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Xu H, Liang X, Lloyd JR, Chen Y. Visualizing calcium-dependent signaling networks in plants. Trends Plant Sci 2024; 29:117-119. [PMID: 37968199 DOI: 10.1016/j.tplants.2023.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 11/01/2023] [Accepted: 11/03/2023] [Indexed: 11/17/2023]
Abstract
Calcium-dependent protein kinases (CDPKs) are a multigene protein kinase family that have key regulatory roles in plants. However, imaging CDPK signals in plant cells remains challenging. The recently developed genetically encoded CDPK-Förster resonance energy transfer (FRET) reporter developed by Liese et al. allows visualization of calcium (Ca2+)-dependent conformational changes during activation or inactivation of CDPKs, providing a powerful tool for real-time monitoring of calcium decoding in plants.
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Affiliation(s)
- Huimin Xu
- State Key Laboratory of Plant Environmental Resilience, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xinlin Liang
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - James R Lloyd
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, 7600 Stellenbosch, South Africa
| | - Yanmei Chen
- State Key Laboratory of Plant Environmental Resilience, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
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2
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Thorpe CL, Crawford R, Hand RJ, Radford JT, Corkhill CL, Pearce CI, Neeway JJ, Plymale AE, Kruger AA, Morris K, Boothman C, Lloyd JR. Microbial interactions with phosphorus containing glasses representative of vitrified radioactive waste. J Hazard Mater 2024; 462:132667. [PMID: 37839373 DOI: 10.1016/j.jhazmat.2023.132667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 09/21/2023] [Accepted: 09/27/2023] [Indexed: 10/17/2023]
Abstract
The presence of phosphorus in borosilicate glass (at 0.1 - 1.3 mol% P2O5) and in iron-phosphate glass (at 53 mol% P2O5) stimulated the growth and metabolic activity of anaerobic bacteria in model systems. Dissolution of these phosphorus containing glasses was either inhibited or accelerated by microbial metabolic activity, depending on the solution chemistry and the glass composition. The breakdown of organic carbon to volatile fatty acids increased glass dissolution. The interaction of microbially reduced Fe(II) with phosphorus-containing glass under anoxic conditions decreased dissolution rates, whereas the interaction of Fe(III) with phosphorus-containing glass under oxic conditions increased glass dissolution. Phosphorus addition to borosilicate glasses did not significantly affect the microbial species present, however, the diversity of the microbial community was enhanced on the surface of the iron phosphate glass. Results demonstrate the potential for microbes to influence the geochemistry of radioactive waste disposal environments with implication for wasteform durability.
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Affiliation(s)
- C L Thorpe
- Immobilization Science Laboratory, Sir Robert Hadfield Building, University of Sheffield, S1 3JD, UK.
| | - R Crawford
- Immobilization Science Laboratory, Sir Robert Hadfield Building, University of Sheffield, S1 3JD, UK
| | - R J Hand
- Immobilization Science Laboratory, Sir Robert Hadfield Building, University of Sheffield, S1 3JD, UK
| | - J T Radford
- Immobilization Science Laboratory, Sir Robert Hadfield Building, University of Sheffield, S1 3JD, UK
| | - C L Corkhill
- Immobilization Science Laboratory, Sir Robert Hadfield Building, University of Sheffield, S1 3JD, UK; School of Earth Sciences, The University of Bristol, Bristol, UK
| | - C I Pearce
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - J J Neeway
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - A E Plymale
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - A A Kruger
- Office of River Protection, US Department of Energy, Richland, WA, USA
| | - K Morris
- Williamson Research Centre and Research Centre for Radwaste Disposal, Williamson Building, University of Manchester, 176 Oxford Road, M13 9PL, UK
| | - C Boothman
- Williamson Research Centre and Research Centre for Radwaste Disposal, Williamson Building, University of Manchester, 176 Oxford Road, M13 9PL, UK
| | - J R Lloyd
- Williamson Research Centre and Research Centre for Radwaste Disposal, Williamson Building, University of Manchester, 176 Oxford Road, M13 9PL, UK
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3
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Shalileh F, Gheibzadeh MS, Lloyd JR, Fietz S, Shahbani Zahiri H, Zolfaghari Emameh R. Evolutionary analysis and quality assessment of ζ-carbonic anhydrase sequences from environmental microbiome. J Basic Microbiol 2023; 63:1412-1425. [PMID: 37670218 DOI: 10.1002/jobm.202300323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 08/06/2023] [Accepted: 08/22/2023] [Indexed: 09/07/2023]
Abstract
Carbonic anhydrase (CA) is one of the most vital enzymes in living cells. This study has been performed due to the significance of this metalloenzyme for life and the novelty of some CA families like ζ-CA to evaluate evolutionary processes and quality check their sequences. In this study, bioinformatics methods revealed the presence of ζ-CA in some eukaryotic and prokaryotic microorganisms. Notably, it has not been previously reported in prokaryotes. The coexistence of β- and ζ-CAs in some microorganisms is also a novel finding as well. Also, our analysis identified several CA proteins with 6-14 amino acid intervals between histidine and cysteine in the second highly conserved motif, which can be classified as the novel ζ-CA subfamily members that emerged under the Zn deficiency of aquatic ecosystems and selection pressure in these environments. There is also a possibility that the achieved results are rooted in the contamination of samples from the environmental microbiome genome with genomes of diatom species and the occurrence of errors was observed in the DNA sequencing outcomes. Combining of all results from evolutionary analysis to quality control of ζ-CA DNA sequences is the incentive motivation to explore more the hidden aspects of ζ-CAs.
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Affiliation(s)
- Farzaneh Shalileh
- Department of Energy and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Mohammad S Gheibzadeh
- Department of Energy and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - James R Lloyd
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Susanne Fietz
- Department of Earth Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - Hossein Shahbani Zahiri
- Department of Energy and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Reza Zolfaghari Emameh
- Department of Energy and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
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Lloyd JR, Sonnewald U. Jens Kossmann 1963-2023 - a scientist with a passion for plant biology and people. Front Plant Sci 2023; 14:1266078. [PMID: 37680354 PMCID: PMC10481953 DOI: 10.3389/fpls.2023.1266078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 08/10/2023] [Indexed: 09/09/2023]
Affiliation(s)
- James R. Lloyd
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - Uwe Sonnewald
- Division of Biochemistry, Department of Biology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
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5
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Lloyd JR, Wilhelm R, Sharma MK, Kossmann J, Zhang P. Editorial: Insights in plant biotechnology: 2021. Front Plant Sci 2023; 14:1147930. [PMID: 36794210 PMCID: PMC9923401 DOI: 10.3389/fpls.2023.1147930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 01/19/2023] [Indexed: 06/18/2023]
Affiliation(s)
- James R. Lloyd
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - Ralf Wilhelm
- Institute for Biosafety in Plant Biotechnology, Julius Kühn-Institute - Federal Research Centre for Cultivated Plants, Quedlinburg, Germany
| | - Manoj K. Sharma
- Crop Genetics and Informatics Group, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Jens Kossmann
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - Peng Zhang
- CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
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Javal M, Terblanche JS, Benoit L, Conlong DE, Lloyd JR, Smit C, Chapuis MP. Does Host Plant Drive Variation in Microbial Gut Communities in a Recently Shifted Pest? Microb Ecol 2022:10.1007/s00248-022-02100-x. [PMID: 35997797 DOI: 10.1007/s00248-022-02100-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
Biotic interactions can modulate the responses of organisms to environmental stresses, including diet changes. Gut microbes have substantial effects on diverse ecological and evolutionary traits of their hosts, and microbial communities can be highly dynamic within and between individuals in space and time. Modulations of the gut microbiome composition and their potential role in the success of a species to maintain itself in a new environment have been poorly studied to date. Here we examine this question in a large wood-boring beetle Cacosceles newmannii (Cerambycidae), that was recently found thriving on a newly colonized host plant. Using 16S metabarcoding, we assessed the gut bacterial community composition of larvae collected in an infested field and in "common garden" conditions, fed under laboratory-controlled conditions on four either suspected or known hosts (sugarcane, tea tree, wattle, and eucalyptus). We analysed microbiome variation (i.e. diversity and differentiation), measured fitness-related larval growth, and studied host plant lignin and cellulose contents, since their degradation is especially challenging for wood-boring insects. We show that sugarcane seems to be a much more favourable host for larval growth. Bacterial diversity level was the highest in field-collected larvae, whereas lab-reared larvae fed on sugarcane showed a relatively low level of diversity but very specific bacterial variants. Bacterial communities were mainly dominated by Proteobacteria, but were significantly different between sugarcane-fed lab-reared larvae and any other hosts or field-collected larvae. We identified changes in the gut microbiome associated with different hosts over a short time frame, which support the hypothesis of a role of the microbiome in host switches.
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Affiliation(s)
- Marion Javal
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Stellenbosch University, Stellenbosch, South Africa.
