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  • 301.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bergman, A
    Ericson, I
    Oxidation of Glycine via the Respiratory Chain in Mitochondria Prepared from Different Parts of Spinach.1980Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 65, nr 2, s. 389-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mitochondria were prepared from roots, stalks, leaves, and leaf veins of spinach. The mitochondrial preparations were examined for their ability to oxidize glycine via the respiratory chain. It is shown that the glycine-oxidizing capacity is restricted to photosynthetically active tissue. The activity is present in mitochondria from the green parts of the leaves, but not in mitochondria from roots, stalks, or leaf veins.

  • 302.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Edwards, G E
    Isolation of Mitochondria from Leaf Tissue of Panicum miliaceum, a NAD-Malic Enzyme Type C(4) Plant.1983Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 71, nr 1, s. 24-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mechanical isolation procedure was developed to study the respiratory properties of mitochondria from the mesophyll and bundle sheath tissue of Panicum miliaceum, a NAD-malic enzyme C(4) plant. A mesophyll fraction and a bundle sheath fraction were obtained from young leaves by differential mechanical treatment. The purity of both fractions was about 80%, based on analysis of the cross-contamination of ribulose bisphosphate carboxylase activity and phosphoenolpyruvate carboxylase activity.Mitochondria were isolated from the two fractions by differential centrifugation and Percoll density gradient centrifugation. The enrichment of mitochondria relative to chloroplast material was about 75-fold in both preparations.Both types of mitochondria oxidized NADH and succinate with respiratory control. Malate oxidation in mesophyll mitochondria was sensitive to KCN and showed good respiratory control. In bundle sheath mitochondria, malate oxidation was largely insensitive to KCN and showed no respiratory control. The oxidation was strongly inhibited by salicylhydroxamic acid, showing that the alternative oxidase was involved. The bundle sheath mitochondria of this type of C(4) species contribute to C(4) photosynthesis through decarboxylation of malate. Malate oxidation linked to an uncoupled, alternative pathway may allow decarboxylation to proceed without the restraints which might occur via coupled electron flow through the cytochrome chain.

  • 303.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    EDWARDS, GE
    HENRICSON, D
    ERICSON, I
    THE LOCALIZATION OF SERINE HYDROXYMETHYLTRANSFERASE IN LEAVES OF C-3 AND C-4 SPECIES1985Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 64, nr 1, s. 29-33Artikkel i tidsskrift (Fagfellevurdert)
  • 304.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ERICSON, I
    SEPARATION OF SPINACH LEAF MITOCHONDRIA ACCORDING TO SURFACE-PROPERTIES - PARTITION IN AQUEOUS POLYMER 2-PHASE SYSTEMS1987Inngår i: Methods in Enzymology, ISSN 0076-6879, E-ISSN 1557-7988, Vol. 148, s. 434-442Artikkel i tidsskrift (Fagfellevurdert)
  • 305.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Igamberdiev, Abir U.
    The origin of cytosolic ATP in photosynthetic cells2016Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 157, nr 3, s. 367-379Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    In photosynthetically active cells, both chloroplasts and mitochondria have the capacity to produce ATP via photophosphorylation and oxidative phosphorylation, respectively. Thus, theoretically, both organelles could provide ATP for the cytosol, but the extent, to which they actually do this, and how the process is regulated, both remain unclear. Most of the evidence discussed comes from experiments with rapid fractionation of isolated protoplasts subjected to different treatments in combination with application of specific inhibitors. The results obtained indicate that, under conditions where ATP demand for photosynthetic CO2 fixation is sufficiently high, the mitochondria supply the bulk of ATP for the cytosol. In contrast, under stress conditions where CO2 fixation is severely limited, ATP will build up in chloroplasts and it can then be exported to the cytosol, by metabolite shuttle mechanisms. Thus, depending on the conditions, either mitochondria or chloroplasts can supply the bulk of ATP for the cytosol. This supply of ATP is discussed in relation to the idea that mitochondrial functions may be tuned to provide an optimal environment for the chloroplast. By balancing cellular redox states, mitochondria can contribute to an optimal photosynthetic capacity.

  • 306.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Lernmark, U
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    The contribution of mitochondria to energetic metabolism in photosynthetic cells1995Inngår i: Journal of Bioenergetics and Biomembranes, ISSN 0145-479X, E-ISSN 1573-6881, Vol. 27, nr 4, s. 415-421Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mitochondria fulfill important functions in photosynthetic cells not only in darkness but also in light. Mitochondrial oxidative phosphorylation is probably the main mechanism to supply ATP for extrachloroplastic functions in both conditions. Furthermore, during photosynthesis mitochondrial electron transport is important for regulation of the redox balance in the cell. This makes mitochondrial function an integral part of a flexible metabolic system in the photosynthetic cell. This flexibility is probably very important in order to allow the metabolism to override disturbances caused by the changing environment which plants are adapted to.

  • 307.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Petit, Patrice X
    Møller, Ian M
    Purification and characterization of plant mitochondria and submitochondrial particles1994Inngår i: Methods in Enzymology, ISSN 0076-6879, E-ISSN 1557-7988, Vol. 228, s. 424-431Artikkel, forskningsoversikt (Fagfellevurdert)
  • 308.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    WIGGE, B
    INFLUENCE OF PHOTORESPIRATION ON ATP/ADP RATIOS IN THE CHLOROPLASTS, MITOCHONDRIA, AND CYTOSOL, STUDIES BY RAPID FRACTIONATION OF BARLEY (HORDEUM-VULGARE) PROTOPLASTS1988Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 88, nr 1, s. 69-76Artikkel i tidsskrift (Fagfellevurdert)
  • 309. Geisler, Matt
    et al.
    Kleczkowski, Leszek
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Karpinski, Stanislaw
    A universal algorithm for genome-wide in silicio identification of biologically significant gene promoter putative cis-regulatory-elements; identification of new elements for reactive oxygen species and sucrose signaling in Arabidopsis.2006Inngår i: Plant Journal, ISSN 0960-7412, Vol. 45, nr 3, s. 384-98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Short motifs of many cis-regulatory elements (CREs) can be found in the promoters of most Arabidopsis genes, and this raises the question of how their presence can confer specific regulation. We developed a universal algorithm to test the biological significance of CREs by first identifying every Arabidopsis gene with a CRE and then statistically correlating the presence or absence of the element with the gene expression profile on multiple DNA microarrays. This algorithm was successfully verified for previously characterized abscisic acid, ethylene, sucrose and drought responsive CREs in Arabidopsis, showing that the presence of these elements indeed correlates with treatment-specific gene induction. Later, we used standard motif sampling methods to identify 128 putative motifs induced by excess light, reactive oxygen species and sucrose. Our algorithm was able to filter 20 out of 128 novel CREs which significantly correlated with gene induction by either heat, reactive oxygen species and/or sucrose. The position, orientation and sequence specificity of CREs was tested in silicio by analyzing the expression of genes with naturally occurring sequence variations. In three novel CREs the forward orientation correlated with sucrose induction and the reverse orientation with sucrose suppression. The functionality of the predicted novel CREs was experimentally confirmed using Arabidopsis cell-suspension cultures transformed with short promoter fragments or artificial promoters fused with the GUS reporter gene. Our genome-wide analysis opens up new possibilities for in silicio verification of the biological significance of newly discovered CREs, and allows for subsequent selection of such CREs for experimental studies.

