABSTRACTMicroalgae represent potential solutions to reduce the atmospheric CO2 level through photosynthesis. To boost CO2 fixation by microalgae it is essential to understand physiologic and metabolic responses at the base of CO2 assimilation and carbon flow. In this work two Trebouxiophyceae species, Chlorella sorokiniana and Chlorella vulgaris, were investigated for their metabolic responses to high and low CO2 (air level) availability. High CO2 availability resulted in an increase in biomass accumulation in both species but with a different chloroplast and mitochondrial responses. In C. sorokiniana we observed increased polar lipids and protein amount and a balanced NADPH redox state and a similar total respiration in the two conditions analysed. In contrast, in C. vulgaris high CO2 level caused an increase in TAG accumulation and a higher NADPH consumption suggesting a CO2 dependent increase of reducing power consumption in the chloroplast, which in turn influences the redox state of the mitochondria by lowering total dark respiration. Several rearrangements of the photosynthetic machinery were observed in both species, which differ from those described for the model organism Chlamydomonas reinhardtii. In the case of C. reinhardtii, adaptation of the photosynthetic apparatus to different CO2 availability relies on the translational repressor NAB1. NAB1 homologous protein could be identified only in C. vulgaris but lacked the regulation mechanisms previously described in C. reinhardtii. These findings highlight that the acclimation strategies to cope with a fluctuating inorganic carbon supply are diverse among green microalgae and point to new biotechnological strategies to boost CO2 fixation.One sentence summaryHigh/low CO2 availability induces cell responses as lipids remodelling, adaptations of the photosynthetic apparatus and modulation of mitochondrial respiration not conserved among green algae

Analysis of the effects of the spotted tentiform leafminer (Phyllonorycter blancardella) on the photosynthetic characteristics of apple leaves

1982 ◽  
Vol 60 (12) ◽  
pp. 2734-2740 ◽  
Author(s):  
J. T. A. Proctor ◽  
J. M. Bodnar ◽  
W. J. Blackburn ◽  
R. L. Watson
Keyword(s):  
Photosynthetic Rate ◽  
Dark Respiration ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
Light Response ◽  
Apple Leaves ◽  
Economic Thresholds ◽  
Fluorescence Reading ◽  
Use Efficiency ◽  
High Fluorescence

Infestation of apple leaves with the spotted tentiform leafminer (STLM) reduced their net photosynthetic rate (Pn) over a range of light intensities. At a saturating irradiance level of 1240 μE∙m−2∙s−1 and 20 mines per leaf, 32.9% of the leaf area was injured but Pn was decreased by only 23.2%. Examination of parameters in a model for leaf photosynthesis showed a reduction in maximum photosynthetic rate (asymptotic value of the light-response curve) and mesophyll conductance but not in photochemical efficiency or dark respiration. The STLM injury had no effect on transpiration, stomatal conductance, and a slight effect on internal CO2 concentration and water-use efficiency. Mining reduced chlorophyll content of the leaves and this reduced the chlorophyll fluorescence of the mined areas. Tissue around the mines had a relatively high fluorescence reading confirming the Pn measurements and suggesting that this technique was suitable for these and similar studies. Mining by the STLM disrupts the photosynthetic apparatus of the leaf and affects a number of mechanisms in the photosynthetic process. Correlating these effects with field observations will help in determining economic thresholds for this insect.

scholarly journals High light alongside elevated PCO2 alleviates thermal depression of photosynthesis in a hard coral (Pocillopora acuta)

2020 ◽  
Vol 223 (20) ◽  
pp. jeb223198
Author(s):  
Robert A. B. Mason ◽  
Christopher B. Wall ◽  
Ross Cunning ◽  
Sophie Dove ◽  
Ruth D. Gates
Keyword(s):  
Elevated Temperature ◽  
Ocean Acidification ◽  
Environmental Changes ◽  
Dark Respiration ◽  
Interactive Effect ◽  
Light Availability ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Photochemical Quenching ◽  
Strong Light