- Current Address: CEFE, Univ Montpellier, CNRS, EPHE, Montpellier, IRD, France.
| | - John S Terblanche
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Stellenbosch University, Stellenbosch, South Africa
| | - Laure Benoit
- CBGP, Cirad, Montpellier SupAgro, INRA, IRD, Univ. Montpellier, Montpellier, France
| | - Desmond E Conlong
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Stellenbosch University, Stellenbosch, South Africa
- South African Sugarcane Research Institute, Mount Edgecombe, South Africa
| | - James R Lloyd
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - Chantelle Smit
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Stellenbosch University, Stellenbosch, South Africa
| | - Marie-Pierre Chapuis
- CBGP, Cirad, Montpellier SupAgro, INRA, IRD, Univ. Montpellier, Montpellier, France
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7
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Gabriel C, Fernhout J, Fichtner F, Feil R, Lunn JE, Kossmann J, Lloyd JR, van der Vyver C. Genetic manipulation of trehalose-6-phosphate synthase results in changes in the soluble sugar profile in transgenic sugarcane stems. Plant Direct 2021; 5:e358. [PMID: 34765864 PMCID: PMC8573382 DOI: 10.1002/pld3.358] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 10/05/2021] [Accepted: 10/15/2021] [Indexed: 05/11/2023]
Abstract
Trehalose is a non-reducing disaccharide widely distributed in nature. The trehalose biosynthetic intermediate, trehalose 6-phosphate (Tre6P) is an essential regulatory and signaling molecule involved in both regulation of carbon metabolism and photosynthesis. To investigate the effect of altered trehalose synthesis on sucrose accumulation in sugarcane (Saccharum spp. hybrid), we independently overexpressed the Escherichia coli otsA (trehalose-6-phosphate synthase; TPS) and otsB (trehalose-6-phosphate phosphatase; TPP) genes and additionally partially silenced native TPS expression. In mature cane, sucrose levels in the otsA transgenic plants were lowered, whereas sucrose levels in the otsB transgenic plants were increased. Partial silencing of TPS expression in sugarcane transformed with a TPS-targeted microRNA recombinant construct was confirmed in leaf and mature internode tissue of transgenic plants. Most of the silencing transgenic lines accumulated trehalose at lower levels than the wild-type (WT) plants. The immature stalk tissue of these transgenic lines had lower levels of glucose and fructose, whereas the mature internode tissue had lower sucrose and glucose levels, when compared with the WT. Furthermore, various minor metabolites and sugars were detected in the sugarcane plants, which mostly decreased as the stalk tissue of the cane matured. The results demonstrate that manipulation of Tre6P/trehalose metabolism has the potential to modify the profile of soluble sugars accumulated in sugarcane stems.
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Affiliation(s)
- Casey Gabriel
- Institute for Plant Biotechnology, Department of GeneticsUniversity of StellenboschStellenboschSouth Africa
| | - Jean‐Jacque Fernhout
- Institute for Plant Biotechnology, Department of GeneticsUniversity of StellenboschStellenboschSouth Africa
| | | | - Regina Feil
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - John E. Lunn
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - Jens Kossmann
- Institute for Plant Biotechnology, Department of GeneticsUniversity of StellenboschStellenboschSouth Africa
| | - James R. Lloyd
- Institute for Plant Biotechnology, Department of GeneticsUniversity of StellenboschStellenboschSouth Africa
| | - Christell van der Vyver
- Institute for Plant Biotechnology, Department of GeneticsUniversity of StellenboschStellenboschSouth Africa
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8
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Lloyd JR, Hogan A, Paschalis V, Bellamy-Carter J, Bottley A, Seymour GB, Hayes CJ, Oldham NJ. Mapping the interaction between eukaryotic initiation factor 4A (eIF4A) and the inhibitor hippuristanol using carbene footprinting and mass spectrometry. Proteomics 2021; 21:e2000288. [PMID: 34028182 DOI: 10.1002/pmic.202000288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 11/08/2022]
Abstract
Protein-ligand interactions are central to protein activity and cell functionality. Improved knowledge of these relationships greatly benefits our understanding of key biological processes and aids in rational drug design towards the treatment of clinically relevant diseases. Carbene footprinting is a recently developed mass spectrometry-based chemical labelling technique that provides valuable information relating to protein-ligand interactions, such as the mapping of binding sites and associated conformational change. Here, we show the application of carbene footprinting to the interaction between eIF4A helicase and a natural product inhibitor, hippuristanol, found in the coral Isis hippuris. Upon addition of hippuristanol we identified reduced carbene labelling (masking) in regions of eIF4A previously implicated in ligand binding. Additionally, we detected hippuristanol-associated increased carbene labelling (unmasking) around the flexible hinge region of eIF4A, indicating ligand-induced conformational change. This work represents further development of the carbene footprinting technique and demonstrates its potential in characterising medicinally relevant protein-ligand interactions.
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Affiliation(s)
- James R Lloyd
- School of Chemistry, University of Nottingham, Nottingham, UK
| | - Amy Hogan
- School of Chemistry, University of Nottingham, Nottingham, UK
| | - Vasileios Paschalis
- School of Chemistry, University of Nottingham, Nottingham, UK.,Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Jeddidiah Bellamy-Carter
- School of Chemistry, University of Nottingham, Nottingham, UK.,School of Biosciences, University of Birmingham, Birmingham, UK
| | - Andrew Bottley
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, UK
| | - Graham B Seymour
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, UK
| | | | - Neil J Oldham
- School of Chemistry, University of Nottingham, Nottingham, UK
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9
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10
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Abstract
This article comments on: Chia T, Chirico M, King R et al. 2019. A carbohydrate-binding protein, B-granule content 1 influences starch granule-size distribution in a dose dependent manner in polyploid wheat. Journal of Experimental Botany 70, 105–115.
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Affiliation(s)
- James R Lloyd
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
- Correspondence:
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11
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Mdodana NT, Jewell JF, Phiri EE, Smith ML, Oberlander K, Mahmoodi S, Kossmann J, Lloyd JR. Mutations in Glucan, Water Dikinase Affect Starch Degradation and Gametophore Development in the Moss Physcomitrella patens. Sci Rep 2019; 9:15114. [PMID: 31641159 PMCID: PMC6805951 DOI: 10.1038/s41598-019-51632-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 10/01/2019] [Indexed: 11/23/2022] Open
Abstract
The role of starch degradation in non-vascular plants is poorly understood. To expand our knowledge of this area, we have studied this process in Physcomitrella patens. This has been achieved through examination of the step known to initiate starch degradation in angiosperms, glucan phosphorylation, catalysed by glucan, water dikinase (GWD) enzymes. Phylogenetic analysis indicates that GWD isoforms can be divided into two clades, one of which contains GWD1/GWD2 and the other GWD3 isoforms. These clades split at a very early stage within plant evolution, as distinct sequences that cluster within each were identified in all major plant lineages. Of the five genes we identified within the Physcomitrella genome that encode GWD-like enzymes, two group within the GWD1/GWD2 clade and the others within the GWD3 clade. Proteins encoded by both loci in the GWD1/GWD2 clade, named PpGWDa and PpGWDb, are localised in plastids. Mutations of either PpGWDa or PpGWDb reduce starch phosphate abundance, however, a mutation at the PpGWDa locus had a much greater influence than one at PpGWDb. Only mutations affecting PpGWDa inhibited starch degradation. Mutants lacking this enzyme also failed to develop gametophores, a phenotype that could be chemically complemented using glucose supplementation within the growth medium.
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Affiliation(s)
- Ntombizanele T Mdodana
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Jonathan F Jewell
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Ethel E Phiri
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Marthinus L Smith
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Kenneth Oberlander
- Schweickerdt Herbarium, Department of Plant and Soil Sciences, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Saire Mahmoodi
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Jens Kossmann
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - James R Lloyd
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa.
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12
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Abstract
Starch is a plant storage polyglucan that accumulates in plastids. It is composed of two polymers, amylose and amylopectin, with different structures and plays several roles in helping to determine plant yield. In leaves, it acts as a buffer for night time carbon starvation. Genetically altered plants that cannot synthesize or degrade starch efficiently often grow poorly. There have been a number of successful approaches to manipulate leaf starch metabolism that has resulted in increased growth and yield. Its degradation is also a source of sugars that can help alleviate abiotic stress. In edible parts of plants, starch often makes up the majority of the dry weight constituting much of the calorific value of food and feed. Increasing starch in these organs can increase this as well as increasing yield. Enzymes involved in starch metabolism are well known, and there has been much research analyzing their functions in starch synthesis and degradation, as well as genetic and posttranslational regulatory mechanisms affecting them. In this mini review, we examine work on this topic and discuss future directions that could be used to manipulate this metabolite for improved yield.
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Affiliation(s)
| | - Jens Kossmann
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
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Pholo M, Coetzee B, Maree HJ, Young PR, Lloyd JR, Kossmann J, Hills PN. Cell division and turgor mediate enhanced plant growth in Arabidopsis plants treated with the bacterial signalling molecule lumichrome. Planta 2018; 248:477-488. [PMID: 29777364 DOI: 10.1007/s00425-018-2916-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
Transcriptomic analysis indicates that the bacterial signalling molecule lumichrome enhances plant growth through a combination of enhanced cell division and cell enlargement, and possibly enhances photosynthesis. Lumichrome (7,8 dimethylalloxazine), a novel multitrophic signal molecule produced by Sinorhizobium meliloti bacteria, has previously been shown to elicit growth promotion in different plant species (Phillips et al. in Proc Natl Acad Sci USA 96:12275-12280, https://doi.org/10.1073/pnas.96.22.12275 , 1999). However, the molecular mechanisms that underlie this plant growth promotion remain obscure. Global transcript profiling using RNA-seq suggests that lumichrome enhances growth by inducing genes impacting on turgor driven growth and mitotic cell cycle that ensures the integration of cell division and expansion of developing leaves. The abundance of XTH9 and XPA4 transcripts was attributed to improved mediation of cell-wall loosening to allow turgor-driven cell enlargement. Mitotic CYCD3.3, CYCA1.1, SP1L3, RSW7 and PDF1 transcripts were increased in lumichrome-treated Arabidopsis thaliana plants, suggesting enhanced growth was underpinned by increased cell differentiation and expansion with a consequential increase in biomass. Synergistic ethylene-auxin cross-talk was also observed through reciprocal over-expression of ACO1 and SAUR54, in which ethylene activates the auxin signalling pathway and regulates Arabidopsis growth by both stimulating auxin biosynthesis and modulating the auxin transport machinery to the leaves. Decreased transcription of jasmonate biosynthesis and responsive-related transcripts (LOX2; LOX3; LOX6; JAL34; JR1) might contribute towards suppression of the negative effects of methyl jasmonate (MeJa) such as chlorophyll loss and decreases in RuBisCO and photosynthesis. This work contributes towards a deeper understanding of how lumichrome enhances plant growth and development.