  • 310. Geisler, Matt
    et al.
    Wilczynska, Malgorzata
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Karpinski, Stanislaw
    Kleczkowski, Leszek
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Toward a blueprint for UDP-glucose pyrophosphorylase structure/function properties: homology-modeling analyses.2004Inngår i: Plant Molecular Biology, ISSN 0167-4412, Vol. 56, nr 5, s. 783-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    UDP-glucose pyrophosphorylase (UGPase) is an important enzyme of synthesis of sucrose, cellulose, and several other polysaccharides in all plants. The protein is evolutionarily conserved among eukaryotes, but has little relation, aside from its catalytic reaction, to UGPases of prokaryotic origin. Using protein homology modeling strategy, 3D structures for barley, poplar, and Arabidopsis UGPases have been derived, based on recently published crystal structure of human UDP-N-acetylglucosamine pyrophosphorylase. The derived 3D structures correspond to a bowl-shaped protein with the active site at a central groove, and a C-terminal domain that includes a loop (I-loop) possibly involved in dimerization. Data on a plethora of earlier described UGPase mutants from a variety of eukaryotic organisms have been revisited, and we have, in most cases, verified the role of each mutation in enzyme catalysis/regulation/structural integrity. We have also found that one of two alternatively spliced forms of poplar UGPase has a very short I-loop, suggesting differences in oligomerization ability of the two isozymes. The derivation of the structural model for plant UGPase should serve as a useful blueprint for further function/structure studies on this protein.

  • 311. Geisler-Lee, Jane
    et al.
    Geisler, Matt
    Coutinho, Pedro M
    Segerman, Bo
    Nishikubo, Nobuyuki
    Takahashi, Junko
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Aspeborg, Henrik
    Djerbi, Soraya
    Master, Emma
    Andersson-Gunnerås, Sara
    Sundberg, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Karpinski, Stanislaw
    Teeri, Tuula T
    Kleczkowski, Leszek
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Henrissat, Bernard
    Mellerowicz, Ewa J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Poplar carbohydrate-active enzymes. Gene identification and expression analyses.2006Inngår i: Plant Physiology, ISSN 0032-0889, Vol. 140, nr 3, s. 946-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Over 1,600 genes encoding carbohydrate-active enzymes (CAZymes) in the Populus trichocarpa (Torr. & Gray) genome were identified based on sequence homology, annotated, and grouped into families of glycosyltransferases, glycoside hydrolases, carbohydrate esterases, polysaccharide lyases, and expansins. Poplar (Populus spp.) had approximately 1.6 times more CAZyme genes than Arabidopsis (Arabidopsis thaliana). Whereas most families were proportionally increased, xylan and pectin-related families were underrepresented and the GT1 family of secondary metabolite-glycosylating enzymes was overrepresented in poplar. CAZyme gene expression in poplar was analyzed using a collection of 100,000 expressed sequence tags from 17 different tissues and compared to microarray data for poplar and Arabidopsis. Expression of genes involved in pectin and hemicellulose metabolism was detected in all tissues, indicating a constant maintenance of transcripts encoding enzymes remodeling the cell wall matrix. The most abundant transcripts encoded sucrose synthases that were specifically expressed in wood-forming tissues along with cellulose synthase and homologs of KORRIGAN and ELP1. Woody tissues were the richest source of various other CAZyme transcripts, demonstrating the importance of this group of enzymes for xylogenesis. In contrast, there was little expression of genes related to starch metabolism during wood formation, consistent with the preferential flux of carbon to cell wall biosynthesis. Seasonally dormant meristems of poplar showed a high prevalence of transcripts related to starch metabolism and surprisingly retained transcripts of some cell wall synthesis enzymes. The data showed profound changes in CAZyme transcriptomes in different poplar tissues and pointed to some key differences in CAZyme genes and their regulation between herbaceous and woody plants.

  • 312. Gendre, Delphine
    et al.
    Baral, Anirban
    Dang, Xie
    Esnay, Nicolas
    Boutté, Yohann
    Stanislas, Thomas
    Vain, Thomas
    Claverol, Stéphane
    Gustavsson, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Lin, Deshu
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Institute of Biochemistry and Biology, Plant Physiology, Universityof Potsdam, Germany.
    Bhalerao, Rishikesh P.
    Rho-of-plant activated root hair formation requires Arabidopsis YIP4a/b gene function2019Inngår i: Development, ISSN 0950-1991, E-ISSN 1477-9129, Vol. 146, nr 5, artikkel-id dev168559Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Root hairs are protrusions from root epidermal cells with crucial roles in plant soil interactions. Although much is known about patterning, polarity and tip growth of root hairs, contributions of membrane trafficking to hair initiation remain poorly understood. Here, we demonstrate that the trans-Golgi network-localized YPT-INTERACTING PROTEIN 4a and YPT-INTERACTING PROTEIN 4b (YIP4a/b) contribute to activation and plasma membrane accumulation of Rho-of-plant (ROP) small GTPases during hair initiation, identifying YIP4a/b as central trafficking components in ROP-dependent root hair formation.

  • 313.
    Gentili, Francesco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Phosphorus, nitrogen and their interactions affect N-2 fixation, N isotope fractionation and N partitioning in Hippophae rhamnoides2006Inngår i: Symbiosis, ISSN 0334-5114, E-ISSN 1878-7665, Vol. 41, nr 1, s. 39-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interactive effects of varying phosphorus and nitrogen supplies on N-2 fixation, N isotope fractionation during N uptake, and N partitioning among plant parts were studied in the actinorhizal plant Hippophae rhamnoides L. (sea buckthorn). Plants were grown for six weeks after inoculation with the N-2-fixing actinomycete Frankia and differences in N accumulation were used to quantify N-2 fixation. N-15 natural abundance was analysed to study N isotope fractionation in specific plant parts in plants receiving different levels of N and P. Furthermore, the root system was split to study N isotope fractionation in roots supplied with different levels of N and P. Phosphorus stimulated N-2 fixation by direct effects on nodule dry matter and nodule function, rather than indirectly via plant growth. Phosphorus also stimulated N uptake from solution and influenced N isotope fractionation during N uptake. The inclusion of N-15 natural abundance analyses made it possible to detect P effects on N uptake, fractionation and N-2 fixation even though the plants used both N-2 fixation and combined N as N sources.