ABSTRACTThe absorbtion of human-emitted CO2 by the oceans (elevated PCO2) is projected to alter the physiological performance of coral reef organisms by perturbing seawater chemistry (i.e. ocean acidification). Simultaneously, greenhouse gas emissions are driving ocean warming and changes in irradiance (through turbidity and cloud cover), which have the potential to influence the effects of ocean acidification on coral reefs. Here, we explored whether physiological impacts of elevated PCO2 on a coral–algal symbiosis (Pocillopora acuta–Symbiodiniaceae) are mediated by light and/or temperature levels. In a 39 day experiment, elevated PCO2 (962 versus 431 µatm PCO2) had an interactive effect with midday light availability (400 versus 800 µmol photons m−2 s−1) and temperature (25 versus 29°C) on areal gross and net photosynthesis, for which a decline at 29°C was ameliorated under simultaneous high-PCO2 and high-light conditions. Light-enhanced dark respiration increased under elevated PCO2 and/or elevated temperature. Symbiont to host cell ratio and chlorophyll a per symbiont increased at elevated temperature, whilst symbiont areal density decreased. The ability of moderately strong light in the presence of elevated PCO2 to alleviate the temperature-induced decrease in photosynthesis suggests that higher substrate availability facilitates a greater ability for photochemical quenching, partially offsetting the impacts of high temperature on the photosynthetic apparatus. Future environmental changes that result in moderate increases in light levels could therefore assist the P. acuta holobiont to cope with the ‘one–two punch’ of rising temperatures in the presence of an acidifying ocean.

scholarly journals LmTDRM Database: A Comprehensive Database on Thiol Metabolic Gene/Gene Products in Listeria monocytogenes EGDe

2014 ◽  
Vol 11 (1) ◽  
pp. 17-29
Author(s):  
Vanishree Srinivas ◽  
Shubha Gopal
Keyword(s):  
Oxidative Stress ◽  
Listeria Monocytogenes ◽  
Protein Function ◽  
Model Organism ◽  
Reducing Power ◽  
Major Step ◽  
Redox Metabolism ◽  
Interaction Database ◽  
Insertion Elements ◽  
Thiol Redox

Summary There are a number of databases on the Listeria species and about their genome. However, these databases do not specifically address a set of network that is important in defence mechanism of the bacteria. Listeria monocytogenes EGDe is a well-established intracellular model organism to study host pathogenicity because of its versatility in the host environment. Here, we have focused on thiol disulphide redox metabolic network proteins, specifically in L. monocytogenes EGDe. The thiol redox metabolism is involved in oxidative stress mechanism and is found in all living cells. It functions to maintain the thiol disulphide balance required for protein folding by providing reducing power. Nevertheless, they are involved in the reversible oxidation of thiol groups in biomolecules by creating disulphide bonds; therefore, the term thiol disulphide redox metabolism (TDRM). TDRM network genes play an important role in oxidative stress mechanism and during host-pathogen interaction. Therefore, it is essential to have detailed information on these proteins with regard to other bacteria and its genome analysis to understand the presence of tRNA, transposons, and insertion elements for horizontal gene transfer. LmTDRM database is a new comprehensive web-based database on thiol proteins and their functions. It includes: Description, Search, TDRM analysis, and genome viewer. The quality of these data has been evaluated before they were aggregated to produce a final representation. The web interface allows for various queries to understand the protein function and their annotation with respect to their relationship with other bacteria. LmTDRM is a major step towards the development of databases on thiol disulphide redox proteins; it would definitely help researchers to understand the mechanism of these proteins and their interaction. Database URL: www.lmtdrm.com

Changes in photosynthetic parameters and antioxidant activities following heat-shock treatment in tomato plants

2006 ◽  
Vol 33 (2) ◽  
pp. 177 ◽  
Author(s):  
Daymi Camejo ◽  
Ana Jiménez ◽  
Juan José Alarcón ◽  
Walfredo Torres ◽  
Juana María Gómez ◽  
...  
Keyword(s):  
Heat Shock ◽  
Antioxidant Activities ◽  
Dark Respiration ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Parameters ◽  
Tomato Plants ◽  
Shock Temperature ◽  
Oxidative Processes ◽  
Gas Exchange Characteristics ◽  
Chlorophyll Photooxidation