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Affiliation(s)
- Motlalepula Pholo
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
| | - Beatrix Coetzee
- Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
- Agricultural Research Council, Infruitec-Nietvoorbij, Institute for Deciduous Fruit, Vines and Wine, Private Bag X5026, Stellenbosch, 7599, South Africa
| | - Hans J Maree
- Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
- Agricultural Research Council, Infruitec-Nietvoorbij, Institute for Deciduous Fruit, Vines and Wine, Private Bag X5026, Stellenbosch, 7599, South Africa
| | - Philip R Young
- Institute for Wine Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
| | - James R Lloyd
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
| | - Jens Kossmann
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
| | - Paul N Hills
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.
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14
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Samodien E, Jewell JF, Loedolff B, Oberlander K, George GM, Zeeman SC, Damberger FF, van der Vyver C, Kossmann J, Lloyd JR. Repression of Sex4 and Like Sex Four2 Orthologs in Potato Increases Tuber Starch Bound Phosphate With Concomitant Alterations in Starch Physical Properties. Front Plant Sci 2018; 9:1044. [PMID: 30083175 PMCID: PMC6064929 DOI: 10.3389/fpls.2018.01044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 06/27/2018] [Indexed: 05/25/2023]
Abstract
To examine the roles of starch phosphatases in potatoes, transgenic lines were produced where orthologs of SEX4 and LIKE SEX FOUR2 (LSF2) were repressed using RNAi constructs. Although repression of either SEX4 or LSF2 inhibited leaf starch degradation, it had no effect on cold-induced sweetening in tubers. Starch amounts were unchanged in the tubers, but the amount of phosphate bound to the starch was significantly increased in all the lines, with phosphate bound at the C6 position of the glucosyl units increased in lines repressed in StSEX4 and in the C3 position in lines repressed in StLSF2 expression. This was accompanied by a reduction in starch granule size and an alteration in the constituent glucan chain lengths within the starch molecule, although no obvious alteration in granule morphology was observed. Starch from the transgenic lines contained fewer chains with a degree of polymerization (DP) of less than 17 and more with a DP between 17 and 38. There were also changes in the physical properties of the starches. Rapid viscoanalysis demonstrated that both the holding strength and the final viscosity of the high phosphate starches were increased indicating that the starches have increased swelling power due to an enhanced capacity for hydration.
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Affiliation(s)
- Ebrahim Samodien
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
| | - Jonathan F. Jewell
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
| | - Bianke Loedolff
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
| | - Kenneth Oberlander
- Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, South Africa
| | - Gavin M. George
- Institute of Molecular Plant Biology, ETH Zürich, Zürich, Switzerland
| | - Samuel C. Zeeman
- Institute of Molecular Plant Biology, ETH Zürich, Zürich, Switzerland
| | - Fred F. Damberger
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
- Biomolecular NMR Spectroscopy Platform, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Christell van der Vyver
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
| | - Jens Kossmann
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
| | - James R. Lloyd
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
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Tridgett M, Lloyd JR, Kennefick J, Moore-Kelly C, Dafforn TR. Mutation of M13 Bacteriophage Major Coat Protein for Increased Conjugation to Exogenous Compounds. Bioconjug Chem 2018; 29:1872-1875. [PMID: 29800521 DOI: 10.1021/acs.bioconjchem.8b00307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Over the past ten years there has been increasing interest in the conjugation of exogenous compounds to the surface of the M13 bacteriophage. M13 offers a convenient scaffold for the development of nanoassemblies with useful functions, such as highly specific drug delivery and pathogen detection. However, the progress of these technologies has been hindered by the limited efficiency of conjugation to the bacteriophage. Here we generate a mutant version of M13 with an additional lysine residue expressed on the outer surface of the M13 major coat protein, pVIII. We show that this mutation is accommodated by the bacteriophage and that up to an additional 520 exogenous groups can be attached to the bacteriophage surface via amine-directed conjugation. These results could aid the development of high payload drug delivery nanoassemblies and pathogen detection systems with increased sensitivity.
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Affiliation(s)
- Matthew Tridgett
- School of Biosciences , University of Birmingham , Edgbaston, Birmingham , West Midlands , B15 2TT , United Kingdom
| | - James R Lloyd
- School of Biosciences , University of Birmingham , Edgbaston, Birmingham , West Midlands , B15 2TT , United Kingdom
| | - Jack Kennefick
- School of Biosciences , University of Birmingham , Edgbaston, Birmingham , West Midlands , B15 2TT , United Kingdom
| | - Charles Moore-Kelly
- School of Biosciences , University of Birmingham , Edgbaston, Birmingham , West Midlands , B15 2TT , United Kingdom
| | - Timothy R Dafforn
- School of Biosciences , University of Birmingham , Edgbaston, Birmingham , West Midlands , B15 2TT , United Kingdom
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16
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Wang W, Hostettler CE, Damberger FF, Kossmann J, Lloyd JR, Zeeman SC. Modification of Cassava Root Starch Phosphorylation Enhances Starch Functional Properties. Front Plant Sci 2018; 9:1562. [PMID: 30425722 PMCID: PMC6218586 DOI: 10.3389/fpls.2018.01562] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/05/2018] [Indexed: 05/10/2023]
Abstract
Cassava (Manihot esculenta Crantz) is a root crop used as a foodstuff and as a starch source in industry. Starch functional properties are influenced by many structural features including the relative amounts of the two glucan polymers amylopectin and amylose, the branched structure of amylopectin, starch granule size and the presence of covalent modifications. Starch phosphorylation, where phosphates are linked either to the C3 or C6 carbon atoms of amylopectin glucosyl residues, is a naturally occurring modification known to be important for starch remobilization. The degree of phosphorylation has been altered in several crops using biotechnological approaches to change expression of the starch-phosphorylating enzyme GLUCAN WATER DIKINASE (GWD). Interestingly, this frequently alters other structural features of starch beside its phosphate content. Here, we aimed to alter starch phosphorylation in cassava storage roots either by manipulating the expression of the starch phosphorylating or dephosphorylating enzymes. Therefore, we generated transgenic plants in which either the wild-type potato GWD (StGWD) or a redox-insensitive version of it were overexpressed. Further plants were created in which we used RNAi to silence each of the endogenous phosphoglucan phosphatase genes STARCH EXCESS 4 (MeSEX4) and LIKE SEX4 2 (MeLSF), previously discovered by analyzing leaf starch metabolism in the model species Arabidopsis thaliana. Overexpressing the potato GWD gene (StGWD), which specifically phosphorylates the C6 position, increased the total starch-bound phosphate content at both the C6 and the C3 positions. Silencing endogenous LSF2 gene (MeLSF2), which specifically dephosphorylates the C3 position, increased the ratio of C3:C6 phosphorylation, showing that its function is conserved in storage tissues. In both cases, other structural features of starch (amylopectin structure, amylose content and starch granule size) were unaltered. This allowed us to directly relate the physicochemical properties of the starch to its phosphate content or phosphorylation pattern. Starch swelling power and paste clarity were specifically influenced by total phosphate content. However, phosphate position did not significantly influence starch functional properties. In conclusion, biotechnological manipulation of starch phosphorylation can specifically alter certain cassava storage root starch properties, potentially increasing its value in food and non-food industries.
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Affiliation(s)
- Wuyan Wang
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Carmen E. Hostettler
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Fred F. Damberger
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
- Biomolecular NMR Spectroscopy Platform, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Jens Kossmann
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
| | - James R. Lloyd
- Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Stellenbosch, South Africa
| | - Samuel C. Zeeman
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
- *Correspondence: Samuel C. Zeeman,
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17
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Strydom L, Jewell J, Meier MA, George GM, Pfister B, Zeeman S, Kossmann J, Lloyd JR. Analysis of genes involved in glycogen degradation in Escherichia coli. FEMS Microbiol Lett 2017; 364:fnx016. [PMID: 28119371 DOI: 10.1093/femsle/fnx016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2017] [Indexed: 11/12/2022] Open
Abstract
Escherichia coli accumulate or degrade glycogen depending on environmental carbon supply. Glycogen phosphorylase (GlgP) and glycogen debranching enzyme (GlgX) are known to act on the glycogen polymer, while maltodextrin phosphorylase (MalP) is thought to remove maltodextrins released by GlgX. To examine the roles of these enzymes in more detail, single, double and triple mutants lacking all their activities were produced. GlgX and GlgP were shown to act directly on the glycogen polymer, while MalP most likely catabolised soluble malto-oligosaccharides. Interestingly, analysis of a triple mutant lacking all three enzymes indicates the presence of another enzyme that can release maltodextrins from glycogen.
