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Sample records for higher plant glycosyltransferases

  1. Heterologous expression of plant cell wall glycosyltransferases in Pichia, pea and tobacco

    DEFF Research Database (Denmark)

    Petersen, Bent Larsen; Damager, Iben; Faber, Kirsten

    The plant cell wall (CW) consists of numerous complex and uniqe carbohydrate polymer structures. Although the structure (sugar composition) of the various plant CW components are known in some detail, functional characterisation of of the more than 300 glycosyltransferases (GTs), that are believed...... to participate in plant CW biosynthesis, has been achieved in only a few cases. We have previously reported the characterisation of two highly homologous plant-specific membrane-bound GTs, which when expressed as secreted tagged soluble proteins in the baculo virus system, catalysed the transfer of xylose from...... UDP-xylose on to the monosaccharide sugar fucose. Partly based on these data, the two genes were proposed to function in the biosynthesis of pectic rhamnogalacturonan II (RG-II) and designated RhamnoGalacturonan XylosylTransferase 1 and -2 (RGXT1 and -2), accordingly (Egelund et al. 2006, The Plant...

  2. Plant cell wall glycosyltransferases: High-throughput recombinant expression screening and general requirements for these challenging enzymes.

    Directory of Open Access Journals (Sweden)

    Ditte Hededam Welner

    Full Text Available Molecular characterization of plant cell wall glycosyltransferases is a critical step towards understanding the biosynthesis of the complex plant cell wall, and ultimately for efficient engineering of biofuel and agricultural crops. The majority of these enzymes have proven very difficult to obtain in the needed amount and purity for such molecular studies, and recombinant cell wall glycosyltransferase production efforts have largely failed. A daunting number of strategies can be employed to overcome this challenge, including optimization of DNA and protein sequences, choice of expression organism, expression conditions, co-expression partners, purification methods, and optimization of protein solubility and stability. Hence researchers are presented with thousands of potential conditions to test. Ultimately, the subset of conditions that will be sampled depends on practical considerations and prior knowledge of the enzyme(s being studied. We have developed a rational approach to this process. We devise a pipeline comprising in silico selection of targets and construct design, and high-throughput expression screening, target enrichment, and hit identification. We have applied this pipeline to a test set of Arabidopsis thaliana cell wall glycosyltransferases known to be challenging to obtain in soluble form, as well as to a library of cell wall glycosyltransferases from other plants including agricultural and biofuel crops. The screening results suggest that recombinant cell wall glycosyltransferases in general have a very low soluble:insoluble ratio in lysates from heterologous expression cultures, and that co-expression of chaperones as well as lysis buffer optimization can increase this ratio. We have applied the identified preferred conditions to Reversibly Glycosylated Polypeptide 1 from Arabidopsis thaliana, and processed this enzyme to near-purity in unprecedented milligram amounts. The obtained preparation of Reversibly Glycosylated

  3. C-Glycosyltransferases catalyzing the formation of di-C-glucosyl flavonoids in citrus plants.

    Science.gov (United States)

    Ito, Takamitsu; Fujimoto, Shunsuke; Suito, Fumiaki; Shimosaka, Makoto; Taguchi, Goro

    2017-07-01

    Citrus plants accumulate many kinds of flavonoids, including di-C-glucosyl flavonoids, which have attracted considerable attention due to their health benefits. However, the biosynthesis of di-C-glucosyl flavonoids has not been elucidated at the molecular level. Here, we identified the C-glycosyltransferases (CGTs) FcCGT (UGT708G1) and CuCGT (UGT708G2) as the primary enzymes involved in the biosynthesis of di-C-glucosyl flavonoids in the citrus plants kumquat (Fortunella crassifolia) and satsuma mandarin (Citrus unshiu), respectively. The amino acid sequences of these CGTs were 98% identical, indicating that CGT genes are highly conserved in the citrus family. The recombinant enzymes FcCGT and CuCGT utilized 2-hydroxyflavanones, dihydrochalcone, and their mono-C-glucosides as sugar acceptors and produced corresponding di-C-glucosides. The Km and kcat values of FcCGT toward phloretin were flavonoid biosynthesis proceeds via a single enzyme using either 2-hydroxyflavanones or phloretin as a substrate in citrus plants. In addition, Escherichia coli cells expressing CGT genes were found to be capable of producing di-C-glucosyl flavonoids, which is promising for commercial production of these valuable compounds. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  4. A conserved fungal glycosyltransferase facilitates pathogenesis of plants by enabling hyphal growth on solid surfaces.

    Science.gov (United States)

    King, Robert; Urban, Martin; Lauder, Rebecca P; Hawkins, Nichola; Evans, Matthew; Plummer, Amy; Halsey, Kirstie; Lovegrove, Alison; Hammond-Kosack, Kim; Rudd, Jason J

    2017-10-01

    Pathogenic fungi must extend filamentous hyphae across solid surfaces to cause diseases of plants. However, the full inventory of genes which support this is incomplete and many may be currently concealed due to their essentiality for the hyphal growth form. During a random T-DNA mutagenesis screen performed on the pleomorphic wheat (Triticum aestivum) pathogen Zymoseptoria tritici, we acquired a mutant unable to extend hyphae specifically when on solid surfaces. In contrast "yeast-like" growth, and all other growth forms, were unaffected. The inability to extend surface hyphae resulted in a complete loss of virulence on plants. The affected gene encoded a predicted type 2 glycosyltransferase (ZtGT2). Analysis of >800 genomes from taxonomically diverse fungi highlighted a generally widespread, but discontinuous, distribution of ZtGT2 orthologues, and a complete absence of any similar proteins in non-filamentous ascomycete yeasts. Deletion mutants of the ZtGT2 orthologue in the taxonomically un-related fungus Fusarium graminearum were also severely impaired in hyphal growth and non-pathogenic on wheat ears. ZtGT2 expression increased during filamentous growth and electron microscopy on deletion mutants (ΔZtGT2) suggested the protein functions to maintain the outermost surface of the fungal cell wall. Despite this, adhesion to leaf surfaces was unaffected in ΔZtGT2 mutants and global RNAseq-based gene expression profiling highlighted that surface-sensing and protein secretion was also largely unaffected. However, ΔZtGT2 mutants constitutively overexpressed several transmembrane and secreted proteins, including an important LysM-domain chitin-binding virulence effector, Zt3LysM. ZtGT2 likely functions in the synthesis of a currently unknown, potentially minor but widespread, extracellular or outer cell wall polysaccharide which plays a key role in facilitating many interactions between plants and fungi by enabling hyphal growth on solid matrices.

  5. A conserved fungal glycosyltransferase facilitates pathogenesis of plants by enabling hyphal growth on solid surfaces.

    Directory of Open Access Journals (Sweden)

    Robert King

    2017-10-01

    Full Text Available Pathogenic fungi must extend filamentous hyphae across solid surfaces to cause diseases of plants. However, the full inventory of genes which support this is incomplete and many may be currently concealed due to their essentiality for the hyphal growth form. During a random T-DNA mutagenesis screen performed on the pleomorphic wheat (Triticum aestivum pathogen Zymoseptoria tritici, we acquired a mutant unable to extend hyphae specifically when on solid surfaces. In contrast "yeast-like" growth, and all other growth forms, were unaffected. The inability to extend surface hyphae resulted in a complete loss of virulence on plants. The affected gene encoded a predicted type 2 glycosyltransferase (ZtGT2. Analysis of >800 genomes from taxonomically diverse fungi highlighted a generally widespread, but discontinuous, distribution of ZtGT2 orthologues, and a complete absence of any similar proteins in non-filamentous ascomycete yeasts. Deletion mutants of the ZtGT2 orthologue in the taxonomically un-related fungus Fusarium graminearum were also severely impaired in hyphal growth and non-pathogenic on wheat ears. ZtGT2 expression increased during filamentous growth and electron microscopy on deletion mutants (ΔZtGT2 suggested the protein functions to maintain the outermost surface of the fungal cell wall. Despite this, adhesion to leaf surfaces was unaffected in ΔZtGT2 mutants and global RNAseq-based gene expression profiling highlighted that surface-sensing and protein secretion was also largely unaffected. However, ΔZtGT2 mutants constitutively overexpressed several transmembrane and secreted proteins, including an important LysM-domain chitin-binding virulence effector, Zt3LysM. ZtGT2 likely functions in the synthesis of a currently unknown, potentially minor but widespread, extracellular or outer cell wall polysaccharide which plays a key role in facilitating many interactions between plants and fungi by enabling hyphal growth on solid matrices.

  6. Putative glycosyltransferases and other plant Golgi apparatus proteins are revealed by LOPIT proteomics.

    Science.gov (United States)

    Nikolovski, Nino; Rubtsov, Denis; Segura, Marcelo P; Miles, Godfrey P; Stevens, Tim J; Dunkley, Tom P J; Munro, Sean; Lilley, Kathryn S; Dupree, Paul

    2012-10-01

    The Golgi apparatus is the central organelle in the secretory pathway and plays key roles in glycosylation, protein sorting, and secretion in plants. Enzymes involved in the biosynthesis of complex polysaccharides, glycoproteins, and glycolipids are located in this organelle, but the majority of them remain uncharacterized. Here, we studied the Arabidopsis (Arabidopsis thaliana) membrane proteome with a focus on the Golgi apparatus using localization of organelle proteins by isotope tagging. By applying multivariate data analysis to a combined data set of two new and two previously published localization of organelle proteins by isotope tagging experiments, we identified the subcellular localization of 1,110 proteins with high confidence. These include 197 Golgi apparatus proteins, 79 of which have not been localized previously by a high-confidence method, as well as the localization of 304 endoplasmic reticulum and 208 plasma membrane proteins. Comparison of the hydrophobic domains of the localized proteins showed that the single-span transmembrane domains have unique properties in each organelle. Many of the novel Golgi-localized proteins belong to uncharacterized protein families. Structure-based homology analysis identified 12 putative Golgi glycosyltransferase (GT) families that have no functionally characterized members and, therefore, are not yet assigned to a Carbohydrate-Active Enzymes database GT family. The substantial numbers of these putative GTs lead us to estimate that the true number of plant Golgi GTs might be one-third above those currently annotated. Other newly identified proteins are likely to be involved in the transport and interconversion of nucleotide sugar substrates as well as polysaccharide and protein modification.

  7. Arabinogalactan glycosyltransferases target to a unique subcellular compartment that may function in unconventional secretion in plants

    DEFF Research Database (Denmark)

    Poulsen, Christian Peter; Dilokpimol, Adiphol; Mouille, Grégory

    2014-01-01

    We report that fluorescently tagged arabinogalactan glycosyltransferases target not only the Golgi apparatus but also uncharacterized smaller compartments when transiently expressed in Nicotiana benthamiana. Approximately 80% of AtGALT31A [Arabidopsis thaliana galactosyltransferase from family 31......-glycosylation enzymes rarely colocalized (3-18%), implicating a role of the small compartments in a part of arabinogalactan (O-glycan) biosynthesis rather than N-glycan processing. The dual localization of AtGALT31A was also observed for fluorescently tagged AtGALT31A stably expressed in an Arabidopsis atgalt31a mutant...

  8. Cotton GalT1 encoding a putative glycosyltransferase is involved in regulation of cell wall pectin biosynthesis during plant development.

    Directory of Open Access Journals (Sweden)

    Li-Xia Qin

    Full Text Available Arabinogalactan proteins (AGPs, are a group of highly glycosylated proteins that are found throughout the plant kingdom. To date, glycosyltransferases that glycosylate AGP backbone have remained largely unknown. In this study, a gene (GhGalT1 encoding a putative β-1,3-galactosyltransferase (GalT was identified in cotton. GhGalT1, belonging to CAZy GT31 family, is the type II membrane protein that contains an N-terminal transmembrane domain and a C-terminal galactosyltransferase functional domain. A subcellular localization assay demonstrated that GhGalT1 was localized in the Golgi apparatus. RT-PCR analysis revealed that GhGalT1 was expressed at relatively high levels in hypocotyls, roots, fibers and ovules. Overexpression of GhGalT1 in Arabidopsis promoted plant growth and metabolism. The transgenic seedlings had much longer primary roots, higher chlorophyll content, higher photosynthetic efficiency, the increased biomass, and the enhanced tolerance to exogenous D-arabinose and D-galactose. In addition, gas chromatography (GC analysis of monosaccharide composition of cell wall fractions showed that pectin was changed in the transgenic plants, compared with that of wild type. Three genes (GAUT8, GAUT9 and xgd1 involved in pectin biosynthesis were dramatically up-regulated in the transgenic lines. These data suggested that GhGalT1 may be involved in regulation of pectin biosynthesis required for plant development.

  9. Assay and heterologous expression in Pichia pastoris of plant cell wall type-II membrane anchored glycosyltransferases

    DEFF Research Database (Denmark)

    Petersen, Bent Larsen; Egelund, Jack; Damager, Iben

    2009-01-01

    Two Arabidopsis xylosyltransferases, designated RGXT1 and RGXT2, were recently expressed in Baculovirus transfected insect cells and by use of the free sugar assay shown to catalyse transfer of D-xylose from UDP-α-D-xylose to L-fucose and derivatives hereof. We have now examined expression of RGX...... nmol conversion of substrate • min-1 • µl medium-1) similar to those of RGXT1 and RGXT2 expressed in Baculovirus transfected insect Sf9 cells. In summary, the data presented suggest that Pichia is an attractive host candidate for expression of plant glycosyltransferases.......Two Arabidopsis xylosyltransferases, designated RGXT1 and RGXT2, were recently expressed in Baculovirus transfected insect cells and by use of the free sugar assay shown to catalyse transfer of D-xylose from UDP-α-D-xylose to L-fucose and derivatives hereof. We have now examined expression of RGXT1...

  10. Expression of Codon-Optimized Plant Glycosyltransferase UGT72B14 in Escherichia coli Enhances Salidroside Production

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    Feiyan Xue

    2016-01-01

    Full Text Available Salidroside, a plant secondary metabolite in Rhodiola, has been demonstrated to have several adaptogenic properties as a medicinal herb. Due to the limitation of plant source, microbial production of salidroside by expression of plant uridine diphosphate glycosyltransferase (UGT is promising. However, glycoside production usually remains hampered by poor expression of plant UGTs in microorganisms. Herein, we achieved salidroside production by expression of Rhodiola UGT72B14 in Escherichia coli (E. coli and codon optimization was accordingly applied. UGT72B14 expression was optimized by changing 278 nucleotides and decreasing the G+C content to 51.05% without altering the amino acid sequence. The effect of codon optimization on UGT72B14 catalysis for salidroside production was assessed both in vitro and in vivo. In vitro, salidroside production by codon-optimized UGT72B14 is enhanced because of a significantly improved protein yield (increased by 4.8-fold and an equivalently high activity as demonstrated by similar kinetic parameters (KM and Vmax, compared to that by wild-type protein. In vivo, both batch and fed-batch cultivation using the codon-optimized gene resulted in a significant increase in salidroside production, which was up to 6.7 mg/L increasing 3.2-fold over the wild-type UGT72B14.

  11. Expression of Codon-Optimized Plant Glycosyltransferase UGT72B14 in Escherichia coli Enhances Salidroside Production.

    Science.gov (United States)

    Xue, Feiyan; Guo, Huili; Hu, Yingying; Liu, Ran; Huang, Lina; Lv, Heshu; Liu, Chunmei; Yang, Mingfeng; Ma, Lanqing

    2016-01-01

    Salidroside, a plant secondary metabolite in Rhodiola, has been demonstrated to have several adaptogenic properties as a medicinal herb. Due to the limitation of plant source, microbial production of salidroside by expression of plant uridine diphosphate glycosyltransferase (UGT) is promising. However, glycoside production usually remains hampered by poor expression of plant UGTs in microorganisms. Herein, we achieved salidroside production by expression of Rhodiola UGT72B14 in Escherichia coli (E. coli) and codon optimization was accordingly applied. UGT72B14 expression was optimized by changing 278 nucleotides and decreasing the G+C content to 51.05% without altering the amino acid sequence. The effect of codon optimization on UGT72B14 catalysis for salidroside production was assessed both in vitro and in vivo. In vitro, salidroside production by codon-optimized UGT72B14 is enhanced because of a significantly improved protein yield (increased by 4.8-fold) and an equivalently high activity as demonstrated by similar kinetic parameters (K M and V max), compared to that by wild-type protein. In vivo, both batch and fed-batch cultivation using the codon-optimized gene resulted in a significant increase in salidroside production, which was up to 6.7 mg/L increasing 3.2-fold over the wild-type UGT72B14.

  12. Functional Analysis of an Uridine Diphosphate Glycosyltransferase Involved in the Biosynthesis of Polyphenolic Glucoside in Tea Plants (Camellia sinensis).

    Science.gov (United States)

    Zhao, Xuecheng; Dai, Xinlong; Gao, Liping; Guo, Lina; Zhuang, Juhua; Liu, Yajun; Ma, Xiubing; Wang, Rui; Xia, Tao; Wang, Yunsheng

    2017-12-20

    Polyphenols are one of the largest groups of compounds that confer benefits to the health of plants and humans. Flavonol glycosides are a major ingredient of polyphenols in Camellia sinensis. Flavonol-3-O-glycosides are characteristic astringent taste compounds in tea infusion. A polyphenolic glycosyltransferase (CsUGT72AM1) belonging to cluster IIIb was isolated from the tea plant. The full-length cDNA of CsUGT72AM1 is 1416 bp. It encodes 472 amino acids with a calculated molecular mass of 50.92 kDa and an isoelectric point of 5.21. The recombinant CsUGT72AM1 protein was expressed in Escherichia coli and exhibited catalytic activity toward multiple flavonoids and coniferyl aldehyde. The enzyme assay indicated that rCsUGT72AM1 could perform glycosidation of flavonols or coniferyl aldehyde in vitro to form 3-O-glucoside or 4-O-glucoside, respectively. Interestingly, this enzyme also had activities and performed multisite glycosidation toward flavanones. The consistent products were confirmed to be naringenin-7-O-glucoside and -4'-O-glucoside by the nuclear magnetism assay. In addition, in the enzyme assay with cyanidin as the substrate, the results suggested that the glycosylated activity of CsUGT72AM1 was remarkably inhibited by a high concentration of anthocyanins. The above results indicate that CsUGT72AM1 may be involved in the metabolism of flavonol, flavanone, anthocyanin, and lignin.

  13. Volatile Glycosylation in Tea Plants: Sequential Glycosylations for the Biosynthesis of Aroma β-Primeverosides Are Catalyzed by Two Camellia sinensis Glycosyltransferases1[OPEN

    Science.gov (United States)

    Ohgami, Shoji; Ono, Eiichiro; Horikawa, Manabu; Murata, Jun; Totsuka, Koujirou; Toyonaga, Hiromi; Ohba, Yukie; Dohra, Hideo; Asai, Tatsuo; Mizutani, Masaharu; Watanabe, Naoharu

    2015-01-01

    Tea plants (Camellia sinensis) store volatile organic compounds (VOCs; monoterpene, aromatic, and aliphatic alcohols) in the leaves in the form of water-soluble diglycosides, primarily as β-primeverosides (6-O-β-d-xylopyranosyl-β-d-glucopyranosides). These VOCs play a critical role in plant defenses and tea aroma quality, yet little is known about their biosynthesis and physiological roles in planta. Here, we identified two UDP-glycosyltransferases (UGTs) from C. sinensis, UGT85K11 (CsGT1) and UGT94P1 (CsGT2), converting VOCs into β-primeverosides by sequential glucosylation and xylosylation, respectively. CsGT1 exhibits a broad substrate specificity toward monoterpene, aromatic, and aliphatic alcohols to produce the respective glucosides. On the other hand, CsGT2 specifically catalyzes the xylosylation of the 6′-hydroxy group of the sugar moiety of geranyl β-d-glucopyranoside, producing geranyl β-primeveroside. Homology modeling, followed by site-directed mutagenesis of CsGT2, identified a unique isoleucine-141 residue playing a crucial role in sugar donor specificity toward UDP-xylose. The transcripts of both CsGTs were mainly expressed in young leaves, along with β-PRIMEVEROSIDASE encoding a diglycoside-specific glycosidase. In conclusion, our findings reveal the mechanism of aroma β-primeveroside biosynthesis in C. sinensis. This information can be used to preserve tea aroma better during the manufacturing process and to investigate the mechanism of plant chemical defenses. PMID:25922059

  14. Cellulose biosynthesis in higher plants

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    Krystyna Kudlicka

    2014-01-01

    Full Text Available Knowledge of the control and regulation of cellulose synthesis is fundamental to an understanding of plant development since cellulose is the primary structural component of plant cell walls. In vivo, the polymerization step requires a coordinated transport of substrates across membranes and relies on delicate orientations of the membrane-associated synthase complexes. Little is known about the properties of the enzyme complexes, and many questions about the biosynthesis of cell wall components at the cell surface still remain unanswered. Attempts to purify cellulose synthase from higher plants have not been successful because of the liability of enzymes upon isolation and lack of reliable in vitro assays. Membrane preparations from higher plant cells incorporate UDP-glucose into a glucan polymer, but this invariably turns out to be predominantly β -1,3-linked rather than β -1,4-linked glucans. Various hypotheses have been advanced to explain this phenomenon. One idea is that callose and cellulose-synthase systems are the same, but cell disruption activates callose synthesis preferentially. A second concept suggests that a regulatory protein as a part of the cellulose-synthase complex is rapidly degraded upon cell disruption. With new methods of enzyme isolation and analysis of the in vitro product, recent advances have been made in the isolation of an active synthase from the plasma membrane whereby cellulose synthase was separated from callose synthase.

  15. Chromosomal replicons of higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Van' t Hof, J.

    1987-03-16

    This brief discussion of replicons of higher plants offers a glimpse into the properties of chromosomal DNA replication. It gives evidence that the S phase of unrelated plant species is comprised of temporally ordered replicon families that increase in number with genome size. This orderly process, which assures a normal inheritance of genetic material to recipient daughter cells, is maintained at the level of replicon clusters by two mutually exclusive mechanisms, one involving the rate at which single replicons replicate their allotment of DNA, and another by means of the tempo-pause. The same two mechanisms are used by cells to alter the pattern of chromosomal DNA replication just prior to and during normal development. Both mechanisms are genetically determined and produce genetic effects when disturbed of disrupted by additional non-conforming DNAs. Further insight into how these two mechanisms operate requires more molecular information about the nature of replicons and the factors that govern when a replicon family replicates. Plant material is a rich and ideal source for this information just awaiting exploitation. 63 refs.

  16. Volatile Glycosylation in Tea Plants: Sequential Glycosylations for the Biosynthesis of Aroma β-Primeverosides Are Catalyzed by Two Camellia sinensis Glycosyltransferases.

    Science.gov (United States)

    Ohgami, Shoji; Ono, Eiichiro; Horikawa, Manabu; Murata, Jun; Totsuka, Koujirou; Toyonaga, Hiromi; Ohba, Yukie; Dohra, Hideo; Asai, Tatsuo; Matsui, Kenji; Mizutani, Masaharu; Watanabe, Naoharu; Ohnishi, Toshiyuki

    2015-06-01

    Tea plants (Camellia sinensis) store volatile organic compounds (VOCs; monoterpene, aromatic, and aliphatic alcohols) in the leaves in the form of water-soluble diglycosides, primarily as β-primeverosides (6-O-β-D-xylopyranosyl-β-D-glucopyranosides). These VOCs play a critical role in plant defenses and tea aroma quality, yet little is known about their biosynthesis and physiological roles in planta. Here, we identified two UDP-glycosyltransferases (UGTs) from C. sinensis, UGT85K11 (CsGT1) and UGT94P1 (CsGT2), converting VOCs into β-primeverosides by sequential glucosylation and xylosylation, respectively. CsGT1 exhibits a broad substrate specificity toward monoterpene, aromatic, and aliphatic alcohols to produce the respective glucosides. On the other hand, CsGT2 specifically catalyzes the xylosylation of the 6'-hydroxy group of the sugar moiety of geranyl β-D-glucopyranoside, producing geranyl β-primeveroside. Homology modeling, followed by site-directed mutagenesis of CsGT2, identified a unique isoleucine-141 residue playing a crucial role in sugar donor specificity toward UDP-xylose. The transcripts of both CsGTs were mainly expressed in young leaves, along with β-primeverosidase encoding a diglycoside-specific glycosidase. In conclusion, our findings reveal the mechanism of aroma β-primeveroside biosynthesis in C. sinensis. This information can be used to preserve tea aroma better during the manufacturing process and to investigate the mechanism of plant chemical defenses. © 2015 American Society of Plant Biologists. All Rights Reserved.

  17. Classical mutagenesis in higher plants

    NARCIS (Netherlands)

    Koornneef, M.

    2002-01-01

    For a long time, mutagenesis research in plants focused on crop improvement and, especially for crop plants, opimised protocols were developed with barley being one of the favourite species. However, the interest in mutagenesis has shifted to basic plant research in the last 20 years, when the power

  18. Classical mutagenesis in higher plants

    OpenAIRE

    Koornneef, M.

    2002-01-01

    For a long time, mutagenesis research in plants focused on crop improvement and, especially for crop plants, opimised protocols were developed with barley being one of the favourite species. However, the interest in mutagenesis has shifted to basic plant research in the last 20 years, when the power of mutant approaches in combination with molecular techniques to investigate the molecular nature of the genes became fully appreciated

  19. Silicon transporters in higher plants.

    Science.gov (United States)

    Ma, Jian Feng

    2010-01-01

    Silicon (Si) is the second most abundant element in the Earth's crust and exerts beneficial effects on plant growth and production by alleviating both biotic and abiotic stresses including diseases, pests, lodging, drought and nutrient imbalance. Silicon is taken up by the roots in the form ofsilicic acid, a noncharged molecule. Recently both influx (Lsil) and efflux (Lsi2) transporters for silicic acid have been identified in gramineous plants including rice, barley and maize. Lsil and its homologs are influx Si transporters, which belong to a Nod26-like major intrinsic protein (NIP) subfamily in the aquaporin protein family. They are responsible for the transport of Si from the external solution to the root cells. On the other hand, Lsi2 and its homologs are efflux Si transporters, belonging to putative anion transporters and are responsible for the transport of Si out of the cells toward the xylem. All influx transporters show polar localization at the distal side. Among efflux transporters, Lsi2 in rice shows polar localization at the proximal side, but that in barley and maize does not show polar localization. The cell-specificity of localization of Si transporters and expression patterns are different between species. Rice Si transporters are also permeable to arsenite.

  20. Radiation hormesis in higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Sung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-03-01

    The most remarkable aspect in the hormesis law is that low dose of harmful agents can produce effect that are diametrically opposite to the effect found with high doses of the same agent. Minute quantities of a harmful agent bring about very small change in the organism and control mechanisms appear to subjugate normal processes to place the organism in a state of alert and repair. The stimulated organism is more responsive to changes in environmental factors than it did before being alerted. Routine functions, including repair and defense, have priority for available energy and material. The alerted organism utilizes nutrients more efficiently, grows faster, shows improved defense reactions, matures faster, reproduces more effectively, has less disease, and lives longer. Accelerated germination, sprouting, growth, development, blooming and ripening, and increased crop yield and resistance to disease are found in plants. Another concept supported by the data is that low doses of ionizing radiation provide increased resistance to subsequent high doses of radiation. The hormesis varies with subject plant, variety, state of seed, environmental and cultural conditions, physiologic function measured, dose rate and total exposure. The results of hormesis are less consistently found, probably due to the great number of uncontrolled variables in the experiments. The general dosage for radiation hormesis in about 100 times ambient or 100 times less than a definitely harmful dose, but these must be modified to the occasion. Although little is known about most mechanisms of hormesis reaction, overcompensation of repair mechanism is offered as on mechanism. Radiation hormesis can provide more efficient use of resources, maximum production of foods, and increased health by the use of ionizing radiation as a useful tool in our technologic society. Efficient utilization of nature`s resources demands support to explore the practical application of radiation hormesis.

  1. Sucrose transporters of higher plants.

    Science.gov (United States)

    Kühn, Christina; Grof, Christopher P L

    2010-06-01

    Recent advances have provided new insights into how sucrose is moved from sites of synthesis to sites of utilisation or storage in sink organs. Sucrose transporters play a central role, as they orchestrate sucrose allocation both intracellularly and at the whole plant level. Sucrose produced in mesophyll cells of leaves may be effluxed into the apoplasm of mesophyll or phloem parenchyma cells by a mechanism that remains elusive, but experimentally consistent with facilitated transport or energy-dependent sucrose/H(+) antiport. From the apoplasm, sucrose/H(+) symporters transport sucrose across the plasma membrane of cells making up the sieve element/companion cell (SE/CC) complex, the long distance conduits of the phloem. Phloem unloading of sucrose in key sinks such as developing seeds involves two sequential transport steps, sucrose efflux followed by sucrose influx. Besides plasma membrane specific sucrose transporters, sucrose transporters on the tonoplast contribute to the capacity for elevated sucrose accumulation in storage organs such as sugar beet roots or sugarcane culms. Except for several sucrose facilitators from seed coats of some leguminous plants all sucrose transporters cloned to date, including recently identified vacuolar sucrose transporters, have been characterised as sucrose/H(+) symporters. Transporters functioning to efflux sucrose into source or sink apoplasms as well as those supporting sucrose/H(+) antiport on tonoplasts, remain to be identified. Sucrose transporter expression and activity is tightly regulated at the transcriptional, post-transcriptional as well as post-translational levels. Light quality and phytohormones play essential regulatory roles and the sucrose molecule itself functions as a signal. Copyright 2010 Elsevier Ltd. All rights reserved.

  2. Effector glycosyltransferases in Legionella

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    Yury eBelyi

    2011-04-01

    Full Text Available Legionella causes severe pneumonia in humans. The pathogen produces an array of effectors, which interfere with host cell functions. Among them are the glucosyltransferases Lgt1, Lgt2 and Lgt3 from L. pneumophila. Lgt1 and Lgt2 are produced predominately in the post-exponential phase of bacterial growth, while synthesis of Lgt3 is induced mainly in the lag-phase before intracellular replication of bacteria starts. Lgt glucosyltransferases are structurally similar to clostridial glucosylating toxins. The enzymes use UDP-glucose as a donor substrate and modify eukaryotic elongation factor eEF1A at serine-53. This modification results in inhibition of protein synthesis and death of target cells. In addition to Lgts, Legionella genomes disclose several genes, coding for effector proteins likely to possess glycosyltransferase activities, including SetA, which influences vesicular trafficking in the yeast model system and displays tropism for late endosomal/lysosomal compartments of mammalian cells. This review mainly discusses recent results on the structure-function relationship of Lgt glucosyltransferases.

  3. Acentrosomal microtubule nucleation in higher plants.

    Science.gov (United States)

    Schmit, Anne-Catherine

    2002-01-01

    Higher plants have developed a unique pathway to control their cytoskeleton assembly and dynamics. In most other eukaryotes, microtubules are nucleated in vivo at the nucleation and organizing centers and are involved in the establishment of polarity. Although the major cytoskeletal components are common to plant and animal cells, which suggests conserved regulation mechanisms, plants do not possess centrosome-like organelles. Nevertheless, they are able to build spindles and have developed their own specific cytoskeletal arrays: the cortical arrays, the preprophase band, and the phragmoplast, which all participate in basic developmental processes, as shown by defective mutants. New approaches provide essential clues to understanding the fundamental mechanisms of microtubule nucleation. Gamma-tubulin, which is considered to be the universal nucleator, is the essential component of microtubule-nucleating complexes identified as gamma-tubulin ring complexes (gamma-TuRC) in centriolar cells. A gamma-tubulin small complex (gamma-TuSC) forms a minimal nucleating unit recruited at specific sites of activity. These components--gamma-tubulin, Spc98p, and Spc97p--are present in higher plants. They play a crucial role in microtubule nucleation at the nuclear surface, which is known as the main functional plant microtubule-organizing center, and also probably at the cell cortex and at the phragmoplast, where secondary nucleation sites may exist. Surprisingly, plant gamma-tubulin is distributed along the microtubule length. As it is not associated with Spc98p, it may not be involved in microtubule nucleation, but may preferably control microtubule dynamics. Understanding the mechanisms of microtubule nucleation is the major challenge of the current research.

  4. Higher plant transformation: principles and molecular tools.

    Science.gov (United States)

    Anami, Sylvester; Njuguna, Elizabeth; Coussens, Griet; Aesaert, Stijn; Van Lijsebettens, Mieke

    2013-01-01

    In higher plants, genetic transformation, which is part of the toolbox for the study of living organisms, had been reported only 30 years ago, boosting basic plant biology research, generating superior crops, and leading to the new discipline of plant biotechnology. Here, we review its principles and the corresponding molecular tools. In vitro regeneration, through somatic embryogenesis or organogenesis, is discussed because they are prerequisites for the subsequent Agrobacterium tumefaciens-mediated transferred (T)-DNA or direct DNA transfer methods to produce transgenic plants. Important molecular components of the T-DNA are examined, such as selectable marker genes that allow the selection of transformed cells in tissue cultures and are used to follow the gene of interest in the next generations, and reporter genes that have been developed to visualize promoter activities, protein localizations, and protein-protein interactions. Genes of interest are assembled with promoters and termination signals in Escherichia coli by means of GATEWAY-derived binary vectors that represent the current versatile cloning tools. Finally, future promising developments in transgene technology are considered.

  5. Cytoplasniic differentiation during microsporogenesis in higher plants

    Directory of Open Access Journals (Sweden)

    H. Dichinnson

    2014-01-01

    Full Text Available Conspicuous cytoplasmic dedifferentiation in the pollen mother cells takes place early in the meiotic prophase of many plants. This event involves the removal of much of the cytoplasmic RNA. and the differentiation of both plastids and mitochondria to approaching the sole expression of their genomes. Much of the RNA removed from the cytoplasm passes to the nucleoplasm where it is utilised in the construction of a new `generation' of ribusomes. These new ribosomes are incorporated into cytoplasmic `nuclewhich disintegrate in the post-meiotic cytoplasm, restoring its ribosomes to pre-prophase levels. These changes are interpreted as evidence of a process by which the cytoplasm is cleansed of sporophytic control elements, both for the expression of the new gametophytic genome, and in the female cells of higher plants, for transmission to the new generation. The absence of control elements (presumably long-term messenger RNA from the cytoplasm would result in the dedifferentiation observed in the organelles, and the low levels of reserves in these cells presumably results in characteristically lengthy and unusual redifferentiation of both plastids and mitochondria, once information-carrying molecules again enter the cytosol.

  6. Mechanisms of male sterility in higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Yasuo (Tsukuba Univ., Sakura, Ibaraki (Japan))

    1982-03-01

    The mechanisms causing male sterility in higher plants were classified into two major categories: genetic and non-genetic. The former was further divided into six classes: 1) Anomality in spindle mechanism during meiosis, 2) chromosomal anomality such as haploidy, polyploidy, aneuploidy, chromosome some deficiency, inversion and reciprocal translocation, 3) presence of male sterile genes, 4) cytoplasmic abnormality, 5) the combination of some specific cytoplasm with particular genes, and 6) infections of microorganisms or viruses. Each mechanism was briefly explained, and the methods for the maintenance of parent lines for heterosis breeding and hybrid seed production were described. The non-genetic male sterility was classified into four types, which are caused by 1) low or high temperature, 2) water deficiency, 3) application of chemicals, and 4) radiation, with a brief explanation given for each of them.

  7. Effect of free fall on higher plants.

    Science.gov (United States)

    Gordon, S. A.

    1973-01-01

    The influence of exposure to the free-fall state on the orientation, morphogenesis, physiology, and radiation response of higher plants is briefly summarized. It is proposed that the duration of the space-flight experiments has been to brief to permit meaningful effects of free fall on general biochemistry, growth, and development to appear. However, two types of significant effect did occur. The first is on differential growth - i.e., tropism and epinasty - resulting from the absence of a normal geostimulus. For these phenomena it is suggested that ground-based experiments with the clinostat would suffice to mimic the effect of the free-fall state. The second is an apparent interaction between the radiation response and some flight condition, yielding an enhanced microspore abortion, a disturbed spindle function, and a stunting of stamen hairs. It is suggested that this apparent interaction may be derived from a shift in the rhythm of the cell cycle, induced by the free fall.

  8. The origin and function of platelet glycosyltransferases

    DEFF Research Database (Denmark)

    Wandall, Hans H; Rumjantseva, Viktoria; Sørensen, Anne Louise Tølbøll

    2012-01-01

    that megakaryocytes package these Golgi-derived glycosyltransferases into vesicles that are sent via proplatelets to nascent platelets, where they accumulate. These glycosyltransferases are active, and intact platelets glycosylate large exogenous substrates. Furthermore, we show that activation of platelets results...... to function in the extracellular space. This platelet glycosylation machinery offers a pathway to a simple glycoengineering strategy improving storage of platelets and may serve hitherto unknown biological functions....

  9. The origin and function of platelet glycosyltransferases.

    Science.gov (United States)

    Wandall, Hans H; Rumjantseva, Viktoria; Sørensen, Anne Louise Tølbøll; Patel-Hett, Sunita; Josefsson, Emma C; Bennett, Eric P; Italiano, Joseph E; Clausen, Henrik; Hartwig, John H; Hoffmeister, Karin M

    2012-07-19

    Platelets are megakaryocyte subfragments that participate in hemostatic and host defense reactions and deliver pro- and antiangiogenic factors throughout the vascular system. Although they are anucleated cells that lack a complex secretory apparatus with distinct Golgi/endoplasmic reticulum compartments, past studies have shown that platelets have glycosyltransferase activities. In the present study, we show that members of 3 distinct glycosyltransferase families are found within and on the surface of platelets. Immunocytology and flow cytometry results indicated that megakaryocytes package these Golgi-derived glycosyltransferases into vesicles that are sent via proplatelets to nascent platelets, where they accumulate. These glycosyltransferases are active, and intact platelets glycosylate large exogenous substrates. Furthermore, we show that activation of platelets results in the release of soluble glycosyltransferase activities and that platelets contain sufficient levels of sugar nucleotides for detection of glycosylation of exogenously added substrates. Therefore, the results of the present study show that blood platelets are a rich source of both glycosyltransferases and donor sugar substrates that can be released to function in the extracellular space. This platelet-glycosylation machinery offers a pathway to a simple glycoengineering strategy improving storage of platelets and may serve hitherto unknown biologic functions.

  10. The cytoskeleton and gravitropism in higher plants

    Science.gov (United States)

    Blancaflor, Elison B.

    2002-01-01

    The cellular and molecular mechanisms underlying the gravitropic response of plants have continued to elude plant biologists despite more than a century of research. Lately there has been increased attention on the role of the cytoskeleton in plant gravitropism, but several controversies and major gaps in our understanding of cytoskeletal involvement in gravitropism remain. A major question in the study of plant gravitropism is how the cytoskeleton mediates early sensing and signal transduction events in plants. Much has been made of the actin cytoskeleton as the cellular structure that sedimenting amyloplasts impinge upon to trigger the downstream signaling events leading to the bending response. There is also strong molecular and biochemical evidence that the transport of auxin, an important player in gravitropism, is regulated by actin. Organizational changes in microtubules during the growth response phase of gravitropism have also been well documented, but the significance of such reorientations in controlling differential cellular growth is unclear. Studies employing pharmacological approaches to dissect cytoskeletal involvement in gravitropism have led to conflicting results and therefore need to be interpreted with caution. Despite the current controversies, the revolutionary advances in molecular, biochemical, and cell biological techniques have opened up several possibilities for further research into this difficult area. The myriad proteins associated with the plant cytoskeleton that are being rapidly characterized provide a rich assortment of candidate regulators that could be targets of the gravity signal transduction chain. Cytoskeletal and ion imaging in real time combined with mutant analysis promises to provide a fresh start into this controversial area of research.

  11. The proteome of higher plant mitochondria.

    Science.gov (United States)

    Rao, R S P; Salvato, F; Thal, B; Eubel, H; Thelen, J J; Møller, I M

    2017-03-01

    Plant mitochondria perform a wide range of functions in the plant cell ranging from providing energy and metabolic intermediates, via coenzyme biosynthesis and their own biogenesis to retrograde signaling and programmed cell death. To perform these functions, they contain a proteome of >2000 different proteins expressed in some cells under some conditions. The vast majority of these proteins are imported, in many cases by a dedicated protein import machinery. Recent proteomic studies have identified about 1000 different proteins in both Arabidopsis and potato mitochondria, but even for energy-related proteins, the most well-studied functional protein group in mitochondria, <75% of the proteins are recognized as mitochondrial by even one of six of the most widely used prediction algorithms. The mitochondrial proteomes contain proteins representing a wide range of different functions. Some protein groups, like energy-related proteins, membrane transporters, and de novo fatty acid synthesis, appear to be well covered by the proteome, while others like RNA metabolism appear to be poorly covered possibly because of low abundance. The proteomic studies have improved our understanding of basic mitochondrial functions, have led to the discovery of new mitochondrial metabolic pathways and are helping us towards appreciating the dynamic role of the mitochondria in the responses of the plant cell to biotic and abiotic stress. Copyright © 2016 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

  12. Passive CO2 concentration in higher plants.

    Science.gov (United States)

    Sage, Rowan F; Khoshravesh, Roxana

    2016-06-01

    Photorespiratory limitations on C3 photosynthesis are substantial in warm, low CO2 conditions. To compensate, certain plants evolved mechanisms to actively concentrate CO2 around Rubisco using ATP-supported CO2 pumps such as C4 photosynthesis. Plants can also passively accumulate CO2 without additional ATP expenditure by localizing the release of photorespired and respired CO2 around Rubisco that is diffusively isolated from peripheral air spaces. Passive accumulation of photorespired CO2 occurs when glycine decarboxylase is localized to vascular sheath cells in what is termed C2 photosynthesis, and through forming sheaths of chloroplasts around the periphery of mesophyll cells. The peripheral sheaths require photorespired CO2 to re-enter chloroplasts where it can be refixed. Passive accumulation of respiratory CO2 is common in organs such as stems, fruits and flowers, due to abundant heterotrophic tissues and high diffusive resistance along the organ periphery. Chloroplasts within these organs are able to exploit this high CO2 to reduce photorespiration. CO2 concentration can also be enhanced passively by channeling respired CO2 from roots and rhizomes into photosynthetic cells of stems and leaves via lacunae, aerenchyma and the xylem stream. Through passive CO2 concentration, C3 species likely improved their carbon economy and maintained fitness during episodes of low atmospheric CO2. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Molecular farming: production of drugs and vaccines in higher plants.

    Science.gov (United States)

    Shinmyo, Atsuhiko; Kato, Ko

    2010-08-01

    On the basis of developments in plant biotechnology, drug and vaccine production by higher plants can be added to microbial and animal cell culture processes. When genes encoding drug or vaccine formation under a suitable promoter are introduced into plants, these useful compounds can be economically produced from CO(2) and inorganic chemicals using sunlight. The merits and demerits of the plant process are discussed in this paper.

  14. Potential cyclodextrin glycosyltransferase producer from locally ...

    African Journals Online (AJOL)

    hope&shola

    2010-10-25

    Oct 25, 2010 ... Cyclodextrin glycosyltransferase (CGTase) is one of the most important groups of microbial amylolytic enzymes that have been used for degradation of starch to yield cyclodextrin (CD) via cyclization reaction. The increasing demand for CD in industrial application has led to an extensive study about.

  15. Potential cyclodextrin glycosyltransferase producer from locally ...

    African Journals Online (AJOL)

    Cyclodextrin glycosyltransferase (CGTase) is one of the most important groups of microbial amylolytic enzymes that have been used for degradation of starch to yield cyclodextrin (CD) via cyclization reaction. The increasing demand for CD in industrial application has led to an extensive study about CGTase which begin ...

  16. Purification and characterisation of Cyclodextrin glycosyltransferase ...

    African Journals Online (AJOL)

    EXPER

    2012-06-05

    Jun 5, 2012 ... Cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) from a thermophilic anaerobic bacterium,. Thermoanaerobacter sp. P4, was purified by ammonium sulfate precipitation followed by α-cyclodextrin epoxy activated-sepharose 6B column chromatography. Enzyme was purified 141 fold and had the.

  17. Classification, Naming and Evolutionary History of Glycosyltransferases from Sequenced Green and Red Algal Genomes

    DEFF Research Database (Denmark)

    Ulvskov, Peter; Paiva, Dionisio Soares; Domozych, David

    2013-01-01

    of glycosyltransferases found in the Rhodophyta and Chlorophyta are generally much lower then in land plants (Embryophyta). Three specific features exhibited by land plants increase the number of glycosyltransferases in their genomes: (1) cell wall biosynthesis, the more complex land plant cell walls require a larger...... amongst the taxa of this study, clear distinctions or similarities were observed in (1) N-linked protein glycosylation, i.e., Chlorophyta has different mannosylation and glucosylation patterns, (2) GPI anchor biosynthesis, which is apparently missing in the Rhodophyta and truncated in the Chlorophyta, (3......) cell wall biosynthesis, where the land plants have unique cell wall related polymers not found in green and red algae, and (4) O-linked glycosylation where comprehensive orthology was observed in glycosylation between the Chlorophyta and land plants but not between the target proteins....

  18. Fractionation of metal stable isotopes by higher plants

    Science.gov (United States)

    Von Blanckenburg, F.; Von Wiren, N.; Guelke, M.; Weiss, D.J.; Bullen, T.D.

    2009-01-01

    Higher plants induce chemical reactions in the rhizosphere, facilitating metal uptake by roots. Fractionation of the isotopes in nutrients such as calcium, iron, magnesium, and zinc produces a stable isotope composition in the plants that generally differs from that of the growth medium. Isotope fractionation also occurs during transport of the metals within most plants, but its extent depends on plant species and on the metal, in particular, on the metal's redox state and what ligand it is bound to. The metal stable isotope variations observed in plants create an isotope signature of life at the Earth's surface, contributing substantially to our understanding of metal cycling processes in the environment and in individual organisms.

  19. Computational identification of candidate nucleotide cyclases in higher plants

    KAUST Repository

    Wong, Aloysius Tze

    2013-09-03

    In higher plants guanylyl cyclases (GCs) and adenylyl cyclases (ACs) cannot be identified using BLAST homology searches based on annotated cyclic nucleotide cyclases (CNCs) of prokaryotes, lower eukaryotes, or animals. The reason is that CNCs are often part of complex multifunctional proteins with different domain organizations and biological functions that are not conserved in higher plants. For this reason, we have developed CNC search strategies based on functionally conserved amino acids in the catalytic center of annotated and/or experimentally confirmed CNCs. Here we detail this method which has led to the identification of >25 novel candidate CNCs in Arabidopsis thaliana, several of which have been experimentally confirmed in vitro and in vivo. We foresee that the application of this method can be used to identify many more members of the growing family of CNCs in higher plants. © Springer Science+Business Media New York 2013.

  20. Classification, naming and evolutionary history of glycosyltransferases from sequenced green and red algal genomes.

    Directory of Open Access Journals (Sweden)

    Peter Ulvskov

    Full Text Available The Archaeplastida consists of three lineages, Rhodophyta, Virideplantae and Glaucophyta. The extracellular matrix of most members of the Rhodophyta and Viridiplantae consists of carbohydrate-based or a highly glycosylated protein-based cell wall while the Glaucophyte covering is poorly resolved. In order to elucidate possible evolutionary links between the three advanced lineages in Archaeplastida, a genomic analysis was initiated. Fully sequenced genomes from the Rhodophyta and Virideplantae and the well-defined CAZy database on glycosyltransferases were included in the analysis. The number of glycosyltransferases found in the Rhodophyta and Chlorophyta are generally much lower then in land plants (Embryophyta. Three specific features exhibited by land plants increase the number of glycosyltransferases in their genomes: (1 cell wall biosynthesis, the more complex land plant cell walls require a larger number of glycosyltransferases for biosynthesis, (2 a richer set of protein glycosylation, and (3 glycosylation of secondary metabolites, demonstrated by a large proportion of family GT1 being involved in secondary metabolite biosynthesis. In a comparative analysis of polysaccharide biosynthesis amongst the taxa of this study, clear distinctions or similarities were observed in (1 N-linked protein glycosylation, i.e., Chlorophyta has different mannosylation and glucosylation patterns, (2 GPI anchor biosynthesis, which is apparently missing in the Rhodophyta and truncated in the Chlorophyta, (3 cell wall biosynthesis, where the land plants have unique cell wall related polymers not found in green and red algae, and (4 O-linked glycosylation where comprehensive orthology was observed in glycosylation between the Chlorophyta and land plants but not between the target proteins.

  1. Predicting molybdenum toxicity to higher plants: Influence of soil properties

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, S.P., E-mail: steve.mcgrath@bbsrc.ac.u [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Mico, C. [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Curdy, R. [Laboratory for Environmental Biotechnology (LBE), Swiss Federal Institute of Technology Lausanne (EPFL) Station 6 CH, 1015 Lausanne (Switzerland); Zhao, F.J. [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom)

    2010-10-15

    The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED{sub 50}) of Mo in different soils, explaining > 65% of the variance in ED{sub 50} for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations. - Amorphous iron oxides or organic carbon were found to be the best predictors of the toxicity threshold values of Mo to higher plants on different soils.

  2. Higher plant vegetation changes during Pliocene sapropel formation

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Menzel, D.; Schouten, S.; Bergen, P.F. van

    2004-01-01

    The 13C values of higher plant wax C27 33 n-alkanes were determined in three, time-equivalent Pliocene (2.943 Ma) sapropels and homogeneous calcareous ooze from three different sites forming an east-west transect in the eastern Mediterranean Basin in order to study the composition of the vegetation

  3. Functional architecture of higher plant photosystem II supercomplexes

    NARCIS (Netherlands)

    Caffarri, Stefano; Kouril, Roman; Kereiche, Sami; Boekema, Egbert J.; Croce, Roberta; Kereïche, Sami

    2009-01-01

    Photosystem II ( PSII) is a large multiprotein complex, which catalyses water splitting and plastoquinone reduction necessary to transform sunlight into chemical energy. Detailed functional and structural studies of the complex from higher plants have been hampered by the impossibility to purify it

  4. Chlorine-containing natural compounds in higher plants

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen

    1986-01-01

    More than 130 chlorine-containing compounds have been isolated from higher plants and ferns; about half are polyacetylenes, thiophenes and sesquiterpene lactones from the Asteraceae. A chlorinated chlorophyll may be an important part of photosystem 1. High biological activity is found in 4-chloro......-chloroindoleacetic acid from pea and in the cancerostatic maytansinoids. Many compounds are chlorohydrins isolated along with the related epoxides. Some compounds, like gibberellin A6 hydrochloride from bean, are perhaps artefacts....

  5. Arabinogalactan Glycosyltransferases: Enzyme Assay, Protein-Protein Interaction, Subcellular Localization, and Perspectives for Application

    Directory of Open Access Journals (Sweden)

    Naomi Geshi

    2014-01-01

    Full Text Available Arabinogalactan proteins (AGPs are abundant extracellular proteoglycans that are found in most plant species and involved in many cellular processes, such as cell proliferation and survival, pattern formation, and growth, and in plant microbe interaction. AGPs are synthesized by posttranslational O-glycosylation of proteins and attached glycan part often constitutes greater than 90% of the molecule. Subtle altered glycan structures during development have been considered to function as developmental markers on the cell surface, but little is known concerning the molecular mechanisms. My group has been working on glycosylation enzymes (glycosyltransferases of AGPs to investigate glycan function of the molecule. This review summarizes the recent findings from my group as for AtGalT31A, AtGlcAT14A-C, and AtGalT29A of Arabidopsis thaliana with a specific focus on the (i biochemical enzyme activities; (ii subcellular compartments targeted by the glycosyltransferases; and (iii protein-protein interactions. I also discuss application aspect of glycosyltransferase in improving AGP-based product used in industry, for example, gum arabic.

  6. Screening of recombinant glycosyltransferases reveals the broad acceptor specificity of stevia UGT-76G1.

    Science.gov (United States)

    Dewitte, Griet; Walmagh, Maarten; Diricks, Margo; Lepak, Alexander; Gutmann, Alexander; Nidetzky, Bernd; Desmet, Tom

    2016-09-10

    UDP-glycosyltransferases (UGTs) are a promising class of biocatalysts that offer a sustainable alternative for chemical glycosylation of natural products. In this study, we aimed to characterize plant-derived UGTs from the GT-1 family with an emphasis on their acceptor promiscuity and their potential application in glycosylation processes. Recombinant expression in E. coli provided sufficient amounts of enzyme for the in-depth characterization of the salicylic acid UGT from Capsella rubella (UGT-SACr) and the stevia UGT from Stevia rebaudiana (UGT-76G1Sr). The latter was found to have a remarkably broad specificity with activities on a wide diversity of structures, from aliphatic and branched alcohols, over small phenolics to larger flavonoids, terpenoids and even higher glycoside compounds. As an example for its industrial potential, the glycosylation of curcumin was thoroughly evaluated. Under optimized conditions, 96% of curcumin was converted within 24h into the corresponding curcumin β-glycosides. In addition, the reaction was performed in a coupled system with sucrose synthase from Glycine max, to enable the cost-efficient (re)generation of UDP-Glc from sucrose as abundant and renewable resource. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Consideration of higher seismic loads at existing plants

    Energy Technology Data Exchange (ETDEWEB)

    Liebig, J.; Pellissetti, M.

    2015-07-01

    Because of advancement of methods in probabilistic seismic hazard analysis, plenty of existing plants face higher seismic loads as an obligation from the national authorities. In case of such obligations safety related structures and equipment have to be reevaluated or requalified for the increased seismic loads. The paper provides solutions for different kinds of structures and equipment inside the plant, avoiding cost intensive hardware exchange. Due to higher seismic loads different kinds of structures and equipment inside a plant have to be reevaluated. For civil structures, primary components, mechanical components, distribution lines and electrical and I&C equipment different innovative concepts will be applied to keep structures and equipment qualified for the higher seismic loads. Detailed analysis, including the modeling of non-linear phenomena, or minor structural upgrades are cost competitive, compared to cost intensive hardware exchanges. Several case studies regarding the re-evaluation and requalification of structures and equipment due to higher seismic loads are presented. It is shown how the creation of coupled finite element models and the consistent propagation of acceleration time histories through the soil, building and primary circuit lead to a significant load reduction Electrical and I&C equipment is reinforced by smart upgrades which increase the natural equipment frequencies. Therefore for all devices inside the cabinets the local acceleration will not increase and the seismic qualification will be maintained. The case studies cover both classical deterministic and probabilistic re-evaluations (fragility analysis). Furthermore, the substantial benefits of non-linear limit load evaluation, such as push-over analysis of buildings and limit load analysis of fuel assemblies, are demonstrated. (Author)

  8. Lead stress effects on physiobiochemical activities of higher plants.

    Science.gov (United States)

    Sengar, Rakesh Singh; Gautam, Madhu; Sengar, Rajesh Singh; Garg, Sanjay Kumar; Sengar, Kalpana; Chaudhary, Reshu

    2008-01-01

    Lead is a metallic pollutant emanating from various environmental sources including industrial wastes, combustion of fossil fuels, and use of agrochemicals. Lead may exist in the atmosphere as dusts, fumes, mists, and vapors, and in soil as a mineral. Soils along roadsides are rich in lead because vehicles burn leaded gasoline, which contributes to environmental lead pollution. Other important sources of lead pollution are geological weathering, industrial processing of ores and minerals, leaching of lead from solid wastes, and animal and human excreta. Lead is nondegradable, readily enters the food chain, and can subsequently endanger human and animal health. Lead is one of the most important environment pollutants and deserves the increasing attention it has received in recent decades. The present effort was undertaken to review lead stress effects on the physiobiochemical activity of higher plants. Lead has gained considerable attention as a potent heavy metal pollutant because of growing anthropogenic pressure on the environment. Lead-contaminated soils show a sharp decline in crop productivity. Lead is absorbed by plants mainly through the root system and in minor amounts through the leaves. Within the plants, lead accumulates primarily in roots, but some is translocated to aerial plant parts. Soil pH, soil particle size, cation-exchange capacity, as well as root surface area, root exudation, and mycorrhizal transpiration rate affect the availability and uptake of lead by plants. Only a limited amount of lead is translocated from roots to other organs because there are natural plant barriers in the root endodermis. At lethal concentrations, this barrier is broken and lead may enter vascular tissues. Lead in plants may form deposits of various sizes, present mainly in intercellular spaces, cell walls, and vacuoles. Small deposits of this metal are also seen in the endoplasmic reticulum, dictyosome, and dictyosome-derived vesicles. After entering the cells, lead

  9. Cloning higher plants from aseptically cultured tissues and cells

    Science.gov (United States)

    Krikorian, A. D.

    1982-01-01

    A review of aseptic culture methods for higher plants is presented, which focuses on the existing problems that limit or prevent the full realization of cloning plants from free cells. It is shown that substantial progress in clonal multiplication has been made with explanted stem tips or lateral buds which can be stimulated to produce numerous precocious axillary branches. These branches can then be separated or subdivided and induced to root in order to yield populations of genetically and phenotypically uniorm plantlets. Similarly, undifferentiated calluses can sometimes be induced to form shoots and/or roots adventitiously. Although the cell culture techniques required to produce somatic embryos are presently rudimentary, steady advances are being made in learning how to stimulate formation of somatic or adventive embryos from totipotent cells grown in suspension cultures. It is concluded that many problems exist in the producing and growing of totipotent or morphogenetically competent cell suspensions, but the potential benefits are great.

  10. A Bifunctional Glycosyltransferase from Agrobacterium tumefaciens Synthesizes Monoglucosyl and Glucuronosyl Diacylglycerol under Phosphate Deprivation*

    Science.gov (United States)

    Semeniuk, Adrian; Sohlenkamp, Christian; Duda, Katarzyna; Hölzl, Georg

    2014-01-01

    Glycolipids are mainly found in phototrophic organisms (like plants and cyanobacteria), in Gram-positive bacteria, and a few other bacterial phyla. Besides the function as bulk membrane lipids, they often play a role under phosphate deprivation as surrogates for phospholipids. The Gram-negative Agrobacterium tumefaciens accumulates four different glycolipids under phosphate deficiency, including digalactosyl diacylglycerol and glucosylgalactosyl diacylglycerol synthesized by a processive glycosyltransferase. The other two glycolipids have now been identified by mass spectrometry and nuclear magnetic resonance spectroscopy as monoglucosyl diacylglycerol and glucuronosyl diacylglycerol. These two lipids are synthesized by a single promiscuous glycosyltransferase encoded by the ORF atu2297, with UDP-glucose or UDP-glucuronic acid as sugar donors. The transfer of sugars differing in their chemistry is a novel feature not observed before for lipid glycosyltransferases. Furthermore, this enzyme is the first glucuronosyl diacylglycerol synthase isolated. Deletion mutants of Agrobacterium lacking monoglucosyl diacylglycerol and glucuronosyl diacylglycerol or all glycolipids are not impaired in growth or virulence during infection of tobacco leaf discs. Our data suggest that the four glycolipids and the nonphospholipid diacylglyceryl trimethylhomoserine can mutually replace each other during phosphate deprivation. This redundancy of different nonphospholipids may represent an adaptation mechanism to enhance the competitiveness in nature. PMID:24558041

  11. Functional characterization of a flavonoid glycosyltransferase gene from Withania somnifera (Ashwagandha).

    Science.gov (United States)

    Singh, Somesh; Vishwakarma, Rishi K; Kumar, R J Santosh; Sonawane, Prashant D; Ruby; Khan, Bashir M

    2013-06-01

    Glycosylation of flavonoids is mediated by family 1 uridine diphosphate (UDP)-dependent glycosyltransferases (UGTs). Until date, there are few reports on functionally characterized flavonoid glycosyltransferases from Withania somnifera. In this study, we cloned the glycosyltransferase gene from W. somnifera (UGT73A16) showing 85-92 % homology with UGTs from other plants. UGT73A16 was expressed as a His(6)-tagged fusion protein in Escherichia coli. Several compounds, including flavonoids, were screened as potential substrates for UGT73A16. HPLC analysis and hypsochromic shift indicated that UGT73A16 transfers a glucose molecule to several different flavonoids. Based on kinetic parameters, UGT73A16 shows more catalytic efficiency towards naringenin. Here, we explored UGT73A16 of W. somnifera as whole cell catalyst in E. coli. We used flavonoids (genistein, apigenin, kaempferol, naringenin, biochanin A, and daidzein) as substrates for this study. More than 95 % of the glucoside products were released into the medium, facilitating their isolation. Glycosylation of substrates occurred on the 7- and 3-hydroxyl group of the aglycone. UGT73A16 also displayed regiospecific glucosyl transfer activity towards 3-hydroxy flavone compound, which is the backbone of all flavonols and also for a chemically synthesized compound, not found naturally. The present study generates essential knowledge and molecular as well as biochemical tools that allow the verification of UGT73A16 in glycosylation.

  12. Metabolic engineering of higher plants and algae for isoprenoid production.

    Science.gov (United States)

    Kempinski, Chase; Jiang, Zuodong; Bell, Stephen; Chappell, Joe

    2015-01-01

    Isoprenoids are a class of compounds derived from the five carbon precursors, dimethylallyl diphosphate, and isopentenyl diphosphate. These molecules present incredible natural chemical diversity, which can be valuable for humans in many aspects such as cosmetics, agriculture, and medicine. However, many terpenoids are only produced in small quantities by their natural hosts and can be difficult to generate synthetically. Therefore, much interest and effort has been directed toward capturing the genetic blueprint for their biochemistry and engineering it into alternative hosts such as plants and algae. These autotrophic organisms are attractive when compared to traditional microbial platforms because of their ability to utilize atmospheric CO2 as a carbon substrate instead of supplied carbon sources like glucose. This chapter will summarize important techniques and strategies for engineering the accumulation of isoprenoid metabolites into higher plants and algae by choosing the correct host, avoiding endogenous regulatory mechanisms, and optimizing potential flux into the target compound. Future endeavors will build on these efforts by fine-tuning product accumulation levels via the vast amount of available "-omic" data and devising metabolic engineering schemes that integrate this into a whole-organism approach. With the development of high-throughput transformation protocols and synthetic biology molecular tools, we have only begun to harness the power and utility of plant and algae metabolic engineering.

  13. Protein engineering of cyclodextrin glycosyltransferase from Bacillus circulans strain 251

    NARCIS (Netherlands)

    Penninga, Dirk

    1996-01-01

    An enormous diversity of molecular functions in living organisms is carried out by proteins. Our studies have focussed on the functional analysis of a starch-converting enzyme, cyclodextrin glycosyltransferase (CGTase) from Bacillus circulans strain 251. Zie: Summary

  14. GLYCOSYLTRANSFERASE GLYCOSYLATING FLAVOKERMESIC ACID AND/OR KERMESIC ACID

    DEFF Research Database (Denmark)

    2015-01-01

    An isolated glycosyltransferase (GT) polypeptide capable of: (I): conjugating glucose to flavokermesic acid (FK); and/or (II): conjugating glucose to kermesic acid (KA) and use of this GT to e.g. make Carminic acid.......An isolated glycosyltransferase (GT) polypeptide capable of: (I): conjugating glucose to flavokermesic acid (FK); and/or (II): conjugating glucose to kermesic acid (KA) and use of this GT to e.g. make Carminic acid....

  15. Plant invasion is associated with higher plant-soil nutrient concentrations in nutrient-poor environments.

    Science.gov (United States)

    Sardans, Jordi; Bartrons, Mireia; Margalef, Olga; Gargallo-Garriga, Albert; Janssens, Ivan A; Ciais, Phillipe; Obersteiner, Michael; Sigurdsson, Bjarni D; Chen, Han Y H; Peñuelas, Josep

    2017-03-01

    Plant invasion is an emerging driver of global change worldwide. We aimed to disentangle its impacts on plant-soil nutrient concentrations. We conducted a meta-analysis of 215 peer-reviewed articles and 1233 observations. Invasive plant species had globally higher N and P concentrations in photosynthetic tissues but not in foliar litter, in comparison with their native competitors. Invasive plants were also associated with higher soil C and N stocks and N, P, and K availabilities. The differences in N and P concentrations in photosynthetic tissues and in soil total C and N, soil N, P, and K availabilities between invasive and native species decreased when the environment was richer in nutrient resources. The results thus suggested higher nutrient resorption efficiencies in invasive than in native species in nutrient-poor environments. There were differences in soil total N concentrations but not in total P concentrations, indicating that the differences associated to invasive plants were related with biological processes, not with geochemical processes. The results suggest that invasiveness is not only a driver of changes in ecosystem species composition but that it is also associated with significant changes in plant-soil elemental composition and stoichiometry. © 2016 John Wiley & Sons Ltd.

  16. Catalytic and thermodynamic properties of glycosylated Bacillus cereus cyclodextrin glycosyltransferase.

    Science.gov (United States)

    Abdel-Naby, Mohamed A; Fouad, Ahmed A; El-Refai, H A

    2015-05-01

    Cyclodextrin glycosyltransferase (CGTase) was covalently coupled to five oxidized polysaccharides differing in structure and chemical nature. The conjugates were evaluated for the retained activity, kinetic and thermodynamic stability. The conjugated CGTase with oxidized dextran (MW 47000) had the highest retained specific activity (70.05%) and the highest half-life (T1/2) at 80°C. Compared to the native enzyme, the conjugated preparation exhibited higher optimum temperature, lower activation energy (Ea), lower deactivation constant rate (kd), higher T1/2, and higher D values (decimal reduction time) within the temperature range of 60-80°C. The values of thermodynamic parameters for irreversible inactivation of native and conjugated CGTase indicated that conjugation significantly decreased entropy (ΔS*) and enthalpy of deactivation (ΔH*). The results of thermodynamic analysis for cyclodextrin production from starch indicated that The enthalpy of activation (ΔH*) and free energy of activation (ΔG*), (free energy of transition state) ΔG*E-T and (free energy of substrate binding) ΔG*E-S values were lower for the conjugated CGTase. Similarly, there was significant impact on improvement of kcat, kcat/Km values. Both native and conjugated enzyme produce α-cyclodextrin from starch. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Functional architecture of higher plant photosystem II supercomplexes.

    Science.gov (United States)

    Caffarri, Stefano; Kouril, Roman; Kereïche, Sami; Boekema, Egbert J; Croce, Roberta

    2009-10-07

    Photosystem II (PSII) is a large multiprotein complex, which catalyses water splitting and plastoquinone reduction necessary to transform sunlight into chemical energy. Detailed functional and structural studies of the complex from higher plants have been hampered by the impossibility to purify it to homogeneity. In this work, homogeneous preparations ranging from a newly identified particle composed by a monomeric core and antenna proteins to the largest C(2)S(2)M(2) supercomplex were isolated. Characterization by biochemical methods and single particle electron microscopy allowed to relate for the first time the supramolecular organization to the protein content. A projection map of C(2)S(2)M(2) at 12 A resolution was obtained, which allowed determining the location and the orientation of the antenna proteins. Comparison of the supercomplexes obtained from WT and Lhcb-deficient plants reveals the importance of the individual subunits for the supramolecular organization. The functional implications of these findings are discussed and allow redefining previous suggestions on PSII energy transfer, assembly, photoinhibition, state transition and non-photochemical quenching.

  18. UGT74D1 is a novel auxin glycosyltransferase from Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Shang-Hui Jin

    Full Text Available Auxin is one type of phytohormones that plays important roles in nearly all aspects of plant growth and developmental processes. The glycosylation of auxins is considered to be an essential mechanism to control the level of active auxins. Thus, the identification of auxin glycosyltransferases is of great significance for further understanding the auxin regulation. In this study, we biochemically screened the group L of Arabidopsis thaliana glycosyltransferase superfamily for enzymatic activity toward auxins. UGT74D1 was identified to be a novel auxin glycosyltransferase. Through HPLC and LC-MS analysis of reaction products in vitro by testing eight substrates including auxins and other compounds, we found that UGT74D1 had a strong glucosylating activity toward indole-3-butyric acid [IBA], indole-3-propionic acid [IPA], indole-3-acetic acid [IAA] and naphthaleneacetic acid [NAA], catalyzing them to form corresponding glucose esters. Biochemical characterization showed that this enzyme had a maximum activity in HEPES buffer at pH 6.0 and 37°C. In addition, the enzymatic activity analysis of crude protein and the IBA metabolite analysis from transgenic Arabidopsis plants overexpressing UGT74D1 gene were also carried out. Experimental results indicated that over-production of the UGT74D1 in plants indeed led to increased level of the glucose conjugate of IBA. Moreover, UGT74D1 overexpression lines displayed curling leaf phenotype, suggesting a physiological role of UGT74D1 in affecting the activity of auxins. Our current data provide a new target gene for further genetic studies to understand the auxin regulation by glycosylation in plants.

  19. Functional Characterization of a New Tea (Camellia sinensis) Flavonoid Glycosyltransferase.

    Science.gov (United States)

    Zhao, Xianqian; Wang, Peiqiang; Li, Mingzhuo; Wang, Yeru; Jiang, Xiaolan; Cui, Lilan; Qian, Yumei; Zhuang, Juhua; Gao, Liping; Xia, Tao

    2017-03-15

    Tea (Camellia sinensis) is an important commercial crop, in which the high content of flavonoids provides health benefits. A flavonoid glycosyltransferase (CsUGT73A20), belonging to cluster IIIa, was isolated from tea plant. The recombinant CsUGT73A20 in Escherichia coli exhibited a broad substrate tolerance toward multiple flavonoids. Among them, kaempferol was the optimal substrate compared to quercetin, myricetin, naringenin, apigenin, and kaempferide. However, no product was detected when UDP-galactose was used as the sugar donor. The reaction assay indicated that rCsUGT73A20 performed multisite glycosidation toward flavonol compounds, mainly forming 3-O-glucoside and 7-O-glucoside in vitro. The biochemical characterization analysis of CsUGT73A20 showed more K7G product accumulated at pH 8.0, but K3G was the main product at pH 9.0. Kinetic analysis demonstrated that high pH repressed the glycosylation reaction at the 7-OH site in vitro. Besides, the content of five flavonol-glucosides was increased in CsUGT73A20-overexpressing tobaccos (Nicotiana tabacum).

  20. Water-Wisteria as an ideal plant to study heterophylly in higher aquatic plants.

    Science.gov (United States)

    Li, Gaojie; Hu, Shiqi; Yang, Jingjing; Schultz, Elizabeth A; Clarke, Kurtis; Hou, Hongwei

    2017-08-01

    The semi-aquatic plant Water-Wisteria is suggested as a new model to study heterophylly due to its many advantages and typical leaf phenotypic plasticity in response to environmental factors and phytohormones. Water-Wisteria, Hygrophila difformis (Acanthaceae), is a fast growing semi-aquatic plant that exhibits a variety of leaf shapes, from simple leaves to highly branched compound leaves, depending on the environment. The phenomenon by which leaves change their morphology in response to environmental conditions is called heterophylly. In order to investigate the characteristics of heterophylly, we assessed the morphology and anatomy of Hygrophila difformis in different conditions. Subsequently, we verified that phytohormones and environmental factors can induce heterophylly and found that Hygrophila difformis is easily propagated vegetatively through either leaf cuttings or callus induction, and the callus can be easily transformed by Agrobacterium tumefaciens. These results suggested that Hygrophila difformis is a good model plant to study heterophylly in higher aquatic plants.

