scholarly journals Carbon Assimilation and Carbohydrate Metabolism of `Concord' Grape (Vitis labrusca L.) Leaves in Response to Nitrogen Supply

2003 ◽  
Vol 128 (5) ◽  
pp. 754-760 ◽  
Author(s):  
Li-Song Chen ◽  
Lailiang Cheng
Keyword(s):  
Calvin Cycle ◽  
Starch Degradation ◽  
Similar Response ◽  
Vitis Labrusca ◽  
Carbon Export ◽  
Bisphosphate Carboxylase ◽  
Key Enzymes ◽  
N Limitation ◽  
Wide Range ◽  
Leaf N

One-year-old grapevines (Vitis labrusca L. `Concord') were supplied twice weekly for 5 weeks with 0, 5, 10, 15, or 20 mm nitrogen (N) in a modified Hoagland's solution to generate a wide range of leaf N status. Both light-saturated CO2 assimilation at ambient CO2 and at saturating CO2 increased curvilinearly as leaf N increased. Although stomatal conductance showed a similar response to leaf N as CO2 assimilation, calculated intercellular CO2 concentrations decreased. On a leaf area basis, activities of key enzymes in the Calvin cycle, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoribulokinase (PRK), and key enzymes in sucrose and starch synthesis, fructose-1,6-bisphosphatase (FBPase), sucrose phosphate synthase (SPS), and ADP-glucose pyrophosphorylase (AGPase), increased linearly with increasing leaf N content. When expressed on a leaf N basis, activities of the Calvin cycle enzymes increased with increasing leaf N, whereas activities of FBPase, SPS, and AGPase did not show significant change. As leaf N increased, concentrations of glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), and 3-phosphoglycerate (PGA) increased curvilinearly. The ratio of G6P/F6P remained unchanged over the leaf N range except for a significant drop at the lowest leaf N. Concentrations of glucose, fructose, and sucrose at dusk increased linearly with increasing leaf N, and there was no difference between predawn and dusk measurements. As leaf N increased, starch concentration increased linearly at dusk, but decreased linearly at predawn. The calculated carbon export from starch degradation during the night increased with increasing leaf N. These results showed that 1) grapes leaves accumulated less soluble carbohydrates under N-limitation; 2) the elevated starch level in low N leaves at predawn was the result of the reduced carbon export from starch degradation during the night; and 3) the reduced capacity of CO2 assimilation in low N leaves was caused by the coordinated decreases in the activities of key enzymes involved in CO2 assimilation as a result of direct N limitation, not by the indirect feedback repression of CO2 assimilation via sugar accumulation.

scholarly journals CO2 Assimilation, Carbohydrate Metabolism, Xanthophyll Cycle, and the Antioxidant System of `Honeycrisp' Apple Leaves with Zonal Chlorosis

2004 ◽  
Vol 129 (5) ◽  
pp. 729-737 ◽  
Author(s):  
Li-Song Chen ◽  
Lailiang Cheng
Keyword(s):  
Excitation Energy ◽  
Carbohydrate Metabolism ◽  
Antioxidant System ◽  
Xanthophyll Cycle ◽  
Calvin Cycle ◽  
Thermal Dissipation ◽  
Nonstructural Carbohydrates ◽  
Bisphosphate Carboxylase ◽  
Key Enzymes ◽  
Fructose 1,6 Bisphosphatase