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Affiliation(s)
- Lindi Strydom
- Institute for Plant Biotechnology, Department of Genetics, University of Stellenbosch, Private Bag X1, Matieland 7602, Stellenbosch, South Africa
| | - Jonathan Jewell
- Institute for Plant Biotechnology, Department of Genetics, University of Stellenbosch, Private Bag X1, Matieland 7602, Stellenbosch, South Africa
| | - Michael A Meier
- Institute for Plant Biotechnology, Department of Genetics, University of Stellenbosch, Private Bag X1, Matieland 7602, Stellenbosch, South Africa
| | - Gavin M George
- Institute for Agricultural Sciences, ETH Zurich, 8092 Zurich, Switzerland
| | - Barbara Pfister
- Institute for Agricultural Sciences, ETH Zurich, 8092 Zurich, Switzerland
| | - Samuel Zeeman
- Institute for Agricultural Sciences, ETH Zurich, 8092 Zurich, Switzerland
| | - Jens Kossmann
- Institute for Plant Biotechnology, Department of Genetics, University of Stellenbosch, Private Bag X1, Matieland 7602, Stellenbosch, South Africa
| | - James R Lloyd
- Institute for Plant Biotechnology, Department of Genetics, University of Stellenbosch, Private Bag X1, Matieland 7602, Stellenbosch, South Africa
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18
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Basavalingappa A, Shen MY, Lloyd JR. Modeling the copper microstructure and elastic anisotropy and studying its impact on reliability in nanoscale interconnects. ACTA ACUST UNITED AC 2017. [DOI: 10.1186/s40759-017-0021-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Abstract
Background
Copper is the primary metal used in integrated circuit manufacturing of today. Even though copper is face centered cubic it has significant mechanical anisotropy depending on the crystallographic orientations. Copper metal lines in integrated circuits are polycrystalline and typically have lognormal grain size distribution. The polycrystalline microstructure is known to impact the reliability and must be considered in modeling for better understanding of the failure mechanisms.
Methods
In this work, we used Voronoi tessellation to model the polycrystalline microstructure with lognormal grainsize distribution for the copper metal lines in test structures. Each of the grains is then assigned an orientation with distinct probabilistic texture and corresponding anisotropic elastic constants based on the assigned orientation. The test structure is then subjected to a thermal stress.
Results
A significant variation in hydrostatic stresses at the grain boundaries is observed by subjecting the test structure to thermal stress due to the elastic anisotropy of copper. This introduces new weak points within the metal interconnects leading to failure.
Conclusions
Inclusion of microstructures and corresponding anisotropic properties for copper grains is crucial to conduct a realistic study of stress voiding, hillock formation, delamination, and electromigration phenomena, especially at smaller nodes where the anisotropic effects are significant.
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Byrne JM, Muhamadali H, Coker VS, Cooper J, Lloyd JR. Scale-up of the production of highly reactive biogenic magnetite nanoparticles using Geobacter sulfurreducens. J R Soc Interface 2016; 12:rsif.2015.0240. [PMID: 25972437 PMCID: PMC4590511 DOI: 10.1098/rsif.2015.0240] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although there are numerous examples of large-scale commercial microbial synthesis routes for organic bioproducts, few studies have addressed the obvious potential for microbial systems to produce inorganic functional biomaterials at scale. Here we address this by focusing on the production of nanoscale biomagnetite particles by the Fe(III)-reducing bacterium Geobacter sulfurreducens, which was scaled up successfully from laboratory- to pilot plant-scale production, while maintaining the surface reactivity and magnetic properties which make this material well suited to commercial exploitation. At the largest scale tested, the bacterium was grown in a 50 l bioreactor, harvested and then inoculated into a buffer solution containing Fe(III)-oxyhydroxide and an electron donor and mediator, which promoted the formation of magnetite in under 24 h. This procedure was capable of producing up to 120 g of biomagnetite. The particle size distribution was maintained between 10 and 15 nm during scale-up of this second step from 10 ml to 10 l, with conserved magnetic properties and surface reactivity; the latter demonstrated by the reduction of Cr(VI). The process presented provides an environmentally benign route to magnetite production and serves as an alternative to harsher synthetic techniques, with the clear potential to be used to produce kilogram to tonne quantities.
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Affiliation(s)
- J M Byrne
- School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK Geomicrobiology, Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany
| | - H Muhamadali
- School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK
| | - V S Coker
- School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK
| | - J Cooper
- The Centre for Process Innovation, CPI, Wilton Centre, Wilton, Redcar TS10 4RF, UK
| | - J R Lloyd
- School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK
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20
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Abstract
Here we describe the methodology of using virus-induced gene silencing (VIGS) as a powerful and scalable tool to screen the function of genes that participate in adaptation to drought. Silencing of endogenous gene expression in Nicotiana benthamiana is achieved by systemic infection of the aerial parts of the plant with a virus engineered to contain homologous fragments of the target gene(s) of interest. Silenced plant material can be consistently produced with little optimization in less than 1 month without specialized equipment, using only simple cloning and transformation techniques. Although maximal silencing is localized to only a few leaves, when whole plants are subjected to water stress, the tissue from these silenced leaves can be characterized for physiological, biochemical, and transcriptional responses to determine the role of the candidate genes in drought tolerance.
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Affiliation(s)
- Gavin M George
- Department of Biology, ETH Zurich, Universitaetsstrasse 2, Zurich, CH-8092, Switzerland
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21
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Coker VS, Garrity A, Wennekes WB, Roesink HDW, Cutting RS, Lloyd JR. Cr(VI) and azo dye removal using a hollow-fibre membrane system functionalized with a biogenic Pd-magnetite catalyst. Environ Technol 2014; 35:1046-1054. [PMID: 24645489 DOI: 10.1080/09593330.2013.859738] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This study investigates the application of a hybrid system combining hollow-fibre membrane technology with the reductive abilities of magnetic nanoparticles for the remediation of toxic Cr(VI) and the azo dye, Remazol Black B. Nano-scale biogenic magnetite (Fe3O4), formed by microbial reduction of the mineral ferrihydrite, has a high reductive capacity due to the presence of Fe(II) in the mineral structure. The magnetic nanoparticles (approximately 20 nm) can be arrayed with Pd0 nanoparticles (approximately 5 nm) making a catalytically active nanomaterial. Membrane units, with and without nanoparticles, were challenged with either Cr(VI) or azo dye and some were supplemented with sodium formate, as an electron donor for contaminant reduction promoted by the Pd. The combination of Pd-magnetite with formate resulted in the most effective remediation strategy for both contaminants and the lifetime of the membrane unit was also increased, with 55% (19 days) and 70% (23 days) removal of the azo dye and Cr(VI), respectively. Low flow rates of 0.1 ml/min resulted in improved efficiencies due to increased contact time with the membrane/nanoparticle unit, with 70-75% removal of each contaminant. Chemical analyses of the nanoparticles post-exposure to Cr(VI) in the membrane modules indicated Pd to be more oxidized when Cr removal was maximized, and that the Cr was partially reduced to Cr(III) at the surface of the magnetite. These results have demonstrated that hollow-fibre membrane units can be enhanced for the removal of soluble, redox sensitive contaminants by incorporation of a layer of palladized biogenic nanoparticulate magnetite.
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22
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Byrne JM, Coker VS, Moise S, Wincott PL, Vaughan DJ, Tuna F, Arenholz E, van der Laan G, Pattrick RAD, Lloyd JR, Telling ND. Controlled cobalt doping in biogenic magnetite nanoparticles. J R Soc Interface 2013; 10:20130134. [PMID: 23594814 PMCID: PMC3645421 DOI: 10.1098/rsif.2013.0134] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 03/25/2013] [Indexed: 12/15/2022] Open
Abstract
Cobalt-doped magnetite (CoxFe3 -xO4) nanoparticles have been produced through the microbial reduction of cobalt-iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe(2+) site with Co(2+), with up to 17 per cent Co substituted into tetrahedral sites.
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Affiliation(s)
- J M Byrne
- School of Earth, Atmospheric and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester, UK.
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23
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Fellowes JW, Pattrick RAD, Lloyd JR, Charnock JM, Coker VS, Mosselmans JFW, Weng TC, Pearce CI. Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors. Nanotechnology 2013; 24:145603. [PMID: 23508116 DOI: 10.1088/0957-4484/24/14/145603] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Luminescent quantum dots were synthesized using bacterially derived selenide (Se(II-)) as the precursor. Biogenic Se(II-) was produced by the reduction of Se(IV) by Veillonella atypica and compared directly against borohydride-reduced Se(IV) for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological Se(II-) formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic Se(II-) included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic Se(II-) is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.
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Affiliation(s)
- J W Fellowes
- School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, Williamson Building, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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24
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Coker VS, Byrne JM, Telling ND, VAN DER Laan G, Lloyd JR, Hitchcock AP, Wang J, Pattrick RAD. Characterisation of the dissimilatory reduction of Fe(III)-oxyhydroxide at the microbe-mineral interface: the application of STXM-XMCD. Geobiology 2012; 10:347-354. [PMID: 22515480 DOI: 10.1111/j.1472-4669.2012.00329.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A combination of scanning transmission X-ray microscopy and X-ray magnetic circular dichroism was used to spatially resolve the distribution of different carbon and iron species associated with Shewanella oneidensis MR-1 cells. S. oneidensis MR-1 couples the reduction of Fe(III)-oxyhydroxides to the oxidation of organic matter in order to conserve energy for growth. Several potential mechanisms may be used by S. oneidensis MR-1 to facilitate Fe(III)-reduction. These include direct contact between the cell and mineral surface, secretion of either exogenous electron shuttles or Fe-chelating agents and the production of conductive 'nanowires'. In this study, the protein/lipid signature of the bacterial cells was associated with areas of magnetite (Fe₃O₄), the product of dissimilatory Fe(III) reduction, which was oversaturated with Fe(II) (compared to stoichiometric magnetite). However, areas of the sample rich in polysaccharides, most likely associated with extracellular polymeric matrix and not in direct contact with the cell surface, were undersaturated with Fe(II), forming maghemite-like (γ-Fe₂O₃) phases compared to stoichiometric magnetite. The reduced form of magnetite will be much more effective in environmental remediation such as the immobilisation of toxic metals. These findings suggest a dominant role for surface contact-mediated electron transfer in this study and also the inhomogeneity of magnetite species on the submicron scale present in microbial reactions. This study also illustrates the applicability of this new synchrotron-based technique for high-resolution characterisation of the microbe-mineral interface, which is pivotal in controlling the chemistry of the Earth's critical zone.