  1. Higher Plants in life support systems: design of a model and plant experimental compartment

    Science.gov (United States)

    Hezard, Pauline; Farges, Berangere; Sasidharan L, Swathy; Dussap, Claude-Gilles

    The development of closed ecological life support systems (CELSS) requires full control and efficient engineering for fulfilling the common objectives of water and oxygen regeneration, CO2 elimination and food production. Most of the proposed CELSS contain higher plants, for which a growth chamber and a control system are needed. Inside the compartment the development of higher plants must be understood and modeled in order to be able to design and control the compartment as a function of operating variables. The plant behavior must be analyzed at different sub-process scales : (i) architecture and morphology describe the plant shape and lead to calculate the morphological parameters (leaf area, stem length, number of meristems. . . ) characteristic of life cycle stages; (ii) physiology and metabolism of the different organs permit to assess the plant composition depending on the plant input and output rates (oxygen, carbon dioxide, water and nutrients); (iii) finally, the physical processes are light interception, gas exchange, sap conduction and root uptake: they control the available energy from photosynthesis and the input and output rates. These three different sub-processes are modeled as a system of equations using environmental and plant parameters such as light intensity, temperature, pressure, humidity, CO2 and oxygen partial pressures, nutrient solution composition, total leaf surface and leaf area index, chlorophyll content, stomatal conductance, water potential, organ biomass distribution and composition, etc. The most challenging issue is to develop a comprehensive and operative mathematical model that assembles these different sub-processes in a unique framework. In order to assess the parameters for testing a model, a polyvalent growth chamber is necessary. It should permit a controlled environment in order to test and understand the physiological response and determine the control strategy. The final aim of this model is to have an envi

  2. Reconciling functions and evolution of isoprene emission in higher plants.

    Science.gov (United States)

    Loreto, Francesco; Fineschi, Silvia

    2015-04-01

    Compilation and analysis of existing inventories reveal that isoprene is emitted by c. 20% of the perennial vegetation of tropical and temperate regions of the world. Isoprene emitters are found across different plant families without any clear phylogenetic thread. However, by critically appraising information in inventories, several ecological patterns of isoprene emission can be highlighted, including absence of emission from C4 and annual plants, and widespread emission from perennial and deciduous plants of temperate environments. Based on this analysis, and on available information on biochemistry, ecology and functional roles of isoprene, it is suggested that isoprene may not have evolved to help plants face heavy or prolonged stresses, but rather assists C3 plants to run efficient photosynthesis and to overcome transient and mild stresses, especially during periods of active plant growth in warm seasons. When the stress status persists, or when evergreen leaves cope with multiple and repeated stresses, isoprene biosynthesis is replaced by the synthesis of less volatile secondary compounds, in part produced by the same biochemical pathway, thus indicating causal determinism in the evolution of isoprene-emitting plants in response to the environment. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  3. Generation of monoclonal antibodies to native active human glycosyltransferases

    DEFF Research Database (Denmark)

    Vester-Christensen, Malene Bech; Bennett, Eric Paul; Clausen, Henrik

    2013-01-01

    using monoclonal antibodies therefore provides an excellent strategy to analyze the glycosylation process in cells. A major drawback has been difficulties in generating antibodies to glycosyltransferases and validating their specificities. Here we describe a simple strategy for generating...... and characterizing monoclonal antibodies to human glycosyltransferases. This strategy includes a process for recombinant production and purification of enzymes for immunization, a simple selection strategy for isolation of antibodies with optimal properties for in situ detection of enzyme expression......, and a comprehensive strategy for characterizing the fine specificity of such antibodies....

  4. Glycosyltransferases from oat (Avena) implicated in the acylation of avenacins.

    Science.gov (United States)

    Owatworakit, Amorn; Townsend, Belinda; Louveau, Thomas; Jenner, Helen; Rejzek, Martin; Hughes, Richard K; Saalbach, Gerhard; Qi, Xiaoquan; Bakht, Saleha; Roy, Abhijeet Deb; Mugford, Sam T; Goss, Rebecca J M; Field, Robert A; Osbourn, Anne

    2013-02-08

    Plants produce a huge array of specialized metabolites that have important functions in defense against biotic and abiotic stresses. Many of these compounds are glycosylated by family 1 glycosyltransferases (GTs). Oats (Avena spp.) make root-derived antimicrobial triterpenes (avenacins) that provide protection against soil-borne diseases. The ability to synthesize avenacins has evolved since the divergence of oats from other cereals and grasses. The major avenacin, A-1, is acylated with N-methylanthranilic acid. Previously, we have cloned and characterized three genes for avenacin synthesis (for the triterpene synthase SAD1, a triterpene-modifying cytochrome P450 SAD2, and the serine carboxypeptidase-like acyl transferase SAD7), which form part of a biosynthetic gene cluster. Here, we identify a fourth member of this gene cluster encoding a GT belonging to clade L of family 1 (UGT74H5), and show that this enzyme is an N-methylanthranilic acid O-glucosyltransferase implicated in the synthesis of avenacin A-1. Two other closely related family 1 GTs (UGT74H6 and UGT74H7) are also expressed in oat roots. One of these (UGT74H6) is able to glucosylate both N-methylanthranilic acid and benzoic acid, whereas the function of the other (UGT74H7) remains unknown. Our investigations indicate that UGT74H5 is likely to be key for the generation of the activated acyl donor used by SAD7 in the synthesis of the major avenacin, A-1, whereas UGT74H6 may contribute to the synthesis of other forms of avenacin that are acylated with benzoic acid.

  5. Glycosyltransferases from Oat (Avena) Implicated in the Acylation of Avenacins*

    Science.gov (United States)

    Owatworakit, Amorn; Townsend, Belinda; Louveau, Thomas; Jenner, Helen; Rejzek, Martin; Hughes, Richard K.; Saalbach, Gerhard; Qi, Xiaoquan; Bakht, Saleha; Roy, Abhijeet Deb; Mugford, Sam T.; Goss, Rebecca J. M.; Field, Robert A.; Osbourn, Anne

    2013-01-01

    Plants produce a huge array of specialized metabolites that have important functions in defense against biotic and abiotic stresses. Many of these compounds are glycosylated by family 1 glycosyltransferases (GTs). Oats (Avena spp.) make root-derived antimicrobial triterpenes (avenacins) that provide protection against soil-borne diseases. The ability to synthesize avenacins has evolved since the divergence of oats from other cereals and grasses. The major avenacin, A-1, is acylated with N-methylanthranilic acid. Previously, we have cloned and characterized three genes for avenacin synthesis (for the triterpene synthase SAD1, a triterpene-modifying cytochrome P450 SAD2, and the serine carboxypeptidase-like acyl transferase SAD7), which form part of a biosynthetic gene cluster. Here, we identify a fourth member of this gene cluster encoding a GT belonging to clade L of family 1 (UGT74H5), and show that this enzyme is an N-methylanthranilic acid O-glucosyltransferase implicated in the synthesis of avenacin A-1. Two other closely related family 1 GTs (UGT74H6 and UGT74H7) are also expressed in oat roots. One of these (UGT74H6) is able to glucosylate both N-methylanthranilic acid and benzoic acid, whereas the function of the other (UGT74H7) remains unknown. Our investigations indicate that UGT74H5 is likely to be key for the generation of the activated acyl donor used by SAD7 in the synthesis of the major avenacin, A-1, whereas UGT74H6 may contribute to the synthesis of other forms of avenacin that are acylated with benzoic acid. PMID:23258535

  6. Biochemical Hydrogen Isotope Fractionation during Lipid Biosynthesis in Higher Plants

    Science.gov (United States)

    Kahmen, A.; Gamarra, B.; Cormier, M. A.

    2014-12-01

    Although hydrogen isotopes (δ2H) of leaf wax lipids are increasingly being applied as (paleo-) hydrological proxies, we still do not understand some of the basic processes that shape the δ2H values of these compounds. In general, it is believed that three variables shape the δ2H values of leaf wax lipids: source water δ2H values, evaporative deuterium (2H) enrichment of leaf water and the biosynthetic fractionation (ɛbio) during the synthesis of organic compounds. While the influences of source water δ2H values and leaf water evaporative 2H enrichment have been well documented, very little is known how ɛbio shapes the δ2H values of plant-derived lipids. I will present the results from recent experiments, where we show that the magnitude of ɛbio, and thus the δ2H value of plant-derived lipids, strongly depends on the carbon (C) metabolism of a plant. Specifically, I will show that plants that rely for their tissue formation on recently assimilated C have δ2H values in their n-alkanes that are up to 60‰ more negative than plants that depend for their tissue formation on stored carbohydrates. Our findings can be explained by the fact that NADPH is the primary source of hydrogen in plant lipids and that the δ2H value of NADPH differs whether NADPH was generated directly in the light reaction of photosynthesis or whether it was generated by processing stored carbohydrates. As such, the δ2H values of plant-derived lipids will directly depend on whether the tissue containing these lipids was synthesized using recent assimilates, e.g. in a C autonomous state or, if it was synthesized from stored or otherwise aquired C sources, e.g. in a not C autonomous state. Given the magnidude of this effect, our results have important implications for interpretation of plant-derived lipid δ2H values when used as (paleo-) hydrological proxies. In addition, our results suggest, that δ2H values of plant-derived lipids could be employed as a new tools to assess the C

  7. Penetration and Toxicity of Nanomaterials in Higher Plants

    Directory of Open Access Journals (Sweden)

    Giuseppe Chichiriccò

    2015-05-01

    Full Text Available Nanomaterials (NMs comprise either inorganic particles consisting of metals, oxides, and salts that exist in nature and may be also produced in the laboratory, or organic particles originating only from the laboratory, having at least one dimension between 1 and 100 nm in size. According to shape, size, surface area, and charge, NMs have different mechanical, chemical, electrical, and optical properties that make them suitable for technological and biomedical applications and thus they are being increasingly produced and modified. Despite their beneficial potential, their use may be hazardous to health owing to the capacity to enter the animal and plant body and interact with cells. Studies on NMs involve technologists, biologists, physicists, chemists, and ecologists, so there are numerous reports that are significantly raising the level of knowledge, especially in the field of nanotechnology; however, many aspects concerning nanobiology remain undiscovered, including the interactions with plant biomolecules. In this review we examine current knowledge on the ways in which NMs penetrate plant organs and interact with cells, with the aim of shedding light on the reactivity of NMs and toxicity to plants. These points are discussed critically to adjust the balance with regard to the risk to the health of the plants as well as providing some suggestions for new studies on this topic.

  8. Control of sexuality by the sk1-encoded UDP-glycosyltransferase of maize.

    Science.gov (United States)

    Hayward, Andrew P; Moreno, Maria A; Howard, Thomas P; Hague, Joel; Nelson, Kimberly; Heffelfinger, Christopher; Romero, Sandra; Kausch, Albert P; Glauser, Gaétan; Acosta, Ivan F; Mottinger, John P; Dellaporta, Stephen L

    2016-10-01

    Sex determination in maize involves the production of staminate and pistillate florets from an initially bisexual floral meristem. Pistil elimination in staminate florets requires jasmonic acid signaling, and functional pistils are protected by the action of the silkless 1 (sk1) gene. The sk1 gene was identified and found to encode a previously uncharacterized family 1 uridine diphosphate glycosyltransferase that localized to the plant peroxisomes. Constitutive expression of an sk1 transgene protected all pistils in the plant, causing complete feminization, a gain-of-function phenotype that operates by blocking the accumulation of jasmonates. The segregation of an sk1 transgene was used to effectively control the production of pistillate and staminate inflorescences in maize plants.

  9. An alkaliphilic cyclodextrin glycosyltransferase from a new Bacillus ...

    African Journals Online (AJOL)

    Alkaliphilic bacteria were isolated from soil and water samples obtained from Egyptian soda lakes in the Wadi Natrun area. Screening for cyclodextrin glycosyltransferase- producing alkaliphilic bacteria resulted in the isolation of 15 positive strains. Strain WN-I was selected as the best producer of CGTase. 16S rDNA ...

  10. Geometric attributes of retaining glycosyltransferase enzymes favor an orthogonal mechanism.

    Directory of Open Access Journals (Sweden)

    Brock Schuman

    Full Text Available Retaining glycosyltransferase enzymes retain the stereochemistry of the donor glycosidic linkage after transfer to an acceptor molecule. The mechanism these enzymes utilize to achieve retention of the anomeric stereochemistry has been a matter of much debate. Re-analysis of previously released structural data from retaining and inverting glycosyltransferases allows competing mechanistic proposals to be evaluated. The binding of metal-nucleotide-sugars between inverting and retaining enzymes is conformationally unique and requires the donor substrate to occupy two different orientations in the two types of glycosyltransferases. The available structures of retaining glycosyltransferases lack appropriately positioned enzymatic dipolar residues to initiate or stabilize the intermediates of a dissociative mechanism. Further, available structures show that the acceptor nucleophile and anomeric carbon of the donor sugar are in close proximity. Structural features support orthogonal (front-side attack from a position lying ≤ 90° from the C1-O phosphate bond for retaining enzymes. These structural conclusions are consistent with the geometric conclusions of recent kinetic and computational studies.

  11. Ecological Risk Assessment of Genetically Modified Higher Plants (GMHP)

    DEFF Research Database (Denmark)

    Kjær, C.; Damgaard, C.; Kjellsson, G.

    altered management of the fields, e.g. possible changes in for example leaching of pesticides or nitrogen, etc. Furthermore, we have abstained from suggesting number of species to test for specific issues because different risk assessment procedures have been developed which add a safety factor accounting...... for uncertainties in the extrapolation from limited laboratory studies to the species rich field environment. The relationship between the size of the safety factor and the number of species is therefore an issue of the risk assessment. Some of the issues raised in this report overlap with data needs...... of the project Biotechnology: elements in environmental risk assessment of genetically modified plants. December 1999 Christian Kjær Introduction In ecological risk assessment of transgenic plants, information on a wide range of subjects is needed for an effective and reliable assessment procedure...

  12. Molecular biology of gibberellins signaling in higher plants.

    Science.gov (United States)

    Itoh, Hironori; Ueguchi-Tanaka, Miyako; Matsuoka, Makoto

    2008-01-01

    Gibberellins (GAs), a large family of tetracyclic, diterpenoid plant hormones, play an important role in regulating diverse processes throughout plant development. In recent years, significant advances have been made in the isolation of GA signaling components and GA-responsive genes. All available data have indicated that DELLA proteins are an essential negative regulator in the GA signaling pathway and GA derepresses DELLA-mediated growth suppression by inducing degradation of DELLA proteins through the ubiquitin-26S proteasome proteolytic pathway. Identification of GID1, a gene encoding an unknown protein with similarity to hormone-sensitive lipases, has revealed that GID1 acts as a functional GA receptor with a reasonable binding affinity to biologically active GAs. Furthermore, the GID1 receptor interacts with DELLA proteins in a GA-dependent manner. These results suggest that formation of a GID1-GA-DELLA protein complex targets DELLA protein into the ubiquitin-26S proteasome pathway for degradation.

  13. Emission of NO from several higher plant species

    Science.gov (United States)

    Wildt, J.; Kley, D.; Rockel, A.; Rockel, P.; Segschneider, H. J.

    1997-03-01

    Emission of nitric oxide (NO) from a variety of plant species was observed in a continuously stirred tank reactor. During daytime and at NO concentrations below 1 ppb in the chamber air, NO emissions were observed for all studied nitrate-nourished plant species. A relation was found between the NO emission rates during daytime and the uptake rates of CO2. The ratio of the NO emission rate to the CO2 uptake was similar for all plants. Changes of the net rate of photosynthesis induced by variations of light intensity or changes of CO2 concentrations changed the NO emission rates correspondingly. The link between NO emissions and CO2 uptake during daytime allowed estimation of the potential of the vegetation to evolve NO on a global scale as 0.23 Tg N yr-1. Strong NO emissions during nights were observed when the nitrate concentration in the nutrient solution was enhanced. Then NO emissions were observed with flux densities comparable to the highest emission rates found from soils.

  14. Final Report for Regulation of Embryonic Development in Higher Plants

    Energy Technology Data Exchange (ETDEWEB)

    Harada, John J. [University of California, Davis

    2013-10-22

    The overall goal of the project was to define the cellular processes that underlie embryo development in plants at a mechanistic level. Our studies focused on a critical transcriptional regulator, Arabidopsis LEAFY COTYLEDON (LEC1), that is necessary and sufficient to induce processes required for embryo development. Because LEC1 regulates lipid accumulation during the maturation phase of embryo development, information about LEC1 may be useful in designing approaches to enhance biofuel production in plants. During the tenure of this project, we determined the molecular mechanisms by which LEC1 acts as a transcription factor in embryos. We also identified genes directly regulated by LEC1 and showed that many of these genes are involved in maturation processes. This information has been useful in dissecting the gene regulatory networks controlling embryo development. Finally, LEC1 is a novel isoform of a transcription factor that is conserved among eukaryotes, and LEC1 is active primarily in seeds. Therefore, we determined that the LEC1-type transcription factors first appeared in lycophytes during land plant evolution. Together, this study provides basic information that has implications for biofuel production.

  15. Regulation of cell division in higher plants. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Thomas W.

    2000-02-29

    Research in the latter part of the grant period was divided into two parts: (1) expansion of the macromolecular tool kit for studying plant cell division; (2) experiments in which the roles played by plant cell cycle regulators were to be cast in the light of the emerging yeast and animal cell paradigm for molecular control of the mitotic cycle. The first objectives were accomplished to a very satisfactory degree. With regard to the second part of the project, we were driven to change our objectives for two reasons. First, the families of cell cycle control genes that we cloned encoded such closely related members that the prospects for success at raising distinguishing antisera against each were sufficiently dubious as to be impractical. Epitope tagging is not feasible in Pisum sativum, our experimental system, as this species is not realistically transformable. Therefore, differentiating the roles of diverse cyclins and cyclin-dependent kinases was problematic. Secondly, our procedure for generating mitotically synchronized pea root meristems for biochemical studies was far too labor intensive for the proposed experiments. We therefore shifted our objectives to identifying connections between the conserved proteins of the cell cycle engine and factors that interface it with plant physiology and development. In this, we have obtained some very exciting results.

  16. A systematic search for positive selection in higher plants (Embryophytes

    Directory of Open Access Journals (Sweden)

    Roth Christian

    2006-06-01

    Full Text Available Abstract Background Previously, a database characterizing examples of Embryophyte gene family lineages showing evidence of positive selection was reported. Of the gene family trees, 138 Embryophyte branches showed Ka/Ks>>1 and are candidates for functional adaptation. The database and these examples have now been studied in further detail to better understand the molecular basis for plant genome evolution. Results Neutral modeling showed an excess of positive and/or negative selection in the database over a neutral expectation centered on the mean Ka/Ks ratio. Out of 673 families with assigned structures, 490 have at least one branch with Ka/Ks >>1 in a region of the protein, enabling a picture of selective pressures delineated by protein structure. Most gene families allowed reconstruction back to the last common ancestor of flowering plants (Magnoliophytes without saturation of 4- fold degenerate codon position. Positive selection occurred in a wide variety of gene families with different functions, including in the self incompatibility locus, in defense against pathogens, in embryogenesis, in cold acclimation, and in electrontransport. Structurally, selective pressures were similar between alpha-helices and beta- sheets, but were less negative and more variant on the surface and away from the hydrophobic core. Conclusion Positive selection was detected statistically significantly in a small and nonrandom minority of gene families in a systematic analysis of embryophyte gene families. More sensitive methods increased the level of positive selection that was detected and presented a structural basis for the role of positive selection in plant genomes.

  17. Conserved upstream open reading frames in higher plants

    Directory of Open Access Journals (Sweden)

    Schultz Carolyn J

    2008-07-01

    Full Text Available Abstract Background Upstream open reading frames (uORFs can down-regulate the translation of the main open reading frame (mORF through two broad mechanisms: ribosomal stalling and reducing reinitiation efficiency. In distantly related plants, such as rice and Arabidopsis, it has been found that conserved uORFs are rare in these transcriptomes with approximately 100 loci. It is unclear how prevalent conserved uORFs are in closely related plants. Results We used a homology-based approach to identify conserved uORFs in five cereals (monocots that could potentially regulate translation. Our approach used a modified reciprocal best hit method to identify putative orthologous sequences that were then analysed by a comparative R-nomics program called uORFSCAN to find conserved uORFs. Conclusion This research identified new genes that may be controlled at the level of translation by conserved uORFs. We report that conserved uORFs are rare (

  18. CBL-CIPK network for calcium signaling in higher plants

    Science.gov (United States)

    Luan, Sheng

    Plants sense their environment by signaling mechanisms involving calcium. Calcium signals are encoded by a complex set of parameters and decoded by a large number of proteins including the more recently discovered CBL-CIPK network. The calcium-binding CBL proteins specifi-cally interact with a family of protein kinases CIPKs and regulate the activity and subcellular localization of these kinases, leading to the modification of kinase substrates. This represents a paradigm shift as compared to a calcium signaling mechanism from yeast and animals. One example of CBL-CIPK signaling pathways is the low-potassium response of Arabidopsis roots. When grown in low-K medium, plants develop stronger K-uptake capacity adapting to the low-K condition. Recent studies show that the increased K-uptake is caused by activation of a specific K-channel by the CBL-CIPK network. A working model for this regulatory pathway will be discussed in the context of calcium coding and decoding processes.

  19. Transgenic tobacco plants having a higher level of methionine are more sensitive to oxidative stress.

    Science.gov (United States)

    Hacham, Yael; Matityahu, Ifat; Amir, Rachel

    2017-07-01

    Methionine is an essential amino acid the low level of which limits the nutritional quality of plants. We formerly produced transgenic tobacco (Nicotiana tabacum) plants overexpressing CYSTATHIONE γ-SYNTHASE (CGS) (FA plants), methionine's main regulatory enzyme. These plants accumulate significantly higher levels of methionine compared with wild-type (WT) plants. The aim of this study was to gain more knowledge about the effect of higher methionine content on the metabolic profile of vegetative tissue and on the morphological and physiological phenotypes. FA plants exhibit slightly reduced growth, and metabolic profiling analysis shows that they have higher contents of stress-related metabolites. Despite this, FA plants were more sensitive to short- and long-term oxidative stresses. In addition, compared with WT plants and transgenic plants expressing an empty vector, the primary metabolic profile of FA was altered less during oxidative stress. Based on morphological and metabolic phenotypes, we strongly proposed that FA plants having higher levels of methionine suffer from stress under non-stress conditions. This might be one of the reasons for their lesser ability to cope with oxidative stress when it appeared. The observation that their metabolic profiling is much less responsive to stress compared with control plants indicates that the delta changes in metabolite contents between non-stress and stress conditions is important for enabling the plants to cope with stress conditions. © 2017 Scandinavian Plant Physiology Society.

  20. Light intensity-dependent retrograde signalling in higher plants.

    Science.gov (United States)

    Szechyńska-Hebda, Magdalena; Karpiński, Stanisław

    2013-11-15

    Plants are able to acclimate to highly fluctuating light environment and evolved a short- and long-term light acclimatory responses, that are dependent on chloroplasts retrograde signalling. In this review we summarise recent evidences suggesting that the chloroplasts act as key sensors of light intensity changes in a wide range (low, high and excess light conditions) as well as sensors of darkness. They also participate in transduction and synchronisation of systemic retrograde signalling in response to differential light exposure of distinct leaves. Regulation of intra- and inter-cellular chloroplast retrograde signalling is dependent on the developmental and functional stage of the plastids. Therefore, it is discussed in following subsections: firstly, chloroplast biogenic control of nuclear genes, for example, signals related to photosystems and pigment biogenesis during early plastid development; secondly, signals in the mature chloroplast induced by changes in photosynthetic electron transport, reactive oxygen species, hormones and metabolite biosynthesis; thirdly, chloroplast signalling during leaf senescence. Moreover, with a help of meta-analysis of multiple microarray experiments, we showed that the expression of the same set of genes is regulated specifically in particular types of signals and types of light conditions. Furthermore, we also highlight the alternative scenarios of the chloroplast retrograde signals transduction and coordination linked to the role of photo-electrochemical signalling. Copyright © 2013 Elsevier GmbH. All rights reserved.

  1. Molecular insights into Zeaxanthin-dependent quenching in higher plants.

    Science.gov (United States)

    Xu, Pengqi; Tian, Lijin; Kloz, Miroslav; Croce, Roberta

    2015-09-01

    Photosynthetic organisms protect themselves from high-light stress by dissipating excess absorbed energy as heat in a process called non-photochemical quenching (NPQ). Zeaxanthin is essential for the full development of NPQ, but its role remains debated. The main discussion revolves around two points: where does zeaxanthin bind and does it quench? To answer these questions we have followed the zeaxanthin-dependent quenching from leaves to individual complexes, including supercomplexes. We show that small amounts of zeaxanthin are associated with the complexes, but in contrast to what is generally believed, zeaxanthin binding per se does not cause conformational changes in the complexes and does not induce quenching, not even at low pH. We show that in NPQ conditions zeaxanthin does not exchange for violaxanthin in the internal binding sites of the antennas but is located at the periphery of the complexes. These results together with the observation that the zeaxanthin-dependent quenching is active in isolated membranes, but not in functional supercomplexes, suggests that zeaxanthin is acting in between the complexes, helping to create/participating in a variety of quenching sites. This can explain why none of the antennas appears to be essential for NPQ and the multiple quenching mechanisms that have been observed in plants.

  2. Broadening the scope of glycosyltransferase-catalyzed sugar nucleotide synthesis.

    Science.gov (United States)

    Gantt, Richard W; Peltier-Pain, Pauline; Singh, Shanteri; Zhou, Maoquan; Thorson, Jon S

    2013-05-07

    We described the integration of the general reversibility of glycosyltransferase-catalyzed reactions, artificial glycosyl donors, and a high throughput colorimetric screen to enable the engineering of glycosyltransferases for combinatorial sugar nucleotide synthesis. The best engineered catalyst from this study, the OleD Loki variant, contained the mutations P67T/I112P/T113M/S132F/A242I compared with the OleD wild-type sequence. Evaluated against the parental sequence OleD TDP16 variant used for screening, the OleD Loki variant displayed maximum improvements in k(cat)/K(m) of >400-fold and >15-fold for formation of NDP-glucoses and UDP-sugars, respectively. This OleD Loki variant also demonstrated efficient turnover with five variant NDP acceptors and six variant 2-chloro-4-nitrophenyl glycoside donors to produce 30 distinct NDP-sugars. This study highlights a convenient strategy to rapidly optimize glycosyltransferase catalysts for the synthesis of complex sugar nucleotides and the practical synthesis of a unique set of sugar nucleotides.

  3. Effects of the Extraterrestrial Environment on Plants: Recommendations for Future Space Experiments for the MELiSSA Higher Plant Compartment

    Directory of Open Access Journals (Sweden)

    Silje A. Wolff

    2014-05-01

    Full Text Available Due to logistical challenges, long-term human space exploration missions require a life support system capable of regenerating all the essentials for survival. Higher plants can be utilized to provide a continuous supply of fresh food, atmosphere revitalization, and clean water for humans. Plants can adapt to extreme environments on Earth, and model plants have been shown to grow and develop through a full life cycle in microgravity. However, more knowledge about the long term effects of the extraterrestrial environment on plant growth and development is necessary. The European Space Agency (ESA has developed the Micro-Ecological Life Support System Alternative (MELiSSA program to develop a closed regenerative life support system, based on micro-organisms and higher plant processes, with continuous recycling of resources. In this context, a literature review to analyze the impact of the space environments on higher plants, with focus on gravity levels, magnetic fields and radiation, has been performed. This communication presents a roadmap giving directions for future scientific activities within space plant cultivation. The roadmap aims to identify the research activities required before higher plants can be included in regenerative life support systems in space.

  4. Effects of the Extraterrestrial Environment on Plants: Recommendations for Future Space Experiments for the MELiSSA Higher Plant Compartment.

    Science.gov (United States)

    Wolff, Silje A; Coelho, Liz H; Karoliussen, Irene; Jost, Ann-Iren Kittang

    2014-05-05

    Due to logistical challenges, long-term human space exploration missions require a life support system capable of regenerating all the essentials for survival. Higher plants can be utilized to provide a continuous supply of fresh food, atmosphere revitalization, and clean water for humans. Plants can adapt to extreme environments on Earth, and model plants have been shown to grow and develop through a full life cycle in microgravity. However, more knowledge about the long term effects of the extraterrestrial environment on plant growth and development is necessary. The European Space Agency (ESA) has developed the Micro-Ecological Life Support System Alternative (MELiSSA) program to develop a closed regenerative life support system, based on micro-organisms and higher plant processes, with continuous recycling of resources. In this context, a literature review to analyze the impact of the space environments on higher plants, with focus on gravity levels, magnetic fields and radiation, has been performed. This communication presents a roadmap giving directions for future scientific activities within space plant cultivation. The roadmap aims to identify the research activities required before higher plants can be included in regenerative life support systems in space.

  5. Biochemical hydrogen isotope fractionation during biosynthesis in higher plants reflects carbon metabolism of the plant

    Science.gov (United States)

    Cormier, Marc-André; Kahmen, Ansgar

    2015-04-01

    Compound-specific isotope analyses of plant material are frequently applied to understand the response of plants to the environmental changes. As it is generally assume that the main factors controlling δ2H values in plants are the plant's source water and evaporative deuterium enrichment of leaf water, hydrogen isotope analyses of plant material are mainly applied regarding hydrological conditions at different time scales. However, only few studies have directly addressed the variability of the biochemical hydrogen isotope fractionation occurring during biosynthesis of organic compounds (ɛbio), accounting also for a large part in the δ2H values of plants but generally assumed to be constant. Here we present the results from a climate-controlled growth chambers experiment where tested the sensitivity of ɛbio to different light treatments. The different light treatments were applied to induce different metabolic status (autotrophic vs. heterotrophic) in 9 different plant species that we grew from large storage organs (e.g. tubers or roots). The results show a systematic ɛbio shift (up to 80 ) between the different light treatments for different compounds (i.e. long chain n-alkanes and cellulose). We suggest that this shift is due to the different NADPH pools used by the plants to build up the compounds from stored carbohydrates in heterotrophic or autotrophic conditions. Our results have important implications for the calibration and interpretation of sedimentary and tree rings records in geological studies. In addition, as the δ2H values reflect also strongly the carbon metabolism of the plant, our findings support the idea of δ2H values as an interesting proxy for plant physiological studies.

  6. Functional Differentiation of the Glycosyltransferases That Contribute to the Chemical Diversity of Bioactive Flavonol Glycosides in Grapevines (Vitis vinifera)[W][OA

    Science.gov (United States)

    Ono, Eiichiro; Homma, Yu; Horikawa, Manabu; Kunikane-Doi, Satoshi; Imai, Haruna; Takahashi, Seiji; Kawai, Yosuke; Ishiguro, Masaji; Fukui, Yuko; Nakayama, Toru

    2010-01-01

    We identified two glycosyltransferases that contribute to the structural diversification of flavonol glycosides in grapevine (Vitis vinifera): glycosyltransferase 5 (Vv GT5) and Vv GT6. Biochemical analyses showed that Vv GT5 is a UDP-glucuronic acid:flavonol-3-O-glucuronosyltransferase (GAT), and Vv GT6 is a bifunctional UDP-glucose/UDP-galactose:flavonol-3-O-glucosyltransferase/galactosyltransferase. The Vv GT5 and Vv GT6 genes have very high sequence similarity (91%) and are located in tandem on chromosome 11, suggesting that one of these genes arose from the other by gene duplication. Both of these enzymes were expressed in accordance with flavonol synthase gene expression and flavonoid distribution patterns in this plant, corroborating their significance in flavonol glycoside biosynthesis. The determinant of the specificity of Vv GT5 for UDP-glucuronic acid was found to be Arg-140, which corresponded to none of the determinants previously identified for other plant GATs in primary structures, providing another example of convergent evolution of plant GAT. We also analyzed the determinants of the sugar donor specificity of Vv GT6. Gln-373 and Pro-19 were found to play important roles in the bifunctional specificity of the enzyme. The results presented here suggest that the sugar donor specificities of these Vv GTs could be determined by a limited number of amino acid substitutions in the primary structures of protein duplicates, illustrating the plasticity of plant glycosyltransferases in acquiring new sugar donor specificities. PMID:20693356

  7. In vitro culture of higher plants as a tool in the propagation of horticultural crops.

    NARCIS (Netherlands)

    Pierik, R.L.M.

    1988-01-01

    In vitro culture of higher plants is the culture, under sterile conditions, of plants, seeds, embryos, organs, explants, tissues, cells and protoplasts on nutrient media. This type of culture has shown spectacular development since 1975, resulting in the production and regeneration of viable

  8. Enzymatic generation of chitooligosaccharides from chitosan using soluble and immobilized glycosyltransferase (Branchzyme).

    Science.gov (United States)

    Montilla, Antonia; Ruiz-Matute, Ana I; Corzo, Nieves; Giacomini, Cecilia; Irazoqui, Gabriela

    2013-10-30

    Chitooligosaccharides possessing remarkable biological properties can be obtained by enzymatic hydrolysis of chitin. In this work, the chitosanase activity of soluble and immobilized glycosyltransferase (Branchzyme) toward chitosan and biochemical characterization are described for the first time. This enzyme was found to be homotetrameric with a molecular weight of 256 kDa, an isoelectric point of 5.3, and an optimal temperature range of between 50 and 60 °C. It was covalently immobilized to glutaraldehyde-agarose with protein and activity immobilization yields of 67% and 17%, respectively. Immobilization improved enzyme stability, increasing its half-life 5-fold, and allowed enzyme reuse for at least 25 consecutive cycles. The chitosanase activity of Branchzyme on chitosan was similar for the soluble and immobilized forms. The reaction mixture was constituted by chitooligosaccharides with degrees of polymerization of between 2 and 20, with a higher concentration having degrees of polymerization of 3-8.

  9. The comet assay in higher terrestrial plant model: Review and evolutionary trends.

    Science.gov (United States)

    Lanier, Caroline; Manier, Nicolas; Cuny, Damien; Deram, Annabelle

    2015-12-01

    The comet assay is a sensitive technique for the measurement of DNA damage in individual cells. Although it has been primarily applied to animal cells, its adaptation to higher plant tissues significantly extends the utility of plants for environmental genotoxicity research. The present review focuses on 101 key publications and discusses protocols and evolutionary trends specific to higher plants. General consensus validates the use of the percentage of DNA found in the tail, the alkaline version of the test and root study. The comet protocol has proved its effectiveness and its adaptability for cultivated plant models. Its transposition in wild plants thus appears as a logical evolution. However, certain aspects of the protocol can be improved, namely through the systematic use of positive controls and increasing the number of nuclei read. These optimizations will permit the increase in the performance of this test, namely when interpreting mechanistic and physiological phenomena. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Mechanisms of silicon-mediated alleviation of abiotic stresses in higher plants: a review.

    Science.gov (United States)

    Liang, Yongchao; Sun, Wanchun; Zhu, Yong-Guan; Christie, Peter

    2007-05-01

    Although silicon (Si) is the second most abundant element both on the surface of the Earth's crust and in soils, it has not yet been listed among the essential elements for higher plants. However, the beneficial role of Si in stimulating the growth and development of many plant species has been generally recognized. Silicon is known to effectively mitigate various abiotic stresses such as manganese, aluminum and heavy metal toxicities, and salinity, drought, chilling and freezing stresses. However, mechanisms of Si-mediated alleviation of abiotic stresses remain poorly understood. The key mechanisms of Si-mediated alleviation of abiotic stresses in higher plants include: (1) stimulation of antioxidant systems in plants, (2) complexation or co-precipitation of toxic metal ions with Si, (3) immobilization of toxic metal ions in growth media, (4) uptake processes, and (5) compartmentation of metal ions within plants. Future research needs for Si-mediated alleviation of abiotic stresses are also discussed.

  11. Structure of the Glycosyltransferase Ktr4p from Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Dominik D D Possner

    Full Text Available In the yeast Saccharomyces cerevisiae, members of the Kre2/Mnt1 protein family have been shown to be α-1,2-mannosyltransferases or α-1,2-mannosylphosphate transferases, utilising an Mn2+-coordinated GDP-mannose as the sugar donor and a variety of mannose derivatives as acceptors. Enzymes in this family are localised to the Golgi apparatus, and have been shown to be involved in both N- and O-linked glycosylation of newly-synthesised proteins, including cell wall glycoproteins. Our knowledge of the nine proteins in this family is however very incomplete at present. Only one family member, Kre2p/Mnt1p, has been studied by structural methods, and three (Ktr4p, Ktr5p, Ktr7p are completely uncharacterised and remain classified only as putative glycosyltransferases. Here we use in vitro enzyme activity assays to provide experimental confirmation of the predicted glycosyltransferase activity of Ktr4p. Using GDP-mannose as the donor, we observe activity towards the acceptor methyl-α-mannoside, but little or no activity towards mannose or α-1,2-mannobiose. We also present the structure of the lumenal catalytic domain of S. cerevisiae Ktr4p, determined by X-ray crystallography to a resolution of 2.2 Å, and the complex of the enzyme with GDP to 1.9 Å resolution.

  12. Golgi Localization of Glycosyltransferases Requires a Vps74p Oligomer

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Karl R.; Liu, Jingxuan; Li, Shiqing; Setty, Thanuja Gangi; Wood, Christopher S.; Burd, Christopher G.; Ferguson, Kathryn M. (UPENN-MED)

    2010-02-19

    The mechanism of glycosyltransferase localization to the Golgi apparatus is a long-standing question in secretory cell biology. All Golgi glycosyltransferases are type II membrane proteins with small cytosolic domains that contribute to Golgi localization. To date, no protein has been identified that recognizes the cytosolic domains of Golgi enzymes and contributes to their localization. Here, we report that yeast Vps74p directly binds to the cytosolic domains of cis and medial Golgi mannosyltransferases and that loss of this interaction correlates with loss of Golgi localization of these enzymes. We have solved the X-ray crystal structure of Vps74p and find that it forms a tetramer, which we also observe in solution. Deletion of a critical structural motif disrupts tetramer formation and results in loss of Vps74p localization and function. Vps74p is highly homologous to the human GMx33 Golgi matrix proteins, suggesting a conserved function for these proteins in the Golgi enzyme localization machinery.

  13. A strategy for characterization of persistent heteroduplex DNA in higher plants.

    Science.gov (United States)

    Dong, Chun-Bo; Mao, Jian-Feng; Suo, Yu-Jing; Shi, Le; Wang, Jun; Zhang, Ping-Dong; Kang, Xiang-Yang

    2014-10-01

    Heteroduplex DNA (hDNA) generated during homologous recombination (HR) is an important component that shapes genetic diversity in sexually reproducing organisms. However, studies of this process in higher plants are limited. This is because hDNAs are difficult to capture in higher plants as their reproductive developmental model only produces normal gametes and does not preserve the mitotic products of the post-meiotic segregation (PMS) process which is crucial for studying hDNAs. In this study, using the model system for tree and woody perennial plant biology (Populus), we propose a strategy for characterizing hDNAs in higher plants. We captured hDNAs by constructing triploid hybrids originating from a cross between unreduced 2n eggs (containing hDNA information as a result of inhibition chromosome segregation at the PMS stage) with normal male gametes. These triploid hybrids allowed us to detect the frequency and location of persistent hDNAs resulting from HR at the molecular level. We found that the frequency of persistent hDNAs, which ranged from 5.3 to 76.6%, was related to locations of the simple sequence repeat markers at the chromosomes, such as the locus-centromere distance, the surrounding DNA sequence and epigenetic information, and the richness of protein-coding transcripts at these loci. In summary, this study provides a method for characterizing persistent hDNAs in higher plants. When high-throughput sequencing techniques can be incorporated, genome-wide persistent hDNA assays for higher plants can be easily carried out using the strategy presented in this study. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  14. Aquatic food production modules in bioregenerative life support systems based on higher plants

    Science.gov (United States)

    Bluem, V.; Paris, F.

    Most bioregenerative life support systems (BLSS) are based on gravitropic higher plants which exhibit growth and seed generation disturbances in microgravity. Even when used for a lunar or martian base the reduced gravity may induce a decreased productivity in comparison to Earth. Therefore, the implementation of aquatic biomass production modules in higher plant and/or hybrid BLSS may compensate for this and offer, in addition, the possibility to produce animal protein for human nutrition. It was shown on the SLS-89 and SLS-90 space shuttle missions with the C.E.B.A.S.-MINI MODULE that the edible non gravitropic rootless higher aquatic plant Ceratophyllum demeresum exhibits an undisturbed high biomass production rate in space and that the teleost fish species, Xiphophorus helleri, adapts rapidly to space conditions without loss of its normal reproductive functions. Based on these findings a series of ground-based aquatic food production systems were developed which are disposed for utilization in space. These are plant production bioreactors for the species mentioned above and another suitable candidate, the lemnacean (duckweed) species, Wolffia arrhiza. Moreover, combined intensive aquaculture systems with a closed food loop between herbivorous fishes and aquatic and land plants are being developed which may be suitable for integration into a BLSS of higher complexity.

  15. Identification and characterization of UDP-glucose:Phloretin 4'-O-glycosyltransferase from Malus x domestica Borkh.

    Science.gov (United States)

    Yahyaa, Mosaab; Davidovich-Rikanati, Rachel; Eyal, Yoram; Sheachter, Alona; Marzouk, Sally; Lewinsohn, Efraim; Ibdah, Mwafaq

    2016-10-01

    Apples (Malus x domestica Brokh.) are among the world's most important food crops with nutritive and medicinal importance. Many of the health beneficial properties of apple fruit are suggested to be due to (poly)phenolic metabolites, including various dihydrochalcones. Although many of the genes and enzymes involved in polyphenol biosynthesis are known in many plant species, the specific reactions that lead to the biosynthesis of the sweet tasting dihydrochalcones, such as trilobatin, are unknown. To identify candidate genes for involvement in the glycosylation of dihydrochalcones, existing genome databases of the Rosaceae were screened for apple genes with significant sequence similarity to Bacillus subtilis phloretin glycosyltransferase. Herein reported is the identification and functional characterization of a Malus x domestica gene encoding phloretin-4'-O-glycosyltransferase designated MdPh-4'-OGT. Recombinant MdPh-4'-OGT protein glycosylates phloretin in the presence of UDP-glucose into trilobatin in vitro. Its apparent Km values for phloretin and UDP-glucose were 26.1 μM and 1.2 mM, respectively. Expression analysis of the MdPh-4'-OGT gene indicated that its transcript levels showed significant variation in apple tissues of different developmental stages. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Glycosyltransferases and non-alcoholic fatty liver disease

    Science.gov (United States)

    Zhan, Yu-Tao; Su, Hai-Ying; An, Wei

    2016-01-01

    Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease and its incidence is increasing worldwide. However, the underlying mechanisms leading to the development of NAFLD are still not fully understood. Glycosyltransferases (GTs) are a diverse class of enzymes involved in catalyzing the transfer of one or multiple sugar residues to a wide range of acceptor molecules. GTs mediate a wide range of functions from structure and storage to signaling, and play a key role in many fundamental biological processes. Therefore, it is anticipated that GTs have a role in the pathogenesis of NAFLD. In this article, we present an overview of the basic information on NAFLD, particularly GTs and glycosylation modification of certain molecules and their association with NAFLD pathogenesis. In addition, the effects and mechanisms of some GTs in the development of NAFLD are summarized. PMID:26937136

  17. REVIEW: The Early Application of Electrophoresis of Protein in Higher Plant Taxonomy

    Directory of Open Access Journals (Sweden)

    SURANTO

    2002-07-01

    Full Text Available The aims of this research are firstly, to study the advantages of electrophoretic techniques. Secondly, to look at the usefulness of a few mediums support of electrophoretic proteins especially the acrylamide gel. Thirdly, to examine the number of plant organs which could be used as the sources of plant proteins, and how these plants protein should be applied in the medium support that has been selected. Besides, the staining and detection procedures would be described, while the application of electrophoretic approach in higher plant taxonomy will also be evaluated. In this study we recorded that a number of taxonomic problems usually caused by morphological complexity within species can be solved using this experimental approach of electrophoresis. This method has been considered very useful in helping taxonomists making decisions.

  18. Gene expression and regulation of higher plants under soil water stress.

    Science.gov (United States)

    Ni, Fu-Tai; Chu, Li-Ye; Shao, Hong-Bo; Liu, Zeng-Hui

    2009-06-01

    Higher plants not only provide human beings renewable food, building materials and energy, but also play the most important role in keeping a stable environment on earth. Plants differ from animals in many aspects, but the important is that plants are more easily influenced by environment than animals. Plants have a series of fine mechanisms for responding to environmental changes, which has been established during their long-period evolution and artificial domestication. The machinery related to molecular biology is the most important basis. The elucidation of it will extremely and purposefully promote the sustainable utilization of plant resources and make the best use of its current potential under different scales. This molecular mechanism at least includes drought signal recognition (input), signal transduction (many cascade biochemical reactions are involved in this process), signal output, signal responses and phenotype realization, which is a multi-dimension network system and contains many levels of gene expression and regulation. We will focus on the physiological and molecular adaptive machinery of plants under soil water stress and draw a possible blueprint for it. Meanwhile, the issues and perspectives are also discussed. We conclude that biological measures is the basic solution to solving various types of issues in relation to sustainable development and the plant measures is the eventual way.

  19. Design and optimization of an experimental bioregenerative life support system with higher plants and silkworms

    Science.gov (United States)

    Hu, Enzhu; Bartsev, Sergey I.; Zhao, Ming; Liu, Professor Hong

    The conceptual scheme of an experimental bioregenerative life support system (BLSS) for planetary exploration was designed, which consisted of four elements - human metabolism, higher plants, silkworms and waste treatment. 15 kinds of higher plants, such as wheat, rice, soybean, lettuce, mulberry, et al., were selected as regenerative component of BLSS providing the crew with air, water, and vegetable food. Silkworms, which producing animal nutrition for crews, were fed by mulberry-leaves during the first three instars, and lettuce leaves last two instars. The inedible biomass of higher plants, human wastes and silkworm feces were composted into soil like substrate, which can be reused by higher plants cultivation. Salt, sugar and some household material such as soap, shampoo would be provided from outside. To support the steady state of BLSS the same amount and elementary composition of dehydrated wastes were removed periodically. The balance of matter flows between BLSS components was described by the system of algebraic equations. The mass flows between the components were optimized by EXCEL spreadsheets and using Solver. The numerical method used in this study was Newton's method.

  20. Physiological aspects of the production and conversion of DMSP in marine algae and higher plants

    NARCIS (Netherlands)

    Stefels, J

    Dimethylsulphoniopropionate (DMSP) is a compound produced in several classes of algae and higher plants that live in the marine environment. Considering its generally high intracellular concentrations, DMSP has a function in the osmotic protection of algal cells. Due to the relatively slow

  1. Diurnal adjustment in ultraviolet sunscreen protection is widespread among higher plants.

    Science.gov (United States)

    Barnes, Paul W; Flint, Stephan D; Tobler, Mark A; Ryel, Ronald J

    2016-05-01

    The accumulation of ultraviolet (UV)-absorbing compounds (flavonoids and related phenylpropanoids) in the epidermis of higher plants reduces the penetration of solar UV radiation to underlying tissues and is a primary mechanism of acclimation to changing UV conditions resulting from ozone depletion and climate change. Previously we reported that several herbaceous plant species were capable of rapid, diurnal adjustments in epidermal UV transmittance (T UV), but how widespread this phenomenon is among plants has been unknown. In the present study, we tested the generality of this response by screening 37 species of various cultivated and wild plants growing in four locations spanning a gradient of ambient solar UV and climate (Hawaii, Utah, Idaho and Louisiana). Non-destructive measurements of adaxial T UV indicated that statistically significant midday decreases in T UV occurred in 49 % of the species tested, including both herbaceous and woody growth forms, and there was substantial interspecific variation in the magnitude of these changes. In general, plants in Louisiana exhibited larger diurnal changes in T UV than those in the other locations. Moreover, across all taxa, the magnitude of these changes was positively correlated with minimum daily air temperatures but not daily UV irradiances. Results indicate that diurnal changes in UV shielding are widespread among higher plants, vary both within and among species and tend to be greatest in herbaceous plants growing in warm environments. These findings suggest that plant species differ in their UV protection "strategies" though the functional and ecological significance of this variation in UV sunscreen protection remains unclear at present.

  2. Phototolerance of lichens, mosses and higher plants in an alpine environment: analysis of photoreactions.

    Science.gov (United States)

    Heber, U; Bilger, W; Bligny, R; Lange, O L

    2000-11-01

    Adaptation to excessive light is one of the requirements of survival in an alpine environment particularly for poikilohydric organisms which in contrast to the leaves of higher plants tolerate full dehydration. Changes in modulated chlorophyll fluorescence and 820-nm absorption were investigated in the lichens Xanthoria elegans (Link) Th. Fr. and Rhizocarpon geographicum (L.) DC, in the moss Grimmia alpestris Limpr. and the higher plants Geum montanum L., Gentiana lutea L. and Pisum sativum L., all collected at altitudes higher than 2000 m above sea level. In the dehydrated state, chlorophyll fluorescence was very low in the lichens and the moss, but high in the higher plants. It increased on rehydration in the lichens and the moss, but decreased in the higher plants. Light-induced charge separation in photosystem II was indicated by pulse-induced fluorescence increases only in dried leaves, not in the dry moss and dry lichens. Strong illumination caused photodamage in the dried leaves, but not in the dry moss and dry lichens. Light-dependent increases in 820-nm absorption revealed formation of potential quenchers of chlorophyll fluorescence in all dehydrated plants, but energy transfer to quenchers decreased chlorophyll fluorescence only in the moss and the lichens, not in the higher plants. In hydrated systems, coupled cyclic electron transport is suggested to occur concurrently with linear electron transport under strong actinic illumination particularly in the lichens because far more electrons became available after actinic illumination for the reduction of photo-oxidized P700 than were available in the pool of electron carriers between photosystems II and I. In the moss Grimmia, but not in the lichens or in leaves, light-dependent quenching of chlorophyll fluorescence was extensive even under nitrogen, indicating anaerobic thylakoid acidification by persistent cyclic electron transport. In the absence of actinic illumination, acidification by ca. 8% CO2 in

  3. A web-based resource for the Arabidopsis P450, cytochromes b5, NADPH-cytochrome P450 reductases, and family 1 glycosyltransferases (http://www.P450.kvl.dk).

    Science.gov (United States)

    Paquette, Suzanne M; Jensen, Kenneth; Bak, Søren

    2009-12-01

    Gene and genome duplication is a key driving force in evolution of plant diversity. This has resulted in a number of large multi-gene families. Two of the largest multi-gene families in plants are the cytochromes P450 (P450s) and family 1 glycosyltransferases (UGTs). These two families are key players in evolution, especially of plant secondary metabolism, and in adaption to abiotic and biotic stress. In the model plant Arabidopsis thaliana there are 246 and 112 cytochromes P450 and UGTs, respectively. The Arabidopsis P450, cytochromes b(5), NADPH-cytochrome P450 reductases, and family 1 glycosyltransferases website (http://www.P450.kvl.dk) is a sequence repository of manually curated sequences, multiple sequence alignments, phylogenetic trees, sequence motif logos, 3D structures, intron-exon maps, and customized BLAST datasets.

  4. Plant species richness sustains higher trophic levels of soil nematode communities after consecutive environmental perturbations.

    Science.gov (United States)

    Cesarz, Simone; Ciobanu, Marcel; Wright, Alexandra J; Ebeling, Anne; Vogel, Anja; Weisser, Wolfgang W; Eisenhauer, Nico

    2017-07-01

    The magnitude and frequency of extreme weather events are predicted to increase in the future due to ongoing climate change. In particular, floods and droughts resulting from climate change are thought to alter the ecosystem functions and stability. However, knowledge of the effects of these weather events on soil fauna is scarce, although they are key towards functioning of terrestrial ecosystems. Plant species richness has been shown to affect the stability of ecosystem functions and food webs. Here, we used the occurrence of a natural flood in a biodiversity grassland experiment that was followed by a simulated summer drought experiment, to investigate the interactive effects of plant species richness, a natural flood, and a subsequent summer drought on nematode communities. Three and five months after the natural flooding, effects of flooding severity were still detectable in the belowground system. We found that flooding severity decreased soil nematode food-web structure (loss of K-strategists) and the abundance of plant feeding nematodes. However, high plant species richness maintained higher diversity and abundance of higher trophic levels compared to monocultures throughout the flood. The subsequent summer drought seemed to be of lower importance but reversed negative flooding effects in some cases. This probably occurred because the studied grassland system is well adapted to drought, or because drought conditions alleviated the negative impact of long-term soil waterlogging. Using soil nematodes as indicator taxa, this study suggests that high plant species richness can maintain soil food web complexity after consecutive environmental perturbations.

  5. Phylogenomic analysis of UDP glycosyltransferase 1 multigene family in Linum usitatissimum identified genes with varied expression patterns

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    Barvkar Vitthal T

    2012-05-01

    Full Text Available Abstract Background The glycosylation process, catalyzed by ubiquitous glycosyltransferase (GT family enzymes, is a prevalent modification of plant secondary metabolites that regulates various functions such as hormone homeostasis, detoxification of xenobiotics and biosynthesis and storage of secondary metabolites. Flax (Linum usitatissimum L. is a commercially grown oilseed crop, important because of its essential fatty acids and health promoting lignans. Identification and characterization of UDP glycosyltransferase (UGT genes from flax could provide valuable basic information about this important gene family and help to explain the seed specific glycosylated metabolite accumulation and other processes in plants. Plant genome sequencing projects are useful to discover complexity within this gene family and also pave way for the development of functional genomics approaches. Results Taking advantage of the newly assembled draft genome sequence of flax, we identified 137 UDP glycosyltransferase (UGT genes from flax using a conserved signature motif. Phylogenetic analysis of these protein sequences clustered them into 14 major groups (A-N. Expression patterns of these genes were investigated using publicly available expressed sequence tag (EST, microarray data and reverse transcription quantitative real time PCR (RT-qPCR. Seventy-three per cent of these genes (100 out of 137 showed expression evidence in 15 tissues examined and indicated varied expression profiles. The RT-qPCR results of 10 selected genes were also coherent with the digital expression analysis. Interestingly, five duplicated UGT genes were identified, which showed differential expression in various tissues. Of the seven intron loss/gain positions detected, two intron positions were conserved among most of the UGTs, although a clear relationship about the evolution of these genes could not be established. Comparison of the flax UGTs with orthologs from four other sequenced dicot

  6. Functional Characterization and Substrate Promiscuity of UGT71 Glycosyltransferases from Strawberry (Fragaria × ananassa).

    Science.gov (United States)

    Song, Chuankui; Gu, Le; Liu, Jingyi; Zhao, Shuai; Hong, Xiaotong; Schulenburg, Katja; Schwab, Wilfried

    2015-12-01

    Glycosylation determines the complexity and diversity of plant natural products. To characterize fruit ripening-related UDP-dependent glycosyltransferases (UGTs) functionally in strawberry, we mined the publicly available Fragaria vesca genome sequence and found 199 putative UGT genes. Candidate UGTs whose expression levels were strongly up-regulated during fruit ripening were cloned from F.×ananassa and six were successfully expressed in Escherichia coli and biochemically characterized. UGT75T1 showed very strict substrate specificity and glucosylated only galangin out of 33 compounds. The other recombinant enzymes exhibited broad substrate tolerance, accepting numerous flavonoids, hydroxycoumarins, naphthols and the plant hormone, (+)-S-abscisic acid (ABA). UGT71W2 showed the highest activity towards 1-naphthol, while UGT71A33, UGT71A34a/b and UGT71A35 preferred 3-hydroxycoumarin and formed 3- and 7-O-glucosides as well as a diglucoside from flavonols. Screening of a strawberry physiological aglycone library identified kaempferol, quercetin, ABA and three unknown natural compounds as putative in planta substrates of UGT71A33, UGT71A34a and UGT71W2. Metabolite analyses of RNA interference (RNAi)-mediated silenced fruits demonstrated that UGT71W2 contributes to the glycosylation of flavonols, xenobiotics and, to a minor extent, of ABA, in planta. The study showed that both specialist and generalist UGTs were expressed during strawberry fruit ripening and the latter were probably not restricted to only one function in plants. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  7. Sterol glycosyltransferases required for adaptation of Withania somnifera at high temperature.

    Science.gov (United States)

    Singh, Gaurav; Tiwari, Manish; Singh, Surendra P; Singh, Ruchi; Singh, Surendra; Shirke, Pramod A; Trivedi, Prabodh K; Misra, Pratibha

    2017-07-01

    Heat is a major environmental stress factor that confines growth, productivity, and metabolism of plants. Plants respond to such unfavorable conditions through changes in their physiological, biochemical and developmental processes. Withania somnifera, an important medicinal plant, grows in hot and dry conditions, however, molecular mechanisms related to such adaptive properties are not known. Here, we elucidated that members of the sterol glycosyltransferases (SGT) gene family play important roles in the survival of W. somnifera under adverse conditions through maintaining the integrity of the membrane. SGTs are enzymes involved in sterol modifications and participate in metabolic flexibility during stress. Silencing of WsSGT members, for instance WsSGTL1, WsSGTL2 and WsSGTL4, was inimical for important physiological parameters, such as electron transport rate, photochemical quantum yield, acceptor side limitation, non-photochemical quenching (NPQ), Fv/Fm and net photosynthetic rate, whereas stomatal conductance, transpiration rate and dark respiration rates (Rds) were increased. Decreased NPQ and increased Rds helped to generate significant amount of ROS in the Wsamisgt lines. After heat stress, H2 O2 , lipid peroxidation and nitric oxide production increased in the Wsamisgt lines due to high ROS generation. The expression of HSPs in Wsamisgt lines might be involved in regulation of physiological processes during stress. We have also observed increased proline accumulation which might be involved in restricting water loss in the Wsamisgt lines. Taken together, our observations revealed that SGTL enzyme activity is required to maintain the internal damages of the cell against high temperature by maintaining the sterol vs sterol glycosides ratio in the membranes of W. somnifera. © 2017 Scandinavian Plant Physiology Society.

  8. Higher plant modelling for life support applications: first results of a simple mechanistic model

    Science.gov (United States)

    Hezard, Pauline; Dussap, Claude-Gilles; Sasidharan L, Swathy

    2012-07-01

    In the case of closed ecological life support systems, the air and water regeneration and food production are performed using microorganisms and higher plants. Wheat, rice, soybean, lettuce, tomato or other types of eatable annual plants produce fresh food while recycling CO2 into breathable oxygen. Additionally, they evaporate a large quantity of water, which can be condensed and used as potable water. This shows that recycling functions of air revitalization and food production are completely linked. Consequently, the control of a growth chamber for higher plant production has to be performed with efficient mechanistic models, in order to ensure a realistic prediction of plant behaviour, water and gas recycling whatever the environmental conditions. Purely mechanistic models of plant production in controlled environments are not available yet. This is the reason why new models must be developed and validated. This work concerns the design and test of a simplified version of a mathematical model coupling plant architecture and mass balance purposes in order to compare its results with available data of lettuce grown in closed and controlled chambers. The carbon exchange rate, water absorption and evaporation rate, biomass fresh weight as well as leaf surface are modelled and compared with available data. The model consists of four modules. The first one evaluates plant architecture, like total leaf surface, leaf area index and stem length data. The second one calculates the rate of matter and energy exchange depending on architectural and environmental data: light absorption in the canopy, CO2 uptake or release, water uptake and evapotranspiration. The third module evaluates which of the previous rates is limiting overall biomass growth; and the last one calculates biomass growth rate depending on matter exchange rates, using a global stoichiometric equation. All these rates are a set of differential equations, which are integrated with time in order to provide

  9. Comparative analysis of microsatellites in chloroplast genomes of lower and higher plants.

    Science.gov (United States)

    George, Biju; Bhatt, Bhavin S; Awasthi, Mayur; George, Binu; Singh, Achuit K

    2015-11-01

    Microsatellites, or simple sequence repeats (SSRs), contain repetitive DNA sequence where tandem repeats of one to six base pairs are present number of times. Chloroplast genome sequences have been  shown to possess extensive variations in the length, number and distribution of SSRs. However, a comparative analysis of chloroplast microsatellites is not available. Considering their potential importance in generating genomic diversity, we have systematically analysed the abundance and distribution of simple and compound microsatellites in 164 sequenced chloroplast genomes from wide range of plants. The key findings of these studies are (1) a large number of mononucleotide repeats as compared to SSR(2-6)(di-, tri-, tetra-, penta-, hexanucleotide repeats) are present in all chloroplast genomes investigated, (2) lower plants such as algae show wide variation in relative abundance, density and distribution of microsatellite repeats as compared to flowering plants, (3) longer SSRs are excluded from coding regions of most chloroplast genomes, (4) GC content has a weak influence on number, relative abundance and relative density of mononucleotide as well as SSR(2-6). However, GC content strongly showed negative correlation with relative density (R (2) = 0.5, P plants possesses relatively more genomic diversity compared to higher plants.

  10. Evolutionary history and stress regulation of the lectin superfamily in higher plants

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    Ramachandran Srinivasan

    2010-03-01

    Full Text Available Abstract Background Lectins are a class of carbohydrate-binding proteins. They play roles in various biological processes. However, little is known about their evolutionary history and their functions in plant stress regulation. The availability of full genome sequences from various plant species makes it possible to perform a whole-genome exploration for further understanding their biological functions. Results Higher plant genomes encode large numbers of lectin proteins. Based on their domain structures and phylogenetic analyses, a new classification system has been proposed. In this system, 12 different families have been classified and four of them consist of recently identified plant lectin members. Further analyses show that some of lectin families exhibit species-specific expansion and rapid birth-and-death evolution. Tandem and segmental duplications have been regarded as the major mechanisms to drive lectin expansion although retrogenes also significantly contributed to the birth of new lectin genes in soybean and rice. Evidence shows that lectin genes have been involved in biotic/abiotic stress regulations and tandem/segmental duplications may be regarded as drivers for plants to adapt various environmental stresses through duplication followed by expression divergence. Each member of this gene superfamily may play specialized roles in a specific stress condition and function as a regulator of various environmental factors such as cold, drought and high salinity as well as biotic stresses. Conclusions Our studies provide a new outline of the plant lectin gene superfamily and advance the understanding of plant lectin genes in lineage-specific expansion and their functions in biotic/abiotic stress-related developmental processes.

  11. The CW domain, a structural module shared amongst vertebrates, vertebrate-infecting parasites and higher plants.

    Science.gov (United States)

    Perry, Jason; Zhao, Yunde

    2003-11-01

    A previously undetected domain, named CW for its conserved cysteine and tryptophan residues, appears to be a four-cysteine zinc-finger motif found exclusively in vertebrates, vertebrate-infecting parasites and higher plants. Of the twelve distinct nuclear protein families that comprise the CW domain-containing superfamily, only the microrchida (MORC) family has begun to be characterized. However, several families contain other domains suggesting a relationship between the CW domain and either chromatin methylation status or early embryonic development.

  12. Chemostratigraphic evidence of higher-plant evolution in the Taranaki Basin, New Zealand

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    Killops, S.D.; Raine, J.I.; Woolhouse, A.D.; Weston, R.J. [Institute of Geology and Nuclear Science, Lower Hutt (New Zealand)

    1995-05-01

    Correlation between palynological and biomarker records of higher-plant development during the Cretaceous and Paleogene in Taranaki Basin, New Zealand is good. Gymnosperms, particularly podocarps, were the chief members of coastal plain swamp flora during the Late Cretaceous, and contributed significant quantities of diterpanes, often dominated by isopimarane, to organic-rich sediments. Angiosperms increased in relative abundance through the Paleocene and became the dominant higher plants in the Eocene; their contributions to coaly sediments are characterized by various triterpanes, particularly 18 alpha(H)-oleanane and its C-24 A-ring degraded counterpart. This change in dominance of higher-land groups can be followed by the use of an angiosperm/gymnosperm index (AGI) based on the relative concentrations of selected triterpanes and diterpanes in m/z 191 and m/z 123 mass chromatograms. Plant biomarker distributions do not provide as precise age indications as do pollen assemblages, but they may be more representative of the vegetation growing in a particular area of a peat swamp.

  13. Glycosyltransferase family 43 is also found in early eukaryotes and has three subfamilies in Charophycean green algae.

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    Rahil Taujale

    Full Text Available The glycosyltransferase family 43 (GT43 has been suggested to be involved in the synthesis of xylans in plant cell walls and proteoglycans in animals. Very recently GT43 family was also found in Charophycean green algae (CGA, the closest relatives of extant land plants. Here we present evidence that non-plant and non-animal early eukaryotes such as fungi, Haptophyceae, Choanoflagellida, Ichthyosporea and Haptophyceae also have GT43-like genes, which are phylogenetically close to animal GT43 genes. By mining RNA sequencing data (RNA-Seq of selected plants, we showed that CGA have evolved three major groups of GT43 genes, one orthologous to IRX14 (IRREGULAR XYLEM14, one orthologous to IRX9/IRX9L and the third one ancestral to all land plant GT43 genes. We confirmed that land plant GT43 has two major clades A and B, while in angiosperms, clade A further evolved into three subclades and the expression and motif pattern of A3 (containing IRX9 are fairly different from the other two clades likely due to rapid evolution. Our in-depth sequence analysis contributed to our overall understanding of the early evolution of GT43 family and could serve as an example for the study of other plant cell wall-related enzyme families.

  14. Physico-chemical properties of corn starch modified with cyclodextrin glycosyltransferase.

    Science.gov (United States)

    Dura, Angela; Rosell, Cristina M

    2016-06-01

    Cyclodextrin glycosyltransferase (CGTase) has been used to produce cyclodextrins (CDs) from starches, but their ability to modify starches has been barely explored. The effect of CGTase on corn starch at sub-gelatinization temperature (50°C) and at different pH conditions, pH 4.0 and pH 6.0, was evaluated. Biochemical features, thermal and structural analysis, oligosaccharides and CDs content were studied. Microscopic analysis of the granules confirmed the enzymatic modification of the starches obtaining structures with irregular surface and small pinholes. The extent of the starch modification was largely dependent on the pHs, being higher at pH 6.0. This was also confirmed by the low viscosity of the resulting pastes during a heating and cooling cycle. Thermal parameters were not affected due to enzymatic treatment. Modified starches were less susceptible to undergo α-amylase hydrolysis. CDs released were higher for samples treated at pH 4.0. Therefore, CGTase modification of corn starches at sub-gelatinization temperature offers an attractive alternative for obtaining porous starches with different properties depending on the pH conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. The main goals of experiments with the higher plants in the project MARS - 500.

    Science.gov (United States)

    Sychev, Vladimir; Levinskikh, Margarita; Podolsky, Igor; Gushin, Vadim; Bingham, Gail; Bates, Scott

    At the present step of development of manned flight to Mars there is a current opinion that including a greenhouse in the composition of Life Support Systems (LSS) of Martian expedition would essentially improve a spacecraft habitat conditions and also would have impact to preventing of a number of possible consequences of continuous presence of human in artificial environment. Development of design objectives of future space greenhouses applicable for conditions of Martian expedition should be based, in our opinion, not only on the results of real space experiments, conducted onboard of orbital stations, but also on the results of ground-based experiments. In connection with above considerations there is a number of technological, biological and psychological experiments is planned to be conducted in the frame of MARS-500 project to resolve questions related to incorporation of higher plants in LSS of inter-planetary flights. The questions include: testing of developed elements of the greenhouse construction and methods for cultivation of vegetables under conditions of imitation of the flight of Martian expedition; selection of breeds and species of vegetables, characterized by high speed of biomass accumulation, attractive taste and appearance; investigation of growth, development and metabolism of plants under long-term continuous cultivation in manned pressurized object; comparison of the productivity of the plants as a function of utilization of different light source; determination of maximum amount of planted biomass of the plants and number of possible vegetation under conditions of long-term utilization of vegetation chamber of the greenhouse without substrate replacement; investigation of crops dietetic preferences of crew members; estimation of quality of plant biomass using seeding of the plants by microorganisms and nitrates and vitamins content as markers; development and approbation of methodical approaches to estimation of psychological factors of

  16. A role for shoot protein in shoot-root dry matter allocation in higher plants.

    Science.gov (United States)

    Andrews, M; Raven, J A; Lea, P J; Sprent, J I

    2006-01-01

    It is stated in many recent publications that nitrate (NO3-) acts as a signal to regulate dry matter partitioning between the shoot and root of higher plants. Here we challenge this hypothesis and present evidence for the viewpoint that NO3- and other environmental effects on the shoot:root dry weight ratio (S:R) of higher plants are often related mechanistically to changes in shoot protein concentration. The literature on environmental effects on S:R is reviewed, focusing on relationships between S:R, growth and leaf NO3- and protein concentrations. A series of experiments carried out to test the proposal that S:R is dependent on shoot protein concentration is highlighted and new data are presented for tobacco (Nicotiana tabacum). KEY RESULTS/EVIDENCE: Results from the literature and new data for tobacco show that S:R and leaf NO3- concentration are not significantly correlated over a range of environmental conditions. A mechanism involving the relative availability of C and N substrates for growth in shoots can explain how shoot protein concentration can influence shoot growth and hence root growth and S:R. Generally, results in the literature are compatible with the hypothesis that macronutrients, water, irradiance and CO2 affect S:R through changes in shoot protein concentration. In detailed studies on several species, including tobacco, a linear regression model incorporating leaf soluble protein concentration and plant dry weight could explain the greater proportion of the variation in S:R within and between treatments over a wide range of conditions. It is concluded that if NO3- can influence the S:R of higher plants, it does so only over a narrow range of conditions. Evidence is strong that environmental effects on S:R are often related mechanistically to their effects on shoot protein concentration.

  17. From plants to birds: higher avian predation rates in trees responding to insect herbivory.

    Directory of Open Access Journals (Sweden)

    Elina Mäntylä

    Full Text Available BACKGROUND: An understanding of the evolution of potential signals from plants to the predators of their herbivores may provide exciting examples of co-evolution among multiple trophic levels. Understanding the mechanism behind the attraction of predators to plants is crucial to conclusions about co-evolution. For example, insectivorous birds are attracted to herbivore-damaged trees without seeing the herbivores or the defoliated parts, but it is not known whether birds use cues from herbivore-damaged plants with a specific adaptation of plants for this purpose. METHODOLOGY: We examined whether signals from damaged trees attract avian predators in the wild and whether birds could use volatile organic compound (VOC emissions or net photosynthesis of leaves as cues to detect herbivore-rich trees. We conducted a field experiment with mountain birches (Betula pubescens ssp. czerepanovii, their main herbivore (Epirrita autumnata and insectivorous birds. Half of the trees had herbivore larvae defoliating trees hidden inside branch bags and half had empty bags as controls. We measured predation rate of birds towards artificial larvae on tree branches, and VOC emissions and net photosynthesis of leaves. PRINCIPAL FINDINGS AND SIGNIFICANCE: The predation rate was higher in the herbivore trees than in the control trees. This confirms that birds use cues from trees to locate insect-rich trees in the wild. The herbivore trees had decreased photosynthesis and elevated emissions of many VOCs, which suggests that birds could use either one, or both, as cues. There was, however, large variation in how the VOC emission correlated with predation rate. Emissions of (E-DMNT [(E-4,8-dimethyl-1,3,7-nonatriene], beta-ocimene and linalool were positively correlated with predation rate, while those of highly inducible green leaf volatiles were not. These three VOCs are also involved in the attraction of insect parasitoids and predatory mites to herbivore-damaged plants

  18. Molecular Evolution of the Glycosyltransferase 6 Gene Family in Primates

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    Eliane Evanovich

    2016-01-01

    Full Text Available Glycosyltransferase 6 gene family includes ABO, Ggta1, iGb3S, and GBGT1 genes and by three putative genes restricted to mammals, GT6m6, GTm6, and GT6m7, only the latter is found in primates. GT6 genes may encode functional and nonfunctional proteins. Ggta1 and GBGT1 genes, for instance, are pseudogenes in catarrhine primates, while iGb3S gene is only inactive in human, bonobo, and chimpanzee. Even inactivated, these genes tend to be conversed in primates. As some of the GT6 genes are related to the susceptibility or resistance to parasites, we investigated (i the selective pressure on the GT6 paralogs genes in primates; (ii the basis of the conservation of iGb3S in human, chimpanzee, and bonobo; and (iii the functional potential of the GBGT1 and GT6m7 in catarrhines. We observed that the purifying selection is prevalent and these genes have a low diversity, though ABO and Ggta1 genes have some sites under positive selection. GT6m7, a putative gene associated with aggressive periodontitis, may have regulatory function, but experimental studies are needed to assess its function. The evolutionary conservation of iGb3S in humans, chimpanzee, and bonobo seems to be the result of proximity to genes with important biological functions.

  19. Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

    Science.gov (United States)

    Yang, Lin-Tong; Qi, Yi-Ping; Jiang, Huan-Xin; Chen, Li-Song

    2013-01-01

    Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H+-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed. PMID:23509687

  20. Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

    Directory of Open Access Journals (Sweden)

    Lin-Tong Yang

    2013-01-01

    Full Text Available Approximately 30% of the world’s total land area and over 50% of the world’s potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a anion channels or transporters, (b internal concentrations of OA anions in plant tissues, (d temperature, (e root plasma membrane (PM H+-ATPase, (f magnesium (Mg, and (e phosphorus (P. Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed.

  1. Formation of higher plant component microbial community in closed ecological system

    Science.gov (United States)

    Tirranen, L. S.

    2001-07-01

    Closed ecological systems (CES) place at the disposal of a researcher unique possibilities to study the role of microbial communities in individual components and of the entire system. The microbial community of the higher plant component has been found to form depending on specific conditions of the closed ecosystem: length of time the solution is reused, introduction of intrasystem waste water into the nutrient medium, effect of other component of the system, and system closure in terms of gas exchange. The higher plant component formed its own microbial complex different from that formed prior to closure. The microbial complex of vegetable polyculture is more diverse and stable than the monoculture of wheat. The composition of the components' microflora changed, species diversity decreased, individual species of bacteria and fungi whose numbers were not so great before the closure prevailed. Special attention should be paid to phytopathogenic and conditionally pathogenic species of microorganisms potentially hazardous to man or plants and the least controlled in CES. This situation can endanger creation of CES and make conjectural existence of preplanned components, man, specifically, and consequently, of CES as it is.