To determine the cause of a characteristic zonal chlorosis of `Honeycrisp' apple (Malus ×domestica Borkh.) leaves, we compared CO2 assimilation, carbohydrate metabolism, the xanthophyll cycle and the antioxidant system between chlorotic leaves and normal leaves. Chlorotic leaves accumulated higher levels of nonstructural carbohydrates, particularly starch, sorbitol, sucrose, and fructose at both dusk and predawn, and no difference was found in total nonstructural carbohydrates between predawn and dusk. This indicates that carbon export was inhibited in chlorotic leaves. CO2 assimilation and the key enzymes in the Calvin cycle, ribulose 1,5-bisphosphate carboxylase/oxygenase, NADP-glyceraldehyde-3-phosphate dehydrogenase, phosphoribulokinase, stromal fructose-1,6-bisphosphatase, and the key enzymes in starch and sorbitol synthesis, ADP-glucose pyrophosphorylase, cytosolic fructose-1,6-bisphosphatase, and aldose 6-phosphate reductase were significantly lower in chlorotic leaves than in normal leaves. However, sucrose phosphate synthase activity was higher in chlorotic leaves. In response to a reduced demand for photosynthetic electron transport, thermal dissipation of excitation energy (measured as nonphotochemical quenching of chlorophyll fluorescence) was enhanced in chlorotic leaves under full sun, lowering the efficiency of excitation energy transfer to PSII reaction centers. This was accompanied by a corresponding increase in both xanthophyll cycle pool size (on a chlorophyll basis) and conversion of violaxanthin to antheraxanthin and zeaxanthin. The antioxidant system, including superoxide dismutase and ascorbate peroxidase and the ascorbate pool and glutathione pool, was up-regulated in chlorotic leaves in response to the increased generation of reactive oxygen species via photoreduction of oxygen. These findings support the hypothesis that phloem loading and/or transport is partially or completely blocked in chlorotic leaves, and that excessive accumulation of nonstructural carbohydrates may cause feedback suppression of CO2 assimilation via direct interference with chloroplast function and/or indirect repression of photosynthetic enzymes.

scholarly journals Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) is essential for growth of the methanotroph Methylococcus capsulatus Bath.

2021 ◽  
Author(s):  
Calvin A. Henard ◽  
Chao Wu ◽  
Wei Xiong ◽  
Jessica M. Henard ◽  
Brett Davidheiser-Kroll ◽  
...  
Keyword(s):  
Gas Flow ◽  
Carbon Sources ◽  
Calvin Cycle ◽  
Pentose Phosphate ◽  
Methylococcus Capsulatus ◽  
Bisphosphate Carboxylase ◽  
Key Enzymes ◽  
C Isotopes ◽  
Genes Encoding ◽  
Assimilation Capacity

The ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) enzyme found in plants, algae, and an array of autotrophic bacteria is also encoded by a subset of methanotrophs, but its role in these microbes has largely remained elusive. In this study, we identified that CO 2 was requisite for RubisCO-encoding Methylococcus capsulatus Bath growth in a bioreactor with continuous influent and effluent gas flow. RNA sequencing identified active transcription of several carboxylating enzymes, including key enzymes of the Calvin and serine cycles, that could mediate CO 2 assimilation during cultivation with both CH 4 and CO 2 as carbon sources. Marker-exchange mutagenesis of M. capsulatus Bath genes encoding key enzymes of potential CO 2 -assimilating metabolic pathways indicated that a complete serine cycle is not required while RubisCO is essential for growth of this bacterium. 13 CO 2 tracer analysis showed that CH 4 and CO 2 enter overlapping anaplerotic pathways and implicated RubisCO as the primary enzyme mediating CO 2 assimilation in M. capsulatus Bath. Notably, we quantified the relative abundance of 3-phosphoglycerate and ribulose-1,5-bisphosphate 13 C isotopes, which supported that RubisCO-produced 3-phosphoglycerate is primarily converted to ribulose-1-5-bisphosphate via the oxidative pentose phosphate pathway in M. capsulatus Bath. Collectively, our data establish that RubisCO and CO 2 play essential roles in M. capsulatus Bath metabolism. This study expands the known capacity of methanotrophs to fix CO 2 via RubisCO, which may play a more pivotal role in the Earth’s biogeochemical carbon cycling and greenhouse gas regulation than previously recognized. Further, M. capsulatus Bath and other CO 2 -assimilating methanotrophs represent excellent candidates for use in the bioconversion of biogas waste streams that consist of both CH 4 and CO 2 . Importance The importance of RubisCO and CO 2 in M. capsulatus Bath metabolism is unclear. In this study, we demonstrated that both CO 2 and RubisCO are essential for M. capsulatus Bath growth. 13 CO 2 tracing experiments supported that RubisCO mediates CO 2 fixation and a non-canonical Calvin cycle is active in this organism. Our study provides insights into the expanding knowledge of methanotroph metabolism and implicates dual CH 4 /CO 2 -utilizing bacteria as more important players in the biogeochemical carbon cycle than previously appreciated. In addition, M. capsulatus and other methanotrophs with CO 2 assimilation capacity represent candidate organisms for the development of biotechnologies to mitigate the two most abundant greenhouse gases CH 4 and CO 2 .