Seedlings of two tomato genotypes, Lycopersicon esculentum Mill. var. Amalia and the wild thermotolerant type Nagcarlang, were grown under a photoperiod of 16 h light at 25°C and 8 h dark at 20°C. At the fourth true leaf stage, a group of plants were exposed to a heat-shock temperature of 45°C for 3 h, and measurements of chlorophyll fluorescence, gas-exchange characteristics, dark respiration and oxidative and antioxidative parameters were made after releasing the stress. The heat shock induced severe alterations in the photosynthesis of Amalia that seem to mitigate the damaging impact of high temperatures by lowering the leaf temperature and maintaining stomatal conductance and more efficient maintenance of antioxidant capacity, including ascorbate and glutathione levels. These effects were not evident in Nagcarlang. In Amalia plants, a larger increase in dark respiration also occurred in response to heat shock and the rates of the oxidative processes were higher than in Nagcarlang. This suggests that heat injury in Amalia may involve chlorophyll photooxidation mediated by activated oxygen species (AOS) and more severe alterations in the photosynthetic apparatus. All these changes could be related to the more dramatic effect of heat shock seen in Amalia than in Nagcarlang plants.

Thermal acclimation of photosynthesis by the arctic plant Saxifraga cernua

1986 ◽  
Vol 64 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Bruce T. Mawson ◽  
Josef Svoboda ◽  
Raymond W. Cummins
Keyword(s):  
Low Temperature ◽  
Growth Temperature ◽  
Dark Respiration ◽  
Photosynthetic Apparatus ◽  
Net Photosynthesis ◽  
Temperature Acclimation ◽  
The Arctic ◽  
Optimum Temperature ◽  
Whole Plants ◽  
Saxifraga Cernua

The thermal acclimations of net photosynthesis, dark respiration, and photorespiration have been studied in the arctic plant Saxifraga cernua. The gas exchange of whole plants grown to maturity under different temperature regimes was analysed for individual plants transferred from (i) 10 to 20 (referred to as high-temperature acclimation) and (ii) 20 to 5 °C (low-temperature acclimation). High- and low-temperature acclimation resulted in shifts of the leaf temperature optimum for net photosynthesis of whole plants in the direction of the new growth temperature. That the acclimating temperature directly affected the photosynthetic apparatus was indicated by (i) changes in the optimum temperature for gross photosynthesis of whole plants and (ii) a change in the oxygen sensitivity of net photosynthesis after acclimation to a new growth temperature. The change in the optimum temperature for net photosynthesis was also due, in part, to altered dark respiration rates which increased during acclimation to low growth temperatures. These results suggest that such acclimation in arctic species like S. cernua arose as a result of the selective pressure of fluctuating temperatures which are experienced during the growth season to maximize annual growth under arctic and subarctic conditions.

scholarly journals Genes Required for Survival in Microgravity Revealed by Genome-Wide Yeast Deletion Collections Cultured during Spaceflight

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Corey Nislow ◽  
Anna Y. Lee ◽  
Patricia L. Allen ◽  
Guri Giaever ◽  
Andrew Smith ◽  
...  
Keyword(s):  
Redox State ◽  
Biological Effects ◽  
Model Organism ◽  
Single Copy ◽  
Complete Collection ◽  
Dna Damaging Agents ◽  
Genome Wide ◽  
Unbiased Manner ◽  
High Concordance ◽  
Yeast Deletion

Spaceflight is a unique environment with profound effects on biological systems including tissue redistribution and musculoskeletal stresses. However, the more subtle biological effects of spaceflight on cells and organisms are difficult to measure in a systematic, unbiased manner. Here we test the utility of the molecularly barcoded yeast deletion collection to provide a quantitative assessment of the effects of microgravity on a model organism. We developed robust hardware to screen, in parallel, the complete collection of ~4800 homozygous and ~5900 heterozygous (including ~1100 single-copy deletions of essential genes) yeast deletion strains, each carrying unique DNA that acts as strain identifiers. We compared strain fitness for the homozygous and heterozygous yeast deletion collections grown in spaceflight and ground, as well as plus and minus hyperosmolar sodium chloride, providing a second additive stressor. The genome-wide sensitivity profiles obtained from these treatments were then queried for their similarity to a compendium of drugs whose effects on the yeast collection have been previously reported. We found that the effects of spaceflight have high concordance with the effects of DNA-damaging agents and changes in redox state, suggesting mechanisms by which spaceflight may negatively affect cell fitness.