  • 314.
    Gentili, Francesco
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Nilsson, Marie-Charlotte
    Zackrisson, Olle
    DeLuca, Thomas H
    Sellstedt, Anita
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Physiological and molecular diversity of feather moss associative N2-fixing cyanobacteria.2005Inngår i: Journal of Experimental Botany, ISSN 0022-0957, Vol. 56, nr 422, s. 3121-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cyanobacteria colonizing the feather moss Pleurozium schreberi were isolated from moss samples collected in northern Sweden and subjected to physiological and molecular characterization. Morphological studies of isolated and moss-associated cyanobacteria were carried out by light microscopy. Molecular tools were used for cyanobacteria identification, and a reconstitution experiment of the association between non-associative mosses and cyanobacteria was conducted. The influence of temperature on N2 fixation in the different cyanobacterial isolates and the influence of light and temperature on N2-fixation rates in the moss were studied using the acetylene reduction assay. Two different cyanobacteria were effectively isolated from P. schreberi: Nostoc sp. and Calothrix sp. A third genus, Stigonema sp. was identified by microscopy, but could not be isolated. The Nostoc sp. was found to fix N2 at lower temperatures than Calothrix sp. Nostoc sp. and Stigonema sp. were the predominant cyanobacteria colonizing the moss. The attempt to reconstitute the association between the moss and cyanobacteria was successful. The two isolated genera of cyanobacteria in feather moss samples collected in northern Sweden differ in their temperature optima, which may have important ecological implications.

  • 315.
    GEZEILUS, K
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    HALLGREN, JE
    EFFECT OF SO32- ON THE ACTIVITY OF RIBULOSE BISPHOSPHATE CARBOXYLASE FROM SEEDLINGS OF PINUS-SILVESTRIS1980Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 49, nr 4, s. 354-358Artikkel i tidsskrift (Fagfellevurdert)
  • 316.
    GEZELIUS, K
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    ERICSSON, A
    HALLGREN, JE
    BRUNES, L
    EFFECTS OF BUD REMOVAL IN SCOTS PINE (PINUS-SILVESTRIS) SEEDLINGS1981Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 51, nr 2, s. 181-188Artikkel i tidsskrift (Fagfellevurdert)
  • 317.
    GEZELIUS, K
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    FELTER, S
    STAHL, A
    STUDY ON POLYPHOSPHATES DURING MULTICELLULAR DEVELOPMENT OF DICTYOSTELIUM-DISCOIDEUM1973Inngår i: COMPTES RENDUS HEBDOMADAIRES DES SEANCES DE L ACADEMIE DES SCIENCES SERIE D, Vol. 276, nr 1, s. 117-119Artikkel i tidsskrift (Fagfellevurdert)
  • 318. Giacomello, Stefania
    et al.
    Salmen, Fredrik
    Terebieniec, Barbara K.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Vickovic, Sanja
    Navarro, José Fernandez
    Alexeyenko, Andrey
    Reimegard, Johan
    McKee, Lauren S.
    Mannapperuma, Chanaka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Bulone, Vincent
    Ståhl, Patrik L.
    Sundström, Jens F.
    Street, Nathaniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Lundeberg, Joakim
    Spatially resolved transcriptome profiling in model plant species2017Inngår i: Nature Plants, ISSN 2055-026X, Vol. 3, nr 6, artikkel-id 17061Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding complex biological systems requires functional characterization of specialized tissue domains. However, existing strategies for generating and analysing high-throughput spatial expression profiles were developed for a limited range of organisms, primarily mammals. Here we present the first available approach to generate and study highresolution, spatially resolved functional profiles in a broad range of model plant systems. Our process includes highthroughput spatial transcriptome profiling followed by spatial gene and pathway analyses. We first demonstrate the feasibility of the technique by generating spatial transcriptome profiles from model angiosperms and gymnosperms microsections. In Arabidopsis thaliana we use the spatial data to identify differences in expression levels of 141 genes and 189 pathways in eight inflorescence tissue domains. Our combined approach of spatial transcriptomics and functional profiling offers a powerful new strategy that can be applied to a broad range of plant species, and is an approach that will be pivotal to answering fundamental questions in developmental and evolutionary biology.

  • 319.
    Goretti, Daniela
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Department of Biosciences, University of Milan, Via Celoria 26, Milan, Italy.
    Martignago, Damiano
    Landini, Martina
    Brambilla, Vittoria
    Gomez-Ariza, Jorge
    Gnesutta, Nerina
    Galbiati, Francesca
    Collani, Silvio
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Takagi, Hiroki
    Terauchi, Ryohei
    Mantovani, Roberto
    Fornara, Fabio
    Transcriptional and Post-transcriptional Mechanisms Limit Heading Date 1 (Hd1) Function to Adapt Rice to High Latitudes2017Inngår i: PLoS Genetics, ISSN 1553-7390, E-ISSN 1553-7404, Vol. 13, nr 1, artikkel-id e1006530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rice flowering is controlled by changes in the photoperiod that promote the transition to the reproductive phase as days become shorter. Natural genetic variation for flowering time has been largely documented and has been instrumental to define the genetics of the photoperiodic pathway, as well as providing valuable material for artificial selection of varieties better adapted to local environments. We mined genetic variation in a collection of rice varieties highly adapted to European regions and isolated distinct variants of the long day repressor HEADING DATE 1 (Hd1) that perturb its expression or protein function. Specific variants allowed us to define novel features of the photoperiodic flowering pathway. We demonstrate that a histone fold domain scaffold formed by GRAIN YIELD, PLANT HEIGHT AND HEADING DATE 8 (Ghd8) and several NF-YC subunits can accommodate distinct proteins, including Hd1 and PSEUDO RESPONSE REGULATOR 37 (PRR37), and that the resulting OsNF-Y complex containing Hd1 can bind a specific sequence in the promoter of HEADING DATE 3A (Hd3a). Artificial selection has locally favored an Hd1 variant unable to assemble in such heterotrimeric complex. The causal polymorphism was defined as a single conserved lysine in the CCT domain of the Hd1 protein. Our results indicate how genetic variation can be stratified and explored at multiple levels, and how its description can contribute to the molecular understanding of basic developmental processes.