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Affiliation(s)
- V S Coker
- School of Earth, Atmospheric & Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester, UK
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25
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George GM, Bauer R, Blennow A, Kossmann J, Lloyd JR. Virus-induced multiple gene silencing to study redundant metabolic pathways in plants: silencing the starch degradation pathway in Nicotiana benthamiana. Biotechnol J 2012; 7:884-90. [PMID: 22345045 DOI: 10.1002/biot.201100469] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 01/31/2012] [Accepted: 02/14/2012] [Indexed: 01/25/2023]
Abstract
Virus-induced gene silencing (VIGS) is a rapid technique that allows for specific and reproducible post-transcriptional degradation of targeted mRNA. The method has been proven efficient for suppression of expression of many single enzymes. The metabolic networks of plants, however, often contain isoenzymes and gene families that are able to compensate for a mutation and mask the development of a silencing phenotype. Here, we show the application of multiple gene VIGS repression for the study of these redundant biological pathways. Several genes in the starch degradation pathway [disproportionating enzyme 1; (DPE1), disproportionating enzyme 2 (DPE2), and GWD] were silenced. The functionally distinct DPE enzymes are present in alternate routes for sugar export to the cytoplasm and result in an increase in starch production when silenced individually. Simultaneous silencing of DPE1 and DPE2 in Nicotiana benthamiana resulted in a near complete suppression in starch and accumulation of malto-oligosaccharides.
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Affiliation(s)
- Gavin M George
- Genetics Department, Institute for Plant Biotechnology, Stellenbosch University, Matieland, South Africa.
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26
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Gouws LM, Botes E, Wiese AJ, Trenkamp S, Torres-Jerez I, Tang Y, Hills PN, Usadel B, Lloyd JR, Fernie AR, Kossmann J, van der Merwe MJ. The plant growth promoting substance, lumichrome, mimics starch, and ethylene-associated symbiotic responses in lotus and tomato roots. Front Plant Sci 2012; 3:120. [PMID: 22701462 PMCID: PMC3371600 DOI: 10.3389/fpls.2012.00120] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 05/18/2012] [Indexed: 05/08/2023]
Abstract
Symbiosis involves responses that maintain the plant host and symbiotic partner's genetic program; yet these cues are far from elucidated. Here we describe the effects of lumichrome, a flavin identified from Rhizobium spp., applied to lotus (Lotus japonicus) and tomato (Solanum lycopersicum). Combined transcriptional and metabolite analyses suggest that both species shared common pathways that were altered in response to this application under replete, sterile conditions. These included genes involved in symbiosis, as well as transcriptional and metabolic responses related to enhanced starch accumulation and altered ethylene metabolism. Lumichrome priming also resulted in altered colonization with either Mesorhizobium loti (for lotus) or Glomus intraradices/G. mossea (for tomato). It enhanced nodule number but not nodule formation in lotus; while leading to enhanced hyphae initiation and delayed arbuscule maturation in tomato.
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Affiliation(s)
- Liezel M. Gouws
- Institute of Plant Biotechnology, Department of Genetics, Stellenbosch UniversityStellenbosch, South Africa
| | - Eileen Botes
- Institute of Plant Biotechnology, Department of Genetics, Stellenbosch UniversityStellenbosch, South Africa
| | - Anna J. Wiese
- Institute of Plant Biotechnology, Department of Genetics, Stellenbosch UniversityStellenbosch, South Africa
| | - Sandra Trenkamp
- Max-Planck Institute of Molecular Plant PhysiologyPotsdam-Golm, Germany
| | | | - Yuhong Tang
- The Samuel Roberts Noble FoundationArdmore, OK, USA
| | - Paul N. Hills
- Institute of Plant Biotechnology, Department of Genetics, Stellenbosch UniversityStellenbosch, South Africa
| | - Björn Usadel
- Max-Planck Institute of Molecular Plant PhysiologyPotsdam-Golm, Germany
| | - James R. Lloyd
- Institute of Plant Biotechnology, Department of Genetics, Stellenbosch UniversityStellenbosch, South Africa
| | | | - Jens Kossmann
- Institute of Plant Biotechnology, Department of Genetics, Stellenbosch UniversityStellenbosch, South Africa
| | - Margaretha J. van der Merwe
- Institute of Plant Biotechnology, Department of Genetics, Stellenbosch UniversityStellenbosch, South Africa
- Max-Planck Institute of Molecular Plant PhysiologyPotsdam-Golm, Germany
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27
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Byrne JM, Telling ND, Coker VS, Pattrick RAD, van der Laan G, Arenholz E, Tuna F, Lloyd JR. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens. Nanotechnology 2011; 22:455709. [PMID: 22020365 DOI: 10.1088/0957-4484/22/45/455709] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.
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Affiliation(s)
- J M Byrne
- School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK.
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28
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Fellowes JW, Pattrick RAD, Green DI, Dent A, Lloyd JR, Pearce CI. Use of biogenic and abiotic elemental selenium nanospheres to sequester elemental mercury released from mercury contaminated museum specimens. J Hazard Mater 2011; 189:660-669. [PMID: 21300433 DOI: 10.1016/j.jhazmat.2011.01.079] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 01/14/2011] [Accepted: 01/17/2011] [Indexed: 05/30/2023]
Abstract
Mercuric chloride solutions have historically been used as pesticides to prevent bacterial, fungal and insect degradation of herbarium specimens. The University of Manchester museum herbarium contains over a million specimens from numerous collections, many preserved using HgCl(2) and its transformation to Hg(v)(0) represents a health risk to herbarium staff. Elevated mercury concentrations in work areas (∼ 1.7 μg m(-3)) are below advised safe levels (<25 μg m(-3)) but up to 90 μg m(-3) mercury vapour was measured in specimen boxes, representing a risk when accessing the samples. Mercury vapour release correlated strongly with temperature. Mercury salts were observed on botanical specimens at concentrations up to 2.85 wt% (bulk); XPS, SEM-EDS and XANES suggest the presence of residual HgCl(2) as well as cubic HgS and HgO. Bacterially derived, amorphous nanospheres of elemental selenium effectively sequestered the mercury vapour in the specimen boxes (up to 19 wt%), and analysis demonstrated that the Hg(v)(0) was oxidised by the selenium to form stable HgSe on the surface of the nanospheres. Biogenic Se(0) can be used to reduce Hg(v)(0) in long term, slow release environments.
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Affiliation(s)
- J W Fellowes
- School of Earth, Atmospheric and Environmental Sciences, Williamson Building, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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Lütken H, Lloyd JR, Glaring MA, Baunsgaard L, Laursen KH, Haldrup A, Kossmann J, Blennow A. Repression of both isoforms of disproportionating enzyme leads to higher malto-oligosaccharide content and reduced growth in potato. Planta 2010; 232:1127-39. [PMID: 20700743 DOI: 10.1007/s00425-010-1245-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 07/29/2010] [Indexed: 05/29/2023]
Abstract
Two glucanotransferases, disproportionating enzyme 1 (StDPE1) and disproportionating enzyme 2 (StDPE2), were repressed using RNA interference technology in potato, leading to plants repressed in either isoform individually, or both simultaneously. This is the first detailed report of their combined repression. Plants lacking StDPE1 accumulated slightly more starch in their leaves than control plants and high levels of maltotriose, while those lacking StDPE2 contained maltose and large amounts of starch. Plants repressed in both isoforms accumulated similar amounts of starch to those lacking StDPE2. In addition, they contained a range of malto-oligosaccharides from maltose to maltoheptaose. Plants repressed in both isoforms had chlorotic leaves and did not grow as well as either the controls or lines where only one of the isoforms was repressed. Examination of photosynthetic parameters suggested that this was most likely due to a decrease in carbon assimilation. The subcellular localisation of StDPE2 was re-addressed in parallel with DPE2 from Arabidopsis thaliana by transient expression of yellow fluorescent protein fusions in tobacco. No translocation to the chloroplasts was observed for any of the fusion proteins, supporting a cytosolic role of the StDPE2 enzyme in leaf starch metabolism, as has been observed for Arabidopsis DPE2. It is concluded that StDPE1 and StDPE2 have individual essential roles in starch metabolism in potato and consequently repression of these disables regulation of leaf malto-oligosaccharides, starch content and photosynthetic activity and thereby plant growth possibly by a negative feedback mechanism.
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Affiliation(s)
- Henrik Lütken
- Department of Plant Biology and Biotechnology, University of Copenhagen, Frederiksberg C, Denmark.