  2. Regulation of photosynthesis by ion channels in cyanobacteria and higher plants.

    Science.gov (United States)

    Checchetto, Vanessa; Teardo, Enrico; Carraretto, Luca; Formentin, Elide; Bergantino, Elisabetta; Giacometti, Giorgio Mario; Szabo, Ildiko

    2013-12-01

    Photosynthesis converts light energy into chemical energy, and supplies ATP and NADPH for CO2 fixation into carbohydrates and for the synthesis of several compounds which are essential for autotrophic growth. Oxygenic photosynthesis takes place in thylakoid membranes of chloroplasts and photosynthetic prokaryote cyanobacteria. An ancestral photoautotrophic prokaryote related to cyanobacteria has been proposed to give rise to chloroplasts of plants and algae through an endosymbiotic event. Indeed, photosynthetic complexes involved in the electron transport coupled to H(+) translocation and ATP synthesis are similar in higher plants and cyanobacteria. Furthermore, some of the protein and solute/ion conducting machineries also share common structure and function. Electrophysiological and biochemical evidence support the existence of ion channels in the thylakoid membrane in both types of organisms. By allowing specific ion fluxes across thylakoid membranes, ion channels have been hypothesized to either directly or indirectly regulate photosynthesis, by modulating the proton motive force. Recent molecular identification of some of the thylakoid-located channels allowed to obtain genetic proof in favor of such hypothesis. Furthermore, some ion channels of the envelope membrane in chloroplasts have also been shown to impact on this light-driven process. Here we give an overview of thylakoid/chloroplast located ion channels of higher plants and of cyanobacterium Synechocystis sp. PCC 6803. We focus on channels shown to be implicated in the regulation of photosynthesis and discuss the possible mechanisms of action. © 2013 Elsevier B.V. All rights reserved.

  3. Composition, architecture and dynamics of the photosynthetic apparatus in higher plants.

    Science.gov (United States)

    Nevo, Reinat; Charuvi, Dana; Tsabari, Onie; Reich, Ziv

    2012-04-01

    The process of oxygenic photosynthesis enabled and still sustains aerobic life on Earth. The most elaborate form of the apparatus that carries out the primary steps of this vital process is the one present in higher plants. Here, we review the overall composition and supramolecular organization of this apparatus, as well as the complex architecture of the lamellar system within which it is harbored. Along the way, we refer to the genetic, biochemical, spectroscopic and, in particular, microscopic studies that have been employed to elucidate the structure and working of this remarkable molecular energy conversion device. As an example of the highly dynamic nature of the apparatus, we discuss the molecular and structural events that enable it to maintain high photosynthetic yields under fluctuating light conditions. We conclude the review with a summary of the hypotheses made over the years about the driving forces that underlie the partition of the lamellar system of higher plants and certain green algae into appressed and non-appressed membrane domains and the segregation of the photosynthetic protein complexes within these domains. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

  4. Regulation of chloroplast number and DNA synthesis in higher plants. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mullet, J.E.

    1995-11-10

    The long term objective of this research is to understand the process of chloroplast development and its coordination with leaf development in higher plants. This is important because the photosynthetic capacity of plants is directly related to leaf and chloroplast development. This research focuses on obtaining a detailed description of leaf development and the early steps in chloroplast development including activation of plastid DNA synthesis, changes in plastid DNA copy number, activation of chloroplast transcription and increases in plastid number per cell. The grant will also begin analysis of specific biochemical mechanisms by isolation of the plastid DNA polymerase, and identification of genetic mutants which are altered in their accumulation of plastid DNA and plastid number per cell.

  5. Regulation of chloroplast number and DNA synthesis in higher plants. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mullet, J.E.

    1995-11-10

    The long term objective of this research is to understand the process of chloroplast development and its coordination with leaf development in higher plants. This is important because the photosynthetic capacity of plants is directly related to leaf and chloroplast development. This research focuses on obtaining a detailing description of leaf development and the early steps in chloroplast development including activation of plastid DNA synthesis, changes in plastid DNA copy number, activation of chloroplast transcription and increases in plastid number per cell. The grant will also begin analysis of specific biochemical mechanisms by isolation of the plastid DNA polymerase, and identification of genetic mutants which are altered in their accumulation of plastid DNA and plastid number per cell.

  6. Extractive bioconversion of cyclodextrins by Bacillus cereus cyclodextrin glycosyltransferase in aqueous two-phase system.

    Science.gov (United States)

    Ng, Hui Suan; Ooi, Chien Wei; Mokhtar, Mohd Noriznan; Show, Pau Loke; Ariff, Arbakariya; Tan, Joo Shun; Ng, Eng-Poh; Ling, Tau Chuan

    2013-08-01

    An extractive bioconversion with Bacillus cereus cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) in aqueous two-phase system (ATPS) was investigated for the synthesis and recovery of cyclodextrins (CDs). Optimum condition for the extractive bioconversion of CDs was achieved in ATPS consisted of 7.7% (w/w) polyethylene glycol (PEG) 20,000 and 10.3% (w/w) dextran T500 with volume ratio (VR) of 4.0. Enzymatic conversion of starch occurred mainly in dextran-rich bottom phase whereas the product, CDs was transferred to top phase and a higher partition coefficient of CDs was achieved. Repetitive batch of CDs synthesis was employed by replenishment of the top phase components and addition of starch every 8h. An average total CDs concentration of 13.7 mg/mL, (4.77 mg/mLα-CD, 5.02 mg/mLβ-CD and 3.91 mg/mLγ-CD) was recovered in the top phase of PEG 20,000/dextran T500 ATPS. This study showed the effectiveness of ATPS application in extractive bioconversion of CDs synthesis with B. cereus CGTase. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Studies on the chalcone synthase gene of two higher plants: petroselinum hortense and matthiola incana

    Energy Technology Data Exchange (ETDEWEB)

    Hemleben, V.; Frey, M.; Rall, S.; Koch, M.; Kittel, M.; Kreuzaler, F.; Ragg, H.; Fautz, E.; Hahlbrock, K.

    1982-01-01

    Two higher plant systems are presented which allow to study coordinated gene expression of the light-induced metabolic pathway of flavonoid biosynthesis: tissue culture cells of Petroselinum hortense (Apiaceae) and different developmental stages of various genotypes of Matthiola incana (Brassicaceae). The gene structure of the chalcone synthase is mainly studied. A cDNA clone (pLF56) of parsley has been constructed and characterized conferring the chalcone synthase gene sequence. Strong cross hybridization between the parsley cDNA and Matthiola DNA allowed to identify a HindIII fragment (6000 bp) identical in size for parsley and different Matthiola wild type lines and a mutant line.

  8. Interference of Cd2+ in functioning of the photosynthetic apparatus of higher plants

    Directory of Open Access Journals (Sweden)

    Tadeusz Baszyński

    2014-01-01

    Full Text Available The actual opinions concerning the role of Cd2+ in inhibition of photosynthesis have been reviewed. The light phase of photosynthesis, particularly the site of Cd2+ action in the photosynthetic transport chain has been given the greatest attention. Cd2+-induced inhibition of Photosystem II activity as the result of thylakoid membrane degradation has been discussed. The present studies on Cd2+-inhibited dark reactions occurring in stroma has been analysed. Attention has been drawn to the fact that the results of studies in vitro are not always compatible with the changes found in the photosynthetic apparatus of higher plants growing in a Cd2 containing medium.

  9. Seed sprout production: Consumables and a foundation for higher plant growth in space

    Science.gov (United States)

    Day, Michelle; Thomas, Terri; Johnson, Steve; Luttges, Marvin

    1990-01-01

    Seed sprouts can be produced as a source of fresh vegetable materials and as higher plant seedlings in space. Sprout production was undertaken to evaluate the mass accumulations possible, the technologies needed, and the reliability of the overall process. Baseline experiments corroborated the utility of sprout production protocols for a variety of seed types. The automated delivery of saturated humidity effectively supplants labor intensive manual soaking techniques. Automated humidification also lend itself to modest centrifugal sprout growth environments. A small amount of ultraviolet radiation effectively suppressed bacterial and fungal contamination, and the sprouts were suitable for consumption.

  10. Studies on the chalcone synthase gene of two higher plants: petroselinum hortense and matthiola incana.

    Science.gov (United States)

    Hemleben, V; Frey, M; Rall, S; Koch, M; Kittel, M; Kreuzaler, F; Ragg, H; Fautz, E; Hahlbrock, K

    1982-01-01

    Two higher plant systems are presented which allow to study coordinated gene expression of the light-induced metabolic pathway of flavonoid biosynthesis: tissue culture cells of Petroselinum hortense (Apiaceae) and different developmental stages of various genotypes of Matthiola incana (Brassicaceae). The gene structure of the chalcone synthase is mainly studied. A cDNA clone (pLF56) of parsley has been constructed and characterized conferring the chalcone synthase gene sequence. Strong cross hybridization between the parsley cDNA and Matthiola DNA allowed to identify a HindIII fragment (6000 bp) identical in size for parsley and different Matthiola wild type lines and a mutant line.

  11. Role of Aquaporins in Determining Carbon and Nitrogen Status in Higher Plants

    Directory of Open Access Journals (Sweden)

    Limin Gao

    2018-01-01

    Full Text Available Aquaporins (AQPs are integral membrane proteins facilitating the transport of water and some small neutral molecules across cell membranes. In past years, much effort has been made to reveal the location of AQPs as well as their function in water transport, photosynthetic processes, and stress responses in higher plants. In the present review, we paid attention to the character of AQPs in determining carbon and nitrogen status. The role of AQPs during photosynthesis is characterized as its function in transporting water and CO2 across the membrane of chloroplast and thylakoid; recalculated results from published studies showed that over-expression of AQPs contributed to 25% and 50% increases in stomatal conductance (gs and mesophyll conductance (gm, respectively. The nitrogen status in plants is regulated by AQPs through their effect on water flow as well as urea and NH4+ uptake, and the potential role of AQPs in alleviating ammonium toxicity is discussed. At the same time, root and/or shoot AQP expression is quite dependent on both N supply amounts and forms. Future research directions concerning the function of AQPs in regulating plant carbon and nitrogen status as well as C/N balance are also highlighted.

  12. Influence of gaseous contaminants in the atmosphere of ISS on growth and development of higher plants

    Science.gov (United States)

    Levinskikh, Margarita; Sychev, Vladimir; Podolsky, Igor; Moukhamedieva, Lana; Gostimskiy, Sergey; Bingham, Gail

    Continues exploitation of pressurized manned objects revealed that artificial gaseous atmosphere is a multi-component mixture containing adverse micro-dirt consisted of 14 classes of chemical compounds (Moukhamedieva, 2003). Dynamics of descendant process depend on duration of pressurized object utilization, resources of life support (e.g. level of closeness), parameters of microclimate and experimental tasks conducted by a crew. Previously it was shown that composition of gas environment of the space station remarkably altered growth and development of higher plants (Levinskikh et al., 2000). Specifically, it was found that the main changes in productivity and morphometric characteristics of the spaceflight plants of superdwarf wheat were caused by phytotoxic effect of ethylene (1,1-2,0 mg/m3) in the atmosphere of MIR orbital station. From 2003 to April, 2007 we have conducted 7 experiments focused on cultivation of dwarf peas in space greenhouse LADA onboard International Space Station (ISS-6-10, 12, 14). Results of the first 5 experiments showed that characteristics of growth and development of the peas planted in the space greenhouse had no differences if compared with ground control variants. In the similar experiments with peas during ISS-12 and ISS-14 it was found that total and seed productions of the plants were lower than ones of the previous experiments and ones of the ground controls. Cytological analysis of roots of the space seeds for the first time revealed significant increase of chromosomal aberrations in comparison with laboratory controls Analysis of total contamination of the atmosphere of the ISS by gaseous dirt showed consistent (starting from ISS-11) increasing of the toxicity coefficient (Kt). W e suppose that the accumulation of pollutant in the atmosphere of ISS is the main reason causing general decreasing of productivity and increasing of the number of chromosomal aberrations in the peas cultivated in space greenhouse LADA at the stage

  13. Using simple donors to drive the equilibria of glycosyltransferase-catalyzed reactions.

    Science.gov (United States)

    Gantt, Richard W; Peltier-Pain, Pauline; Cournoyer, William J; Thorson, Jon S

    2011-08-21

    We report that simple glycoside donors can drastically shift the equilibria of glycosyltransferase-catalyzed reactions, transforming NDP-sugar formation from an endothermic to an exothermic process. To demonstrate the utility of this thermodynamic adaptability, we highlight the glycosyltransferase-catalyzed synthesis of 22 sugar nucleotides from simple aromatic sugar donors, as well as the corresponding in situ formation of sugar nucleotides as a driving force in the context of glycosyltransferase-catalyzed reactions for small-molecule glycodiversification. These simple aromatic donors also enabled a general colorimetric assay for glycosyltransfer, applicable to drug discovery, protein engineering and other fundamental sugar nucleotide-dependent investigations. This study directly challenges the general notion that NDP-sugars are 'high-energy' sugar donors when taken out of their traditional biological context.

  14. Biochemical and molecular characterization of a flavonoid 3-O-glycosyltransferase responsible for anthocyanins and flavonols biosynthesis in Freesia hybrida

    Directory of Open Access Journals (Sweden)

    Wei eSun

    2016-03-01

    Full Text Available The glycosylation of flavonoids increases their solubility and stability in plants. Flowers accumulate anthocyanidin and flavonol glycosides which are synthesized by UDP-sugar flavonoid glycosyltransferases (UFGTs. In our previous study, a cDNA clone (Fh3GT1 encoding UFGT was isolated from Freesia hybrida, which was preliminarily proved to be invovled in cyanidin 3-O-glucoside biosynthesis. Here, a variety of anthocyanin and flavonol glycosides were detected in flowers and other tissues of F. hybrida, implying the versatile roles of Fh3GT1 in flavonoids biosynthesis. To further unravel its multi-functional roles, integrative analysis between gene expression and metabolites was investigated. The results showed expression of Fh3GT1 was positively related to the accumulation of anthocyanins and flavonol glycosides, suggesting its potential roles in the biosynthesis of both flavonoid glycosides. Subsequently, biochemical analysis results revealed that a broad range of flavonoid substrates including flavonoid not naturally occurred in F. hybrida could be recognized by the recombinant Fh3GT1. Both UDP-glucose and UDP-galactose could be used as sugar donors by recombinant Fh3GT1, although UDP-galactose was transferred with relatively low activity. Furthermore, regiospecificity analysis demonstrated that Fh3GT1 was able to glycosylate delphinidin at the 3-, 4'- and 7- positions in a sugar-dependent manner. And the introduction of Fh3GT1 into Arabidopsis UGT78D2 mutant successfully restored the anthocyanins and flavonols phenotypes caused by lost-of-function of the 3GT, indicating that Fh3GT1 functions as a flavonoid 3-O-glucosyltransferase in vivo. In summary, these results demonstrate that Fh3GT1 is a flavonoid 3-O-glycosyltransferase using UDP-glucose as the preferred sugar donor and may involve in flavonoid glycosylation in F. hybrida.

  15. Biochemical and Molecular Characterization of a Flavonoid 3-O-glycosyltransferase Responsible for Anthocyanins and Flavonols Biosynthesis in Freesia hybrida.

    Science.gov (United States)

    Sun, Wei; Liang, Lingjie; Meng, Xiangyu; Li, Yueqing; Gao, Fengzhan; Liu, Xingxue; Wang, Shucai; Gao, Xiang; Wang, Li

    2016-01-01

    The glycosylation of flavonoids increases their solubility and stability in plants. Flowers accumulate anthocyanidin and flavonol glycosides which are synthesized by UDP-sugar flavonoid glycosyltransferases (UFGTs). In our previous study, a cDNA clone (Fh3GT1) encoding UFGT was isolated from Freesia hybrida, which was preliminarily proved to be invovled in cyanidin 3-O-glucoside biosynthesis. Here, a variety of anthocyanin and flavonol glycosides were detected in flowers and other tissues of F. hybrida, implying the versatile roles of Fh3GT1 in flavonoids biosynthesis. To further unravel its multi-functional roles, integrative analysis between gene expression and metabolites was investigated. The results showed expression of Fh3GT1 was positively related to the accumulation of anthocyanins and flavonol glycosides, suggesting its potential roles in the biosynthesis of both flavonoid glycosides. Subsequently, biochemical analysis results revealed that a broad range of flavonoid substrates including flavonoid not naturally occurred in F. hybrida could be recognized by the recombinant Fh3GT1. Both UDP-glucose and UDP-galactose could be used as sugar donors by recombinant Fh3GT1, although UDP-galactose was transferred with relatively low activity. Furthermore, regiospecificity analysis demonstrated that Fh3GT1 was able to glycosylate delphinidin at the 3-, 4-', and 7- positions in a sugar-dependent manner. And the introduction of Fh3GT1 into Arabidopsis UGT78D2 mutant successfully restored the anthocyanins and flavonols phenotypes caused by lost-of-function of the 3GT, indicating that Fh3GT1 functions as a flavonoid 3-O-glucosyltransferase in vivo. In summary, these results demonstrate that Fh3GT1 is a flavonoid 3-O-glycosyltransferase using UDP-glucose as the preferred sugar donor and may involve in flavonoid glycosylation in F. hybrida.

  16. Roles of Predicted Glycosyltransferases in the Biosynthesis of the Rhizobium etli CE3 O Antigen

    Science.gov (United States)

    Ojeda, Kristylea J.; Simonds, Laurie

    2013-01-01

    The Rhizobium etli CE3 O antigen is a fixed-length heteropolymer. The genetic regions required for its synthesis have been identified, and the nucleotide sequences are known. The structure of the O antigen has been determined, but the roles of specific genes in synthesizing this structure are relatively unclear. Within the known O-antigen genetic clusters of this strain, nine open reading frames (ORFs) were found to contain a conserved glycosyltransferase domain. Each ORF was mutated, and the resulting mutant lipopolysaccharide (LPS) was analyzed. Tricine SDS-PAGE revealed stepwise truncations of the O antigen that were consistent with differences in mutant LPS sugar compositions and reactivity with O-antigen-specific monoclonal antibodies. Based on these results and current theories of O-antigen synthesis, specific roles were deduced for each of the nine glycosyltransferases, and a model for biosynthesis of the R. etli CE3 O antigen was proposed. In this model, O-antigen biosynthesis is initiated with the addition of N-acetyl-quinovosamine-phosphate (QuiNAc-P) to bactoprenol-phosphate by glycosyltransferase WreU. Glycosyltransferases WreG, WreE, WreS, and WreT would each act once to attach mannose, fucose, a second fucose, and 3-O-methyl-6-deoxytalose (3OMe6dTal), respectively. WreH would then catalyze the addition of methyl glucuronate (MeGlcA) to complete the first instance of the O-antigen repeat unit. Four subsequent repeats of this unit composed of fucose, 3OMe6dTal, and MeGlcA would be assembled by a cycle of reactions catalyzed by two additional glycosyltransferases, WreM and WreL, along with WreH. Finally, the O antigen would be capped by attachment of di- or tri-O-methylated fucose as catalyzed by glycosyltransferase WreB. PMID:23435981

  17. Contribution of PsbS Function and Stomatal Conductance to Foliar Temperature in Higher Plants.

    Science.gov (United States)

    Kulasek, Milena; Bernacki, Maciej Jerzy; Ciszak, Kamil; Witoń, Damian; Karpiński, Stanisław

    2016-07-01

    Natural capacity has evolved in higher plants to absorb and harness excessive light energy. In basic models, the majority of absorbed photon energy is radiated back as fluorescence and heat. For years the proton sensor protein PsbS was considered to play a critical role in non-photochemical quenching (NPQ) of light absorbed by PSII antennae and in its dissipation as heat. However, the significance of PsbS in regulating heat emission from a whole leaf has never been verified before by direct measurement of foliar temperature under changing light intensity. To test its validity, we here investigated the foliar temperature changes on increasing and decreasing light intensity conditions (foliar temperature dynamics) using a high resolution thermal camera and a powerful adjustable light-emitting diode (LED) light source. First, we showed that light-dependent foliar temperature dynamics is correlated with Chl content in leaves of various plant species. Secondly, we compared the foliar temperature dynamics in Arabidopsis thaliana wild type, the PsbS null mutant npq4-1 and a PsbS-overexpressing transgenic line under different transpiration conditions with or without a photosynthesis inhibitor. We found no direct correlations between the NPQ level and the foliar temperature dynamics. Rather, differences in foliar temperature dynamics are primarily affected by stomatal aperture, and rapid foliar temperature increase during irradiation depends on the water status of the leaf. We conclude that PsbS is not directly involved in regulation of foliar temperature dynamics during excessive light energy episodes. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  18. Bacterial origin of a diverse family of UDP-glycosyltransferase genes in the Tetranychus urticae genome.

    Science.gov (United States)

    Ahn, Seung-Joon; Dermauw, Wannes; Wybouw, Nicky; Heckel, David G; Van Leeuwen, Thomas

    2014-07-01

    UDP-glycosyltransferases (UGTs) catalyze the conjugation of a variety of small lipophilic molecules with uridine diphosphate (UDP) sugars, altering them into more water-soluble metabolites. Thereby, UGTs play an important role in the detoxification of xenobiotics and in the regulation of endobiotics. Recently, the genome sequence was reported for the two-spotted spider mite, Tetranychus urticae, a polyphagous herbivore damaging a number of agricultural crops. Although various gene families implicated in xenobiotic metabolism have been documented in T. urticae, UGTs so far have not. We identified 80 UGT genes in the T. urticae genome, the largest number of UGT genes in a metazoan species reported so far. Phylogenetic analysis revealed that lineage-specific gene expansions increased the diversity of the T. urticae UGT repertoire. Genomic distribution, intron-exon structure and structural motifs in the T. urticae UGTs were also described. In addition, expression profiling after host-plant shifts and in acaricide resistant lines supported an important role for UGT genes in xenobiotic metabolism. Expanded searches of UGTs in other arachnid species (Subphylum Chelicerata), including a spider, a scorpion, two ticks and two predatory mites, unexpectedly revealed the complete absence of UGT genes. However, a centipede (Subphylum Myriapoda) and a water flea and a crayfish (Subphylum Crustacea) contain UGT genes in their genomes similar to insect UGTs, suggesting that the UGT gene family might have been lost early in the Chelicerata lineage and subsequently re-gained in the tetranychid mites. Sequence similarity of T. urticae UGTs and bacterial UGTs and their phylogenetic reconstruction suggest that spider mites acquired UGT genes from bacteria by horizontal gene transfer. Our findings show a unique evolutionary history of the T. urticae UGT gene family among other arthropods and provide important clues to its functions in relation to detoxification and thereby host

  19. Effects of ion pairing with calcium and magnesium on selenate availability to higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Parker, D.R.; Tice, K.R.; Thomason, D.N. [Univ. of California, Riverside, CA (United States). Dept. of Soil and Environmental Sciences

    1997-03-01

    The effects of solution speciation on the bioavailability of trace metals are well documented, but the role of speciation in the bioavailability of oxyanionic trace elements that may form significant ion pairs with Ca and Mg in saline media has not been investigated. The authors assessed the effects of such ion pairing on the availability of selenate to representative monocotyledonous and dicotyledonous higher plants. Formation constants for the CaSO{sub 4}{sup 0} formation was confirmed, but the value of 10{sup 2.7} for CaSeO{sub 4}{sup 0} was found to be in error; a value of 10{sup 2.0} is proposed here as the correct formation constant. Five solution culture experiments were conducted using alfalfa (Medicago sativa L.) or tall wheatgrass (Elytrigia pontica [Podp.] Holub) with treatments consisting of NaSeO{sub 4} levels in combination with various levels of MgCl{sub 2} or CaCl{sub 2}. Both shoot Se concentrations and whole-plant Se contents were highly correlated with the free SeO{sub 4}{sup 2{minus}} activity but were poorly correlated with the sum of the free ion plus Ca and Mg ion pair species. Thus, the authors have shown, for the first time, that the free ion model of trace metal bioavailability is also valid for oxyanions that form complexes with Ca and Mg in saline media but that this conclusion hinges critically on the accuracy of the pertinent formation constants.

  20. Functional differences between galactolipids and glucolipids revealed in photosynthesis of higher plants.

    Science.gov (United States)

    Hölzl, Georg; Witt, Sandra; Kelly, Amélie A; Zähringer, Ulrich; Warnecke, Dirk; Dörmann, Peter; Heinz, Ernst

    2006-05-09

    Galactolipids represent the most abundant lipid class in thylakoid membranes, where oxygenic photosynthesis is performed. The identification of galactolipids at specific sites within photosynthetic complexes by x-ray crystallography implies specific roles for galactolipids during photosynthetic electron transport. The preference for galactose and not for the more abundant sugar glucose in thylakoid lipids and their specific roles in photosynthesis are not understood. Introduction of a bacterial glucosyltransferase from Chloroflexus aurantiacus into the galactolipid-deficient dgd1 mutant of Arabidopsis thaliana resulted in the accumulation of a glucose-containing lipid in the thylakoids. At the same time, the growth defect of the dgd1 mutant was complemented. However, the degree of trimerization of light-harvesting complex II and the photosynthetic quantum yield of transformed dgd1 plants were only partially restored. These results indicate that specific interactions of the galactolipid head group with photosynthetic protein complexes might explain the preference for galactose in thylakoid lipids of higher plants. Therefore, galactose in thylakoid lipids can be exchanged with glucose without severe effects on growth, but the presence of galactose is crucial to maintain maximal photosynthetic efficiency.

  1. Growth and development in higher plants under simulated microgravity conditions on a 3-dimensional clinostat

    Science.gov (United States)

    Shimazu, T.; Yuda, T.; Miyamoto, K.; Yamashita, M.; Ueda, J.

    Growth and development of etiolated pea (Pisum sativum L. cv. Alaska) and maize (Zea mays L. cv. Golden Cross Bantam) seedlings grown under simulated microgravity conditions were intensively studied using a 3-dimensional clinostat as a simulator of weightlessness. Epicotyls of etiolated pea seedlings grown on the clinostat were the most oriented toward the direction far from cotyledons. Mesocotyls of etiolated maize seedlings grew at random and coleoptiles curved slightly during clinostat rotation. Clinostat rotation promoted the emergence of the 3rd internodes in etiolated pea seedlings, while it significantly inhibited the growth of the 1st internodes. In maize seedlings, the growth of coleoptiles was little affected by clinostat rotation, but that of mesocotyls was suppressed, and therefore, the emergence of the leaf out of coleoptile was promoted. Clinostat rotation reduced the osmotic concentration in the 1st internodes of pea seedlings, although it has little effect on the 2nd and the 3rd internodes. Clinostat rotation also reduced the osmotic concentrations in both coleoptiles and mesocotyls of maize seedlings. Cell-wall extensibilities of the 1st and the 3rd internodes of pea seedlings grown on the clinostat were significantly lower and higher as compared with those on 1 g conditions, respectively. Cell-wall extensibility of mesocotyls in seedlings grown on the clinostat also decreased. Changes in cell wall properties seem to be well correlated to the growth of each organ in pea and maize seedlings. These results suggest that the growth and development of plants is controlled under gravity on earth, and that the growth responses of higher plants to microgravity conditions are regulated by both cell-wall mechanical properties and osmotic properties of stem cells.

  2. Expression and occurrence of uracil-DNA glycosylase in higher plants.

    Science.gov (United States)

    Bones, Atle M

    1993-08-01

    Uracil-DNA glycosylase (UDG) is the first enzyme in the base excision repair pathway for removal of uracil in DNA. DNA repair capacity is likely to be a critical factor in mutagenesis and thereby in the capacity to prevent genetic damage and unwanted variation. We have studied expression of UDG in 9 higher plant species. The highest expression of UDG was measured in Solanum tuberosum. A comparison of 6 Solanum tuberosum cultivars showed that the specific activity ranged from 30 pmol mg1 protein min-1 in the cultivar Laila to 80 pmol mg-1 protein min-1 in the cultivar Ostara. Measurement of UDG in Begonia X cheimantha gave no indications of enzyme activity. The possible effects of no or low UDG activity is discussed. In vitro cultures of Solanum tuberosum and Thymus vulgaris were used to examine the effect of auxin and cytokinin on the UDG activity. Axillary shoots of Solanum tuberosum were cultured on medium including 20 variations in hormone concentration. Auxin (1-naphtaleneacetic acid) increased the expression of UDG. Plants cultured on medium supplemented with 3 mg 1-1 1-naphtaleneacetic acid showed a specific UDG activity which was approximately 3-fold higher than the activity in controls. The cytokinin benzyladenine reduced the specific UDG activity at concentrations in the range 0.25-10 mg 1-1 . In vitro cultured Saintpaulia ionantha was used to examine UDG activity during initiation, conditioning and multiplication cycles. In general, highest expression of UDG was measured in the conditioning cycle on hormone free medium. Measurement of UDG expression during single subculture periods, clearly showed that UDG expression may vary over one culture period. Expression of UDG was in general highest three weeks after transfer to fresh medium. Of different seedling organs from 0- to 15-day-old Brassica napus L., roots and hypocotyls showed the highest UDG activities. In cotyledons a very low and nearly constant specific activity was observed. In 12-day

  3. The Drosophila gene brainiac encodes a glycosyltransferase putatively involved in glycosphingolipid synthesis

    DEFF Research Database (Denmark)

    Schwientek, Tilo; Keck, Birgit; Levery, Steven B

    2002-01-01

    The Drosophila genes fringe and brainiac exhibit sequence similarities to glycosyltransferases. Drosophila and mammalian fringe homologs encode UDP-N-acetylglucosamine:fucose-O-Ser beta1,3-N-acetylglucosaminyltransferases that modulate the function of Notch family receptors. The biological functi...

  4. Mutations converting cyclodextrin glycosyltransferase from a transglycosylase into a starch hydrolase

    NARCIS (Netherlands)

    Leemhuis, Hans; Dijkstra, Bauke W.; Dijkhuizen, Lubbert

    2002-01-01

    Cyclodextrin glycosyltransferase (CGTase) efficiently catalyzes transglycosylation of oligo-maltodextrins, although the enzyme also has a low hydrolytic activity. Its +2 substrate binding subsite, which contains the conserved Phe184 and Phe260 residues, has been shown to be important for this

  5. Rational Design of Cyclodextrin Glycosyltransferase from Bacillus circulans Strain 251 to Increase α-Cyclodextrin Production

    NARCIS (Netherlands)

    Veen, Bart A. van der; Uitdehaag, Joost C.M.; Penninga, Dirk; Alebeek, Gert-Jan W.M. van; Smith, Loraine M.; Dijkstra, Bauke W.; Dijkhuizen, Lubbert

    2000-01-01

    Cyclodextrin glycosyltransferases (CGTase) (EC 2.4.1.19) are extracellular bacterial enzymes that generate cyclodextrins from starch. All known CGTases produce mixtures of α, β, and γ-cyclodextrins. A maltononaose inhibitor bound to the active site of the CGTase from Bacillus circulans strain 251

  6. Rational design of cyclodextrin glycosyltransferase from Bacillus circulans strain 251 to increase alpha-cyclodextrin production

    NARCIS (Netherlands)

    Uitdehaag, JCM; Penninga, D; van Alebeek, GJWM; Smith, LM; Dijkstra, BW; Dijkhuizen, L

    2000-01-01

    Cyclodextrin glycosyltransferases (CGTase) (EC;2.4.1.19) are extracellular bacterial enzymes that generate cyclodextrins from starch. All known CGTases produce mixtures of alpha, beta, and gamma-cyclodextrins. A maltononaose inhibitor bound to the active site of the CGTase from Bacillus circulans

  7. Bacterial origin of a diverse family of UDP-glycosyltransferase genes in the Tetranychus urticae genome

    NARCIS (Netherlands)

    Ahn, S.J.; Dermauw, W.; Wybouw, N.; Heckel, D.G.; Van Leeuwen, T.

    2014-01-01

    UDP-glycosyltransferases (UGTs) catalyze the conjugation of a variety of small lipophilic molecules with uridine diphosphate (UDP) sugars, altering them into more water-soluble metabolites. Thereby, UGTs play an important role in the detoxification of xenobiotics and in the regulation of

  8. Localization of small heat shock proteins to the higher plant endomembrane system.

    Science.gov (United States)

    Helm, K W; LaFayette, P R; Nagao, R T; Key, J L; Vierling, E

    1993-01-01

    Three related gene families of low-molecular-weight (LMW) heat shock proteins (HSPs) have been characterized in plants. We describe a fourth LMW HSP family, represented by PsHSP22.7 from Pisum sativum and GmHSP22.0 from Glycine max, and demonstrate that this family of proteins is endomembrane localized. PsHSP22.7 and GmHSP22.0 are 76.7% identical at the amino acid level. Both proteins have amino-terminal signal peptides and carboxyl-terminal sequences characteristic of endoplasmic reticulum (ER) retention signals. The two proteins closely resemble class I cytoplasmic LMW HSPs, suggesting that they evolved from the cytoplasmic proteins through the addition of the signal peptide and ER retention motif. The endomembrane localization of these proteins was confirmed by cell fractionation. The polypeptide product of PsHSP22.7 mRNA was processed to a smaller-M(r) form by canine pancreatic microsomes; in vivo, GmHSP22.0 polysomal mRNA was found to be predominantly membrane bound. In vitro-processed PsHSP22.7 corresponded in mass and pI to one of two proteins detected in ER fractions from heat-stressed plants by using anti-PsHSP22.7 antibodies. Like other LMW HSPs, PsHSP22.7 was observed in higher-molecular-weight structures with apparent masses of between 80 and 240 kDa. The results reported here indicate that members of this new class of LMW HSPs are most likely resident ER proteins and may be similar in function to related LMW HSPs in the cytoplasm. Along with the HSP90 and HSP70 classes of HSPs, this is the third category of HSPs localized to the ER.

  9. Optimization of animal manure vermicomposting based on biomass production of earthworms and higher plants.

    Science.gov (United States)

    Borges, Yan V; Alves, Luciano; Bianchi, Ivan; Espíndola, Jonas C; Oliveira, Juahil M De; Radetski, Claudemir M; Somensi, Cleder A

    2017-11-02

    The goal of this study was to optimize the mixture of swine manure (SM) and cattle manure (CM) used in the vermicomposting process, seeking to increase the manure biodegradation rate and enhance the biomass production of both earthworms and higher plants. To achieve this goal, physico-chemical parameters were determined to assess the final compost quality after 50 days of vermicomposting. The different manure ratios used to produce the composts (C) were as follows (SM:CM, % m/m basis): C1 100:0, C2 (75:25), C3 (50:50), C4 (25:75), and C5 (0:100). In addition, the earthworm biomass and the phytoproductivity of lettuce (Lactuca sativa L.) plants grown in mixtures (1:1) of natural soil and the most viable vermicomposts were investigated. The C1 and C2 compost compositions were associated with high earthworm mortality rates. The C3 compost provided the highest mineral concentrations and C5 showed the highest lettuce yield (wet biomass). The results verify that stabilized cattle manure is an excellent substrate for the vermicomposting process and that fresh swine manure must be mixed with pre-stabilized cattle manure to ensure an optimized vermicomposting process, which must be controlled in terms of temperature and ammonia levels. It is concluded that small livestock farmers could add value to swine manure by applying the vermicomposting process, without the need for high investments and with a minimal requirement for management of the biodegradation process. These are important technical aspects to be considered when circular economy principles are applied to small farms.

  10. Genome-wide analysis of UDP-glycosyltransferase super family in Brassica rapa and Brassica oleracea reveals its evolutionary history and functional characterization.

    Science.gov (United States)

    Yu, Jingyin; Hu, Fan; Dossa, Komivi; Wang, Zhaokai; Ke, Tao

    2017-06-23

    Glycosyltransferases comprise a highly divergent and polyphyletic multigene family that is involved in widespread modification of plant secondary metabolites in a process called glycosylation. According to conserved domains identified in their amino acid sequences, these glycosyltransferases can be classified into a single UDP-glycosyltransferase (UGT) 1 superfamily. We performed genome-wide comparative analysis of UGT genes to trace evolutionary history in algae, bryophytes, pteridophytes, and angiosperms; then, we further investigated the expansion mechanisms and function characterization of UGT gene families in Brassica rapa and Brassica oleracea. Using Hidden Markov Model search, we identified 3, 21, 140, 200, 115, 147, and 147 UGTs in Chlamydomonas reinhardtii, Physcomitrella patens, Selaginella moellendorffii, Oryza sativa, Arabidopsis thaliana, B. rapa, and B. oleracea, respectively. Phylogenetic analysis revealed that UGT80 gene family is an ancient gene family, which is shared by all plants and UGT74 gene family is shared by ferns and angiosperms, but the remaining UGT gene families were shared by angiosperms. In dicot lineage, UGTs among three species were classified into three subgroups containing 3, 6, and 12 UGT gene families. Analysis of chromosomal distribution indicates that 98.6 and 71.4% of UGTs were located on B. rapa and B. oleracea pseudo-molecules, respectively. Expansion mechanism analyses uncovered that whole genome duplication event exerted larger influence than tandem duplication on expansion of UGT gene families in B. rapa, and B. oleracea. Analysis of selection forces of UGT orthologous gene pairs in B. rapa, and B. oleracea compared to A. thaliana suggested that orthologous genes in B. rapa, and B. oleracea have undergone negative selection, but there were no significant differences between A. thaliana -B. rapa and A. thaliana -B. oleracea lineages. Our comparisons of expression profiling illustrated that UGTs in B. rapa performed more

  11. Identification of a root-specific glycosyltransferase from Arabidopsis ...

    Indian Academy of Sciences (India)

    SEARCH U

    stress such as water or salt stress, by the expression of a gene that confers tolerance in a part of the plant such as the root, which is especially important with respect to that stress. Root-specific promoters also have the potential for application in the engineering of plants to improve uptake of nutrients through root tissues.

  12. The three transglycosylation reactions catalyzed by cyclodextrin glycosyltransferase from Bacillus circulans (strain 251) proceed via different kinetic mechanisms

    NARCIS (Netherlands)

    Veen, Bart A. van der; Alebeek, Gert-Jan W.M. van; Uitdehaag, Joost C.M.; Dijkstra, Bauke W.; Dijkhuizen, Lubbert

    Cyclodextrin glycosyltransferase (CGTase) catalyzes three transglycosylation reactions via a double displacement mechanism involving a covalent enzyme-intermediate complex (substituted-enzyme intermediate). Characterization of the three transglycosylation reactions, however, revealed that they

  13. Atomistic insight into the catalytic mechanism of glycosyltransferases by combined quantum mechanics/molecular mechanics (QM/MM) methods.

    Science.gov (United States)

    Tvaroška, Igor

    2015-02-11

    Glycosyltransferases catalyze the formation of glycosidic bonds by assisting the transfer of a sugar residue from donors to specific acceptor molecules. Although structural and kinetic data have provided insight into mechanistic strategies employed by these enzymes, molecular modeling studies are essential for the understanding of glycosyltransferase catalyzed reactions at the atomistic level. For such modeling, combined quantum mechanics/molecular mechanics (QM/MM) methods have emerged as crucial. These methods allow the modeling of enzymatic reactions by using quantum mechanical methods for the calculation of the electronic structure of the active site models and treating the remaining enzyme environment by faster molecular mechanics methods. Herein, the application of QM/MM methods to glycosyltransferase catalyzed reactions is reviewed, and the insight from modeling of glycosyl transfer into the mechanisms and transition states structures of both inverting and retaining glycosyltransferases are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Research on the effects of altered gravity and other factors on the growth and development of higher plants

    Science.gov (United States)

    Brown, A. H.

    1973-01-01

    The establishment, maintenance and use of the NASA-UCSC Botanical Centrifuge is discussed. The broad goals of this project were: (1) to establish facilities for conducting experiments under conditions of sustained centrifugation; (2) to pursue research on the gravitational physiology of higher plants; (3) to develop experimental hardware suitable for studies of plant development in the weightless condition; and (4) to accommodate visiting investigators whose researches are of interest to the NASA Biomedical Program and who may require for some limited time, the use of a medium size centrifuge with associated facilities appropriate for plant physiological studies.

  15. Production characteristics of the "higher plants-soil-like substrate" system as an element of the bioregenerative life support system

    Science.gov (United States)

    Velichko, V. V.; Tikhomirov, A. A.; Ushakova, S. A.; Tikhomirova, N. A.; Shihov, V. N.; Tirranen, L. S.; Gribovskaya, I. A.

    2013-01-01

    The study addresses the possibility of long-duration operation of a higher plant conveyor, using a soil-like substrate (SLS) as the root zone. Chufa (Cyperus esculentus L.), radish (Raphanus sativus L.), and lettuce (Lactuca sativa L.) were used as study material. A chufa community consisting of 4 age groups and radish and lettuce communities consisting of 2 age groups were irrigated with a nutrient solution, which contained mineral elements extracted from the SLS. After each harvest, inedible biomass of the harvested plants and inedible biomasses of wheat and saltwort were added to the SLS. The amounts of the inedible biomasses of wheat and saltwort to be added to the SLS were determined based on the nitrogen content of the edible mass of harvested plants. CO2 concentration in the growth chamber was maintained within the range of 1100-1700 ppm. The results of the study show that higher plants can be grown quite successfully using the proposed process of plant waste utilization in the SLS. The addition of chufa inedible biomass to the SLS resulted in species-specific inhibition of growth of both cultivated crops and microorganisms in the "higher plants - SLS" system. There were certain differences between the amounts of some mineral elements removed from the SLS with the harvested edible biomass and those added to it with the inedible biomasses of wheat and saltwort.

  16. Aluminum, a Friend or Foe of Higher Plants in Acid Soils

    Science.gov (United States)

    Bojórquez-Quintal, Emanuel; Escalante-Magaña, Camilo; Echevarría-Machado, Ileana; Martínez-Estévez, Manuel

    2017-01-01

    Aluminum (Al) is the most abundant metal in the earth’s crust, but its availability depends on soil pH. Despite this abundance, Al is not considered an essential element and so far no experimental evidence has been put forward for a biological role. In plants and other organisms, Al can have a beneficial or toxic effect, depending on factors such as, metal concentration, the chemical form of Al, growth conditions and plant species. Here we review recent advances in the study of Al in plants at physiological, biochemical and molecular levels, focusing mainly on the beneficial effect of Al in plants (stimulation of root growth, increased nutrient uptake, the increase in enzyme activity, and others). In addition, we discuss the possible mechanisms involved in improving the growth of plants cultivated in soils with acid pH, as well as mechanisms of tolerance to the toxic effect of Al. PMID:29075280

  17. Two Novel Fungal Phenolic UDP Glycosyltransferases from Absidia coerulea and Rhizopus japonicus.

    Science.gov (United States)

    Xie, Kebo; Dou, Xiaoxiang; Chen, Ridao; Chen, Dawei; Fang, Cheng; Xiao, Zhiyan; Dai, Jungui

    2017-04-15

    In the present study, two novel phenolic UDP glycosyltransferases (P-UGTs), UGT58A1 and UGT59A1, which can transfer sugar moieties from active donors to phenolic acceptors to generate corresponding glycosides, were identified in the fungal kingdom. UGT58A1 (from Absidia coerulea ) and UGT59A1 (from Rhizopus japonicas ) share a low degree of homology with known UGTs from animals, plants, bacteria, and viruses. These two P-UGTs are membrane-bound proteins with an N-terminal signal peptide and a transmembrane domain at the C terminus. Recombinant UGT58A1 and UGT59A1 are able to regioselectively and stereoselectively glycosylate a variety of phenolic aglycones to generate the corresponding glycosides. Phylogenetic analysis revealed the novelty of UGT58A1 and UGT59A1 in primary sequences in that they are distantly related to other UGTs and form a totally new evolutionary branch. Moreover, UGT58A1 and UGT59A1 represent the first members of the UGT58 and UGT59 families, respectively. Homology modeling and mutational analysis implied the sugar donor binding sites and key catalytic sites, which provided insights into the catalytic mechanism of UGT58A1. These results not only provide an efficient enzymatic tool for the synthesis of bioactive glycosides but also create a starting point for the identification of P-UGTs from fungi at the molecular level. IMPORTANCE Thus far, there have been many reports on the glycosylation of phenolics by fungal cells. However, no P-UGTs have ever been identified in fungi. Our study identified fungal P-UGTs at the molecular level and confirmed the existence of the UGT58 and UGT59 families. The novel sequence information on UGT58A1 and UGT59A1 shed light on the exciting and new P-UGTs hiding in the fungal kingdom, which would lead to the characterization of novel P-UGTs from fungi. Molecular identification of fungal P-UGTs not only is theoretically significant for a better understanding of the evolution of UGT families but also can be applied

  18. Carotenoids in certain higher plants from various ecological niches of Egypt

    Directory of Open Access Journals (Sweden)

    B. Czeczuga

    2015-01-01

    Full Text Available The carotenoids content in Posidonia oceanica, Nelumbium nuciferum, Opuntia ficus-indica and Zygophyllum album from different ecological niches in Egypt was studied. Considerable differences, both qualitative and quantitative among four investigated plant species were found.

  19. Zinc oxide and silver nanoparticles influence the antioxidative status in a higher aquatic plant, Spirodela punctata

    CSIR Research Space (South Africa)

    Thwala, Melusi

    2012-09-01

    Full Text Available during the 14-d exposure. The biochemical anti-oxidative status of the plant specimens were investigated using quantitative analysis of total antioxidant capacity, peroxidase and activity of catalase and superoxide dismutase. The anti-oxidative defence...

  20. Molecular Properties and Functional Divergence of the Dehydroascorbate Reductase Gene Family in Lower and Higher Plants.

    Directory of Open Access Journals (Sweden)

    Yuan-Jie Zhang

    Full Text Available Dehydroascorbate reductase (DHAR, which reduces oxidized ascorbate, is important for maintaining an appropriate ascorbate redox state in plant cells. To date, genome-wide molecular characterization of DHARs has only been conducted in bryophytes (Physcomitrella patens and eudicots (e.g. Arabidopsis thaliana. In this study, to gain a general understanding of the molecular properties and functional divergence of the DHARs in land plants, we further conducted a comprehensive analysis of DHARs from the lycophyte Selaginella moellendorffii, gymnosperm Picea abies and monocot Zea mays. DHARs were present as a small gene family in all of the land plants we examined, with gene numbers ranging from two to four. All the plants contained cytosolic and chloroplastic DHARs, indicating dehydroascorbate (DHA can be directly reduced in the cytoplasm and chloroplast by DHARs in all the plants. A novel vacuolar DHAR was found in Z. mays, indicating DHA may also be reduced in the vacuole by DHARs in Z. mays. The DHARs within each species showed extensive functional divergence in their gene structures, subcellular localizations, and enzymatic characteristics. This study provides new insights into the molecular characteristics and functional divergence of DHARs in land plants.

  1. A complete mitochondrial genome of wheat (Triticum aestivum cv. Chinese Yumai), and fast evolving mitochondrial genes in higher plants.

    Science.gov (United States)

    Cui, Peng; Liu, Huitao; Lin, Qiang; Ding, Feng; Zhuo, Guoyin; Hu, Songnian; Liu, Dongcheng; Yang, Wenlong; Zhan, Kehui; Zhang, Aimin; Yu, Jun

    2009-12-01

    Plant mitochondrial genomes, encoding necessary proteins involved in the system of energy production, play an important role in the development and reproduction of the plant. They occupy a specific evolutionary pattern relative to their nuclear counterparts. Here, we determined the winter wheat (Triticum aestivum cv. Chinese Yumai) mitochondrial genome in a length of 452 and 526 bp by shotgun sequencing its BAC library. It contains 202 genes, including 35 known protein-coding genes, three rRNA and 17 tRNA genes, as well as 149 open reading frames (ORFs; greater than 300 bp in length). The sequence is almost identical to the previously reported sequence of the spring wheat (T. aestivum cv. Chinese Spring); we only identified seven SNPs (three transitions and four transversions) and 10 indels (insertions and deletions) between the two independently acquired sequences, and all variations were found in non-coding regions. This result confirmed the accuracy of the previously reported mitochondrial sequence of the Chinese Spring wheat. The nucleotide frequency and codon usage of wheat are common among the lineage of higher plant with a high AT-content of 58%. Molecular evolutionary analysis demonstrated that plant mitochondrial genomes evolved at different rates, which may correlate with substantial variations in metabolic rate and generation time among plant lineages. In addition, through the estimation of the ratio of non-synonymous to synonymous substitution rates between orthologous mitochondrion-encoded genes of higher plants, we found an accelerated evolutionary rate that seems to be the result of relaxed selection.

  2. Production characteristics of lettuce Lactuca sativa L. in the frame of the first crop tests in the Higher Plant Chamber integrated into the MELiSSA Pilot Plant

    Science.gov (United States)

    Tikhomirova, Natalia; Lawson, Jamie; Stasiak, Michael; Dixon, Mike; Paille, Christel; Peiro, Enrique; Fossen, Arnaud; Godia, Francesc

    Micro-Ecological Life Support System Alternative (MELiSSA) is an artificial closed ecosystem that is considered a tool for the development of a bioregenerative life support system for manned space missions. One of the five compartments of MELiSSA loop -Higher Plant Chamber was recently integrated into the MELiSSA Pilot Plant facility at Universitat Aut`noma deo Barcelona. The main contributions expected by integration of this photosynthetic compartment are oxygen, water, vegetable food production and CO2 consumption. Production characteristics of Lactuca sativa L., as a MELiSSA candidate crop, were investigated in this work in the first crop experiments in the MELiSSA Pilot Plant facility. The plants were grown in batch culture and totaled 100 plants with a growing area 5 m long and 1 m wide in a sealed controlled environment. Several replicates of the experiments were carried out with varying duration. It was shown that after 46 days of lettuce cultivation dry edible biomass averaged 27, 2 g per plant. However accumulation of oxygen in the chamber, which required purging of the chamber, and decrease in the food value of the plants was observed. Reducing the duration of the tests allowed uninterrupted test without opening the system and also allowed estimation of the crop's carbon balance. Results of productivity, tissue composition, nutrient uptake and canopy photosynthesis of lettuce regardless of test duration are discussed in the paper.

  3. Improved plant nitrogen nutrition contributes to higher water use efficiency in tomatoes under alternate partial root-zone irrigation

    DEFF Research Database (Denmark)

    Wang, Yaosheng; Liu, Fulai; Andersen, Mathias Neumann

    2010-01-01

    carbon isotope composition (δ13C), indicating that the improvement of WUE might have been a result of long-term optimisation of stomatal control over gas exchange. The constantly higher xylem sap ABA concentration in PRI compared with DI plants was seemingly responsible for the greater control over......Comparative effects of partial root-zone irrigation (PRI) and deficit irrigation (DI) on stomatal conductance (gs), nitrogen accumulation and distribution in tomato (Lycopersicon esculentum L.) plants were investigated in a split-root pot experiment. Results showed that both PRI and DI saved 25...... nutrition and distribution in the canopy may indicate that PRI plants have a greater photosynthetic capacity than DI plants; this is confirmed by the observed positive linear relationship between specific leaf N content and δ13C. It is concluded that PRI improves N nutrition and optimises N distribution...

  4. The evolutionary reality of species and higher taxa in plants: a survey of post-modern opinion and evidence.

    Science.gov (United States)

    Barraclough, Timothy G; Humphreys, Aelys M

    2015-07-01

    Species are normally considered to be the fundamental unit for understanding the evolution of biodiversity. Yet, in a survey of botanists in 1940, twice as many felt that plant genera were more natural units than plant species. Revisiting the survey, we found more people now regarded species as a more evolutionarily real unit, but a sizeable number still felt that genera were more evolutionarily real than species. Definitions of 'evolutionarily real' split into those based on shared evolutionary history and those based on shared evolutionary fate via ongoing evolutionary processes. We discuss recent work testing for shared evolutionary fate at the species and higher levels and present preliminary evidence for evolutionarily significant higher taxa in plants. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  5. Some remarks on the methods of assessing the population density of higher plants in cases of aggregated spatial structure

    Directory of Open Access Journals (Sweden)

    Anna Justyna Kwiatkowska

    2015-01-01

    Full Text Available This paper presents a comparative analysis of the methods used for. assessing the density of higher plants. The analysis was carried out on natural population (Vaccinium myrtillus L. characterized by aggregated spatial structure. Attention has been paid to the surface methods with high (0.25 m2 and low

  6. Silencing of sterol glycosyltransferases modulates the withanolide biosynthesis and leads to compromised basal immunity of Withania somnifera.

    Science.gov (United States)

    Singh, Gaurav; Tiwari, Manish; Singh, Surendra Pratap; Singh, Surendra; Trivedi, Prabodh Kumar; Misra, Pratibha

    2016-05-05

    Sterol glycosyltransferases (SGTs) catalyse transfer of glycon moiety to sterols and their related compounds to produce diverse glyco-conjugates or steryl glycosides with different biological and pharmacological activities. Functional studies of SGTs from Withania somnifera indicated their role in abiotic stresses but details about role under biotic stress are still unknown. Here, we have elucidated the function of SGTs by silencing SGTL1, SGTL2 and SGTL4 in Withania somnifera. Down-regulation of SGTs by artificial miRNAs led to the enhanced accumulation of withanolide A, withaferin A, sitosterol, stigmasterol and decreased content of withanoside V in Virus Induced Gene Silencing (VIGS) lines. This was further correlated with increased expression of WsHMGR, WsDXR, WsFPPS, WsCYP710A1, WsSTE1 and WsDWF5 genes, involved in withanolide biosynthesis. These variations of withanolide concentrations in silenced lines resulted in pathogen susceptibility as compared to control plants. The infection of Alternaria alternata causes increased salicylic acid, callose deposition, superoxide dismutase and H2O2 in aMIR-VIGS lines. The expression of biotic stress related genes, namely, WsPR1, WsDFS, WsSPI and WsPR10 were also enhanced in aMIR-VIGS lines in time dependent manner. Taken together, our observations revealed that a positive feedback regulation of withanolide biosynthesis occurred by silencing of SGTLs which resulted in reduced biotic tolerance.

  7. Differentiating moss from higher plants is critical in studying the carbon cycle of the boreal biome.

    Science.gov (United States)

    Yuan, Wenping; Liu, Shuguang; Dong, Wenjie; Liang, Shunlin; Zhao, Shuqing; Chen, Jingming; Xu, Wenfang; Li, Xianglan; Barr, Alan; Andrew Black, T; Yan, Wende; Goulden, Mike L; Kulmala, Liisa; Lindroth, Anders; Margolis, Hank A; Matsuura, Yojiro; Moors, Eddy; van der Molen, Michiel; Ohta, Takeshi; Pilegaard, Kim; Varlagin, Andrej; Vesala, Timo

    2014-06-26

    The satellite-derived normalized difference vegetation index (NDVI), which is used for estimating gross primary production (GPP), often includes contributions from both mosses and vascular plants in boreal ecosystems. For the same NDVI, moss can generate only about one-third of the GPP that vascular plants can because of its much lower photosynthetic capacity. Here, based on eddy covariance measurements, we show that the difference in photosynthetic capacity between these two plant functional types has never been explicitly included when estimating regional GPP in the boreal region, resulting in a substantial overestimation. The magnitude of this overestimation could have important implications regarding a change from a current carbon sink to a carbon source in the boreal region. Moss abundance, associated with ecosystem disturbances, needs to be mapped and incorporated into GPP estimates in order to adequately assess the role of the boreal region in the global carbon cycle.

  8. SIGNIFICANCE OF GALACTINOL AND RAFFINOSE FAMILY OLIGOSACCHARIDE SYNTHESIS IN PLANTS

    Directory of Open Access Journals (Sweden)

    Sonali eSengupta

    2015-08-01

    Full Text Available Abiotic stress induces differential expression of genes responsible for the synthesis of Raffinose series of Oligosaccharides (RFOs in plants. RFOs are described as the most widespread D-galactose containing oligosaccharides in higher plants. Biosynthesis of RFOs begin with the activity of Galactinol synthase (GolS; EC 2.4.1.123, a GT8 family glycosyltransferase that galactosylates myo-inositol to produce galactinol. Raffinose and the subsequent higher molecular weight RFOs (Stachyose, Verbascose and Ajugose are synthesized from sucrose by the subsequent addition of activated galactose moieties donated by Galactinol. Interestingly, GolS, the key enzyme of this pathway is functional only in the flowering plants. It is thus assumed that RFO synthesis is a specialized metabolic event in higher plants; although it is not known whether lower plant groups synthesize any galactinol or RFOs. In higher plants, several functional importance of RFOs have been reported, e.g. RFOs protect the embryo from maturation associated desiccation, are predominant transport carbohydrate in some plant families, act as signaling molecule following pathogen attack and wounding and accumulate in vegetative tissues in response to a range of abiotic stresses. However, the loss-of-function mutants reported so far fail to show any perturbation in those biological functions. The role of RFOs in biotic and abiotic stress is therefore still in debateand their specificity and related components remains to be demonstrated. The present review discusses the biology and stress-linked regulation of this less studied extension of inositol metabolic pathway.

  9. Congruence and Diversity of Butterfly-Host Plant Associations at Higher Taxonomic Levels

    Science.gov (United States)

    Ferrer-Paris, José R.; Sánchez-Mercado, Ada; Viloria, Ángel L.; Donaldson, John

    2013-01-01

    We aggregated data on butterfly-host plant associations from existing sources in order to address the following questions: (1) is there a general correlation between host diversity and butterfly species richness?, (2) has the evolution of host plant use followed consistent patterns across butterfly lineages?, (3) what is the common ancestral host plant for all butterfly lineages? The compilation included 44,148 records from 5,152 butterfly species (28.6% of worldwide species of Papilionoidea) and 1,193 genera (66.3%). The overwhelming majority of butterflies use angiosperms as host plants. Fabales is used by most species (1,007 spp.) from all seven butterfly families and most subfamilies, Poales is the second most frequently used order, but is mostly restricted to two species-rich subfamilies: Hesperiinae (56.5% of all Hesperiidae), and Satyrinae (42.6% of all Nymphalidae). We found a significant and strong correlation between host plant diversity and butterfly species richness. A global test for congruence (Parafit test) was sensitive to uncertainty in the butterfly cladogram, and suggests a mixed system with congruent associations between Papilionidae and magnoliids, Hesperiidae and monocots, and the remaining subfamilies with the eudicots (fabids and malvids), but also numerous random associations. The congruent associations are also recovered as the most probable ancestral states in each node using maximum likelihood methods. The shift from basal groups to eudicots appears to be more likely than the other way around, with the only exception being a Satyrine-clade within the Nymphalidae that feed on monocots. Our analysis contributes to the visualization of the complex pattern of interactions at superfamily level and provides a context to discuss the timing of changes in host plant utilization that might have promoted diversification in some butterfly lineages. PMID:23717448

  10. Congruence and diversity of butterfly-host plant associations at higher taxonomic levels.

    Directory of Open Access Journals (Sweden)

    José R Ferrer-Paris

    Full Text Available We aggregated data on butterfly-host plant associations from existing sources in order to address the following questions: (1 is there a general correlation between host diversity and butterfly species richness?, (2 has the evolution of host plant use followed consistent patterns across butterfly lineages?, (3 what is the common ancestral host plant for all butterfly lineages? The compilation included 44,148 records from 5,152 butterfly species (28.6% of worldwide species of Papilionoidea and 1,193 genera (66.3%. The overwhelming majority of butterflies use angiosperms as host plants. Fabales is used by most species (1,007 spp. from all seven butterfly families and most subfamilies, Poales is the second most frequently used order, but is mostly restricted to two species-rich subfamilies: Hesperiinae (56.5% of all Hesperiidae, and Satyrinae (42.6% of all Nymphalidae. We found a significant and strong correlation between host plant diversity and butterfly species richness. A global test for congruence (Parafit test was sensitive to uncertainty in the butterfly cladogram, and suggests a mixed system with congruent associations between Papilionidae and magnoliids, Hesperiidae and monocots, and the remaining subfamilies with the eudicots (fabids and malvids, but also numerous random associations. The congruent associations are also recovered as the most probable ancestral states in each node using maximum likelihood methods. The shift from basal groups to eudicots appears to be more likely than the other way around, with the only exception being a Satyrine-clade within the Nymphalidae that feed on monocots. Our analysis contributes to the visualization of the complex pattern of interactions at superfamily level and provides a context to discuss the timing of changes in host plant utilization that might have promoted diversification in some butterfly lineages.

  11. Engineering plastid fatty acid biosynthesis to improve food quality and biofuel production in higher plants.

    Science.gov (United States)

    Rogalski, Marcelo; Carrer, Helaine

    2011-06-01

    The ability to manipulate plant fatty acid biosynthesis by using new biotechnological approaches has allowed the production of transgenic plants with unusual fatty acid profile and increased oil content. This review focuses on the production of very long chain polyunsaturated fatty acids (VLCPUFAs) and the increase in oil content in plants using molecular biology tools. Evidences suggest that regular consumption of food rich in VLCPUFAs has multiple positive health benefits. Alternative sources of these nutritional fatty acids are found in cold-water fishes. However, fish stocks are in severe decline because of decades of overfishing, and also fish oils can be contaminated by the accumulation of toxic compounds. Recently, there is also an increase in oilseed use for the production of biofuels. This tendency is partly associated with the rapidly rising costs of petroleum, increased concern about the environmental impact of fossil oil and the attractive need to develop renewable sources of fuel. In contrast to this scenario, oil derived from crop plants is normally contaminant free and less environmentally aggressive. Genetic engineering of the plastid genome (plastome) offers a number of attractive advantages, including high-level foreign protein expression, marker-gene excision and transgene containment because of maternal inheritance of plastid genome in most crops. Here, we describe the possibility to improve fatty acid biosynthesis in plastids, production of new fatty acids and increase their content in plants by genetic engineering of plastid fatty acid biosynthesis via plastid transformation. © 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

  12. Zinc oxide and silver nanoparticles influence the antioxidative status in a higher aquatic plant, Spirodela punctata

    CSIR Research Space (South Africa)

    Thwala, Melusi

    2012-09-01

    Full Text Available The authors present evidence of free radical activity and resultant anti-oxidative defence in Spirodela plants after exposure to 0.01-1000 mg/L of ZnO and Ag nanoparticles (NPs) over 96-h and 14-d. The quantification of reactive nitrogen...

  13. Differentiating moss from higher plants is critical in studying the carbon cycle of the boreal biome

    DEFF Research Database (Denmark)

    Yuan, Wenping; Liu, Shuguang; Dong, Wenjie

    2014-01-01

    The satellite-derived normalized difference vegetation index (NDVI), which is used for estimating gross primary production (GPP), often includes contributions from both mosses and vascular plants in boreal ecosystems. For the same NDVI, moss can generate only about one-third of the GPP that vascu...

  14. Predicting molybdenum toxicity to higher plants: Estimation of toxicity threshold values

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, S.P., E-mail: steve.mcgrath@bbsrc.ac.u [Soil Science Department, Centre for Soils and Ecosystems Function, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Mico, C.; Zhao, F.J.; Stroud, J.L. [Soil Science Department, Centre for Soils and Ecosystems Function, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Zhang, H.; Fozard, S. [Division of Environmental Science, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2010-10-15

    Four plant species (oilseed rape, Brassica napus L.; red clover, Trifolium pratense L.; ryegrass, Lolium perenne L.; and tomato, Lycopersicon esculentum L.) were tested on ten soils varying widely in soil properties to assess molybdenum (Mo) toxicity. A larger range (66-fold-609-fold) of added Mo concentrations resulting in 50% inhibition of yield (ED{sub 50}) was found among soils than among plant species (2-fold-38-fold), which illustrated that the soils differed widely in the expression of Mo toxicity. Toxicity thresholds based on soil solution Mo narrowed the variation among soils compared to thresholds based on added Mo concentrations. We conclude that plant bioavailability of Mo in soil depends on Mo solubility, but this alone did not decrease the variability in observed toxicity enough to be used in risk assessment and that other soil properties influencing Mo toxicity to plants need to be considered. - Mo toxicity thresholds varied widely in different soils and therefore soil properties need to be taken into account in order to assess the risk of Mo exposure.

  15. Utilization of respiratory energy in higher plants : requirements for 'maintenance' and transport processes

    NARCIS (Netherlands)

    Bouma, T.J.

    1995-01-01

    Quantitative knowledge of both photosynthesis and respiration is required to understand plant growth and resulting crop yield. However, especially the nature of the energy demanding processes that are dependent on dark respiration in full-grown tissues is largely unknown. The main objective

  16. Epigenetic regulation and functional exaptation of transposable elements in higher plants.

    Science.gov (United States)

    Cui, Xiekui; Cao, Xiaofeng

    2014-10-01

    Transposable elements (TEs) are mobile genetic elements that can proliferate in their host genomes. Because of their robust amplification, TEs have long been considered 'selfish DNA', harmful insertions that can threaten host genome integrity. The idea of TEs as junk DNA comes from analysis of epigenetic silencing of their mobility in plants and animals. This idea contrasts with McClintock's characterization of TEs as 'controlling elements'. Emerging studies on the regulatory functions of TEs in plant genomes have updated McClintock's characterization, indicating exaptation of TEs for genetic regulation. In this review, we summarize recent progress in TE silencing, particularly in Arabidopsis and rice, and show that TEs provide an abundant, natural source of regulation for the host genome. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Inherent and environmental patterns in biomass allocation and allometry among higher plants

    Science.gov (United States)

    Poorter, Hendrik

    2017-04-01

    It is well-known that plants may adjust the distribution of biomass over leaves, stems and roots depending on environmental conditions. It is also clear that size is an important factor as well. However, good quantitative insights are lacking. In this talk I analyse biomass allocation patterns to leaves, stems and roots of herbs and woody species. A database was compiled with 11.000 records of leaf, stem and root biomass for 1200 species. First, I'll derive general dose-response curves that describe the relationship between biomass allocation and the 12 most important a-biotic environmental factors and compare them with the changes in leaf, stem and root morphology. Second, I'll focus on allometric relationships between the various organs and test to what extent they comply with models like that for Metabolic Scaling Theory, where the slope of the log-log relationship between leaf and root biomass is expected to have a value of ¾. Third, I analyse how leaf, stem and root mass fractions change as a function of total plant size. This offers a great opportunity to test to what extent there are systematic differences in allocation patterns related to phylogeny (e.g. Gymnosperms vs. Angiosperms, grasses vs. herbaceous dicots) and functional group (e.g. deciduous vs. evergreens). Poorter et al. (2012) Biomass allocation to leaves, stems and roots: meta-analyses of interspecific variation and environmental control. New Phytol. 193: 30-50. Poorter & Sack (2012) Pitfalls and possibilities in the analysis of biomass allocation patterns in plants. Front. Plant Sci. 3: 259. Poorter et al. (2015) How does biomass distribution change with size and differ among species? New Phytol. 208: 736-749

  18. Metabolism of ibuprofen in higher plants: A model Arabidopsis thaliana cell suspension culture system

    Czech Academy of Sciences Publication Activity Database

    Maršík, Petr; Šíša, Miroslav; Lacina, O.; Moťková, Kateřina; Langhansová, Lenka; Rezek, Jan; Vaněk, Tomáš

    2017-01-01

    Roč. 220, JAN (2017), s. 383-392 ISSN 0269-7491 R&D Projects: GA ČR(CZ) GA14-22593S Grant - others:European Regional Development Fund(XE) CZ.2.16/3.1.00/24014 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * Ibuprofen * Metabolism * Plant cells * Sequestration Subject RIV: CE - Biochemistry Impact factor: 5.099, year: 2016

  19. Unravelling the regulatory mechanisms that modulate the MEP pathway in higher plants.

    Science.gov (United States)

    Cordoba, Elizabeth; Salmi, Mari; León, Patricia

    2009-01-01

    The methyl-D-erythritol 4-phosphate pathway is responsible for the biosynthesis of a substantial number of natural compounds of biological and biotechnological importance. In recent years, this pathway has become an obvious target to develop new herbicides and antimicrobial drugs. In addition, the production of a variety of compounds of medical and agricultural interest may be possible through the genetic manipulation of this pathway. To this end, a complete understanding of the molecular mechanisms that regulate this pathway is of tremendous importance. Recent data have accumulated that show some of the multiple mechanisms that regulate the methyl-D-erythritol 4-phosphate pathway in plants. In this review we will describe some of these and discuss their implications. It has been demonstrated that 1-deoxy-D-xylulose-5-phosphate synthase (DXS), the first enzyme of this route, plays a major role in the overall regulation of the pathway. A small gene family codes for this enzyme in most of the plants which have been analysed so far, and the members of these gene families belong to different phylogenetic groups. Each of these genes exhibits a distinct expression pattern, suggesting unique functions. One of the most interesting regulatory mechanisms recently described for this pathway is the post-transcriptional regulation of the level of DXS and DXR proteins. In the case of DXS, this regulation appears conserved among plants, supporting its importance. The evidence accumulated suggests that this regulation might link the activity of this pathway with the plant's physiological conditions and the metabolic demand for the final products of this route.

  20. Proteomics of terpenoid biosynthesis and secretion in trichomes of higher plant species.

    Science.gov (United States)

    Champagne, Antoine; Boutry, Marc

    2016-08-01

    Among the specialized (secondary) plant metabolites, terpenoids represent the most diverse family and are often involved in the defense against pathogens and herbivores. Terpenoids can be produced both constitutively and in response to the environment. At the front line of this defense strategy are the glandular trichomes, which are organs dedicated primarily to the production of specialized metabolites. Mass spectrometry-based proteomics is a powerful tool, which is very useful to investigate enzymes involved in metabolic pathways, such as the synthesis and secretion of terpenoids in glandular trichomes. Here we review the strategies used to investigate the specific roles of these particular organs from non-model plant species, mainly belonging to the Lamiaceae, Solanaceae, and Cannabaceae families. We discuss how proteomics helps to accurately pinpoint candidate proteins to be functionally characterized, and how technological progresses create opportunities for studying low-abundance proteins, such as the ones related to the synthesis and transport of specialized metabolites. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. UV-A radiation effects on higher plants: Exploring the known unknown.

    Science.gov (United States)

    Verdaguer, Dolors; Jansen, Marcel A K; Llorens, Laura; Morales, Luis O; Neugart, Susanne

    2017-02-01

    Ultraviolet-A radiation (UV-A: 315-400nm) is a component of solar radiation that exerts a wide range of physiological responses in plants. Currently, field attenuation experiments are the most reliable source of information on the effects of UV-A. Common plant responses to UV-A include both inhibitory and stimulatory effects on biomass accumulation and morphology. UV-A effects on biomass accumulation can differ from those on root: shoot ratio, and distinct responses are described for different leaf tissues. Inhibitory and enhancing effects of UV-A on photosynthesis are also analysed, as well as activation of photoprotective responses, including UV-absorbing pigments. UV-A-induced leaf flavonoids are highly compound-specific and species-dependent. Many of the effects on growth and development exerted by UV-A are distinct to those triggered by UV-B and vary considerably in terms of the direction the response takes. Such differences may reflect diverse UV-perception mechanisms with multiple photoreceptors operating in the UV-A range and/or variations in the experimental approaches used. This review highlights a role that various photoreceptors (UVR8, phototropins, phytochromes and cryptochromes) may play in plant responses to UV-A when dose, wavelength and other conditions are taken into account. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  2. Effects of long-term radiation exposure on the higher aquatic plants in the Chernobyl exclusion zone

    Energy Technology Data Exchange (ETDEWEB)

    Shevtsova, N.; Gudkov, D. [Institute of Hydrobiology (Russian Federation)

    2014-07-01

    germinated seeds) and pinnacle deviations was registered in plants from the most radioactive contaminated water bodies. Also the decreasing of parasitic stability of one of aquatic plant communities' dominant species - the common reed is observed. The data of the mite Steneotarsonemus phragmitidis and the parasitic fungus Claviceps purpurea hitting of the common reed, correlated with radiation dose rate. It was determined the positive correlation between absorbed dose rate and chromosome aberration rate in roots of the twelve aquatic plants' species from sampling water bodies. The highest rate of chromosome aberrations (up to 17 %) were registered in plants with high level of morphological deviations in seeds germs, but not panicles. The data obtained from the complex analysis of natural aquatic plant communities from the radioactive contaminated water bodies testify about rather high level of genetic efficiency of low doses of long-term exposure. For higher aquatic plants from ChEZ there is observed a realization of radiobiological reactions on morphological and reproductive levels on the background of genetic instability induced by low doses. Document available in abstract form only. (authors)

  3. Integration of a Higher Plant Chamber into the European Space Agency's MELiSSA Pilot Plant: The Canadian Role in Advanced Life Support Test-Bed Development

    Science.gov (United States)

    Waters, Geoffrey; Lawson, Jamie; Gidzinski, Danuta; Stasiak, Michael; Dixon, Mike; Peiro, Enrique; Godia, Francesc; Paille, Christel; Fossen, Arnaud; Lamaze, Brigitte; Lasseur, Christophe

    The European Space Agency's Micro-Ecological Life Support System Alternative (MELiSSA) project has been conceived as a tool for developing the technology of future biological life support systems required for long-term human space exploration missions to the Moon or Mars. The main life support functions of MELiSSA are the recycling of waste (inedible plant biomass, human excrement), carbon dioxide and minerals and the production of food, fresh water and air revitalization. Based on the principle of an aquatic ecosystem, MELiSSA is comprised of four microbial compartments and a higher plant compartment integrated in a closed loop. Each compartment is studied, designed and demonstrated at laboratory scale before being scaled-up for subsequent integration into the MELISSA Pilot Plant (MPP) at the Universitat Aut`noma de Barcelona. Work related to higher plant cultivation systems, o which have been historically focussed at the University of Guelph's Controlled Environment Systems Research Facility (CESRF), has included design of the HPC for the MPP, the metabolic characterization of MELiSSA candidate crops and the validation of theoretical gas exchange and nutrient dynamic models, The presented paper will review some of the recent data and HPC design work of CESRF conducted as part of Canada's involvement in the MELiSSA program and its partnership in the development of the MPP terrestrial demonstration test-bed.

