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Shi H, Ernst E, Heinzel N, McCorkle S, Rolletschek H, Borisjuk L, Ortleb S, Martienssen R, Shanklin J, Schwender J. Mechanisms of metabolic adaptation in the duckweed Lemna gibba: an integrated metabolic, transcriptomic and flux analysis. BMC PLANT BIOLOGY 2023; 23:458. [PMID: 37789269 PMCID: PMC10546790 DOI: 10.1186/s12870-023-04480-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 09/20/2023] [Indexed: 10/05/2023]
Abstract
BACKGROUND Duckweeds are small, rapidly growing aquatic flowering plants. Due to their ability for biomass production at high rates they represent promising candidates for biofuel feedstocks. Duckweeds are also excellent model organisms because they can be maintained in well-defined liquid media, usually reproduce asexually, and because genomic resources are becoming increasingly available. To demonstrate the utility of duckweed for integrated metabolic studies, we examined the metabolic adaptation of growing Lemna gibba cultures to different nutritional conditions. RESULTS To establish a framework for quantitative metabolic research in duckweeds we derived a central carbon metabolism network model of Lemna gibba based on its draft genome. Lemna gibba fronds were grown with nitrate or glutamine as nitrogen source. The two conditions were compared by quantification of growth kinetics, metabolite levels, transcript abundance, as well as by 13C-metabolic flux analysis. While growing with glutamine, the fronds grew 1.4 times faster and accumulated more protein and less cell wall components compared to plants grown on nitrate. Characterization of photomixotrophic growth by 13C-metabolic flux analysis showed that, under both metabolic growth conditions, the Calvin-Benson-Bassham cycle and the oxidative pentose-phosphate pathway are highly active, creating a futile cycle with net ATP consumption. Depending on the nitrogen source, substantial reorganization of fluxes around the tricarboxylic acid cycle took place, leading to differential formation of the biosynthetic precursors of the Asp and Gln families of proteinogenic amino acids. Despite the substantial reorganization of fluxes around the tricarboxylic acid cycle, flux changes could largely not be associated with changes in transcripts. CONCLUSIONS Through integrated analysis of growth rate, biomass composition, metabolite levels, and metabolic flux, we show that Lemna gibba is an excellent system for quantitative metabolic studies in plants. Our study showed that Lemna gibba adjusts to different nitrogen sources by reorganizing central metabolism. The observed disconnect between gene expression regulation and metabolism underscores the importance of metabolic flux analysis as a tool in such studies.
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Affiliation(s)
- Hai Shi
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Evan Ernst
- Cold Spring Harbor Laboratory, 1 Bungtown Rd, Cold Spring Harbor, NY, 11724, USA
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY, 11724, USA
| | - Nicolas Heinzel
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466, Seeland OT Gatersleben, Germany
| | - Sean McCorkle
- Brookhaven National Laboratory, Computational Science Initiative, Upton, NY, 11973, USA
| | - Hardy Rolletschek
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466, Seeland OT Gatersleben, Germany
| | - Ljudmilla Borisjuk
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466, Seeland OT Gatersleben, Germany
| | - Stefan Ortleb
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466, Seeland OT Gatersleben, Germany
| | - Robert Martienssen
- Cold Spring Harbor Laboratory, 1 Bungtown Rd, Cold Spring Harbor, NY, 11724, USA
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY, 11724, USA
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Jorg Schwender
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
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Ziegler P, Appenroth KJ, Sree KS. Survival Strategies of Duckweeds, the World's Smallest Angiosperms. PLANTS (BASEL, SWITZERLAND) 2023; 12:plants12112215. [PMID: 37299193 DOI: 10.3390/plants12112215] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/26/2023] [Accepted: 05/31/2023] [Indexed: 06/12/2023]
Abstract
Duckweeds (Lemnaceae) are small, simply constructed aquatic higher plants that grow on or just below the surface of quiet waters. They consist primarily of leaf-like assimilatory organs, or fronds, that reproduce mainly by vegetative replication. Despite their diminutive size and inornate habit, duckweeds have been able to colonize and maintain themselves in almost all of the world's climate zones. They are thereby subject to multiple adverse influences during the growing season, such as high temperatures, extremes of light intensity and pH, nutrient shortage, damage by microorganisms and herbivores, the presence of harmful substances in the water, and competition from other aquatic plants, and they must also be able to withstand winter cold and drought that can be lethal to the fronds. This review discusses the means by which duckweeds come to grips with these adverse influences to ensure their survival. Important duckweed attributes in this regard are a pronounced potential for rapid growth and frond replication, a juvenile developmental status facilitating adventitious organ formation, and clonal diversity. Duckweeds have specific features at their disposal for coping with particular environmental difficulties and can also cooperate with other organisms of their surroundings to improve their survival chances.
