Photosynthesis in the Aquatic Macrophyte Egeria densa. II. Effects of Inorganic Carbon Conditions on 14C Fixation

1979 ◽  
Vol 6 (1) ◽  
pp. 1 ◽  
Author(s):  
JA Browse ◽  
JMA Brown ◽  
FI Dromgoole
Keyword(s):  
Inorganic Carbon ◽  
Carbon Fixation ◽  
Aquatic Macrophyte ◽  
Calvin Cycle ◽  
Total Carbon ◽  
Absolute Amount ◽  
Ambient Conditions ◽  
Fixation Rate ◽  
Rate Of Photosynthesis ◽  
Time Courses

In short-term labelling experiments, tripling the concentration of total inorganic carbon (TIC) did not significantly increase the high rates of 14C fixation reported in an earlier paper [19.0 μmol C (g dry wt)-1 min-1 at pH 6.8, [TIC] = 1 mM]. However, either decreasing [TIC] or increasing the pH caused the fixation rate to fall markedly. Thus at pH 6.8, [TIC] = 38 μM and pH 10.2, [TIC] = 1.0 mM, photosynthesis was 2.3 and 1.3 μmol g-1 min-1, respectively. Time courses of the distribution of photosynthetic intermediates indicated that the Calvin cycle remained the predominant pathway of carbon fixation, irrespective of the ambient conditions of TIC and pH. When the rate of photosynthesis was reduced by decreasing [TIC] or increasing pH, the proportion (but not the absolute amount) of label found in malate increased. At pH 6.8, [TIC] = 2.9 mM, μ-carboxylation accounted for only 2.7% of the total carbon fixed, compared with 9% at air levels of CO2 (pH 4.5, [TIC] = 13 μM). Egeria does not appear to exhibit C4 photosynthesis under any of the conditions studied, but malate may be a significant product of photosynthesis whenever the fixation rate is reduced by carbon availability.

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 Stable Carbon Isotopic Fractionations Associated with Inorganic Carbon Fixation by Anaerobic Ammonium-Oxidizing Bacteria

2004 ◽  
Vol 70 (6) ◽  
pp. 3785-3788 ◽  
Author(s):  
Stefan Schouten ◽  
Marc Strous ◽  
Marcel M. M. Kuypers ◽  
W. Irene C. Rijpstra ◽  
Marianne Baas ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Carbon Fixation ◽  
Calvin Cycle ◽  
The Black Sea ◽  
Anammox Bacteria ◽  
Anammox Bacterium ◽  
Stable Carbon ◽  
Acetyl Coenzyme A ◽  
Carbon Isotopic ◽  
Isotopic Analyses

ABSTRACT Isotopic analyses of Candidatus “Brocadia anammoxidans,” a chemolithoautotrophic bacterium that anaerobically oxidizes ammonium (anammox), show that it strongly fractionates against 13C; i.e., lipids are depleted by up to 47‰ versus CO2. Similar results were obtained for the anammox bacterium Candidatus “Scalindua sorokinii,” which thrives in the anoxic water column of the Black Sea, suggesting that different anammox bacteria use identical carbon fixation pathways, which may be either the Calvin cycle or the acetyl coenzyme A pathway.

Evidence for bicarbonate accumulation by Anacystis nidulans

1984 ◽  
Vol 62 (7) ◽  
pp. 1398-1403 ◽  
Author(s):  
Barry J. Shelp ◽  
David T. Canvin
Keyword(s):  
Inorganic Carbon ◽  
Carbon Fixation ◽  
External Medium ◽  
Anacystis Nidulans ◽  
Carbon Pool ◽  
Carbon Accumulation ◽  
Total Carbon ◽  
Apparent Affinity ◽  
Photosynthetic Carbon Fixation ◽  
Photosynthetic Carbon

Kinetic studies of photosynthetic O2 evolution as a function of pH were conducted to investigate the nature of the inorganic carbon used during photosynthesis by Anacystis nidulans. At pH 5, the apparent affinity for carbon during photosynthesis was similar in air-grown and high CO2 grown cells, but at alkaline pH, the apparent affinity was much greater in air-grown cells. The substrate concentration for half-maximum rates of photosynthesis in air-grown cells remained constant as a function of pH when the substrate was expressed as total carbon, suggesting that these cells were capable of using varying proportions of CO2 and [Formula: see text]. Photosynthesis in high CO2 grown algae appeared to be more dependent on CO2 over the pH range, indicating that CO2 was the predominant carbon species used, but [Formula: see text] uptake was also indicated. Internal inorganic carbon and photosynthetic carbon fixation in air-grown cells were determined at pH 8.5, using silicone oil centrifugation. Anacystis accumulated inorganic carbon in large excess of that in the external medium by a mechanism which is sensitive to inhibitors of energy metabolism and independent of concurrent carbon fixation; light was required to accumulate and maintain the internal carbon pool. The degree of accumulation was a function of the carbon concentration in the external medium; at 12 μM external carbon, the accumulation ratio was in excess of 100-fold, whereas at 4.76 mM, the ratio was only 5-fold. The rates of carbon transport were always sufficient to maintain photosynthesis. Carbon efflux rates approaching 40% of the influx rate were found at equilibrium internal carbon concentrations. Kinetic parameters of photosynthesis are discussed with reference to the known properties of algal ribulose bisphosphate (RuBP) carboxylase–oxygenase. It is concluded that the internal inorganic carbon pool serves as an intermediate for photosynthetic carbon fixation and that, if CO2 and [Formula: see text] are in equilibrium, the carbon accumulation at ambient CO2 and O2 is sufficient to suppress RuBP oxygenase activity.