Hepatoprotective Role of Berberine on Doxorubicin Induced Hepatotoxicity - Involvement of Cyp

2020 ◽  
Vol 21 (7) ◽  
pp. 541-547
Author(s):  
Bao Sun ◽  
Yue Yang ◽  
Mengzi He ◽  
Yanan Jin ◽  
Xiaoyu Cao ◽  
...  
Keyword(s):  
Drug Metabolism ◽  
Cardiac Tissue ◽  
Liver Toxicity ◽  
Elevated Serum ◽  
Similar Response ◽  
Wide Range ◽  
Cytokine Levels ◽  
Major Organ ◽  
Anti Oxidant

Background: The liver is one of the major organ involved in drug metabolism. Cytochrome P450s are predominantly involved in drug metabolism. A wide range of CYPs have been reported in the liver which have been involved in its normal as well as in diseased conditions. Doxorubicin, one of the most potent chemotherapeutic drugs, although highly efficacious, also has adverse side effects, with its targets being liver and cardiac tissue. Objective: The study aims to evaluate the reversal potentials of berberine on Doxorubicin induced cyp conversion. Methodology: In the present study, the interplay between anti-oxidants, cytochrome and inflammatory markers in DOX induced liver toxicity and its possible reversal by berberine was ascertained. Results: DOX administration significantly elevated serum as well as tissue stress, which was reverted by berberine treatment. A similar response was observed in tissue inflammatory mediators as well as in serum cytokine levels. Most profound reduction in the cytochrome expression was found in Cyp 2B1, 2B2, and 2E1. However, 2C1, 2C6, and 3A1 although showed a decline, but it did not revert the expression back to control levels. Conclusion: It could be concluded that berberine may be an efficient anti-oxidant and immune modulator. It possesses low to moderate cytochrome modulatory potentials.

Development and Validation of a New Scoring Tool to Evaluate the Clinical Evolution of Adult Patients with Nonsegmental Vitiligo

Dermatology ◽  
2021 ◽  
pp. 1-9
Author(s):  
María Luisa Peralta-Pedrero ◽  
Denisse Herrera-Bringas ◽  
Karla Samantha Torres-González ◽  
Martha Alejandra Morales-Sánchez ◽  
Fermín Jurado Santa-Cruz ◽  
...  
Keyword(s):  
Body Surface ◽  
Task Force ◽  
Intraclass Correlation ◽  
The Body ◽  
Response To Treatment ◽  
Similar Response ◽  
Clinical Evolution ◽  
Wide Range ◽  
Patient Reported ◽  
Extreme Groups