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Affiliation(s)
- Paul Ziegler
- Department of Plant Physiology, University of Bayreuth, 95440 Bayreuth, Germany
| | - Klaus J Appenroth
- Matthias Schleiden Institute-Plant Physiology, University of Jena, 07743 Jena, Germany
| | - K Sowjanya Sree
- Department of Environmental Science, Central University of Kerala, Periye 671320, India
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Komor E, Cho BH, Kraus M. The Occurrence of the Glucose-inducible Transport Systems for Glucose, Proline, and Arginine in Different Species ofChlorella. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/j.1438-8677.1988.tb00051.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Soh L, Connors KA, Brooks BW, Zimmerman J. Fate of sucralose through environmental and water treatment processes and impact on plant indicator species. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:1363-9. [PMID: 21235203 DOI: 10.1021/es102719d] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The degradation and partitioning of sucralose during exposure to a variety of environmental and advanced treatment processes (ATP) and the effect of sucralose on indicator plant species were systematically assessed. Bench scale experiments were used to reproduce conditions from environmental processes (microbial degradation, hydrolysis, soil sorption) and ATPs (chlorination, ozonation, sorption to activated carbon, and UV radiation). Degradation only occurred to a limited extent during hydrolysis, ozonation, and microbial processes indicating that breakdown of sucralose will likely be slow and incomplete leading to accumulation in surface waters. Further, the persistence of sucralose was compared to suggested human tracer compounds, caffeine and acesulfame-K. In comparison sucralose exhibits similar or enhanced characteristics pertaining to persistence, prevalence, and facile detection and can therefore be considered an ideal tracer for anthropogenic activity. Ecological effects of sucralose were assessed by measuring sucrose uptake inhibition in plant cotelydons and aquatic plant growth impairment. Sucralose did not inhibit plant cotelydon sucrose uptake, nor did it effect frond number, wet weight, or growth rate in aquatic plant, Lemna gibba. Though sucralose does not appear toxic to plant growth, the peristent qualities of sucralose may lead to chronic low-dose exposure with largely unknown consequences for human and environmental health.
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Affiliation(s)
- Lindsay Soh
- Environmental Engineering Program and ‡School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA
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Fischer-Schliebs E, Ball E, Berndt E, Besemfelder-Butz E, Binzel ML, Drobny M, Mühlenhoff D, Müller ML, Rakowski K, Ratajczak R. Differential immunological cross-reactions with antisera against the V-ATPase of Kalanchoë daigremontiana reveal structural differences of V-ATPase subunits of different plant species. Biol Chem 1997; 378:1131-9. [PMID: 9372182 DOI: 10.1515/bchm.1997.378.10.1131] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Two antisera (ATP88 and ATP95) raised against the V-ATPase holoenzyme of Kalanchoë daigremontiana were tested for their cross-reactivity with subunits of V-ATPases from other plant species. V-ATPases from Kalanchoë blossfeldiana, Mesembryanthemum crystallinum, Nicotiana tabacum, Lycopersicon esculentum, Citrus limon, Lemna gibba, Hordeum vulgare and Zea mays were immunoprecipitated with an antiserum against the catalytic V-ATPase subunit A of M. crystallinum. As shown by silver staining and Western blot analysis with ATP88, subunits A, B, C, D and c were present in all immunoprecipitated V-ATPases. In contrast, ATP95 recognized the whole set of subunits only in K. blossfeldiana, M. crystallinum, H. vulgare and Z. mays. This differential cross reactivity of ATP95 indicates the presence of structural differences of certain V-ATPase subunits. Based on the Bafilomycin A1-sensitive ATPase activity of tonoplast enriched vesicles, and on the amount of V-ATPase solubilized and immunoprecipitated, the specific ATP-hydrolysis activity of the V-ATPases under test was determined. The structural differences correlate with the ability of V-ATPases from different species to hydrolyze ATP at one given assay condition for ATP-hydrolysis measurements. Interestingly V-ATPases showing cross-reactivity of subunits A, B, C, D and c with ATP95 showed higher rates of specific ATP hydrolysis compared to V-ATPases containing subunits which were not labeled by ATP95. Thus, V-ATPases with high turnover rates in our assay conditions may show common structural characteristics which separate them from ATPases with low turnover rates.