  4. Localization of small heat shock proteins to the higher plant endomembrane system.

    OpenAIRE

    Helm, K W; LaFayette, P R; Nagao, R T; Key, J L; Vierling, E

    1993-01-01

    Three related gene families of low-molecular-weight (LMW) heat shock proteins (HSPs) have been characterized in plants. We describe a fourth LMW HSP family, represented by PsHSP22.7 from Pisum sativum and GmHSP22.0 from Glycine max, and demonstrate that this family of proteins is endomembrane localized. PsHSP22.7 and GmHSP22.0 are 76.7% identical at the amino acid level. Both proteins have amino-terminal signal peptides and carboxyl-terminal sequences characteristic of endoplasmic reticulum (...

  5. Characteristics of fatty acid composition of lipids in higher plant vacuolar membranes.

    Science.gov (United States)

    Makarenko, S P; Konenkina, T A; Salyaev, R K

    2000-01-01

    The fatty acid composition of vacuolar membrane lipids from plant storage tissues and their genesis have been studied. A high content of unsaturated fatty acids (up to 77%) was observed in lipids of these membranes. Linoleic acid prevailed in vacuolar lipids of carrot and red beet (54.2 and 44.2%, respectively). Linolenic acid prevailed in vacuolar lipids of garden radish and turnip (39.7 and 33.9%, respectively). Regarding saturated fatty acids, vacuolar lipids of garden radish, carrot, and red beet contained predominantly palmitic acid (up to 20-24%). Unsaturated fatty acids, petroselinic (C18: 1omega12), cis-vaccenic (C18: 1omega7), hexatrien-7,-10,-13-oic (C16:3omega3) and others, were observed in vacuolar lipids of roots. These acids are usually synthesized in chloroplasts, and their presence in vacuolar lipids can be associated either with the transport of metabolites to the vacuole, or with endocytosis during vacuolar formation in the plant cell. The specific features of fatty acid composition of tonoplast lipids apparently are closely related to the tonoplast unique fluidity and mobility required for running osmotic processes in the cell and for forming transport protein assemblies.

  6. Size, Shape, and Arrangement of Cellulose Microfibril in Higher Plant Cell Walls

    Energy Technology Data Exchange (ETDEWEB)

    Ding, S. Y.

    2013-01-01

    Plant cell walls from maize (Zea mays L.) are imaged using atomic force microscopy (AFM) at the sub-nanometer resolution. We found that the size and shape of fundamental cellulose elementary fibril (CEF) is essentially identical in different cell wall types, i.e., primary wall (PW), parenchyma secondary wall (pSW), and sclerenchyma secondary wall (sSW), which is consistent with previously proposed 36-chain model (Ding et al., 2006, J. Agric. Food Chem.). The arrangement of individual CEFs in these wall types exhibits two orientations. In PW, CEFs are horizontally associated through their hydrophilic faces, and the planar faces are exposed, forming ribbon-like macrofibrils. In pSW and sSW, CEFs are vertically oriented, forming layers, in which hemicelluloses are interacted with the hydrophobic faces of the CEF and serve as spacers between CEFs. Lignification occurs between CEF-hemicelluloses layers in secondary walls. Furthermore, we demonstrated quantitative analysis of plant cell wall accessibility to and digestibility by different cellulase systems at real-time using chemical imaging (e.g., stimulated Raman scattering) and fluorescence microscopy of labeled cellulases (Ding et al., 2012, Science, in press).

  7. Identification of a dispersed MboI repeat family in five higher plant genomes.

    Science.gov (United States)

    Ranade, S A; Lagu, M D; Patankar, S M; Dabak, M M; Dhar, M S; Gupta, V S; Ranjekar, P K

    1988-10-01

    Digestion of nuclear DNAs of five plants, namely Cucurbita maxima (red gourd), Trichosanthes anguina (snake gourd), Cucumis sativus (cucumber), Cajanus cajan (pigeon pea) and Phaseolus vulgaris (french bean) with the restriction endonuclease MboI yielded discrete size classes with molecular weights in the range of 0.5 to 5 kbp. The MboI digestion pattern of Cot 0.1 DNA in french bean is comparable with that of total DNA, indicating that these bands represented highly repeated DNA sequences. Cleavage of the DNAs with varying amounts of MboI indicated the dispersed nature of the repeat families. Southern hybridization studies using french bean highly repetitive DNA as a probe indicated more homology with repeats of pigeon pea and less homology with red gourd, snake gourd and cucumber repeats.

  8. Root uptake of uranium by a higher plant model (Phaseolus vulgaris) bioavailability from soil solution

    Energy Technology Data Exchange (ETDEWEB)

    Laroche, L.; Henner, P.; Camilleri, V.; Garnier-Laplace, J. [CEA Cadarache (DEI/SECRE/LRE), Laboratory of Radioecology and Ecotoxicology, Institute for Radioprotection and Nuclear Safety, 13 - Saint-Paul-lez-Durance (France)

    2004-07-01

    Uranium behaviour in soils is controlled by actions and interactions between physicochemical and biological processes that also determine its bioavailability. In soil solution, uranium(+VI) aqueous speciation undergoes tremendous changes mainly depending on pH, carbonates, phosphates and organic matter. In a first approach to identify bioavailable species of U to plants, cultures were performed using hydroponics, to allow an easy control of the composition of the exposure media. The latter, here an artificial soil solution, was designed to control the uranium species in solution. The geochemical speciation code JCHESS using a database compiled from the OECD/NEA thermochemical database project and verified was used to perform the solution speciation calculations. On this theoretical basis, three domains were defined for short-duration well-defined laboratory experiments in simplified conditions: pH 4.9, 5.8 and 7 where predicted dominant species are uranyl ions, hydroxyl complexes and carbonates respectively. For these domains, biokinetics and characterization of transmembrane transport according to a classical Michaelis Menten approach were investigated. The Free Ion Model (or its derived Biotic Ligand Model) was tested to determine if U uptake is governed by the free uranyl species or if other metal complexes can be assimilated. The effect of different variables on root assimilation efficiency and phyto-toxicity was explored: presence of ligands such as phosphates or carbonates and competitive ions such as Ca{sup 2+} at the 3 pH. According to previous experiments, uranium was principally located in roots whatever the pH and no difference in uranium uptake was evidenced between the main growth stages of the plant. Within the 3 studied chemical domains, results from short-term kinetics evidenced a linear correlation between total uranium concentration in bean roots and that in exposure media, suggesting that total uranium in soil solution could be a good predictor

  9. Regulation of sucrose metabolism in higher plants: localization and regulation of activity of key enzymes

    Science.gov (United States)

    Winter, H.; Huber, S. C.; Brown, C. S. (Principal Investigator)

    2000-01-01

    Sucrose (Suc) plays a central role in plant growth and development. It is a major end product of photosynthesis and functions as a primary transport sugar and in some cases as a direct or indirect regulator of gene expression. Research during the last 2 decades has identified the pathways involved and which enzymes contribute to the control of flux. Availability of metabolites for Suc synthesis and 'demand' for products of sucrose degradation are important factors, but this review specifically focuses on the biosynthetic enzyme sucrose-phosphate synthase (SPS), and the degradative enzymes, sucrose synthase (SuSy), and the invertases. Recent progress has included the cloning of genes encoding these enzymes and the elucidation of posttranslational regulatory mechanisms. Protein phosphorylation is emerging as an important mechanism controlling SPS activity in response to various environmental and endogenous signals. In terms of Suc degradation, invertase-catalyzed hydrolysis generally has been associated with cell expansion, whereas SuSy-catalyzed metabolism has been linked with biosynthetic processes (e.g., cell wall or storage products). Recent results indicate that SuSy may be localized in multiple cellular compartments: (1) as a soluble enzyme in the cytosol (as traditionally assumed); (2) associated with the plasma membrane; and (3) associated with the actin cytoskeleton. Phosphorylation of SuSy has been shown to occur and may be one of the factors controlling localization of the enzyme. The purpose of this review is to summarize some of the recent developments relating to regulation of activity and localization of key enzymes involved in sucrose metabolism in plants.

  10. Transcriptional Regulation of Aluminum-Tolerance Genes in Higher Plants: Clarifying the Underlying Molecular Mechanisms

    Directory of Open Access Journals (Sweden)

    Abhijit A. Daspute

    2017-08-01

    Full Text Available Aluminum (Al rhizotoxicity is one of the major environmental stresses that decrease global food production. Clarifying the molecular mechanisms underlying Al tolerance may contribute to the breeding of Al-tolerant crops. Recent studies identified various Al-tolerance genes. The expression of these genes is inducible by Al. Studies of the major Arabidopsis thaliana Al-tolerance gene, ARABIDOPSIS THALIANA ALUMINUM-ACTIVATED MALATE TRANSPORTER 1 (AtALMT1, which encodes an Al-activated malate transporter, revealed that the Al-inducible expression is regulated by a SENSITIVE TO PROTON RHIXOTOXICITY 1 (STOP1 zinc-finger transcription factor. This system, which involves STOP1 and organic acid transporters, is conserved in diverse plant species. The expression of AtALMT1 is also upregulated by several phytohormones and hydrogen peroxide, suggesting there is crosstalk among the signals involved in the transcriptional regulation of AtALMT1. Additionally, phytohormones and reactive oxygen species (ROS activate various transcriptional responses, including the expression of genes related to increased Al tolerance or the suppression of root growth under Al stress conditions. For example, Al suppressed root growth due to abnormal accumulation of auxin and cytokinin. It activates transcription of TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS 1 and other phytohormone responsive genes in distal transition zone, which causes suppression of root elongation. On the other hand, overexpression of Al inducible genes for ROS-detoxifying enzymes such as GLUTATHIONE–S-TRANSFERASE, PEROXIDASE, SUPEROXIDE DISMUTASE enhances Al resistance in several plant species. We herein summarize the complex transcriptional regulation of an Al-inducible genes affected by STOP1, phytohormones, and ROS.

  11. Tolerance of chufa (Cyperus esculentus L.) plants, representing the higher plant compartment in bioregenerative life support systems, to super-optimal air temperatures

    Science.gov (United States)

    Shklavtsova, E. S.; Ushakova, S. A.; Shikhov, V. N.; Anishchenko, O. V.

    2013-01-01

    Plants intended to be included in the photosynthesizing compartment of the bioregenerative life support system (BLSS) need to be studied in terms of both their production parameters under optimal conditions and their tolerance to stress factors that might be caused by emergency situations. The purpose of this study was to investigate tolerance of chufa (Cyperus esculentus L.) plants to the super-optimal air temperature of 45 ± 1 °C as dependent upon PAR (photosynthetically active radiation) intensity and the duration of the exposure to the stress factor. Chufa plants were grown hydroponically, on expanded clay, under artificial light. The nutrient solution was Knop's mineral medium. Until the plants were 30 days old, they had been grown at 690 μmol m-2 s-1 PAR and air temperature 25 °C. Thirty-day-old plants were exposed to the temperature 45 °C for 6 h, 20 h, and 44 h at PAR intensities 690 μmol m-2 s-1 and 1150 μmol m-2 s-1. The exposure to the damaging air temperature for 44 h at 690 μmol m-2 s-1 PAR caused irreversible damage to PSA, resulting in leaf mortality. In chufa plants exposed to heat shock treatment at 690 μmol m-2 s-1 PAR for 6 h and 20 h, respiration exceeded photosynthesis, and CO2 release in the light was recorded. Functional activity of photosynthetic apparatus, estimated from parameters of pulse-modulated chlorophyll fluorescence in Photosystem 2 (PS 2), decreased 40% to 50%. After the exposure to the stress factor was finished, functional activity of PSA recovered its initial values, and apparent photosynthesis (Papparent) rate after a 20-h exposure to the stress factor was 2.6 times lower than before the elevation of the temperature. During the first hours of plant exposure to the temperature 45 °C at 1150 μmol m-2 s-1 PAR, respiration rate was higher than photosynthesis rate, but after 3-4 h of the exposure, photosynthetic processes exceeded oxidative ones and CO2 absorption in the light was recorded. At the end of the 6-h exposure

  12. The Cyclization Mechanism of Cyclodextrin Glycosyltransferase (CGTase) as Revealed by a γ-Cyclodextrin-CGTase Complex at 1.8-Å Resolution

    NARCIS (Netherlands)

    Uitdehaag, Joost C.M.; Kalk, Kor H.; Veen, Bart A. van der; Dijkhuizen, Lubbert; Dijkstra, Bauke W.

    1999-01-01

    The enzyme cyclodextrin glycosyltransferase is closely related to α-amylases but has the unique ability to produce cyclodextrins (circular α(1→4)-linked glucoses) from starch. To characterize this specificity we determined a 1.8-Å structure of an E257Q/D229N mutant cyclodextrin glycosyltransferase

  13. Higher β-diversity observed for herbs over woody plants is driven by stronger habitat filtering in a tropical understory.

    Science.gov (United States)

    Murphy, Stephen J; Salpeter, Kara; Comita, Liza S

    2016-08-01

    Herbaceous plants are a key component of tropical forests. Previous work indicates that herbs contribute substantially to the species richness of tropical plant communities. However, the processes structuring tropical herb diversity, and how they contrast with woody communities, have been underexplored. Within the understory of a 50-ha forest dynamics plot in central Panama, we compared the diversity, distribution, and abundance of vascular herbaceous plants with woody seedlings (i.e., tree and lianas woody seedlings, indicating higher spatial variation in this stratum. We observed no correlation between local richness or compositional uniqueness of herbs and woody seedlings across sites, indicating that different processes control the spatial patterns of woody and herbaceous diversity and composition. Habitat associations were strongest for herbs, as indicated by greater compositional dissimilarity among habitat types. Likewise, environmental variables explained a larger proportion of the variation in species richness and composition for herbs than for woody seedlings (richness = 25%, 14%, 12%; composition = 25%, 9%, 6%, for herbs, trees, and lianas, respectively). These differences between strata did not appear to be due to differences in lifespan alone, based on data from adult trees. Our results point to contrasting assembly mechanisms for herbaceous and woody communities, with herbs showing stronger niche-derived structure. Future research on tropical herbaceous communities is likely to yield new insights into the many processes structuring diverse plant communities. © 2016 by the Ecological Society of America.

  14. Association mapping for phenology and plant architecture in maize shows higher power for developmental traits compared with growth influenced traits.

    Science.gov (United States)

    Bouchet, S; Bertin, P; Presterl, T; Jamin, P; Coubriche, D; Gouesnard, B; Laborde, J; Charcosset, A

    2017-03-01

    Plant architecture, phenology and yield components of cultivated plants have repeatedly been shaped by selection to meet human needs and adaptation to different environments. Here we assessed the genetic architecture of 24 correlated maize traits that interact during plant cycle. Overall, 336 lines were phenotyped in a network of 9 trials and genotyped with 50K single-nucleotide polymorphisms. Phenology was the main factor of differentiation between genetic groups. Then yield components distinguished dents from lower yielding genetic groups. However, most of trait variation occurred within group and we observed similar overall and within group correlations, suggesting a major effect of pleiotropy and/or linkage. We found 34 quantitative trait loci (QTLs) for individual traits and six for trait combinations corresponding to PCA coordinates. Among them, only five were pleiotropic. We found a cluster of QTLs in a 5 Mb region around Tb1 associated with tiller number, ear row number and the first PCA axis, the latter being positively correlated to flowering time and negatively correlated to yield. Kn1 and ZmNIP1 were candidate genes for tillering, ZCN8 for leaf number and Rubisco Activase 1 for kernel weight. Experimental repeatabilities, numbers of QTLs and proportion of explained variation were higher for traits related to plant development such as tillering, leaf number and flowering time, than for traits affected by growth such as yield components. This suggests a simpler genetic determinism with larger individual QTL effects for the first category.

  15. Red mud a byproduct of aluminum production contains soluble vanadium that causes genotoxic and cytotoxic effects in higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Mišík, Miroslav [Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, Vienna (Austria); Burke, Ian T. [Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Reismüller, Matthias; Pichler, Clemens; Rainer, Bernhard [Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, Vienna (Austria); Mišíková, Katarina [Department of Botany, Faculty of Natural Sciences, Comenius University, Bratislava (Slovakia); Mayes, William M. [Centre for Environmental and Marine Sciences, University of Hull, Scarborough YO11 3AZ (United Kingdom); Knasmueller, Siegfried, E-mail: siegfried.knasmueller@meduniwien.ac.at [Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, Vienna (Austria)

    2014-09-15

    Red mud (RM) is a byproduct of aluminum production; worldwide between 70 and 120 million tons is produced annually. We analyzed RM which was released in the course of the Kolontar disaster in Hungary into the environment in acute and genotoxicity experiments with plants which are widely used for environmental monitoring. We detected induction of micronuclei which reflect chromosomal damage in tetrads of Tradescantia and in root cells of Allium as well as retardation of root growth with contaminated soils and leachates. Chemical analyses showed that RM contains metals, in particular high concentrations of vanadium. Follow-up experiments indicated that vanadate causes the effects in the plants. This compound causes also in humans DNA damage and positive results were obtained in carcinogenicity studies. Since it was found also in RM from other production sites our findings indicate that its release in the environment is a global problem which should be studied in more detail. Capsule abstract: Our findings indicate that the red mud causes genotoxic effect in plants probably due to the presence of vanadate which is contained at high concentrations in the residue. - Highlights: • Red mud, a by-product of aluminum production, causes DNA-damage in higher plants. • We showed that this effect is caused by vanadate a known carcinogenic genotoxin. • Vanadate is contained in high concentrations in the residue. • Release of red mud may cause adverse effects in ecosystems and affect human health.

  16. Novel Path Towards Colistin Resistance In Pseudomonas Aeruginosa During Chronic Infection Involves Polymorphisms In Uncharacterized Glycosyltransferase Gene

    DEFF Research Database (Denmark)

    Hermansen, Grith Miriam Maigaard; Jelsbak, Lars

    2015-01-01

    Introduction: Antibiotic resistance development in the gram-negative bacterium Pseudomonas aeruginosa is an increasing problem. The effect of colistin, one of the few last resort drugs commonly given to cystic fibrosis (CF) patients, is dependent on the lipopolysaccharide (LPS) structure. We have...... identified a novel gene cluster, which is involved in colistin susceptibility in chronically infecting P. aeruginosa strains. The gene cluster contains two uncharacterized glycosyltransferases and a gene of unknown function. During chronic infection of CF patients one of the glycosyltransferase genes...

  17. Higher plant and vertebrate species richness in Spanish and some mediterranean mountains

    Directory of Open Access Journals (Sweden)

    Martínez-Rica, J. P.

    1998-12-01

    Full Text Available This paper reviews the biodiversity of the Spanish and some other Mediterranean mountains. These have some of the richest areas for vascular plants recorded apart from some areas in the tropics. The number of endemic species is substantial. Six areas in Spain and four other Mediterranean areas are described in detail. A special plea is made for a comprehensive detailed vegetation map for European mountains to include the Spanish and Mediterranean mountains.

    [fr] Ce travail porte sur la biodiversité de quelques montagnes méditerranéennes, notamment celle de l'Espagne. Ces dernières montrent une flore vasculaire des plus riches au monde, si l'on excepte les pays tropicaux. Aussi le nombre d'espèces endémiques est très important. Six systèmes montagneux d'Espagne et quatre autres sur le pourtour méditerranéen sont étudiés en détail. Dans une section spéciale on étudie la carte de végétation synthétique des montagnes européennes, de façon à inclure les montagnes de l'Espagne et de la Méditerranée. [es] Se estudia la biodiversidad de las montañas españolas y de otras mediterráneas. Si se exceptúan algunas áreas tropicales, se trata de una de las áreas más ricas en plantas vasculares. El número de especies endémicas resulta sustancial. Se estudian con mayor detalle seis áreas montañosas de España y cuatro áreas más del Mediterráneo. De un modo particular se estudia un mapa sintético de vegetación de las montañas de Europa en relación con las montañas de España y del Mediterráneo.

  18. A database of PCR primers for the chloroplast genomes of higher plants

    Directory of Open Access Journals (Sweden)

    Heinze Berthold

    2007-02-01

    Full Text Available Abstract Background Chloroplast genomes evolve slowly and many primers for PCR amplification and analysis of chloroplast sequences can be used across a wide array of genera. In some cases 'universal' primers have been designed for the purpose of working across species boundaries. However, the essential information on these primer sequences is scattered throughout the literature. Results A database is presented here which assembles published primer information for chloroplast DNA. Additional primers were designed to fill gaps where little or no primer information could be found. Amplicons are either the genes themselves (typically useful in studies of sequence variation in higher-order phylogeny or they are spacers, introns, and intergenic regions (for studies of phylogeographic patterns within and among species. The current list of 'generic' primers consists of more than 700 sequences. Wherever possible, we give the locations of the primers in the thirteen fully sequenced chloroplast genomes (Nicotiana tabacum, Atropa belladonna, Spinacia oleracea, Arabidopsis thaliana, Populus trichocarpa, Oryza sativa, Pinus thunbergii, Marchantia polymorpha, Zea mays, Oenothera elata, Acorus calamus, Eucalyptus globulus, Medicago trunculata. Conclusion The database described here is designed to serve as a resource for researchers who are venturing into the study of poorly described chloroplast genomes, whether for large- or small-scale DNA sequencing projects, to study molecular variation or to investigate chloroplast evolution.

  19. Amino acids implicated in plant defense are higher in Candidatus Liberibacter asiaticus-tolerant citrus varieties.

    Science.gov (United States)

    Killiny, Nabil; Hijaz, Faraj

    2016-01-01

    Citrus Huanglongbing (HLB), also known as citrus greening, has been threatening the citrus industry since the early 1900's and up to this date there are no effective cures for this disease. Field observations and greenhouse controlled studies demonstrated that some citrus genotypes are more tolerant to Candidatus Liberibacter asiaticus (CLas) pathogen than others. However, the mechanisms underpinning tolerance has not been determined yet. The phloem sap composition of CLas-tolerant and sensitive citrus varieties was studied to identify metabolites that could be responsible for their tolerance to CLas. The citrus phloem sap was collected by centrifugation and was analyzed with gas chromatography-mass spectrometry after methyl chloroformate derivatization. Thirty-three metabolites were detected in the phloem sap of the studied varieties: twenty 20 amino acids, eight 8 organic acids, and five 5 fatty acids. Interestingly, the levels of most amino acids, especially those implicated in plantdefense to pathogens such as phenylalanine, tyrosine, tryptophan, lysine, and asparagine were higher in tolerant varieties. Although the level of organic acids varied between cultivars, this variation was not correlated with citrus resistance to CLas and could be cultivar specific. The fatty acids were found in trace amounts and in most cases their levels were not significantly different among varieties. Better understanding of the mechanisms underpinning citrus tolerance to CLas will help in developing economically tolerant varieties.

  20. Zeaxanthin Radical Cation Formation in Minor Light-Harvesting Complexes of Higher Plant Antenna

    Energy Technology Data Exchange (ETDEWEB)

    Avenson, Thomas H.; Ahn, Tae Kyu; Zigmantas, Donatas; Niyogi, Krishna K.; Li, Zhirong; Ballottari, Matteo; Bassi, Roberto; Fleming, Graham R.

    2008-01-31

    Previous work on intact thylakoid membranes showed that transient formation of a zeaxanthin radical cation was correlated with regulation of photosynthetic light-harvesting via energy-dependent quenching. A molecular mechanism for such quenching was proposed to involve charge transfer within a chlorophyll-zeaxanthin heterodimer. Using near infrared (880-1100 nm) transient absorption spectroscopy, we demonstrate that carotenoid (mainly zeaxanthin) radical cation generation occurs solely in isolated minor light-harvesting complexes that bind zeaxanthin, consistent with the engagement of charge transfer quenching therein. We estimated that less than 0.5percent of the isolated minor complexes undergo charge transfer quenching in vitro, whereas the fraction of minor complexes estimated to be engaged in charge transfer quenching in isolated thylakoids was more than 80 times higher. We conclude that minor complexes which bind zeaxanthin are sites of charge transfer quenching in vivo and that they can assume Non-quenching and Quenching conformations, the equilibrium LHC(N)<--> LHC(Q) of which is modulated by the transthylakoid pH gradient, the PsbS protein, and protein-protein interactions.

  1. Position 228 in Paenibacillus macerans cyclodextrin glycosyltransferase is critical for 2-O-d-glucopyranosyl-l-ascorbic acid synthesis.

    Science.gov (United States)

    Chen, Sheng; Xiong, Yanjun; Su, Lingqia; Wang, Lei; Wu, Jing

    2017-04-10

    The markedly stable l-ascorbic acid (L-AA) derivative 2-O-d-glucopyranosyl-l-ascorbic acid (AA-2G) has been widely used in the fields of food, medicine, cosmetics, and husbandry. Cyclodextrin glycosyltransferase (CGTase) is considered suitable for the large-scale production of AA-2G. In this work, Paenibacillus macerans CGTase was used to produce AA-2G and the production was 13.5g/l. An amino-acid sequence alignment of α-, β-, and α⁄β-CGTase indicated that the Phe at position 228 of P. macerans CGTase was different from the amino acids at this position in other CGTases (Met, Val, or Ile). In addition, the CGTases from Anaerobranca gottschalkii and Bacillus circulans 251, which have Val and Met at position 228, were shown to produce 28.9 and 35.7g/l AA-2G, respectively, which verified the importance of this position for AA-2G synthesis. Subsequently, P. macerans CGTase mutants F228M and F228V were constructed and shown to produce 24.8g/l and 24.0g/l AA-2G, respectively, which are 84% and 78% higher than that of wild-type P. macerans CGTase, respectively. Kinetic analysis of AA-2G synthesis showed that affinities of the two mutants for L-AA and the catalytic efficiencies increased. Meanwhile, the mutants had lower cyclization activity but higher disproportionation activities, which is beneficial for AA-2G synthesis. All these results indicated that amino acid at position 228 of P. macerans CGTase is crucial to AA-2G synthesis. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A greater foraging scale, not a higher foraging precision, may facilitate invasion by exotic plants in nutrient-heterogeneous conditions.

    Science.gov (United States)

    Chen, Bao-Ming; Su, Jin-Quan; Liao, Hui-Xuan; Peng, Shao-Lin

    2017-12-22

    Soil nutrient heterogeneity has been proposed to influence competitive outcomes among different plant species. Thus, it is crucial to understand the effects of environmental heterogeneity on competition between exotic invasive and native species. However, the effects of soil nutrient heterogeneity on the competition between invasive and native plants have rarely been linked to root foraging behaviour. In this study, a competition experiment was performed with two invasive-native species pairs (BP-VC, Bidens pilosa vs. Vernonia cinerea; MM-PS, Mikania micrantha vs. Paederia scandens) grown under homogeneous and heterogeneous conditions in a common greenhouse environment. Root activity was assessed by determining the amount of strontium (Sr) taken up by the shoot of each species. The invasive species exhibited a greater foraging scale, whereas the native species exhibited a higher foraging precision. A trade-off between foraging scale and precision was observed within each pair of invasive-native species. Compared with soil homogeneity, soil heterogeneity significantly increased the biomass of the two invasive species, B. pilosa and M. micrantha, under competitive conditions. Within each pair, the invasive species exhibited greater relative competitive ability with respect to shoot mass, and considerably more Sr taken up by the invasive species compared with the native species. The Sr acquisition results indicate that nutrient-poor conditions may facilitate the competitive ability of the native species V. cinerea, whereas M. micrantha may possess a stronger competitive ability regardless of soil nutrient conditions. Soil nutrient heterogeneity has the potential to promote the invasion of these two exotic species due to their larger foraging scale, stronger competitive ability and greater root activity relative to their counterpart native species. The present work highlights the importance of soil heterogeneity in plant invasion, particularly with regards to root

  3. Organic Acids: The Pools of Fixed Carbon Involved in Redox Regulation and Energy Balance in Higher Plants

    Directory of Open Access Journals (Sweden)

    Abir U Igamberdiev

    2016-07-01

    Full Text Available Organic acids are synthesized in plants as a result of the incomplete oxidation of photosynthetic products and represent the stored pools of fixed carbon accumulated due to different transient times of conversion of carbon compounds in metabolic pathways. When redox level in the cell increases, e.g., in conditions of active photosynthesis, the tricarboxylic acid (TCA cycle in mitochondria is transformed to a partial cycle supplying citrate for the synthesis of 2-oxoglutarate and glutamate (citrate valve, while malate is accumulated and participates in the redox balance in different cell compartments (via malate valve. This results in malate and citrate frequently being the most accumulated acids in plants. However, the intensity of reactions linked to the conversion of these compounds can cause preferential accumulation of other organic acids, e.g., fumarate or isocitrate, in higher concentrations than malate and citrate. The secondary reactions, associated with the central metabolic pathways, in particularly with the TCA cycle, result in accumulation of other organic acids that are derived from the intermediates of the cycle. They form the additional pools of fixed carbon and stabilize the TCA cycle. Trans-aconitate is formed from citrate or cis-aconitate, accumulation of hydroxycitrate can be linked to metabolism of 2-oxoglutarate, while 4-hydroxy-2-oxoglutarate can be formed from pyruvate and glyoxylate. Glyoxylate, a product of either glycolate oxidase or isocitrate lyase, can be converted to oxalate. Malonate is accumulated at high concentrations in legume plants. Organic acids play a role in plants in providing redox equilibrium, supporting ionic gradients on membranes, and acidification of the extracellular medium.

  4. Engineering of cyclodextrin product specificity and pH optima of the thermostable cyclodextrin glycosyltransferase from Thermoanaerobacterium thermosulfurigenes EM1

    NARCIS (Netherlands)

    Wind, Richèle D.; Uitdehaag, Joost C.M.; Buitelaar, Reinetta M.; Dijkstra, Bauke W.; Dijkhuizen, Lubbert

    1998-01-01

    The product specificity and pH optimum of the thermostable cyclodextrin glycosyltransferase (CGTase) from Thermoanaerobacterium thermosulfurigenes EM1 was engineered using a combination of x-ray crystallography and site-directed mutagenesis. Previously, a crystal soaking experiment with the Bacillus

  5. The Arabidopsis Family GT43 Glycosyltransferases Form Two Functionally Nonredundant Groups Essential for the Elongation of Glucuronoxylan Backbone

    Science.gov (United States)

    There exist four members of family GT43 glycosyltransferases in the Arabidopsis (Arabidopsis thaliana) genome, and mutations of two of them, IRX9 and IRX14, have previously been shown to cause a defect in glucuronoxylan (GX) biosynthesis. However, it is currently unknown whether ...

  6. Enzymatic circularization of a malto-octaose linear chain studied by stochastic reaction path calculations on cyclodextrin glycosyltransferase

    NARCIS (Netherlands)

    Uitdehaag, Joost C.M.; Veen, Bart A. van der; Dijkhuizen, Lubbert; Elber, Ron; Dijkstra, Bauke W.

    2001-01-01

    Cyclodextrin glycosyltransferase (CGTase) is an enzyme belonging to the ol-amylase family that forms cyclodextrins (circularly linked oligosaccharides) from starch. X-ray work has indicated that this cyclization reaction of CGTase involves a 23-Angstrom movement of the nonreducing end of a linear

  7. Tomato UDP-Glucose Sterol Glycosyltransferases: A Family of Developmental and Stress Regulated Genes that Encode Cytosolic and Membrane-Associated Forms of the Enzyme

    Directory of Open Access Journals (Sweden)

    Karla Ramirez-Estrada

    2017-06-01

    Full Text Available Sterol glycosyltransferases (SGTs catalyze the glycosylation of the free hydroxyl group at C-3 position of sterols to produce sterol glycosides. Glycosylated sterols and free sterols are primarily located in cell membranes where in combination with other membrane-bound lipids play a key role in modulating their properties and functioning. In contrast to most plant species, those of the genus Solanum contain very high levels of glycosylated sterols, which in the case of tomato may account for more than 85% of the total sterol content. In this study, we report the identification and functional characterization of the four members of the tomato (Solanum lycopersicum cv. Micro-Tom SGT gene family. Expression of recombinant SlSGT proteins in E. coli cells and N. benthamiana leaves demonstrated the ability of the four enzymes to glycosylate different sterol species including cholesterol, brassicasterol, campesterol, stigmasterol, and β-sitosterol, which is consistent with the occurrence in their primary structure of the putative steroid-binding domain found in steroid UDP-glucuronosyltransferases and the UDP-sugar binding domain characteristic for a superfamily of nucleoside diphosphosugar glycosyltransferases. Subcellular localization studies based on fluorescence recovery after photobleaching and cell fractionation analyses revealed that the four tomato SGTs, like the Arabidopsis SGTs UGT80A2 and UGT80B1, localize into the cytosol and the PM, although there are clear differences in their relative distribution between these two cell fractions. The SlSGT genes have specialized but still largely overlapping expression patterns in different organs of tomato plants and throughout the different stages of fruit development and ripening. Moreover, they are differentially regulated in response to biotic and abiotic stress conditions. SlSGT4 expression increases markedly in response to osmotic, salt, and cold stress, as well as upon treatment with abscisic

  8. Integral use of amaranth starch to obtain cyclodextrin glycosyltransferase, by Bacillus megaterium, to produce β-cyclodextrin.

    Directory of Open Access Journals (Sweden)

    María Belem Arce-Vázquez

    2016-09-01

    Full Text Available Cyclodextrin glycosyltransferase (CGTase is an enzyme that produces cyclodextrins (CDs from starch and related carbohydrates, producing a mixture of α-, β-, and γ-CDs in different amounts. CGTase production, mainly by Bacillus sp., depends on fermentation conditions such as pH, temperature, concentration of nutrients, carbon and nitrogen sources, among others. Bacillus megaterium CGTase produces those three types of CDs, however, β-CD should prevail. Although waxy corn starch (CS is used industrially to obtain CGTase and CDs because of its high amylopectin content, alternative sources such as amaranth starch (AS could be used to accomplish those purposes. AS has high susceptibility to the amylolytic activity of CGTase because of its 80% amylopectin content. Therefore, the aim of this work was evaluate the AS as carbon source for CGTase production by B. megaterium in a submerged fermentation. Afterwards, the CGTase was purified partially and its activity to synthesize α-, β- and γ-CDs was evaluated using 1% AS as substrate. B. megaterium produced a 66 kDa CGTase (Topt=50°C; pHopt=8.0, from the early exponential growth phase which lasted 36 h. The maximum CGTase specific activity (106.62±8.33 U/mg protein was obtained after 36 h of culture. CGTase obtained with a Km=0.152 mM and a Vmax=13.4 µM/min yielded 40.47% total CDs using AS which was roughly twice as much as that of corn starch (CS; 24.48%. High costs to produce CDs in the pharmaceutical and food industries might be reduced by using AS because of its higher α-, β- and γ-CDs production (12.81%, 17.94% and 9.92%, respectively in a shorter time than that needed for CS.

  9. Volatile metabolites of higher plants cenoses as photosynthesizing LSS component under optimum conditions and temperature stress at different light intensities

    Science.gov (United States)

    Gitelson, J.; Tikhomirov, A.; Parshina, O.; Ushakova, S.; Kalacheva, G.

    One of major yet still poorly known functions of the photosynthesizing component in life support system (LSS) is to improve the quality of air through volatile emissions (VE) of plants capable of accumulating in closed volumes, interacting between themselves and having favorable or adverse impact on humans. In all likelihood, the effect of stress changing the functional condition of plants is to be accompanied with alteration in composition and quantity of VE. There are practically no works dealing with effect of such environmental factors as light intensity and elevated air temperature on qualitative and quantitative composition of VE by higher plants' cenoses. Meanwhile experimental modeling and investigation of stability of man-made human life support systems make this problem of very important. The aim of this work is to experimentally evaluate relationship between qualitative and quantitative composition of VE and the functional condition of wheat cenoses as the basic culture of LSS photosynthesizing component under normal conditions and under temperature stress against light of different intensity. Effect of elevated temperature 35 and 45°C (with the light intensity of 70, 150 or 240 W/m2 PAR) on photosynthesis, respiration, qualitative and quantitative composition of VE of wheat (Triticum aestuvi L., variety 232) cenoses was studied in the atmosphere of growth chambers. More than 20 volatile compounds (terpenoids - a pinene, +3 carene, limonene, benzene, a - and trans-caryophylene, a - and ?-terpinene, their derivatives, aromatic hydrocarbons, etc.) were qualitatively and quantitatively estimated by chromatomassspectroscopy (GC-MS). The light intensity of 240 W/m2 PAR at 35° increase, and at 45° - decrease of thermal stability of photosynthesis and respiration. Elevated temperatures resulted in non- uniform variation of the rate and direction of VE synthesis. VE was highest at irradiance 70 W/m 2 and lowest at 240 W/m2 and 35° . During the reparation

  10. Higher photosynthesis, nutrient- and energy-use efficiencies contribute to invasiveness of exotic plants in a nutrient poor habitat in northeast China.

    Science.gov (United States)

    Liu, Ming-Chao; Kong, De-Liang; Lu, Xiu-Rong; Huang, Kai; Wang, Shuo; Wang, Wei-Bin; Qu, Bo; Feng, Yu-Long

    2017-08-01

    The roles of photosynthesis-related traits in invasiveness of introduced plant species are still not well elucidated, especially in nutrient-poor habitats. In addition, little effort has been made to determine the physiological causes and consequences of the difference in these traits between invasive and native plants. To address these problems, we compared the differences in 16 leaf functional traits related to light-saturated photosynthetic rate (P max ) between 22 invasive and native plants in a nutrient-poor habitat in northeast China. The invasive plants had significantly higher P max , photosynthetic nitrogen- (PNUE), phosphorus- (PPUE), potassium- (PKUE) and energy-use efficiencies (PEUE) than the co-occurring natives, while leaf nutrient concentrations, construction cost (CC) and specific leaf area were not significantly different between the invasive and native plants. The higher PNUE contributed to higher P max for the invasive plants, which in turn contributed to higher PPUE, PKUE and PEUE. CC changed independently with other traits such as P max , PNUE, PPUE, PKUE and PEUE, showing two trait dimensions, which may facilitate acclimation to multifarious niche dimensions. Our results indicate that the invasive plants have a superior resource-use strategy, i.e. higher photosynthesis under similar resource investments, contributing to invasion success in the barren habitat. © 2017 Scandinavian Plant Physiology Society.

  11. Granal stacking of thylakoid membranes in higher plant chloroplasts: the physicochemical forces at work and the functional consequences that ensue.

    Science.gov (United States)

    Chow, Wah Soon; Kim, Eun-Ha; Horton, Peter; Anderson, Jan M

    2005-12-01

    The formation of grana in chloroplasts of higher plants is examined in terms of the subtle interplay of physicochemical forces of attraction and repulsion. The attractive forces between two adjacent membranes comprise (1) van der Waals attraction that depends on the abundance and type of atoms in each membrane, on the distance between the membranes and on the dielectric constant, (2) depletion attraction that generates local order by granal stacking at the expense of greater disorder (i.e. entropy) in the stroma, and (3) an electrostatic attraction of opposite charges located on adjacent membranes. The repulsive forces comprise (1) electrostatic repulsion due to the net negative charge on the outer surface of thylakoid membranes, (2) hydration repulsion that operates at small separations between thylakoid membranes due to layers of bound water molecules, and (3) steric hindrance due to bulky protrusions of Photosystem I (PSI) and ATP synthase into the stroma. In addition, specific interactions may occur, but they await experimental demonstration. Although grana are not essential for photosynthesis, they are ubiquitous in higher plants. Grana may have been selected during evolution for the functional advantages that they confer on higher plants. The functional consequences of grana stacking include (1) enhancement of light capture through a vastly increased area-to-volume ratio and connectivity of several PSIIs with large functional antenna size, (2) the ability to control the lateral separation of PSI from PSII and, therefore, the balanced distribution of excitation energy between two photosystems working in series, (3) the reversible fine-tuning of energy distribution between the photosystems by State 1-State 2 transitions, (4) the ability to regulate light-harvesting via controlled thermal dissipation of excess excitation energy, detected as non-photochemical quenching, (5) dynamic flexibility in the light reactions mediated by a granal structure in response to

  12. A Neogene Higher Plant N-Alkane Carbon and Hydrogen Isotope Record From the Gulf of Mexico

    Science.gov (United States)

    Tipple, B. J.; Pagani, M.

    2006-12-01

    Water availability and a plant's capacity to cope with water stress are expressed in carbon and hydrogen isotopic compositions of leaf waxes. Therefore, coupled sedimentary n-alkane δ13C and δD isotope records provide unique continental-scale information about the paleo-hydrological cycle and its influence on biology over long time scales. In this study, we assess the relationship between Neogene North American climate and floral change, particularly C4 grass expansion, by establishing δ13C and δD records of higher-plant leaf wax n-alkanes from Gulf of Mexico sediments (DSDP site 94). Changes in the hydrogen isotope composition of leaf water can be driven by changes in evaporation/evapotranspiration or changes in the evaporative source from which precipitation derives. However, for this study changes in moisture source are unlikely because these sediments located in Gulf of Mexico likely received the majority of precipitation from the Gulf of Mexico itself over the time interval studied. In general, δ13C and δD values shift in concert, with the most positive δ13C and δD values occurring near the Epoch boundaries. N-alkane δ13C values reflect factors other than water stress alone, including the isotopic composition of atmospheric CO2, plant community, and atmospheric pCO2. Notably, 13C enrichment occurring near the Oligocene/Miocene boundary potentially reflects the rapid decrease in pCO2 at this time. In addition, between 4.5 and 5.5 Ma, n-alkane δ13C values trend more negative as δD becomes increasingly D-enriched, indicative of increased evaporation. Given that contemporaneous North American terrestrial isotope (Passey et al., 2002) and equatorial Atlantic marine (Wagner, 2002) records show similar trends, it appears that major changes in the hydrological cycle took place at this time.

  13. Over-expression of AtPAP2 in Camelina sativa leads to faster plant growth and higher seed yield.

    Science.gov (United States)

    Zhang, Youjun; Yu, Laura; Yung, Ka-Fu; Leung, Dennis Yc; Sun, Feng; Lim, Boon L

    2012-04-02

    Lipids extracted from seeds of Camelina sativa have been successfully used as a reliable source of aviation biofuels. This biofuel is environmentally friendly because the drought resistance, frost tolerance and low fertilizer requirement of Camelina sativa allow it to grow on marginal lands. Improving the species growth and seed yield by genetic engineering is therefore a target for the biofuels industry. In Arabidopsis, overexpression of purple acid phosphatase 2 encoded by Arabidopsis (AtPAP2) promotes plant growth by modulating carbon metabolism. Overexpression lines bolt earlier and produce 50% more seeds per plant than wild type. In this study, we explored the effects of overexpressing AtPAP2 in Camelina sativa. Under controlled environmental conditions, overexpression of AtPAP2 in Camelina sativa resulted in longer hypocotyls, earlier flowering, faster growth rate, higher photosynthetic rate and stomatal conductance, increased seed yield and seed size in comparison with the wild-type line and null-lines. Similar to transgenic Arabidopsis, activity of sucrose phosphate synthase in leaves of transgenic Camelina was also significantly up-regulated. Sucrose produced in photosynthetic tissues supplies the building blocks for cellulose, starch and lipids for growth and fuel for anabolic metabolism. Changes in carbon flow and sink/source activities in transgenic lines may affect floral, architectural, and reproductive traits of plants. Lipids extracted from the seeds of Camelina sativa have been used as a major constituent of aviation biofuels. The improved growth rate and seed yield of transgenic Camelina under controlled environmental conditions have the potential to boost oil yield on an area basis in field conditions and thus make Camelina-based biofuels more environmentally friendly and economically attractive.

  14. Over-expression of AtPAP2 in Camelina sativa leads to faster plant growth and higher seed yield

    Directory of Open Access Journals (Sweden)

    Zhang Youjun

    2012-04-01

    Full Text Available Abstract Background Lipids extracted from seeds of Camelina sativa have been successfully used as a reliable source of aviation biofuels. This biofuel is environmentally friendly because the drought resistance, frost tolerance and low fertilizer requirement of Camelina sativa allow it to grow on marginal lands. Improving the species growth and seed yield by genetic engineering is therefore a target for the biofuels industry. In Arabidopsis, overexpression of purple acid phosphatase 2 encoded by Arabidopsis (AtPAP2 promotes plant growth by modulating carbon metabolism. Overexpression lines bolt earlier and produce 50% more seeds per plant than wild type. In this study, we explored the effects of overexpressing AtPAP2 in Camelina sativa. Results Under controlled environmental conditions, overexpression of AtPAP2 in Camelina sativa resulted in longer hypocotyls, earlier flowering, faster growth rate, higher photosynthetic rate and stomatal conductance, increased seed yield and seed size in comparison with the wild-type line and null-lines. Similar to transgenic Arabidopsis, activity of sucrose phosphate synthase in leaves of transgenic Camelina was also significantly up-regulated. Sucrose produced in photosynthetic tissues supplies the building blocks for cellulose, starch and lipids for growth and fuel for anabolic metabolism. Changes in carbon flow and sink/source activities in transgenic lines may affect floral, architectural, and reproductive traits of plants. Conclusions Lipids extracted from the seeds of Camelina sativa have been used as a major constituent of aviation biofuels. The improved growth rate and seed yield of transgenic Camelina under controlled environmental conditions have the potential to boost oil yield on an area basis in field conditions and thus make Camelina-based biofuels more environmentally friendly and economically attractive.

  15. Genotoxicity Assessment of Volatile Organic Compounds in Landfill Gas Emission Using Comet Assay in Higher Terrestrial Plant.

    Science.gov (United States)

    Na Roi-Et, Veerapas; Chiemchaisri, Wilai; Chiemchaisri, Chart

    2017-02-01

    Genotoxicity model is developed to assess the individual subacute toxicity of benzene, toluene, ethylbenzene, and xylene (BTEX) at very low levels as in a landfill gas. Golden Pothos (Epipremnum aureum), a higher plant, was tested under variation of benzene 54-5656 ng/L, toluene 10-4362 ng/L, ethylbenzene 28-4997 ng/L, xylene 53-4845 ng/L, for 96 h. DNA fragmentation in plant leaves were investigated via comet assay. The results show that DNA migration ratio increased with the BTEX concentrations, but at different rates. The 50% effective concentration (EC50) of DNA fragmentation from the dose-response relationships indicated toluene has the highest EC50 value and followed by benzene, xylene and ethylbenzene. Alternatively, ethylbenzene has the highest toxicity unit and followed by xylene, benzene and toluene as described by toxicity unit (TU). In conclusion, comet assay of Pothos can be used in differentiating DNA fragmentation against very low levels of BTEX in the atmosphere. Pothos is recommended for genotoxicity assessment of a low BTEX contaminated atmosphere.

  16. Glycemic Response to Corn Starch Modified with Cyclodextrin Glycosyltransferase and its Relationship to Physical Properties.

    Science.gov (United States)

    Dura, A; Yokoyama, W; Rosell, C M

    2016-09-01

    Corn starch was modified with cyclodextrin glycosyltransferase (CGTase) below the gelatinization temperature. The porous granules with or without CGTase hydrolysis products may be used as an alternative to modified corn starches in foods applications. The amount and type of hydrolysis products were determined, containing mainly β-cyclodextrin (CD), which will influence pasting behavior and glycemic response in mice. Irregular surface and small holes were observed by microscopic analysis and differences in pasting properties were observed in the presence of hydrolysis products. Postprandial blood glucose in mice fed gelatinized enzymatically modified starch peaked earlier than their ungelatinized counterparts. However, in ungelatinized enzymatically modified starches, the presence of β- CD may inhibit the orientation of amylases slowing hydrolysis, which may help to maintain lower blood glucose levels. Significant correlations were found between glycemic curves and viscosity pattern of starches.

  17. Tandem action of glycosyltransferases in the maturation of vancomycin and teicoplanin aglycones: novel glycopeptides.

    Science.gov (United States)

    Losey, H C; Peczuh, M W; Chen, Z; Eggert, U S; Dong, S D; Pelczer, I; Kahne, D; Walsh, C T

    2001-04-17

    The glycopeptides vancomycin and teicoplanin are clinically important antibiotics. The carbohydrate portions of these molecules affect biological activity, and there is great interest in developing efficient strategies to make carbohydrate derivatives. To this end, genes encoding four glycosyltransferases, GtfB, C, D, E, were subcloned from Amycolatopsis orientalis strains that produce chloroeremomycin (GtfB, C) or vancomycin (GtfD, E) into Escherichia coli. After expression and purification, each glycosyltransferase (Gtf) was characterized for activity either with the aglycones (GtfB, E) or the glucosylated derivatives (GtfC, D) of vancomycin and teicoplanin. GtfB efficiently glucosylates vancomycin aglycone using UDP-glucose as the glycosyl donor to form desvancosaminyl-vancomycin (vancomycin pseudoaglycone), with k(cat) of 17 min(-1), but has very low glucosylation activity, GtfC and GtfD, synthesis of UDP-beta-L-4-epi-vancosamine was undertaken. This NDP-sugar served as a substrate for both GtfC and GtfD in the presence of vancomycin pseudoaglycone (GtfC and GtfD) or the glucosylated teicoplanin scaffold, 7 (GtfD). The GtfC product was the 4-epi-vancosaminyl form of vancomycin. Remarkably, GtfD was able to utilize both an unnatural acceptor, 7, and an unnatural nucleotide sugar donor, UDP-4-epi-vancosamine, to synthesize a novel hybrid teicoplanin/vancomycin glycopeptide. These results establish the enzymatic activity of these four Gtfs, begin to probe substrate specificity, and illustrate how they can be utilized to make variant sugar forms of both the vancomycin and the teicoplanin class of glycopeptide antibiotics.

  18. Cyclodextrin Formation by the Thermostable α-Amylase of Thermoanaerobacterium thermosulfurigenes EM1 and Reclassification of the Enzyme as a Cyclodextrin Glycosyltransferase

    NARCIS (Netherlands)

    Wind, Richèle D.; Liebl, Wolfgang; Buitelaar, Reinetta M.; Penninga, Dirk; Spreinat, Andreas; Dijkhuizen, Lubbert; Bahl, Hubert

    1995-01-01

    Extensive characterization of the thermostable α-amylase of Clostridium thermosulfurogenes EM1, recently reclassified as Thermoanaerobacterium thermosulfurigenes, clearly demonstrated that the enzyme is a cyclodextrin glycosyltransferase (CGTase). Product analysis after incubation of the enzyme with

  19. CYCLODEXTRIN FORMATION BY THE THERMOSTABLE ALPHA-AMYLASE OF THERMOANAEROBACTERIUM THERMOSULFURIGENES EM1 AND RECLASSIFICATION OF THE ENZYME AS A CYCLODEXTRIN GLYCOSYLTRANSFERASE

    NARCIS (Netherlands)

    WIND, RD; LIEBL, W; BUITELAAR, RM; PENNINGA, D; SPREINAT, A; DIJKHUIZEN, L; BAHL, H

    Extensive characterization of the thermostable alpha-amylase of Clostridium thermosulfurogenes EM1, recently reclassified as Thermoanaerobacterium thermosulfurigenes, clearly demonstrated that the enzyme is a cyclodextrin glycosyltransferase (CGTase). Product analysis after incubation of the enzyme

  20. Slow molecular evolution in 18S rDNA, rbcL and nad5 genes of mosses compared with higher plants.

    Science.gov (United States)

    Stenøien, H K

    2008-03-01

    The evolutionary potential of bryophytes (mosses, liverworts and hornworts) has been debated for decades. Fossil record and biogeographical distribution patterns suggest very slow morphological evolution and the retainment of several ancient traits since the split with vascular plants some 450 million years ago. Many have argued that bryophytes may evolve as rapidly as higher plants on the molecular level, but this hypothesis has not been tested so far. Here, it is shown that mosses have experienced significantly lower rates of molecular evolution than higher plants within 18S rDNA (nuclear), rbcL (chloroplast) and nad5 (mitochondrial) genes. Mosses are on an average evolving 2-3 times slower than ferns, gymnosperms and angiosperms; and also green algae seem to be evolving faster than nonvascular plants. These results support the observation of a general correlation between morphological and molecular evolutionary rates in plants and also show that mosses are 'evolutionary sphinxes' regarding both morphological and molecular evolutionary potential.

  1. Interactions of metal-based engineered nanoparticles with aquatic higher plants: A review of state of current knowledge

    CSIR Research Space (South Africa)

    Thwala, Melusi

    2016-01-01

    Full Text Available . Dissolution appears to be a key mechanism driving bioaccumulation of ENPs, whereas nanoparticulates often adsorb to plant surfaces with minimal internalisation. However, few reports document the internalisation of ENPs by plants, thus the role...

  2. Results of the first stage (2002-2009) of investigation of higher plants onboard RS ISS, as an element of future closed Life Support Systems

    Science.gov (United States)

    Sychev, Vladimir; Levinskikh, Margarita; Podolsky, Igor; Bingham, Gail; Novikova, Nataliya; Sugimoto, Manabu

    A key task for biomedical human support in long-term manned space expeditions is the develop-ment of the Life Support System (LSS). It is expected that in the first continuous interplanetary expeditions LSS of only a few biological elements of the LSS, such as higher plants will be in-cluded. Therefore, investigations of growth and development of higher plants for consideration in the LSS are of high importance. In a period from October, 2002 to December 2009, 15 ex-periments on cultivation of different plants, including two genetically marked species of dwarf peas, a leaf vegetable strain of Mizuna, radish, barley and wheat were conducted in space greenhouse "LADA" onboard Russian Segment (RS) of International Space Station (ISS). The experiments resulted in the conclusion that the properties of growth and development of plants grown in space greenhouse "LADA" were unaffected by spaceflight conditions. In experiments conducted in a period from 2003 to 2005, it was shown for the first time that pea plants pre-serve reproductive functions, forming viable seeds during at least four continuous full cycles of ontogenesis ("seed to seed") under spaceflight conditions. No changes were found in the genetic apparatus of the pea plants in the four "space" generations. Since 2005, there have been routine collections of microbiological samples from the surfaces of the plants grown on-board in "LADA" greenhouse. Analysis has shown that the properties of contamination of the plants grown aboard by microorganism contain no abnormal patterns. Since 2008, the plants cultivated in "LADA" greenhouse have been frozen onboard RS ISS in the MELFI refrigerator and transferred to the Earth for further investigations. Investigations of Mizuna plants grown and frozen onboard of ISS, showed no differences between "ground control" and "space" plants in chemical and biochemical properties. There also no stress-response was found in kashinriki strain barley planted and frozen onboard ISS.

  3. Evidence for a universal pathway of abscisic acid biosynthesis in higher plants from sup 18 O incorporation patterns

    Energy Technology Data Exchange (ETDEWEB)

    Zeevaart, J.A.D.; Heath, T.G.; Gage, D.A. (Michigan State University, East Lansing (USA))

    1989-12-01

    Previous labeling studies of abscisic acid (ABA) with {sup 18}O{sub 2} have been mainly conducted with water-stressed leaves. In this study, {sup 18}O incorporation into ABA of stressed leaves of various species was compared with {sup 18}O labeling of ABA of turgid leaves and of fruit tissue in different stages of ripening. In stressed leaves of all six species investigated, avocado (Persea americana), barley (Hordeum vulgare), bean (Phaseolus vulgaris), cocklebur (Xanthium strumarium), spinach (Spinacia oleracea), and tobacco (Nicotiana tabacum), {sup 18}O was most abundant in the carboxyl group, whereas incorporation of a second and third {sup 18}O in the oxygen atoms on the ring of ABA was much less prominent after 24 h in {sup 18}O{sub 2}. ABA from turgid bean leaves showed significant {sup 18}O incorporation, again with highest {sup 18}O enrichment in the carboxyl group. On the basis of {sup 18}O-labeling patterns observed in ABA from different tissues it is concluded that, despite variations in precusor pool sizes and intermediate turnover rates, there is a universal pathway of ABA biosynthesis in higher plants which involves cleavage of a larger precursor molecule, presumably an oxygenated carotenoid.

  4. A non-enzymatic function of Golgi glycosyltransferases: mediation of Golgi fragmentation by interaction with non-muscle myosin IIA.

    Science.gov (United States)

    Petrosyan, Armen; Cheng, Pi-Wan

    2013-06-01

    The Golgi apparatus undergoes morphological changes under stress or malignant transformation, but the precise mechanisms are not known. We recently showed that non-muscle myosin IIA (NMIIA) binds to the cytoplasmic tail of Core 2 N-acetylglucosaminyltransferase mucus-type (C2GnT-M) and transports it to the endoplasmic reticulum for recycling. Here, we report that Golgi fragmentation induced by brefeldin A (BFA) or coatomer protein (β-COP) knockdown (KD) in Panc1-bC2GnT-M (c-Myc) cells is accompanied by the increased association of NMIIA with C2GnT-M and its degradation by proteasomes. Golgi fragmentation is prevented by inhibition or KD of NMIIA. Using multiple approaches, we have shown that the speed of BFA-induced Golgi fragmentation is positively correlated with the levels of this enzyme in the Golgi. The observation is reproduced in LNCaP cells which express high levels of two endogenous glycosyltransferases--C2GnT-L and β-galactoside α2,3 sialyltransferase 1. NMIIA is found to form complexes with these two enzymes but not Golgi matrix proteins. The KD of both enzymes or the prevention of Golgi glycosyltransferases from exiting endoplasmic reticulum reduced Golgi-associated NMIIA and decreased the BFA-induced fragmentation. Interestingly, the fragmented Golgi detected in colon cancer HT-29 cells can be restored to a compact morphology after inhibition or KD of NMIIA. The Golgi disorganization induced by the microtubule or actin destructive agent is NMIIA-independent and does not affect the levels of glycosyltransferases. We conclude that NMIIA interacts with Golgi residential but not matrix proteins, and this interaction is responsible for Golgi fragmentation induced by β-COP KD or BFA treatment. This is a novel non-enzymatic function of Golgi glycosyltransferases.

  5. Structural and Functional Analysis of a New Subfamily of Glycosyltransferases Required for Glycosylation of Serine-rich Streptococcal Adhesins

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Fan; Erlandsen, Heidi; Ding, Lei; Li, Jingzhi; Huang, Ying; Zhou, Meixian; Liang, Xiaobo; Ma, Jinbiao; Wu, Hui (UAB)

    2011-09-16

    Serine-rich repeat glycoproteins (SRRPs) are a growing family of bacterial adhesins found in many streptococci and staphylococci; they play important roles in bacterial biofilm formation and pathogenesis. Glycosylation of this family of adhesins is essential for their biogenesis. A glucosyltransferase (Gtf3) catalyzes the second step of glycosylation of a SRRP (Fap1) from an oral streptococcus, Streptococcus parasanguinis. Although Gtf3 homologs are highly conserved in SRRP-containing streptococci, they share minimal homology with functionally known glycosyltransferases. We report here the 2.3 {angstrom} crystal structure of Gtf3. The structural analysis indicates that Gtf3 forms a tetramer and shares significant structural homology with glycosyltransferases from GT4, GT5, and GT20 subfamilies. Combining crystal structural analysis with site-directed mutagenesis and in vitro glycosyltransferase assays, we identified residues that are required for UDP- or UDP-glucose binding and for oligomerization of Gtf3 and determined their contribution to the enzymatic activity of Gtf3. Further in vivo studies revealed that the critical amino acid residues identified by the structural analysis are crucial for Fap1 glycosylation in S. parasanguinis in vivo. Moreover, Gtf3 homologs from other streptococci were able to rescue the gtf3 knock-out mutant of S. parasanguinis in vivo and catalyze the sugar transfer to the modified SRRP substrate in vitro, demonstrating the importance and conservation of the Gtf3 homologs in glycosylation of SRRPs. As the Gtf3 homologs only exist in SRRP-containing streptococci, we conclude that the Gtf3 homologs represent a unique subfamily of glycosyltransferases.

  6. Integral Use of Amaranth Starch to Obtain Cyclodextrin Glycosyltransferase, by Bacillus megaterium, to Produce β-Cyclodextrin

    OpenAIRE

    María Belem Arce-Vázquez; Edith Ponce-Alquicira; Ezequiel Delgado-Fornué; Ruth Pedroza-Islas; Gerardo Díaz-Godínez; JORGE SORIANO-SANTOS

    2016-01-01

    Cyclodextrin glycosyltransferase (CGTase) is an enzyme that produces cyclodextrins (CDs) from starch and related carbohydrates, producing a mixture of ?-, ?-, and ?-CDs in different amounts. CGTase production, mainly by Bacillus sp., depends on fermentation conditions such as pH, temperature, concentration of nutrients, carbon and nitrogen sources, among others. Bacillus megaterium CGTase produces those three types of CDs, however, ?-CD should prevail. Although, waxy corn starch (CS) is used ...

  7. [A feasibility study on the highly-efficient electronic fluorescent lamp used as a lighting source for cultivation of higher plant in space].

    Science.gov (United States)

    Guo, S S; Xu, B

    1999-08-01

    To testify that the Highly-efficient Electronic Fluorescent Lamp (HEFL) can be used as a sole lighting source for the cultivation of higher plants in space. The HEFL was utilized as the lighting source for the culture of three varieties of Luctuca sativa L in the lately-constructed Space Higher Plant Cultivation Ground-based Experimental Facility(SHPCGEF). Other culturing conditions were: temperature 20 +/- 0.2 degrees C, relative humidity (75 +/- 1)%, average photosynthetic active radiation (PAR) 70 micromol m-2 s-1 PPF, average wind velocity 0.45 m/s, photoperiod 24 h light/0 h dark, peat + vermiculite substrate culture, useful growing area 1.2 m2, growing period 28 d, one variety was cultured at every batch. Following plant maturing and being harvested, observations of external morphology of above-ground parts of the plants, measurements and calculations of edible biomass output and photosynthetic efficiency, analysis of nutrient compositions such as proteins, fats, carbohydrates, amino acids, vitamins and elemental compositions of lettuce leaves, and comparisons with formerly-related experiments were made. All of the above-mentioned targets met our demands, some of them were superior to the results of other similar experiments. The HEFL can completely meet the needs for the growth and development of some higher plants planned to be grown in space, its physical characters basically accord with the demands, so it can be utilized as the only lighting source for higher plant growth in space environmental conditions.

  8. Overexpression of a glycosyltransferase gene SrUGT74G1 from Stevia improved growth and yield of transgenic Arabidopsis by catechin accumulation.

    Science.gov (United States)

    Guleria, Praveen; Yadav, Sudesh Kumar

    2014-03-01

    Steviol glycoside and gibberellin biosynthetic routes are known as divergent branches of a common origin in Stevia. A UDP-glycosyltransferase encoded by SrUGT74G1 catalyses the conversion of steviolbioside into stevioside in Stevia rebaudiana leaves. In the present study, transgenic Arabidopsis thaliana overexpressing SrUGT74G1 cDNA from Stevia were developed to check the probability of stevioside biosynthesis in them. However, stevioside accumulation was not evident in transgenics. Also, the transgenic Arabidopsis showed no change in GA3 content on SrUGT74G1 overexpression. Surprisingly, significant accumulation of catechin was noticed in transgenics. The transgenics showed a considerable increase in shoot length, root length and rosette area. An increase in free radical scavenging activity of transgenics was noticed. Moreover, the seed yield of transgenics was also increased by 6-15% than control. Additionally, variation in trichome branching pattern on leaf surface of transgenics was observed. The trichome branching pattern was also validated by exogenous catechin exposure (10, 50, 100 ng ml(-1)) to control plants. Hence, present study reports the probable role of SrUGT74G1 from Stevia in catechin accumulation of transgenic Arabidopsis thaliana. Thus, detailed study in present perspective has revealed the role of Stevia SrUGT74G1 gene in trichome branching pattern, improved vegetative growth, scavenging potential and seed yield by catechin accumulation in transgenic Arabidopsis.

  9. Plant glyco-biotechnology on the way to synthetic biology

    Directory of Open Access Journals (Sweden)

    Andreas eLoos

    2014-10-01

    Full Text Available Plants are increasingly being used for the production of recombinant proteins. One reason is that plants are highly amenable for glycan engineering processes and allow the production of therapeutic proteins with increased efficacies due to optimized glycosylation profiles. Removal and insertion of glycosylation reactions by knock-out/knock-down approaches and introduction of glycosylation enzymes have paved the way for the humanization of the plant glycosylation pathway. The insertion of heterologous enzymes at exactly the right stage of the existing glycosylation pathway has turned out to be of utmost importance for optimal results. To enable such precise targeting chimeric enzymes have been constructed. In this short review we will exemplify the importance of correct targeting of glycosyltransferases, we will give an overview of the targeting mechanism of glycosyltransferases, describe chimeric enzymes used in plant N-glycosylation engineering and illustrate how plant glycoengineering builds on the tools offered by synthetic biology to construct such chimeric enzymes.

  10. PHOSPHORYLATION/DEPHOSPHORYLATION OF MITOCHONDRIAL PROTEINS IN REDOX-SIGNALLING OF HIGHER PLANTS UNDER ABIOTIC STRESS CONDITIONS

    Directory of Open Access Journals (Sweden)

    Subota I.Yu.

    2012-08-01

    Full Text Available We studied an impact of the widely spread intra-cellular signals Ca2+ and сAMP on activity of the protein phosphorylation in maize mitochondria. The use of the isolated mitochondria is a convenient model system for investigation of the different physiological processes, for example for simulation of the different stress conditions. The treatment of maize mitochondria with high concentration of calcium ions which mimics the initial stage of apoptosis led to an increase of the phosphorylation level of some proteins and to an additional phosphorylation of the 59 and 66 kDa proteins. The treatment of the mitoplasts, i.e., the mitochondria devoid of the outer membrane with calcium ions insignificantly induced the activity of protein phosphorylation. It is assumed that the outer membrane is essential for Ca2+ signal transduction to plant mitochondria. We also identified a 94 kDa protein involved in phosphorylation of the mitochondrial proteins. This protein might be a single-subunit protein kinase or one of the subunits of the protein kinase complex. Antimycin A and KCN which are the inhibitors of mitochondria respiration increased the phosphorylation activity of the mitochondrial polypeptides. The effect of this inhibitors was similar both in in organello system and at the level of the whole plant. It should be noticed that at the level of the whole plant the effect of KCN on activity of the mitochondrial protein phosphorylation was more essential. Some considerable differences were found both at the level of protein phosphorylation and in electrophoresis patterns representing the intact mitochondria, the mitoplasts and the outer membrane fraction. The activity of protein phosphorylation in mitoplasts and the outer membrane fraction was extremely high compared to the phosphorylation activity of the mitochondrial proteins. This could be explained by the higher level of “substrate phosphoprotein phosphatase” in the outer membrane of mitochondria

  11. Identification and characterization of glycosyltransferases involved in the synthesis of the side chains of the cell wall pectic polysaccharide rhamnogalacturonan II

    Energy Technology Data Exchange (ETDEWEB)

    O' Neill, Malcolm [Univ. of Georgia, Athens, GA (United States)

    2015-08-31

    Our goal was to gain insight into the genes and proteins involved in the biosynthesis of rhamnogalacturonan II (RG-II), a borate cross-linked and structurally conserved pectic polysaccharide present in the primary cell walls of all vascular plants. The research conducted during the funding period established that (i) Avascular plants have the ability to synthesize UDP-apiose but lack the glycosyltransferase machinery required to synthesize RG-II or other apiose-containing cell wall glycans. (ii) RG-II structure is highly conserved in the Lemnaceae (duckweeds and relatives). However, the structures of other wall pectins and hemicellulose have changed substantial during the diversification of the Lemnaceae. This supports the notion that a precise structure of RG-II must be maintained to allow borate cross-linking to occur in a controlled manner. (iii) Enzymes involved in the conversion of UDP-GlcA to UDP-Api, UDP-Xyl, and UDP-Ara may have an important role in controlling the composition of duckweed cell walls. (iv) RG-II exists as the borate ester cross-linked dimer in the cell walls of soybean root hairs and roots. Thus, RG-II is present in the walls of plants cells that grow by tip or by expansive growth. (v) A reduction in RG-II cross-linking in the maize tls1 mutant, which lacks a borate channel protein, suggests that the growth defects observed in the mutant are, at least in part, due to defects in the cell wall.

  12. Transport and compartmentation of phosphite in higher plant cells - kinetic and 31P nuclear magnetic resonance studies

    NARCIS (Netherlands)

    Danova-Alt, R.; Dijkema, C.; Waard, de P.; Köck, M.

    2008-01-01

    Phosphite (Phi, H(2)PO(3)(-)), being the active part of several fungicides, has been shown to influence not only the fungal metabolism but also the development of phosphate-deficient plants. However, the mechanism of phosphite effects on plants is still widely unknown. In this paper we analysed

  13. The Glycosyltransferases of LPS Core: A Review of Four Heptosyltransferase Enzymes in Context

    Directory of Open Access Journals (Sweden)

    Joy M. Cote

    2017-10-01

    Full Text Available Bacterial antibiotic resistance is a rapidly expanding problem in the world today. Functionalization of the outer membrane of Gram-negative bacteria provides protection from extracellular antimicrobials, and serves as an innate resistance mechanism. Lipopolysaccharides (LPS are a major cell-surface component of Gram-negative bacteria that contribute to protecting the bacterium from extracellular threats. LPS is biosynthesized by the sequential addition of sugar moieties by a number of glycosyltransferases (GTs. Heptosyltransferases catalyze the addition of multiple heptose sugars to form the core region of LPS; there are at most four heptosyltransferases found in all Gram-negative bacteria. The most studied of the four is HepI. Cells deficient in HepI display a truncated LPS on their cell surface, causing them to be more susceptible to hydrophobic antibiotics. HepI–IV are all structurally similar members of the GT-B structural family, a class of enzymes that have been found to be highly dynamic. Understanding conformational changes of heptosyltransferases are important to efficiently inhibiting them, but also contributing to the understanding of all GT-B enzymes. Finding new and smarter methods to inhibit bacterial growth is crucial, and the Heptosyltransferases may provide an important model for how to inhibit many GT-B enzymes.

  14. Production and characterization of cyclodextrin glycosyltransferase from Bacillus sp. isolated from Cuban

    Directory of Open Access Journals (Sweden)

    Kárel Hernández Sánchez

    2014-12-01

    Full Text Available A cyclodextrin glycosyltransferase (CGTase from an alkaliphilic Bacillus sp. strain, isolated from Cuban soil, was purified with Sephadex G-50 with a yield of 66.5%. The CGTase was stable over a very wide pH range, 6.0–10, at 25°C and was most active at pH 7.5. The enzyme exhibited an optimum temperature of 60°C and was stable to 50°C for at least 8 h. The T50 value – defined as the temperature at which 50% of the initial activity was retained–was 63°C in this enzyme. The influence of substrate or product concentration on the initial rate of CD production was studied, and the kinetic parameters were determined. The analysis of kinetic parameters Km and Vmax was obtained by the action of CGTase on the starch of corn with respect to β-CD, and the values were 4.1 g/L and 5.2 μM β-CD/min ml, respectively. The purified CGTase from Bacillus sp. could be used for an efficient cyclodextrin (CD production which is the significant yield of γ- CDs.