  • 320. Gough, Simon P
    et al.
    Rzeznicka, Kamila
    Peterson Wulff, Ragna
    Francisco, Jose da Cruz
    Hansson, Andreas
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik. Umeå Plant Science Centre.
    Jensen, Poul Erik
    Hansson, Mats
    A new method for isolating physiologically active Mg-protoporphyrin monomethyl ester, the substrate of the cyclase enzyme of the chlorophyll biosynthetic pathway.2007Inngår i: Plant Physiology and Biochemistry, ISSN 0981-9428, Vol. 45, nr 12, s. 932-6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mg-protoporphyrin monomethyl ester (MPE) is a biosynthetic intermediate of chlorophyll and converted by MPE cyclase to protochlorophyllide. Limited availability of MPE has so far hampered cyclase research. In a new, simplified, method MPE was prepared from freeze dried bchE mutant Rhodobacter capsulatus DB575 cells by extraction with acetone/H2O/25% NH3. Isolated MPE was identified by absorption and fluorescence spectroscopy, and its purity was analyzed by HPLC. The extracted MPE was dried and redissolved in buffered DMSO and its substrate activity is shown by enzymatic cyclase assays. A linear time course was observed for MPE conversion to protochlorophyllide by enzymes from barley etioplasts. Our innovation of freeze drying the R. capsulatus cells before extraction provides a high yield method for MPE, which is significantly faster and more reproducible than previous extraction methods.

  • 321. Goulas, Estelle
    et al.
    Schubert, Maria
    Kieselbach, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kleczkowski, Leszek
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Schröder, Wolfgang
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    The chloroplast lumen and stromal proteomes of Arabidopsis thaliana show differential sensitivity to short- and long-term exposure to low temperature.2006Inngår i: Plant Journal, ISSN 0960-7412, Vol. 47, nr 5, s. 720-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cold acclimation and over-wintering by herbaceous plants are energetically expensive and are dependent on functional plastid metabolism. To understand how the stroma and the lumen proteomes adapt to low temperatures, we have taken a proteomic approach (difference gel electrophoresis) to identify proteins that changed in abundance in Arabidopsis chloroplasts during cold shock (1 day), and short- (10 days) and long-term (40 days) acclimation to 5°C. We show that cold shock (1 day) results in minimal change in the plastid proteomes, while short-term (10 days) acclimation results in major changes in the stromal but few changes in the lumen proteome. Long-term acclimation (40 days) results in modulation of the proteomes of both compartments, with new proteins appearing in the lumen and further modulations in protein abundance occurring in the stroma. We identify 43 differentially displayed proteins that participate in photosynthesis, other plastid metabolic functions, hormone biosynthesis and stress sensing and signal transduction. These findings not only provide new insights into the cold response and acclimation of Arabidopsis, but also demonstrate the importance of studying changes in protein abundance within the relevant cellular compartment.

  • 322. Granado-Yela, C
    et al.
    García-Verdugo, C
    Carrillo, K
    Rubio DE Casas, R
    Kleczkowski, Leszek A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Balaguer, L
    Temporal matching among diurnal photosynthetic patterns within the crown of the evergreen sclerophyll Olea europaea L2011Inngår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 34, nr 5, s. 800-810Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Trees are modular organisms that adjust their within-crown morphology and physiology in response to within-crown light gradients. However, whether within-plant variation represents a strategy for optimizing light absorption has not been formally tested. We investigated the arrangement of the photosynthetic surface throughout one day and its effects on the photosynthetic process, at the most exposed and most sheltered crown layers of a wild olive tree (Olea europaea L.). Similar measurements were made for cuttings taken from this individual and grown in a greenhouse at contrasted irradiance-levels (100 and 20% full sunlight). Diurnal variations in light interception, carbon fixation and carbohydrate accumulation in sun leaves were negatively correlated with those in shade leaves under field conditions when light intensity was not limiting. Despite genetic identity, these complementary patterns were not found in plants grown in the greenhouse. The temporal disparity among crown positions derived from specialization of the photosynthetic behaviour at different functional and spatial scales: architectural structure (crown level) and carbon budget (leaf level). Our results suggest that the profitability of producing a new module may not only respond to construction costs or light availability, but also rely on its spatio-temporal integration within the productive processes at the whole-crown level.

  • 323.
    Granlund, Irene
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Proteomic analysis of Arabidopsis thaliana2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A complete proteome analysis of the chloroplast stroma, using 2D-PAGE, from spinach and Arabidopsis was performed. To improve the identification of proteins a computer program named SPECLUST was used. In SPECLUST, peak masses that are similar in many spots cluster together because they originate from the same protein with different locations on the gel. Within this program peaks in a cluster can be investigated in detail by peaks-in-common, and the unidentified masses that differ between spots in a cluster could be caused by protein modifications, which was analysed further by MS/MS.

    The thylakoid is an internal membrane system in the chloroplast where protein complexes involved in photosynthesis are housed. Enclosed in the thylakoid membrane is the chloroplast lumen, with a proteome estimated to contain 80-200 different proteins. Because the chloroplast lumen is close to the photosynthesis machinery in the plant, one can expect that the lumen proteome will change depending on if the plant is dark or light adapted. DIGE analysis of lumen proteins found that 15 lumen proteins show increased relative abundance in light-adapted plants. In addition co-expression analysis of lumen protein genes suggests that the lumen protein genes are uniformly transcriptionally regulated, not only by light but in a general manner.

    Plastocyanin is one of the proteins involved in the electron transfer in photosynthesis. Two homologous plastocyanin isoforms are encoded by the genes PETE1 and PETE2 in the nuclear genome of Arabidopsis, where PETE2 is the more abundant isoform. Knockout mutants of each of the plastocyanin isoforms shows that a 90% reduction of plastocyanin levels affects rates of photosynthesis and growth only slightly. A corresponding over-expression of plastocyanin in each of the two knockout mutants results in essentially wild-type photosynthetic performance. Reduced plastocyanin levels make the plant sensitive to Cu stress and therefore plastocyanin plays a major role as a Cu sink.

    A by-product of photosynthesis is hydrogen peroxide, which may be harmful for the plant. The discovery that an abundant protein found in the chloroplast lumen, TL29, shared sequence homology to Ascorbate Peroxidase (APX) was therefore of interest. We have evidence that TL29 is not an APX protein; it lacks the heme-binding active site and shows no activity. TL29 is located in the grana region and is electrostaticaly attached to the thylakoid membrane. It has four isoforms, with different pIs, both in the native and denatured form. It has no interaction with ascorbate, when compared to raAPX1. TL29 has two cysteine residues and one of them seems to have redox-regulated function, proposing that it may interact with other proteins close to PSII.