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Bouteau F, Lacrotte R, Cornel D, Monestiez M, Bousquet U, Pennarun A, Rona J. Electrogenic active proton pump in Hevea brasiliensis laticiferous cells. J Electroanal Chem (Lausanne) 1991. [DOI: 10.1016/0022-0728(91)85598-j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Komor E, Cho BH, Schricker S, Schobert C. Charge and acidity compensation during proton-sugar symport in Chlorella: The H(+)-ATPase does not fully compensate for the sugar-coupled proton influx. PLANTA 1989; 177:9-17. [PMID: 24212267 DOI: 10.1007/bf00392149] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/1988] [Accepted: 09/09/1988] [Indexed: 06/02/2023]
Abstract
This study was undertaken in order to demonstrate the extent to which the activity of the plasmalemma H(+)-ATPase compensates for the charge and acidity flow caused by the sugar-proton symport in cells of chlorella vulgaris Beij.. Detailed analysis of H(+) and K(+) fluxes from and into the medium together with measurements of respiration, cytoplasmic pH, and cellular ATP-levels indicate three consecutive phases after the onset of H(+) symport. Phase 1 occurred immediately after addition of sugar, with an uptake of H(+) by the hexoseproton symport and charge compensation by K(+) loss from the cells and, to a smaller degree, by loss of another ion, probably a divalent cation. This phase coincided with strong membrane depolarization. Phase 2 started approximately 5 s after addition of sugar, when the acceleration of the H(+)-ATPase caused a slow-down of the K(+) efflux, a decrease in the cellular ATP level and an increase in respiration. The increased respiration was most probably responsible for a pronounced net acidification of the medium. This phase was inhibited in deuterium oxide. In phase 3, finally, a slow rate of net H(+) uptake and K(+) loss was established for several further minutes, together with a slight depolarization of the membrane. There was hardly any pH change in the cytoplasm, because the cytoplasmic buffering capacity was high enough to stabilize the pH for several minutes despite the net H(+) fluxes. The quantitative participation of the several phases of H(+) and K(+) flow depended on the pH of the medium, the ambient Ca(2+) concentration, and the metabolic fate of the transported sugar. The results indicate that the activity of the H(+)-ATPase never fully compensated for H(+) uptake by the sugar-symport system, because at least 10% of symport-caused charge inflow was compensated for by K(+) efflux. The restoration of pH in the cytoplasm and in the medium was probably achieved by metabolic reactions connected to increased glycolysis and respiration.
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Affiliation(s)
- E Komor
- Pflanzenphysiologie, Universität Bayreuth, D-8580, Bayreuth, Federal Republic of Germany
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Stanzel M, Sjolund RD, Komor E. Transport of glucose, fructose and sucrose by Streptanthus tortuosus suspension cells : II. Uptake at high sugar concentration. PLANTA 1988; 174:210-216. [PMID: 24221477 DOI: 10.1007/bf00394773] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/1987] [Accepted: 11/13/1987] [Indexed: 06/02/2023]
Abstract
In the concentration range above 1 mM a linear diffusion-like component of sugar uptake by Streptanthus suspension cells is observed. The rate of permeation is the same for sucrose, glucose, fructose and sorbitol, despite the very different uptake features of these sugars at low concentrations, where sorbitol and sucrose are not taken up at all and where different affinities for glucose and fructose are seen. The linear uptake component is responsible for 80% of sugar uptake at 100 mM, and it is an efficient permeation path for sucrose and fructose, which show poor permeation compared to glucose in the low concentration range. The mechanistic nature of the linear uptake component remains obscure: it is not directly dependent on metabolic energy (uncoupler does not inhibit it) and it is neither saturable up to 100 mM nor is it sugar-specific, but it is changeable, for instance, by plasmolysis or by protoplast generation. The permeation rates are very similar to those found in other plants for the linear component, but are much higher than in artificial membranes. These features are neither fully compatible with diffusion through a lipid phase nor with catalysed transport, and it is therefore suggested that this linear uptake proceeds through hydrophilic domains of the membrane. The linear uptake component will have consequences for apoplastic sugar concentration, sugar-accumulation factors and cell metabolism.