<b><i>Background:</i></b> Vitiligo has an unpredictable course and a variable response to treatment. Furthermore, the improvement of some vitiligo lesions cannot be considered a guarantee of a similar response to the other lesions. Instruments for patient-reported outcome measures (PROM) can be an alternative to measure complex constructions such as clinical evolution. <b><i>Objective:</i></b> The aim of this study was to validate a PROM that allows to measure the clinical evolution of patients with nonsegmental vitiligo in a simple but standardized way that serves to gather information for a better understanding of the disease. <b><i>Methods:</i></b> The instrument was created through expert consensus and patient participation. For the validation study, a prospective cohort design was performed. The body surface area affected was measured with the Vitiligo Extension Score (VES), the extension, the stage, and the spread by the evaluation of the Vitiligo European Task Force assessment (VETFa). Reliability was determined with test-retest, construct validity through hypothesis testing, discriminative capacity with extreme groups, and response capacity by comparing initial and final measurements. <b><i>Results:</i></b> Eighteen semi-structured interviews and 7 cognitive interviews were conducted, and 4 dermatologists were consulted. The instrument Clinical Evolution-Vitiligo (CV-6) was answered by 119 patients with a minimum of primary schooling. A wide range was observed in the affected body surface; incident and prevalent cases were included. The average time to answer the CV-6 was 3.08 ± 0.58 min. In the test-retest (<i>n</i> = 53), an intraclass correlation coefficient was obtained: 0.896 (95% CI 0.82–0.94; <i>p</i> &#x3c; 0.001). In extreme groups, the mean score was 2 (2–3) and 5 (4–6); <i>p</i> &#x3c; 0.001. The initial CV-6 score was different from the final one and the change was verified with VES and VETFa (<i>p</i> &#x3c; 0.05, <i>n</i> = 92). <b><i>Conclusions:</i></b> The CV-6 instrument allows patient collaboration, it is simple and brief, and it makes it easier for the doctor to focus attention on injuries that present changes at the time of medical consultation.

scholarly journals Genome analysis of Pseudomonas sp. OF001 and Rubrivivax sp. A210 suggests multicopper oxidases catalyze manganese oxidation required for cylindrospermopsin transformation

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Erika Berenice Martínez-Ruiz ◽  
Myriel Cooper ◽  
Jimena Barrero-Canosa ◽  
Mindia A. S. Haryono ◽  
Irina Bessarab ◽  
...  
Keyword(s):  
Calvin Cycle ◽  
Multicopper Oxidase ◽  
Genomic Islands ◽  
Biotechnological Applications ◽  
High Similarity ◽  
Multicopper Oxidases ◽  
Metabolic Potential ◽  
Natural Habitats ◽  
Manganese Oxidation ◽  
Wide Range

Abstract Background Cylindrospermopsin is a highly persistent cyanobacterial secondary metabolite toxic to humans and other living organisms. Strain OF001 and A210 are manganese-oxidizing bacteria (MOB) able to transform cylindrospermopsin during the oxidation of Mn2+. So far, the enzymes involved in manganese oxidation in strain OF001 and A210 are unknown. Therefore, we analyze the genomes of two cylindrospermopsin-transforming MOB, Pseudomonas sp. OF001 and Rubrivivax sp. A210, to identify enzymes that could catalyze the oxidation of Mn2+. We also investigated specific metabolic features related to pollutant degradation and explored the metabolic potential of these two MOB with respect to the role they may play in biotechnological applications and/or in the environment. Results Strain OF001 encodes two multicopper oxidases and one haem peroxidase potentially involved in Mn2+ oxidation, with a high similarity to manganese-oxidizing enzymes described for Pseudomonas putida GB-1 (80, 83 and 42% respectively). Strain A210 encodes one multicopper oxidase potentially involved in Mn2+ oxidation, with a high similarity (59%) to the manganese-oxidizing multicopper oxidase in Leptothrix discophora SS-1. Strain OF001 and A210 have genes that might confer them the ability to remove aromatic compounds via the catechol meta- and ortho-cleavage pathway, respectively. Based on the genomic content, both strains may grow over a wide range of O2 concentrations, including microaerophilic conditions, fix nitrogen, and reduce nitrate and sulfate in an assimilatory fashion. Moreover, the strain A210 encodes genes which may convey the ability to reduce nitrate in a dissimilatory manner, and fix carbon via the Calvin cycle. Both MOB encode CRISPR-Cas systems, several predicted genomic islands, and phage proteins, which likely contribute to their genome plasticity. Conclusions The genomes of Pseudomonas sp. OF001 and Rubrivivax sp. A210 encode sequences with high similarity to already described MCOs which may catalyze manganese oxidation required for cylindrospermopsin transformation. Furthermore, the analysis of the general metabolism of two MOB strains may contribute to a better understanding of the niches of cylindrospermopsin-removing MOB in natural habitats and their implementation in biotechnological applications to treat water.