Photorespiration and nitrogenase activity in the blue-green alga, Anabaena cylindrica

1972 ◽  
Vol 180 (1058) ◽  
pp. 87-102 ◽  
Keyword(s):  
Green Alga ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Dark Respiration ◽  
Reducing Power ◽  
Blue Green Alga ◽  
Anabaena Cylindrica ◽  
Oxygen Inhibition ◽  
Highly Sensitive ◽  
Photosynthetic Oxygen

Oxygen uptake in the light (photorespiration) by the nitrogen-fixing blue-green alga Anabaena cylindrica may be up to twenty times the dark respiration rate. The rate of uptake in the light increases linearly with increasing p O 2 while dark respiration is saturated at a p O 2 near 0.05 atm. Photorespiration is inhibited rapidly and completely by DCMU (3 x 10 -5 m) but KCN (10 -4 m) has little effect. Exogenously supplied hydroxyethane sulphonate (10 -5 m), an inhibitor of glycollate oxidase activity, and glycollate do not affect respiration, although 14 C-labelled glycollate is assimilated in the light and in the dark. Photorespiration is highly sensitive to p CO 2 and to NaHCO 3 concentration and approaches true photosynthetic oxygen production at the CO 2 compensation point of 10 parts/10 6 . A CO 2 concentration of 0.02 atm completely inhibits photorespiration whereas true photosynthesis is scarcely affected. Conditions which stimulate photorespiration (low p CO 2 and high p O 2 ) progressively inhibit acetylene reduction. In short-term studies DCMU inhibits acetylene reduction under condi­tions which stimulate photorespiration but has little effect under conditions which inhibit photorespiration. The results suggest that photorespiration and nitrogenase activity com­pete indirectly for reducing power and that at least one mechanism of oxygen inhibition of nitrogenase activity is via a stimulation of photorespiration.

scholarly journals NTRC-dependent redox balance of 2-Cys peroxiredoxins is needed for optimal function of the photosynthetic apparatus

2017 ◽  
Vol 114 (45) ◽  
pp. 12069-12074 ◽  
Author(s):  
Juan Manuel Pérez-Ruiz ◽  
Belén Naranjo ◽  
Valle Ojeda ◽  
Manuel Guinea ◽  
Francisco Javier Cejudo
Keyword(s):  
Redox Regulation ◽  
Photosynthetic Apparatus ◽  
Reducing Power ◽  
Redox Balance ◽  
Light Energy ◽  
Energy Utilization ◽  
Antioxidant Systems ◽  
Redox Systems ◽  
Triple Mutant ◽  
Low Efficiency

Thiol-dependent redox regulation allows the rapid adaptation of chloroplast function to unpredictable changes in light intensity. Traditionally, it has been considered that chloroplast redox regulation relies on photosynthetically reduced ferredoxin (Fd), thioredoxins (Trxs), and an Fd-dependent Trx reductase (FTR), the Fd-FTR-Trxs system, which links redox regulation to light. More recently, a plastid-localized NADPH-dependent Trx reductase (NTR) with a joint Trx domain, termed NTRC, was identified. NTRC efficiently reduces 2-Cys peroxiredoxins (Prxs), thus having antioxidant function, but also participates in redox regulation of metabolic pathways previously established to be regulated by Trxs. Thus, the NTRC, 2-Cys Prxs, and Fd-FTR-Trxs redox systems may act concertedly, but the nature of the relationship between them is unknown. Here we show that decreased levels of 2-Cys Prxs suppress the phenotype of the Arabidopsis thaliana ntrc KO mutant. The excess of oxidized 2-Cys Prxs in NTRC-deficient plants drains reducing power from chloroplast Trxs, which results in low efficiency of light energy utilization and impaired redox regulation of Calvin–Benson cycle enzymes. Moreover, the dramatic phenotype of the ntrc-trxf1f2 triple mutant, lacking NTRC and f-type Trxs, was also suppressed by decreased 2-Cys Prxs contents, as the ntrc-trxf1f2-Δ2cp mutant partially recovered the efficiency of light energy utilization and exhibited WT rate of CO2 fixation and growth phenotype. The suppressor phenotype was not caused by compensatory effects of additional chloroplast antioxidant systems. It is proposed that the Fd-FTR-Trx and NTRC redox systems are linked by the redox balance of 2-Cys Prxs, which is crucial for chloroplast function.

Adaptations of the photosynthetic apparatus of sun- and shade-grown yellow birch (Betula alleghaniensis Britt.)