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Affiliation(s)
- M Stanzel
- Pflanzenphysiologie, Universität Bayreuth, Postfach 101251, D-8580, Bayreuth, Federal Republic of Germany
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Stanzel M, Sjolund RD, Komor E. Transport of glucose, fructose and sucrose by Streptanthus tortuosus suspension cells : I. Uptake at low sugar concentration. PLANTA 1988; 174:201-209. [PMID: 24221476 DOI: 10.1007/bf00394772] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/1987] [Accepted: 11/13/1987] [Indexed: 06/02/2023]
Abstract
Streptanthus tortuosus Kell. suspension cells will grow in a medium with sucrose as carbohydrate source. It was investigated whether the cells are able to take up sucrose or whether sucrose has to be hydrolyzed to glucose and fructose which eventually are taken up. The detailed quantitative analysis of sugar-uptake rates in the low concentration range up to 1 mM showed the following features: (i) There is definitely no sucrose-uptake system working in the low concentration range; any uptake of radioactivity from labelled sucrose proceeds via hydrolysis of sucrose by cell-wallbound invertase. (ii) Hexoses are taken up by two systems, a glucose-specific system with a K m of 45 μM and a high V max for glucose and a K m of 6 mM and a low V max for fructose, and a fructosespecific system with a K m of 500 μM and high a V max for fructose and a K m of 650 μM and a low V max for glucose. (iii) There is a more than tenfold preference for uptake of the fructose derived from sucrose versus uptake of free fructose, with the result that the kinetic disadvantage of the fructoseuptake system compared to the glucose-uptake system is diminished if sucrose is supplied as the carbon source. It is speculated that invertase might work as an enzyme aiding in fructose transport.
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Affiliation(s)
- M Stanzel
- Pflanzenphysiologie, Universität Bayreuth, Postfach 101251, D-8580, Bayreuth, Federal Republic of Germany
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Ullrich-Eberius CI, Novacky A, van Bel AJ. Phosphate uptake inLemna gibba G1: energetics and kinetics. PLANTA 1984; 161:46-52. [PMID: 24253554 DOI: 10.1007/bf00951459] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/1983] [Accepted: 12/21/1983] [Indexed: 05/28/2023]
Abstract
Phosphate uptake was studied by determining [(32)P]phosphate influx and by measurements of the electrical membrane potential in duckweed (Lemna gibba L.). Phosphate-induced membrane depolarization (ΔE m ) was controlled by the intracellular phosphate content, thus maximal ΔE m by 1 mM H2PO 4 (-) was up to 133 mV after 15d of phosphate starvation. The ΔE m was strongly dependent on the extracellular pH, with a sharp optimum at pH 5.7. It is suggested that phosphate uptake is energized by the electrochemical proton gradient, proceeding by a 2H(+)/H2PO 4 (-) contransport mechanism. This is supported also by the fusicoccin stimulation of phosphate influx. Kinetics of phosphate influx and of ΔE m , which represent mere plasmalemma transport, are best described by two Michaelis-Menten terms without any linear components.
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Affiliation(s)
- C I Ullrich-Eberius
- Institut für Botanik der Technischen Hochschule, Schnittspahnstrasse 3, D-6100, Darmstadt, Germany
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12
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Katou K, Tomiyama K, Okamoto H. Effects of hyphal wall components of Phytophthora infestans on membrane potential of potato tuber cells. ACTA ACUST UNITED AC 1982. [DOI: 10.1016/0048-4059(82)90065-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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van Bel AJ, Borstlap AC, van Pinxteren-Bazuine A, Ammerlaan A. Analysis of valine uptake by Commelina mesophyll cells in a biphasic active and a diffusional component. PLANTA 1982; 155:335-341. [PMID: 24271869 DOI: 10.1007/bf00429461] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/1982] [Accepted: 04/26/1982] [Indexed: 06/02/2023]
Abstract
Valine uptake by isolated Commelina benghalensis L. mesophyll cells was measured over a wide concentration range (10(-6)-4·10(-2) mol l(-1)). The uptake data were subjected to iterative fitting. Experiments with carbonyl cyanide mchlorophenyl hydrazone (CCCP), diethylstilbestrol (DES), and p-chloromercuriphenylsulphonic acid (PCMBS) provided evidence that the biphasic uptake kinetics of valine consists of a diffusional component and a biphasic active uptake. The data from the control experiments, were also best fitted to one diffusional component and two Michaelis-Menten systems. The presence of two carrier systems in the plasmalemma, however, was considered to be virtual for the following reasons: (1) Both phases of active uptake were equally decreased by high concentrations of K(+)-ions. (2) Fusicoccin stimulated the active uptake in both phases to the same extent. (3) Inhibitors of the proton-driven uptake (CCCP, DES, PCMBS) similarly inhibited the active uptake at all concentrations. (4) The active uptake equally responded in both phases to changes in the pH. (5) Light also promoted the active uptake over the whole concentration range. These results strongly indicate that, despite its biphasic character, the active uptake is due to one proton-driven carrier system.