  • 324.
    Gratz, Regina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Expression Studies of AminoAcid Transporters belonging to the Lysine and Hisitidine Transporter (LHT) Family in Hybrid Aspen Populus tremula L. x tremuloides Michx.2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The human based input of fixed nitrogen, e.g. due to nitrogenous fertilizers, is the second most important driver of global change. The active input was, however, necessary due to a fast growing demand for agricultural products in order to feed an expanding world population in the last decades. Severe environmental damages are visible now, which is why it is crucial to find alternative ways to increase plant growth and biomass production without applying massive amounts of fertilizers. One way is to identify genes, which are able to improve nitrogen use efficiency (NUE) in plants when manipulated. Especially genes involved in nitrogen uptake, assimilation and remobilization, such as amino acid transporters are of great interest. Therefore a detailed knowledge about molecular processes regarding nitrogen transport in the respective plant species is crucial. So far, there is not much known about amino acid uptake mechanisms in tree species, which is why this work focuses on hybrid aspen. It was aimed to investigate the tissue expression patterns of genes encoding putative amino acid transporters in order to find potential target genes for improving NUE in the long term.

    It was shown that eight homologs of a main Arabidopsis amino acid transporter, AtLHT1, are expressed in poplar. The eight amino acid transporters displayed different expression patterns, with expression in roots, stem and leaves of young hybrid aspen. To analyze the impacts of an increased amino acid uptake phenotype in a tree model system, PtLHT1.2 was cloned into an expression vector for Agrobacterium-mediated transformation into hybrid aspen. These results will be of great value for further studies regarding NUE in tree models.

  • 325.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Cell polarity: lateral perspectives2010Inngår i: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 20, nr 10, s. R446-R448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The outer and inner (lateral) plasma membranes of the outermost cell layer in plants provide selective barriers to the environment. Recent studies provide perspectives on how asymmetric protein localization is established at lateral membranes.

  • 326.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Out of the shade and into the light2011Inngår i: Nature Cell Biology, ISSN 1465-7392, E-ISSN 1476-4679, Vol. 13, nr 4, s. 347-349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Plants reach for the sun by avoiding the shade and by directly growing towards the light. Two studies now suggest that the polar relocation of PIN3, a transporter directing the flow of the plant hormone auxin, drives both growth processes. PIN3 repolarization occurs downstream of shade perception through phytochrome photoreceptors, whereas blue light perceived by phototropin initiates polar recycling of PIN3 and growth towards the light.

  • 327.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Plant biology: Unveiling the Casparian strip.2011Inngår i: Nature, ISSN 1476-4687, Vol. 473, nr 7347, s. 294-5Artikkel i tidsskrift (Fagfellevurdert)
  • 328.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    The patterning of epidermal hairs in Arabidopsis: updated2012Inngår i: Current opinion in plant biology, ISSN 1369-5266, E-ISSN 1879-0356, Vol. 15, nr 1, s. 31-37Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Epidermal hairs of Arabidopsis thaliana emerge in regular spacing patterns providing excellent model systems for studies of biological pattern formation. A number of root-hair and leaf-trichome patterning mutants and tools for cell-specific and tissue-specific manipulation of patterning protein activities have been combined in cycles of experimentation and mathematical modelling. These approaches have provided insight into molecular mechanisms of epidermal patterning. During the last two years, endoreplication has, unexpectedly, been found to control cell-fate maintenance during trichome patterning. New genetic interactions between a downstream, positive transcriptional regulator and lateral inhibitors of trichome or non-root-hair fate specification have been uncovered. A lateral inhibitor and a new positive regulator have been identified as major loci affecting trichome patterning in natural Arabidopsis populations. Finally, factors that modify root-hair patterning from the underlying cell layer have been discovered.

  • 329. Grebe, Steffen
    et al.
    Trotta, Andrea
    Bajwa, Azfar A.
    Suorsa, Marjaana
    Gollan, Peter J.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Tikkanen, Mikko
    Aro, Eva-Mari
    The unique photosynthetic apparatus of Pinaceae: analysis of photosynthetic complexes in Picea abies2019Inngår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 70, nr 12, s. 3211-3225Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pinaceae are the predominant photosynthetic species in boreal forests, but so far no detailed description of the protein components of the photosynthetic apparatus of these gymnosperms has been available. In this study we report a detailed characterization of the thylakoid photosynthetic machinery of Norway spruce (Picea abies (L.) Karst). We first customized a spruce thylakoid protein database from translated transcript sequences combined with existing protein sequences derived from gene models, which enabled reliable tandem mass spectrometry identification of P. abies thylakoid proteins from two-dimensional large pore blue-native/SDS-PAGE. This allowed a direct comparison of the two-dimensional protein map of thylakoid protein complexes from P. abies with the model angiosperm Arabidopsis thaliana. Although the subunit composition of P. abies core PSI and PSII complexes is largely similar to that of Arabidopsis, there was a high abundance of a smaller PSI subcomplex, closely resembling the assembly intermediate PSI* complex. In addition, the evolutionary distribution of light-harvesting complex (LHC) family members of Pinaceae was compared in silico with other land plants, revealing that P. abies and other Pinaceae (also Gnetaceae and Welwitschiaceae) have lost LHCB4, but retained LHCB8 (formerly called LHCB4.3). The findings reported here show the composition of the photosynthetic apparatus of P. abies and other Pinaceae members to be unique among land plants.

  • 330. Greer, DH
    et al.
    Ottander, Christina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Photoinhibition and recovery of photosynthesis in intact barley leaves at 5 and 20°C1991Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 81, nr 2, s. 203-210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoinhibition of photosynthesis and its recovery were studied in intact barley (Hordeum vulgare L. cv. Gunilla) leaves grown in a controlled environment by exposing them to two temperatures, 5 and 20-degrees-C, and a range of photon flux densities in excess of that during growth. Additionally, photoinhibition was examined in the presence of chloramphenicol (CAP, an inhibitor of chloroplast protein synthesis) and of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Susceptibility to photoinhibition was much higher at 5 than at 20-degrees-C. Furthermore, at 20-degrees-C CAP exacerbated photoinhibition strongly, whereas CAP had little additional effect (10%) at 5-degrees-C. These results support the model that net photoinhibition is the difference between the inactivation and repair of photosystem II (PSII); i.e. the degradation and synthesis of the reaction centre protein, D1. Furthermore, the steady-state extent of photoinhibition was strongly dependent on temperature and the results indicated this was manifested through the effects of temperature on the repair process of PSII. We propose that the continuous repair of PSII at 20-degrees-C conferred at least some protection from photoinhibition. At 5-degrees-C the repair process was largely inhibited, with increased photoinhibition as a consequence. However, we suggest where repair is inhibited by low temperature, some protection is alternatively conferred by the photoinhibited reaction centres. Providing they are not degraded, such centres could still dissipate excitation energy non-radiatively, thereby conferring protection of remaining photochemically active centres under steady-state conditions. A fraction of PS II centres were capable of resisting photoinhibition when the repair process was inhibited by CAP. This is discussed in relation to PS II heterogeneity. Furthermore, the repair process was not apparently activated within 3 h when barley leaves were transferred to photoinhibitory light conditions at 20-degrees-C.