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George GM, van der Merwe MJ, Nunes-Nesi A, Bauer R, Fernie AR, Kossmann J, Lloyd JR. Virus-induced gene silencing of plastidial soluble inorganic pyrophosphatase impairs essential leaf anabolic pathways and reduces drought stress tolerance in Nicotiana benthamiana. Plant Physiol 2010; 154:55-66. [PMID: 20605913 PMCID: PMC2938153 DOI: 10.1104/pp.110.157776] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 07/02/2010] [Indexed: 05/18/2023]
Abstract
The role of pyrophosphate in primary metabolism is poorly understood. Here, we report on the transient down-regulation of plastid-targeted soluble inorganic pyrophosphatase in Nicotiana benthamiana source leaves. Physiological and metabolic perturbations were particularly evident in chloroplastic central metabolism, which is reliant on fast and efficient pyrophosphate dissipation. Plants lacking plastidial soluble inorganic pyrophosphatase (psPPase) were characterized by increased pyrophosphate levels, decreased starch content, and alterations in chlorophyll and carotenoid biosynthesis, while constituents like amino acids (except for histidine, serine, and tryptophan) and soluble sugars and organic acids (except for malate and citrate) remained invariable from the control. Furthermore, translation of Rubisco was significantly affected, as observed for the amounts of the respective subunits as well as total soluble protein content. These changes were concurrent with the fact that plants with reduced psPPase were unable to assimilate carbon to the same extent as the controls. Furthermore, plants with lowered psPPase exposed to mild drought stress showed a moderate wilting phenotype and reduced vitality, which could be correlated to reduced abscisic acid levels limiting stomatal closure. Taken together, the results suggest that plastidial pyrophosphate dissipation through psPPase is indispensable for vital plant processes.
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Affiliation(s)
| | | | | | | | | | | | - James R. Lloyd
- Institute of Plant Biotechnology, University of Stellenbosch, Matieland 7602, Stellenbosch, South Africa (G.M.G., M.J.v.d.M., R.B., J.K., J.R.L.); Max Planck Institute of Molecular Plant Physiology, D–14476 Potsdam-Golm, Germany (A.N.-N., A.R.F.)
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Abstract
A novel PhosphorImager-based technique which can be used to quantify low concentrations of radionuclides is described. The technique offers several benefits, combining very high sensitivity with containment of the radioisotope in the solid state, thus minimizing disposal procedures. In this study, it was used in conjunction with paper chromatography to quantify different oxidation states of (sup99)Tc in solution. The technique was used to evaluate the potential of anaerobic cultures of Shewanella putrefaciens and Geobacter metallireducens (bacteria with known metal-reducing capabilities) to reduce highly soluble Tc(VII) to insoluble lower-valence species, facilitating its removal from solution. Both organisms reduced Tc(VII), but profiles of Tc species produced in culture supernatants were strain specific. S. putrefaciens produced Tc(V), Tc(IV), and one unidentified species, but no Tc was removed from solution. G. metallireducens removed 70% of the 250 (mu)M Tc added in solution, with trace amounts of Tc(V) and the unidentified species detected in culture supernatants. Possible uses for these organisms in the bioremediation of Tc-contaminated waters are discussed, and other uses of the PhosphorImager technique are highlighted.
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Kötting O, Kossmann J, Zeeman SC, Lloyd JR. Regulation of starch metabolism: the age of enlightenment? Curr Opin Plant Biol 2010; 13:321-9. [PMID: 20171927 DOI: 10.1016/j.pbi.2010.01.003] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 01/21/2010] [Indexed: 05/04/2023]
Abstract
Starch and sucrose are the primary products of photosynthesis in the leaves of most plants. Starch represents the major plant storage carbohydrate providing energy during the times of heterotrophic growth. Starch metabolism has been studied extensively, leading to a good knowledge of the numerous enzymes involved. In contrast, understanding of the regulation of starch metabolism is fragmentary. This review summarises briefly the known steps in starch metabolism, highlighting recent discoveries. We also focus on evidence for potential regulatory mechanisms of the enzymes involved. These mechanisms include allosteric regulation by metabolites, redox regulation, protein-protein interactions and reversible protein phosphorylation. Modern systems biology and bioinformatic approaches are uncovering evidence for extensive post-translational protein modifications that may underlie enzyme regulation and identify novel proteins which may be involved in starch metabolism.
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Affiliation(s)
- Oliver Kötting
- Institute of Plant Sciences, ETH Zurich, Universitaetsstr. 2, CH-8092 Zurich, Switzerland.
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Héry M, Van Dongen BE, Gill F, Mondal D, Vaughan DJ, Pancost RD, Polya DA, Lloyd JR. Arsenic release and attenuation in low organic carbon aquifer sediments from West Bengal. Geobiology 2010; 8:155-168. [PMID: 20156294 DOI: 10.1111/j.1472-4669.2010.00233.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
High arsenic concentrations in groundwater are causing a humanitarian disaster in Southeast Asia. It is generally accepted that microbial activities play a critical role in the mobilization of arsenic from the sediments, with metal-reducing bacteria stimulated by organic carbon implicated. However, the detailed mechanisms underpinning these processes remain poorly understood. Of particular importance is the nature of the organic carbon driving the reduction of sorbed As(V) to the more mobile As(III), and the interplay between iron and sulphide minerals that can potentially immobilize both oxidation states of arsenic. Using a multidisciplinary approach, we identified the critical factors leading to arsenic release from West Bengal sediments. The results show that a cascade of redox processes was supported in the absence of high loadings of labile organic matter. Arsenic release was associated with As(V) and Fe(III) reduction, while the removal of arsenic was concomitant with sulphate reduction. The microbial populations potentially catalysing arsenic and sulphate reduction were identified by targeting the genes arrA and dsrB, and the total bacterial and archaeal communities by 16S rRNA gene analysis. Results suggest that very low concentrations of organic matter are able to support microbial arsenic mobilization via metal reduction, and subsequent arsenic mitigation through sulphate reduction. It may therefore be possible to enhance sulphate reduction through subtle manipulations to the carbon loading in such aquifers, to minimize the concentrations of arsenic in groundwaters.
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Affiliation(s)
- M Héry
- Williamson Research Centre for Molecular Environmental Science, University of Manchester, UK
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Rowland HAL, Boothman C, Pancost R, Gault AG, Polya DA, Lloyd JR. The role of indigenous microorganisms in the biodegradation of naturally occurring petroleum, the reduction of iron, and the mobilization of arsenite from west bengal aquifer sediments. J Environ Qual 2009; 38:1598-1607. [PMID: 19549936 DOI: 10.2134/jeq2008.0223] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
High levels of naturally occurring arsenic are found in the shallow reducing aquifers of West Bengal, Bangladesh, and other areas of Southeast Asia. These aquifers are used extensively for drinking water and irrigation by the local population. Mechanisms for its release are unclear, although increasing evidence points to a microbial control. The type of organic matter present is of vital importance because it has a direct impact on the rate of microbial activity and on the amount of arsenic released into the ground water. The discovery of naturally occurring hydrocarbons in an arsenic-rich aquifer from West Bengal provides a source of potential electron donors for this process. Using microcosm-based techniques, seven sediments from a site containing naturally occurring hydrocarbons in West Bengal were incubated with synthetic ground water for 28 d under anaerobic conditions without the addition of an external electron donor. Arsenic release and Fe(III) reduction appeared to be microbially mediated, with variable rates of arsenic mobilization in comparison to Fe(III) reduction, suggesting that multiple processes are involved. All sediments showed a preferential loss of petroleum-sourced n-alkanes over terrestrially sourced sedimentary hydrocarbons n-alkanes during the incubation, implying that the use of petroleum-sourced n-alkanes could support, directly or indirectly, microbial Fe(III) reduction. Samples undergoing maximal release of As(III) contained a significant population of Sulfurospirillum sp., a known As(V)-reducing bacterium, providing the first evidence that such organisms may mediate arsenic release from West Bengali aquifers.
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Affiliation(s)
- H A L Rowland
- School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The Univ. of Manchester, M13 9PL, UK
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35
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Ferreira SJ, Kossmann J, Lloyd JR, Groenewald JH. The reduction of starch accumulation in transgenic sugarcane cell suspension culture lines. Biotechnol J 2008; 3:1398-406. [DOI: 10.1002/biot.200800106] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lloyd JR, Pearce CI, Coker VS, Pattrick RAD, van der Laan G, Cutting R, Vaughan DJ, Paterson-Beedle M, Mikheenko IP, Yong P, Macaskie LE. Biomineralization: linking the fossil record to the production of high value functional materials. Geobiology 2008; 6:285-297. [PMID: 18462384 DOI: 10.1111/j.1472-4669.2008.00162.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The microbial cell offers a highly efficient template for the formation of nanoparticles with interesting properties including high catalytic, magnetic and light-emitting activities. Thus biomineralization products are not only important in global biogeochemical cycles, but they also have considerable commercial potential, offering new methods for material synthesis that eliminate toxic organic solvents and minimize expensive high-temperature and pressure processing steps. In this review we describe a range of bacterial processes that can be harnessed to make precious metal catalysts from waste streams, ferrite spinels for biomedicine and catalysis, metal phosphates for environmental remediation and biomedical applications, and biogenic selenides for a range of optical devices. Recent molecular-scale studies have shown that the structure and properties of bionanominerals can be fine-tuned by subtle manipulations to the starting materials and to the genetic makeup of the cell. This review is dedicated to the late Terry Beveridge who contributed much to the field of biomineralization, and provided early models to rationalize the mechanisms of biomineral synthesis, including those of geological and commercial potential.
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Affiliation(s)
- J R Lloyd
- School of Earth, Atmospheric and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Manchester M13 9PL, UK.