scholarly journals Nutrients recycle and the growth of Scenedesmus obliquus in synthetic wastewater under different sodium carbonate concentrations

2020 ◽  
Vol 7 (1) ◽  
pp. 191214 ◽  
Author(s):  
Yun Duan ◽  
Xin Guo ◽  
Jingjing Yang ◽  
Mingmei Zhang ◽  
Yangyang Li
Keyword(s):  
Sodium Carbonate ◽  
Inorganic Carbon ◽  
Carbon Fixation ◽  
Dissolved Inorganic Carbon ◽  
Scenedesmus Obliquus ◽  
Biomass Accumulation ◽  
Synthetic Wastewater ◽  
Nitrogen And Phosphorus ◽  
Fixation Rate ◽  
High Concentrations

This study illustrated the growth of Scenedesmus obliquus and recycle of nutrients in wastewater combined with inorganic carbon under autotrophic conditions. Scenedesmus obliquus was cultivated under different conditions by adding sodium carbonate (Na 2 CO 3 ) at 15–40 mg l −1 separately in wastewater containing high nitrogen and phosphorus content. The growth characteristics of S. obliquus , pH and dissolved inorganic carbon (DIC) changes of microalgae liquid, the recycle rate of ammonia and phosphorus and lipid content were determined. The changes of pH and DIC showed that S. obliquus could use Na 2 CO 3 to grow, with lipid contents of 18–25%. Among all Na 2 CO 3 concentrations, 20 mg l −1 was the optimum, of which S. obliquus had the highest NH 3 -N recycle of 52% and P O 4 3 – P recycle of 67%. By the 14th day, its biomass production also reaches the maximum of 0.21 g l −1 . However, inorganic carbon fixation rate was inversely proportional to its concentration. Moreover, the biomass was in positive correlation with the Na 2 CO 3 concentration except 20 mg l −1 , which provided a possibility that S. obliquus could be acclimatized to adjust to high concentrations of inorganic carbon to promote biomass accumulation and recycle of nutrients.

Bicarbonate uptake rates and diversity of RuBisCO genes in saline lake sediments

2021 ◽  
Vol 97 (4) ◽  
Author(s):  
Beichen Wang ◽  
Jianrong Huang ◽  
Jian Yang ◽  
Hongchen Jiang ◽  
Haiyi Xiao ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Carbon Fixation ◽  
Dissolved Inorganic Carbon ◽  
Full Range ◽  
Microbial Populations ◽  
Fixation Rate ◽  
Organic Carbon Concentration ◽  
Uptake Rates ◽  
Bicarbonate Uptake ◽  
And Function

ABSTRACT There is limited knowledge of microbial carbon fixation rate, and carbon-fixing microbial abundance and diversity in saline lakes. In this study, the inorganic carbon uptake rates and carbon-fixing microbial populations were investigated in the surface sediments of lakes with a full range of salinity from freshwater to salt saturation. The results showed that in the studied lakes light-dependent bicarbonate uptake contributed substantially (>70%) to total bicarbonate uptake, while the contribution of dark bicarbonate uptake (1.35–25.17%) cannot be ignored. The light-dependent bicarbonate uptake rates were significantly correlated with pH and turbidity, while dark bicarbonate uptake rates were significantly influenced by dissolved inorganic carbon, pH, temperature and salinity. Carbon-fixing microbial populations using the Calvin-Benson-Bassham pathway were widespread in the studied lakes, and they were dominated by the cbbL and cbbM gene types affiliated with Cyanobacteria and Proteobacteria, respectively. The cbbL and cbbM gene abundance and population structures were significantly affected by different environmental variables, with the cbbL and cbbM genes being negatively correlated with salinity and organic carbon concentration, respectively. In summary, this study improves our knowledge of the abundance, diversity and function of carbon-fixing microbial populations in the lakes with a full range of salinity.

scholarly journals Time-coursed transcriptome analysis identifies key expressional regulation in growth cessation and dormancy induced by short days in Paulownia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jiayuan Wang ◽  
Hongyan Wang ◽  
Tao Deng ◽  
Zhen Liu ◽  
Xuewen Wang
Keyword(s):  
Molecular Mechanisms ◽  
Carbon Fixation ◽  
De Novo ◽  
Regulation Of Gene Expression ◽  
Calvin Cycle ◽  
Rna Seq ◽  
Growth Cessation ◽  
Time Courses ◽  
Terminal Shoot ◽  
Coupling Point