  • 331. Grimberg, Åsa
    et al.
    Lager, Ida
    Street, Nathaniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Robinson, Kathryn M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Marttila, Salla
    Mähler, Niklas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Ingvarsson, Pär K.
    Bhalerao, Rishikesh P.
    Storage lipid accumulation is controlled by photoperiodic signal acting via regulators of growth cessation and dormancy in hybrid aspen2018Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 219, nr 2, s. 619-630Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The signalling pathways that control seasonal modulation of carbon metabolism in perennial plants are poorly understood. Using genetic, metabolic and natural variation approaches, we identify factors mediating photoperiodic control of storage lipid accumulation in the model tree hybrid aspen (Populus tremula x tremuloides). We characterized lipid accumulation in transgenic hybrid aspen with impaired photoperiodic and hormonal responses. Genome-wide association mapping was performed in Swedish aspen (P.tremula) genotypes to determine genetic loci associated with genotype variation in lipid content. Our data show that the storage lipid triacylglycerol (TAG) accumulates in cambial meristem and pith rays of aspen in response to photoperiodic signal controlling growth cessation and dormancy induction. We show that photoperiodic control of TAG accumulation is mediated by the FLOWERING LOCUS T/CONSTANS module, which also controls the induction of growth cessation. Hormonal and chromatin remodelling pathways also contribute to TAG accumulation by photoperiodic signal. Natural variation exists in lipid accumulation that is controlled by input from multiple loci. Our data shed light on how the control of storage metabolism is temporally coordinated with growth cessation and dormancy by photoperiodic signal, and reveals that storage lipid accumulation between seeds and perennating organs of trees may involve distinct regulatory circuits.

  • 332. Grivel, J-C
    et al.
    Pitillas, A.
    Namazkar, S.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Department of Energy Conversion and Storage, Technical University of Denmark, 4000-Roskilde, Denmark.
    Alexiou, A.
    Holte, O. J.
    Preparation and characterization of MgB2 with Pd, Pt and Re doping2016Inngår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 520, s. 37-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Samples with Mg1-xDxB2.04 (D = Pt, Pd or Re) nominal compositions have been synthesised by a solid-state route. None of these doping elements can be substituted for Mg in a detectable amount and their presence in the samples has no influence on the critical temperature and on the lattice parameters of the MgB2 superconductor. Impurity phases are formed by reaction mostly with Mg. The microstructure of the Pt, Pd and Re-based phases depends on the elements. Re-rich particles with large sizes up to 8 mu m form, whereas Pt- and Pd-containing impurities are finely dispersed with a particle size that does not exceed 1 mu m. The field dependence of the normalised critical current density is improved when Pt, Pd or Re are present in the samples. (C) 2015 Elsevier B.V. All rights reserved.

  • 333.
    Grönlund, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Bhalerao, Rishikesh P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Modular gene expression in Poplar: a multilayer network approach2009Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 181, nr 2, s. 315-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    * By applying a multilayer network approach to an extensive set of Poplar microarray data, a genome-wide coexpression network has been detected and explored.

    * Multilayer networks were generated from minimum spanning trees (MSTs) using Kruskal's algorithm from random jack-knife resamplings of half of the full data set. The final network is obtained from the union of all the generated MSTs.

    * The gene expression correlations display a highly clustered topology, which is more pronounced when introducing links appearing in relatively few of the generated MSTs. The network also reveals a modular architecture, reflecting functional groups with relatively frequent gene-to-gene communication. Furthermore, the observed modular structure overlaps with different gene activities in different tissues, and closely related tissues show similar over- and/or under-expression patterns at the modular scale.

    * It is shown that including links that appear in a few of the generated MSTs increases the information quality of the network. In other words, a link may be 'weak' because it reflects rare signaling events rather than merely a signal weakened by noise. The method allows, from comparisons of random 'null networks', tuning to maximize the information obtainable.

  • 334.
    Grönlund, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Holme, Petter
    Minnhagen, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Dynamic scaling regimes of collective decision making2008Inngår i: EPL - Europhysics Letters, Vol. 81, nr 2, s. 28003-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate a social system of agents faced with a binary choice. We assume there is a correct, or beneficial, outcome of this choice. Furthermore, we assume agents are influenced by others in making their decision, and that the agents can obtain information that may guide them towards making a correct decision. The dynamic model we propose is of nonequilibrium type, converging to a final decision. We run it on random graphs and scale-free networks. On random graphs, we find two distinct regions in terms of the finalizing time —the time until all agents have finalized their decisions. On scale-free networks, on the other hand, there do not seem to be such distinct scaling regions.

  • 335.
    Grönlund, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Lötstedt, Per
    Elf, Johan
    Transcription factor binding kinetics constrain noise suppression via negative feedback2013Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 4, s. 1864-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Negative autoregulation, where a transcription factor regulates its own expression by preventing transcription, is commonly used to suppress fluctuations in gene expression. Recent single molecule in vivo imaging has shown that it takes significant time for a transcription factor molecule to bind its chromosomal binding site. Given the slow association kinetics, transcription factor mediated feedback cannot at the same time be fast and strong. Here we show that with a limited association rate follows an optimal transcription factor binding strength where noise is maximally suppressed. At the optimal binding strength the binding site is free a fixed fraction of the time independent of the transcription factor concentration. One consequence is that high-copy number transcription factors should bind weakly to their operators, which is observed for transcription factors in Escherichia coli. The results demonstrate that a binding site's strength may be uncorrelated to its functional importance.