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37
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Pederick RL, Gault AG, Charnock JM, Polya DA, Lloyd JR. Probing the biogeochemistry of arsenic: response of two contrasting aquifer sediments from Cambodia to stimulation by arsenate and ferric iron. J Environ Sci Health A Tox Hazard Subst Environ Eng 2007; 42:1763-1774. [PMID: 17952777 DOI: 10.1080/10934520701564269] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Many millions of people worldwide are at risk of severe poisoning through exposure to groundwater contaminated with sediment-derived arsenic. An ever-increasing body of work is reinforcing the link between microbially-mediated redox cycling in aquifer sediments and the mobilisation of sorbed As(V) into groundwaters as the potentially more mobile and toxic As(III) anion. However, to date, few studies have examined the biogeochemical cycling of Fe and As species by microbes indigenous to Cambodian sediments. In this study two contrasting sediments, taken from a shallow As-rich reducing aquifer in the Kien Svay district of Cambodia, were used in a laboratory microcosm study. We present evidence to show that microbes present in these sediments are able to reduce Fe(III) and As(V) when provided with an electron donor, and that the two sediments respond differently to stimulation with Fe(III) and As(V). Shifts in the community composition of the two sediments after stimulation with As(V) suggest a potential role for members of the beta-Proteobacteria in As(V) reduction, a phylogenetic grouping known to contain microorganisms capable of As(III) oxidation, but not previously implicated in As(V) reduction. PCR-based analysis of the sediment microbial DNA using primers specific to the arrA gene, (a gene essential for microbial As(V) respiration), indicates the presence of microorganisms capable of dissimilatory As(V) reduction.
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Affiliation(s)
- R L Pederick
- School of Earth, Atmospheric and Environmental Sciences & Williamson Research Centre for Molecular Environmental Science, University of Manchester, UK
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38
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Ahmed MF, Ahuja S, Alauddin M, Hug SJ, Lloyd JR, Pfaff A, Pichler T, Saltikov C, Stute M, van Geen A. Epidemiology. Ensuring safe drinking water in Bangladesh. Science 2006; 314:1687-8. [PMID: 17170279 DOI: 10.1126/science.1133146] [Citation(s) in RCA: 206] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- M F Ahmed
- Bangladesh University of Engineering and Technology, Dhaka -1000, Bangladesh
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Coker VS, Gault AG, Pearce CI, van der Laan G, Telling ND, Charnock JM, Polya DA, Lloyd JR. XAS and XMCD evidence for species-dependent partitioning of arsenic during microbial reduction of ferrihydrite to magnetite. Environ Sci Technol 2006; 40:7745-50. [PMID: 17256522 DOI: 10.1021/es060990+] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Poorly crystalline Fe(III) oxyhydroxides, ubiquitously distributed as mineral coatings and discrete particles in aquifer sediments, are well-known hosts of sedimentary As. Microbial reduction of these phases is widely thought to be responsible for the genesis of As-rich reducing groundwaters found in many parts of the world, most notably in Bangladesh and West Bengal, India. As such, it is important to understand the behavior of As associated with ferric oxyhydroxides during the early stages of Fe(lll) reduction. We have used X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) to elucidate the changes in the bonding mechanism of As(III) and As(V) as their host Fe(III) oxyhydroxide undergoes bacterially induced reductive transformation to magnetite. Two-line ferrihydrite, with adsorbed As(III) or As(V), was incubated under anaerobic conditions in the presence of acetate as an electron donor, and Geobacter sulfurreducens, a subsurface bacterium capable of respiring on Fe(lll), but not As(V). In both experiments, no increase in dissolved As was observed during reduction to magnetite (complete upon 5 days incubation), consistent with our earlier observation of As sequestration by the formation of biogenic Fe(III)-bearing minerals. XAS data suggested that the As bonding environment of the As(III)-magnetite product is indistinguishable from that obtained from simple adsorption of As(lll) on the surface of biogenic magnetite. In contrast, reduction of As(V)-sorbed ferrihydrite to magnetite caused incorporation of As5+ within the magnetite structure. XMCD analysis provided further evidence of structural partitioning of As5+ as the small size of the As5+ cation caused a distortion of the spinel structure compared to standard biogenic magnetite. These results may have implications regarding the species-dependent mobility of As undergoing anoxic biogeochemical transformations, e.g., during early sedimentary diagenesis.
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Affiliation(s)
- V S Coker
- School of Earth, Atmospheric & Environmental Sciences & Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK
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Lear G, Song B, Gault AG, Polya DA, Lloyd JR. Molecular analysis of arsenate-reducing bacteria within Cambodian sediments following amendment with acetate. Appl Environ Microbiol 2006; 73:1041-8. [PMID: 17114326 PMCID: PMC1828664 DOI: 10.1128/aem.01654-06] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The health of millions is threatened by the use of groundwater contaminated with sediment-derived arsenic for drinking water and irrigation purposes in Southeast Asia. The microbial reduction of sorbed As(V) to the potentially more mobile As(III) has been implicated in release of arsenic into groundwater, but to date there have been few studies of the microorganisms that can mediate this transformation in aquifers. With the use of stable isotope probing of nucleic acids, we present evidence that the introduction of a proxy for organic matter ((13)C-labeled acetate) stimulated As(V) reduction in sediments collected from a Cambodian aquifer that hosts arsenic-rich groundwater. This was accompanied by an increase in the proportion of prokaryotes closely related to the dissimilatory As(V)-reducing bacteria Sulfurospirillum strain NP-4 and Desulfotomaculum auripigmentum. As(V) respiratory reductase genes (arrA) closely associated with those found in Sulfurospirillum barnesii and Geobacter uraniumreducens were also detected in active bacterial communities utilizing (13)C-labeled acetate in microcosms. This study suggests a direct link between inputs of organic matter and the increased prevalence and activity of organisms which transform As(V) to the potentially more mobile and thus hazardous As(III) via dissimilatory As(V) reduction.
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Affiliation(s)
- G Lear
- Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester M13 9PL, UK
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Boothman C, Hockin S, Holmes DE, Gadd GM, Lloyd JR. Molecular analysis of a sulphate-reducing consortium used to treat metal-containing effluents. Biometals 2006; 19:601-9. [PMID: 16946985 DOI: 10.1007/s10534-006-0006-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Accepted: 02/02/2006] [Indexed: 10/24/2022]
Abstract
A sulphate-reducing consortium used in a bioprocess to remove toxic metals from solution as insoluble sulphides, was characterised using molecular (PCR-based) and traditional culturing techniques. After prolonged cultivation under anoxic biofilm-forming conditions, the mixed culture contained a low diversity of sulphate-reducing bacteria, dominated by one strain closely related to Desulfomicrobium norvegicum, identified by three independent PCR-based analyses. The genetic targets used were the 16S rRNA gene, the 16S-23S rRNA gene intergenic spacer region and the disulfite reductase (dsr) gene, which is conserved amongst all known sulphate-reducing bacteria. This organism was also isolated by conventional anaerobic techniques, confirming its presence in the mixed culture. A surprising diversity of other non-sulphate-reducing facultative and obligate anaerobes were detected, supporting a model of the symbiotic/commensal nature of carbon and energy fluxes in such a mixed culture while suggesting the physiological capacity for a wide range of biotransformations by this stable microbial consortium.
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Affiliation(s)
- C Boothman
- School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester , UK
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42
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Islam FS, Pederick RL, Gault AG, Adams LK, Polya DA, Charnock JM, Lloyd JR. Interactions between the Fe(III)-reducing bacterium Geobacter sulfurreducens and arsenate, and capture of the metalloid by biogenic Fe(II). Appl Environ Microbiol 2006; 71:8642-8. [PMID: 16332858 PMCID: PMC1317334 DOI: 10.1128/aem.71.12.8642-8648.2005] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous work has shown that microbial communities in As-mobilizing sediments from West Bengal were dominated by Geobacter species. Thus, the potential of Geobacter sulfurreducens to mobilize arsenic via direct enzymatic reduction and indirect mechanisms linked to Fe(III) reduction was analyzed. G. sulfurreducens was unable to conserve energy for growth via the dissimilatory reduction of As(V), although it was able to grow in medium containing fumarate as the terminal electron acceptor in the presence of 500 muM As(V). There was also no evidence of As(III) in culture supernatants, suggesting that resistance to 500 muM As(V) was not mediated by a classical arsenic resistance operon, which would rely on the intracellular reduction of As(V) and the efflux of As(III). When the cells were grown using soluble Fe(III) as an electron acceptor in the presence of As(V), the Fe(II)-bearing mineral vivianite was formed. This was accompanied by the removal of As, predominantly as As(V), from solution. Biogenic siderite (ferrous carbonate) was also able to remove As from solution. When the organism was grown using insoluble ferrihydrite as an electron acceptor, Fe(III) reduction resulted in the formation of magnetite, again accompanied by the nearly quantitative sorption of As(V). These results demonstrate that G. sulfurreducens, a model Fe(III)-reducing bacterium, did not reduce As(V) enzymatically, despite the apparent genetic potential to mediate this transformation. However, the reduction of Fe(III) led to the formation of Fe(II)-bearing phases that are able to capture arsenic species and could act as sinks for arsenic in sediments.
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Affiliation(s)
- F S Islam
- School of Earth, Atmospheric and Environmental Sciences & Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, United Kingdom
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43
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Khijniak TV, Slobodkin AI, Coker V, Renshaw JC, Livens FR, Bonch-Osmolovskaya EA, Birkeland NK, Medvedeva-Lyalikova NN, Lloyd JR. Reduction of uranium(VI) phosphate during growth of the thermophilic bacterium Thermoterrabacterium ferrireducens. Appl Environ Microbiol 2005; 71:6423-6. [PMID: 16204572 PMCID: PMC1265970 DOI: 10.1128/aem.71.10.6423-6426.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The thermophilic, gram-positive bacterium Thermoterrabacterium ferrireducens coupled organotrophic growth to the reduction of sparingly soluble U(VI) phosphate. X-ray powder diffraction and X-ray absorption spectroscopy analysis identified the electron acceptor in a defined medium as U(VI) phosphate [uramphite; (NH4)(UO2)(PO4) . 3H2O], while the U(IV)-containing precipitate formed during bacterial growth was identified as ningyoite [CaU(PO4)2 . H2O]. This is the first report of microbial reduction of a largely insoluble U(VI) compound.