Abstract Maintaining the viability of the apical shoot is critical for continued vertical growth in plants. Terminal shoot of tree species Paulownia cannot regrow in subsequent years. The short day (SD) treatment leads to apical growth cessation and dormancy. To understand the molecular basis of this, we further conducted global RNA-Seq based transcriptomic analysis in apical shoots to check regulation of gene expression. We obtained ~219 million paired-end 125-bp Illumina reads from five time-courses and de novo assembled them to yield 49,054 unigenes. Compared with the untreated control, we identified 1540 differentially expressed genes (DEGs) which were found to involve in 116 metabolic pathways. Expression of 87% of DEGs exhibited switch-on or switch-off pattern, indicating key roles in growth cessation. Most DEGs were enriched in the biological process of gene ontology categories and at later treatment stages. The pathways of auxin and circadian network were most affected and the expression of associated DEGs was characterised. During SD induction, auxin genes IAA, ARF and SAURs were down-regulated and circadian genes including PIF3 and PRR5 were up-regulated. PEPC in photosynthesis was constitutively upregulated, suggesting a still high CO2 concentrating activity; however, the converting CO2 to G3P in the Calvin cycle is low, supported by reduced expression of GAPDH encoding the catalysing enzyme for this step. This indicates a de-coupling point in the carbon fixation. The results help elucidate the molecular mechanisms for SD inducing dormancy and cessation in apical shoots.

Transport of soluble organic and inorganic carbon in sandy soils under nitrogen fertilization

1999 ◽  
Vol 79 (2) ◽  
pp. 303-310 ◽  
Author(s):  
F. L. Wang ◽  
A. K. Alva
Keyword(s):  
Nitrogen Fertilization ◽  
Inorganic Carbon ◽  
Average Rate ◽  
Sandy Soils ◽  
Water Soluble ◽  
Total Carbon ◽  
Total Carbon Content ◽  
Water Soluble Organic Carbon ◽  
Isobutylidene Diurea ◽  
Leaching Condition

Leaching of water soluble soil carbon plays an important role in downward transport of soil nutrients and pollutants and may be influenced by soil and management factors. We examined the leaching of water soluble carbon from two sandy soils under nitrogen fertilization by adapting an intermittent leaching-incubation technique using packed soil columns (94 × 10 cm). After 30 d, cumulative amounts of water-soluble organic carbon (SOC) leached from the Candler and Wabasso sand for various treatments in mg C column−1 were: 77 and 302 (NH4NO3), 64 and 265 (control), and 45 and 239 (isobutylidene diurea, IBDU), respectively. The IBDU and NH4NO3 treatments increased the leaching of water-soluble inorganic carbon (SIC), which ranged from 2 to 38 mg C column−1 over 30 d. At the end of eight cycles of leaching/incubation, the total carbon content increased at depth (control and NH4NO3 treatment) in the Candler sand, but decreased in the Wabasso sand. In the first leaching event, the average rate of SOC leaching from the Wabasso sand was 26 mg C column−1 d−1 which dropped rapidly to about 5 mg C column−1 d−1 towards the end of the experiment. The rate of SOC leaching from the Candler sand was much lower (<8 mg C column−1 d−1) than the rate of SOC leaching from the Wabasso sand. Compared with the unamended treatments, application of NH4NO3 increased and IBDU decreased the leaching of SOC in both soils. These effects of N application were considerable during the initial two to three leaching events only. Our results suggest that the initial rainfalls that follow a dry period may be critical for transporting SOC from the upper layer of these sandy soils. Key words: C leaching, sandy soil, intermittent leaching condition, isobutylidene

A simple dynamic model of photosynthesis in oak leaves: coupling leaf conductance and photosynthetic carbon fixation by a variable intracellular CO2 pool

2004 ◽  
Vol 31 (12) ◽  
pp. 1195 ◽  
Author(s):  
Steffen M. Noe ◽  
Christoph Giersch
Keyword(s):  
Carbon Fixation ◽  
Calvin Cycle ◽  
Target Function ◽  
Vapour Pressure Deficit ◽  
Co2 Assimilation ◽  
Leaf Conductance ◽  
Co2 Partial Pressure ◽  
Sink Term ◽  
Essential Components ◽  
Oak Leaves

Modelling the diurnal course of photosynthesis in oak leaves (Quercus robur L.) requires appropriate description of the dynamics of leaf photosynthesis of which diurnal variations in leaf conductance and in CO2 assimilation are essential components. We propose and analyse a simple photosynthesis model with three variables: leaf conductance (gs), the CO2 partial pressure inside the leaf (pi), and a pool of Calvin cycle intermediates (aps). The environmental factors light (I) and vapour pressure deficit (VPD) are used to formulate a target function G(I, VPD) from which the actual leaf conductance is calculated. Using this gs value and a CO2 consumption term representing CO2 fixation, a differential equation for pi is derived. Carboxylation corresponds to the sink term of the pi pool and is assumed to be feedback-inhibited by aps. This simple model is shown to produce reasonable to excellent fits to data on the diurnal time courses of photosythesis, pi and gs sampled for oak leaves.

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