  15. Crystal Structure of a UDP-glucose-specific Glycosyltransferase from a Mycobacterium Species

    Energy Technology Data Exchange (ETDEWEB)

    Fulton, Zara; McAlister, Adrian; Wilce, Matthew C.J.; Brammananth, Rajini; Zaker-Tabrizi, Leyla; Perugini, Matthew A.; Bottomley, Stephen P.; Coppel, Ross L.; Crellin, Paul K.; Rossjohn, Jamie; Beddoe, Travis (Monash); (Melbourne)

    2008-10-24

    Glycosyltransferases (GTs) are a large and ubiquitous family of enzymes that specifically transfer sugar moieties to a range of substrates. Mycobacterium tuberculosis contains a large number of GTs, many of which are implicated in cell wall synthesis, yet the majority of these GTs remain poorly characterized. Here, we report the high resolution crystal structures of an essential GT (MAP2569c) from Mycobacterium avium subsp. paratuberculosis (a close homologue of Rv1208 from M. tuberculosis) in its apo- and ligand-bound forms. The structure adopted the GT-A fold and possessed the characteristic DXD motif that coordinated an Mn{sup 2+} ion. Atypical of most GTs characterized to date, MAP2569c exhibited specificity toward the donor substrate, UDP-glucose. The structure of this ligated complex revealed an induced fit binding mechanism and provided a basis for this unique specificity. Collectively, the structural features suggested that MAP2569c may adopt a 'retaining' enzymatic mechanism, which has implications for the classification of other GTs in this large superfamily.

  16. Glycosyltransferases and Transpeptidases/Penicillin-Binding Proteins: Valuable Targets for New Antibacterials

    Directory of Open Access Journals (Sweden)

    Eric Sauvage

    2016-02-01

    Full Text Available Peptidoglycan (PG is an essential macromolecular sacculus surrounding most bacteria. It is assembled by the glycosyltransferase (GT and transpeptidase (TP activities of multimodular penicillin-binding proteins (PBPs within multiprotein complex machineries. Both activities are essential for the synthesis of a functional stress-bearing PG shell. Although good progress has been made in terms of the functional and structural understanding of GT, finding a clinically useful antibiotic against them has been challenging until now. In contrast, the TP/PBP module has been successfully targeted by β-lactam derivatives, but the extensive use of these antibiotics has selected resistant bacterial strains that employ a wide variety of mechanisms to escape the lethal action of these antibiotics. In addition to traditional β-lactams, other classes of molecules (non-β-lactams that inhibit PBPs are now emerging, opening new perspectives for tackling the resistance problem while taking advantage of these valuable targets, for which a wealth of structural and functional knowledge has been accumulated. The overall evidence shows that PBPs are part of multiprotein machineries whose activities are modulated by cofactors. Perturbation of these systems could lead to lethal effects. Developing screening strategies to take advantage of these mechanisms could lead to new inhibitors of PG assembly. In this paper, we present a general background on the GTs and TPs/PBPs, a survey of recent issues of bacterial resistance and a review of recent works describing new inhibitors of these enzymes.

  17. Peptidoglycan glycosyltransferase substrate mimics as templates for the design of new antibacterial drugs

    Directory of Open Access Journals (Sweden)

    Adeline eDerouaux

    2013-03-01

    Full Text Available Peptidoglycan (PG is an essential net-like macromolecule that surrounds bacteria, gives them their shape, and protects them against their own high osmotic pressure. PG synthesis inhibition leads to bacterial cell lysis, making it an important target for many antibiotics. The final two reactions in PG synthesis are performed by penicillin-binding proteins (PBPs. Their glycosyltransferase (GT activity uses the lipid II precursor to synthesize glycan chains and their transpeptidase (TP activity catalyzes the cross-linking of two glycan chains via the peptide side chains. Inhibition of either of these two reactions leads to bacterial cell death. β-Lactam antibiotics target the transpeptidation reaction while antibiotic therapy based on inhibition of the GTs remains to be developed. Ongoing research is trying to fill this gap by studying the interactions of GTs with inhibitors and substrate mimics and utilizing the latter as templates for the design of new antibiotics. In this mini review we present an updated overview on the GTs and describe the structure-activity relationship of recently developed synthetic ligands.

  18. Understanding water deficit stress-induced changes in the basic metabolism of higher plants - biotechnologically and sustainably improving agriculture and the ecoenvironment in arid regions of the globe.

    Science.gov (United States)

    Shao, Hong-Bo; Chu, Li-Ye; Jaleel, C Abdul; Manivannan, P; Panneerselvam, R; Shao, Ming-An

    2009-01-01

    Water is vital for plant growth, development and productivity. Permanent or temporary water deficit stress limits the growth and distribution of natural and artificial vegetation and the performance of cultivated plants (crops) more than any other environmental factor. Productive and sustainable agriculture necessitates growing plants (crops) in arid and semiarid regions with less input of precious resources such as fresh water. For a better understanding and rapid improvement of soil-water stress tolerance in these regions, especially in the water-wind eroded crossing region, it is very important to link physiological and biochemical studies to molecular work in genetically tractable model plants and important native plants, and further extending them to practical ecological restoration and efficient crop production. Although basic studies and practices aimed at improving soil water stress resistance and plant water use efficiency have been carried out for many years, the mechanisms involved at different scales are still not clear. Further understanding and manipulating soil-plant water relationships and soil-water stress tolerance at the scales of ecology, physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important in exploring anti-drought gene resources in various life forms, but modern agriculturally sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics have further practical prospects. In this review, we discuss physiological and molecular insights and effects in basic plant metabolism, drought tolerance strategies under drought conditions in higher plants for sustainable agriculture and ecoenvironments in arid and semiarid areas of the world. We conclude that biological measures are the bases for the solutions to the issues relating to the different types of

  19. Snf2 family gene distribution in higher plant genomes reveals DRD1 expansion and diversification in the tomato genome.

    Directory of Open Access Journals (Sweden)

    Joachim W Bargsten

    Full Text Available As part of large protein complexes, Snf2 family ATPases are responsible for energy supply during chromatin remodeling, but the precise mechanism of action of many of these proteins is largely unknown. They influence many processes in plants, such as the response to environmental stress. This analysis is the first comprehensive study of Snf2 family ATPases in plants. We here present a comparative analysis of 1159 candidate plant Snf2 genes in 33 complete and annotated plant genomes, including two green algae. The number of Snf2 ATPases shows considerable variation across plant genomes (17-63 genes. The DRD1, Rad5/16 and Snf2 subfamily members occur most often. Detailed analysis of the plant-specific DRD1 subfamily in related plant genomes shows the occurrence of a complex series of evolutionary events. Notably tomato carries unexpected gene expansions of DRD1 gene members. Most of these genes are expressed in tomato, although at low levels and with distinct tissue or organ specificity. In contrast, the Snf2 subfamily genes tend to be expressed constitutively in tomato. The results underpin and extend the Snf2 subfamily classification, which could help to determine the various functional roles of Snf2 ATPases and to target environmental stress tolerance and yield in future breeding.

  20. Incorporation of T4 phage DNA into a specific DNA fraction from the higher plant Matthiola incana.

    Science.gov (United States)

    Gradmann-Rebel, W; Hemleben, V

    1976-01-01

    Isolated T4 phage DNA (sigma=1.694 g/ml) is applied to seedlings of the crucifer Matthiola incana (DNA density sigma=1.698 g/ml). The phage DNA can partly be reextracted from the plants in a specific DNA fraction, which is predominantly characterized by its unusual high density (high density complex=HDC; sigma=1.724 g/ml). DNA:DNA hybridization studies show that phage specific DNA sequences are preserved in the HDC. Results of BrdUrd labeling of the plant DNA before and during incubation with T4DNA suggest that the HDC is composed of T4DNA and a plant DNA component of high density. The analysis of ultrasonicated HDC confirms this suggestion. The ability of plant cells to recognize and handle T4 DNA specifically is discussed.

  1. The maize INDETERMINATE1 flowering time regulator defines a highly conserved zinc finger protein family in higher plants

    Directory of Open Access Journals (Sweden)

    Colasanti Joseph

    2006-06-01

    Full Text Available Abstract Background The maize INDETERMINATE1 gene, ID1, is a key regulator of the transition to flowering and the founding member of a transcription factor gene family that encodes a protein with a distinct arrangement of zinc finger motifs. The zinc fingers and surrounding sequence make up the signature ID domain (IDD, which appears to be found in all higher plant genomes. The presence of zinc finger domains and previous biochemical studies showing that ID1 binds to DNA suggests that members of this gene family are involved in transcriptional regulation. Results Comparison of IDD genes identified in Arabidopsis and rice genomes, and all IDD genes discovered in maize EST and genomic databases, suggest that ID1 is a unique member of this gene family. High levels of sequence similarity amongst all IDD genes from maize, rice and Arabidopsis suggest that they are derived from a common ancestor. Several unique features of ID1 suggest that it is a divergent member of the maize IDD family. Although no clear ID1 ortholog was identified in the Arabidopsis genome, highly similar genes that encode proteins with identity extending beyond the ID domain were isolated from rice and sorghum. Phylogenetic comparisons show that these putative orthologs, along with maize ID1, form a group separate from other IDD genes. In contrast to ID1 mRNA, which is detected exclusively in immature leaves, several maize IDD genes showed a broad range of expression in various tissues. Further, Western analysis with an antibody that cross-reacts with ID1 protein and potential orthologs from rice and sorghum shows that all three proteins are detected in immature leaves only. Conclusion Comparative genomic analysis shows that the IDD zinc finger family is highly conserved among both monocots and dicots. The leaf-specific ID1 expression pattern distinguishes it from other maize IDD genes examined. A similar leaf-specific localization pattern was observed for the putative ID1 protein

  2. Proteomic characterization and three-dimensional electron microscopy study of PSII-LHCII supercomplexes from higher plants.

    Science.gov (United States)

    Pagliano, Cristina; Nield, Jon; Marsano, Francesco; Pape, Tillmann; Barera, Simone; Saracco, Guido; Barber, James

    2014-09-01

    In higher plants a variable number of peripheral LHCII trimers can strongly (S), moderately (M) or loosely (L) associate with the dimeric PSII core (C2) complex via monomeric Lhcb proteins to form PSII-LHCII supercomplexes with different structural organizations. By solubilizing isolated stacked pea thylakoid membranes either with the α or β isomeric forms of the detergent n-dodecyl-D-maltoside, followed by sucrose density ultracentrifugation, we previously showed that PSII-LHCII supercomplexes of types C2S2M2 and C2S2, respectively, can be isolated [S. Barera et al., Phil. Trans. R Soc. B 67 (2012) 3389-3399]. Here we analysed their protein composition by applying extensive bottom-up and top-down mass spectrometry on the two forms of the isolated supercomplexes. In this way, we revealed the presence of the antenna proteins Lhcb3 and Lhcb6 and of the extrinsic polypeptides PsbP, PsbQ and PsbR exclusively in the C2S2M2 supercomplex. Other proteins of the PSII core complex, common to the C2S2M2 and C2S2 supercomplexes, including the low molecular mass subunits, were also detected and characterized. To complement the proteomic study with structural information, we performed negative stain transmission electron microscopy and single particle analysis on the PSII-LHCII supercomplexes isolated from pea thylakoid membranes solubilized with n-dodecyl-α-D-maltoside. We observed the C2S2M2 supercomplex in its intact form as the largest PSII complex in our preparations. Its dataset was further analysed in silico, together with that of the second largest identified sub-population, corresponding to its C2S2 subcomplex. In this way, we calculated 3D electron density maps for the C2S2M2 and C2S2 supercomplexes, approaching respectively 30 and 28Å resolution, extended by molecular modelling towards the atomic level. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. Copyright © 2013. Published by

  3. On the present status of distribution and threats of high value medicinal plants in the higher altitude forests of the Indian eastern Himalaya

    Directory of Open Access Journals (Sweden)

    P. R. Gajurel

    2015-05-01

    Full Text Available The eastern Himalaya region is a rich repository of medicinal plants.  Excessive collection and unsustainable harvesting of medicinal plants from the wild are leading to a depletion of populations and threatening species in the region.  A study was conducted to explore the diversity, distribution and population status of selected medicinal plants species in the higher altitudes of Arunachal Pradesh, India through extensive field surveys and consultations with the local communities.  Out of about 75 medicinal plants recorded, 41 rare and commercially important medicinal plants were observed in the sub-temperate to alpine forest within an altitudinal range of 1500–4500 m.  Taxonomically these species fall under 25 families of higher plants, of which 31 are dicots, seven are monocots and three gymnosperms.  Many threatened species like Taxus wallichiana, Coptis teeta, Panax pseudoginseng, Panax sikkimensis were recorded in specific localities.  The western part of the state exhibits maximum species diversity.  Out of the various threats observed, improper harvesting, habitat loss and trade are found to be more destructive to the population.  Intensive efforts from both in situ and ex situ conservation practices are necessary for sustainable management and conservation of these species. 

  4. Ab initio calculations of the Fe(II) and Fe(III) isotopic effects in citrates, nicotianamine, and phytosiderophore, and new Fe isotopic measurements in higher plants

    Science.gov (United States)

    Moynier, Frédéric; Fujii, Toshiyuki; Wang, Kun; Foriel, Julien

    2013-05-01

    Iron is one of the most abundant transition metal in higher plants and variations in its isotopic compositions can be used to trace its utilization. In order to better understand the effect of plant-induced isotopic fractionation on the global Fe cycling, we have estimated by quantum chemical calculations the magnitude of the isotopic fractionation between different Fe species relevant to the transport and storage of Fe in higher plants: Fe(II)-citrate, Fe(III)-citrate, Fe(II)-nicotianamine, and Fe(III)-phytosiderophore. The ab initio calculations show firstly, that Fe(II)-nicotianamine is ˜3‰ (56Fe/54Fe) isotopically lighter than Fe(III)-phytosiderophore; secondly, even in the absence of redox changes of Fe, change in the speciation alone can create up to ˜1.5‰ isotopic fractionation. For example, Fe(III)-phytosiderophore is up to 1.5‰ heavier than Fe(III)-citrate2 and Fe(II)-nicotianamine is up to 1‰ heavier than Fe(II)-citrate. In addition, in order to better understand the Fe isotopic fractionation between different plant components, we have analyzed the iron isotopic composition of different organs (roots, seeds, germinated seeds, leaves and stems) from six species of higher plants: the dicot lentil (Lens culinaris), and the graminaceous monocots Virginia wild rye (Elymus virginicus), Johnsongrass (Sorghum halepense), Kentucky bluegrass (Poa pratensis), river oat (Uniola latifolia), and Indian goosegrass (Eleusine indica). The calculations may explain that the roots of strategy-II plants (Fe(III)-phytosiderophore) are isotopically heavier (by about 1‰ for the δ56Fe) than the upper parts of the plants (Fe transported as Fe(III)-citrate in the xylem or Fe(II)-nicotianamine in the phloem). In addition, we suggest that the isotopic variations observed between younger and older leaves could be explained by mixing of Fe received from the xylem and the phloem.

  5. Effects of genetic modifications to flax (Linum usitatissimum) on arbuscular mycorrhiza and plant performance.

    Science.gov (United States)

    Wróbel-Kwiatkowska, Magdalena; Turnau, Katarzyna; Góralska, Katarzyna; Anielska, Teresa; Szopa, Jan

    2012-10-01

    Although arbuscular mycorrhizal fungi (AMF) are known for their positive effect on flax growth, the impact of genetic manipulation in this crop on arbuscular mycorrhiza and plant performance was assessed for the first time. Five types of transgenic flax that were generated to improve fiber quality and resistance to pathogens, through increased levels of either phenylpropanoids (W92.40), glycosyltransferase (GT4, GT5), or PR2 beta-1,3-glucanase (B14) or produce polyhydroxybutyrate (M50), were used. Introduced genetic modifications did not change the degree of mycorrhizal colonization as compared to parent cultivars Linola and Nike. Arbuscules were well developed in each tested transgenic type (except M50). In two lines (W92.40 and B14), a higher abundance of arbuscules was observed when compared to control, untransformed flax plants. However, in some cases (W92.40, GT4, GT5, and B14 Md), the mycorrhizal dependency for biomass production of transgenic plants was slightly lower when compared to the original cultivars. No significant influence of mycorrhiza on the photosynthetic activity of transformed lines was found, but in most cases P concentration in mycorrhizal plants remained higher than in nonmycorrhizal ones. The transformed flax lines meet the demands for better quality of fiber and higher resistance to pathogens, without significantly influencing the interaction with AMF.

  6. Higher plant chloroplasts import the mRNA coding for the eucaryotic translation initiation factor 4E.

    Science.gov (United States)

    Nicolaï, Maryse; Duprat, Anne; Sormani, Rodnay; Rodriguez, Cecilia; Roncato, Marie-Anne; Rolland, Norbert; Robaglia, Christophe

    2007-08-21

    Plant chloroplasts probably originate from an endosymbiosis event between a photosynthetic bacteria and a eucaryotic cell. The proper functioning of this association requires a high level of integration between the chloroplastic genome and the plant cell genome. Many chloroplastic genes have been transferred to the nucleus of the host cell and the proteins coded by these genes are imported into the chloroplast. Chloroplastic activity also regulates the expression of these genes at the transcriptional and post-transcriptional levels. The importation of nucleic acids from the host cell into the chloroplast has never been observed. This work show that the mRNA coding for the eucaryotic translation factor 4E, an essential regulator of translation, enters the chloroplast in four different plant species, and is located in the stroma. Furthermore, the localization in the chloroplast of an heterologous GFP mRNA fused to the eIF4E RNA was also observed.

  7. Identification of genes encoding glycosyltransferases involved in lipopolysaccharide synthesis in Porphyromonas gingivalis.

    Science.gov (United States)

    Shoji, Mikio; Sato, Keiko; Yukitake, Hideharu; Kamaguchi, Arihide; Sasaki, Yuko; Naito, Mariko; Nakayama, Koji

    2017-10-03

    Porphyromonas gingivalis can synthesize both A-LPS and O-LPS, which contain anionic O-polysaccharides and conventional O-polysaccharides, respectively. A-LPS can anchor virulence proteins to the cell surface, and elucidating the mechanism of A-LPS synthesis is therefore important for understanding the pathogenicity of this bacterium. To identify the genes involved in LPS synthesis, we focused on uncharacterized genes encoding the glycosyltransferases, PGN_0361, PGN_ 1239, PGN_1240, and PGN_1668, which were tentatively named gtfC, gtfD, gtfE, and gtfF, respectively, and characterized their mutants. We found that disruption of gtfC and gtfF resulted in A-LPS deficiency. In addition, a gtfD mutant had abnormal A-LPS synthesis, and a gtfE mutant exhibited a rough-type LPS which possesses a short oligosaccharide with lipid A-core. We then constructed a gtfC and gtfD double mutant, since their amino acid sequences are very similar, and this mutant similarly possessed a rough-type LPS. Cross-complementation analysis revealed that the GtfD protein is a functional homolog of the Escherichia coli WbbL protein, which is a rhamnosyltransferase. These results suggested that the GtfE protein is essential for the synthesis of both O-LPS and A-LPS, and that GtfC and GtfD proteins may work together to synthesize the two kinds of LPS. In addition, the GtfF protein was essential for A-LPS synthesis, although this may be achieved in a strain-specific manner. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  8. Exciton modeling of energy-transfer dynamics in the LHCII complex of higher plants: A redfield theory approach

    NARCIS (Netherlands)

    Novoderezhkin, V.; Salverda, J.M.; van Amerongen, H.; van Grondelle, R.

    2003-01-01

    We propose an exciton model for the peripheral plant light-harvesting complex LHCII that allows us to explain the absorption (OD) and linear dichroism (LD) spectra, the superradiance (SR), the pump-probe transient absorption (TA), the three-pulse photon echo peak shift (3PEPS), and transient grating

  9. Exciton modeling of energy-transfer dynamics in the LHCII complex of higher plants: a Redfield theory approach

    NARCIS (Netherlands)

    Novoderezhkin, V.; Salverda, J.M.; Amerongen, van H.; Grondelle, van R.

    2003-01-01

    We propose an exciton model for the peripheral plant light-harvesting complex LHCII that allows us to explain the absorption (OD) and linear dichroism (LD) spectra, the superradiance (SR), the pump-probe transient absorption (TA), the three-pulse photon echo peak shift (3PEPS), and transient grating

  10. Polyamines and cellular metabolism in plants: transgenic approaches reveal different responses to diamine putrescine versus higher polyamines spermidine and spermine

    Science.gov (United States)

    Autar K. Mattoo; Subhash C. Minocha; Rakesh Minocha; Avtar K. Handa

    2010-01-01

    Distribution of biogenic amines--the diamine putrescine (Put), triamine spermidine (Spd), and tetraamine spermine (Spm)--differs between species with Put and Spd being particularly abundant and Spm the least abundant in plant cells. These amines are important for cell viability and their intracellular levels are tightly regulated, which have made it difficult to...

  11. The chromosomal distributions of Ty1-copia group retrotransposable elements in higher plants and their implications for genome evolution

    Science.gov (United States)

    J.S. (Pat) Heslop-Harrison; Andrea Brandes; Shin Taketa; Thomas Schmidt; Alexander V. Vershinin; Elena G. Alkhimova; Anette Kamm; Robert L. Doudrick; . [and others

    1997-01-01

    Retrotransposons make up a major fraction - sometimes more than 40% - of all plant genomes investigated so far. We have isolated the reverse transcriptase domains of theTyl-copia group elements from several species, ranging in genome size from some 100 Mbp to 23,000 Mbp, and determined the distribution patterns of these retrotransposons on metaphase chromosomes and...

  12. A non-enzymatic function of Golgi glycosyltransferases: Mediation of Golgi fragmentation by interaction with non-muscle myosin IIA

    Science.gov (United States)

    Petrosyan, Armen; Cheng, Pi-Wan

    2013-01-01

    The Golgi apparatus undergoes morphological changes under stress or malignant transformation, but the precise mechanisms are not known. We recently showed that non-muscle myosin IIA (NMIIA) binds to the cytoplasmic tail of Core 2 N-acetylglucosaminyltransferase mucus-type (C2GnT-M) and transports it to the endoplasmic reticulum for recycling. Here, we report that Golgi fragmentation induced by brefeldin A (BFA) or coatomer protein (β-COP) knockdown (KD) in Panc1-bC2GnT-M (c-Myc) cells is accompanied by the increased association of NMIIA with C2GnT-M and its degradation by proteasomes. Golgi fragmentation is prevented by inhibition or KD of NMIIA. Using multiple approaches, we have shown that the speed of BFA-induced Golgi fragmentation is positively correlated with the levels of this enzyme in the Golgi. The observation is reproduced in LNCaP cells which express high levels of two endogenous glycosyltransferases—C2GnT-L and β-galactoside α2,3 sialyltransferase 1. NMIIA is found to form complexes with these two enzymes but not Golgi matrix proteins. The KD of both enzymes or the prevention of Golgi glycosyltransferases from exiting endoplasmic reticulum reduced Golgi-associated NMIIA and decreased the BFA-induced fragmentation. Interestingly, the fragmented Golgi detected in colon cancer HT-29 cells can be restored to a compact morphology after inhibition or KD of NMIIA. The Golgi disorganization induced by the microtubule or actin destructive agent is NMIIA-independent and does not affect the levels of glycosyltransferases. We conclude that NMIIA interacts with Golgi residential but not matrix proteins, and this interaction is responsible for Golgi fragmentation induced by β-COP KD or BFA treatment. This is a novel non-enzymatic function of Golgi glycosyltransferases. PMID:23396488

  13. Novel UDP-GalNAc Derivative Structures Provide Insight into the Donor Specificity of Human Blood Group Glycosyltransferase.

    Science.gov (United States)

    Wagner, Gerd K; Pesnot, Thomas; Palcic, Monica M; Jørgensen, Rene

    2015-12-25

    Two closely related glycosyltransferases are responsible for the final step of the biosynthesis of ABO(H) human blood group A and B antigens. The two enzymes differ by only four amino acid residues, which determine whether the enzymes transfer GalNAc from UDP-GalNAc or Gal from UDP-Gal to the H-antigen acceptor. The enzymes belong to the class of GT-A folded enzymes, grouped as GT6 in the CAZy database, and are characterized by a single domain with a metal dependent retaining reaction mechanism. However, the exact role of the four amino acid residues in the specificity of the enzymes is still unresolved. In this study, we report the first structural information of a dual specificity cis-AB blood group glycosyltransferase in complex with a synthetic UDP-GalNAc derivative. Interestingly, the GalNAc moiety adopts an unusual yet catalytically productive conformation in the binding pocket, which is different from the "tucked under" conformation previously observed for the UDP-Gal donor. In addition, we show that this UDP-GalNAc derivative in complex with the H-antigen acceptor provokes the same unusual binding pocket closure as seen for the corresponding UDP-Gal derivative. Despite this, the two derivatives show vastly different kinetic properties. Our results provide a important structural insight into the donor substrate specificity and utilization in blood group biosynthesis, which can very likely be exploited for the development of new glycosyltransferase inhibitors and probes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. UGT74AN1, a Permissive Glycosyltransferase from Asclepias curassavica for the Regiospecific Steroid 3-O-Glycosylation.

    Science.gov (United States)

    Wen, Chao; Huang, Wei; Zhu, Xue-Lin; Li, Xiao-San; Zhang, Fan; Jiang, Ren-Wang

    2018-01-24

    A permissive steroid glycosyltransferase (UGT74AN1) from Asclepias curassavica exhibited robust capabilities for the regiospecific C3 glycosylation of cardiotonic steroids and C21 steroid precursors, and unprecedented promiscuity toward 53 structurally diverse natural and unnatural compounds to form O-, N-, and S-glycosides, along with the catalytic reversibility for a one-pot transglycosylation reaction. These findings highlight UGT74AN1 as the first regiospecific catalyst for cardiotonic steroid C3 glycosylation and exhibit significant potential for glycosylation of diverse bioactive molecules in drug discovery.

  15. A controlled aquatic ecological life support system (CAELSS) for combined production of fish and higher plant biomass suitable for integration into a lunar or planetary base.

    Science.gov (United States)

    Blum, V; Andriske, M; Eichhorn, H; Kreuzberg, K; Schreibman, M P

    1995-10-01

    Based on the construction principle of the already operative Closed Equilibrated Biological Aquatic System (C.E.B.A.S.) the concept of an aquaculture system for combined production of animal and plant biomass was developed. It consists of a tank for intensive fish culture which is equipped with a feeding lock representing also a trap for biomass removal followed by a water recycling system. This is an optimized version of the original C.E.B.A.S. filters adapted to higher water pollutions. It operates in a fully biological mode and is able to convert the high ammonia ion concentrations excreted by the fish gills into nitrite ions. The second biomass production site is a higher plant cultivator with an internal fiber optics light distributor which may utilize of solar energy. The selected water plant is a tropical rootless duckweed of the genus Wolffia which possesses a high capacity in nitrate elimination and is terrestrially cultured as a vegetable for human nutrition in Southeast Asia. It is produced in an improved suspension culture which allows the removal of excess biomass by tangential centrifugation. The plant cultivator is able to supply the whole system with oxygen for respiration and eliminates vice versa the carbon dioxide exhaled by the fish via photosynthesis. A gas exchanger may be used for emergency purposes or to deliver excess oxygen into the environment and may be implemented into the air regeneration system of a closed environment of higher order. The plant biomass is fed into a biomass processor which delivers condensed fresh and dried biomass as pellets. The recovered water is fed back into the aquaculture loop. The fresh plants can be used for human nutrition immediately or can be stored after sterilization in an adequate packing. The dried Wolffia pellets are collected and brought into the fish tank by an automated feeder. In parallel the water from the plant cultivator is driven back to the animal tank by a pump. The special feature of the

  16. Development of a simple PCR-based assay for the identification of triazine resistance in the noxious plant common ragweed (Ambrosia artemisiifolia) and its applicability in higher plants.

    Science.gov (United States)

    Mátyás, Kinga Klára; Taller, János; Cseh, András; Poczai, Péter; Cernák, István

    2011-12-01

    Bidirectional allele-specific PCR (Bi-PASA) was used to detect a point mutation causing triazine resistance in common ragweed (Ambrosia artemisiifolia). The external primers amplified a 278 bp standard DNA fragment in all genotypes. In the susceptible S264S genotypes, a 208 bp fragment was expected while in resistant S264G common ragweed genotypes a 109 bp band was expected. In resistant plants, both the wild and mutant type fragments were detected, indicating that the original triazine sensitive cpDNA is maintained in a heteroplasmic state in the resistant S264G genotypes. Additionally, in silico analysis confirmed the potential applicability of our diagnostic assay for other plant species. In 24 out of 74 taxa (32%), the assay could be used without any change, while in the others some of the primers should be redesigned before use. © Springer Science+Business Media B.V. 2011

  17. From genes to shape: understanding the control of morphogenesis at the shoot meristem in higher plants using systems biology.

    Science.gov (United States)

    Traas, Jan; Hamant, Olivier

    2009-11-01

    The shoot apical meristem is a population of stem cells which controls the initiation of leaves, flowers and branches during the entire life of the plant. Although we have gained significant new insight in the nature of the genetic networks and cellular processes that control meristem function, major questions have remained unsolved. It has been difficult, for instance, to define the precise role of genetic determinants in controlling morphogenesis and the control of shape is currently a major and largely unresolved issue in plant biology. This is a difficult task, notably because it is close to impossible to predict the activity of a single gene, in a context where thousands of genes interact. Systems biology has emerged as a powerful tool to address this type of issue. Systems biology analyses processes such as plant development at different scales, describing not only the properties of individual cells but also their interactions. The complexity of the information involved is such, that it cannot be understood and integrated on a purely intuitive basis. For this reason, building on the acquisition of quantitative data, computer models have become more and more important. The first models have begun to reproduce gene network behaviours and dynamical shape changes, providing new insight in the control of morphogenesis.

  18. Requirements of blue, UV-A, and UV-B light for normal growth of higher plants, as assessed by actions spectra for growth and related phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, T. [Kobe Women`s Univ., Higashisuma (Japan)

    1994-12-31

    It is very important for experimental purposes, as well as for the practical use of plants when not enough sunlight is available. To grow green higher plants in their normal forms under artificial lighting constructing efficient and economically reasonable lighting systems is not an easy task. One possible approach would be to simulate sunlight in intensity and the radiation spectrum, but its high construction and running costs are not likely to allow its use in practice. Sunlight may be excessive in irradiance in some or all portions of the spectrum. Reducing irradiance and removing unnecessary wavebands might lead to an economically feasible light source. However, removing or reducing a particular waveband from sunlight for testing is not easy. Another approach might be to find the wavebands required for respective aspects of plant growth and to combine them in a proper ratio and intensity. The latter approach seems more practical and economical, and the aim of this Workshop lies in advancing this approach. I summarize our present knowledge on the waveband requirements of higher plants for the regions of blue, UV-A and UV-B.

  19. Stable isotopes of Cu and Zn in higher plants: evidence for Cu reduction at the root surface and two conceptual models for isotopic fractionation processes.

    Science.gov (United States)

    Jouvin, D; Weiss, D J; Mason, T F M; Bravin, M N; Louvat, P; Zhao, F; Ferec, F; Hinsinger, P; Benedetti, M F

    2012-03-06

    Recent reports suggest that significant fractionation of stable metal isotopes occurs during biogeochemical cycling and that the uptake into higher plants is an important process. To test isotopic fractionation of copper (Cu) and zinc (Zn) during plant uptake and constrain its controls, we grew lettuce, tomato, rice and durum wheat under controlled conditions in nutrient solutions with variable metal speciation and iron (Fe) supply. The results show that the fractionation patterns of these two micronutrients are decoupled during the transport from nutrient solution to root. In roots, we found an enrichment of the heavier isotopes for Zn, in agreement with previous studies, but an enrichment of isotopically light Cu, suggesting a reduction of Cu(II) possibly at the surfaces of the root cell plasma membranes. This observation holds for both graminaceous and nongraminaceaous species and confirms that reduction is a predominant and ubiquitous mechanism for the acquisition of Cu into plants similar to the mechanism for the acquisition of iron (Fe) by the strategy I plant species. We propose two preliminary models of isotope fractionation processes of Cu and Zn in plants with different uptake strategies.

  20. The inhibition of liposaccharide heptosyltransferase WaaC with multivalent glycosylated fullerenes: a new mode of glycosyltransferase inhibition.

    Science.gov (United States)

    Durka, Maxime; Buffet, Kevin; Iehl, Julien; Holler, Michel; Nierengarten, Jean-François; Vincent, Stéphane P

    2012-01-09

    L,D-Heptosides (L-glycero-D-manno-heptopyranoses) are found in important bacterial glycolipids such as lipopolysaccharide (LPS), the biosynthesis of which is targeted for the development of novel antibacterial agents. This work describes the synthesis of a series of fullerene hexa-adducts bearing 12 copies of peripheral sugars displaying the mannopyranose core structure of bacterial L,D-heptoside. The multimers were assembled through an efficient copper-catalyzed alkyne-azide cycloaddition reaction as the final step. The final fullerene sugar balls were assayed as inhibitors of heptosyltransferase WaaC, the glycosyltransferase catalyzing the incorporation of the first L-heptose into LPS. Interestingly, the inhibition of the final molecules was found in the low micromolar range (IC(50) =7-45 μM), whereas the corresponding monomeric glycosides displayed high micromolar to low millimolar inhibition levels (IC(50) always above 400 μM). When evaluated on a "per-sugar" basis, these inhibition data showed that, in each case, the average affinity of a single glycoside of the fullerenes towards WaaC was significantly enhanced when displayed as a multimer, thus demonstrating an unexpected multivalent effect. To date, such a multivalent mode of inhibition had never been evidenced with glycosyltransferases. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Exploiting the aglycon promiscuity of glycosyltransferase Bs-YjiC from Bacillus subtilis and its application in synthesis of glycosides.

    Science.gov (United States)

    Dai, Longhai; Li, Jiao; Yao, Peiyuan; Zhu, Yueming; Men, Yan; Zeng, Yan; Yang, Jiangang; Sun, Yuanxia

    2017-04-20

    Glycosylation is a prominent biological mechanism for structural and functional diversity of natural products. Uridine diphosphate-dependent glycosyltransferases with aglycon promiscuity are generally recognised as effective biocatalysts for glycodiversification of natural products for practical applications. In this study, the aglycon promiscuity of glycosyltransferase Bs-YjiC from Bacillus subtilis 168 was explored. Bs-YjiC, with uridine diphosphate glucose (UDPG) as sugar donor, exhibited robust capabilities to glycosylate 19 structurally diverse types of drug-like scaffolds with regio- and stereospecificities and form O-, N- and S-linkage glycosides. Twenty-four glycosides of 17 aglycons were purified from scale-up reactions using Bs-YjiC as a biocatalyst, and their structures were confirmed by nuclear magnetic resonance spectra. Furthermore, a one-pot reaction by coupling Bs-YjiC to sucrose synthase from Arabidopsis thaliana was applied to glycosylate pterostilbene. Without adding the costly UDPG as sugar donor, 9mM (3.8g/L) pterostilbene 4'-O-β-glucoside was obtained by periodic feeding of pterostilbene. These results suggest the aglycon promiscuity of Bs-YjiC and demonstrate its significant application prospect in biosynthesis of valuable natural products. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A Novel Cyclodextrin Glycosyltransferase from Alkaliphilic Amphibacillus sp. NPST-10: Purification and Properties

    Directory of Open Access Journals (Sweden)

    Garabed Antranikian

    2012-08-01

    Full Text Available Screening for cyclodextrin glycosyltransferase (CGTase-producing alkaliphilic bacteria from samples collected from hyper saline soda lakes (Wadi Natrun Valley, Egypt, resulted in isolation of potent CGTase producing alkaliphilic bacterium, termed NPST-10. 16S rDNA sequence analysis identified the isolate as Amphibacillus sp. CGTase was purified to homogeneity up to 22.1 fold by starch adsorption and anion exchange chromatography with a yield of 44.7%. The purified enzyme was a monomeric protein with an estimated molecular weight of 92 kDa using SDS-PAGE. Catalytic activities of the enzyme were found to be 88.8 U mg−1 protein, 20.0 U mg−1 protein and 11.0 U mg−1 protein for cyclization, coupling and hydrolytic activities, respectively. The enzyme was stable over a wide pH range from pH 5.0 to 11.0, with a maximal activity at pH 8.0. CGTase exhibited activity over a wide temperature range from 45 °C to 70 °C, with maximal activity at 50 °C and was stable at 30 °C to 55 °C for at least 1 h. Thermal stability of the purified enzyme could be significantly improved in the presence of CaCl2. Km and Vmax values were estimated using soluble starch as a substrate to be 1.7 ± 0.15 mg/mL and 100 ± 2.0 μmol/min, respectively. CGTase was significantly inhibited in the presence of Co2+, Zn2+, Cu2+, Hg2+, Ba2+, Cd2+, and 2-mercaptoethanol. To the best of our knowledge, this is the first report of CGTase production by Amphibacillus sp. The achieved high conversion of insoluble raw corn starch into cyclodextrins (67.2% with production of mainly β-CD (86.4%, makes Amphibacillus sp. NPST-10 desirable for the cyclodextrin production industry.

  3. A novel cyclodextrin glycosyltransferase from Alkaliphilic Amphibacillus sp. NPST-10: purification and properties.

    Science.gov (United States)

    Ibrahim, Abdelnasser S S; Al-Salamah, Ali A; El-Tayeb, Mohamed A; El-Badawi, Yahya B; Antranikian, Garabed

    2012-01-01

    Screening for cyclodextrin glycosyltransferase (CGTase)-producing alkaliphilic bacteria from samples collected from hyper saline soda lakes (Wadi Natrun Valley, Egypt), resulted in isolation of potent CGTase producing alkaliphilic bacterium, termed NPST-10. 16S rDNA sequence analysis identified the isolate as Amphibacillus sp. CGTase was purified to homogeneity up to 22.1 fold by starch adsorption and anion exchange chromatography with a yield of 44.7%. The purified enzyme was a monomeric protein with an estimated molecular weight of 92 kDa using SDS-PAGE. Catalytic activities of the enzyme were found to be 88.8 U mg(-1) protein, 20.0 U mg(-1) protein and 11.0 U mg(-1) protein for cyclization, coupling and hydrolytic activities, respectively. The enzyme was stable over a wide pH range from pH 5.0 to 11.0, with a maximal activity at pH 8.0. CGTase exhibited activity over a wide temperature range from 45 °C to 70 °C, with maximal activity at 50 °C and was stable at 30 °C to 55 °C for at least 1 h. Thermal stability of the purified enzyme could be significantly improved in the presence of CaCl(2). K(m) and V(max) values were estimated using soluble starch as a substrate to be 1.7 ± 0.15 mg/mL and 100 ± 2.0 μmol/min, respectively. CGTase was significantly inhibited in the presence of Co(2+), Zn(2+), Cu(2+), Hg(2+), Ba(2+), Cd(2+), and 2-mercaptoethanol. To the best of our knowledge, this is the first report of CGTase production by Amphibacillus sp. The achieved high conversion of insoluble raw corn starch into cyclodextrins (67.2%) with production of mainly β-CD (86.4%), makes Amphibacillus sp. NPST-10 desirable for the cyclodextrin production industry.

  4. Monoterpenyl Glycosyltransferases Differentially Contribute to Production of Monoterpenyl Glycosides in Two Aromatic Vitis vinifera Varieties.

    Science.gov (United States)

    Li, Xiang-Yi; Wen, Ya-Qin; Meng, Nan; Qian, Xu; Pan, Qiu-Hong

    2017-01-01

    HIGHLIGHTS A similar trend on accumulation of glycosidically bound monoterpenes was observed in both varietiesTwo VvGT7 alleles mutations occurred at key sites in Muscat blanc à PetitVvGT14 exerted a major role in production of monoterpenyl glycosides in both varieties Terpenoids are the major aroma components and generally exist as both free and glycosidically-bound forms, of which nonvolatile glycosides account for a large fraction in grape berries. Our previous study has indicated that differential accumulation of monoterpenyl glycosides in Vitis vinifera "Muscat blanc à Petit" between two regions is closely correlated to monoterpenyl glucosyltransferase (VvGT14, XM_002285734.2) transcript abundance. However, it has not been determined yet whether this correlation also exists in other Vitis vinifera varieties. This study investigated the evolution of free and glycosidically bound monoterpenes in two Vitis vinifera variety "Muscat blanc à Petit" and "Gewurztraminer" under two vintages, and further assessed the relation between the accumulation of bound monoterpenes and two monoterpenyl glycosyltransferase transcript levels. Results showed that free monoterpenes exhibited three evolution patterns in both varieties during berry development of two vintages, whereas glycosidically bound monoterpenes showed a concentration elevation with berry maturation. The Cis-rose oxide and geraniol were major components contributing to the aroma odors of "Gewürztraminer" grapes while linalool was major aroma contributor to the "Muscat blanc à Petit grain" grapes. The accumulation of glycosidically bound monoterpenes in both varieties was accompanied with the high expression of VvGT7 (XM_002276510.2) and VvGT14. Only one allele of VvGT7 was found in the variety "Gewürztraminer" and no mutation was observed in its enzyme active sites. XB-VvGT7-4 and XB-VvGT7-5 were two alleles of VvGT7 detected in "Muscat blanc à Petit grain." The mutation on its enzyme active site inhibited

  5. Risks of increased UV-B radiation: higher plants; Risiken erhoehter UV-B-Strahlung: Hoehere Pflanzen

    Energy Technology Data Exchange (ETDEWEB)

    Rau, W. [Muenchen Univ. (Germany). Botanisches Inst.; Hofmann, H. [Muenchen Univ. (Germany). Botanisches Inst.

    1994-03-01

    The question pursued within the Bavarian climate research programme (BayFORKLIM) in the present context was as follows: Does the fact that UV-B radiation increases with growing site elevation mean that the low sensitivity of predominantly alpine plants compared with that of lowland plants is attributable to their different genetic constitution, possibly as a result of selective pressure and/or de alpine species have a greater capacity to develop protective mechanisms? Pairs and triplets of species belonging to the same genus but occuring at different site elevations were grown from seeds in a greenhouse that is, without UV-B. In order to determine their capacity to adapt to UV-B radiation, some of the plants were additionally exposed to UV-B for 5-6 weeks prior to sensitivity testing. Sensitivity was tested by exposing the plants to additional UV-B of different intensities in test chambers. Visible damage, ranging from light bronzing or yellowing to withering, served as an assessment criterion. Levels of UV-B absorbing substances (phenylpropane species, usually flavonoids) were also measured in these plants. The results obtained permit the following conclusions: The greater UV-B resistance of alpine species compared with that of lowland species of the same genus is not attributable to their genetic constitution but rather to their superior adaptability. Superior resistance is in part due to a greater accumulation of UV-B absorbing substances. Distinct differences in sensitivity between different genera could lead to population shifts within ecosystems as a result of increased UV-B radiation. (orig./KW) [Deutsch] Die Fragestellung, die im Rahmen des Bayerischen Klimaforschungsprogramms (BayFORKLIM) bearbeitet wurde, ist folgende: Die UV-B-Strahlung nimmt mit der Hoehe ueber dem Meeresspiegel zu; sind deshalb Pflanzenarten, die bevorzugt in alpinen Habitaten vorkommen, durch ihre genetische Konstitution - moeglicherweise durch Selektion erworben - weniger UV

  6. Torrefaction of invasive alien plants: Influence of heating rate and other conversion parameters on mass yield and higher heating value.

    Science.gov (United States)

    Mundike, Jhonnah; Collard, François-Xavier; Görgens, Johann F

    2016-06-01

    With the aim of controlling their proliferation, two invasive alien plants, Lantana camara (LC) and Mimosa pigra (MP), both widespread in Africa, were considered for torrefaction for renewable energy applications. Using thermogravimetric analysis, the influence of heating rate (HR: 2.18-19.82°Cmin(-1)) together with variable temperature and hold time on char yield and HHV (in a bomb calorimeter) were determined. Statistically significant effects of HR on HHV with optima at 10.5°Cmin(-1) for LC and 20°Cmin(-1) for MP were obtained. Increases of HHV up to 0.8MJkg(-1) or energy yield greater than 10%, together with a 3-fold reduction in torrefaction conversion time could be achieved by optimisation of HR. Analysis of the torrefaction volatiles by TG-MS showed that not only hemicelluloses, but also lignin conversion, could influence the optimum HR value. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Towards systems biology of the gravity response of higher plants -multiscale analysis of Arabidopsis thaliana root growth

    Science.gov (United States)

    Palme, Klaus; Aubry, D.; Bensch, M.; Schmidt, T.; Ronneberger, O.; Neu, C.; Li, X.; Wang, H.; Santos, F.; Wang, B.; Paponov, I.; Ditengou, F. A.; Teale, W. T.; Volkmann, D.; Baluska, F.; Nonis, A.; Trevisan, S.; Ruperti, B.; Dovzhenko, A.

    Gravity plays a fundamental role in plant growth and development. Up to now, little is known about the molecular organisation of the signal transduction cascades and networks which co-ordinate gravity perception and response. By using an integrated systems biological approach, a systems analysis of gravity perception and the subsequent tightly-regulated growth response is planned in the model plant Arabidopsis thaliana. This approach will address questions such as: (i) what are the components of gravity signal transduction pathways? (ii) what are the dynamics of these components? (iii) what is their spatio-temporal regulation in different tis-sues? Using Arabidopsis thaliana as a model-we use root growth to obtain insights in the gravity response. New techniques enable identification of the individual genes affected by grav-ity and further integration of transcriptomics and proteomics data into interaction networks and cell communication events that operate during gravitropic curvature. Using systematic multiscale analysis we have identified regulatory networks consisting of transcription factors, the protein degradation machinery, vesicle trafficking and cellular signalling during the gravire-sponse. We developed approach allowing to incorporate key features of the root system across all relevant spatial and temporal scales to describe gene-expression patterns and correlate them with individual gene and protein functions. Combination of high-resolution microscopy and novel computational tools resulted in development of the root 3D model in which quantitative descriptions of cellular network properties and of multicellular interactions important in root growth and gravitropism can be integrated for the first time.

  8. Diets higher in animal and plant protein are associated with lower adiposity and do not impair kidney function in US adults.

    Science.gov (United States)

    Berryman, Claire E; Agarwal, Sanjiv; Lieberman, Harris R; Fulgoni, Victor L; Pasiakos, Stefan M

    2016-09-01

    Higher-protein diets are associated with decreased adiposity and greater HDL cholesterol than lower protein diets. Whether these benefits can be attributed to a specific protein source (i.e., nondairy animal, dairy, or plant) is unknown, and concerns remain regarding the impact of higher-protein diets on kidney function. The objective of this study was to evaluate trends of protein source on markers of cardiometabolic disease risk and kidney function in US adults. Total, nondairy animal, dairy, and plant protein intake were estimated with the use of 24-h recall data from NHANES 2007-2010 (n = 11,111; ≥19 y). Associations between source-specific protein intake and health outcomes were determined with the use of models that adjusted for sex, race and ethnicity, age, physical activity, poverty-to-income ratio, individual intake (grams per kilogram) for each of the other 2 protein sources, body mass index (BMI) (except for weight-related variables), and macronutrient (carbohydrate, fiber, and total and saturated fat) intake. Mean ± SE total protein intake was 82.3 ± 0.8 g/d (animal: 37.4 ± 0.5 g/d; plant: 24.7 ± 0.3 g/d; and dairy: 13.4 ± 0.3 g/d). Both BMI and waist circumference were inversely associated [regression coefficient (95% CI)] with animal [-0.199 (-0.265, -0.134), P protein intake. Blood urea nitrogen concentrations increased across deciles for animal [0.313 (0.248, 0.379), P protein intake. Glomerular filtration rate and blood creatinine were not associated with intake of any protein source. Diets higher in plant and animal protein, independent of other dietary factors, are associated with cardiometabolic benefits, particularly improved central adiposity, with no apparent impairment of kidney function. © 2016 American Society for Nutrition.

  9. Diacylglycerol Kinases Are Widespread in Higher Plants and Display Inducible Gene Expression in Response to Beneficial Elements, Metal, and Metalloid Ions.

    Science.gov (United States)

    Escobar-Sepúlveda, Hugo F; Trejo-Téllez, Libia I; Pérez-Rodríguez, Paulino; Hidalgo-Contreras, Juan V; Gómez-Merino, Fernando C

    2017-01-01

    Diacylglycerol kinases (DGKs) are pivotal signaling enzymes that phosphorylate diacylglycerol (DAG) to yield phosphatidic acid (PA). The biosynthesis of PA from phospholipase D (PLD) and the coupled phospholipase C (PLC)/DGK route is a crucial signaling process in eukaryotic cells. Next to PLD, the PLC/DGK pathway is the second most important generator of PA in response to biotic and abiotic stresses. In eukaryotic cells, DGK, DAG, and PA are implicated in vital processes such as growth, development, and responses to environmental cues. A plethora of DGK isoforms have been identified so far, making this a rather large family of enzymes in plants. Herein we performed a comprehensive phylogenetic analysis of DGK isoforms in model and crop plants in order to gain insight into the evolution of higher plant DGKs. Furthermore, we explored the expression profiling data available in public data bases concerning the regulation of plant DGK genes in response to beneficial elements and other metal and metalloid ions, including silver (Ag), aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and sodium (Na). In all plant genomes explored, we were able to find DGK representatives, though in different numbers. The phylogenetic analysis revealed that these enzymes fall into three major clusters, whose distribution depends on the composition of structural domains. The catalytic domain conserves the consensus sequence GXGXXG/A where ATP binds. The expression profiling data demonstrated that DGK genes are rapidly but transiently regulated in response to certain concentrations and time exposures of beneficial elements and other ions in different plant tissues analyzed, suggesting that DGKs may mediate signals triggered by these elements. Though this evidence is conclusive, further signaling cascades that such elements may stimulate during hormesis, involving the phosphoinositide signaling pathway and DGK genes and enzymes, remain to be elucidated.

  10. Generation of poly-β-hydroxybutyrate from acetate in higher plants: Detection of acetoacetyl CoA reductase- and PHB synthase- activities in rice.

    Science.gov (United States)

    Tsuda, Hirohisa; Shiraki, Mari; Inoue, Eri; Saito, Terumi

    2016-08-20

    It has been reported that Poly-β-hydroxybutyrate (PHB) is generated from acetate in the rice root. However, no information is available about the biosynthetic pathway of PHB from acetate in plant cells. In the bacterium Ralstonia eutropha H16 (R. eutropha), PHB is synthesized from acetyl CoA by the consecutive reaction of three enzymes: β-ketothiolase (EC: 2.3.1.9), acetoacetyl CoA reductase (EC: 1.1.1.36) and PHB synthase (EC: 2.3.1.-). Thus, in this study, we examined whether the above three enzymatic activities were also detected in rice seedlings. The results clearly showed that the activities of the above three enzymes were all detected in rice. In particular, the PHB synthase activity was detected specifically in the sonicated particulate fractions (2000g 10min precipitate (ppt) and the 8000g 30min ppt) of rice roots and leaves. In addition to these enzyme activities, several new experimental results were obtained on PHB synthesis in higher plants: (a) (14)C-PHB generated from 2-(14)C-acetate was mainly localized in the 2000g 10min ppt and the 8000g 30min ppt of rice root. (b) Addition of acetate (0.1-10mM) to culture medium of rice seedlings did not increase the content of PHB in the rice root or leaf. (c) In addition to C3 plants, PHB was generated from acetate in a C4 plant (corn) and in a CAM plant (Bryophyllum pinnatum). d) Washing with ethylenediaminetetraacetic acid (EDTA) strongly suggested that the PHB synthesized from acetate was of plant origin and was not bacterial contamination. Copyright © 2016 Elsevier GmbH. All rights reserved.

  11. [Use of feed mixture with a higher content of plant proteins in piglets during the weaning period].

    Science.gov (United States)

    Herzig, I; Dvorák, M; Toulová, M

    1976-12-01

    Two experiments with 56 piglets and pilot trial on 84 piglets were performed to demonstrate that it is possible to replace the complete mixture for early piglet weaning (COS-1, or COS-2) by an experimental mixture without fish meal, with a higher proportion of soya and maize, supplemented by lysine and methionine; this mixture is to be fed to piglets in the weaning period. The weight gain dropped in both basic experiments after weaning, especially in the group with a higher content of nitrogenous matters in the diet. No significant inter-group differences were found in the activity of enzymes in serum and in liver, nor were they found in the adrenocortical activity.

  12. Structures of maltohexaose and maltoheptaose bound at the donor sites of cyclodextrin glycosyltransferase give insight into the mechanisms of transglycosylation activity and cyclodextrin size specificity

    NARCIS (Netherlands)

    Uitdehaag, JCM; van Alebeek, GJWM; Dijkhuizen, L; Dijkstra, BW; Alebeek, Gert-Jan W.M. van; Dijkstra, Bauke W.

    2000-01-01

    The enzymes from the cl-amylase family all share a similar alpha-retaining catalytic mechanism but can have different reaction and product specificities. One family member, cyclodextrin glycosyltransferase (CGTase), has an uncommonly high transglycosylation activity and is able to form

  13. The cyclization mechanism of cyclodextrin glycosyltransferase (CGTase) as revealed by a gamma-cyclodextrin-CGTase complex at 1.8-angstrom resolution

    NARCIS (Netherlands)

    Uitdehaag, JCM; Kalk, KH; Dijkhuizen, L; Dijkstra, BW

    1999-01-01

    The enzyme cyclodextrin glycosyltransferase is closely related to alpha-amylases but has the unique ability to produce cyclodextrins (circular alpha(1-->4)-linked glucoses) from starch. To characterize this specificity we determined a 1.8-Angstrom structure of an E257Q/D229N mutant cyclodextrin

  14. Land plants drive photorespiration as higher electron-sink: comparative study of post-illumination transient O2 -uptake rates from liverworts to angiosperms through ferns and gymnosperms.

    Science.gov (United States)

    Hanawa, Hitomi; Ishizaki, Kimitsune; Nohira, Kana; Takagi, Daisuke; Shimakawa, Ginga; Sejima, Takehiro; Shaku, Keiichiro; Makino, Amane; Miyake, Chikahiro

    2017-09-01

    In higher plants, the electron-sink capacity of photorespiration contributes to alleviation of photoinhibition by dissipating excess energy under conditions when photosynthesis is limited. We addressed the question at which point in the evolution of photosynthetic organisms photorespiration began to function as electron sink and replaced the flavodiiron proteins which catalyze the reduction of O2 at photosystem I in cyanobacteria. Algae do not have a higher activity of photorespiration when CO2 assimilation is limited, and it can therefore not act as an electron sink. Using land plants (liverworts, ferns, gymnosperms, and angiosperms) we compared photorespiration activity and estimated the electron flux driven by photorespiration to evaluate its electron-sink capacity at CO2 -compensation point. In vivo photorespiration activity was estimated by the simultaneous measurement of O2 -exchange rate and chlorophyll fluorescence yield. All C3-plants leaves showed transient O2 -uptake after actinic light illumination (post-illumination transient O2 -uptake), which reflects photorespiration activity. Post-illumination transient O2 -uptake rates increased in the order from liverworts to angiosperms through ferns and gymnosperms. Furthermore, photorespiration-dependent electron flux in photosynthetic linear electron flow was estimated from post-illumination transient O2 -uptake rate and compared with the electron flux in photosynthetic linear electron flow in order to evaluate the electron-sink capacity of photorespiration. The electron-sink capacity at the CO2 -compensation point also increased in the above order. In gymnosperms photorespiration was determined to be the main electron-sink. C3-C4 intermediate species of Flaveria plants showed photorespiration activity, which intermediate between that of C3- and C4-flaveria species. These results indicate that in the first land plants, liverworts, photorespiration started to function as electron sink. According to our

  15. Volatile metabolites of higher plant crops as a photosynthesizing life support system component under temperature stress at different light intensities

    Science.gov (United States)

    Gitelson, I. I.; Tikhomirov, A. A.; Parshina, O. V.; Ushakova, S. A.; Kalacheva, G. S.

    The effect of elevated temperatures of 35 and 45°C (at the intensities of photosynthetically active radiation 322, 690 and 1104 μmol·m -2·s -1) on the photosynthesis, respiration, and qualitative and quantitative composition of the volatiles emitted by wheat ( Triticum aestuvi L., cultivar 232) crops was investigated in growth chambers. Identification and quantification of more than 20 volatile compounds (terpenoids-α-pinene, Δ3 carene, limonene, benzene, α-and trans-caryophyllene, α- and γ-terpinene, their derivatives, aromatic hydrocarbons, etc.) were conducted by gas chromatograph/mass spectrometry. Under light intensity of 1104 μmol·m -2·s -1 heat resistance of photosynthesis and respiration increased at 35°C and decreased at 45°C. The action of elevated temperatures brought about variations in the rate and direction of the synthesis of volatile metabolites. The emission of volatile compounds was the greatest under a reduced irradiation of 322 μmol·m -2·s -1 and the smallest under 1104 μmol·m -2·s -1, at 35°C. During the repair period, the contents and proportions of volatile compounds were different from their initial values, too. The degree of disruption and the following recovery of the functional state depended on the light intensity during the exposure to elevated temperatures. The investigation of the atmosphere of the growth chamber without plants has revaled the substances that were definitely technogenic in origin: tetramethylurea, dimethylsulfide, dibutylsulfide, dibutylphthalate, and a number of components of furan and silane nature.

  16. Isotopic niche variation in a higher trophic level ectotherm: highlighting the role of succulent plants in desert food webs.

    Science.gov (United States)

    Delibes, Miguel; Blazquez, Ma Carmen; Fedriani, Jose Maria; Granados, Arsenio; Soriano, Laura; Delgado, Antonio

    2015-01-01

    Stable isotope analysis of animal tissues allows description of isotopic niches, whose axes in an n-dimensional space are the isotopic ratios, compared to a standard, of different isotope systems (e.g. δ(13)C, δ(15)N). Isotopic niches are informative about where an animal, population or species lives and about what it consumes. Here we describe inter- and intrapopulation isotopic niche (bidimensional δ(13)C-δ(15)N space) of the Orange-throated whiptail (Aspidoscelis hyperythra), an arthropodivorous small lizard, in ten localities of Baja California Sur (Mexico). These localities range from extreme arid to subtropical conditions. Between 13 and 20 individuals were sampled at each locality and 1 cm of tail-tip was collected for isotope analysis. As expected, interpopulation niche width variation was much larger than intrapopulation one. Besides, isotopic variation was not related to age, sex or individual size of lizards. This suggests geographic variation of the isotopic niche was related to changes in the basal resources that fuel the trophic web at each locality. The position of Bayesian isotope ellipses in the δ-space indicated that whiptails in more arid localities were enriched in 13C, suggesting most of the carbon they ingested came from CAM succulent plants (cacti, agaves) and in minor degree in C4 grasses. Contrarily, whiptails in subtropical areas were depleted in 13C, as they received more carbon from C3 scrubs and trees. Localities closer to sea-level tended to be enriched in 15N, but a clear influence of marine subsidies was detected only at individual level. The study contributes to identify the origin and pathways through which energy flows across the trophic webs of North American deserts.

  17. Isotopic niche variation in a higher trophic level ectotherm: highlighting the role of succulent plants in desert food webs.

    Directory of Open Access Journals (Sweden)

    Miguel Delibes

    Full Text Available Stable isotope analysis of animal tissues allows description of isotopic niches, whose axes in an n-dimensional space are the isotopic ratios, compared to a standard, of different isotope systems (e.g. δ(13C, δ(15N. Isotopic niches are informative about where an animal, population or species lives and about what it consumes. Here we describe inter- and intrapopulation isotopic niche (bidimensional δ(13C-δ(15N space of the Orange-throated whiptail (Aspidoscelis hyperythra, an arthropodivorous small lizard, in ten localities of Baja California Sur (Mexico. These localities range from extreme arid to subtropical conditions. Between 13 and 20 individuals were sampled at each locality and 1 cm of tail-tip was collected for isotope analysis. As expected, interpopulation niche width variation was much larger than intrapopulation one. Besides, isotopic variation was not related to age, sex or individual size of lizards. This suggests geographic variation of the isotopic niche was related to changes in the basal resources that fuel the trophic web at each locality. The position of Bayesian isotope ellipses in the δ-space indicated that whiptails in more arid localities were enriched in 13C, suggesting most of the carbon they ingested came from CAM succulent plants (cacti, agaves and in minor degree in C4 grasses. Contrarily, whiptails in subtropical areas were depleted in 13C, as they received more carbon from C3 scrubs and trees. Localities closer to sea-level tended to be enriched in 15N, but a clear influence of marine subsidies was detected only at individual level. The study contributes to identify the origin and pathways through which energy flows across the trophic webs of North American deserts.

  18. Sequence organization and putative regulatory elements in the 5S rRNA genes of two higher plants (Vigna radiata and Matthiola incana).

    Science.gov (United States)

    Hemleben, V; Werts, D

    1988-01-01

    The tandemly arranged and clustered highly repeated 5S rRNA genes are investigated for two plants belonging to different higher plant families: Matthiola incana (Brassicaceae, Dilleniidae, Rosidae; 3600 5S rRNA genes/n) shows a homogeneous repeat size of 510 bp, whereas Vigna radiata (mung bean, former Phaseolus aureus, Fabaceae, Rosidae; approx. 4300 5S rRNA genes) has a repeat size of 215 bp. The mung-bean 5S rRNA coding region starts 5' with AGG and ends with CCT; Matthiola starts with GGG and ends with CCC. Striking is the strict occurrence of a 'TATA' box starting at nucleotide-28 similar to Neurospora crassa 5S rRNA genes. The 3' end is followed by CTTTT or GTTT stretches present in different numbers in the non-transcribed spacer suggesting a function in termination.

  19. The Abundance of Endofungal Bacterium Rhizobium radiobacter (syn. Agrobacterium tumefaciens) Increases in Its Fungal Host Piriformospora indica during the Tripartite Sebacinalean Symbiosis with Higher Plants.

    Science.gov (United States)

    Guo, Huijuan; Glaeser, Stefanie P; Alabid, Ibrahim; Imani, Jafargholi; Haghighi, Hossein; Kämpfer, Peter; Kogel, Karl-Heinz

    2017-01-01

    Rhizobium radiobacter (syn. Agrobacterium tumefaciens, syn. "Agrobacterium fabrum") is an endofungal bacterium of the fungal mutualist Piriformospora (syn. Serendipita) indica (Basidiomycota), which together form a tripartite Sebacinalean symbiosis with a broad range of plants. R. radiobacter strain F4 (RrF4), isolated from P. indica DSM 11827, induces growth promotion and systemic resistance in cereal crops, including barley and wheat, suggesting that R. radiobacter contributes to a successful symbiosis. Here, we studied the impact of endobacteria on the morphology and the beneficial activity of P. indica during interactions with plants. Low numbers of endobacteria were detected in the axenically grown P. indica (long term lab-cultured, lcPiri) whereas mycelia colonizing the plant root contained increased numbers of bacteria. Higher numbers of endobacteria were also found in axenic cultures of P. indica that was freshly re-isolated (riPiri) from plant roots, though numbers dropped during repeated axenic re-cultivation. Prolonged treatments of P. indica cultures with various antibiotics could not completely eliminate the bacterium, though the number of detectable endobacteria decreased significantly, resulting in partial-cured P. indica (pcPiri). pcPiri showed reduced growth in axenic cultures and poor sporulation. Consistent with this, pcPiri also showed reduced plant growth promotion and reduced systemic resistance against powdery mildew infection as compared with riPiri and lcPiri. These results are consistent with the assumption that the endobacterium R. radiobacter improves P. indica's fitness and thus contributes to the success of the tripartite Sebacinalean symbiosis.

  20. Toxicity of combined chromium(VI) and phenanthrene pollution on the seed germination, stem lengths, and fresh weights of higher plants.

    Science.gov (United States)

    Hu, Shuangqing; Gu, Hairong; Cui, Chunyan; Ji, Rong

    2016-08-01

    Studies of the interaction and toxicity of pollutant combinations such as heavy metals and PAHs are of practical importance in the remediation and monitoring of the industrial soil environment. This study investigated the single and combined toxicity of chromium(VI) and phenanthrene on three important higher plants: mung beans (Phaseolus aureus), pakchoi cabbage (Brassica chinensis), and rice (Oryza sativa). In experiments using artificial soil matrix, the EC10 and EC20 of the two pollutants, alone and in combination, were analyzed with respect to seed germination, stem length, and above-ground fresh weight of these higher plants. The additive index method was used to evaluate the combined biological toxicity of chromium(VI) and phenanthrene. The results showed that the EC20 of chromium(VI) on the stem lengths of mung beans, pakchoi cabbage, and rice was 289, 248, and 550 mg kg(-1), respectively. The corresponding EC20 values for the fresh weights of the three plants were 334, 307, and 551 mg kg(-1). The EC20 of phenanthrene on the stem lengths of mung beans, pakchoi cabbage, and rice was 528, 426, and 628 mg kg(-1), respectively. The corresponding EC20 values for the fresh weights of the three plants were 696, 585, and 768 mg kg(-1). The EC20 of a combination of chromium(VI) and phenanthrene on the stem lengths of mung beans, pakchoi cabbage, and rice was 192, 173, and 279 mg kg(-1), respectively, and 200, 205, and 271 mg kg(-1) for the fresh weights of the three plants. The single and combined exposure of soil to chromium(VI) and phenanthrene had deleterious effects on plants in the early stage of growth. Overall, pakchoi cabbage was more sensitive than mung beans and rice. The two pollutants exerted synergistic effects on the stem lengths and above-ground fresh weights of both mung beans and rice but antagonistic effects on pakchoi cabbage. The results of this study also suggested pakchoi cabbage as a sensitive indicator of soil pollution.

  1. Molecular characterization of UGT94F2 and UGT86C4, two glycosyltransferases from Picrorhiza kurrooa: comparative structural insight and evaluation of substrate recognition.

    Directory of Open Access Journals (Sweden)

    Wajid Waheed Bhat

    Full Text Available Uridine diphosphate glycosyltransferases (UGTs are pivotal in the process of glycosylation for decorating natural products with sugars. It is one of the versatile mechanisms in determining chemical complexity and diversity for the production of suite of pharmacologically active plant natural products. Picrorhiza kurrooa is a highly reputed medicinal herb known for its hepato-protective properties which are attributed to a novel group of iridoid glycosides known as picrosides. Although the plant is well studied in terms of its pharmacological properties, very little is known about the biosynthesis of these important secondary metabolites. In this study, we identified two family-1 glucosyltransferases from P. kurrooa. The full length cDNAs of UGT94F4 and UGT86C4 contained open reading frames of 1455 and 1422 nucleotides, encoding polypeptides of 484 and 473 amino acids respectively. UGT94F2 and UGT86C4 showed differential expression pattern in leaves, rhizomes and inflorescence. To elucidate whether the differential expression pattern of the two Picrorhiza UGTs correlate with transcriptional regulation via their promoters and to identify elements that could be recognized by known iridoid-specific transcription factors, upstream regions of each gene were isolated and scanned for putative cis-regulatory elements. Interestingly, the presence of cis-regulatory elements within the promoter regions of each gene correlated positively with their expression profiles in response to different phytohormones. HPLC analysis of picrosides extracted from different tissues and elicitor-treated samples showed a significant increase in picroside levels, corroborating well with the expression profile of UGT94F2 possibly indicating its implication in picroside biosynthesis. Using homology modeling and molecular docking studies, we provide an insight into the donor and acceptor specificities of both UGTs identified in this study. UGT94F2 was predicted to be an iridoid

  2. Molecular characterization of UGT94F2 and UGT86C4, two glycosyltransferases from Picrorhiza kurrooa: comparative structural insight and evaluation of substrate recognition.

    Science.gov (United States)

    Bhat, Wajid Waheed; Dhar, Niha; Razdan, Sumeer; Rana, Satiander; Mehra, Rukmankesh; Nargotra, Amit; Dhar, Rekha S; Ashraf, Nasheeman; Vishwakarma, Ram; Lattoo, Surrinder K

    2013-01-01

    Uridine diphosphate glycosyltransferases (UGTs) are pivotal in the process of glycosylation for decorating natural products with sugars. It is one of the versatile mechanisms in determining chemical complexity and diversity for the production of suite of pharmacologically active plant natural products. Picrorhiza kurrooa is a highly reputed medicinal herb known for its hepato-protective properties which are attributed to a novel group of iridoid glycosides known as picrosides. Although the plant is well studied in terms of its pharmacological properties, very little is known about the biosynthesis of these important secondary metabolites. In this study, we identified two family-1 glucosyltransferases from P. kurrooa. The full length cDNAs of UGT94F4 and UGT86C4 contained open reading frames of 1455 and 1422 nucleotides, encoding polypeptides of 484 and 473 amino acids respectively. UGT94F2 and UGT86C4 showed differential expression pattern in leaves, rhizomes and inflorescence. To elucidate whether the differential expression pattern of the two Picrorhiza UGTs correlate with transcriptional regulation via their promoters and to identify elements that could be recognized by known iridoid-specific transcription factors, upstream regions of each gene were isolated and scanned for putative cis-regulatory elements. Interestingly, the presence of cis-regulatory elements within the promoter regions of each gene correlated positively with their expression profiles in response to different phytohormones. HPLC analysis of picrosides extracted from different tissues and elicitor-treated samples showed a significant increase in picroside levels, corroborating well with the expression profile of UGT94F2 possibly indicating its implication in picroside biosynthesis. Using homology modeling and molecular docking studies, we provide an insight into the donor and acceptor specificities of both UGTs identified in this study. UGT94F2 was predicted to be an iridoid

  3. Stearoyl-acyl-carrier-protein desaturase from higher plants is structurally unrelated to the animal and fungal homologs

    Energy Technology Data Exchange (ETDEWEB)

    Shanklin, J.; Somerville, C. (Michigan State Univ., East Lansing (United States))

    1991-03-15

    Stearoyl-acyl-carrier-protein (ACP) desaturase was purified to homogeneity from avocado mesocarp, and monospecific polyclonal antibodies directed against the protein were used to isolate full-length cDNA clones from Ricinus communis (castor) seed and Cucumis sativus (cucumber). The nucleotide sequence of the castor clone pRCD1 revealed an open reading frame of 1.2 kilobases encoding a 396-amino acid protein of 45 kDa. The cucumber clone pCSD1 encoded a homologous 396-amino acid protein with 88% amino acid identity to the castor clone. Expression of pRCD1 in Saccharomyces cerevisiae resulted in the accumulation of a functional stearoyl-ACP desaturase, demonstrating that the introduction of this single gene product was sufficient to confer soluble desaturase activity to yeast. There was a 48-residue region of 29% amino acid sequence identity between residues 53 and 101 of the castor desaturase and the proximal border of the dehydratase region of the fatty acid synthase from yeast. Stearoyl-ACP mRNA was present at substantially higher levels in developing seeds than in leaf and root tissue, suggesting that expression of the {Delta}{sup 9} desaturase is developmentally regulated.

  4. Crystal Structures of Glycosyltransferase UGT78G1 Reveal the Molecular Basis for Glycosylation and Deglycosylation of (Iso)flavonoids

    Energy Technology Data Exchange (ETDEWEB)

    Modolo, Luzia V.; Li, Lenong; Pan, Haiyun; Blount, Jack W.; Dixon, Richard A.; Wang, Xiaoqiang; (SRNF)

    2010-09-21

    The glycosyltransferase UGT78G1 from Medicago truncatula catalyzes the glycosylation of various (iso)flavonoids such as the flavonols kaempferol and myricetin, the isoflavone formononetin, and the anthocyanidins pelargonidin and cyanidin. It also catalyzes a reverse reaction to remove the sugar moiety from glycosides. The structures of UGT78G1 bound with uridine diphosphate or with both uridine diphosphate and myricetin were determined at 2.1 {angstrom} resolution, revealing detailed interactions between the enzyme and substrates/products and suggesting a distinct binding mode for the acceptor/product. Comparative structural analysis and mutagenesis identify glutamate 192 as a key amino acid for the reverse reaction. This information provides a basis for enzyme engineering to manipulate substrate specificity and to design effective biocatalysts with glycosylation and/or deglycosylation activity.

  5. Glycosyltransferase cascades made fit for chemical production: Integrated biocatalytic process for the natural polyphenol C-glucoside nothofagin.