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Affiliation(s)
- T V Khijniak
- The Williamson Research Centre for Molecular Environmental Science and The School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
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Abstract
During the day, plants accumulate starch in their leaves as an energy source for the coming night. Based on recent findings, the prevailing view of how the transitory starch is remobilized needs considerable revision. Analyses of transgenic and mutant plants demonstrate that plastidic glucan phosphorylase is not required for normal starch breakdown and cast doubt on the presumed essential role of alpha-amylase but do show that beta-amylase is important. Repression of the activity of a plastidic beta-amylase, the export of its product (maltose) or further metabolism of maltose by a newly identified transglucosidase impairs starch degradation. Breakdown of particulate starch also depends on the activity of glucan-water dikinase, which phosphorylates glucosyl residues within the polymer.
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Affiliation(s)
- James R Lloyd
- Institute of Plant Biotechnology, University of Stellenbosch, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa.
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Obiadalla-Ali H, Fernie AR, Lytovchenko A, Kossmann J, Lloyd JR. Inhibition of chloroplastic fructose 1,6-bisphosphatase in tomato fruits leads to decreased fruit size, but only small changes in carbohydrate metabolism. Planta 2004; 219:533-40. [PMID: 15060828 DOI: 10.1007/s00425-004-1257-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2003] [Accepted: 02/03/2004] [Indexed: 05/06/2023]
Abstract
A potato (Solanum tuberosum L.) cDNA coding for the chloroplastic isoform of fructose 1,6-bisphosphatase (cp-FBPase) was utilized to repress its activity in tomatoes (Lycopersicon esculentum Mill.) using antisense techniques. The patatin B33 promoter was used to ensure fruit specificity of the antisense effect. Transgenic plants were isolated in which fructose 1,6-bisphosphatase activity was reduced by more than 50% of the control in green fruits. Immunoblots indicated that the plastidial isoform was almost completely eliminated in the most strongly inhibited lines. Fruits of the transgenic plants were analyzed for levels of metabolites during fruit development. Glucose and fructose concentrations were increased in green fruits in the transgenic lines, but unchanged at later stages of development. The sucrose concentration was low, and was not significantly altered in the transgenic lines. There was net degradation of starch over the developmental period, but the starch content was not decreased. In green fruit the levels of hexose phosphates were unchanged, whilst the level of 3-phosphoglyceric acid was significantly increased in one line. Most importantly the deduced ratio of hexose phosphate to 3-phosphoglyceric acid decreased, consistent with an in vivo inhibition of fructose 1,6-bisphosphatase activity. One consequence of this reduction of in vivo activity of cp-FBPase was that the average weight of fully ripe fruits was significantly decreased by up to 20% in all transgenic lines in comparison with the control.
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Affiliation(s)
- Hazem Obiadalla-Ali
- Willmitzer Department, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Golm, Germany
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Schulze S, Mant A, Kossmann J, Lloyd JR. Identification of an Arabidopsis inorganic pyrophosphatase capable of being imported into chloroplasts. FEBS Lett 2004; 565:101-5. [PMID: 15135060 DOI: 10.1016/j.febslet.2004.03.080] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Revised: 03/25/2004] [Accepted: 03/29/2004] [Indexed: 11/19/2022]
Abstract
An Arabidopsis cDNA coding for a previously uncharacterized isoform of inorganic pyrophosphatase was isolated. It was used to complement an E. coli mutant, demonstrating that it coded for an active enzyme. MgCl(2) was necessary for the protein's activity, whilst NaF inhibited it. The K(m) for pyrophosphate and the pH optimum of the protein was determined. The gene coding for this protein was expressed in all tissues, and its expression in rosette leaves was induced by incubation on metabolizable sugars. In vitro import experiments demonstrated that the protein could be imported into chloroplasts and localized to the stromal compartment.
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Affiliation(s)
- Silke Schulze
- Max-Planck-Institute of Molecular Plant Physiology, Golm, Germany
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Lloyd JR, Blennow A, Burhenne K, Kossmann J. Repression of a novel isoform of disproportionating enzyme (stDPE2) in potato leads to inhibition of starch degradation in leaves but not tubers stored at low temperature. Plant Physiol 2004; 134:1347-54. [PMID: 15034166 PMCID: PMC419812 DOI: 10.1104/pp.103.038026] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Revised: 01/20/2004] [Accepted: 01/26/2004] [Indexed: 05/17/2023]
Abstract
A potato (Solanum tuberosum) cDNA encoding an isoform of disproportionating enzyme (stDPE2) was identified in a functional screen in Escherichia coli. The stDPE2 protein was demonstrated to be present in chloroplasts and to accumulate at times of active starch degradation in potato leaves and tubers. Transgenic potato plants were made in which its presence was almost completely eliminated. It could be demonstrated that starch degradation was repressed in leaves of the transgenic plants but that cold-induced sweetening was not affected in tubers stored at 4 degrees C. No evidence could be found for an effect of repression of stDPE2 on starch synthesis. The malto-oligosaccharide content of leaves from the transgenic plants was assessed. It was found that the amounts of malto-oligosaccharides increased in all plants during the dark period and that the transgenic lines accumulated up to 10-fold more than the control. Separation of these malto-oligosaccharides by high-performance anion-exchange chromatography with pulsed-amperometric detection showed that the only one that accumulated in the transgenic plants in comparison with the control was maltose. stDPE2 was purified to apparent homogeneity from potato tuber extracts and could be demonstrated to transfer glucose from maltose to oyster glycogen.
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Affiliation(s)
- James R Lloyd
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Golm, Germany
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Lloyd JR, Klessa DA, Parry DL, Buck P, Brown NL. Stimulation of microbial sulphate reduction in a constructed wetland: microbiological and geochemical analysis. Water Res 2004; 38:1822-1830. [PMID: 15026237 DOI: 10.1016/j.watres.2003.12.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2002] [Revised: 09/15/2003] [Accepted: 12/18/2003] [Indexed: 05/24/2023]
Abstract
Microbial sulphate reduction was stimulated successfully in enclosures installed in a constructed wetland. When sucrose (2.4mM) and NH(4)Cl (600 microM) were added to water in the test enclosures, the indigenous microbial community was able to remove over 90% of the sulphate, present as a contaminant from nearby mining activity at a concentration of 384 mg x l(-1) (4mM), over 50 days. Over 90% of the sucrose was also removed. Sulphate was not reduced in control enclosures containing no added sucrose or NH(4)Cl. Fermentation of sucrose by obligate anaerobes including Clostridium sp. and Bacteriodes sp. preceded sulphate reduction in the test enclosures. Sulphate reduction was biphasic, with maximum rates noted between 2-5 and 23-27 days after the addition of the growth substrates. Relatively unbiased 16S rDNA analysis suggested that nitrogen-fixing bacteria were important constituents of the microbial community in the test enclosures at day 23, suggesting that soluble nitrogen was limiting in the amended test enclosures during the experiment.
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Affiliation(s)
- J R Lloyd
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
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Obiadalla-Ali H, Fernie AR, Kossmann J, Lloyd JR. Developmental analysis of carbohydrate metabolism in tomato (Lycopersicon esculentum cv. Micro-Tom) fruits. Physiol Plant 2004; 120:196-204. [PMID: 15032853 DOI: 10.1111/j.0031-9317.2004.0167.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Carbohydrate metabolism during the development of fruits of the tomato cultivar Micro-Tom was studied. The metabolism of the pericarp and placental tissues was found to be different. Starch was degraded more slowly in the placenta in comparison with the pericarp, whereas soluble sugars accumulated to a greater extent in the pericarp. The activities of glycolytic enzymes tended to peak at 40 days after flowering. Two of these, phosphoenolpyruvate phosphatase and pyruvate kinase, showed a dramatic increase in activity just before this peak, possibly indicating a role in up-regulating glycolysis to generate increased ATP that would be used during climacteric respiration. The expression of plastidial transporters was studied. Both the TPT and Glu6P transporter were expressed greatest in green fruits, before declining. The expression of the triose-phosphate transporter was greater than that of the glucose 6-phosphate transporter. The ATP/ADP transporter was expressed to a low level throughout fruit development.
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Affiliation(s)
- Hazem Obiadalla-Ali
- Max Planck Institute of Molecular Plant Physiology, Willmitzer Department, Am Mühlenberg 1, D-14476 Golm, Germany
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Ritte G, Steup M, Kossmann J, Lloyd JR. Determination of the starch-phosphorylating enzyme activity in plant extracts. Planta 2003; 216:798-801. [PMID: 12624767 DOI: 10.1007/s00425-002-0931-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Accepted: 09/07/2002] [Indexed: 05/24/2023]
Abstract
For quantification of alpha-glucan, water dikinase (GWD) activity in crude extracts of plant tissues a radio-labeling assay was established that uses soluble starch and (33)P-labeled ATP as phosphate acceptor and donor, respectively. A constant rate of starch labeling was observed only if the ATP applied was labeled at the beta position. In wild-type extracts from leaves of Arabidopsis thaliana (L.) Heynh. the maximum rate of starch phosphorylation was approximately 27 pmol min(-1) (mg protein)(-1). Leaf extracts from the GWD-deficient sex1 mutants of Arabidopsis showed no significant incorporation of phosphate whereas extracts from potato (Solanum tuberosum L.) tuber expressing a GWD antisense construct exhibited less activity than the wild-type control. To our knowledge this is the first time that a quantification of the starch-phosphorylating activity has been achieved in plant crude extracts.
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Affiliation(s)
- Gerhard Ritte
- Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25 Haus 20, 14476 Golm, Germany
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