  • 336. Gundale, Michael J.
    et al.
    Sverker, Jennie
    Albrectsen, Benedicte R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Nilsson, Marie-Charlotte
    Wardle, David A.
    Variation in protein complexation capacity among and within six plant species across a boreal forest chronosequence2010Inngår i: Plant Ecology, ISSN 1385-0237, E-ISSN 1573-5052, Vol. 211, nr 2, s. 253-266Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated among and within species variation in several litter chemical properties, including protein complexation capacity (PCC), for six plant species across a boreal forest chronosequence in northern Sweden across which stand fertility declines sharply with stand age. We hypothesized (1) that evergreen species which dominate in late-successional stands would exhibit higher PCCs than deciduous species that dominate in young stands, (2) that individual species would increase their PCCs in response to nutrient limitation as succession proceeds, and (3) that differences in PCC among litter types would determine their interactive effects with proteins on soil N and C mineralization. The data demonstrated a high PCC, but a low PCC per unit of soluble phenol, for two deciduous species that dominate in early-successional high fertility stands, providing mixed support for our first hypothesis. No species demonstrated a significant correlation between their PCC and stand age, which did not support our second hypothesis. Finally, a soil incubation assay revealed that litter extracts for three of the six species had negative interactive effects with added proteins on N mineralization rates, and that all six species demonstrated positive interactive effects with protein on C mineralization. This pattern did not provide strong support for our third hypothesis, and suggests that N immobilization was likely a more important factor regulating N mineralization than stabilization of proteins into tannin complexes. These data suggest that multiple interactive mechanisms between litter extracts and proteins likely occur simultaneously to influence the availability of N in soils.

  • 337. GUSTAFSSON, L
    et al.
    Gustafsson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    LOW GENETIC-VARIATION IN SWEDISH POPULATIONS OF THE RARE SPECIES VICIA-PISIFORMIS (FABACEAE) REVEALED WITH RFLP (RDNA) AND RAPD1994Inngår i: Plant Systematics and Evolution, ISSN 0378-2697, E-ISSN 1615-6110, Vol. 189, nr 3-4, s. 133-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nine Swedish populations, 1-5 individuals/population, and one cultivated individual of the rare species Vicia pisiformis were investigated for genetic variation. In hybridizations with two rDNA probes using 8 restriction enzymes, only two individuals belonging to one population were polymorphic. A map of the rDNA gene cluster was constructed for four of the restriction enzymes used. Two of the polymorphic sites were mapped and were found to be located outside regions coding for rRNA, presumably caused by single point mutations or small deletions. The repeat length of the rDNA region was c. 10,000 bp, which corresponds well with the size found for other species belonging to Fabaceae. No length polymorphism was found in the intergenic spacer, contrary to the situation found for most other plant species investigated for rDNA variation. The haplotype diversity for the species (Hsp Shannon) was very low (0.055). Within-population values (Hpop) was 0 for all populations except the variable one, which had 0.301. PCR amplification with 6 random primers also revealed very low levels of genetic diversity. A polymorphism was observed in a limited number of individuals for four populations. Hsp was 0.065 and HpopBAR was 0.050. The average D value (Wetton) for the PCR haplotypes was 0.99.

  • 338.
    Gustafsson, Petter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    LIDHOLM, J
    LUNDBERG, AK
    STRUCTURE AND REGULATION OF PHOTOSYNTHESIS GENES IN PINUS-SYLVESTRIS (SCOTS PINE) AND PINUS-CONTORTA (LODGEPOLE PINE)1991Inngår i: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 43, nr 3-4, s. 287-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure and regulation of one nuclear and one chloroplast gene was studied in Pinus sylvestris (Scots pine) and Pinus contorta (lodgepole pine). cDNA copies of the nuclear located cab genes of Pinus sylvestris, coding for the light-harvesting chlorophyll a/b-binding proteins of photosystem II (LHC-II), were cloned. cab-II genes coding for both types of LHC-II polypeptides, Types 1 and 2, were found. An analysis of the DNA sequences of several different cab-II cDNAs shows that they have a high bias for the nucleotides G and C at the third base positions of the codons, making them more similar to monocot than to dicot genes. Two of the three genes were found to be located within CpG islands. The cab-II genes were found to be expressed in dark-grown seedlings in contrast to what has been found for most angiosperms. The chloroplast genomes of conifers were shown to lack the inverted repeat organization normally found in higher plants, mosses and green algae. The psbA gene, located in the chloroplast genome and coding for the D1 polypeptide in the reaction center of photosystem II, was found to be tandemly duplicated in P. contorta. Cloning and sequence analysis of the two psbA genes and the surrounding regions showed that the duplicated segment is 1.97 kb long and that it ends 19 bp downstream from the psbA stop codon. The corresponding locus of P. sylvestris, which lacks the duplication, was cloned and characterized. A comparison with P. contorta indicates how the duplication/insertion event has occurred. A comparison of third codon position between P. contorta psbA and that of other plants indicated an almost equidistant evolutionary relationship between P. contorta, spinach (or barley) and Marchantia polymorpha.

  • 339. Guy, Charles
    et al.
    Porat, Ron
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Plant cold and abiotic stress gets hot2006Inngår i: Physiologia Plantarum, Vol. 126, s. 1-4Artikkel i tidsskrift (Fagfellevurdert)
  • 340.
    Haas, Julia Christa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Abiotic stress and plant-microbe interactions in Norway spruce2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Norway spruce (Picea abies) is a dominant tree species in boreal forests with extensive ecological and economic value. Climate change is threatening these ecosystems, with rising temperatures impacting cold hardening and increasing drought stress in regions experiencing lower precipitation. Increasing atmospheric CO2 concentrations and nitrogen deposition can, in contrast, partially offset such negative effects by improving tree growth and carbon uptake. Similar to aboveground carbon fixation, carbon sequestration in boreal soils is important. Bacteria and fungi mineralize organic matter and, by making nutrients available for plants, are important for tree health. The ability of Norway spruce and the associated microbiota to adapt to climate change is of fundamental importance for ecosystem functioning and is the focus of this thesis.

    Norway spruce seedlings were subjected to cold or drought stress and the transcriptional response compared to known mechanisms in the model plant Arabidopsis thaliana. Analyses revealed that while there was overlap in the stress responses between species, including increased osmotic and oxidative stress tolerance, the majority of differentially expressed genes were stress-responsive only in Norway spruce. Importantly, transcription factors of the abscisic acid dependent and independent pathways were not differentially expressed or were missing homolog sequences in Norway spruce, indicating that different regulatory pathways are active in Norway spruce and suggesting that stress response has evolved differently in the species. Furthermore, differential gene expression in roots differed extensively from that of needles in response to stress and highlighted the need for separate profiling in above- and belowground tissues.

    In another study at the Flakaliden research site in northern Sweden, the effects of long-term nutrient addition on the microbiota associated with mature Norway spruce were tested. In agreement with earlier findings, nutrient addition improved tree growth and phylogenetic marker gene analysis on DNA of fungi and bacteria provided new insights into associated changes in plant-microbe interactions. Microbial diversity increased over time and compositional changes in nitrophilic community members indicated changes in carbon and nitrogen cycling at the plant-microbe interface, which has implications for carbon storage in boreal forest soils in the future. Follow-up RNA-based techniques largely confirmed community members from marker gene analysis.