    Science.gov (United States)

    Schmölzer, Katharina; Lemmerer, Martin; Nidetzky, Bernd

    2018-03-01

    Glycosyltransferase cascades are promising tools of biocatalysis for natural product glycosylation, but their suitability for actual production remains to be shown. Here, we demonstrate at a scale of 100 g isolated product the integrated biocatalytic production of nothofagin, the natural 3'-C-β-D-glucoside of the polyphenol phloretin. A parallel reaction cascade involving coupled C-glucosyltransferase and sucrose synthase was optimized for the one-pot glucosylation of phloretin from sucrose via an UDP/UDP-glucose shuttle. Inclusion complexation with the highly water soluble 2-hydroxypropyl-β-cyclodextrin pushed the phloretin solubility to its upper practical limit (∼120 mM) and so removed the main bottleneck on an efficient synthesis of nothofagin. The biotransformation thus intensified had excellent performance metrics of 97% yield and ∼50 gproduct /L at a space-time yield of 3 g/L/hr. The UDP-glucose was regenerated up to ∼220 times. A scalable downstream process for efficient recovery of nothofagin (≥95% purity; ≥65% yield) was developed. A tailored anion-exchange chromatography at pH 8.5 was used for capture and initial purification of the product. Recycling of the 2-hydroxypropyl-β-cyclodextrin would also be possible at this step. Product precipitation at a lowered pH of 6.0 and re-dissolution in acetone effectively replaced desalting by size exclusion chromatography in the final step of nothofagin purification. This study therefore, reveals the potential for process intensification in the glycosylation of polyphenol acceptors by glycosyltransferase cascades. It demonstrates that, with up- and downstream processing carefully optimized and suitably interconnected, a powerful biocatalytic technology becomes available for the production of an important class of glycosides difficult to prepare otherwise. © 2017 Wiley Periodicals, Inc.

  6. Overexpression of Brucella putative glycosyltransferase WbkA in B. abortus RB51 leads to production of exopolysaccharide

    Directory of Open Access Journals (Sweden)

    Neha eDabral

    2015-06-01

    Full Text Available Brucella spp. are Gram-negative, facultative intracellular bacteria that cause brucellosis in mammals. Brucella strains containing the O-polysaccharide in their cell wall structure exhibit a smooth phenotype whereas the strains devoid of the polysaccharide show rough phenotype. B. abortus strain RB51 is a stable rough attenuated mutant which is used as a licensed live vaccine for bovine brucellosis. Previous studies have shown that the wboA gene, which encodes a glycosyltransferase required for the synthesis of O-polysaccharide, is disrupted in B. abortus RB51 by an IS711 element. Although complementation of strain RB51 with a functional wboA gene results in O-polysaccharide synthesis in the cytoplasm, it does not result in smooth phenotype. The aim of this study was to determine if overexpression of Brucella WbkA or WbkE, two additional putative glycosyltransferases essential for O-polysaccharide synthesis, in strain RB51 would result in the O-polysaccharide synthesis and smooth phenotype. Our results demonstrate that overexpression of wbkA or wbkE gene in RB51 does not result in O-polysaccharide expression as shown by Western blotting with specific antibodies. However, wbkA, but not wbkE, overexpression leads to the development of a clumping phenotype and the production of exopolysaccharide(s containing mannose, galactose, N-acetylglucosamine and N-acetylgalactosamine. Moreover, we found that the clumping recombinant strain displays increased adhesion to polystyrene plates. The recombinant strain was similar to strain RB51 in its attenuation characteristic and in its ability to induce protective immunity against virulent B. abortus challenge in mice.

  7. Overexpression of Brucella putative glycosyltransferase WbkA in B. abortus RB51 leads to production of exopolysaccharide.

    Science.gov (United States)

    Dabral, Neha; Jain-Gupta, Neeta; Seleem, Mohamed N; Sriranganathan, Nammalwar; Vemulapalli, Ramesh

    2015-01-01

    Brucella spp. are Gram-negative, facultative intracellular bacteria that cause brucellosis in mammals. Brucella strains containing the O-polysaccharide in their cell wall structure exhibit a smooth phenotype whereas the strains devoid of the polysaccharide show rough phenotype. B. abortus strain RB51 is a stable rough attenuated mutant which is used as a licensed live vaccine for bovine brucellosis. Previous studies have shown that the wboA gene, which encodes a glycosyltransferase required for the synthesis of O-polysaccharide, is disrupted in B. abortus RB51 by an IS711 element. Although complementation of strain RB51 with a functional wboA gene results in O-polysaccharide synthesis in the cytoplasm, it does not result in smooth phenotype. The aim of this study was to determine if overexpression of Brucella WbkA or WbkE, two additional putative glycosyltransferases essential for O-polysaccharide synthesis, in strain RB51 would result in the O-polysaccharide synthesis and smooth phenotype. Our results demonstrate that overexpression of wbkA or wbkE gene in RB51 does not result in O-polysaccharide expression as shown by Western blotting with specific antibodies. However, wbkA, but not wbkE, overexpression leads to the development of a clumping phenotype and the production of exopolysaccharide(s) containing mannose, galactose, N-acetylglucosamine, and N-acetylgalactosamine. Moreover, we found that the clumping recombinant strain displays increased adhesion to polystyrene plates. The recombinant strain was similar to strain RB51 in its attenuation characteristic and in its ability to induce protective immunity against virulent B. abortus challenge in mice.

  8. Computational insights into active site shaping for substrate specificity and reaction regioselectivity in the EXTL2 retaining glycosyltransferase.

    Science.gov (United States)

    Mendoza, Fernanda; Lluch, José M; Masgrau, Laura

    2017-11-07

    Glycosyltransferases are enzymes that catalyze a monosaccharide transfer reaction from a donor to an acceptor substrate with the synthesis of a new glycosidic bond. They are highly substrate specific and regioselective, even though the acceptor substrate often presents multiple reactive groups. Currently, many efforts are dedicated to the development of biocatalysts for glycan synthesis and, therefore, a better understanding of how natural enzymes achieve this goal can be of valuable help. To gain a deeper insight into the catalytic strategies used by retaining glycosyltransferases, the wild type EXTL2 (CAZy family GT64) and four mutant forms (at positions 293 and 246) were studied using QM(DFT)/MM calculations and molecular dynamics simulations. Existing hypotheses on the roles of Arg293, an enigmatic residue in the CAZy family GT64 that seemed to contradict a mechanism through an oxocarbenium intermediate, and of Asp246 have been tested. We also provide a molecular interpretation for the results of site-directed mutagenesis experiments. Moreover, we have investigated why an Asp, and not a Glu like in the family GT6, is found on the β-face of the transferred GlcNAc. It is predicted that an Asp246Glu mutant of EXTL2 would be unable to catalyze the α-1,4 transfer. The results herein presented clarify the roles that Arg293, Asp246 and Leu213 have at different stages of the catalytic process (for binding but also for efficient chemical reaction). Altogether, we provide a molecular view that connects the identity and conformation of these residues to the substrate specificity and regioselectivity of the enzyme, illustrating a delicate interplay between all these aspects.

  9. UV Screening in Native and Non-native Plant Species in the Tropical Alpine: Implications for Climate Change-Driven Migration of Species to Higher Elevations.

    Science.gov (United States)

    Barnes, Paul W; Ryel, Ronald J; Flint, Stephan D

    2017-01-01

    Ongoing changes in Earth's climate are shifting the elevation ranges of many plant species with non-native species often experiencing greater expansion into higher elevations than native species. These climate change-induced shifts in distributions inevitably expose plants to novel biotic and abiotic environments, including altered solar ultraviolet (UV)-B (280-315 nm) radiation regimes. Do the greater migration potentials of non-native species into higher elevations imply that they have more effective UV-protective mechanisms than native species? In this study, we surveyed leaf epidermal UV-A transmittance (TUV A) in a diversity of plant species representing different growth forms to test whether native and non-native species growing above 2800 m elevation on Mauna Kea, Hawaii differed in their UV screening capabilities. We further compared the degree to which TUV A varied along an elevation gradient in the native shrub Vaccinium reticulatum and the introduced forb Verbascum thapsus to evaluate whether these species differed in their abilities to adjust their levels of UV screening in response to elevation changes in UV-B. For plants growing in the Mauna Kea alpine/upper subalpine, we found that adaxial TUV A, measured with a UVA-PAM fluorometer, varied significantly among species but did not differ between native (mean = 6.0%; n = 8) and non-native (mean = 5.8%; n = 11) species. When data were pooled across native and non-native taxa, we also found no significant effect of growth form on TUV A, though woody plants (shrubs and trees) were represented solely by native species whereas herbaceous growth forms (grasses and forbs) were dominated by non-native species. Along an elevation gradient spanning 2600-3800 m, TUV A was variable (mean range = 6.0-11.2%) and strongly correlated with elevation and relative biologically effective UV-B in the exotic V. thapsus; however, TUV A was consistently low (3%) and did not vary with elevation in the native V. reticulatum

  10. Can Stress-Induced Biochemical Differences drive Variation in the Hydrogen Isotope Composition of Leaf Wax n-Alkanes from Terrestrial Higher Plants?

    Science.gov (United States)

    Eley, Y.; Pedentchouk, N.; Dawson, L.

    2014-12-01

    Recent research has identified that interspecies variation in leaf wax n-alkane 2H/1H from plants growing at the same geographical location can exceed 100‰. These differences cannot easily be explained by mechanisms that influence the isotopic composition of leaf water. Biochemical processes are therefore likely to drive some of this variability. Currently, however, little is known about the relative importance of different biochemical processes in shaping n-alkane hydrogen isotope composition. To explore this issue, we combined n-alkane δ2H analysis with measurements of: (i) the percentage content of leaf C and N; and (ii) foliar δ15N, from seven plants growing at Stiffkey salt marsh, Norfolk, UK. These species differ biochemically in respect of the protective compounds they produce under salt or water stressed conditions, with monocots generally producing more carbohydrates, and dicots producing more nitrogenous compounds. We found that monocots had higher %C, while dicots had higher %N and 15N-enriched leaf tissue. We identified a systematic relationship between the nature of the dominant protective compound produced (carbohydrate vs. nitrogenous) and n-alkane 2H/1H: species with a greater proportion of carbohydrates have more negative δ2H values. These findings might imply that shifts in the relative contribution of H to pyruvate from NADPH (2H-depleted) and recycled carbohydrates (2H-enriched) can influence n-alkane δ2H. The 2H-depletion of monocot n-alkanes relative to dicots may therefore be due to a greater proportion of NADPH-derived H incorporated into pyruvate because of their enhanced demand for carbohydrates. The production of protective compounds in plant species is a common response to a range of abiotic stresses (e.g. high UV irradiation, drought, salinity, high/low temperature). Species-specific biochemical responses to stress could therefore influence n-alkane 2H/1H across a range of habitats. This study highlights the importance of detailed

  11. Small high-yielding binary Ti vectors pLSU with co-directional replicons for Agrobacterium tumefaciens-mediated transformation of higher plants.

    Science.gov (United States)

    Lee, Seokhyun; Su, Guiying; Lasserre, Eric; Aghazadeh, Monty Arta; Murai, Norimoto

    2012-05-01

    Small high-yielding binary Ti vectors of Agrobacterium tumefaciens were constructed to increase the cloning efficiency and plasmid yield in Escherichia coli and A. tumefaciens for transformation of higher plants. We reduced the size of the binary vector backbone to 4566bp with ColE1 replicon (715bp) for E. coli and VS1 replicon (2654bp) for A. tumefaciens, a bacterial kanamycin resistance gene (999bp), and the T-DNA region (152bp). The binary Ti vectors with the truncated VS1 replicon were stably maintained with more than 98% efficiency in A. tumefaciens without antibiotic selection for 4 days of successive transfers. The transcriptional direction of VS1 replicon can be the same as that of ColE1 replicon (co-directional transcription), or opposite (head-on transcription) as in the case of widely used vectors (pPZP or pCambia). New binary vectors with co-directional transcription yielded in E. coli up to four-fold higher transformation frequency than those with the head-on transcription. In A. tumefaciens the effect of co-directional transcription is still positive in up to 1.8-fold higher transformation frequency than that of head-on transcription. Transformation frequencies of new vectors are over six-fold higher than those of pCambia vector in A. tumefaciens. DNA yields of new vectors were three to five-fold greater than pCambia in E. coli. The proper functions of the new T-DNA borders and new plant selection marker genes were confirmed after A. tumefaciens-mediated transformation of tobacco leaf discs, resulting in virtually all treated leaf discs transformed and induced calli. Genetic analysis of kanamycin resistance trait among the progeny showed that the kanamycin resistance and sensitivity traits were segregated into the 3:1 ratio, indicating that the kanamycin resistance genes were integrated stably into a locus or closely linked loci of the nuclear chromosomal DNA of the primary transgenic tobacco plants and inherited to the second generation. © 2012

  12. Plant cell wall glycosyltransferases: High-throughput recombinant expression screening and general requirements for these challenging enzymes

    DEFF Research Database (Denmark)

    Welner, Ditte Hededam; Shin, David; Tomaleri, Giovani P.

    2017-01-01

    knowledge of the enzyme(s) being studied. We have developed a rational approach to this process. We devise a pipeline comprising in silico selection of targets and construct design, and high-throughput expression screening, target enrichment, and hit identification. We have applied this pipeline to a test...

  13. Regulation of plant cells, cell walls and development by mechanical signals

    Energy Technology Data Exchange (ETDEWEB)

    Meyerowitz, Elliot M. [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2016-06-14

    The overall goal of the revised scope of work for the final year of funding was to characterize cell wall biosynthesis in developing cotyledons and in the shoot apical meristem of Arabidopsis thaliana, as a way of learning about developmental control of cell wall biosynthesis in plants, and interactions between cell wall biosynthesis and the microtubule cytoskeleton. The proposed work had two parts – to look at the effect of mutation in the SPIRAL2 gene on microtubule organization and reorganization, and to thoroughly characterize the glycosyltransferase genes expressed in shoot apical meristems by RNA-seq experiments, by in situ hybridization of the RNAs expressed in the meristem, and by antibody staining of the products of the glycosyltransferases in meristems. Both parts were completed; the spiral2 mutant was found to speed microtubule reorientation after ablation of adjacent cells, supporting our hypothesis that reorganization correlates with microtubule severing, the rate of which is increased by the mutation. The glycosyltransferase characterization was completed and published as Yang et al. (2016). Among the new things learned was that primary cell wall biosynthesis is strongly controlled both by cell type, and by stage of cell cycle, implying not only that different, even adjacent, cells can have different sugar linkages in their (nonshared) walls, but also that a surprisingly large proportion of glycosyltransferases is regulated in the cell cycle, and therefore that the cell cycle regulates wall maturation to a degree previously unrecognized.

  14. Expression, purification, crystallization and preliminary X-ray characterization of a putative glycosyltransferase of the GT-A fold found in mycobacteria

    Energy Technology Data Exchange (ETDEWEB)

    Fulton, Zara; Crellin, Paul K.; Brammananth, Rajini; Zaker-Tabrizi, Leyla; Coppel, Ross L.; Rossjohna, Jamie; Beddoe, Travis (Monash)

    2008-05-28

    Glycosidic bond formation is a ubiquitous enzyme-catalysed reaction. This glycosyltransferase-mediated process is responsible for the biosynthesis of innumerable oligosaccharides and glycoconjugates and is often organism- or cell-specific. However, despite the abundance of genomic information on glycosyltransferases (GTs), there is a lack of structural data for this versatile class of enzymes. Here, the cloning, expression, purification and crystallization of an essential 329-amino-acid (34.8 kDa) putative GT of the classic GT-A fold implicated in mycobacterial cell-wall biosynthesis are reported. Crystals of MAP2569c from Mycobacterium avium subsp. paratuberculosis were grown in 1.6 M monoammonium dihydrogen phosphate and 0.1 M sodium citrate pH 5.5. A complete data set was collected to 1.8 {angstrom} resolution using synchrotron radiation from a crystal belonging to space group P4{sub 1}2{sub 1}2.

  15. Expression, purification, crystallization and preliminary X-ray characterization of a putative glycosyltransferase of the GT-A fold found in mycobacteria

    Energy Technology Data Exchange (ETDEWEB)

    Fulton, Zara [The Protein Crystallography Unit, Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800 (Australia); Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800 (Australia); Crellin, Paul K.; Brammananth, Rajini [Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800 (Australia); Department of Microbiology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800 (Australia); Zaker-Tabrizi, Leyla [The Protein Crystallography Unit, Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800 (Australia); Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800 (Australia); Coppel, Ross L. [Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800 (Australia); Department of Microbiology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800 (Australia); Rossjohn, Jamie, E-mail: jamie.rossjohn@med.monash.edu.au; Beddoe, Travis, E-mail: jamie.rossjohn@med.monash.edu.au [The Protein Crystallography Unit, Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800 (Australia); Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800 (Australia)

    2008-05-01

    MAP2569c from M. avium subsp. paratuberculosis, a putative glycosyltransferase implicated in mycobacterial cell-wall biosynthesis, was cloned, expressed, purified and crystallized. X-ray diffraction data were collected to 1.8 Å resolution. Glycosidic bond formation is a ubiquitous enzyme-catalysed reaction. This glycosyltransferase-mediated process is responsible for the biosynthesis of innumerable oligosaccharides and glycoconjugates and is often organism- or cell-specific. However, despite the abundance of genomic information on glycosyltransferases (GTs), there is a lack of structural data for this versatile class of enzymes. Here, the cloning, expression, purification and crystallization of an essential 329-amino-acid (34.8 kDa) putative GT of the classic GT-A fold implicated in mycobacterial cell-wall biosynthesis are reported. Crystals of MAP2569c from Mycobacterium avium subsp. paratuberculosis were grown in 1.6 M monoammonium dihydrogen phosphate and 0.1 M sodium citrate pH 5.5. A complete data set was collected to 1.8 Å resolution using synchrotron radiation from a crystal belonging to space group P4{sub 1}2{sub 1}2.

  16. Novel staphylococcal glycosyltransferases SdgA and SdgB mediate immunogenicity and protection of virulence-associated cell wall proteins.

    Directory of Open Access Journals (Sweden)

    Wouter L W Hazenbos

    Full Text Available Infection of host tissues by Staphylococcus aureus and S. epidermidis requires an unusual family of staphylococcal adhesive proteins that contain long stretches of serine-aspartate dipeptide-repeats (SDR. The prototype member of this family is clumping factor A (ClfA, a key virulence factor that mediates adhesion to host tissues by binding to extracellular matrix proteins such as fibrinogen. However, the biological siginificance of the SDR-domain and its implication for pathogenesis remain poorly understood. Here, we identified two novel bacterial glycosyltransferases, SdgA and SdgB, which modify all SDR-proteins in these two bacterial species. Genetic and biochemical data demonstrated that these two glycosyltransferases directly bind and covalently link N-acetylglucosamine (GlcNAc moieties to the SDR-domain in a step-wise manner, with SdgB appending the sugar residues proximal to the target Ser-Asp repeats, followed by additional modification by SdgA. GlcNAc-modification of SDR-proteins by SdgB creates an immunodominant epitope for highly opsonic human antibodies, which represent up to 1% of total human IgG. Deletion of these glycosyltransferases renders SDR-proteins vulnerable to proteolysis by human neutrophil-derived cathepsin G. Thus, SdgA and SdgB glycosylate staphylococcal SDR-proteins, which protects them against host proteolytic activity, and yet generates major eptopes for the human anti-staphylococcal antibody response, which may represent an ongoing competition between host and pathogen.

  17. Base substitution mutations in uridinediphosphate-dependent glycosyltransferase 76G1 gene of Stevia rebaudiana causes the low levels of rebaudioside A: mutations in UGT76G1, a key gene of steviol glycosides synthesis.

    Science.gov (United States)

    Yang, Yong-Heng; Huang, Su-Zhen; Han, Yu-Lin; Yuan, Hai-Yan; Gu, Chun-Sun; Zhao, Yan-Hai

    2014-07-01

    Steviol glycosides, extracted from the leaves of Stevia rebaudiana (Bert) Bertoni, are calorie-free sugar substitute of natural origin with intensely sweet (Boileau et al., 2012). Stevioside and rebaudioside A are the two main kinds of the diterpenic glycosides. We analyzed the concentration of stevioside and rebaudioside A in Stevia leaves of about 500 samples (hybrid progenies) and discovered a mutation plant "Z05" with very low levels of rebaudioside A. Because UGT76G1, a uridinediphosphate-dependent glycosyltransferases, is responsible for the conversion from stevioside to rebaudioside A (Richman et al., 2005), so mutation identification was done by sequencing the candidate gene, UGT76G1. In this study molecular analysis of two strains revealed a heterozygotic nonsense mutation of c.389T > G (p.L121X) in UGT76G1. Meanwhile, we found some amino acid substitutions significant change the protein structure. And the difference of enzyme activity between two strains proved the lack of functionality of UGT76G1 of the mutation "Z05". So the nonsense mutation and amino acid substitution mutation resulted in the low levels of rebaudioside A. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. Firmly Planted, Always Moving.

    Science.gov (United States)

    Raikhel, Natasha V

    2017-04-28

    I was a budding pianist immersed in music in Leningrad, in the Soviet Union (now Saint Petersburg, Russia), when I started over, giving up sheet music for the study of ciliates. In a second starting-over story, I emigrated to the United States, where I switched to studying carbohydrate-binding plant lectin proteins, dissecting plant vesicular trafficking, and isolating novel glycosyltransferases responsible for making cell wall polysaccharides. I track my journey as a plant biologist from student to principal investigator to founding director of the Center for Plant Cell Biology and then director of the Institute for Integrative Genome Biology at the University of California, Riverside. I discuss implementing a new vision as the first and (so far) only female editor in chief of Plant Physiology, as well as how my laboratory helped develop chemical genomics tools to study the functions of essential plant proteins. Always wanting to give back what I received, I discuss my present efforts to develop female scientist leadership in Chinese universities and a constant theme throughout my life: a love of art and travel.

  19. Representation of pheromones, interspecific signals, and plant odors in higher olfactory centers; mapping physiologically identified antennal-lobe projection neurons in the male heliothine moth

    Directory of Open Access Journals (Sweden)

    Xin-Cheng eZhao

    2014-10-01

    Full Text Available In the primary olfactory centre of the moth brain, for example, a few enlarged glomeruli situated dorsally, at the entrance of the antennal nerve, are devoted to information about female-produced substances whereas a set of more numerous ordinary glomeruli receives input about general odorants. Heliothine moths are particularly suitable for studying central chemosensory mechanisms not only because of their anatomically separated systems for plant odours and pheromones but also due to their use of female-produced substances in communication across the species. Thus, the male-specific system of heliothine moths includes two sub arrangements, one ensuring attraction and mating behavior by carrying information about pheromones released by conspecifics, and the other reproductive isolation via signal information emitted from heterospecifics. Based on previous tracing experiments, a general chemotopic organization of the male-specific glomeruli has been demonstrated in a number of heliothine species. As compared to the well explored organization of the moth antennal lobe, demonstrating a non-overlapping representation of the biologically relevant stimuli, less is known about the neural arrangement residing at the following synaptic level, i.e. the mushroom body calyces and the lateral horn. In the study presented here, we have labelled physiologically characterized antennal-lobe projection neurons in males of the two heliothine species, Heliothis virescens and Helicoverpa assulta, for the purpose of mapping their target regions in the protocerebrum. In order to compare the representation of plant odours, pheromones, and interspecific signals in the higher brain regions of each species, we have created standard brain atlases and registered three-dimensional models of distinct uniglomerular projection neuron types into the relevant atlas.

  20. Structure and Mechanism of Staphylococcus aureus TarS, the Wall Teichoic Acid β-glycosyltransferase Involved in Methicillin Resistance.

    Directory of Open Access Journals (Sweden)

    Solmaz Sobhanifar

    2016-12-01

    Full Text Available In recent years, there has been a growing interest in teichoic acids as targets for antibiotic drug design against major clinical pathogens such as Staphylococcus aureus, reflecting the disquieting increase in antibiotic resistance and the historical success of bacterial cell wall components as drug targets. It is now becoming clear that β-O-GlcNAcylation of S. aureus wall teichoic acids plays a major role in both pathogenicity and antibiotic resistance. Here we present the first structure of S. aureus TarS, the enzyme responsible for polyribitol phosphate β-O-GlcNAcylation. Using a divide and conquer strategy, we obtained crystal structures of various TarS constructs, mapping high resolution overlapping N-terminal and C-terminal structures onto a lower resolution full-length structure that resulted in a high resolution view of the entire enzyme. Using the N-terminal structure that encapsulates the catalytic domain, we furthermore captured several snapshots of TarS, including the native structure, the UDP-GlcNAc donor complex, and the UDP product complex. These structures along with structure-guided mutants allowed us to elucidate various catalytic features and identify key active site residues and catalytic loop rearrangements that provide a valuable platform for anti-MRSA drug design. We furthermore observed for the first time the presence of a trimerization domain composed of stacked carbohydrate binding modules, commonly observed in starch active enzymes, but adapted here for a poly sugar-phosphate glycosyltransferase.

  1. Identification of a Fragment-Based Scaffold that Inhibits the Glycosyltransferase WaaG from Escherichia coli

    Directory of Open Access Journals (Sweden)

    Claudio Muheim

    2016-01-01

    Full Text Available WaaG is a glycosyltransferase that is involved in the biosynthesis of lipopolysaccharide in Gram-negative bacteria. Inhibitors of WaaG are highly sought after as they could be used to inhibit the biosynthesis of the core region of lipopolysaccharide, which would improve the uptake of antibiotics. Herein, we establish an activity assay for WaaG using 14C-labeled UDP-glucose and LPS purified from a ∆waaG strain of Escherichia coli. We noted that addition of the lipids phosphatidylglycerol (PG and cardiolipin (CL, as well as the detergent 3-[(3-cholamidopropyldimethylammonio]-1-propanesulfonate (CHAPS increased activity. We then use the assay to determine if three molecular scaffolds, which bind to WaaG, could inhibit its activity in vitro. We show that 4-(2-amino-1,3-thiazol-4-ylphenol inhibits WaaG (IC50 1.0 mM, but that the other scaffolds do not. This study represents an important step towards an inhibitor of WaaG by fragment-based lead discovery.

  2. Engineered jadomycin analogues with altered sugar moieties revealing JadS as a substrate flexible O-glycosyltransferase.

    Science.gov (United States)

    Li, Liyuan; Pan, Guohui; Zhu, Xifen; Fan, Keqiang; Gao, Wubin; Ai, Guomin; Ren, Jinwei; Shi, Mingxin; Olano, Carlos; Salas, José A; Yang, Keqian

    2017-07-01

    Glycosyltransferases (GTs)-mediated glycodiversification studies have drawn significant attention recently, with the goal of generating bioactive compounds with improved pharmacological properties by diversifying the appended sugars. The key to achieving glycodiversification is to identify natural and/or engineered flexible GTs capable of acting upon a broad range of substrates. Here, we report the use of a combinatorial biosynthetic approach to probe the substrate flexibility of JadS, the GT in jadomycin biosynthesis, towards different non-native NDP-sugar substrates, enabling us to identify six jadomycin B analogues with different sugar moieties. Further structural engineering by precursor-directed biosynthesis allowed us to obtain 11 new jadomycin analogues. Our results for the first time show that JadS is a flexible O-GT that can utilize both L- and D- sugars as donor substrates, and tolerate structural changes at the C2, C4 and C6 positions of the sugar moiety. JadS may be further exploited to generate novel glycosylated jadomycin molecules in future glycodiversification studies.

  3. Two Glycosyltransferase Genes of Haemophilus parasuis SC096 Implicated in Lipo-oligosaccharide Biosynthesis, Serum Resistance, Adherence and Invasion

    Directory of Open Access Journals (Sweden)

    Qi Zhou

    2016-09-01

    Full Text Available Haemophilus parasuis is a common opportunistic pathogen known for its ability to colonize healthy piglets and causes Glässer’s disease. The lipooligosaccharide (LOS of H. parasuis is a potential virulence-associated factor. In this study, two putative glycosyltransferases that might be involved in LOS synthesis in H. parasuis SC096 were identified (lgtB and lex-1. Mutants were constructed to investigate the roles of the lgtB and lex-1 genes. The LOS from the ΔlgtB or Δlex-1 mutant showed truncated structure on silver-stained SDS-PAGE gel compared to the wild-type strain. The ΔlgtB and Δlex-1 mutants were significantly more sensitive to 50% porcine serum, displaying 15.0% and 54.46% survival rates, respectively. Complementation of the lex-1 mutant restored the serum-resistant phenotype. Additionally, the ΔlgtB and Δlex-1 strains showed impaired ability to adhere to and invade porcine kidney epithelial cells (PK-15. The above results suggested that the lgtB and lex-1 genes of the H. parasuis SC096 strain participated in LOS synthesis and were involved in serum resistance, adhesion and invasion.

  4. In Vitro Assessment of Extracts of the Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Higher Basidiomycetes) Against Different Plant Pathogenic Fungi.

    Science.gov (United States)

    Baig, Mirza Nabeel; Shahid, Ahmad Ali; Ali, Muhammad

    2015-01-01

    Five isolates of the lingzhi or reishi medicinal mushroom Ganoderma lucidum (GL-1, GL-2, GL-3, GL-4, GL-5) were collected from different locations within and surrounding Lahore, Pakistan, to study the antifungal potential of their bioactive compounds. After studying morphology, different concentrations of the extracts were prepared in methanol and water using a Soxhlet extractor. Different cultures of fungal pathogens were acquired from the First Fungal Culture Bank of Pakistan, University of the Punjab, Lahore. The antimicrobial potential of 5 G. lucidum samples against 5 fungal pathogens (Fusarium oxysporum, Aspergillus niger, A. flavus, Penicillium sp., and Alternaria alternata) was observed. The lowest biomass reduction (7%) was observed in 1% and 2% concentrations of a methanolic extract and 6% in the case of a water extract. Major inhibition was observed using higher concentrations of the methanolic extract (3% and 4%). These extracts significantly suppressed fungal biomass up to 38% and 56% in A. niger, 47% in A. flavus, 58% in ,i>Penicillium sp., 46% in A. alternaria, and 45% in F. oxysporum compared with the control. It was concluded from these studies that methanolic extracts of G. lucidum showed better activity against all plant fungal pathogens when compared with the water extracts.

  5. LC-MS/MS versus TLC plus GC methods: Consistency of glycerolipid and fatty acid profiles in microalgae and higher plant cells and effect of a nitrogen starvation.

    Science.gov (United States)

    Jouhet, Juliette; Lupette, Josselin; Clerc, Olivier; Magneschi, Leonardo; Bedhomme, Mariette; Collin, Séverine; Roy, Sylvaine; Maréchal, Eric; Rébeillé, Fabrice

    2017-01-01

    Methods to analyze lipidomes have considerably evolved, more and more based on mass spectrometry technics (LC-MS/MS). However, accurate quantifications using these methods require 13C-labeled standards for each lipid, which is not feasible because of the very large number of molecules. Thus, quantifications rely on standard molecules representative of a whole class of lipids, which might lead to false estimations of some molecular species. Here, we determined and compared glycerolipid distributions from three different types of cells, two microalgae (Phaeodactylum tricornutum, Nannochloropsis gaditana) and one higher plant (Arabidopsis thaliana), using either LC-MS/MS or Thin Layer Chromatography coupled with Gas Chromatography (TLC-GC), this last approach relying on the precise quantification of the fatty acids present in each glycerolipid class. Our results showed that the glycerolipid distribution was significantly different depending on the method used. How can one reconcile these two analytical methods? Here we propose that the possible bias with MS data can be circumvented by systematically running in tandem with the sample to be analyzed a lipid extract from a qualified control (QC) of each type of cells, previously analyzed by TLC-GC, and used as an external standard to quantify the MS results. As a case study, we applied this method to compare the impact of a nitrogen deficiency on the three types of cells.

  6. Older leaves of lettuce (Lactuca spp.) support higher levels of Salmonella enterica ser. Senftenberg attachment and show greater variation between plant accessions than do younger leaves.

    Science.gov (United States)

    Hunter, Paul J; Shaw, Robert K; Berger, Cedric N; Frankel, Gad; Pink, David; Hand, Paul

    2015-06-01

    Salmonella can bind to the leaves of salad crops including lettuce and survive for commercially relevant periods. Previous studies have shown that younger leaves are more susceptible to colonization than older leaves and that colonization levels are dependent on both the bacterial serovar and the lettuce cultivar. In this study, we investigated the ability of two Lactuca sativa cultivars (Saladin and Iceberg) and an accession of wild lettuce (L. serriola) to support attachment of Salmonella enterica serovar Senftenberg, to the first and fifth to sixth true leaves and the associations between cultivar-dependent variation in plant leaf surface characteristics and bacterial attachment. Attachment levels were higher on older leaves than on the younger ones and these differences were associated with leaf vein and stomatal densities, leaf surface hydrophobicity and leaf surface soluble protein concentrations. Vein density and leaf surface hydrophobicity were also associated with cultivar-specific differences in Salmonella attachment, although the latter was only observed in the older leaves and was also associated with level of epicuticular wax. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. LC-MS/MS versus TLC plus GC methods: Consistency of glycerolipid and fatty acid profiles in microalgae and higher plant cells and effect of a nitrogen starvation

    Science.gov (United States)

    Jouhet, Juliette; Lupette, Josselin; Clerc, Olivier; Magneschi, Leonardo; Bedhomme, Mariette; Collin, Séverine; Roy, Sylvaine; Maréchal, Eric

    2017-01-01

    Methods to analyze lipidomes have considerably evolved, more and more based on mass spectrometry technics (LC-MS/MS). However, accurate quantifications using these methods require 13C-labeled standards for each lipid, which is not feasible because of the very large number of molecules. Thus, quantifications rely on standard molecules representative of a whole class of lipids, which might lead to false estimations of some molecular species. Here, we determined and compared glycerolipid distributions from three different types of cells, two microalgae (Phaeodactylum tricornutum, Nannochloropsis gaditana) and one higher plant (Arabidopsis thaliana), using either LC-MS/MS or Thin Layer Chromatography coupled with Gas Chromatography (TLC-GC), this last approach relying on the precise quantification of the fatty acids present in each glycerolipid class. Our results showed that the glycerolipid distribution was significantly different depending on the method used. How can one reconcile these two analytical methods? Here we propose that the possible bias with MS data can be circumvented by systematically running in tandem with the sample to be analyzed a lipid extract from a qualified control (QC) of each type of cells, previously analyzed by TLC-GC, and used as an external standard to quantify the MS results. As a case study, we applied this method to compare the impact of a nitrogen deficiency on the three types of cells. PMID:28771624

  8. LC-MS/MS versus TLC plus GC methods: Consistency of glycerolipid and fatty acid profiles in microalgae and higher plant cells and effect of a nitrogen starvation.

    Directory of Open Access Journals (Sweden)

    Juliette Jouhet

    Full Text Available Methods to analyze lipidomes have considerably evolved, more and more based on mass spectrometry technics (LC-MS/MS. However, accurate quantifications using these methods require 13C-labeled standards for each lipid, which is not feasible because of the very large number of molecules. Thus, quantifications rely on standard molecules representative of a whole class of lipids, which might lead to false estimations of some molecular species. Here, we determined and compared glycerolipid distributions from three different types of cells, two microalgae (Phaeodactylum tricornutum, Nannochloropsis gaditana and one higher plant (Arabidopsis thaliana, using either LC-MS/MS or Thin Layer Chromatography coupled with Gas Chromatography (TLC-GC, this last approach relying on the precise quantification of the fatty acids present in each glycerolipid class. Our results showed that the glycerolipid distribution was significantly different depending on the method used. How can one reconcile these two analytical methods? Here we propose that the possible bias with MS data can be circumvented by systematically running in tandem with the sample to be analyzed a lipid extract from a qualified control (QC of each type of cells, previously analyzed by TLC-GC, and used as an external standard to quantify the MS results. As a case study, we applied this method to compare the impact of a nitrogen deficiency on the three types of cells.

  9. Expression of recombinant vaccines and antibodies in plants.

    Science.gov (United States)

    Ko, Kisung

    2014-06-01

    Plants are able to perform post-translational maturations of therapeutic proteins required for their functional biological activity and suitable in vivo pharmacokinetics. Plants can be a low-cost, large-scale production platform of recombinant biopharmaceutical proteins such as vaccines and antibodies. Plants, however, lack mechanisms of processing authentic human N-glycosylation, which imposes a major limitation in their use as an expression system for therapeutic glycoproducts. Efforts have been made to circumvent plant-specific N-glycosylation, as well as to supplement the plant's endogenous system with human glycosyltransferases for non-immunogenic and humanized N-glycan production. Herein we review studies on the potential of plants to serve as production systems for therapeutic and prophylactic biopharmaceuticals. We have especially focused on recombinant vaccines and antibodies and new expression strategies to overcome the existing problems associated with their production in plants.

  10. The WaaL O-antigen lipopolysaccharide ligase has features in common with metal ion-independent inverting glycosyltransferases.

    Science.gov (United States)

    Ruan, Xiang; Loyola, David E; Marolda, Cristina L; Perez-Donoso, José M; Valvano, Miguel A

    2012-02-01

    WaaL is a membrane enzyme that catalyzes a key step in lipopolysaccharide (LPS) synthesis: the glycosidic bonding of a sugar at the proximal end of the undecaprenyl-diphosphate (Und-PP) O-antigen with a terminal sugar of the lipid A-core oligosaccharide (OS). Utilizing an in vitro assay, we demonstrate here that ligation with purified Escherichia coli WaaL occurs without adenosine-5'-triphosphate (ATP) and magnesium ions. Furthermore, E. coli and Pseudomonas aeruginosa WaaL proteins cannot catalyze ATP hydrolysis in vitro. We also show that a lysine substitution of the arginine (Arg)-215 residue renders an active protein, whereas WaaL mutants with alanine replacements in the periplasmic-exposed residues Arg-215, Arg-288 and histidine (His)-338 and also the membrane-embedded aspartic acid-389 are nonfunctional. An in silico approach, combining predicted topological information with the analysis of sequence conservation, confirms the importance of a positive charge at the small periplasmic loop of WaaL, since an Arg corresponding to Arg-215 was found at a similar position in all the WaaL homologs. Also, a universally conserved H[NSQ]X(9)GXX[GTY] motif spanning the C-terminal end of the predicted large periplasmic loop and the membrane boundary of the transmembrane helix was identified. The His residue in this motif corresponds to His-338. A survey of LPS structures in which the linkage between O-antigen and lipid A-core OS was elucidated reveals that it is always in the β-configuration, whereas the sugars bound to Und-PP are in the α-configuration. Together, our biochemical and in silico data argue that WaaL proteins use a common reaction mechanism and share features of metal ion-independent inverting glycosyltransferases.

  11. Multiple Roles for Enterococcus faecalis Glycosyltransferases in Biofilm-Associated Antibiotic Resistance, Cell Envelope Integrity, and Conjugative Transfer

    Science.gov (United States)

    Dale, Jennifer L.; Cagnazzo, Julian; Phan, Chi Q.; Barnes, Aaron M. T.

    2015-01-01

    The emergence of multidrug-resistant bacteria and the limited availability of new antibiotics are of increasing clinical concern. A compounding factor is the ability of microorganisms to form biofilms (communities of cells encased in a protective extracellular matrix) that are intrinsically resistant to antibiotics. Enterococcus faecalis is an opportunistic pathogen that readily forms biofilms and also has the propensity to acquire resistance determinants via horizontal gene transfer. There is intense interest in the genetic basis for intrinsic and acquired antibiotic resistance in E. faecalis, since clinical isolates exhibiting resistance to multiple antibiotics are not uncommon. We performed a genetic screen using a library of transposon (Tn) mutants to identify E. faecalis biofilm-associated antibiotic resistance determinants. Five Tn mutants formed wild-type biofilms in the absence of antibiotics but produced decreased biofilm biomass in the presence of antibiotic concentrations that were subinhibitory to the parent strain. Genetic determinants responsible for biofilm-associated antibiotic resistance include components of the quorum-sensing system (fsrA, fsrC, and gelE) and two glycosyltransferase (GTF) genes (epaI and epaOX). We also found that the GTFs play additional roles in E. faecalis resistance to detergent and bile salts, maintenance of cell envelope integrity, determination of cell shape, polysaccharide composition, and conjugative transfer of the pheromone-inducible plasmid pCF10. The epaOX gene is located in a variable extended region of the enterococcal polysaccharide antigen (epa) locus. These data illustrate the importance of GTFs in E. faecalis adaptation to diverse growth conditions and suggest new targets for antimicrobial design. PMID:25918141

  12. Microbial relatives of the seed storage proteins of higher plants: conservation of structure and diversification of function during evolution of the cupin superfamily.

    Science.gov (United States)

    Dunwell, J M; Khuri, S; Gane, P J

    2000-03-01

    This review summarizes the recent discovery of the cupin superfamily (from the Latin term "cupa," a small barrel) of functionally diverse proteins that initially were limited to several higher plant proteins such as seed storage proteins, germin (an oxalate oxidase), germin-like proteins, and auxin-binding protein. Knowledge of the three-dimensional structure of two vicilins, seed proteins with a characteristic beta-barrel core, led to the identification of a small number of conserved residues and thence to the discovery of several microbial proteins which share these key amino acids. In particular, there is a highly conserved pattern of two histidine-containing motifs with a varied intermotif spacing. This cupin signature is found as a central component of many microbial proteins including certain types of phosphomannose isomerase, polyketide synthase, epimerase, and dioxygenase. In addition, the signature has been identified within the N-terminal effector domain in a subgroup of bacterial AraC transcription factors. As well as these single-domain cupins, this survey has identified other classes of two-domain bicupins including bacterial gentisate 1, 2-dioxygenases and 1-hydroxy-2-naphthoate dioxygenases, fungal oxalate decarboxylases, and legume sucrose-binding proteins. Cupin evolution is discussed from the perspective of the structure-function relationships, using data from the genomes of several prokaryotes, especially Bacillus subtilis. Many of these functions involve aspects of sugar metabolism and cell wall synthesis and are concerned with responses to abiotic stress such as heat, desiccation, or starvation. Particular emphasis is also given to the oxalate-degrading enzymes from microbes, their biological significance, and their value in a range of medical and other applications.

  13. Role of Glycosyltransferases Modifying Type B Flagellin of Emerging Hypervirulent Clostridium difficile Lineages and Their Impact on Motility and Biofilm Formation.

    Science.gov (United States)

    Valiente, Esmeralda; Bouché, Laura; Hitchen, Paul; Faulds-Pain, Alexandra; Songane, Mario; Dawson, Lisa F; Donahue, Elizabeth; Stabler, Richard A; Panico, Maria; Morris, Howard R; Bajaj-Elliott, Mona; Logan, Susan M; Dell, Anne; Wren, Brendan W

    2016-12-02

    Clostridium difficile is the principal cause of nosocomial infectious diarrhea worldwide. The pathogen modifies its flagellin with either a type A or type B O-linked glycosylation system, which has a contributory role in pathogenesis. We study the functional role of glycosyltransferases modifying type B flagellin in the 023 and 027 hypervirulent C. difficile lineages by mutagenesis of five putative glycosyltransferases and biosynthetic genes. We reveal their roles in the biosynthesis of the flagellin glycan chain and demonstrate that flagellar post-translational modification affects motility and adhesion-related bacterial properties of these strains. We show that the glycosyltransferases 1 and 2 (GT1 and GT2) are responsible for the sequential addition of a GlcNAc and two rhamnoses, respectively, and that GT3 is associated with the incorporation of a novel sulfonated peptidyl-amido sugar moiety whose structure is reported in our accompanying paper (Bouché, L., Panico, M., Hitchen, P., Binet, D., Sastre, F., Faulds-Pain, A., Valiente, E., Vinogradov, E., Aubry, A., Fulton, K., Twine, S., Logan, S. M., Wren, B. W., Dell, A., and Morris, H. R. (2016) J. Biol. Chem. 291, 25439-25449). GT2 is also responsible for methylation of the rhamnoses. Whereas type B modification is not required for flagellar assembly, some mutations that result in truncation or abolition of the glycan reduce bacterial motility and promote autoaggregation and biofilm formation. The complete lack of flagellin modification also significantly reduces adhesion of C. difficile to Caco-2 intestinal epithelial cells but does not affect activation of human TLR5. Our study advances our understanding of the genes involved in flagellar glycosylation and their biological roles in emerging hypervirulent C. difficile strains. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Role of Glycosyltransferases Modifying Type B Flagellin of Emerging Hypervirulent Clostridium difficile Lineages and Their Impact on Motility and Biofilm Formation*

    Science.gov (United States)

    Valiente, Esmeralda; Bouché, Laura; Hitchen, Paul; Faulds-Pain, Alexandra; Songane, Mario; Dawson, Lisa F.; Donahue, Elizabeth; Stabler, Richard A.; Panico, Maria; Morris, Howard R.; Bajaj-Elliott, Mona; Logan, Susan M.; Dell, Anne; Wren, Brendan W.

    2016-01-01

    Clostridium difficile is the principal cause of nosocomial infectious diarrhea worldwide. The pathogen modifies its flagellin with either a type A or type B O-linked glycosylation system, which has a contributory role in pathogenesis. We study the functional role of glycosyltransferases modifying type B flagellin in the 023 and 027 hypervirulent C. difficile lineages by mutagenesis of five putative glycosyltransferases and biosynthetic genes. We reveal their roles in the biosynthesis of the flagellin glycan chain and demonstrate that flagellar post-translational modification affects motility and adhesion-related bacterial properties of these strains. We show that the glycosyltransferases 1 and 2 (GT1 and GT2) are responsible for the sequential addition of a GlcNAc and two rhamnoses, respectively, and that GT3 is associated with the incorporation of a novel sulfonated peptidyl-amido sugar moiety whose structure is reported in our accompanying paper (Bouché, L., Panico, M., Hitchen, P., Binet, D., Sastre, F., Faulds-Pain, A., Valiente, E., Vinogradov, E., Aubry, A., Fulton, K., Twine, S., Logan, S. M., Wren, B. W., Dell, A., and Morris, H. R. (2016) J. Biol. Chem. 291, 25439–25449). GT2 is also responsible for methylation of the rhamnoses. Whereas type B modification is not required for flagellar assembly, some mutations that result in truncation or abolition of the glycan reduce bacterial motility and promote autoaggregation and biofilm formation. The complete lack of flagellin modification also significantly reduces adhesion of C. difficile to Caco-2 intestinal epithelial cells but does not affect activation of human TLR5. Our study advances our understanding of the genes involved in flagellar glycosylation and their biological roles in emerging hypervirulent C. difficile strains. PMID:27703012

  15. The root endophyte fungus Piriformospora indica leads to early flowering, higher biomass and altered secondary metabolites of the medicinal plant, Coleus forskohlii.

    Science.gov (United States)

    Das, Aparajita; Kamal, Shwet; Shakil, Najam Akhtar; Sherameti, Irena; Oelmüller, Ralf; Dua, Meenakshi; Tuteja, Narendra; Johri, Atul Kumar; Varma, Ajit

    2012-01-01

    This study was undertaken to investigate the influence of plant probiotic fungus Piriformospora indica on the medicinal plant C. forskohlii. Interaction of the C. forskohlii with the root endophyte P. indica under field conditions, results in an overall increase in aerial biomass, chlorophyll contents and phosphorus acquisition. The fungus also promoted inflorescence development, consequently the amount of p-cymene in the inflorescence increased. Growth of the root thickness was reduced in P. indica treated plants as they became fibrous, but developed more lateral roots. Because of the smaller root biomass, the content of forskolin was decreased. The symbiotic interaction of C. forskohlii with P. indica under field conditions promoted biomass production of the aerial parts of the plant including flower development. The plant aerial parts are important source of metabolites for medicinal application. Therefore we suggest that the use of the root endophyte fungus P. indica in sustainable agriculture will enhance the medicinally important chemical production.

  16. Immune Responses and Protection against Experimental Challenge after Vaccination of Bison with Brucella abortus Strain RB51 or RB51 Overexpressing Superoxide Dismutase and Glycosyltransferase Genes▿

    OpenAIRE

    Olsen, S. C.; Boyle, S. M.; Schurig, G. G.; Sriranganathan, N. N.

    2009-01-01

    Vaccination is a tool that could be beneficial in managing the high prevalence of brucellosis in free-ranging bison in Yellowstone National Park. In this study, we characterized immunologic responses and protection against experimental challenge after vaccination of bison with Brucella abortus strain RB51 (RB51) or a recombinant RB51 strain overexpressing superoxide dismutase (sodC) and glycosyltransferase (wboA) genes (RB51+sodC,wboA). Bison were vaccinated with saline only or with 4.6 × 101...

  17. Site-saturation engineering of lysine 47 in cyclodextrin glycosyltransferase from Paenibacillus macerans to enhance substrate specificity towards maltodextrin for enzymatic synthesis of 2-O-D-glucopyranosyl-L-ascorbic acid (AA-2G).

    Science.gov (United States)

    Han, Ruizhi; Liu, Long; Shin, Hyun-dong; Chen, Rachel R; Du, Guocheng; Chen, Jian

    2013-07-01

    In this work, the site-saturation engineering of lysine 47 in cyclodextrin glycosyltransferase (CGTase) from Paenibacillus macerans was conducted to improve the specificity of CGTase towards maltodextrin, which can be used as a cheap and easily soluble glycosyl donor for the enzymatic synthesis of 2-O-D-glucopyranosyl-L-ascorbic acid (AA-2G) by CGTase. When using maltodextrin as glycosyl donor, four mutants K47F (lysine→ phenylalanine), K47L (lysine→ leucine), K47V (lysine→ valine) and K47W (lysine→ tryptophan) showed higher AA-2G yield as compared with that produced by the wild-type CGTase. The transformation conditions (temperature, pH and the mass ratio of L-ascorbic acid to maltodextrin) were optimized and the highest titer of AA-2G produced by the mutant K47L could reach 1.97 g/l, which was 64.2% higher than that (1.20 g/l) produced by the wild-type CGTase. The reaction kinetics analysis confirmed the enhanced maltodextrin specificity, and it was also found that compared with the wild-type CGTase, the four mutants had relatively lower cyclization activities and higher disproportionation activities, which was favorable for AA-2G synthesis. The mechanism responsible for the enhanced substrate specificity was further explored by structure modeling and it was indicated that the enhancement of maltodextrin specificity may be due to the short residue chain and the removal of hydrogen bonding interactions between the side chain of residue 47 and the sugar at -3 subsite. Here the obtained mutant CGTases, especially the K47L, has a great potential in the production of AA-2G with maltodextrin as a cheap and easily soluble substrate.

  18. Cyclodextrin glycosyltransferase production by new Bacillus sp. strains isolated from brazilian soil

    Science.gov (United States)

    Menocci, Vivian; Goulart, Antonio José; Adalberto, Paulo Roberto; Tavano, Olga Luisa; Marques, Daniela Parreira; Contiero, Jonas; Monti, Rubens

    2008-01-01

    Three strains of Bacillus sp. (BACRP, BACNC-1 and BACAR) were isolated from soil adhered to cassava husk. CGTase specific activity for the three isolated strains was higher when cultivated at 40°C. Potato starch, cassava starch, maltodextrin and glucose were used as carbon source and growth temperatures varied from 25 to 55°C. The three isolates presented higher CGTase specific activity when cultivated with potato starch at 40°C. Isolated BACRP and BACAR presented specific activity of 4.0×10–3 and 2.2×10–3 U/mg prot at pH 7.0, respectively, when cultivated in mediums added with NaCl 2%; at pH 10,0 their activities were of 3.4×10–3 and 3.0×10–3 U/mg prot, respectively, in the same concentration of NaCl. On the other hand, the isolated BACNC-1 presented activity specific of 2.4×10–3 U/mg prot when cultivated at pH 7.0 added of NaCl 1%, and at pH 10.0 the specific activity was of 3.4×10–3 U/mg prot without NaCl addition. This work also showed the presence of cyclodextrins formed during fermentation process and that precipitation with acetone or lyophilization followed by dialysis was efficient at removing CDs (cyclodextrins), thus, eliminating interference in the activity assays. The enzyme produced by the BACAR strain was partially purified and β-CD was liberated as a reaction product. PMID:24031289

  19. Characterization of cysteine-degrading and H2S-releasing enzymes of higher plants - From the field to the test tube and back

    DEFF Research Database (Denmark)

    Jutta, Papenbrock; Anja, Riemenschneider; Kamp, Anja

    2007-01-01

    Due to the clean air acts and subsequent reduction of emission of gaseous sulfur compounds sulfur deficiency became one of the major nutrient disorders in Northern Europe. Typical sulfur deficiency symptoms can be diagnosed. Especially plants of the Cruciferae family are more susceptible against...... pathogen attack. Sulfur fertilization can in part recover or even increase resistance against pathogens in comparison to sulfur-deficient plants. The term sulfur-induced resistance (SIR) was introduced, however, the molecular basis for SIR is largely unknown. There are several sulfur-containing compounds...... in plants which might be involved in SIR, such as high levels of thiols, glucosinolates, cysteine-rich proteins, phytoalexins, elemental sulfur, or H2S. Probably more than one strategy is used by plants. Species- or even variety-dependent differences in the development of SIR are probably used. Our research...

  20. Triterpenoid Biosynthesis and Engineering in Plants

    Science.gov (United States)

    Sawai, Satoru; Saito, Kazuki

    2011-01-01

    Triterpenoid saponins are a diverse group of natural products in plants and are considered defensive compounds against pathogenic microbes and herbivores. Because of their various beneficial properties for humans, saponins are used in wide-ranging applications in addition to medicinally. Saponin biosynthesis involves three key enzymes: oxidosqualene cyclases, which construct the basic triterpenoid skeletons; cytochrome P450 monooxygenases, which mediate oxidations; and uridine diphosphate-dependent glycosyltransferases, which catalyze glycosylations. The discovery of genes committed to saponin biosynthesis is important for the stable supply and biotechnological application of these compounds. Here, we review the identified genes involved in triterpenoid biosynthesis, summarize the recent advances in the biotechnological production of useful plant terpenoids, and discuss the bioengineering of plant triterpenoids. PMID:22639586

  1. Potential physiological role of plant glycosidase inhibitors

    DEFF Research Database (Denmark)

    Bellincampi, D.; Carmadella, L.; Delcour, J.A.

    2004-01-01

    Carbohydrate-active enzymes including glycosidases, transglycosidases, glycosyltransferases, polysaccharide lyases and carbohydrate esterases are responsible for the enzymatic processing of carbohydrates in plants. A number of carbohydrate-active enzymes are produced by microbial pathogens...... and insects responsible of severe crop losses. Plants have evolved proteinaceous inhibitors to modulate the activity of several of these enzymes. The continuing discovery of new inhibitors indicates that this research area is still unexplored and may lead to new exciting developments. To date, the role...... of the inhibitors is not completely understood. Here we review recent results obtained on the best characterised inhibitors, pointing to their possible biological role in vivo. Results recently obtained with plant transformation technology indicate that this class of inhibitors has potential biotechnological...

  2. Subcellular Targeting of Proteins Involved in Modification of Plant N- and O-Glycosylation.

    Science.gov (United States)

    Dicker, Martina; Schoberer, Jennifer; Vavra, Ulrike; Strasser, Richard

    2015-01-01

    Plants are attractive expression hosts for the production of recombinant glycoprotein therapeutics. The quality and efficiency of these biopharmaceuticals are very often influenced by the glycosylation profile. Consequently, approaches are needed that enable the production of recombinant glycoproteins with customized and homogenous N- and O-glycan structures. Here, we describe convenient tools that allow targeting and retention of glycan-modifying enzymes in the early secretory pathway of plants. These protocols can be used to fine-tune the subcellular localization of glycosyltransferases and glycosidases in plants and consequently to increase the homogeneity of glycosylation on recombinant glycoproteins.

  3. Large-scale changes in the abundance of common higher plant species across Britain between 1978, 1990 and 1998 as a consequence of human activity: Tests of hypothesised changes in trait representation

    NARCIS (Netherlands)

    Smart, S.M.; Bunce, R.G.H.; Marrs, R.; LeDuc, M.; Firbank, L.G.; Maskell, L.C.; Scott, W.A.; Thompson, K.; Walker, K.J.

    2005-01-01

    Presence of higher plant species was recorded in 1455 permanently marked quadrats located across Britain in 1978, 1990 and 1998 in a stratified, random sample of 259 1 km squares. Significant increases and decreases in frequency of each species were summarised as changes in the representation of

  4. Methylotrophic bacteria symbiosis with the higher plants as means of minimization of the lower hydrocarbons concentration during artificial ecosystem gas exchange

    Science.gov (United States)

    Berkovich, Yuliy; Smolyanina, Svetlana; Moukhamedieva, Lana; Mardanov, Robert; Doronina, Nina; Ivanova, Ekaterina

    Plant growth unit should be included in the LSS for the space vehicles for vitamin greens supply and psychological support of cosmonauts during long-term missions. The lower hydrocarbons such as methane, methanol, methylated sulfuric compounds and methylated amines, ethylene and so on, are the natural products of human and plant metabolism and usually considered as the air pollutions. It is shown, that one way to decrease the lower hydrocarbons concentration in the artificial ecosystems could be colonization of the plants by methylotrophic bacteria. The aerobic methylotrophic bacteria possess unique ability to use methane and its oxidized or replaced derivatives without food damage and human, animals or plants infection. We have found that methylotrophic bacteria are the phyto-symbiotic bacteria: they stimulate growth and development of the colonized plants because of synthesizing cytokinins and auxins, and vitamin B12.Two collection strains of the obligate methylotrophic bacteria - Methylovorus mays C and Methylomonas metanica S - were chosen because of their high activity to assimilate the lower hydrocarbons due to functioning of methanoldehydrogenase, methanmonooxigenase and ribulose monophosphate cycle enzymes system.Colonization of the leaf cabbage Brassica chinensis L. by these strains led to approximately 30 % reduce of methanol and methane concentration in the air inside phytotron. Experimental estimations of the influence of methylotrophic bacteria on leafy greens growth and development are obtained.

  5. Characterization of cysteine-degrading and H2S-releasing enzymes of higher plants - from the field to the test tube and back.

    Science.gov (United States)

    Papenbrock, J; Riemenschneider, A; Kamp, A; Schulz-Vogt, H N; Schmidt, A

    2007-09-01

    Due to the clean air acts and subsequent reduction of emission of gaseous sulfur compounds sulfur deficiency became one of the major nutrient disorders in Northern Europe. Typical sulfur deficiency symptoms can be diagnosed. Especially plants of the Cruciferae family are more susceptible against pathogen attack. Sulfur fertilization can in part recover or even increase resistance against pathogens in comparison to sulfur-deficient plants. The term sulfur-induced resistance (SIR) was introduced, however, the molecular basis for SIR is largely unknown. There are several sulfur-containing compounds in plants which might be involved in SIR, such as high levels of thiols, glucosinolates, cysteine-rich proteins, phytoalexins, elemental sulfur, or H2S. Probably more than one strategy is used by plants. Species- or even variety-dependent differences in the development of SIR are probably used. Our research focussed mainly on the release of H2S as defence strategy. In field experiments using different BRASSICA NAPUS genotypes it was shown that the genetic differences among BRASSICA genotypes lead to differences in sulfur content and L-cysteine desulfhydrase activity. Another field experiment demonstrated that sulfur supply and infection with PYRENOPEZIZA BRASSICA influenced L-cysteine desulfhydrase activity in BRASSICA NAPUS. Cysteine-degrading enzymes such as cysteine desulfhydrases are hypothesized to be involved in H2S release. Several L- and D-cysteine-specific desulfhydrase candidates have been isolated and partially analyzed from the model plant ARABIDOPSIS THALIANA. However, it cannot be excluded that H2S is also released in a partial back reaction of O-acetyl-L-serine(thiol)lyase or enzymes not yet characterized. For the exact determination of the H2S concentration in the cell a H2S-specific microsensor was used the first time for plant cells. The transfer of the results obtained for application back on BRASSICA was initiated.

  6. Use of human wastes oxidized to different degrees in cultivation of higher plants on the soil-like substrate intended for closed ecosystems

    Science.gov (United States)

    Tikhomirov, A. A.; Kudenko, Yu. A.; Ushakova, S. A.; Tirranen, L. S.; Gribovskaya, I. A.; Gros, J.-B.; Lasseur, Ch.

    2010-09-01

    To close mass exchange loops in bioregenerative life support systems more efficiently, researchers of the Institute of Biophysics SB RAS (Krasnoyarsk, Russia) have developed a procedure of wet combustion of human wastes and inedible parts of plants using H 2O 2 in alternating electromagnetic field. Human wastes pretreated in this way can be used as nutrient solutions to grow plants in the phototrophic unit of the LSS. The purpose of this study was to explore the possibilities of using human wastes oxidized to different degrees to grow plants cultivated on the soil-like substrate (SLS). The treated human wastes were analyzed to test their sterility. Then we investigated the effects produced by human wastes oxidized to different degrees on growth and development of wheat plants and on the composition of microflora in the SLS. The irrigation solution contained water, substances extracted from the substrate, and certain amounts of the mineralized human wastes. The experiments showed that the human wastes oxidized using reduced amounts of 30% H 2O 2: 1 ml/g of feces and 0.25 ml/ml of urine were still sterile. The experiments with wheat plants grown on the SLS and irrigated by the solution containing treated human wastes in the amount simulating 1/6 of the daily diet of a human showed that the degree of oxidation of human wastes did not significantly affect plant productivity. On the other hand, the composition of the microbiota of irrigation solutions was affected by the oxidation level of the added metabolites. In the solutions supplemented with partially oxidized metabolites yeast-like microscopic fungi were 20 times more abundant than in the solutions containing fully oxidized metabolites. Moreover, in the solutions containing incompletely oxidized human wastes the amounts of phytopathogenic bacteria and denitrifying microorganisms were larger. Thus, insufficiently oxidized sterile human wastes added to the irrigation solutions significantly affect the composition of

  7. Molecular and functional analysis of phosphomannomutase (PMM) from higher plants and genetic evidence for the involvement of PMM in ascorbic acid biosynthesis in Arabidopsis and Nicotiana benthamiana

    DEFF Research Database (Denmark)

    Qian, W; Yu, C; Qin, H

    2007-01-01

    was constitutively expressed in both vegetative and reproductive organs. Reducing the PMM expression level through virus-induced gene silencing caused a substantial decrease in ascorbic acid (AsA) content in N. benthamiana leaves. Conversely, raising the PMM expression level in N. benthamiana using viral......, soybean, tomato, rice and wheat. Amino acid sequence comparisons indicated that plant PMM proteins exhibited significant identity to their fungal and mammalian orthologs. In line with the similarity in primary structure, plant PMM complemented the sec53-6 temperature sensitive mutant of Saccharomyces...

  8. Materials for higher steam temperatures (up to 600 deg C) in biomass and waste fired plant. A review of present knowledge; Material foer hoegre aangtemperaturer (upp till 600 grader C) i bio- och avfallseldade anlaeggningar

    Energy Technology Data Exchange (ETDEWEB)

    Staalenheim, Annika; Henderson, Pamela

    2011-02-15

    A goal for the Swedish power industry is to build a demonstration biomass-fired plant with 600 deg C steam data in 2015. Vaermeforsk also has a goal to identify materials that can be used in such a plant. This project involves a survey of present knowledge and published articles concerning materials that are suitable for use in biomass and wastefired plants with steam data up to 600 deg C. The information has been gathered from plants presently in operation, and from field tests previously performed with probes. Plants firing only household waste are excluded. The components considered are waterwalls/furnace walls (affected because of higher steam pressures) and superheaters. Fireside corrosion and steam-side oxidation are dealt with. Candidate materials (or coatings) are suggested and areas for further research have been identified. The purpose of this project is to give state-of-the-art information on what materials could be used in biomass and waste-fired plant to reach a maximum steam temperature of 600 deg C. This report is aimed at suppliers of boilers and materials, energy utility companies and others involved in building new plant with higher steam data. In accordance with the goals of this project: - Materials suitable for use at higher steam temperatures (up to 600 deg C steam) in wood-based biomass and waste-fired plant have been identified. Austenitic stainless steels HR3C, TP 347 HFG and AC66 all have adequate strength, steam-side oxidation and fireside corrosion resistance for use as superheaters. AC66 and HR3C have better steam-side oxidation resistance than TP 347 HFG , but TP 347 HFG has better fireside corrosion resistance. It is recommended that TP 347 HFG be shot-peened on the inside to improve the oxidation resistance if in service with steam temperatures above 580 deg C. - Furnace walls coated with Ni-based alloys or a mixture of Ni- alloy and ceramic show good corrosion resistance at lower temperatures and should be evaluated at higher

  9. Reduction of starch granule size by expression of an engineered tandem starch-binding domain in potato plants.

    Science.gov (United States)

    Ji, Qin; Oomen, Ronald J F J; Vincken, Jean-Paul; Bolam, David N; Gilbert, Harry J; Suurs, Luc C J M; Visser, Richard G F

    2004-05-01

    Granule size is an important parameter when using starch in industrial applications. An artificial tandem repeat of a family 20 starch-binding domain (SBD2) was engineered by two copies of the SBD derived from Bacillus circulans cyclodextrin glycosyltransferase via the Pro-Thr-rich linker peptide from Xyn10A from Cellulomonas fimi. SBD2 and a single SBD were introduced into the amylose-free potato mutant, amf, using appropriate signal sequences. The accumulation of SBD2 into transgenic starch granules was much higher than that of SBD. In a number of transformants, particularly amfSS3, the starch granules were much smaller than in control plants. The amfSS3 mean granule size was 7.8 microm, compared with 15.2 microm in the control, whereas other starch properties were unaltered. This new starch combines the advantage of the high purity of potato starch with that of the small granule size of other crop species, such as cassava, taro and wheat. This starch may find application in the manufacture of biodegradable plastic films. Both genes were also expressed in Escherichia coli and the affinity for soluble starch of the purified recombinant proteins was determined. SBD2 had an approximately 10-fold higher affinity for starch than SBD, indicating that the two appended SBDs act in synergy when binding to their target polysaccharide ligand.

  10. Rare ginsenoside Ia synthesized from F1 by cloning and overexpression of the UDP-glycosyltransferase gene from Bacillus subtilis: synthesis, characterization, and in vitro melanogenesis inhibition activity in BL6B16 cells

    Directory of Open Access Journals (Sweden)

    Dan-Dan Wang

    2018-01-01

    Conclusion: To our knowledge, this is the first study to report on the mass production of rare ginsenoside Ia from F1 using recombinant UDP-glycosyltransferase isolated from B. subtillis and its superior melanogenesis inhibitory activity in B16BL6 cells as compared to its precursor. In brief, ginsenoside Ia can be applied for further study in cosmetics.

  11. Enhanced production of steviol glycosides in mycorrhizal plants: a concerted effect of arbuscular mycorrhizal symbiosis on transcription of biosynthetic genes.

    Science.gov (United States)

    Mandal, Shantanu; Upadhyay, Shivangi; Singh, Ved Pal; Kapoor, Rupam

    2015-04-01

    Stevia rebaudiana (Bertoni) produces steviol glycosides (SGs)--stevioside (stev) and rebaudioside-A (reb-A) that are valued as low calorie sweeteners. Inoculation with arbuscular mycorrhizal fungi (AMF) augments SGs production, though the effect of this interaction on SGs biosynthesis has not been studied at molecular level. In this study transcription profiles of eleven key genes grouped under three stages of the SGs biosynthesis pathway were compared. The transcript analysis showed upregulation of genes encoding 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway enzymes viz.,1-deoxy-D-xylulose 5-phospate synthase (DXS), 1-deoxy-D-xylulose 5-phospate reductoisomerase (DXR) and 2-C-methyl-D-erytrithol 2,4-cyclodiphosphate synthase (MDS) in mycorrhizal (M) plants. Zn and Mn are imperative for the expression of MDS and their enhanced uptake in M plants could be responsible for the increased transcription of MDS. Furthermore, in the second stage of SGs biosynthesis pathway, mycorrhization enhanced the transcription of copalyl diphosphate synthase (CPPS) and kaurenoic acid hydroxylase (KAH). Their expression is decisive for SGs biosynthesis as CPPS regulates flow of metabolites towards synthesis of kaurenoid precursors and KAH directs these towards steviol synthesis instead of gibberellins. In the third stage glucosylation of steviol to reb-A by four specific uridine diphosphate (UDP)-dependent glycosyltransferases (UGTs) occurs. While higher transcription of all the three characterized UGTs in M plants explains augmented production of SGs; higher transcript levels of UGT76G1, specifically improved reb-A to stev ratio implying increased sweetness. The work signifies that AM symbiosis upregulates the transcription of all eleven SGs biosynthesis genes as a result of improved nutrition and enhanced sugar concentration due to increased photosynthesis in M plants. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  12. Plant planting

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes planting activities on Neal Smith National Wildlife Refuge (formerly Walnut Creek National Wildlife Refuge) between 1995 and 2009.

  13. Collection and conversion of silicon furnace waste gas into higher value products: Phase 3, 6 MW pilot plant dc closed furnace technology. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Dosaj, V.D.

    1995-01-01

    The construction and operation of a 6 MW, closed dc furnace for smelting silicon was the primary focus of Phase 3. A 6 MW, dc closed furnace pilot plant was built in East Selkirk, Manitoba, Canada. The furnace is equipped with world`s most modern automatic control system used to control and monitor the process variables and operational data. This control system is suitable for commercial applications and could be used with either closed or open dc furnaces for smelting silicon or ferrosilicon. The construction was started in September 1990, and the facility was operational within 18 months. Following successful commissioning of the pilot plant in June 1992, twelve smelting test campaigns were conducted through November 1994.

  14. [Comparative evaluation of productivity of several green cultures as potential higher plant components of bio-regenerative systems of life support].

    Science.gov (United States)

    Ushakova, S A; Tikhomirov, A A; Velichko, V V; Golovko, T G; Tabalenkova, G N; Zakhozhiĭ, I G; Matusevich, V V

    2010-01-01

    Purpose of the investigation was to select, analyze and evaluate green plant species known for assisting resistance to diseases and improving physiological functions in humans, and to test allelopathic compatibility of selected species with basic systems for life support. Nutrient substrates were freshly made soil-like substrate (SLS) and clayite. Green cultures were 6 spinach species, 2 lettuces, 2 leaf cabbage species and ruccola. The investigations showed that plant productivity was either equal to or better on freshly made SLS than on clayite; however, the greens accumulated large quantities of nitrate nitrogen. The highest productivity distinguished leaf cabbage; the best antiradical properties was demonstrated by lettuces and the worst, by some spinach species. None of the species displayed a negative allelopathic effect on productivity of the reddish test culture.

  15. European Court establishes higher hurdles for the realisation of waste incineration and recycling plants; EuGH schafft noch hoehere Huerden fuer die Realisierung von Muellverbrennungs- und Recyclinganlagen

    Energy Technology Data Exchange (ETDEWEB)

    Faber, Tobias; Rieger, Alexander Stefan [Hogan Lovells International LLP, Frankfurt am Main (Germany)

    2011-07-15

    'The European Court of Justice (ECJ) established in a well-noted decision (C-115/09) new hurdles for the realisation of waste projects. As a consequence of its decision, the rights of action of environmental associations against industrial infrastructure projects have been strengthened significantly. They are now allowed to take extensive legal actions regarding the compliance with environmental law in permit procedures as 'lawyers of the nature' - actions which have already been announced in the press. The new rights particularly affect waste incineration plants, recycling plants, waste-to-energy power plants, recycling depots and any further waste projects. It is expected that the current decision encourages excessive litigation against - often unpopular - waste projects. This causes new problems for the realisation and the financing of such projects: The permit procedures will get more complicated, a broader participation of the general public will be necessary, project costs will rise and the project realisation will take longer. In summary, the project risks are rising. Thus, this means for all project related parties, that they need to identify the aforementioned risks in order to allocate them and adapt them in the contractual wording reasonably: In particular this includes provisions for termination, further compensation and withdrawal from the contract in case of a late, cancelled or rejected permit. (orig.)

  16. The N-terminus of Vps74p is essential for the retention of glycosyltransferases in the Golgi but not for the modulation of apical polarized growth in Saccharomyces cerevisiae.