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Affiliation(s)
- A J van Bel
- Botanisch Laboratorium, Rijksuniversiteit, Lange Nieuwstraat 106, NL-3512 PN, Utrecht, The Netherlands
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Amino Acid Uptake by Various Tissues of the Tomato Plant. Effects of the External pH and Light. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s0044-328x(81)80017-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Lüttge U, Jung KD, Ullrich-Eberius C. Evidence for Amino Acid-H+ Cotransport in Lemna gibba Given by Effects of Fusicoccin. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s0044-328x(81)80190-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Jung KD, Lüttge U. Amino acid uptake by Lemna gibba by a mechanism with affinity to neutral L-and D-amino acids. PLANTA 1980; 150:230-235. [PMID: 24306687 DOI: 10.1007/bf00390831] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/1980] [Accepted: 07/17/1980] [Indexed: 06/02/2023]
Abstract
Earlier work suggested that amino acid uptake by Lemna gibba cells is a H(+)-cotransport mechanism driven by a proton-electrochemical gradient at the plasmalemma. The present investigations of the transient membrane depolarizations elicited by amino acids and tracer-uptake experiments show that all neutral α-L-amino acids, D-alanine and analogues, like β-alanine and p-fluorophenylalanine, are transported by the same system. It remains to be seen if there are separate mechanisms for the uptake of acidic and basic amino acids.
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Affiliation(s)
- K D Jung
- Institut für Botanik, Technische Hochschule Darmstadt, Schnittspahnstraße 3-5, D-6100, Darmstadt, Federal Republic of Germany
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Van Bel A, Van Der Schoot C. Light-stimulated biphasic amino acid uptake by xylem parenchyma cells. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/0304-4211(80)90085-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Effect of fusicoccin on the membrane potential, on the uptake of glucose and glycine, and on the ATP level in Lemna gibba G1. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/0304-4211(80)90111-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Hartung W, Ullrich-Eberius CI, Lüttge U, Böcher M, Novacky A. Effect of abscisic acid on membrane potential and transport of glucose and glycine in Lemna gibba G1. PLANTA 1980; 148:256-261. [PMID: 24309828 DOI: 10.1007/bf00380036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/1979] [Accepted: 11/29/1979] [Indexed: 06/02/2023]
Abstract
The membrane potential of Lemna gibba G1 was measured with a microelectrode; glucose and glycine uptake were measured with (14)C-labeled substances. The membrane potential was increased by 85 mV on the average, after the plants had been pretreated with 10 μM abscisic acid (ABA) for more than 30 min. This effect is not linked to the endogenous level of soluble sugars. The concentration of these soluble sugars was increased to more than 200% by pretreatment of the plants with ABA, however, the respiration of the plants was not affected. ABA stimulated uptake of glucose and glycine. Glucose- and glycine-dependent depolarization and repolarization of the membrane was altered: depolarization was less and repolarization was slower; during uptake of glycine, the first typical phase of repolarization was suppressed. The data suggest that ABA interferes with the primary steps of substrate uptake.