scholarly journals Design and in vitro realization of carbon-conserving photorespiration

2018 ◽  
Vol 115 (49) ◽  
pp. E11455-E11464 ◽  
Author(s):  
Devin L. Trudeau ◽  
Christian Edlich-Muth ◽  
Jan Zarzycki ◽  
Marieke Scheffen ◽  
Moshe Goldsmith ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Calvin Cycle ◽  
Computational Design ◽  
Carbon Loss ◽  
Fixation Rate ◽  
Bisphosphate Carboxylase ◽  
Stoichiometric Model ◽  
Synthetic Routes ◽  
Coa Reductase

Photorespiration recycles ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) oxygenation product, 2-phosphoglycolate, back into the Calvin Cycle. Natural photorespiration, however, limits agricultural productivity by dissipating energy and releasing CO2. Several photorespiration bypasses have been previously suggested but were limited to existing enzymes and pathways that release CO2. Here, we harness the power of enzyme and metabolic engineering to establish synthetic routes that bypass photorespiration without CO2 release. By defining specific reaction rules, we systematically identified promising routes that assimilate 2-phosphoglycolate into the Calvin Cycle without carbon loss. We further developed a kinetic–stoichiometric model that indicates that the identified synthetic shunts could potentially enhance carbon fixation rate across the physiological range of irradiation and CO2, even if most of their enzymes operate at a tenth of Rubisco’s maximal carboxylation activity. Glycolate reduction to glycolaldehyde is essential for several of the synthetic shunts but is not known to occur naturally. We, therefore, used computational design and directed evolution to establish this activity in two sequential reactions. An acetyl-CoA synthetase was engineered for higher stability and glycolyl-CoA synthesis. A propionyl-CoA reductase was engineered for higher selectivity for glycolyl-CoA and for use of NADPH over NAD+, thereby favoring reduction over oxidation. The engineered glycolate reduction module was then combined with downstream condensation and assimilation of glycolaldehyde to ribulose 1,5-bisphosphate, thus providing proof of principle for a carbon-conserving photorespiration pathway.

scholarly journals CO2 Assimilation, Photosynthetic Enzymes, and Carbohydrates of `Concord' Grape Leaves in Response to Iron Supply

2004 ◽  
Vol 129 (5) ◽  
pp. 738-744 ◽  
Author(s):  
Li-Song Chen ◽  
Brandon R. Smith ◽  
Lailiang Cheng
Keyword(s):  
Sucrose Concentration ◽  
Calvin Cycle ◽  
Sucrose Phosphate Synthase ◽  
Nonstructural Carbohydrates ◽  
Bisphosphate Carboxylase ◽  
Chl A ◽  
Photosynthetic Enzymes ◽  
Fe Content ◽  
Significant Difference ◽  
Assimilation Capacity

Own-rooted 1-year-old `Concord' grapevines (Vitis labruscana Bailey) were fertigated twice weekly for 11 weeks with 1, 10, 20, 50, or 100 μm iron (Fe) from ferric ethylenediamine di (o-hydroxyphenylacetic) acid (Fe-EDDHA) in a complete nutrient solution. As Fe supply increased, leaf total Fe content did not show a significant change, whereas active Fe (extracted by 2,2′-dipyridyl) content increased curvilinearly. Chlorophyll (Chl) content increased as Fe supply increased, with a greater response at the lower Fe rates. Chl a: b ratio remained relatively constant over the range of Fe supply, except for a slight increase at the lowest Fe treatment. Both CO2 assimilation and stomatal conductance increased curvilinearly with increasing leaf active Fe, whereas intercellular CO2 concentrations decreased linearly. Activities of key enzymes in the Calvin cycle, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoribulokinase (PRK), stromal fructose-1,6-bisphosphatase (FBPase), and a key enzyme in sucrose synthesis, cytosolic FBPase, all increased linearly with increasing leaf active Fe. No significant difference was found in the activities of ADP-glucose pyrophosphorylase (AGPase) and sucrose phosphate synthase (SPS) of leaves between the lowest and the highest Fe treatments, whereas slightly lower activities of AGPase and SPS were observed in the other three Fe treatments. Content of 3-phosphoglycerate (PGA) increased curvilinearly with increasing leaf active Fe, whereas glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), and the ratio of G6P: F6P remained unchanged over the range of Fe supply. Concentrations of glucose, fructose, sucrose, starch, and total nonstructural carbohydrates (TNC) at both dusk and predawn increased with increasing leaf active Fe. Concentrations of starch and TNC at any given leaf active Fe content were higher at dusk than at predawn, but both glucose and fructose showed the opposite trend. No difference in sucrose concentration was found at dusk or predawn. The export of carbon from starch breakdown during the night, calculated as the difference between dusk and predawn measurements, increased as leaf active Fe content increased. The ratio of starch to sucrose at both dusk and predawn also increased with increasing leaf active Fe. In conclusion, Fe limitation reduces the activities of Rubisco and other photosynthetic enzymes, and hence CO2 assimilation capacity. Fe-deficient grapevines have lower concentrations of nonstructural carbohydrates in source leaves and, therefore, are source limited.