1970 ◽  
Vol 48 (9) ◽  
pp. 1681-1688 ◽  
Author(s):  
K. T. Logan
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Dark Respiration ◽  
Photosynthetic Apparatus ◽  
Betula Alleghaniensis ◽  
Yellow Birch ◽  
Photosynthetic Rates ◽  
Light Intensities ◽  
Young Leaves ◽  
Sun And Shade

Rates of apparent photosynthesis and dark respiration of 4-year-old yellow birch (Betula alleghaniensis Britt.) seedlings, grown in full light and shade (13% of full light), were measured with an infrared gas analyzer. Measurements were made periodically throughout the growing season, using either attached branches or entire seedlings. Effects of light intensities from 0 to 4500 ft-c on photosynthetic rates were studied, and comparisons made between young and old leaves and between photosynthetic rates in normal (300 p.p.m.) and saturating (1245 p.p.m.) CO2 concentration.The photosynthetic apparatus of yellow birch was found to adapt poorly to shaded conditions. In saturating light, the rate of apparent photosynthesis of young leaves of shade-grown seedlings was only half that of sun-grown seedlings; for old leaves the reduction was even greater. As a result, shade-grown seedlings had a lower photosynthetic capacity in saturating light despite their larger leaf area. In low light intensities, leaves of sun- and shade-grown seedlings had nearly the same rates of apparent photosynthesis. Rates of respiration of shade-grown seedlings were one-half those of sun-grown seedlings.When seedlings were exposed to light intensities comparable to those in which they were grown, their photosynthetic rates correlated with their dry matter production.When the CO2 concentration was raised to 1245 p.p.m., photosynthetic rates of leaves of sun- and shade-grown seedlings increased by the same relative amount. It is concluded that the poor adaptation of yellow birch to shade results from a reduction in content of carboxylating enzymes rather than changes in chlorophyll content or resistance to CO2 diffusion. Adaptations of yellow birch are contrasted with those of sugar maple (Acer saccharum Marsh.).

scholarly journals Small-Molecule Acetylation Controls the Degradation of Benzoate and Photosynthesis inRhodopseudomonas palustris

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Chelsey M. VanDrisse ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Rhodopseudomonas Palustris ◽  
Photosynthetic Apparatus ◽  
Reducing Power ◽  
Proton Motive Force ◽  
Motive Force ◽  
Light Harvesting Complexes ◽  
Pigment Synthesis ◽  
Content Type ◽  
Genes Encoding

ABSTRACTThe degradation of lignin-derived aromatic compounds such as benzoate has been extensively studied inRhodopseudomonas palustris, and the chemistry underpinning the conversion of benzoate to acetyl coenzyme A (acetyl-CoA) is well understood. Here we characterize the last unknown gene, badL,of thebad(benzoic acid degradation) cluster. BadL function is required for growth under photoheterotrophic conditions with benzoate as the organic carbon source (i.e., light plus anoxia). On the basis of bioinformatics andin vivoandin vitrodata, we show that BadL, aGcn5-relatedN-acetyltransferase (GNAT) (PF00583), acetylates aminobenzoates to yield acetamidobenzoates. The latter relieved repression of thebadDEFGABoperon by binding to BadM, triggering the synthesis of enzymes that activate and dearomatize the benzene ring. We also show that acetamidobenzoates are required for the expression of genes encoding the photosynthetic reaction center light-harvesting complexes through a BadM-independent mechanism. The effect of acetamidobenzoates on pigment synthesis is new and different than their effect on the catabolism of benzoate.IMPORTANCEThis work shows that the BadL protein ofRhodopseudomonas palustrishasN-acetyltransferase activity and that this activity is required for the catabolism of benzoate under photosynthetic conditions in this bacterium.R. palustrisoccupies lignin-rich habitats, making its benzoate-degrading capability critical for the recycling of this important, energy-rich biopolymer. This work identifies the product of the BadL enzyme as acetamidobenzoates, which were needed to derepress genes encoding benzoate-degrading enzymes and proteins of the photosynthetic apparatus responsible for the generation of the proton motive force under anoxia in the presence of light. In short, acetamidobenzoates potentially coordinate the use of benzoate as a source of reducing power and carbon with the generation of a light-driven proton motive force that fuels ATP synthesis, motility, transport, and many other processes in the metabolically versatile bacteriumR. palustris.

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