    Science.gov (United States)

    Hsu, Jia-Wei; Chang, Lin-Chun; Jang, Li-Ting; Huang, Chun-Fang; Lee, Fang-Jen S

    2013-01-01

    Vps74p is a member of the PtdIns(4)P-binding protein family. Vps74p interacts with Golgi-resident glycosyltransferases and the coat protein COPI complex to modulate Golgi retention of glycosyltransferases and with the PtdIns(4)P phosphatase Sac1p to modulate PtdIns(4)P homeostasis at the Golgi. Genetic analysis has shown that Vps74p is required for the formation of abnormal elongated buds in cdc34-2 cells. The C-terminal region of Vps74p is required for Vps74p multimerization, Golgi localization, and glycosyltransferase interactions; however, the functional significance of the N-terminal region and three putative phosphorylation sites of Vps74p have not been well characterized. In this study, we demonstrate that Vps74p executes multiple cellular functions using different domains. We found that the N-terminal 66 amino acids of Vps74p are dispensable for its Golgi localization and modulation of cell wall integrity but are required for glycosyltransferase retention and glycoprotein processing. Deletion of the N-terminal 90 amino acids, but not the 66 amino acids, of Vps74p impaired its ability to restore the elongated bud phenotype in cdc34-2/vps74Δ cells. Deletion of Sac1p and Arf1p also specifically reduced the abnormal elongated bud phenotype in cdc34-2 cells. Furthermore, we found that three N-terminal phosphorylation sites contribute to rapamycin hypersensitivity, although these phosphorylation residues are not involved in Vps74p localization, ability to modulate glycosyltransferase retention, or elongated bud formation in cdc34-2 cells. Thus, we propose that Vps74p may use different domains to interact with specific effectors thereby differentially modulating a variety of cellular functions.

  17. Using Tn-seq To Identify Pigmentation-Related Genes of Porphyromonas gingivalis: Characterization of the Role of a Putative Glycosyltransferase.

    Science.gov (United States)

    Klein, Brian A; Cornacchione, Louis P; Collins, Marisha; Malamy, Michael H; Duncan, Margaret J; Hu, Linden T

    2017-07-15

    Cellular pigmentation is an important virulence factor of the oral pathogen Porphyromonas gingivalis Pigmentation has been associated with many bacterial functions, including but not limited to colonization, maintaining a local anaerobic environment by binding oxygen molecules, and defense against reactive oxygen species (ROS) produced by immune cells. Pigmentation-associated loci identified to date have involved lipopolysaccharide, fimbriae, and heme acquisition and processing. We utilized a transposon mutant library of P. gingivalis strain ATCC 33277 and screened for pigmentation-defective colonies using massively parallel sequencing of the transposon junctions (Tn-seq) to identify genes involved in pigmentation. Transposon insertions at 235 separate sites, located in 67 genes and 15 intergenic regions, resulted in altered pigmentation: 7 of the genes had previously been shown to be involved in pigmentation, while 75 genes and intergenic regions had not. To further confirm identification, we generated a smaller transposon mutant library in P. gingivalis strain W83 and identified pigment mutations in several of the same loci as those identified in the screen in ATCC 33277 but also eight that were not identified in the ATCC 33277 screen. PGN_0361/PG_0264, a putative glycosyltransferase gene located between two tRNA synthetase genes and adjacent to a miniature inverted-repeat transposable element, was identified in the Tn-seq screen and then verified through targeted deletion and complementation. Deletion mutations in PGN_0361/PG_0264 glycosyltransferase abolish pigmentation, modulate gingipain protease activity, and alter lipopolysaccharide. The mechanisms of involvement in pigmentation for other loci identified in this study remain to be determined, but our screen provides the most complete survey of genes involved in pigmentation to date.IMPORTANCEP. gingivalis has been implicated in the onset and progression of periodontal disease. One important virulence factor

  18. Higher education

    OpenAIRE

    Wolter, Andrä

    2009-01-01

    During the last five years higher education research in Germany seems to be in a significant upturn. This is a side effect partly of the obvious boom of empirical educational research in general and partly of the reform movement that has affected the German higher education system since middle of the 1990s. The demand for data in the field of higher education will increase considerably in future. The available data infrastructure for higher education research in Germany consists of two comple...

  19. Expression of a Heterologous S-Adenosylmethionine Decarboxylase cDNA in Plants Demonstrates That Changes in S-Adenosyl-l-Methionine Decarboxylase Activity Determine Levels of the Higher Polyamines Spermidine and Spermine1

    Science.gov (United States)

    Thu-Hang, Pham; Bassie, Ludovic; Safwat, Gehan; Trung-Nghia, Pham; Christou, Paul; Capell, Teresa

    2002-01-01

    We posed the question of whether steady-state levels of the higher polyamines spermidine and spermine in plants can be influenced by overexpression of a heterologous cDNA involved in the later steps of the pathway, in the absence of any further manipulation of the two synthases that are also involved in their biosynthesis. Transgenic rice (Oryza sativa) plants engineered with the heterologous Datura stramonium S-adenosylmethionine decarboxylase (samdc) cDNA exhibited accumulation of the transgene steady-state mRNA. Transgene expression did not affect expression of the orthologous samdc gene. Significant increases in SAMDC activity translated to a direct increase in the level of spermidine, but not spermine, in leaves. Seeds recovered from a number of plants exhibited significant increases in spermidine and spermine levels. We demonstrate that overexpression of the D. stramonium samdc cDNA in transgenic rice is sufficient for accumulation of spermidine in leaves and spermidine and spermine in seeds. These findings suggest that increases in enzyme activity in one of the two components of the later parts of the pathway leading to the higher polyamines is sufficient to alter their levels mostly in seeds and, to some extent, in vegetative tissue such as leaves. Implications of our results on the design of rational approaches for the modulation of the polyamine pathway in plants are discussed in the general framework of metabolic pathway engineering. PMID:12177487

  20. Tocopherol quinone content of green algae and higher plants revised by a new high-sensitive fluorescence detection method using HPLC--effects of high light stress and senescence.

    Science.gov (United States)

    Kruk, Jerzy; Szymańska, Renata; Krupinska, Karin

    2008-08-25

    A rapid, sensitive fluorescence method was applied here for detection of oxidized tocopherol quinones in total plant tissue extracts using HPLC, employing a post-column reduction of these compounds by a Zn column. Using this method, we were able to detect both alpha- and gamma-tocopherol quinones in Chlamydomonas reinhardii with a very high degree of sensitivity. The levels of both compounds increased under high light stress in the presence of pyrazolate in parallel to a decrease in the content of the corresponding tocopherols. The formation of tocopherol quinones from tocopherols was apparently due to their oxidation by singlet oxygen, which is formed in photosystem II under high light stress. alpha-Tocopherol quinone was also detected in a variety of higher plants of different age, and its level was found to increase during senescence in leaves grown under natural conditions. In contrast to alpha-tocopherol quinone, gamma-tocopherol quinone was not found in the higher plant species investigated with the exception of young runner bean leaves, where the levels of both compounds increased dramatically during cold and light stress. Taking advantage of native fluorescence of the reduced alpha-tocopherol quinone (alpha-tocopherol quinol), it can be detected in plant tissue extracts with a high sensitivity. In young runner bean leaves, alpha-tocopherol quinol was found at a level similar to alpha-tocopherol.

  1. Vaccination of Elk (Cervus canadensis) with Brucella abortus Strain RB51 Overexpressing Superoxide Dismutase and Glycosyltransferase Genes Does Not Induce Adequate Protection against Experimental Brucella abortus Challenge.

    Science.gov (United States)

    Nol, Pauline; Olsen, Steven C; Rhyan, Jack C; Sriranganathan, Nammalwar; McCollum, Matthew P; Hennager, Steven G; Pavuk, Alana A; Sprino, Phillip J; Boyle, Stephen M; Berrier, Randall J; Salman, Mo D

    2016-01-01

    In recent years, elk (Cervus canadensis) have been implicated as the source of Brucella abortus infection for numerous cattle herds in the Greater Yellowstone Area. In the face of environmental and ecological changes on the landscape, the range of infected elk is expanding. Consequently, the development of effective disease management strategies for wild elk herds is of utmost importance, not only for the prevention of reintroduction of brucellosis to cattle, but also for the overall health of the Greater Yellowstone Area elk populations. In two studies, we evaluated the efficacy of B. abortus strain RB51 over-expressing superoxide dismutase and glycosyltransferase for protecting elk from infection and disease caused by B. abortus after experimental infection with a virulent B. abortus strain. Our data indicate that the recombinant vaccine does not protect elk against brucellosis. Further, work is needed for development of an effective brucellosis vaccine for use in elk.

  2. Engineering stategies and implications of using higher plants for throttling gas and water exchange in a controlled ecological life support system

    Science.gov (United States)

    Chamberland, Dennis; Wheeler, Raymond M.; Corey, Kenneth A.

    1993-01-01

    Engineering stategies for advanced life support systems to be used on Lunar and Mars bases involve a wide spectrum of approaches. These range from purely physical-chemical life support strategies to purely biological approaches. Within the context of biological based systems, a bioengineered system can be devised that would utilize the metabolic mechanisms of plants to control the rates of CO2 uptake and O2 evolution (photosynthesis) and water production (transpiration). Such a mechanism of external engineering control has become known as throttling. Research conducted at the John F. Kennedy Space Center's Controlled Ecological Life Support System Breadboard Project has demonstrated the potential of throttling these fluxes by changing environmental parameters affecting the plant processes. Among the more effective environmental throttles are: light and CO2 concentration for controllingthe rate of photsynthesis and humidity and CO2 concentration for controlling transpiration. Such a bioengineered strategy implies control mechanisms that in the past have not been widely attributed to life support systems involving biological components and suggests a broad range of applications in advanced life support system design.

  3. Tracing atmospheric transport of soil microorganisms and higher plant waxes in the East Asian outflow to the North Pacific Rim by using hydroxy fatty acids: Year-round observations at Gosan, Jeju Island

    Science.gov (United States)

    Tyagi, Poonam; Kawamura, Kimitaka; Kariya, Tadashi; Bikkina, Srinivas; Fu, Pingqing; Lee, Meehye

    2017-04-01

    Atmospheric transport of soil microorganisms and higher plant waxes in East Asia significantly influences the aerosol composition over the North Pacific. This study investigates the year-round atmospheric abundances of hydroxy fatty acids (FAs), tracers of soil microorganisms (β-isomers), and plant waxes (α- and ω-isomers), in total suspended particles collected at Gosan, Jeju Island, during April 2001 to March 2002. These hydroxy FAs showed a pronounced seasonality, higher concentrations in winter/spring and lower concentrations in summer/autumn, which are consistent with other tracers of soil microbes (trehalose), resuspended dust (nss-Ca2+), and stable carbon isotopic composition (δ13C) of total carbon. The molecular distributions of β-hydroxy FAs (predominance of C12 and C16 in winter/spring and summer/autumn, respectively) are consistent with those from a remote island (Chichijima) in the North Pacific and Asian dust standards (CJ-1 and CJ-2). This observation together with back trajectories over Gosan reveal that desert sources in China during winter and arid regions of Mongolia and Russian Far East during spring are the major contributors of soil microbes over the North Pacific. Predominance of ω-isomers (83%) over β-hydroxy FAs (16%) revealed a major contribution of terrestrial lipids from higher plant waxes over soil microbes in the East Asian outflow.

  4. A common registration-to-publication automated pipeline for nomenclatural acts for higher plants (International Plant Names Index, IPNI), fungi (Index Fungorum, MycoBank) and animals (ZooBank)

    NARCIS (Netherlands)

    Robert, Vincent

    2016-01-01

    Collaborative effort among four lead indexes of taxon names and nomenclatural acts (International Plant Name Index (IPNI), Index Fungorum, MycoBank and ZooBank) and the journals PhytoKeys, MycoKeys and ZooKeys to create an automated, pre-publication, registration workflow, based on a

  5. Fungitoxicity of some higher plants and synergistic activity of their essential oils against Sclerotium rolfsii sacc. causing foot-rot disease of barley.

    Science.gov (United States)

    Singh, R K

    Twenty five plant species were screened for their volatile components against hyphal growth and sclerotia formation of Sclerotium rolfsii causing foot rot disease of barley (Hordeum vulgare). Leaves of Chenopodium ambrosioides (CA), Lippia alba (LA), Azadirachta indica (AI) and Eucalyptus globulus (EG) were found to be strongly toxic. Their volatile active factors were isolated in the form of essential oils which were tested for toxicity individually and in six combinations (1:1 v/v) viz. CA-LA, LA-AI, CA-AI, CA-EG, and EG-AI. The oil combinations were found to be more fungitoxic than the individual oils. The CA-LA, LA-AI, EG-AI, and CA-EG combinations exhibited a broad fnngitoxic spectrum while CA-AI, LA-EG combinations possessed a narrow range of toxicity. None of the six oil combinations showed phytotoxic behaviour on seed germination, seedling growth and general morphology of Hordeum vulgare.

  6. ER import sites and their relationship to ER exit sites: a new model for bidirectional ER-Golgi transport in higher plants

    Directory of Open Access Journals (Sweden)

    Alexander eLerich

    2012-07-01

    Full Text Available The plant Golgi apparatus is polydisperse and COPII fluorescence localizes to the interface between the ER and the overlying Golgi stack rather than the surface of the ER. Per definition, ER exit sites (ERES are COPII vesiculation events at the surface of the ER and are only visualizable in the electron microscope through cryofixation techniques. Nevertheless, ERES is always associated with Golgi stacks and both move together. We have asked whether the domain of the ER where retrograde COPI vesicles fuse, i.e. ER import sites, (ERIS, is also coupled to Golgi stack motility and therefore spatially associated with ERES? As ERIS markers we have investigated ER-located SNAREs and tethering factors. We screened several SNAREs (SYP81, the SYP7 family, and USE1 to find a SNARE whose overexpression did not disrupt ER-Golgi traffic and which gave rise to discrete fluorescent punctae when expressed with an XFP tag. Only the Qc SNARE SYP72 fulfilled these criteria, and, based on quantitative protein transport assays with the retrograde reporter α-amylase-HDEL, even appeared to enhance retrograde traffic. When coexpressed with SYP72-YFP, the type I membrane protein RFP-p24δ5 whose ER localization is due to an efficient COPI-mediated recycling, forms nodules along the tubular ER network. SYP72 colocalizes with these nodules which are not seen when RFP-p24δ5 is expressed alone or when SYP72-YFP is coexpressed with a mutant form of RFP-p24δ5 that cannot exit the ER. Immobilized Golgi stacks show a perfect colocalization between SYP72-YFP and fluorescent COPII/Golgi markers. Endogenous SYP72, also colocalizes with COPII/Golgi. Fluorescently tagged versions of plant homologs to TIP20 of the Dsl1 COPI-tethering factor complex, and to the COPII-tethering factor p115 both colocalize perfectly with Golgi stacks. These data suggest that ERES, ERIS and Golgi stacks are closely associated thereby constituting a mobile secretory and recycling unit: a unique feature

  7. Suppression of the invasive plant mile-a-minute (Mikania micrantha) by local crop sweet potato (Ipomoea batatas) by means of higher growth rate and competition for soil nutrients.

    Science.gov (United States)

    Shen, Shicai; Xu, Gaofeng; Clements, David Roy; Jin, Guimei; Chen, Aidong; Zhang, Fudou; Kato-Noguchi, Hisashi

    2015-01-28

    There are a variety of ways of increasing crop diversity to increase agricultural sustainability and in turn having a positive influence on nearby natural ecosystems. Competitive crops may provide potent management tools against invasive plants. To elucidate the competitive mechanisms between a sweet potato crop (Ipomoea batatas) and an invasive plant, mile-a-minute (Mikania micrantha), field experiments were carried out in Longchuan County of Yunnan Province, Southwest China, utilizing a de Wit replacement series. The trial incorporated seven ratios of sweet potato and mile-a-minute plants in 25 m(2) plots. In monoculture, the total biomass, biomass of adventitious root, leafstalk length, and leaf area of sweet potato were all higher than those of mile-a-minute, and in mixed culture the plant height, branch, leaf, stem node, adventitious root, flowering and biomass of mile-a-minute were suppressed significantly (P replacement control methods which may apply to other crop-weed systems or invaded natural ecosystems.

  8. The Influence of Nitrate and Chloride Uptake on Expressed Sap pH, Organic Acid Synthesis, and Potassium Accumulation in Higher Plants.

    Science.gov (United States)

    Blevins, D G; Hiatt, A J; Lowe, R H

    1974-07-01

    The influence of NO(3) (-) uptake and reduction on ionic balance in barley seedlings (Hordeum vulgare, cv. Compana) was studied. KNO(3) and KCl treatment solutions were used for comparison of cation and anion uptake. The rate of Cl(-) uptake was more rapid than the rate of NO(3) (-) uptake during the first 2 to 4 hours of treatment. There was an acceleration in rate of NO(3) (-) uptake after 4 hours resulting in a sustained rate of NO(3) (-) uptake which exceeded the rate of Cl(-) uptake. The initial (2 to 4 hours) rate of K(+) uptake appeared to be independent of the rate of anion uptake. After 4 hours the rate of K(+) uptake was greater with the KNO(3) treatment than with the KCl treatment, and the solution pH, cell sap pH, and organic acid levels with KNO(3) increased, relative to those with the KCl treatment. When absorption experiments were conducted in darkness, K(+) uptake from KNO(3) did not exceed K(+) uptake from KCl. We suggest that the greater uptake and accumulation of K(+) in NO(3) (-)-treated plants resulted from (a) a more rapid, sustained uptake and transport of NO(3) (-) providing a mobile counteranion for K(+) transport, and (b) the synthesis of organic acids in response to NO(3) (-) reduction increasing the capacity for K(+) accumulation by providing a source of nondiffusible organic anions.

  9. A novel bioinformatics pipeline to discover genes related to arbuscular mycorrhizal symbiosis based on their evolutionary conservation pattern among higher plants.

    Science.gov (United States)

    Favre, Patrick; Bapaume, Laure; Bossolini, Eligio; Delorenzi, Mauro; Falquet, Laurent; Reinhardt, Didier

    2014-12-03

    Genes involved in arbuscular mycorrhizal (AM) symbiosis have been identified primarily by mutant screens, followed by identification of the mutated genes (forward genetics). In addition, a number of AM-related genes has been identified by their AM-related expression patterns, and their function has subsequently been elucidated by knock-down or knock-out approaches (reverse genetics). However, genes that are members of functionally redundant gene families, or genes that have a vital function and therefore result in lethal mutant phenotypes, are difficult to identify. If such genes are constitutively expressed and therefore escape differential expression analyses, they remain elusive. The goal of this study was to systematically search for AM-related genes with a bioinformatics strategy that is insensitive to these problems. The central element of our approach is based on the fact that many AM-related genes are conserved only among AM-competent species. Our approach involves genome-wide comparisons at the proteome level of AM-competent host species with non-mycorrhizal species. Using a clustering method we first established orthologous/paralogous relationships and subsequently identified protein clusters that contain members only of the AM-competent species. Proteins of these clusters were then analyzed in an extended set of 16 plant species and ranked based on their relatedness among AM-competent monocot and dicot species, relative to non-mycorrhizal species. In addition, we combined the information on the protein-coding sequence with gene expression data and with promoter analysis. As a result we present a list of yet uncharacterized proteins that show a strongly AM-related pattern of sequence conservation, indicating that the respective genes may have been under selection for a function in AM. Among the top candidates are three genes that encode a small family of similar receptor-like kinases that are related to the S-locus receptor kinases involved in sporophytic

  10. [Plant hormones, plant growth regulators].

    Science.gov (United States)

    Végvári, György; Vidéki, Edina

    2014-06-29

    Plants seem to be rather defenceless, they are unable to do motion, have no nervous system or immune system unlike animals. Besides this, plants do have hormones, though these substances are produced not in glands. In view of their complexity they lagged behind animals, however, plant organisms show large scale integration in their structure and function. In higher plants, such as in animals, the intercellular communication is fulfilled through chemical messengers. These specific compounds in plants are called phytohormones, or in a wide sense, bioregulators. Even a small quantity of these endogenous organic compounds are able to regulate the operation, growth and development of higher plants, and keep the connection between cells, tissues and synergy between organs. Since they do not have nervous and immume systems, phytohormones play essential role in plants' life.

  11. Higher Education.

    Science.gov (United States)

    Hendrickson, Robert M.

    This chapter reviews litigation in higher education for 1986. The first section discusses the relationship between postsecondary institutions and various governmental agencies, in which litigation covers questions on the authority of boards, access to information through sunshine laws, questions of tax exempt status, and issues of accreditation.…

  12. A DUF-246 family glycosyltransferase-like gene affects male fertility and the biosynthesis of pectic arabinogalactans

    DEFF Research Database (Denmark)

    Stonebloom, Solomon; Ebert, Berit; Xiong, Guangyan

    2016-01-01

    BACKGROUND: Pectins are a group of structurally complex plant cell wall polysaccharides whose biosynthesis and function remain poorly understood. The pectic polysaccharide rhamnogalacturonan-I (RG-I) has two types of arabinogalactan side chains, type-I and type-II arabinogalactans. To date few....... RESULTS: T-DNA insertions in PAGR were identified in Arabidopsis thaliana and were found to segregate at a 1:1 ratio of heterozygotes to wild type. We were unable to isolate homozygous pagr mutants as pagr mutant alleles were not transmitted via pollen. In vitro pollen germination assays revealed reduced...... expansion. Cell wall materials from NbPAGR-silenced plants had reduced galactose content compared to the control. Immunological and linkage analyses support that RG-I has reduced type-I arabinogalactan content and reduced branching of the RG-I backbone in NbPAGR-silenced plants. Arabidopsis lines...

  13. Evaluation of antioxidant capacity of 13 plant extracts by three different methods: cluster analyses applied for selection of the natural extracts with higher antioxidant capacity to replace synthetic antioxidant in lamb burgers.

    Science.gov (United States)

    Fernandes, R P P; Trindade, M A; Tonin, F G; Lima, C G; Pugine, S M P; Munekata, P E S; Lorenzo, J M; de Melo, M P

    2016-01-01

    The aims of this study were: to evaluate the total equivalent antioxidant capacities (TEAC) and phenolic contents of 13 plants extracts; to select the most promising extracts regarding reducing activity using cluster analysis multivariate statistical technique; and to analyse evaluate sensory acceptance of lamb burgers produced with the most promising natural antioxidants replacing sodium erythorbate. Plant extracts were evaluated regarding TEAC by DPPH(•) and FRAP methods, and total phenolics contents by Folin-Ciocalteau assay. The TEAC values ranged from 0.50 to 9.06 g trolox/100 g dry weight (dw) and from 43.6 to 472.32 μmol trolox/g dw for DPPH(•) and FRAP methods, respectively, and the total phenolic contents from 5.98 to 74.01 mg GAE/g dw. Extracts from Origanum vulgare, Melissa officinalis, Origanum majorana L. and Rosmarinus officinalis were grouped as the ones with higher antioxidant capacities by cluster analysis. All burgers produced with each one of these four plant extracts or with sodium erythorbate showed no differences (P > 0.05) regarding consumers' sensory acceptance. In conclusion, it is possible to replace sodium erythorbate in lamb burgers by any of the four natural extracts selected without compromising sensory acceptance of this meat product.

  14. Electronic plants.

    Science.gov (United States)

    Stavrinidou, Eleni; Gabrielsson, Roger; Gomez, Eliot; Crispin, Xavier; Nilsson, Ove; Simon, Daniel T; Berggren, Magnus

    2015-11-01

    The roots, stems, leaves, and vascular circuitry of higher plants are responsible for conveying the chemical signals that regulate growth and functions. From a certain perspective, these features are analogous to the contacts, interconnections, devices, and wires of discrete and integrated electronic circuits. Although many attempts have been made to augment plant function with electroactive materials, plants' "circuitry" has never been directly merged with electronics. We report analog and digital organic electronic circuits and devices manufactured in living plants. The four key components of a circuit have been achieved using the xylem, leaves, veins, and signals of the plant as the template and integral part of the circuit elements and functions. With integrated and distributed electronics in plants, one can envisage a range of applications including precision recording and regulation of physiology, energy harvesting from photosynthesis, and alternatives to genetic modification for plant optimization.

  15. The eln3 gene involved in fruiting body morphogenesis of Coprinus cinereus encodes a putative membrane protein with a general glycosyltransferase domain.

    Science.gov (United States)

    Arima, Toshihide; Yamamoto, Maki; Hirata, Aiko; Kawano, Shigeyuki; Kamada, Takashi

    2004-08-01

    We identified and characterized elongationless3 (eln3-1), a restriction enzyme-mediated integration (REMI) mutation affecting fruiting body morphogenesis in Coprinus cinereus. The mutant produces an aberrant fruiting body in which the stipe hardly elongates during fruiting body maturation. In the wild type, cylindrical stipe cells, elongation growth of which is responsible for stipe elongation, make side-by-side contact with one another and run parallel to the stipe axis, whereas in the mutant, the organization of the stipe tissue is disturbed and much space is produced between stipe cells. This disorganization of the stipe tissue, together with reduced elongation of the stipe cells, causes the mutant stipe short and bulgy. After a plasmid rescue, the eln3 gene was identified as a DNA fragment that complements the eln3-1 mutation. The eln3 ORF is predicted to encode a protein of 927 amino acids with a general glycosyltransferase domain and to be located in the plasma membrane. Transcription of the eln3 gene is specifically activated in rapidly elongating stipes. Possible involvement of the putative Eln3 enzyme in cell-to-cell connection is discussed.

  16. Production of γ-cyclodextrin by Bacillus cereus cyclodextrin glycosyltransferase using extractive bioconversion in polymer-salt aqueous two-phase system.

    Science.gov (United States)

    Lin, Yu Kiat; Show, Pau Loke; Yap, Yee Jiun; Ariff, Arbakariya B; Mohammad Annuar, Mohammad Suffian; Lai, Oi Ming; Tang, Teck Kim; Juan, Joon Ching; Ling, Tau Chuan

    2016-06-01

    Aqueous two-phase system (ATPS) extractive bioconversion provides a technique which integrates bioconversion and purification into a single step process. Extractive bioconversion of gamma-cyclodextrin (γ-CD) from soluble starch with cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) enzyme derived from Bacillus cereus was evaluated using polyethylene glycol (PEG)/potassium phosphate based on ATPS. The optimum condition was attained in the ATPS constituted of 30.0% (w/w) PEG 3000 g/mol and 7.0% (w/w) potassium phosphate. A γ-CD concentration of 1.60 mg/mL with a 19% concentration ratio was recovered after 1 h bioconversion process. The γ-CD was mainly partitioned to the top phase (YT=81.88%), with CGTase partitioning in the salt-rich bottom phase (KCGTase=0.51). Repetitive batch processes of extractive bioconversion were successfully recycled three times, indicating that this is an environmental friendly and a cost saving technique for γ-CD production and purification. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  17. Expression and Purification of Glycosyltransferases in Pichia Pastoris: Towards Improving the Migration of Stem Cells by Enhancing Surface Expression of Sialyl Lewis X

    KAUST Repository

    Al-Amoodi, Asma S.

    2017-05-01

    Recruitment of circulating cells towards target sites is primarily dependent on E-selectin receptor/ligand adhesive interactions. Glycosyltransferase (GTs) are involved in the creation of E-selectin ligands. A sialofucosylated terminal tetrasaccharide like glycan structure known as sialyl Lewis x (sLex), is the most recognized ligand by selectins. This structure is found on the surface of cancer cells and leukocytes but is often absent on the surface of many adult stem cell populations. In order to synthesize sLex, GTs must be endogenously expressed and remain active within the cells. Generally, these stem cells express terminal sialylated lactosamine structures on their glycoproteins which require the addition of alpha-(1,3)-fucose to be converted into an E-selectin ligand. There are a number of fucosyltransferases (FUTs) that are able to modify terminal lactosamine structures to create sLex such as FUT6. In this work we focused on expressing and purifying active recombinant FUTs as a tool to help create sLex structures on the surface of adult stem cells in order to enhance their migration.

  18. Cyclodextrin glycosyltransferase production by free cells of Bacillus circulans DF 9R in batch fermentation and by immobilized cells in a semi-continuous process.

    Science.gov (United States)

    Costa, Hernán; Gastón, Jorgelina Rodríguez; Lara, Julia; Martinez, Camila Ortiz; Moriwaki, Cristiane; Matioli, Graciette; Ferrarotti, Susana Alicia

    2015-06-01

    Cyclodextrin glycosyltransferase (CGTase) catalyzes starch conversion into cyclic or linear oligosaccharides, important industrial products for the complexation of non-polar substances. In this work, conditions to increase CGTase production from Bacillus circulans strain DF 9R were optimized by two systems. On one hand, free cells were grown in batch fermentation experiments to optimize aeration and pH. The highest activity (1.47 ± 0.21 U ml(-1)) was achieved after 48 h of growth, aeration of 1.5 vvm and pH regulated to 7.6. On the other hand, bacterial cells were immobilized on loofa and synthetic sponge, and used for CGTase production in a semi-continuous process. An initial biomass of 30 mg of lyophilized cells and an immobilization time of 24 h with loofa or synthetic sponge were enough to achieve increased production of CGTase: 0.91 ± 0.10 and 0.95 ± 0.11 U ml(-1), respectively. Sponges with immobilized bacteria were reused in 12 successive cycles. Besides, in our conditions, CGTase was not adsorbed onto the supports used for immobilization, which ensured the total recovery of the enzyme from the culture medium. The two CGTase production processes studied showed similar productivity and could be potentially scaled up.

  19. Glyco-engineering of biotherapeutic proteins in plants.

    Science.gov (United States)

    Ko, Kisung; Ahn, Mi-Hyun; Song, Mira; Choo, Young-Kug; Kim, Hyun Soon; Ko, Kinarm; Joung, Hyouk

    2008-06-30

    Many therapeutic glycoproteins have been successfully generated in plants. Plants have advantages regarding practical and economic concerns, and safety of protein production over other existing systems. However, plants are not ideal expression systems for the production of biopharmaceutical proteins, due to the fact that they are incapable of the authentic human N-glycosylation process. The majority of therapeutic proteins are glycoproteins which harbor N-glycans, which are often essential for their stability, folding, and biological activity. Thus, several glyco-engineering strategies have emerged for the tailor-making of N-glycosylation in plants, including glycoprotein subcellular targeting, the inhibition of plant specific glycosyltranferases, or the addition of human specific glycosyltransferases. This article focuses on plant N-glycosylation structure, glycosylation variation in plant cell, plant expression system of glycoproteins, and impact of glycosylation on immunological function. Furthermore, plant glyco-engineering techniques currently being developed to overcome the limitations of plant expression systems in the production of therapeutic glycoproteins will be discussed in this review.

  20. Two UGT84 Family Glycosyltransferases Catalyze a Critical Reaction of Hydrolyzable Tannin Biosynthesis in Pomegranate (Punica granatum.

    Directory of Open Access Journals (Sweden)

    Nadia N Ono

    Full Text Available Hydrolyzable tannins (HTs play important roles in plant herbivore deterrence and promotion of human health. A critical step in HT production is the formation of 1-O-galloyl-β-D-glucopyranoside (β-glucogallin, ester-linked gallic acid and glucose by a UDP-glucosyltransferase (UGT activity. We cloned and biochemically characterized four candidate UGTs from pomegranate (Punica granatum, of which only UGT84A23 and UGT84A24 exhibited β-glucogallin forming activities in enzyme assays. Although overexpression and single RNAi knockdown pomegranate hairy root lines of UGT84A23 or UGT84A24 did not lead to obvious alterations in punicalagin (the prevalent HT in pomegranate accumulation, double knockdown lines of the two UGTs resulted in largely reduced levels of punicalagins and bis-hexahydroxydiphenyl glucose isomers. An unexpected accumulation of galloyl glucosides (ether-linked gallic acid and glucose was also detected in the double knockdown lines, suggesting that gallic acid was utilized by an unidentified UGT activity for glucoside formation. Transient expression in Nicotiana benthamiana leaves and immunogold labeling in roots of pomegranate seedlings collectively indicated cytosolic localization of UGT84A23 and UGT84A24. Overall, functional characterization and localization of UGT84A23 and UGT84A24 open up opportunities for further understanding the regulatory control of HT metabolism in plants and its coordination with other biochemical pathways in the metabolic network.

  1. Two UGT84 Family Glycosyltransferases Catalyze a Critical Reaction of Hydrolyzable Tannin Biosynthesis in Pomegranate (Punica granatum).

    Science.gov (United States)

    Ono, Nadia N; Qin, Xiaoqiong; Wilson, Alexander E; Li, Gang; Tian, Li

    2016-01-01

    Hydrolyzable tannins (HTs) play important roles in plant herbivore deterrence and promotion of human health. A critical step in HT production is the formation of 1-O-galloyl-β-D-glucopyranoside (β-glucogallin, ester-linked gallic acid and glucose) by a UDP-glucosyltransferase (UGT) activity. We cloned and biochemically characterized four candidate UGTs from pomegranate (Punica granatum), of which only UGT84A23 and UGT84A24 exhibited β-glucogallin forming activities in enzyme assays. Although overexpression and single RNAi knockdown pomegranate hairy root lines of UGT84A23 or UGT84A24 did not lead to obvious alterations in punicalagin (the prevalent HT in pomegranate) accumulation, double knockdown lines of the two UGTs resulted in largely reduced levels of punicalagins and bis-hexahydroxydiphenyl glucose isomers. An unexpected accumulation of galloyl glucosides (ether-linked gallic acid and glucose) was also detected in the double knockdown lines, suggesting that gallic acid was utilized by an unidentified UGT activity for glucoside formation. Transient expression in Nicotiana benthamiana leaves and immunogold labeling in roots of pomegranate seedlings collectively indicated cytosolic localization of UGT84A23 and UGT84A24. Overall, functional characterization and localization of UGT84A23 and UGT84A24 open up opportunities for further understanding the regulatory control of HT metabolism in plants and its coordination with other biochemical pathways in the metabolic network.

  2. Identification of UDP-glycosyltransferases involved in the biosynthesis of astringent taste compounds in tea (Camellia sinensis).

    Science.gov (United States)

    Cui, Lilan; Yao, Shengbo; Dai, Xinlong; Yin, Qinggang; Liu, Yajun; Jiang, Xiaolan; Wu, Yahui; Qian, Yumei; Pang, Yongzhen; Gao, Liping; Xia, Tao

    2016-04-01

    Galloylated catechins and flavonol 3-O-glycosides are characteristic astringent taste compounds in tea (Camellia sinensis). The mechanism involved in the formation of these metabolites remains unknown in tea plants. In this paper, 178 UGT genes (CsUGTs) were identified inC. sinensis based on an analysis of tea transcriptome data. Phylogenetic analysis revealed that 132 of these genes were clustered into 15 previously established phylogenetic groups (A to M, O and P) and a newly identified group R. Three of the 11 recombinant UGT proteins tested were found to be involved in the in vitro biosynthesis of β-glucogallin and glycosylated flavonols. CsUGT84A22 exhibited catalytic activity toward phenolic acids, in particular gallic acid, to produce β-glucogallin, which is the immediate precursor of galloylated catechin biosynthesis in tea plants. CsUGT78A14 and CsUGT78A15 were found to be responsible for the biosynthesis of flavonol 3-O-glucosides and flavonol 3-O-galactosides, respectively. Site-directed mutagenesis of the Q373H substitution for CsUGT78A14 indicated that the Q (Gln) residue played a catalytically crucial role for flavonoid 3-O-glucosyltransferase activity. The expression profiles of the CsUGT84A22, CsUGT78A14, and CsUGT78A15 genes were correlated with the accumulation patterns of β-glucogallin and the glycosylated flavonols which indicated that these three CsUGT genes were involved in the biosynthesis of astringent compounds inC. sinensis. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  3. Immune responses and protection against experimental challenge after vaccination of bison with Brucella abortus strain RB51 or RB51 overexpressing superoxide dismutase and glycosyltransferase genes.

    Science.gov (United States)

    Olsen, S C; Boyle, S M; Schurig, G G; Sriranganathan, N N

    2009-04-01

    Vaccination is a tool that could be beneficial in managing the high prevalence of brucellosis in free-ranging bison in Yellowstone National Park. In this study, we characterized immunologic responses and protection against experimental challenge after vaccination of bison with Brucella abortus strain RB51 (RB51) or a recombinant RB51 strain overexpressing superoxide dismutase (sodC) and glycosyltransferase (wboA) genes (RB51+sodC,wboA). Bison were vaccinated with saline only or with 4.6 x 10(10) CFU of RB51 or 7.4 x 10(10) CFU of RB51+sodC,wboA (n = eight animals/treatment). Bison vaccinated with RB51 or RB51+sodC,wboA had greater (P RB51 after vaccination than did nonvaccinates. However, bison vaccinated with RB51+sodC,wboA cleared the vaccine strain from draining lymph nodes faster than bison vaccinated with the parental RB51 strain. Immunologic responses of bison vaccinated with RB51+sodC,wboA were similar to responses of bison vaccinated with RB51. Pregnant bison were intraconjunctivally challenged in midgestation with 10(7) CFU of B. abortus strain 2308. Bison vaccinated with RB51, but not RB51+sodC,wboA vaccinates, had greater protection from abortion, fetal/uterine, mammary, or maternal infection than nonvaccinates. Our data suggest that the RB51+sodC,wboA strain is less efficacious as a calfhood vaccine for bison than the parental RB51 strain. Our data also suggest that the RB51 vaccine is a currently available management tool that could be utilized to help reduce brucellosis in free-ranging bison.

  4. Plant Research '75

    Energy Technology Data Exchange (ETDEWEB)

    1975-01-01

    Research is reported on stomatal regulation of the gas exchanges between plant and environment; inhibitory effects in flower formation; plant growth and development through hormones; hormone action; development and nitrogen fixation in algae; primary cell wall glycoprotein ectensin; enzymic mechanisms and control of polysaccharide and glycoprotein synthesis; molecular studies of membrane studies; sensory transduction in plants; regulation of formation of protein complexes and enzymes in higher plant cell and mechanism of sulfur dioxide toxicity in plants. (PCS)

  5. Evaluation of antioxidant capacity of 13 plant extracts by three different methods: cluster analyses applied for selection of the natural extracts with higher antioxidant capacity to replace synthetic antioxidant in lamb burgers

    OpenAIRE

    Fernandes, R. P. P.; Trindade, M. A.; Tonin, F. G.; LIMA, C.G. de; Pugine, S. M. P.; Munekata, P. E. S.; Lorenzo, J.M.; M.P. Melo

    2015-01-01

    The aims of this study were: to evaluate the total equivalent antioxidant capacities (TEAC) and phenolic contents of 13 plants extracts; to select the most promising extracts regarding reducing activity using cluster analysis multivariate statistical technique; and to analyse evaluate sensory acceptance of lamb burgers produced with the most promising natural antioxidants replacing sodium erythorbate. Plant extracts were evaluated regarding TEAC by DPPH• and FRAP methods, and total phenolics ...

  6. Root uptake of uranium (6) in solution by a higher plant: speciation in hydroponic solution, bioavailability, micro-localisation and biological effects induced; Transfert racinaire de l'uranium (6) en solution chez une plante superieure: speciation en solution hydroponique, prise en charge par la plante, microlocalisation et effets biologiques induits

    Energy Technology Data Exchange (ETDEWEB)

    Laroche, L

    2005-01-15

    Uranium exists naturally in the environment, usually present in trace quantities. In soil solution and oxic conditions, uranium is present in the +VI oxidation state and forms a large number of inorganic and organic complexes. The exposure medium, an artificial soil solution, was designed in such a way as to control the uranium species in solution. The geochemical speciation code JCHESS was used to calculate the uranium aqueous species concentration and to define the domains of interest, each of them characterized by a limited number of dominant U species. These domains were defined as follows: pH 4.9 with uranyl ions as dominant species, pH 5.8 with hydroxyl complexes and pH 7 where carbonates play a major role. For each pH, short-duration (5 hours of exposure) well-defined laboratory experiments were carried out with Phaseolus vulgaris as plant model. The effect of competitive ions such as Ca{sup 2+} or the presence of ligands such as phosphate or citrate on root assimilation efficiency was explored. Results have shown that uranium transfer was not affected by the presence of calcium, phosphate or citrate (but was decreased of 60% with citrate (10 {mu}M) at pH 5.8) in our experimental conditions. Moreover, observation in Transmission Electronic Microscopy (TEM), equipped with an EDAX probe, have shown that uranium was associated with granules rich in phosphorus and that there were some chloroplast anomalies. Finally, the presence of uranium affects root CEC by reducing it and stimulates root elongation at low uranium concentrations (100 nM, 400 nM and 2 {mu}M at pHs 4.9, 5.8 and 7 respectively) and inhibits it at high uranium concentrations. (author)

  7. Epigenetic performers in plants.

    Science.gov (United States)

    Chen, Ming; Lv, Shaolei; Meng, Yijun

    2010-08-01

    Epigenetic research is at the forefront of plant biology and molecular genetics. Studies on higher plants underscore the significant role played by epigenetics in both plant development and stress response. Relatively recent advances in analytical methodology have allowed for a significant expansion of what is known about genome-wide mapping of DNA methylation and histone modifications. In this review, we explore the different modification patterns in plant epigenetics, and the key factors involved in the epigenetic process, in order to illustrate various putative mechanisms. Experimental technology to exploit these modifications, and proposed focus areas for future plant epigenetic research, are also presented.

  8. The impact of pCO2 and climate on D/H and 13C/12C fractionation of higher-plant biomarkers: Implications for paleoclimate and paleoelevation reconstruction during global warm periods

    Science.gov (United States)

    Hren, M. T.; Tipple, B. J.; Pagani, M.

    2012-12-01

    Stable hydrogen isotope compositions (D/H) of plant biomarkers record the hydrogen isotopic composition of leaf water at the time of plant growth. However, the magnitude of the apparent hydrogen isotope fractionation between biomarkers and precipitation can vary due to soil- or leaf-water evaporation or differing water-use strategies. As a result, climate-induced changes in soil- or leaf-water evaporation rates and/or changes in plant assemblages during periods of global warming and high atmospheric CO2 could impact apparent carbon and hydrogen isotope fractionations. We measured hydrogen and carbon isotope ratios of long-carbon chain n-alkanes from modern and ~50 million year old fossil leaves preserved in paleo-Sierra Nevada riverine sediments to determine how climate and ecosystem differences during a period of extremely high pCO2 impact the magnitude and variability of D/H and 13C/12C ratios of leaf-waxes across a topographic gradient. δDalkanes (nC27 to nC31) of individual fossil and modern leaves decrease systematically across the topographic gradient and follow the change in the D/H of precipitation due to orographic lifting and continuous rainout. Using estimated values of Eocene δDprecip at the Pacific margin (-43 to -61‰), apparent fractionations (ɛalkane - precip) for Eocene angiosperm trees are similar to that seen for modern, humid environments (~ -106 to -124‰ ±10‰ 1σ), and more negative than observed in modern sun-exposed leaves in the Sierra Nevada (-96 to -102‰) or soils (-87 to -92‰). Single site variability in leaf-wax δD from individual fossil angiosperms can exceed 20‰, but is considerably smaller than observed for modern, mixed angiosperm/gymnosperm forests of the seasonally dry Sierra Nevada range. δ13Calkane values show little or no systematic variation across the range. However, carbon isotope discrimination in ancient and modern leaves is similar, suggesting strong climatic and weak pCO2 controls on D/H and 13C/12C

  9. The carbon fertilization effect over a century of anthropogenic CO2 emissions: higher intracellular CO2 and more drought resistance among invasive and native grass species contrasts with increased water use efficiency for woody plants in the US Southwest.

    Science.gov (United States)

    Drake, Brandon L; Hanson, David T; Lowrey, Timothy K; Sharp, Zachary D

    2017-02-01

    From 1890 to 2015, anthropogenic carbon dioxide emissions have increased atmospheric CO2 concentrations from 270 to 400 mol mol(-1) . The effect of increased carbon emissions on plant growth and reproduction has been the subject of study of free-air CO2 enrichment (FACE) experiments. These experiments have found (i) an increase in internal CO2 partial pressure (ci ) alongside acclimation of photosynthetic capacity, (ii) variable decreases in stomatal conductance, and (iii) that increases in yield do not increase commensurate with CO2 concentrations. Our data set, which includes a 115-year-long selection of grasses collected in New Mexico since 1892, is consistent with an increased ci as a response to historical CO2 increase in the atmosphere, with invasive species showing the largest increase. Comparison with Palmer Drought Sensitivity Index (PDSI) for New Mexico indicates a moderate correlation with Δ(13) C (r(2)  = 0.32, P CO2 in the event of reduced stomatal conductance in response to short-term water shortage. Comparison with C3 trees from arid environments (Pinus longaeva and Pinus edulis in the US Southwest) as well as from wetter environments (Bromus and Poa grasses in New Mexico) suggests differing responses based on environment; arid environments in New Mexico see increased intrinsic water use efficiency (WUE) in response to historic elevated CO2 while wetter environments see increased ci . This study suggests that (i) the observed increases in ci in FACE experiments are consistent with historical CO2 increases and (ii) the CO2 increase influences plant sensitivity to water shortage, through either increased WUE or ci in arid and wet environments, respectively. © 2016 John Wiley & Sons Ltd.

  10. Overexpression of WsSGTL1 gene of Withania somnifera enhances salt tolerance, heat tolerance and cold acclimation ability in transgenic Arabidopsis plants.

    Directory of Open Access Journals (Sweden)

    Manoj K Mishra

    Full Text Available BACKGROUND: Sterol glycosyltrnasferases (SGT are enzymes that glycosylate sterols which play important role in plant adaptation to stress and are medicinally important in plants like Withania somnifera. The present study aims to find the role of WsSGTL1 which is a sterol glycosyltransferase from W. somnifera, in plant's adaptation to abiotic stress. METHODOLOGY: The WsSGTL1 gene was transformed in Arabidopsis thaliana through Agrobacterium mediated transformation, using the binary vector pBI121, by floral dip method. The phenotypic and physiological parameters like germination, root length, shoot weight, relative electrolyte conductivity, MDA content, SOD levels, relative electrolyte leakage and chlorophyll measurements were compared between transgenic and wild type Arabidopsis plants under different abiotic stresses--salt, heat and cold. Biochemical analysis was done by HPLC-TLC and radiolabelled enzyme assay. The promoter of the WsSGTL1 gene was cloned by using Genome Walker kit (Clontech, USA and the 3D structures were predicted by using Discovery Studio Ver. 2.5. RESULTS: The WsSGTL1 transgenic plants were confirmed to be single copy by Southern and homozygous by segregation analysis. As compared to WT, the transgenic plants showed better germination, salt tolerance, heat and cold tolerance. The level of the transgene WsSGTL1 was elevated in heat, cold and salt stress along with other marker genes such as HSP70, HSP90, RD29, SOS3 and LEA4-5. Biochemical analysis showed the formation of sterol glycosides and increase in enzyme activity. When the promoter of WsSGTL1 gene was cloned from W. somnifera and sequenced, it contained stress responsive elements. Bioinformatics analysis of the 3D structure of the WsSGTL1 protein showed functional similarity with sterol glycosyltransferase AtSGT of A. thaliana. CONCLUSIONS: Transformation of WsSGTL1 gene in A. thaliana conferred abiotic stress tolerance. The promoter of the gene in W.somnifera was found

  11. Secondary Metabolites from Higher Fungi.

    Science.gov (United States)

    Chen, He-Ping; Liu, Ji-Kai

    Secondary metabolites of higher fungi (mushrooms) are an underexplored resource compared to plant-derived secondary metabolites. An increasing interest in mushroom natural products has been noted in recent years. This chapter gives a comprehensive overview of the secondary metabolites from higher fungi, with 765 references highlighting the isolation, structure elucidation, biological activities, chemical syntheses, and biosynthesis of pigments, nitrogen-containing compounds, and terpenoids from mushrooms. Mushroom toxins are also included in each section.In a section on pigments of higher fungi, pigments are classified into four categories, namely, those from the shikimate-chorismate, acetate-malonate, and mevalonate biosynthetic pathways, and pigments containing nitrogen, with 145 references covering the years 2010-2016.In a section on other nitrogen-containing compounds of higher fungi, compounds are categorized primarily into nitrogen heterocycles, nucleosides, non-protein amino acids, cyclic peptides, and sphingolipids, with 65 references covering the years 2010-2016. In turn, in a section describing terpenoids of higher fungi, the sesquiterpenoids and diterpenoids are thoroughly elaborated, spanning the years 2001-2016, and 2009-2016, respectively. The divergent biosynthetic pathways from farnesyl pyrophosphate to sesquiterpenoids are also described. Selected triterpenoids with novel structures and promising biological activities, including lanostanes and ergostanes, are reported from the genus Ganoderma, and the fungi Antrodia cinnamomea and Poria cocos. In addition, cucurbitanes and saponaceolides are also compiled in this section.

  12. Multinationals and plant survival

    DEFF Research Database (Denmark)

    Bandick, Roger

    2010-01-01

    The aim of this paper is twofold: first, to investigate how different ownership structures affect plant survival, and second, to analyze how the presence of foreign multinational enterprises (MNEs) affects domestic plants’ survival. Using a unique and detailed data set on the Swedish manufacturing...... sector, I am able to separate plants into those owned by foreign MNEs, domestic MNEs, exporting non-MNEs, and purely domestic firms. In line with previous findings, the result, when conditioned on other factors affecting survival, shows that foreign MNE plants have lower survival rates than non......-MNE plants. However, separating the non-MNEs into exporters and non-exporters, the result shows that foreign MNE plants have higher survival rates than non-exporting non-MNEs, while the survival rates of foreign MNE plants and exporting non-MNE plants do not seem to differ. Moreover, the simple non...

  13. Globalisation and Higher Education

    NARCIS (Netherlands)

    Marginson, Simon; van der Wende, Marijk

    2007-01-01

    Economic and cultural globalisation has ushered in a new era in higher education. Higher education was always more internationally open than most sectors because of its immersion in knowledge, which never showed much respect for juridical boundaries. In global knowledge economies, higher education

  14. India's Higher Education Challenges

    Science.gov (United States)

    Altbach, Philip G.

    2014-01-01

    India, with the world's second largest higher education system and a rapidly growing economy as one of the BRIC nations, faces significant challenges in building both capacity and excellence in higher education. India's higher education system is characterized by "islands of excellence in a sea of mediocrity." The mainstream universities…

  15. 5 prime -Azido-(3,6- sup 3 H sub 2 )-1-naphthylphthalamic acid, a photoactivatable probe for naphthylphthalamic acid receptor proteins from higher plants: Identification of a 23-kDa protein from maize coleoptile plasma membranes

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, R.; Feldwisch, J.; Schell, J.; Palme, K. (Max-Planck-Inst. fuer Zuechtungsforschung, Koeln (West Germany)); Boland, W. (Univ. Karlsruhe (West Germany))

    1992-01-15

    1-Naphthylphthalamic acid (NPA) is a specific inhibitor of polar auxin transport that blocks carrier mediated auxin efflux from plant cells. To allow identification of the NPA receptor thought to be part of the auxin efflux carrier, the authors have synthesized a tritiated, photolabile NPA analogue, 5{prime}-azido-(3,6-{sup 3}H{sub 2})NPA (({sup 3}H{sub 2})N{sub 3}NPA). This analogue was used to identify NPA-binding proteins in fractions highly enriched for plasma membrane vesicles isolated from maize coleoptiles (Zea mays L.). Competition studies showed that binding of ({sup 3}H{sub 2})N{sub 3}NPA to maize plasma membrane vesicles was blocked by nonradioactive NPA but not by benzoic acid. After incubation of plasma membrane vesicles with ({sup 3}H{sub 2})N{sub 3}NPA and exposure to UV light, they observed specific photoaffinity labeling of a protein with an apparent molecular mass of 23 kDa. Pretreatment of the plasma membrane vesicles with indole-3-acetic acid or with the auxin-transport inhibitors NPA and 2,3,5-triiodobenzoic acid strongly reduced specific labeling of this protein. This 23-kDa protein was also labeled by addition of 5-azido-(7-{sup 3}H)indole-3-acetic acid to plasma membranes prior to exposure to UV light. The 23-kDa protein was solubilized from plasma membranes by 1% Triton X-100. The possibility that this 23-kDa polypeptide is part of the auxin efflux carrier system is discussed.

  16. [Higher Brain Dysfunction].

    Science.gov (United States)

    Kashima, Haruo

    2015-01-01

    The technical term "higher brain dysfunction" is used widely in Japan. However, it is not always clear what "higher" means. The author thinks that the term "higher" is understood as being associated with a meaning. In this article, the differences between higher brain dysfunctions and elementary brain dysfunctions are discussed from the point of view of lesion localization and the consistency of symptoms. The psychiatric approach is indispensable for the assessment of higher brain dysfunction. A simple test for mild Alzheimer-type dementia is also introduced.

  17. Relation between higher heating value and elemental and mineral biomass plant components Relação entre o poder calorífico superior e os componentes elementares e minerais da biomassa vegetal

    Directory of Open Access Journals (Sweden)

    Thiago de Paula Protásio

    2011-06-01

    Full Text Available

    The aims of this work were to evaluate the correlation, to adjust and select simple and multiple linear statistical models between elemental components (carbon, hydrogen and oxygen and ash content with higher heating value for plant biomass; to use the principle components analysis for the creation of an energetic development index and to adjust a linear model between energetic development index and higher heating value. Eight types of biomass were used. Three linear and nine multiple statistical models were adjusted. The best models were selected based on the significance of coefficients, adjusted determination coefficient, estimative standard error, coefficient of variation, linearity of parameters, normality, presence of heterocedasticity and lack of error correlation. The variance inflation factor was determined for linear multiple models. High correlation between the variables studied was found. Models 1, 3 and 11 were considered most adequate. Practical use of model 2 is not possible. Principle components analysis was efficient in obtaining an energetic development index of lignocellulosic residues and it may be used for solving multicollinearity found between variables considered.

    doi: 10.4336/2011.pfb.31.66.113

    Os objetivos do trabalho foram avaliar a correlação, ajustar e selecionar modelos estatísticos lineares simples e múltiplos entre os componentes elementares (carbono, hidrogênio e oxigênio e o teor de cinzas com o poder calorífico superior da biomassa vegetal; utilizar a análise de componentes principais para a criação de um índice de desempenho energético e ajustar um modelo linear entre o índice de desempenho energético e o poder calorífico superior. Utilizaram-se oito tipos de biomassa. Foram ajustadas equações referentes a três modelos estatísticos lineares simples e nove múltiplos. Os melhores modelos foram selecionados com base na significância dos seus coeficientes, no coeficiente de

  18. Uptake and metabolism of diclofenac in Typha latifolia--how plants cope with human pharmaceutical pollution.

    Science.gov (United States)

    Bartha, Bernadett; Huber, Christian; Schröder, Peter

    2014-10-01

    The fate of pharmaceuticals in our environment is a very important issue for environmental and health research. Although these substances have been detected in environmental compartments in low concentration until now, they will pose considerable environmental risk to ecosystems, animals and human due to their biological activity. Alternative plant based removal technologies that make use of some potential wetland species like Phragmites or Typha within traditional wastewater treatment plants have to be established to cope with this "new generation" of pollutants. We investigated uptake and translocation of diclofenac (1mgl(-1)) in the macrophyte Typha latifolia L. during one week exposure in greenhouse experiments. Detoxification products and involved key enzymatic processes were identified. We also examined the oxidative stress induced by the treatment and the defense capacity of the plants. Rapid uptake and effective metabolism were observed, where glycoside and glutathione conjugates represent dominant metabolites. Up to seven-fold induction of glycosyltransferase activity was observed in roots, but not in shoots. Glutathione S-transferase activity was also induced, but to a lower extent. The activity changes of defense enzymes points to oxidative stress in the plants. Our results show that human pharmaceuticals can be metabolized by plants similar to xenobiotics, but that similarities to human metabolism are limited. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  19. Higher derivative mimetic gravity

    Science.gov (United States)

    Gorji, Mohammad Ali; Mansoori, Seyed Ali Hosseini; Firouzjahi, Hassan

    2018-01-01

    We study cosmological perturbations in mimetic gravity in the presence of classified higher derivative terms which can make the mimetic perturbations stable. We show that the quadratic higher derivative terms which are independent of curvature and the cubic higher derivative terms which come from curvature corrections are sufficient to remove instabilities in mimetic perturbations. The classified higher derivative terms have the same dimensions but they contribute differently in the background and perturbed equations. Therefore, we can control both the background and the perturbation equations allowing us to construct the higher derivative extension of mimetic dark matter and the mimetic nonsingular bouncing scenarios. The latter can be thought as a new higher derivative effective action for the loop quantum cosmology scenario in which the equations of motion coincide with those suggested by loop quantum cosmology. We investigate a possible connection between the mimetic cosmology and the Randall-Sundrum cosmology.

  20. Higher Spin Matrix Models

    Directory of Open Access Journals (Sweden)

    Mauricio Valenzuela

    2017-10-01

    Full Text Available We propose a hybrid class of theories for higher spin gravity and matrix models, i.e., which handle simultaneously higher spin gravity fields and matrix models. The construction is similar to Vasiliev’s higher spin gravity, but part of the equations of motion are provided by the action principle of a matrix model. In particular, we construct a higher spin (gravity matrix model related to type IIB matrix models/string theory that have a well defined classical limit, and which is compatible with higher spin gravity in A d S space. As it has been suggested that higher spin gravity should be related to string theory in a high energy (tensionless regime, and, therefore to M-Theory, we expect that our construction will be useful to explore concrete connections.

  1. Considering Plants.

    Science.gov (United States)

    Flannery, Maura C.

    1991-01-01

    Examples from research that incorporate plants to illustrate biological principles are presented. Topics include dried pea shape, homeotic genes, gene transcription in plants that are touched or wounded, production of grasslands, seaweed defenses, migrating plants, camouflage, and family rivalry. (KR)

  2. Higher dimensional higher derivative ϕ4 theory

    Science.gov (United States)

    Gracey, J. A.; Simms, R. M.

    2017-07-01

    We construct several towers of scalar quantum field theories with an O (N ) symmetry which have higher derivative kinetic terms. The Lagrangians in each tower are connected by lying in the same universality class at the d -dimensional Wilson-Fisher fixed point. Moreover the universal theory is studied using the large N expansion and we determine d -dimensional critical exponents to O (1 /N2). We show that these new universality classes emerge naturally as solutions to the linear relation of the dimensions of the fields deduced from the underlying force-matter interaction of the universal critical theory. To substantiate the equivalence of the Lagrangians in each tower we renormalize each to several loop orders and show that the renormalization group functions are consistent with the large N critical exponents. While we focus on the first two new towers of theories and renormalize the respective Lagrangians to 16 and 18 dimensions there are an infinite number of such towers. We also briefly discuss the conformal windows and the extension of the ideas to theories with spin-1/2 and spin-1 fields as well as the idea of lower dimension completeness.

  3. Cost in Higher Education

    Science.gov (United States)

    2007-06-01

    standardize methodology and accountability used nationwide by institutions of higher education . The aim is to review existing cost criteria and procedures...task. The objective of this research is to look into the cost structure used presently by two institutions of higher education , namely the Naval

  4. Higher Education in California

    Science.gov (United States)

    Public Policy Institute of California, 2016

    2016-01-01

    Higher education enhances Californians' lives and contributes to the state's economic growth. But population and education trends suggest that California is facing a large shortfall of college graduates. Addressing this short­fall will require strong gains for groups that have been historically under­represented in higher education. Substantial…

  5. Reputation in Higher Education

    DEFF Research Database (Denmark)

    Plewa, Carolin; Ho, Joanne; Conduit, Jodie

    2016-01-01

    Reputation is critical for institutions wishing to attract and retain students in today's competitive higher education setting. Drawing on the resource based view and configuration theory, this research proposes that Higher Education Institutions (HEIs) need to understand not only the impact...

  6. Happiness in Higher Education

    Science.gov (United States)

    Elwick, Alex; Cannizzaro, Sara

    2017-01-01

    This paper investigates the higher education literature surrounding happiness and related notions: satisfaction, despair, flourishing and well-being. It finds that there is a real dearth of literature relating to profound happiness in higher education: much of the literature using the terms happiness and satisfaction interchangeably as if one were…

  7. Reimagining Christian Higher Education

    Science.gov (United States)

    Hulme, E. Eileen; Groom, David E., Jr.; Heltzel, Joseph M.

    2016-01-01

    The challenges facing higher education continue to mount. The shifting of the U.S. ethnic and racial demographics, the proliferation of advanced digital technologies and data, and the move from traditional degrees to continuous learning platforms have created an unstable environment to which Christian higher education must adapt in order to remain…

  8. Consumerism in Higher Education

    Science.gov (United States)

    Green, Mark

    1973-01-01

    In considering consumerism in higher education, the student becomes the consumer,'' the university the corporation,'' and higher education the education industry.'' Other members of the education fraternity become investors, management, workers, direct consumers, and indirect consumers. This article proposes that it behooves the student to…

  9. Quality of Higher Education

    DEFF Research Database (Denmark)

    Zou, Yihuan

    is about constructing a more inclusive understanding of quality in higher education through combining the macro, meso and micro levels, i.e. from the perspectives of national policy, higher education institutions as organizations in society, individual teaching staff and students. It covers both......Quality in higher education was not invented in recent decades – universities have always possessed mechanisms for assuring the quality of their work. The rising concern over quality is closely related to the changes in higher education and its social context. Among others, the most conspicuous...... changes are the massive expansion, diversification and increased cost in higher education, and new mechanisms of accountability initiated by the state. With these changes the traditional internally enacted academic quality-keeping has been given an important external dimension – quality assurance, which...

  10. Identification and deletion of Tft1, a predicted glycosyltransferase necessary for cell wall β-1,3;1,4-glucan synthesis in Aspergillus fumigatus.

    Directory of Open Access Journals (Sweden)

    Danial Samar

    Full Text Available Aspergillus fumigatus is an environmental mold that causes severe, often fatal invasive infections in immunocompromised patients. The search for new antifungal drug targets is critical, and the synthesis of the cell wall represents a potential area to find such a target. Embedded within the main β-1,3-glucan core of the A. fumigatus cell wall is a mixed linkage, β-D-(1,3;1,4-glucan. The role of this molecule or how it is synthesized is unknown, though it comprises 10% of the glucans within the wall. While this is not a well-studied molecule in fungi, it has been studied in plants. Using the sequences of two plant mixed linkage glucan synthases, a single ortholog was identified in A. fumigatus (Tft1. A strain lacking this enzyme (tft1Δ was generated along with revertant strains containing the native gene under the control of either the native or a strongly expressing promoter. Immunofluorescence staining with an antibody against β-(1,3;1,4-glucan and biochemical quantification of this polysaccharide in the tft1Δ strain demonstrated complete loss of this molecule. Reintroduction of the gene into the knockout strain yielded reappearance in amounts that correlated with expected expression of the gene. The loss of Tft1 and mixed linkage glucan yielded no in vitro growth phenotype. However, there was a modest increase in virulence for the tft1Δ strain in a wax worm model. While the precise roles for β-(1,3;1,4-glucan within A. fumigatus cell wall are still uncertain, it is clear that Tft1 plays a pivotal role in the biosynthesis of this cell wall polysaccharide.

  11. Silicon alleviates the deleterious salt effect on tomato plant growth by improving plant water status.

    Science.gov (United States)

    Romero-Aranda, Mercedes R; Jurado, Oliva; Cuartero, Jesús

    2006-07-01

    In order to investigate the role of Si in alleviating the deleterious effects of salinity on tomato plant growth, the tomato cultivar Moneymaker was grown with 0 or 80mM NaCl combined with 0 and 2.5mM Si. Plant growth parameters, salt accumulation in plant tissues and plant water relations were analysed. Si treatment did not alter salt input into the plant or salt distribution between plant organs. There were non-significant differences in plant water uptake, but plant water content in salinised plants supplied with Si was 40% higher than in salinised plants that were not supplied with Si. Plants treated with NaCl alone showed a reduction in plant dry weight and total plant leaf area of 55% and 58%, respectively, while the reduction in plants treated with NaCl plus Si was only 31% and 22%, respectively. Leaf turgor potential and net photosynthesis rates were 42% and 20% higher in salinised plants supplied with Si than in salinised plants that were not supplied with Si. Water use efficiency calculated from instantaneous gas exchange parameters and as the ratio between plant dry matter and plant water uptake were, respectively, 17% and 16% higher in salinised plants supplied with Si. It can be concluded that Si improves the water storage within plant tissues, which allows a higher growth rate that, in turn, contributes to salt dilution into the plant, mitigating salt toxicity effects.

  12. Higher English for CFE

    CERN Document Server

    Bridges, Ann; Mitchell, John

    2015-01-01

    A brand new edition of the former Higher English: Close Reading , completely revised and updated for the new Higher element (Reading for Understanding, Analysis and Evaluation) - worth 30% of marks in the final exam!. We are working with SQA to secure endorsement for this title. Written by two highly experienced authors this book shows you how to practice for the Reading for Understanding, Analysis and Evaluation section of the new Higher English exam. This book introduces the terms and concepts that lie behind success and offers guidance on the interpretation of questions and targeting answer

  13. Unexpected distribution of CA19.9 and other type 1 chain Lewis antigens in normal and cancer tissues of colon and pancreas: Importance of the detection method and role of glycosyltransferase regulation.

    Science.gov (United States)

    Aronica, Adele; Avagliano, Laura; Caretti, Anna; Tosi, Delfina; Bulfamante, Gaetano Pietro; Trinchera, Marco

    2017-01-01

    CA19.9 antigen has been assumed as an abundant product of cancer cells, due to the reactivity found by immunohistochemical staining of cancer tissues with anti-CA19.9 antibody. Expression and biosynthesis of type 1 chain Lewis antigens in the colon and the pancreas were studied by immunodetection in tissue sections and lysates, quantification of glycosyltransferase transcripts, bisulfite sequencing, and chromatin immunoprecipitation assays. CA19.9 was poorly detectable in normal colon mucosa and almost undetectable in colon cancer, while it was easily detected in the pancreatic ducts, together with Lewis b antigen, under both normal and cancer conditions. B3GALT5 transcripts were down-regulated in colon cancer, while they remained expressed in pancreatic cancer. Even ST3GAL3 transcript appeared well expressed in the pancreas but poorly in the colon, irrespective of normal or cancer conditions. CpG islands flanking B3GALT5 native promoter presented an extremely low degree of methylation in pancreatic cancer with respect to colon cancer. In a DNA region about 1kb away from the B3GALT5 retroviral promoter, a stretch of CG dinucleotides presented a methylation pattern potentially associated with transcription. Such a DNA region and the transcription factor binding site provided overlapping results by chromatin immunoprecipitation assays, corroborating the hypothesis. CA19.9 appears as a physiological product whose synthesis strongly depends on the tissue specific and epigenetically-regulated expression of B3GALT5 and ST3GAL3. CA19.9 and other Lewis antigens acquire tumor marker properties in the pancreas due to mechanisms giving rise to reabsorption into vessels and elevation in circulating levels. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Reputation in Higher Education

    DEFF Research Database (Denmark)

    Martensen, Anne; Grønholdt, Lars

    2005-01-01

    The purpose of this paper is to develop a reputation model for higher education programmes, provide empirical evidence for the model and illustrate its application by using Copenhagen Business School (CBS) as the recurrent case. The developed model is a cause-and-effect model linking image...... for higher education reputation and which relations exist between the included determinants from a theoretical perspective. It is demonstrated how the model and measurement system may be a useful management tool for the improvement of the reputation of a higher education. In this way, the model can help...... leaders of higher education institutions to set strategic directions and support their decisions in an effort to create even better study programmes with a better reputation. Finally, managerial implications and directions for future research are discussed.Keywords: Reputation, image, corporate identity...

  15. Higher Education in Scandinavia

    DEFF Research Database (Denmark)

    Nielsen, Jørgen Lerche; Birch Andreasen, Lars

    2015-01-01

    Higher education systems around the world have been undergoing fundamental changes through the last 50 years from more narrow self-sustaining universities for the elite and into mass universities, where new groups of students have been recruited and the number of students enrolled has increased....... In this chapter we will examine how higher education systems in Scandinavia are developing in relation to these challenges. To what extent has the democratic tradition had an impact on the educational systems, and what possible futures can be envisioned? In the development of higher education in Scandinavia......, there are different perspectives on education at play. One perspective sees education as a “public good” that benefits society and therefore should be free and accessible for all students who qualify to be admitted. According to this perspective, one of the main purposes of higher education is to add value to all...

  16. Higher Spins & Strings

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    The conjectured relation between higher spin theories on anti de-Sitter (AdS) spaces and weakly coupled conformal field theories is reviewed. I shall then outline the evidence in favour of a concrete duality of this kind, relating a specific higher spin theory on AdS3 to a family of 2d minimal model CFTs. Finally, I shall explain how this relation fits into the framework of the familiar stringy AdS/CFT correspondence.

  17. INTERNATIONALIZATION IN HIGHER EDUCATION

    OpenAIRE

    Catalina Crisan-Mitra; Anca Borza

    2015-01-01

    Internationalization of higher education is one of the key trends of development. There are several approaches on how to achieve competitiveness and performance in higher education and international academic mobility; students’ exchange programs, partnerships are some of the aspects that can play a significant role in this process. This paper wants to point out the student’s perception regarding two main directions: one about the master students’ expectation regarding how an internationalized...

  18. Integrated Gasification SOFC Plant with a Steam Plant

    DEFF Research Database (Denmark)

    Rokni, Masoud; Pierobon, Leonardo

    2011-01-01

    A hybrid Solid Oxide Fuel Cell (SOFC) and Steam Turbine (ST) plant is integrated with a gasification plant. Wood chips are fed to the gasification plant to produce biogas and then this gas is fed into the anode side of a SOFC cycle to produce electricity and heat. The gases from the SOFC stacks...... enter into a burner to burn the rest of the fuel. The offgases after the burner are now used to generate steam in a Heat Recovery Steam Generator (HRSG). The generated steam is expanded in a ST to produce additional power. Thus a triple hybrid plant based on a gasification plant, a SOFC plant...... and a steam plant is presented and studied. The plant is called as IGSS (Integrated Gasification SOFC Steam plant). Different systems layouts are presented and investigated. Electrical efficiencies up to 56% are achieved which is considerably higher than the conventional integrated gasification combined...

  19. Fuel Class Higher Alcohols

    KAUST Repository

    Sarathy, Mani

    2016-08-17

    This chapter focuses on the production and combustion of alcohol fuels with four or more carbon atoms, which we classify as higher alcohols. It assesses the feasibility of utilizing various C4-C8 alcohols as fuels for internal combustion engines. Utilizing higher-molecular-weight alcohols as fuels requires careful analysis of their fuel properties. ASTM standards provide fuel property requirements for spark-ignition (SI) and compression-ignition (CI) engines such as the stability, lubricity, viscosity, and cold filter plugging point (CFPP) properties of blends of higher alcohols. Important combustion properties that are studied include laminar and turbulent flame speeds, flame blowout/extinction limits, ignition delay under various mixing conditions, and gas-phase and particulate emissions. The chapter focuses on the combustion of higher alcohols in reciprocating SI and CI engines and discusses higher alcohol performance in SI and CI engines. Finally, the chapter identifies the sources, production pathways, and technologies currently being pursued for production of some fuels, including n-butanol, iso-butanol, and n-octanol.

  20. Quality of Higher Education

    DEFF Research Database (Denmark)

    Zou, Yihuan; Zhao, Yingsheng; Du, Xiangyun

    . This transformation involves a broad scale of change at individual level, organizational level, and societal level. In this change process in higher education, staff development remains one of the key elements for university innovation and at the same time demands a systematic and holistic approach.......This paper starts with a critical approach to reflect on the current practice of quality assessment and assurance in higher education. This is followed by a proposal that in response to the global challenges for improving the quality of higher education, universities should take active actions...... of change by improving the quality of teaching and learning. From a constructivist perspective of understanding education and learning, this paper also discusses why and how universities should give more weight to learning and change the traditional role of teaching to an innovative approach of facilitation...

  1. INTERNATIONALIZATION IN HIGHER EDUCATION

    Directory of Open Access Journals (Sweden)

    Catalina Crisan-Mitra

    2016-03-01

    Full Text Available Internationalization of higher education is one of the key trends of development. There are several approaches on how to achieve competitiveness and performance in higher education and international academic mobility; students’ exchange programs, partnerships are some of the aspects that can play a significant role in this process. This paper wants to point out the student’s perception regarding two main directions: one about the master students’ expectation regarding how an internationalized master should be organized and should function, and second the degree of satisfaction of the beneficiaries of internationalized master programs from Babe-Bolyai University. This article is based on an empirical qualitative research that was implemented to students of an internationalized master from the Faculty of Economics and Business Administration. This research can be considered a useful example for those preoccupied to increase the quality of higher education and conclusions drawn have relevance both theoretically and especially practically.

  2. Higher spin gauge theories

    CERN Document Server

    Henneaux, Marc; Vasiliev, Mikhail A

    2017-01-01

    Symmetries play a fundamental role in physics. Non-Abelian gauge symmetries are the symmetries behind theories for massless spin-1 particles, while the reparametrization symmetry is behind Einstein's gravity theory for massless spin-2 particles. In supersymmetric theories these particles can be connected also to massless fermionic particles. Does Nature stop at spin-2 or can there also be massless higher spin theories. In the past strong indications have been given that such theories do not exist. However, in recent times ways to evade those constraints have been found and higher spin gauge theories have been constructed. With the advent of the AdS/CFT duality correspondence even stronger indications have been given that higher spin gauge theories play an important role in fundamental physics. All these issues were discussed at an international workshop in Singapore in November 2015 where the leading scientists in the field participated. This volume presents an up-to-date, detailed overview of the theories i...