scholarly journals Evolved phenological cueing strategies show variable responses to climate change

2018 ◽  
Author(s):  
Collin B. Edwards ◽  
Louie Yang
Keyword(s):  
Climate Change ◽  
Climatic Conditions ◽  
Similar Response ◽  
Climate Data ◽  
Global Pattern ◽  
Continental Scale ◽  
Fitness Consequences ◽  
Wide Range ◽  
Correlation Structures ◽  
Phenological Shifts

AbstractSeveral studies have documented a global pattern of phenological advancement that is consistent with ongoing climate change. However, the magnitude of these phenological shifts is highly variable across taxa and locations. This variability of phenological responses has been difficult to explain mechanistically. To examine how the evolution of multi-trait cueing strategies could produce variable responses to climate change, we constructed a model in which organisms evolve strategies that integrate multiple environmental cues to inform anticipatory phenological decisions. We simulated the evolution of phenological cueing strategies in multiple environments, using historic climate data from 78 locations in North America and Hawaii to capture features of climatic correlation structures in the real world. Organisms in our model evolved diverse strategies that were spatially autocorrelated across locations on a continental scale, showing that similar strategies tend to evolve in similar climates. Within locations, organisms often evolved a wide range of strategies that showed similar response phenotypes and fitness outcomes under historical conditions. However, these strategies responded differently to novel climatic conditions, with variable fitness consequences. Our model shows how the evolution of phenological cueing strategies can explain observed variation in phenological shifts and unexpected responses to climate change.

scholarly journals Genome- and Community-Level Interaction Insights into Carbon Utilization and Element Cycling Functions of Hydrothermarchaeota in Hydrothermal Sediment

mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Zhichao Zhou ◽  
Yang Liu ◽  
Wei Xu ◽  
Jie Pan ◽  
Zhu-Hua Luo ◽  
...  
Keyword(s):  
Community Level ◽  
Data Sets ◽  
Carbon Utilization ◽  
Black Smoker ◽  
Community Interactions ◽  
Element Cycling ◽  
Bisphosphate Carboxylase ◽  
Hydrothermal Sediment ◽  
Wide Range ◽  
Functional Components