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Affiliation(s)
- W Hartung
- Lehrstuhl Botanik I, Botanisches Institut, Mittlerer Dallenbergweg 64, D-8700, Würzburg, Germany
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Felle H, Bentrup FW. Hexose transport and membrane depolarization in Riccia fluitans. PLANTA 1980; 147:471-476. [PMID: 24311171 DOI: 10.1007/bf00380190] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/1979] [Accepted: 10/09/1979] [Indexed: 06/02/2023]
Abstract
In the aquatic liverwort Riccia fluitans, the uptake of (14)C-labeled 3-O-methyl glucose (3-OMG) and membrane depolarization (ΔΨ m ) caused by different hexoses has been studied as a function of time and concentration of hexose, K(+) and H(+), respectively. The rate of uptake of the non-metabolized 3-OMG shows two components: (A)A pH-dependent saturable uptake with a km value around 0.1 mM which saturates at 2.1 and 7.2 μmol G DW (-1) h(-1) at pH 6.8 and 5.0, respectively; and (B) a pH-insensitive uptake component which increases linearly with the external 3-OMG concentration and does not saturate ≦4 mM. Hexoses rapidly depolarize the plasmalemma of the thallus cell and increase its electrical conductance. The maximal ΔΨ m was 60±2 mV, the concentrations (mM) for half-maximal ΔΨ m were 0.24 glucose, 0.32 galactose, 0.37 2-deoxy glucose, 0.38 3-OMG, 0.57 mannose, and 34 fructose. In terms of a hexose carrier model and an equivalent circuit for the hexose-induced depolarized state of the membrane, it is proposed that a hexose carrier operates either electrogenically in its protonated, pH-and voltage-sensitive state, or by transmembrane diffusion of its uncharged state.
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Affiliation(s)
- H Felle
- Abteilung Biophysik der Pflanzen, Institut für Biologie I der Universität, Auf der Morgenstelle 1, D-7400, Tübingen, Federal Republic of Germany
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Novacky A, Ullrich-Eberius CI, Lüttge U. pH and membrane-potential changes during glucose uptake inLemna gibba G1 and their response to light. PLANTA 1980; 149:321-326. [PMID: 24306366 DOI: 10.1007/bf00571164] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/1979] [Accepted: 07/15/1980] [Indexed: 06/02/2023]
Abstract
Extracellular pH was measured with a microelectrode positioned over the lower surface of singleLemna gibba plants. Upon addition of glucose, a transient extracellular alkalinization occurred. Saturated extracellular pH changes were observed with 5 mM glucose. Simultaneously, the membrane potential difference of -250 mV in the dark measured with intracellular glass micropipettes, trnasiently decreased by 105 mV. Uptake of [(14)C]glucose and extracellular alkalinization was enhanced by light whereas glucose-induced membrane-potential changes were reduced in the light and became even smaller with increasing the preillumination time. Glucose uptake was optimal at pH 6. The results are taken as further evidence in favor of H(+)-glucose cotransport inLemna.
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Affiliation(s)
- A Novacky
- Department of Plant Pathology, University of Missouri-Columbia, 108 Waters Hall, 65211, Columbia, MO, USA
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Novacky A, Ullrich-Eberius CI, Lüttge U. Membrane potential changes during transport of hexoses in Lemna gibba G1. PLANTA 1978; 138:263-270. [PMID: 24414056 DOI: 10.1007/bf00386821] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/1977] [Accepted: 11/21/1977] [Indexed: 06/03/2023]
Abstract
The membrane potential (pd) of duck weed (Lemna gibba G1) proved to be energy dependent. At high internal ATP levels of 74 to 105 nmol ATP g(-1) FW, pd was between -175 and -265 mV. At low ATP levels of 23 to 46 nmol ATP g(-1) FW, pd was low, about -90 to -120 mV at pH 5.7, but -180 mV at pH 8. Upon addition of glucose in the dark or by light energy the low pd recovered to the high values. The active component of the pd was depolarized by the addition of hexoses in the dark and in the light. Hexose-dependent depolarization of the pd (=Δ pd) followed a saturation curve similar to active hexose influx kinetics. Depolarization of the pd recovered in the dark even in the presence of the hexoses and with a 10fold enhancement in the light. Depolarization and recovery could be repeated several times with the same cell. Glucose uptake caused a maximum depolarization of 133 mV, fructose uptake half that amount, sucrose had the same effect as glucose. During 3-O-methylglucose and 2-deoxyglucose uptake the depolarizing effect was only slightly lower. The pd remained unchanged in the presence of mannitol. The glucose dependent Δ pd and especially the rate of pd recovery proved to be pH-dependent between pH 4 and pH 8. It was independent of the presence of 1 mM KCl. Although no Δ pH could be measured in the incubation medium, these results can be best explained by a H(+)-hexose cotransport mechanism powered by active H(+) extrusion at the plasmalemma.
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Affiliation(s)
- A Novacky
- Department of Plant Pathology, University of Missouri, 65201, Columbia, MO, USA
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