  3. Efficacy of leaf extracts from some higher plants against sclerotium ...

    African Journals Online (AJOL)

    Au cours de la présente étude l'efficacité des extraits aqueux de 7 espèces végétales, Azadirachta indica, Carica papaya, Clausena anisata, Cymbopogon citratus, ... Les concentrations de 5 %,10 %, 15 % des extraits aqueux des feuilles des espèces botaniques et d'un fongicide de synthèse, le thiophanate-méthyl thiram ...

  4. Evidence That Putrescine Modulates the Higher Plant Photosynthetic Proton Circuit

    Science.gov (United States)

    Kotzabasis, Kiriakos; Kramer, David M.

    2012-01-01

    The light reactions of photosynthesis store energy in the form of an electrochemical gradient of protons, or proton motive force (pmf), comprised of electrical (Δψ) and osmotic (ΔpH) components. Both components can drive the synthesis of ATP at the chloroplast ATP synthase, but the ΔpH component also plays a key role in regulating photosynthesis, down-regulating the efficiency of light capture by photosynthetic antennae via the qE mechanism, and governing electron transfer at the cytochrome b6f complex. Differential partitioning of pmf into ΔpH and Δψ has been observed under environmental stresses and proposed as a mechanism for fine-tuning photosynthetic regulation, but the mechanism of this tuning is unknown. We show here that putrescine can alter the partitioning of pmf both in vivo (in Arabidopsis mutant lines and in Nicotiana wild type) and in vitro, suggesting that the endogenous titer of weak bases such as putrescine represents an unrecognized mechanism for regulating photosynthetic responses to the environment. PMID:22253808

  5. Evidence that putrescine modulates the higher plant photosynthetic proton circuit.

    Directory of Open Access Journals (Sweden)

    Nikolaos E Ioannidis

    Full Text Available The light reactions of photosynthesis store energy in the form of an electrochemical gradient of protons, or proton motive force (pmf, comprised of electrical (Δψ and osmotic (ΔpH components. Both components can drive the synthesis of ATP at the chloroplast ATP synthase, but the ΔpH component also plays a key role in regulating photosynthesis, down-regulating the efficiency of light capture by photosynthetic antennae via the q(E mechanism, and governing electron transfer at the cytochrome b(6f complex. Differential partitioning of pmf into ΔpH and Δψ has been observed under environmental stresses and proposed as a mechanism for fine-tuning photosynthetic regulation, but the mechanism of this tuning is unknown. We show here that putrescine can alter the partitioning of pmf both in vivo (in Arabidopsis mutant lines and in Nicotiana wild type and in vitro, suggesting that the endogenous titer of weak bases such as putrescine represents an unrecognized mechanism for regulating photosynthetic responses to the environment.

  6. Efficacy of leaf extracts from some higher plants against sclerotium ...

    African Journals Online (AJOL)

    thiram diazinon were used during the experimentation. Results show that at the concentration of 5 %, extracts of C. citratus were the most efficient for the control of S. rolfsii colonies. It was also observed that H. suaveolens, C. papaya, A. indica exhibited control of the pathogen at the 15 % concentration. La fonte de semis du ...

  7. Regulation of cell division in higher plants. Progress report, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, T.

    1993-09-01

    Recent work on the project has been focused almost exclusively on obtaining and characterizing CDNA clones encoding cylcin-dependent kinases (CDK), and cycling from pea. All of our work up to this time has relied on small PCR-generated CDNA clones of 2 putative pea CDKs and a putative pea mitotic cyclin, as well as anti-CDK antibodies of poor affinity and questionable specificity. Therefore, it has become a high priority for us to generate clones, probes and immunological tools in our own system. As of this writing, we have four putative CDKs (CdkPsl,2,3,& 4) and five putative cyclins (Cyc-Ps1,2,3,4,& 5), the DNA sequences of which have been determined to varying degrees of completeness.

  8. Evidence that putrescine modulates the higher plant photosynthetic proton circuit.

    Science.gov (United States)

    Ioannidis, Nikolaos E; Cruz, Jeffrey A; Kotzabasis, Kiriakos; Kramer, David M

    2012-01-01

    The light reactions of photosynthesis store energy in the form of an electrochemical gradient of protons, or proton motive force (pmf), comprised of electrical (Δψ) and osmotic (ΔpH) components. Both components can drive the synthesis of ATP at the chloroplast ATP synthase, but the ΔpH component also plays a key role in regulating photosynthesis, down-regulating the efficiency of light capture by photosynthetic antennae via the q(E) mechanism, and governing electron transfer at the cytochrome b(6)f complex. Differential partitioning of pmf into ΔpH and Δψ has been observed under environmental stresses and proposed as a mechanism for fine-tuning photosynthetic regulation, but the mechanism of this tuning is unknown. We show here that putrescine can alter the partitioning of pmf both in vivo (in Arabidopsis mutant lines and in Nicotiana wild type) and in vitro, suggesting that the endogenous titer of weak bases such as putrescine represents an unrecognized mechanism for regulating photosynthetic responses to the environment.

  9. Entrepreneurship and Higher Education

    Science.gov (United States)

    Potter, Jonathan, Ed.

    2008-01-01

    Stimulating innovative and growth-oriented entrepreneurship is a key economic and societal challenge to which universities and colleges have much to contribute. This book examines the role that higher education institutions are currently playing through teaching entrepreneurship and transferring knowledge and innovation to enterprises and…

  10. Liberty and Higher Education.

    Science.gov (United States)

    Thompson, Dennis F.

    1989-01-01

    John Stuart Mill's principle of liberty is discussed with the view that it needs to be revised to guide moral judgments in higher education. Three key elements need to be modified: the action that is constrained; the constraint on the action; and the agent whose action is constrained. (MLW)

  11. Navigating in higher education

    DEFF Research Database (Denmark)

    Thingholm, Hanne Balsby; Reimer, David; Keiding, Tina Bering

    Denne rapport er skrevet på baggrund af spørgeskemaundersøgelsen – Navigating in Higher Education (NiHE) – der rummer besvarelser fra 1410 bachelorstuderende og 283 undervisere fordelt på ni uddannelser fra Aarhus Universitet: Uddannelsesvidenskab, Historie, Nordisk sprog og litteratur...

  12. California's Future: Higher Education

    Science.gov (United States)

    Johnson, Hans

    2015-01-01

    California's higher education system is not keeping up with the changing economy. Projections suggest that the state's economy will continue to need more highly educated workers. In 2025, if current trends persist, 41 percent of jobs will require at least a bachelor's degree and 36 percent will require some college education short of a bachelor's…

  13. Higher-level Innovization

    DEFF Research Database (Denmark)

    Bandaru, Sunith; Tutum, Cem Celal; Deb, Kalyanmoy

    2011-01-01

    we introduce the higher-level innovization task through an application of a manufacturing process simulation for the Friction Stir Welding (FSW) process where commonalities among two different Pareto-optimal fronts are analyzed. Multiple design rules are simultaneously deciphered from each front...

  14. Cyberbullying in Higher Education

    Science.gov (United States)

    Minor, Maria A.; Smith, Gina S.; Brashen, Henry

    2013-01-01

    Bullying has extended beyond the schoolyard into online forums in the form of cyberbullying. Cyberbullying is a growing concern due to the effect on its victims. Current studies focus on grades K-12; however, cyberbullying has entered the world of higher education. The focus of this study was to identify the existence of cyberbullying in higher…

  15. Creativity in Higher Education

    Science.gov (United States)

    Gaspar, Drazena; Mabic, Mirela

    2015-01-01

    The paper presents results of research related to perception of creativity in higher education made by the authors at the University of Mostar from Bosnia and Herzegovina. This research was based on a survey conducted among teachers and students at the University. The authors developed two types of questionnaires, one for teachers and the other…

  16. Evaluation in Higher Education

    Science.gov (United States)

    Bognar, Branko; Bungic, Maja

    2014-01-01

    One of the means of transforming classroom experience is by conducting action research with students. This paper reports about the action research with university students. It has been carried out within a semester of the course "Methods of Upbringing". Its goal has been to improve evaluation of higher education teaching. Different forms…

  17. Pedagogy in Higher Education

    Directory of Open Access Journals (Sweden)

    Jorge Luis Dahik Cabrera

    2016-06-01

    Full Text Available This review determines the factors that should involve the current education from a university pedagogy that addresses sociological, psychological, axiological, cultural and economic conditions; also highlighting the skills to be addressed by the teacher in the knowledge society and the relevant number of functions that higher education institutions should be attributed it.

  18. Pedagogy in Higher Education

    OpenAIRE

    Jorge Luis Dahik Cabrera

    2016-01-01

    This review determines the factors that should involve the current education from a university pedagogy that addresses sociological, psychological, axiological, cultural and economic conditions; also highlighting the skills to be addressed by the teacher in the knowledge society and the relevant number of functions that higher education institutions should be attributed it.

  19. Leadership in Higher Education.

    Science.gov (United States)

    Robles, Harriett J.

    This paper examines leadership in higher education, specifically in community colleges. The first section reviews current definitions and theories of education, including transactional leadership (where there is an exchange between the leader and the follower) and transformational leadership (where the leader tries to change the framework itself…

  20. Competitiveness - Higher Education

    National Research Council Canada - National Science Library

    Labas, Istvan; Darabos, Eva; Nagy, Tunde Orsolya

    2016-01-01

    ... economy. In recent years, the frameworks of operation of higher education systems have gone through a total transformation. The number of applying students is continuously decreasing in some European countries therefore only those institutions can "survive" this shortfall, which are able to minimize the loss of the number of students. In...

  1. Futurism in Higher Education.

    Science.gov (United States)

    Fazio, Linda S.

    1988-01-01

    The concept of "futurism" in higher education program planning, self-study and goal setting is taking on increasing significance. Two research techniques for "futures forecasting" are discussed: the Delphi and the Scenario. These techniques have been used successfully in institutional self-study and program evaluation.…

  2. Higher-Order Hierarchies

    DEFF Research Database (Denmark)

    Ernst, Erik

    2003-01-01

    This paper introduces the notion of higher-order inheritance hierarchies. They are useful because they provide well-known benefits of object-orientation at the level of entire hierarchies-benefits which are not available with current approaches. Three facets must be adressed: First, it must...

  3. Higher spins and holography

    Science.gov (United States)

    Kraus, Per; Ross, Simon F.

    2013-05-01

    The principles of quantum mechanics and relativity impose rigid constraints on theories of massless particles with nonzero spin. Indeed, Yang-Mills theory and General Relativity are the unique solution in the case of spin-1 and spin-2. In asymptotically flat spacetime, there are fundamental obstacles to formulating fully consistent interacting theories of particles of spin greater than 2. However, indications are that such theories are just barely possible in asymptotically anti-de Sitter or de Sitter spacetimes, where the non-existence of an S-matrix provides an escape from the theorems restricting theories in Minkowski spacetime. These higher spin gravity theories are therefore of great intrinsic interest, since they, along with supergravity, provide the only known field theories generalizing the local invariance principles of Yang-Mills theory and General Relativity. While work on higher spin gravity goes back several decades, the subject has gained broader appeal in recent years due to its appearance in the AdS/CFT correspondence. In three and four spacetime dimensions, there exist duality proposals linking higher spin gravity theories to specific conformal field theories living in two and three dimensions respectively. The enlarged symmetry algebra of the conformal field theories renders them exactly soluble, which makes them excellent laboratories for understanding in detail the holographic mechanism behind AdS/CFT duality. Steady progress is also being made on better understanding the space of possible higher spin gravity theories and their physical content. This work includes classifying the possible field multiplets and their interactions, constructing exact solutions of the nonlinear field equations, and relating higher spin theories to string theory. A full understanding of these theories will involve coming to grips with the novel symmetry principles that enlarge those of General Relativity and Yang-Mills theory, and one can hope that this will provide

  4. Competitiveness - higher education

    Directory of Open Access Journals (Sweden)

    Labas Istvan

    2016-03-01

    Full Text Available Involvement of European Union plays an important role in the areas of education and training equally. The member states are responsible for organizing and operating their education and training systems themselves. And, EU policy is aimed at supporting the efforts of member states and trying to find solutions for the common challenges which appear. In order to make our future sustainable maximally; the key to it lies in education. The highly qualified workforce is the key to development, advancement and innovation of the world. Nowadays, the competitiveness of higher education institutions has become more and more appreciated in the national economy. In recent years, the frameworks of operation of higher education systems have gone through a total transformation. The number of applying students is continuously decreasing in some European countries therefore only those institutions can “survive” this shortfall, which are able to minimize the loss of the number of students. In this process, the factors forming the competitiveness of these budgetary institutions play an important role from the point of view of survival. The more competitive a higher education institution is, the greater the chance is that the students would like to continue their studies there and thus this institution will have a greater chance for the survival in the future, compared to ones lagging behind in the competition. Aim of our treatise prepared is to present the current situation and main data of the EU higher education and we examine the performance of higher education: to what extent it fulfils the strategy for smart, sustainable and inclusive growth which is worded in the framework of Europe 2020 programme. The treatise is based on analysis of statistical data.

  5. Plant Cytokinesis

    NARCIS (Netherlands)

    Smertenko, Andrei; Assaad, Farhah; Baluška, František; Bezanilla, Magdalena; Buschmann, Henrik; Drakakaki, Georgia; Hauser, Marie Theres; Janson, Marcel; Mineyuki, Yoshinobu; Moore, Ian; Müller, Sabine; Murata, Takashi; Otegui, Marisa S.; Panteris, Emmanuel; Rasmussen, Carolyn; Schmit, Anne Catherine; Šamaj, Jozef; Samuels, Lacey; Staehelin, L.A.; Damme, Van Daniel; Wasteneys, Geoffrey; Žárský, Viktor

    2017-01-01

    Plant cytokinesis is orchestrated by a specialized structure, the phragmoplast. The phragmoplast first occurred in representatives of Charophyte algae and then became the main division apparatus in land plants. Major cellular activities, including cytoskeletal dynamics, vesicle trafficking,

  6. Poisonous Plants

    Science.gov (United States)

    ... Publications and Products Programs Contact NIOSH NIOSH POISONOUS PLANTS Recommend on Facebook Tweet Share Compartir Photo courtesy ... U.S. Department of Agriculture Many native and exotic plants are poisonous to humans when ingested or if ...

  7. Chiral higher spin gravity

    Science.gov (United States)

    Krishnan, Chethan; Raju, Avinash

    2017-06-01

    We construct a candidate for the most general chiral higher spin theory with AdS3 boundary conditions. In the Chern-Simons language, on the left it has the Drinfeld-Sokolov reduced form, but on the right all charges and chemical potentials are turned on. Altogether (for the spin-3 case) these are 19 functions. Despite this, we show that the resulting metric has the form of the "most general" AdS3 boundary conditions discussed by Grumiller and Riegler. The asymptotic symmetry algebra is a product of a W3 algebra on the left and an affine s l (3 )k current algebra on the right, as desired. The metric and higher spin fields depend on all the 19 functions. We compare our work with previous results in the literature.

  8. Gamification in higher education

    OpenAIRE

    Langendahl, Per-Anders; Cook, Matthew; Mark-Herbert, Cecilia

    2016-01-01

    This report explores gamification as a pedagogic approach to engage and motivate students in higher education. Gamification is understood here to be the use of game elements in non-game contexts. Here game elements correspond to the characteristics of games, and context is defined as the activity and setting gamified. Gamification is deployed in various contexts such as running, shopping and learning and is therefore an open and multifaceted concept with multiple applications. The report deve...

  9. Aquatic plants

    DEFF Research Database (Denmark)

    Madsen, T. V.; Sand-Jensen, K.

    2006-01-01

    Aquatic fl owering plants form a relatively young plant group on an evolutionary timescale. The group has developed over the past 80 million years from terrestrial fl owering plants that re-colonised the aquatic environment after 60-100 million years on land. The exchange of species between...... terrestrial and aquatic environments continues today and is very intensive along stream banks. In this chapter we describe the physical and chemical barriers to the exchange of plants between land and water....

  10. The TriForC database: a comprehensive up-to-date resource of plant triterpene biosynthesis.

    Science.gov (United States)

    Miettinen, Karel; Iñigo, Sabrina; Kreft, Lukasz; Pollier, Jacob; De Bo, Christof; Botzki, Alexander; Coppens, Frederik; Bak, Søren; Goossens, Alain

    2018-01-04

    Triterpenes constitute a large and important class of plant natural products with diverse structures and functions. Their biological roles range from membrane structural components over plant hormones to specialized plant defence compounds. Furthermore, triterpenes have great potential for a variety of commercial applications such as vaccine adjuvants, anti-cancer drugs, food supplements and agronomic agents. Their biosynthesis is carried out through complicated, branched pathways by multiple enzyme types that include oxidosqualene cyclases, cytochrome P450s, and UDP-glycosyltransferases. Given that the number of characterized triterpene biosynthesis enzymes has been growing fast recently, the need for a database specifically focusing on triterpene enzymology became eminent. Here, we present the TriForC database (http://bioinformatics.psb.ugent.be/triforc/), encompassing a comprehensive catalogue of triterpene biosynthesis enzymes. This highly interlinked database serves as a user-friendly access point to versatile data sets of enzyme and compound features, enabling the scanning of a complete catalogue of experimentally validated triterpene enzymes, their substrates and products, as well as the pathways they constitute in various plant species. The database can be accessed by direct browsing or through convenient search tools including keyword, BLAST, plant species and substructure options. This database will facilitate gene mining and creating genetic toolboxes for triterpene synthetic biology. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  11. Medicinal Plants.

    Science.gov (United States)

    Phillipson, J. David

    1997-01-01

    Highlights the demand for medicinal plants as pharmaceuticals and the demand for health care treatments worldwide and the issues that arise from this. Discusses new drugs from plants, anticancer drugs, antiviral drugs, antimalarial drugs, herbal remedies, quality, safety, efficacy, and conservation of plants. Contains 30 references. (JRH)

  12. Poisonous plants.

    Science.gov (United States)

    Poppenga, Robert H

    2010-01-01

    A large number of plants can cause adverse effects when ingested by animals or people. Plant toxicity is due to a wide diversity of chemical toxins that include alkaloids, glycosides, proteins and amino acids. There are several notable toxic plants for which a specific chemical responsible for toxicity has not been determined. There are many examples of species differences in terms of their sensitivity to intoxication from plants. Pets, such as dogs and cats, and people, especially children, are frequently exposed to the same toxic plants due to their shared environments. On the other hand, livestock are exposed to toxic plants that are rarely involved in human intoxications due to the unique environments in which they are kept. Fortunately, adverse effects often do not occur or are generally mild following most toxic plant ingestions and no therapeutic intervention is necessary. However, some plants are extremely toxic and ingestion of small amounts can cause rapid death. The diagnosis of plant intoxication can be challenging, especially in veterinary medicine where a history of exposure to a toxic plant is often lacking. Analytical tests are available to detect some plant toxins, although their diagnostic utility is often limited by test availability and timeliness of results. With a few notable exceptions, antidotes for plant toxins are not available. However, general supportive and symptomatic care often is sufficient to successfully treat a symptomatic patient.

  13. Expression of MicroRNA-15b and the Glycosyltransferase GCNT3 Correlates with Antitumor Efficacy of Rosemary Diterpenes in Colon and Pancreatic Cancer

    Science.gov (United States)

    González-Vallinas, Margarita; Molina, Susana; Vicente, Gonzalo; Zarza, Virginia; Martín-Hernández, Roberto; García-Risco, Mónica R.; Fornari, Tiziana; Reglero, Guillermo; de Molina, Ana Ramírez

    2014-01-01

    Colorectal and pancreatic cancers remain important contributors to cancer mortality burden and, therefore, new therapeutic approaches are urgently needed. Rosemary (Rosmarinus officinalis L.) extracts and its components have been reported as natural potent antiproliferative agents against cancer cells. However, to potentially apply rosemary as a complementary approach for cancer therapy, additional information regarding the most effective composition, its antitumor effect in vivo and its main molecular mediators is still needed. In this work, five carnosic acid-rich supercritical rosemary extracts with different chemical compositions have been assayed for their antitumor activity both in vivo (in nude mice) and in vitro against colon and pancreatic cancer cells. We found that the antitumor effect of carnosic acid together with carnosol was higher than the sum of their effects separately, which supports the use of the rosemary extract as a whole. In addition, gene and microRNA expression analyses have been performed to ascertain its antitumor mechanism, revealing that up-regulation of the metabolic-related gene GCNT3 and down-regulation of its potential epigenetic modulator miR-15b correlate with the antitumor effect of rosemary. Moreover, plasmatic miR-15b down-regulation was detected after in vivo treatment with rosemary. Our results support the use of carnosic acid-rich rosemary extract as a complementary approach in colon and pancreatic cancer and indicate that GCNT3 expression may be involved in its antitumor mechanism and that miR-15b might be used as a non-invasive biomarker to monitor rosemary anticancer effect. PMID:24892299

  14. Higher Education in Scandinavia

    DEFF Research Database (Denmark)

    Nielsen, Jørgen Lerche; Andreasen, Lars Birch

    2015-01-01

    Higher education systems around the world have been undergoing fundamental changes through the last 50 years from more narrow self-sustaining universities for the elite and into mass universities, where new groups of students have been recruited and the number of students enrolled has increased...... dramatically. In adjusting to the role of being a mass educational institution, universities have been challenged on how to cope with external pressures, such as forces of globalization and international markets, increased national and international competition for students and research grants, increased...... an impact on the educational systems in Scandinavia, and what possible futures can be envisioned?...

  15. Higher engineering mathematics

    CERN Document Server

    John Bird

    2014-01-01

    A practical introduction to the core mathematics principles required at higher engineering levelJohn Bird's approach to mathematics, based on numerous worked examples and interactive problems, is ideal for vocational students that require an advanced textbook.Theory is kept to a minimum, with the emphasis firmly placed on problem-solving skills, making this a thoroughly practical introduction to the advanced mathematics engineering that students need to master. The extensive and thorough topic coverage makes this an ideal text for upper level vocational courses. Now in

  16. Autoluminescent plants.

    Directory of Open Access Journals (Sweden)

    Alexander Krichevsky

    Full Text Available Prospects of obtaining plants glowing in the dark have captivated the imagination of scientists and layman alike. While light emission has been developed into a useful marker of gene expression, bioluminescence in plants remained dependent on externally supplied substrate. Evolutionary conservation of the prokaryotic gene expression machinery enabled expression of the six genes of the lux operon in chloroplasts yielding plants that are capable of autonomous light emission. This work demonstrates that complex metabolic pathways of prokaryotes can be reconstructed and function in plant chloroplasts and that transplastomic plants can emit light that is visible by naked eye.

  17. Autoluminescent plants.

    Science.gov (United States)

    Krichevsky, Alexander; Meyers, Benjamin; Vainstein, Alexander; Maliga, Pal; Citovsky, Vitaly

    2010-11-12

    Prospects of obtaining plants glowing in the dark have captivated the imagination of scientists and layman alike. While light emission has been developed into a useful marker of gene expression, bioluminescence in plants remained dependent on externally supplied substrate. Evolutionary conservation of the prokaryotic gene expression machinery enabled expression of the six genes of the lux operon in chloroplasts yielding plants that are capable of autonomous light emission. This work demonstrates that complex metabolic pathways of prokaryotes can be reconstructed and function in plant chloroplasts and that transplastomic plants can emit light that is visible by naked eye.

  18. Production and glyco-engineering of immunomodulatory helminth glycoproteins in plants

    Science.gov (United States)

    Wilbers, Ruud H. P.; Westerhof, Lotte B.; van Noort, Kim; Obieglo, Katja; Driessen, Nicole N.; Everts, Bart; Gringhuis, Sonja I.; Schramm, Gabriele; Goverse, Aska; Smant, Geert; Bakker, Jaap; Smits, Hermelijn H.; Yazdanbakhsh, Maria; Schots, Arjen; Hokke, Cornelis H.

    2017-01-01

    Helminth parasites control host-immune responses by secreting immunomodulatory glycoproteins. Clinical trials and mouse model studies have demonstrated the potential of helminth-derived glycoproteins for the treatment of immune-related diseases, like allergies and autoimmune diseases. Studies are however hampered by the limited availability of native parasite-derived proteins. Moreover, recombinant protein production systems have thus far been unable to reconstitute helminth-like glycosylation essential for the functionality of some helminth glycoproteins. Here we exploited the flexibility of the N-glycosylation machinery of plants to reconstruct the helminth glycoproteins omega-1 and kappa-5, two major constituents of immunomodulatory Schistosoma mansoni soluble egg antigens. Fine-tuning transient co-expression of specific glycosyltransferases in Nicotiana benthamiana enabled the synthesis of Lewis X (LeX) and LDN/LDN-F glycan motifs as found on natural omega-1 and kappa-5, respectively. In vitro and in vivo evaluation of the introduction of native LeX motifs on plant-produced omega-1 confirmed that LeX on omega-1 contributes to the glycoprotein’s Th2-inducing properties. These data indicate that mimicking the complex carbohydrate structures of helminths in plants is a promising strategy to allow targeted evaluation of therapeutic glycoproteins for the treatment of inflammatory disorders. In addition, our results offer perspectives for the development of effective anti-helminthic vaccines by reconstructing native parasite glycoprotein antigens. PMID:28393916

  19. Synthesis of Rhizobial Exopolysaccharides and Their Importance for Symbiosis with Legume Plants

    Directory of Open Access Journals (Sweden)

    Małgorzata Marczak

    2017-12-01

    Full Text Available Rhizobia dwell and multiply in the soil and represent a unique group of bacteria able to enter into a symbiotic interaction with plants from the Fabaceae family and fix atmospheric nitrogen inside de novo created plant organs, called nodules. One of the key determinants of the successful interaction between these bacteria and plants are exopolysaccharides, which represent species-specific homo- and heteropolymers of different carbohydrate units frequently decorated by non-carbohydrate substituents. Exopolysaccharides are typically built from repeat units assembled by the Wzx/Wzy-dependent pathway, where individual subunits are synthesized in conjunction with the lipid anchor undecaprenylphosphate (und-PP, due to the activity of glycosyltransferases. Complete oligosaccharide repeat units are transferred to the periplasmic space by the activity of the Wzx flippase, and, while still being anchored in the membrane, they are joined by the polymerase Wzy. Here we have focused on the genetic control over the process of exopolysaccharides (EPS biosynthesis in rhizobia, with emphasis put on the recent advancements in understanding the mode of action of the key proteins operating in the pathway. A role played by exopolysaccharide in Rhizobium–legume symbiosis, including recent data confirming the signaling function of EPS, is also discussed.

  20. Towards higher intensities

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Over the past 2 weeks, commissioning of the machine protection system has advanced significantly, opening up the possibility of higher intensity collisions at 3.5 TeV. The intensity has been increased from 2 bunches of 1010 protons to 6 bunches of 2x1010 protons. Luminosities of 6x1028 cm-2s-1 have been achieved at the start of fills, a factor of 60 higher than those provided for the first collisions on 30 March.   The recent increase in LHC luminosity as recorded by the experiments. (Graph courtesy of the experiments and M. Ferro-Luzzi) To increase the luminosity further, the commissioning crews are now trying to push up the intensity of the individual proton bunches. After the successful injection of nominal intensity bunches containing 1.1x1011 protons, collisions were subsequently achieved at 450 GeV with these intensities. However, half-way through the first ramping of these nominal intensity bunches to 3.5 TeV on 15 May, a beam instability was observed, leading to partial beam loss...

  1. Teaching at higher levels

    Science.gov (United States)

    1998-11-01

    Undergraduate physics programmes for the 21st century were under discussion at a recent event held in Arlington, USA, open to two or three members of the physics faculties of universities from across the whole country. The conference was organized by the American Association of Physics Teachers with co-sponsorship from the American Institute of Physics, the American Physical Society and Project Kaleidoscope. Among the various aims were to learn about physics departments that have successfully revitalized their undergraduate physics programmes with innovative introductory physics courses and multi-track majors programmes. Engineers and life scientists were to be asked directly how physics programmes can better serve their students, and business leaders would be speaking on how physics departments can help to prepare their students for the diverse careers that they will eventually follow. It was planned to highlight ways that departments could fulfil their responsibilities towards trainee teachers, to identify the resources needed for revitalizing a department's programme, and to develop guidelines and recommendations for a funding programme to support collaborative efforts among physics departments for carrying out the enhancements required. More details about the conference can be found on the AAPT website (see http://www.aapt.org/programs/rupc.html). Meanwhile the UK's Higher Education Funding Council has proposed a two-pronged approach to the promotion of high quality teaching and learning, as well as widening participation in higher education from 1999-2000. A total of £60m should be available to support these initiatives by the year 2001-2002. As part of this scheme the Council will invite bids from institutions to support individual academics in enhancing learning and teaching, as well as in recognition of individual excellence. As with research grants, such awards would enable staff to pursue activities such as the development of teaching materials

  2. Plant cell wall biosynthesis: genetic, biochemical and functional genomics approaches to the identification of key genes.

    Science.gov (United States)

    Farrokhi, Naser; Burton, Rachel A; Brownfield, Lynette; Hrmova, Maria; Wilson, Sarah M; Bacic, Antony; Fincher, Geoffrey B

    2006-03-01

    Cell walls are dynamic structures that represent key determinants of overall plant form, plant growth and development, and the responses of plants to environmental and pathogen-induced stresses. Walls play centrally important roles in the quality and processing of plant-based foods for both human and animal consumption, and in the production of fibres during pulp and paper manufacture. In the future, wall material that constitutes the major proportion of cereal straws and other crop residues will find increasing application as a source of renewable fuel and composite manufacture. Although the chemical structures of most wall constituents have been defined in detail, the enzymes involved in their synthesis and remodelling remain largely undefined, particularly those involved in polysaccharide biosynthesis. There have been real recent advances in our understanding of cellulose biosynthesis in plants, but, with few exceptions, the identities and modes of action of polysaccharide synthases and other glycosyltransferases that mediate the biosynthesis of the major non-cellulosic wall polysaccharides are not known. Nevertheless, emerging functional genomics and molecular genetics technologies are now allowing us to re-examine the central questions related to wall biosynthesis. The availability of the rice, Populus trichocarpa and Arabidopsis genome sequences, a variety of mutant populations, high-density genetic maps for cereals and other industrially important plants, high-throughput genome and transcript analysis systems, extensive publicly available genomics resources and an increasing armoury of analysis systems for the definition of candidate gene function will together allow us to take a systems approach to the description of wall biosynthesis in plants.

  3. Higher Order Mode Fibers

    DEFF Research Database (Denmark)

    Israelsen, Stine Møller

    This PhD thesis considers higher order modes (HOMs) in optical fibers. That includes their excitation and characteristics. Within the last decades, HOMs have been applied both for space multiplexing in optical communications, group velocity dispersion management and sensing among others....... The research presented in this thesis falls in three parts. In the first part, a first time demonstration of the break of the azimuthal symmetry of the Bessel-like LP0X modes is presented. This effect, known as the bowtie effect, causes the mode to have an azimuthal dependence as well as a quasi......-radial polarization as opposed to the linear polarization of the LP0X modes. The effect is investigated numerically in a double cladding fiber with an outer aircladding using a full vectorial modesolver. Experimentally, the bowtie modes are excited using a long period grating and their free space characteristics...

  4. Plant blindness and the implications for plant conservation.

    Science.gov (United States)

    Balding, Mung; Williams, Kathryn J H

    2016-12-01

    Plant conservation initiatives lag behind and receive considerably less funding than animal conservation projects. We explored a potential reason for this bias: a tendency among humans to neither notice nor value plants in the environment. Experimental research and surveys have demonstrated higher preference for, superior recall of, and better visual detection of animals compared with plants. This bias has been attributed to perceptual factors such as lack of motion by plants and the tendency of plants to visually blend together but also to cultural factors such as a greater focus on animals in formal biological education. In contrast, ethnographic research reveals that many social groups have strong bonds with plants, including nonhierarchical kinship relationships. We argue that plant blindness is common, but not inevitable. If immersed in a plant-affiliated culture, the individual will experience language and practices that enhance capacity to detect, recall, and value plants, something less likely to occur in zoocentric societies. Therefore, conservation programs can contribute to reducing this bias. We considered strategies that might reduce this bias and encourage plant conservation behavior. Psychological research demonstrates that people are more likely to support conservation of species that have human-like characteristics and that support for conservation can be increased by encouraging people to practice empathy and anthropomorphism of nonhuman species. We argue that support for plant conservation may be garnered through strategies that promote identification and empathy with plants. © 2016 Society for Conservation Biology.

  5. Learning higher mathematics

    CERN Document Server

    Pontrjagin, Lev Semenovič

    1984-01-01

    Lev Semenovic Pontrjagin (1908) is one of the outstanding figures in 20th century mathematics. In a long career he has made fundamental con­ tributions to many branches of mathematics, both pure and applied. He has received every honor that a grateful government can bestow. Though in no way constrained to do so, he has through the years taught mathematics courses at Moscow State University. In the year 1975 he set himself the task of writing a series of books on secondary school and beginning university mathematics. In his own words, "I wished to set forth the foundations of higher mathematics in a form that would have been accessible to myself as a lad, but making use of all my experience as a scientist and a teacher, ac­ cumulated over many years. " The present volume is a translation of the first two out of four moderately sized volumes on this theme planned by Pro­ fessor Pontrjagin. The book begins at the beginning of modern mathematics, analytic ge­ ometry in the plane and 3-dimensional space. Refin...

  6. Autoluminescent Plants

    OpenAIRE

    Krichevsky, Alexander; Meyers, Benjamin; Vainstein, Alexander; Maliga, Pal; Citovsky, Vitaly

    2010-01-01

    Prospects of obtaining plants glowing in the dark have captivated the imagination of scientists and layman alike. While light emission has been developed into a useful marker of gene expression, bioluminescence in plants remained dependent on externally supplied substrate. Evolutionary conservation of the prokaryotic gene expression machinery enabled expression of the six genes of the lux operon in chloroplasts yielding plants that are capable of autonomous light emission. This work demonstra...

  7. Chromatin dynamics in plants

    NARCIS (Netherlands)

    Fransz, P.F.; Jong, de J.H.

    2002-01-01

    Recent studies in yeast, animals and plants have provided major breakthroughs in unraveling the molecular mechanism of higher-order gene regulation. In conjunction with the DNA code, proteins that are involved in chromatin remodeling, histone modification and epigenetic imprinting form a large

  8. Towards Multi Fuel SOFC Plant

    DEFF Research Database (Denmark)

    Rokni, Masoud; Clausen, Lasse Røngaard; Bang-Møller, Christian

    2011-01-01

    Complete Solid Oxide Fuel Cell (SOFC) plants fed by several different fuels are suggested and analyzed. The plants sizes are about 10 kW which is suitable for single family house with needs for both electricity and heat. Alternative fuels such as, methanol, DME (Di-Methyl Ether) and ethanol...... are also considered and the results will be compared with the base plant fed by Natural Gas (NG). A single plant design will be suggested that can be fed with methanol, DME and ethanol whenever these fuels are available. It will be shown that the plant fed by ethanol will have slightly higher electrical...... efficiency compared with other fuels. A methanator will be suggested to be included into the plants design in order to produce methane from the fuel before entering the anode side of the SOFC stacks. Increasing methane content will decrease the needed compressor effect and thereby increase the plant power....

  9. What makes cyclodextrin glycosyltransferase a transglycosylase

    NARCIS (Netherlands)

    Leemhuis, Reinder Johannes

    2003-01-01

    All living organisms need energy from their environment for maintenance and growth. The carbohydrate starch is such an energy source. It is an abundant carbohydrate composed of amylose and amylopectin polymers. Before organisms can utilize the starch, it has to be degraded to smaller sugars suitable

  10. Higher Efficiency HVAC Motors

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, Charles Joseph

    2018-02-13

    failure prone capacitors from the power stage. Q-Sync’s simpler electronics also result in higher efficiency because it eliminates the power required by the PCB to perform the obviated power conversions and PWM processes after line synchronous operating speed is reached in the first 5 seconds of operation, after which the PWM circuits drop out and a much less energy intensive “pass through” circuit takes over, allowing the grid-supplied AC power to sustain the motor’s ongoing operation.

  11. Comparative analysis of fungal genomes reveals different plant cell wall degrading capacity in fungi

    Science.gov (United States)

    2013-01-01

    Background Fungi produce a variety of carbohydrate activity enzymes (CAZymes) for the degradation of plant polysaccharide materials to facilitate infection and/or gain nutrition. Identifying and comparing CAZymes from fungi with different nutritional modes or infection mechanisms may provide information for better understanding of their life styles and infection models. To date, over hundreds of fungal genomes are publicly available. However, a systematic comparative analysis of fungal CAZymes across the entire fungal kingdom has not been reported. Results In this study, we systemically identified glycoside hydrolases (GHs), polysaccharide lyases (PLs), carbohydrate esterases (CEs), and glycosyltransferases (GTs) as well as carbohydrate-binding modules (CBMs) in the predicted proteomes of 103 representative fungi from Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota. Comparative analysis of these CAZymes that play major roles in plant polysaccharide degradation revealed that fungi exhibit tremendous diversity in the number and variety of CAZymes. Among them, some families of GHs and CEs are the most prevalent CAZymes that are distributed in all of the fungi analyzed. Importantly, cellulases of some GH families are present in fungi that are not known to have cellulose-degrading ability. In addition, our results also showed that in general, plant pathogenic fungi have the highest number of CAZymes. Biotrophic fungi tend to have fewer CAZymes than necrotrophic and hemibiotrophic fungi. Pathogens of dicots often contain more pectinases than fungi infecting monocots. Interestingly, besides yeasts, many saprophytic fungi that are highly active in degrading plant biomass contain fewer CAZymes than plant pathogenic fungi. Furthermore, analysis of the gene expression profile of the wheat scab fungus Fusarium graminearum revealed that most of the CAZyme genes related to cell wall degradation were up-regulated during plant infection. Phylogenetic analysis also

  12. Comparative analysis of fungal genomes reveals different plant cell wall degrading capacity in fungi.

    Science.gov (United States)

    Zhao, Zhongtao; Liu, Huiquan; Wang, Chenfang; Xu, Jin-Rong

    2013-04-23

    Fungi produce a variety of carbohydrate activity enzymes (CAZymes) for the degradation of plant polysaccharide materials to facilitate infection and/or gain nutrition. Identifying and comparing CAZymes from fungi with different nutritional modes or infection mechanisms may provide information for better understanding of their life styles and infection models. To date, over hundreds of fungal genomes are publicly available. However, a systematic comparative analysis of fungal CAZymes across the entire fungal kingdom has not been reported. In this study, we systemically identified glycoside hydrolases (GHs), polysaccharide lyases (PLs), carbohydrate esterases (CEs), and glycosyltransferases (GTs) as well as carbohydrate-binding modules (CBMs) in the predicted proteomes of 103 representative fungi from Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota. Comparative analysis of these CAZymes that play major roles in plant polysaccharide degradation revealed that fungi exhibit tremendous diversity in the number and variety of CAZymes. Among them, some families of GHs and CEs are the most prevalent CAZymes that are distributed in all of the fungi analyzed. Importantly, cellulases of some GH families are present in fungi that are not known to have cellulose-degrading ability. In addition, our results also showed that in general, plant pathogenic fungi have the highest number of CAZymes. Biotrophic fungi tend to have fewer CAZymes than necrotrophic and hemibiotrophic fungi. Pathogens of dicots often contain more pectinases than fungi infecting monocots. Interestingly, besides yeasts, many saprophytic fungi that are highly active in degrading plant biomass contain fewer CAZymes than plant pathogenic fungi. Furthermore, analysis of the gene expression profile of the wheat scab fungus Fusarium graminearum revealed that most of the CAZyme genes related to cell wall degradation were up-regulated during plant infection. Phylogenetic analysis also revealed a complex

  13. Plant Behavior

    Science.gov (United States)

    Liu, Dennis W. C.

    2014-01-01

    Plants are a huge and diverse group of organisms, ranging from microscopic marine phytoplankton to enormous terrestrial trees epitomized by the giant sequoia: 300 feet tall, living 3000 years, and weighing as much as 3000 tons. For this plant issue of "CBE-Life Sciences Education," the author focuses on a botanical topic that most…

  14. Metabolic engineering of dhurrin in transgenic Arabidopsis plants with marginal inadvertent effects on the metabolome and transcriptome.

    Science.gov (United States)

    Kristensen, Charlotte; Morant, Marc; Olsen, Carl Erik; Ekstrøm, Claus T; Galbraith, David W; Møller, Birger Lindberg; Bak, Søren

    2005-02-01

    Focused and nontargeted approaches were used to assess the impact associated with introduction of new high-flux pathways in Arabidopsis thaliana by genetic engineering. Transgenic A. thaliana plants expressing the entire biosynthetic pathway for the tyrosine-derived cyanogenic glucoside dhurrin as accomplished by insertion of CYP79A1, CYP71E1, and UGT85B1 from Sorghum bicolor were shown to accumulate 4% dry-weight dhurrin with marginal inadvertent effects on plant morphology, free amino acid pools, transcriptome, and metabolome. In a similar manner, plants expressing only CYP79A1 accumulated 3% dry weight of the tyrosine-derived glucosinolate, p-hydroxybenzylglucosinolate with no morphological pleitropic effects. In contrast, insertion of CYP79A1 plus CYP71E1 resulted in stunted plants, transcriptome alterations, accumulation of numerous glucosides derived from detoxification of intermediates in the dhurrin pathway, and in loss of the brassicaceae-specific UV protectants sinapoyl glucose and sinapoyl malate and kaempferol glucosides. The accumulation of glucosides in the plants expressing CYP79A1 and CYP71E1 was not accompanied by induction of glycosyltransferases, demonstrating that plants are constantly prepared to detoxify xenobiotics. The pleiotrophic effects observed in plants expressing sorghum CYP79A1 and CYP71E1 were complemented by retransformation with S. bicolor UGT85B. These results demonstrate that insertion of high-flux pathways directing synthesis and intracellular storage of high amounts of a cyanogenic glucoside or a glucosinolate is achievable in transgenic A. thaliana plants with marginal inadvertent effects on the transcriptome and metabolome.

  15. plantsUPS: a database of plants' Ubiquitin Proteasome System

    Directory of Open Access Journals (Sweden)

    Su Zhen

    2009-05-01

    Full Text Available Abstract Background The ubiquitin 26S/proteasome system (UPS, a serial cascade process of protein ubiquitination and degradation, is the last step for most cellular proteins. There are many genes involved in this system, but are not identified in many species. The accumulating availability of genomic sequence data is generating more demands in data management and analysis. Genomics data of plants such as Populus trichocarpa, Medicago truncatula, Glycine max and others are now publicly accessible. It is time to integrate information on classes of genes for complex protein systems such as UPS. Results We developed a database of higher plants' UPS, named 'plantsUPS'. Both automated search and manual curation were performed in identifying candidate genes. Extensive annotations referring to each gene were generated, including basic gene characterization, protein features, GO (gene ontology assignment, microarray probe set annotation and expression data, as well as cross-links among different organisms. A chromosome distribution map, multi-sequence alignment, and phylogenetic trees for each species or gene family were also created. A user-friendly web interface and regular updates make plantsUPS valuable to researchers in related fields. Conclusion The plantsUPS enables the exploration and comparative analysis of UPS in higher plants. It now archives > 8000 genes from seven plant species distributed in 11 UPS-involved gene families. The plantsUPS is freely available now to all users at http://bioinformatics.cau.edu.cn/plantsUPS.

  16. Plant Macrofossils

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past vegetation and environmental change derived from plant remains large enough to be seen without a microscope (macrofossils), such as leaves, needles,...

  17. T Plant

    Data.gov (United States)

    Federal Laboratory Consortium — Arguably the second most historic building at Hanford is the T Plant.This facility is historic in that it's the oldest remaining nuclear facility in the country that...

  18. Plant Allergies

    OpenAIRE

    Predny, Mary Lorraine

    2009-01-01

    Allergic reactions are caused by an overactive immune system response to a foreign substance such as pollen, dust, or molds. This publication goes over the common plants that cause allergies and ways to prevent allergies while gardening.

  19. Plants. Ag Ed Environmental Education Series.

    Science.gov (United States)

    Tulloch, Rodney W.

    Designed to serve as a resource tool in a high school vocational agriculture curriculum dealing with the environment as it relates to agriculture, this unit is concerned with plants. Plants are defined and their characteristics described. A section on the effects of environment on higher plants covers temperature, light, water, nutrients, air,…

  20. The endocytic network in plants.

    Science.gov (United States)

    Samaj, Jozef; Read, Nick D; Volkmann, Dieter; Menzel, Diedrik; Baluska, Frantisek

    2005-08-01

    Endocytosis and vesicle recycling via secretory endosomes are essential for many processes in multicellular organisms. Recently, higher plants have provided useful experimental model systems to study these processes. Endocytosis and secretory endosomes in plants play crucial roles in polar tip growth, a process in which secretory and endocytic pathways are integrated closely. Plant endocytosis and endosomes are important for auxin-mediated cell-cell communication, gravitropic responses, stomatal movements, cytokinesis and cell wall morphogenesis. There is also evidence that F-actin is essential for endocytosis and that plant-specific myosin VIII is an endocytic motor in plants. Last, recent results indicate that the trans Golgi network in plants should be considered an integral part of the endocytic network.

  1. Plant Physiological Aspects of Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, E.; Fan, T.W-M.; Higashi, R.M.; Silk, W.K.

    2002-07-10

    The element silicon, Si, represents an anomaly in plant physiology (Epstein, 1994, 1999b). Plants contain the element in amounts comparable to those of such macronutrient elements as phosphorus, calcium, magnesium, viz. at tissue concentrations (dry weight basis) of about 0.1-10%, although both lower and higher values may be encountered. In some plants, such as rice and sugarcane, Si may be the mineral element present in largest amount. In much of plant physiological research, however, Si is considered a nonentity. Thus, not a single formulation of the widely used nutrient solutions includes Si. Experimental plants grown in these solutions are therefore abnormally low in their content of the element, being able to obtain only what Si is present as an unavoidable contaminant of the nutrient salts used, and from the experimental environment and their own seeds. The reason for the astonishing discrepancy between the prominence of Si in plants and its neglect in much of the enterprise of plant physiological research is that Si does not qualify as an ''essential'' element. Ever since the introduction of the solution culture method in the middle of the last century (Epstein, 1999a, b) it has been found that higher plants can grow in nutrient solutions in the formulation of which Si is not included. The only exceptions are the Equisitaceae (horsetails or scouring rushes), for which Si is a quantitatively major essential element.

  2. Sex and parasites: genomic and transcriptomic analysis of Microbotryum lychnidis-dioicae, the biotrophic and plant-castrating anther smut fungus.

    Science.gov (United States)

    Perlin, Michael H; Amselem, Joelle; Fontanillas, Eric; Toh, Su San; Chen, Zehua; Goldberg, Jonathan; Duplessis, Sebastien; Henrissat, Bernard; Young, Sarah; Zeng, Qiandong; Aguileta, Gabriela; Petit, Elsa; Badouin, Helene; Andrews, Jared; Razeeq, Dominique; Gabaldón, Toni; Quesneville, Hadi; Giraud, Tatiana; Hood, Michael E; Schultz, David J; Cuomo, Christina A

    2015-06-16

    The genus Microbotryum includes plant pathogenic fungi afflicting a wide variety of hosts with anther smut disease. Microbotryum lychnidis-dioicae infects Silene latifolia and replaces host pollen with fungal spores, exhibiting biotrophy and necrosis associated with altering plant development. We determined the haploid genome sequence for M. lychnidis-dioicae and analyzed whole transcriptome data from plant infections and other stages of the fungal lifecycle, revealing the inventory and expression level of genes that facilitate pathogenic growth. Compared to related fungi, an expanded number of major facilitator superfamily transporters and secretory lipases were detected; lipase gene expression was found to be altered by exposure to lipid compounds, which signaled a switch to dikaryotic, pathogenic growth. In addition, while enzymes to digest cellulose, xylan, xyloglucan, and highly substituted forms of pectin were absent, along with depletion of peroxidases and superoxide dismutases that protect the fungus from oxidative stress, the repertoire of glycosyltransferases and of enzymes that could manipulate host development has expanded. A total of 14% of the genome was categorized as repetitive sequences. Transposable elements have accumulated in mating-type chromosomal regions and were also associated across the genome with gene clusters of small secreted proteins, which may mediate host interactions. The unique absence of enzyme classes for plant cell wall degradation and maintenance of enzymes that break down components of pollen tubes and flowers provides a striking example of biotrophic host adaptation.

  3. Microorganism and Fungi Drive Evolution of Plant Synapses

    Directory of Open Access Journals (Sweden)

    Frantisek eBaluska

    2013-08-01

    Full Text Available In the course of plant evolution, there is an obvious trend toward an increased complexity of plant bodies, as well as an increased sophistication of plant behavior and communication. Phenotypic plasticity of plants is based on the polar auxin transport machinery that is directly linked with plant sensory systems impinging on plant behavior and adaptive responses. Similar to the emergence and evolution of eukaryotic cells, evolution of land plants was also shaped and driven by infective and symbiotic microorganisms. These microorganisms are the driving force behind the evolution of plant synapses and other neuronal aspects of higher plants; this is especially pronounced in the root apices. Plant synapses allow synaptic cell-cell communication and coordination in plants, as well as sensory-motor integration in root apices searching for water and mineral nutrition. These neuronal aspects of higher plants are closely linked with their unique ability to adapt to environmental changes.

  4. Microorganism and filamentous fungi drive evolution of plant synapses.

    Science.gov (United States)

    Baluška, František; Mancuso, Stefano

    2013-01-01

    In the course of plant evolution, there is an obvious trend toward an increased complexity of plant bodies, as well as an increased sophistication of plant behavior and communication. Phenotypic plasticity of plants is based on the polar auxin transport machinery that is directly linked with plant sensory systems impinging on plant behavior and adaptive responses. Similar to the emergence and evolution of eukaryotic cells, evolution of land plants was also shaped and driven by infective and symbiotic microorganisms. These microorganisms are the driving force behind the evolution of plant synapses and other neuronal aspects of higher plants; this is especially pronounced in the root apices. Plant synapses allow synaptic cell-cell communication and coordination in plants, as well as sensory-motor integration in root apices searching for water and mineral nutrition. These neuronal aspects of higher plants are closely linked with their unique ability to adapt to environmental changes.

  5. Internationalization of Chinese Higher Education

    Science.gov (United States)

    Chen, Linhan; Huang, Danyan

    2013-01-01

    This paper probes into the development of internationalization of higher education in China from ancient times to modern times, including the emergence of international connections in Chinese higher education and the subsequent development of such connections, the further development of internationalization of Chinese higher education, and the…

  6. Higher Education Studies in Japan

    Science.gov (United States)

    Kaneko, Motohisa

    2010-01-01

    The rapid development of higher education in the postwar period has given rise to various problems, and higher education studies in Japan have developed in response to them. What have been the major issues, and how did academic research respond to them, in postwar Japan? This article delineates an outline of higher education studies in general,…

  7. Functional Characterization of UDP-apiose Synthases from Bryophytes and Green Algae Provides Insight into the Appearance of Apiose-containing Glycans during Plant Evolution.

    Science.gov (United States)

    Smith, James; Yang, Yiwen; Levy, Shahar; Adelusi, Oluwatoyin Oluwayemi; Hahn, Michael G; O'Neill, Malcolm A; Bar-Peled, Maor

    2016-10-07

    Apiose is a branched monosaccharide that is present in the cell wall pectic polysaccharides rhamnogalacturonan II and apiogalacturonan and in numerous plant secondary metabolites. These apiose-containing glycans are synthesized using UDP-apiose as the donor. UDP-apiose (UDP-Api) together with UDP-xylose is formed from UDP-glucuronic acid (UDP-GlcA) by UDP-Api synthase (UAS). It was hypothesized that the ability to form Api distinguishes vascular plants from the avascular plants and green algae. UAS from several dicotyledonous plants has been characterized; however, it is not known if avascular plants or green algae produce this enzyme. Here we report the identification and functional characterization of UAS homologs from avascular plants (mosses, liverwort, and hornwort), from streptophyte green algae, and from a monocot (duckweed). The recombinant UAS homologs all form UDP-Api from UDP-glucuronic acid albeit in different amounts. Apiose was detected in aqueous methanolic extracts of these plants. Apiose was detected in duckweed cell walls but not in the walls of the avascular plants and algae. Overexpressing duckweed UAS in the moss Physcomitrella patens led to an increase in the amounts of aqueous methanol-acetonitrile-soluble apiose but did not result in discernible amounts of cell wall-associated apiose. Thus, bryophytes and algae likely lack the glycosyltransferase machinery required to synthesize apiose-containing cell wall glycans. Nevertheless, these plants may have the ability to form apiosylated secondary metabolites. Our data are the first to provide evidence that the ability to form apiose existed prior to the appearance of rhamnogalacturonan II and apiogalacturonan and provide new insights into the evolution of apiose-containing glycans. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Enzymes from Higher Eukaryotes for Industrial Biocatalysis

    Directory of Open Access Journals (Sweden)

    Zhibin Liu

    2004-01-01

    Full Text Available The industrial production of fine chemicals, feed and food ingredients, pharmaceuticals, agrochemicals and their respective intermediates relies on an increasing application of biocatalysis, i.e. on enzyme or whole-cell catalyzed conversions of molecules. Simple procedures for discovery, cloning and over-expression as well as fast growth favour fungi, yeasts and especially bacteria as sources of biocatalysts. Higher eukaryotes also harbour an almost unlimited number of potential biocatalysts, although to date the limited supply of enzymes, the high heterogeneity of enzyme preparations and the hazard of infectious contaminants keep some interesting candidates out of reach for industrial bioprocesses. In the past only a few animal and plant enzymes from agricultural waste materials were employed in food processing. The use of bacterial expression strains or non-conventional yeasts for the heterologous production of efficient eukaryotic enzymes can overcome the bottleneck in enzyme supply and provide sufficient amounts of homogenous enzyme preparations for reliable and economically feasible applications at large scale. Ideal enzymatic processes represent an environmentally friendly, »near-to-completion« conversion of (mostly non-natural substrates to pure products. Recent developments demonstrate the commercial feasibility of large-scale biocatalytic processes employing enzymes from higher eukaryotes (e.g. plants, animals and also their usefulness in some small-scale industrial applications.

  9. transgenic plants

    African Journals Online (AJOL)

    been initiated in this area by the Global Pest. Resistance Management Programme located at. MSU. Through effective resistance management training, pesticide use patterns change, and the effective lift: span of pesticides and host plant resistance technology increases. Effective resistance management can mean reduced.

  10. Poisonous plants

    African Journals Online (AJOL)

    decontamination using activated charcoal within the first 2 hours of ingestion and with supportive measures (see Table 1). Antidotes are only of potential value in the treatment of plants containing cardiac glycosides and those that present with cholinergic and anticholinergic toxidromes. The authors of this article identified ...

  11. Plant-based remediation processes

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Dharmendra Kumar (ed.) [Belgian Nuclear Research Centre (SCK.CEN), Mol (Belgium). Radiological Impact and Performance Assessment Division

    2013-11-01

    A valuable source of information for scientists in the field of environmental pollution and remediation. Describes the latest biotechnological methods for the treatment of contaminated soils. Includes case studies and protocols. Phytoremediation is an emerging technology that employs higher plants for the clean-up of contaminated environments. Basic and applied research have unequivocally demonstrated that selected plant species possess the genetic potential to accumulate, degrade, metabolize and immobilize a wide range of contaminants. The main focus of this volume is on the recent advances of technologies using green plants for remediation of various metals and metalloids. Topics include biomonitoring of heavy metal pollution, amendments of higher uptake of toxic metals, transport of heavy metals in plants, and toxicity mechanisms. Further chapters discuss agro-technological methods for minimizing pollution while improving soil quality, transgenic approaches to heavy metal remediation and present protocols for metal remediation via in vitro root cultures.

  12. Approaches to translational plant science

    DEFF Research Database (Denmark)

    Dresbøll, Dorte Bodin; Christensen, Brian; Thorup-Kristensen, Kristian

    2015-01-01

    Translational science deals with the dilemma between basic research and the practical application of scientific results. In translational plant science, focus is on the relationship between agricultural crop production and basic science in various research fields, but primarily in the basic plant...... science. Scientific and technological developments have allowed great progress in our understanding of plant genetics and molecular physiology, with potentials for improving agricultural production. However, this development has led to a separation of the laboratory-based research from the crop production...... is lessened. In our opinion, implementation of translational plant science is a necessity in order to solve the agricultural challenges of producing food and materials in the future. We suggest an approach to translational plant science forcing scientists to think beyond their own area and to consider higher...

  13. Comparative transcriptome analysis of different chemotypes elucidates withanolide biosynthesis pathway from medicinal plant Withania somnifera.

    Science.gov (United States)

    Gupta, Parul; Goel, Ridhi; Agarwal, Aditya Vikram; Asif, Mehar Hasan; Sangwan, Neelam Singh; Sangwan, Rajender Singh; Trivedi, Prabodh Kumar

    2015-12-21

    Withania somnifera is one of the most valuable medicinal plants synthesizing secondary metabolites known as withanolides. Despite pharmaceutical importance, limited information is available about the biosynthesis of withanolides. Chemo-profiling of leaf and root tissues of Withania suggest differences in the content and/or nature of withanolides in different chemotypes. To identify genes involved in chemotype and/or tissue-specific withanolide biosynthesis, we established transcriptomes of leaf and root tissues of distinct chemotypes. Genes encoding enzymes for intermediate steps of terpenoid backbone biosynthesis with their alternatively spliced forms and paralogous have been identified. Analysis suggests differential expression of large number genes among leaf and root tissues of different chemotypes. Study also identified differentially expressing transcripts encoding cytochrome P450s, glycosyltransferases, methyltransferases and transcription factors which might be involved in chemodiversity in Withania. Virus induced gene silencing of the sterol ∆7-reductase (WsDWF5) involved in the synthesis of 24-methylene cholesterol, withanolide backbone, suggests role of this enzyme in biosynthesis of withanolides. Information generated, in this study, provides a rich resource for functional analysis of withanolide-specific genes to elucidate chemotype- as well as tissue-specific withanolide biosynthesis. This genomic resource will also help in development of new tools for functional genomics and breeding in Withania.

  14. Wages and Higher Education Participation

    OpenAIRE

    Eleftheriou, Konstantinos; Athanasiou, George; Petrakis, Panagiotis

    2009-01-01

    The paper develops a model for the screening mechanism for higher education, within an adverse selection framework. Specifically it examines the effect of wage earned by high school graduates on higher education participation. The model pinpoints a positive relation between the “high school” wage and the number of candidates entered in higher education with positive influences on the quality of selection mechanism. An empirical examination is conducted, using U.S. data, in order to investigat...

  15. PV integration into a CSP plant

    Science.gov (United States)

    Carvajal, Javier López; Barea, Jose M.; Barragan, Jose; Ortega, Carlos

    2017-06-01

    This paper describes a preliminary techno-economic analysis of the integration of a PV plant into an optimized Parabolic Trough Plant in order to reduce the online consumptions and thus, increase the net electricity injected into the grid. The idea is to assess the feasibility of such project and see what configuration would be the optimal. An extra effort has been made in terms of modelling as the analysis has to be done to the integrated CSP + PV plant instead of analyzing them independently. Two different technologies have been considered for the PV plant, fix and one-axis tracking. Additionally three different scenarios have been considered for the CSP plant auxiliary consumptions as they are essential for determining the optimal PV plant (the higher the auxiliary consumption the higher the optimal PV plant). As could be expected, the results for all cases with PV show an improvement in terms of electricity generation and also in terms of LCOE with respect to the CSP plant. Such improvement is slightly higher with tracking technology for this specific study. Although this exercise has been done to an already designed CSP plant (so only the PV plant had to be optimized), the methodology could be applied for the optimization of an integrated CSP + PV plant during the design phase.

  16. A widespread plant-fungal-bacterial symbiosis promotes plant biodiversity, plant nutrition and seedling recruitment.

    Science.gov (United States)

    van der Heijden, Marcel G A; de Bruin, Susanne; Luckerhoff, Ludo; van Logtestijn, Richard S P; Schlaeppi, Klaus

    2016-02-01

    Highly diverse microbial assemblages colonize plant roots. It is still poorly understood whether different members of this root microbiome act synergistically by supplying different services (for example, different limiting nutrients) to plants and plant communities. In order to test this, we manipulated the presence of two widespread plant root symbionts, arbuscular mycorrhizal fungi and nitrogen-fixing rhizobia bacteria in model grassland communities established in axenic microcosms. Here, we demonstrate that both symbionts complement each other resulting in increased plant diversity, enhanced seedling recruitment and improved nutrient acquisition compared with a single symbiont situation. Legume seedlings obtained up to 15-fold higher productivity if they formed an association with both symbionts, opposed to productivity they reached with only one symbiont. Our results reveal the importance of functional diversity of symbionts and demonstrate that different members of the root microbiome can complement each other in acquiring different limiting nutrients and in driving important ecosystem functions.

  17. Plants as sources of antiviral agents | Abonyi | African Journal of ...

    African Journals Online (AJOL)

    A lot of success has been achieved in the screening of plants for antibacterial, antifungal and antiviral actions. The use of plants or plant products, traditionally, as antiviral agents is relatively wider than their use in modern medicine. Some antiviral substances have so far been isolated from higher plants, algae and lichens.

  18. Root exudate cocktails: the link between plant diversity and soil microorganisms?

    National Research Council Canada - National Science Library

    Steinauer, Katja; Chatzinotas, Antonis; Eisenhauer, Nico

    2016-01-01

    .... We tested whether higher root exudate diversity enhances soil microbial biomass and diversity in a plant diversity gradient, thereby negating significant plant diversity effects on soil microbial properties...

  19. Radiosensitivity in plants

    Energy Technology Data Exchange (ETDEWEB)

    Nauman, A F

    1979-01-01

    The report presents a compilation of available data on the sensitivity of plants to ionizing radiation, and provides basic information on methods of determining such sensitivities, or of estimating radiosensitivities by calcuation of the nuclear factors upon which they depend. The scope of the data presented here is necessarily limited to the most generally useful radiobiological end points and to the most commonly-used types of radiation. Many of the factors which influence radiosensitivity, particularly nuclear factors, will be discussed. Emphasis will be upon whole-plant studies done at Brookhaven National Laboratory by A.H. Sparrow and his associates, since these studies are the source of most of the available radiosensitivity data and of all the sensitivity predictions listed here. Data presented here include summaries of experimentally-determined radiosensitivities at various end points for both herbaceous and woody higher plants, and for a few species of ferns and lower plants. The algae and fungi have not been considered here due to space limitations.

  20. Effective Communication in Higher Education

    Science.gov (United States)

    Howard, Melissa

    2014-01-01

    The intent for this paper is to show that communication within the higher education field is a current problem. By looking first at the different styles, forms, and audiences for communication, the reader will hopefully gain perspective as to why this is such a problem in higher education today. Since the Millennial generation is the newest set of…

  1. Disruptive Technologies in Higher Education

    Science.gov (United States)

    Flavin, Michael

    2012-01-01

    This paper analyses the role of "disruptive" innovative technologies in higher education. In this country and elsewhere, Higher Education Institutions (HEIs) have invested significant sums in learning technologies, with Virtual Learning Environments (VLEs) being more or less universal, but these technologies have not been universally…

  2. Makerere Journal of Higher Education

    African Journals Online (AJOL)

    Makerere Journal of Higher Education (MAJOHE) is the official publication of the East African School of Higher Education Studies and Development (Makerere University). The goal of the Journal is to provide a visible outlet for definitive articles that discuss the theory, practice and policies relating to the role, development, ...

  3. Extremal Higher Spin Black Holes

    NARCIS (Netherlands)

    Bañados, M.; Castro, A.; Faraggi, A.; Jottar, J.I.

    The gauge sector of three-dimensional higher spin gravities can be formulated as a Chern-Simons theory. In this context, a higher spin black hole corresponds to a flat connection with suitable holonomy (smoothness) conditions which are consistent with the properties of a generalized thermal

  4. Queering Transformation in Higher Education

    Science.gov (United States)

    Msibi, Thabo

    2013-01-01

    Transformation in higher education has tended to focus on race and sex, at the expense of other forms of discrimination. This article addresses the silencing of "queer" issues in higher education. Using queer theory as a framework, and drawing on current literature, popular media reports, two personal critical incidents and a project…

  5. Higher Education and Ethical Value

    Science.gov (United States)

    Lee, Jeong-Kyu

    2017-01-01

    The purpose of this study is to explore the importance of ethical value in higher education as well as the relevance between ethical value and higher education. In order to examine the study logically, three research questions are addressed: First, what is value, ethical value, and Asiatic ethical value? Second, for whom and what is higher…

  6. The Higher Education Research Archipelago

    Science.gov (United States)

    Macfarlane, Bruce

    2012-01-01

    Ever since he stumbled into doing higher education research as a young academic in the 1980s, the author has been trying to understand it as a "field" of study. His career, as a former business lecturer, then an academic developer and now an associate professor for higher education working in an Education Faculty has given him opportunities to see…

  7. The Overselling of Higher Education

    Science.gov (United States)

    Leef, George C.

    2006-01-01

    There is not enough substance behind a degree to warrant the ubiquitous belief that a stint in higher education is a "sine qua non" for success in America. While college diplomas may translate into higher-paying jobs for some, high school signifies little in the way of education these days, so jaded employers' estimates of the real value of…

  8. Innovation Processes in Higher Education.

    Science.gov (United States)

    Berg, Barbro; Ostergren, Bertil

    1979-01-01

    Innovation processes in the Swedish Higher Education System are described and related to a general theory of innovation. Using the theories of Kurt Lewin, characteristics of higher education as a social system and factors which determine the nature of the forces towards a certain type of change are defined. (JMF)

  9. Latino Males in Higher Education

    Science.gov (United States)

    Excelencia in Education, 2016

    2016-01-01

    This 2016 fact sheet profiles the status of Latino males in higher education, providing information on population, college enrollment, and educational attainment. While college enrollment among Latino males continues to increase, they still lag behind Latino females in college enrollment--a disparity that increases as the level of higher education…

  10. Polish Higher Education: Intersectoral Distinctiveness

    Science.gov (United States)

    Musial, Joanna

    2014-01-01

    This study analyzes degrees of differences between the private and public sectors of Polish higher education. It finds them to be strong: Polish private institutions function very differently from Polish public institutions and these differences correspond with those found in the literature on higher education elsewhere in the world. Polish…

  11. Higher education and economic growth

    OpenAIRE

    Richard H. Mattoon

    2006-01-01

    The future of higher education and its relationship to economic growth were the focus of a one-day conference at the Chicago Fed on November 2, 2005. Cosponsored by the bank, the Committee on Institutional Cooperation, and the Midwestern Higher Education Compact, the event brought together over 100 academic, business, and government leaders.

  12. Innovations in Higher Education? Hah!

    Science.gov (United States)

    Kirschner, Ann

    2012-01-01

    One can hardly mention higher education today without hearing the word "innovation," or its understudies "change," "reinvention," "transformation." Last summer the National Governors Association opened its meeting with a plenary session on higher education, innovation, and economic growth. But there is nothing funny about the need for innovation…

  13. Higher Education, Poverty and Development

    Science.gov (United States)

    Tilak, Jandhyala B. G.

    2010-01-01

    There is a presumption among many policy makers that higher education is not necessary for economic growth and development; it is literacy and basic education and at best secondary education that are argued to be important. Estimates of internal rate of return contributed to strengthening of such a presumption. Accordingly, higher education has…

  14. Higher Education: Open for Business

    Science.gov (United States)

    Gilde, Christian, Ed.

    2007-01-01

    This book addresses a problem in higher learning, which is newly recognized in the academic spotlight: the overcommercialization of higher education. The book asks that you, the reader, think about the following: Did you go to a Coke or Pepsi school? Do your children attend a Nike or Adidas school? Is the college in your town a Dell or Gateway…

  15. Strategic Planning for Higher Education.

    Science.gov (United States)

    Kotler, Philip; Murphy, Patrick E.

    1981-01-01

    The framework necessary for achieving a strategic planning posture in higher education is outlined. The most important benefit of strategic planning for higher education decision makers is that it forces them to undertake a more market-oriented and systematic approach to long- range planning. (Author/MLW)

  16. Higher Franz-Reidemeister torsion

    CERN Document Server

    Igusa, Kiyoshi

    2002-01-01

    The book is devoted to the theory of topological higher Franz-Reidemeister torsion in K-theory. The author defines the higher Franz-Reidemeister torsion based on Volodin's K-theory and Borel's regulator map. He describes its properties and generalizations and studies the relation between the higher Franz-Reidemeister torsion and other torsions used in K-theory: Whitehead torsion and Ray-Singer torsion. He also presents methods of computing higher Franz-Reidemeister torsion, illustrates them with numerous examples, and describes various applications of higher Franz-Reidemeister torsion, particularly for the study of homology of mapping class groups. Packed with up-to-date information, the book provides a unique research and reference tool for specialists working in algebraic topology and K-theory.

  17. Maize yield and quality in response to plant density and application of a novel plant growth regulator

    NARCIS (Netherlands)

    Zhang, Q.; Zhang, L.; Evers, J.B.; Werf, van der W.; Zhang, W.; Duan, L.

    2014-01-01

    Farmers in China have gradually increased plant density in maize to achieve higher yields, but this has increased risk of lodging due to taller and weaker stems at higher plant densities. Plant growth regulators can be used to reduce lodging risk. In this study, for the first time, the performance

  18. Illuminating a plant's tissue-specific metabolic diversity using computational metabolomics and information theory.

    Science.gov (United States)

    Li, Dapeng; Heiling, Sven; Baldwin, Ian T; Gaquerel, Emmanuel

    2016-11-22

    Secondary metabolite diversity is considered an important fitness determinant for plants' biotic and abiotic interactions in nature. This diversity can be examined in two dimensions. The first one considers metabolite diversity across plant species. A second way of looking at this diversity is by considering the tissue-specific localization of pathways underlying secondary metabolism within a plant. Although these cross-tissue metabolite variations are increasingly regarded as important readouts of tissue-level gene function and regulatory processes, they have rarely been comprehensively explored by nontargeted metabolomics. As such, important questions have remained superficially addressed. For instance, which tissues exhibit prevalent signatures of metabolic specialization? Reciprocally, which metabolites contribute most to this tissue specialization in contrast to those metabolites exhibiting housekeeping characteristics? Here, we explore tissue-level metabolic specialization in Nicotiana attenuata, an ecological model with rich secondary metabolism, by combining tissue-wide nontargeted mass spectral data acquisition, information theory analysis, and tandem MS (MS/MS) molecular networks. This analysis was conducted for two different methanolic extracts of 14 tissues and deconvoluted 895 nonredundant MS/MS spectra. Using information theory analysis, anthers were found to harbor the most specialized metabolome, and most unique metabolites of anthers and other tissues were annotated through MS/MS molecular networks. Tissue-metabolite association maps were used to predict tissue-specific gene functions. Predictions for the function of two UDP-glycosyltransferases in flavonoid metabolism were confirmed by virus-induced gene silencing. The present workflow allows biologists to amortize the vast amount of data produced by modern MS instrumentation in their quest to understand gene function.

  19. Teaching Creatively in Higher Education

    DEFF Research Database (Denmark)

    Chemi, Tatiana; Zhou, Chunfang

    The topic of this booklet is a synthesis of relevant research in the field of creativity in higher education, with focus on creative teaching methods. By means of literature review and research findings this booklet describes a wide range of contexts and effects on student learning and develop......­ment, together with teacher motivation and overall satisfaction. This booklet meets the need for renewal and creation in higher education, in order to address the challenges of the future, focusing on the benefits of teaching crea­tively at higher education....

  20. Dispatchable Solar Power Plant Project

    Energy Technology Data Exchange (ETDEWEB)

    Price, Henry [Solar Dynamics LLC, Broomfield, CO (United States)

    2018-01-31

    to DSP plants. These results estimate that the cost of the DSP plant is about 10% higher than a similarly-sized and operated frame combustion turbine and slightly cheaper than an aero derivative combustion turbine when APS reference fuel and emissions costs are included. The DSP plant cost is based on a single, first-of-a-kind plant, and it is likely that subsequent plants would be less expensive.