ABSTRACT Hydrothermal vents release reduced compounds and small organic carbon compounds into the surrounding seawater, providing essential substrates for microbial growth and bioenergy transformations. Despite the wide distribution of the marine benthic group E archaea (referred to as Hydrothermarchaeota) in the hydrothermal environment, little is known about their genomic repertoires and biogeochemical significance. Here, we studied four highly complete (>80%) metagenome-assembled genomes (MAGs) from a black smoker chimney and the surrounding sulfur-rich sediments on the South Atlantic Mid-Ocean Ridge and publicly available data sets (the Integrated Microbial Genomes system of the U.S. Department of Energy-Joint Genome Institute and NCBI SRA data sets). Genomic analysis suggested a wide carbon metabolic diversity of Hydrothermarchaeota members, including the utilization of proteins, lactate, and acetate; the anaerobic degradation of aromatics; the oxidation of C1 compounds (CO, formate, and formaldehyde); the utilization of methyl compounds; CO2 incorporation by the tetrahydromethanopterin-based Wood-Ljungdahl pathway; and participation in the type III ribulose-1,5-bisphosphate carboxylase/oxygenase-based Calvin-Benson-Bassham cycle. These microbes also potentially oxidize sulfur, arsenic, and hydrogen and engage in anaerobic respiration based on sulfate reduction and denitrification. Among the 140 MAGs reconstructed from the black smoker chimney microbial community (including Hydrothermarchaeota MAGs), community-level metabolic predictions suggested a redundancy of carbon utilization and element cycling functions and interactive syntrophic and sequential utilization of substrates. These processes might make various carbon and energy sources widely accessible to the microorganisms. Further, the analysis suggested that Hydrothermarchaeota members contained important functional components obtained from the community via lateral gene transfer, becoming a distinctive clade. This might serve as a niche-adaptive strategy for metabolizing heavy metals, C1 compounds, and reduced sulfur compounds. Collectively, the analysis provides comprehensive metabolic insights into the Hydrothermarchaeota. IMPORTANCE This study provides comprehensive metabolic insights into the Hydrothermarchaeota from comparative genomics, evolution, and community-level perspectives. Members of the Hydrothermarchaeota synergistically participate in a wide range of carbon-utilizing and element cycling processes with other microorganisms in the community. We expand the current understanding of community interactions within the hydrothermal sediment and chimney, suggesting that microbial interactions based on sequential substrate metabolism are essential to nutrient and element cycling.

Inhibitory Action of Glufosinate on Photosynthesis

1993 ◽  
Vol 48 (3-4) ◽  
pp. 369-373 ◽  
Author(s):  
Aloysius Wild ◽  
Christine Wendler
Keyword(s):  
Enzyme Activity ◽  
Calvin Cycle ◽  
Atmospheric Conditions ◽  
Direct Inhibition ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Transamination Reaction ◽  
Ribulosebisphosphate Carboxylase ◽  
High Concentrations ◽  
Respiratory Conditions

Glufosinate (phosphinothricin) irreversibly blocks the glutamine synthetase which subsequently gives rise to an accumulation of ammonium and to a strong decrease in some amino acids, especially glutamine and glutamate.Under atmospheric conditions (400 ppm CO2, 21% O2) glufosinate causes a rapid inhibition of photosynthesis, too. H ow ever, under non-photo respiratory conditions (1000 ppm CO2, 2% O2) only a slight inhibition of photosynthesis occurs with glufosinate. Since under both conditions an accumulation of ammonium occurs, it is concluded that inhibition of photosynthesis is not induced by the higher concentrations of ammonium. The results rather suggest that the absence of amino donors in the glycolate pathway leads to a break-down of the transamination reaction of glyoxylate to glycine. This causes an inhibition of photorespiration and as a further consequence the inhibition of photosynthesis. There are two hypotheses for explaining this phenomenon. One of them supposes that the blockade in the glycolate pathway produces a lack of Calvin cycle intermediates which subsequently is the cause of the inhibition of photo synthesis. The other one suggests a direct inhibition of the ribulose-1,5-bisphosphate carboxylase by the accumulation of glyoxylate and P-glycolate.After treatment with different intermediates of the Calvin cycle and photorespiration to gether with glufosinate no decrease in the inhibition of photosynthesis could be measured. This suggests that the inhibition of photosynthesis is not induced by a depletion of intermediates of the Calvin cycle.Tests on the effect of glyoxylate and P-glycolate on ribulosebisphosphate carboxylase activity showed that in crude leaves extracts the enzyme activity can only be inhibited by high concentrations of these substances. However, in intact spinach chloroplasts the enzyme activity can be blocked by using much lower concentrations of glyoxylate. This may indicate that the ribulosebisphosphate carboxylase activase is affected by this metabolite and that this may be the reason for an inhibition of photosynthesis after treatment with glufosinate.

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