    In summary, understanding of both the Norway spruce-specific responses to abiotic stress and the ability of the associated microbiota to cope with the environmental changes are essential for future productivity, survival and distribution of Norway spruce forests. Sustainability will depend on tree vitality and a more holistic understanding of tree-microbe interactions is required to model future sustainability.

  • 341.
    Haas, Julia Christa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Street, Nathaniel R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sjödin, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Division of CBRN Security and Defence, FOI–Swedish Defence Research Agency, Umeå, Sweden.
    Lee, Natuschka M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Högberg, Mona N.
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Näsholm, Torgny
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden; Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, SLU, Umeå, Sweden.
    Hurry, Vaughan
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, SLU, Umeå, Sweden.
    Microbial community response to growing season and plant nutrient optimisation in a boreal Norway spruce forest2018Inngår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 125, s. 197-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Interactions between Norway spruce trees and bacteria and fungi in nutrient limited boreal forests can be beneficial for tree growth and fitness. Tree-level effects of anthropogenic nutrient addition have been well studied, however understanding of the long-term effects on the associated microbiota is limited. Here, we report on the sensitivity of microbial community composition to the growing season and nutrient additions. Highthroughput sequencing of the bacterial 16S rRNA gene and fungal ITS1 region was used to characterise changes in the microbial community after application of a complete mineral nutrient mixture for five and 25 years. The experiment was conducted using the Flakaliden forest research site in northern boreal Sweden and included naturally low nutrient control plots. Needle and fine root samples of Norway spruce were sampled in addition to bulk soil during one growing season to provide comprehensive insight into phyllosphere and belowground microbiota community changes. The phyllosphere microbiota was compositionally distinct from the belowground communities and phyllosphere diversity increased significantly over the growing season but was not influenced by the improved nutrient status of the trees. In both root and soil samples, alpha diversity of fungal, in particular ectomycorrhizal fungi (EMF), and bacterial communities increased after long-term nutrient optimisation, and with increasing years of treatment the composition of the fungal and bacterial communities changed toward a community with a higher relative abundance of nitrophilic EMF and bacterial species but did not cause complete loss of nitrophobic species from the ecosystem. From this, we conclude that 25 years of continuous nutrient addition to a boreal spruce stand increased phylotype richness and diversity of the microbiota in the soil, and at the root-soil interface, suggesting that long-term anthropogenic nutrient inputs can have positive effects on belowground biodiversity that may enhance ecosystem robustness. Future studies are needed to assess the impact of these changes to the microbiota on ecosystem carbon storage and nitrogen cycling in boreal forests.

  • 342.
    Haas, Julia Christa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Vergara, Alexander
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Hurry, Vaughan
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Street, Nathaniel Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Candidate regulators and target genes of drought-stress in needles and roots of Norway spruceManuskript (preprint) (Annet vitenskapelig)
  • 343.
    Hall, David
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Luquez, Virginia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Garcia, Maribel Victoria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    St Onge, Kate R
    Department of Evolutionary Functional Genomics, Evolutionary Biology Centre, Uppsala University, Sweden.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Ingvarsson, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Adaptive population differentiation in phenology across a latitudinal gradient in European aspen (Populus tremula, L.): a comparison of neutral markers, candidate genes and phenotypic traits2007Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 61, s. 2849-2860Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A correct timing of growth cessation and dormancy induction represents a critical ecological and evolutionary trade-off between survival and growth in most forest trees (Rehfeldt et al. 1999; Horvath et al. 2003; Howe et al. 2003). We have studied the deciduous tree European Aspen (Populus tremula) across a latitudinal gradient and compared genetic differentiation in phenology traits with molecular markers. Trees from 12 different areas covering 10 latitudinal degrees were cloned and planted in two common gardens. Several phenology traits showed strong genetic differentiation and clinal variation across the latitudinal gradient, with QST values generally exceeding 0.5. This is in stark contrast to genetic differentiation at several classes of genetic markers (18 neutral SSRs, 7 SSRs located close to phenology candidate genes and 50 SNPs from five phenology candidate genes) that all showed FST values around 0.015. We thus find strong evidence for adaptive divergence in phenology traits across the latitudinal gradient. However, the strong population structure seen at the quantitative traits is not reflected in underlying candidate genes. This result fit theoretical expectations that suggest that genetic differentiation at candidate loci is better described by FST at neutral loci rather than by QST at the quantitative traits themselves.

  • 344.
    Hall, Michael
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mishra, Yogesh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Schröder, Wolfgang P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Preparation of stroma, thylakoid membrane, and lumen fractions from arabidopsis thaliana chloroplasts for proteomic analysis2011Inngår i: In Chloroplast Research in Arabidopsis: Methods and Protocols, Volume II. R. / [ed] Paul Jarvis, Springer Science + Business Media, LLC 2011 , 2011, Vol. 775, nr 3, s. 207-222Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    For many studies regarding important chloroplast processes such as oxygenic photosynthesis, fractionation of the total chloroplast proteome is a necessary first step. Here, we describe a method for isolating the stromal, the thylakoid membrane, and the thylakoid lumen subchloroplast fractions from Arabidopsis thaliana leaf material. All three fractions can be isolated sequentially from the same plant material in a single day preparation. The isolated fractions are suitable for various proteomic analyses such as simple mapping studies or for more complex experiments such as differential expression analysis using two-dimensional difference gel electrophoresis (2D-DIGE) or mass spectrometry (MS)-based techniques. Besides this, the obtained fractions can also be used for many other purposes such as immunological assays, enzymatic activity assays, and studies of protein complexes by native-polyacrylamide gel electrophoresis (native-PAGE).

  • 345.
    HALLGREN, JE
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    FREDRIKSSON, SA
    EMISSION OF HYDROGEN-SULFIDE FROM SULFUR-DIOXIDE FUMIGATED PINE TREES1982Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 70, nr 2, s. 456-459Artikkel i tidsskrift (Fagfellevurdert)
  • 346.
    HALLGREN, JE
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    GEZELIUS, K
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    EFFECTS OF SO2 ON PHOTOSYNTHESIS AND RIBULOSE BISPHOSPHATE CARBOXYLASE IN PINE TREE SEEDLINGS1982Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 54, nr 2, s. 153-161Artikkel i tidsskrift (Fagfellevurdert)
  • 347. HALLGREN, JE
    et al.
    LINDER, S
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    RICHTER, A
    TROENG, E
    GRANAT, L
    UPTAKE OF SO2 IN SHOOTS OF SCOTS PINE - FIELD-MEASUREMENTS OF NET FLUX OF SULFUR IN RELATION TO STOMATAL CONDUCTANCE1982Inngår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 5, nr 1, s. 75-83Artikkel i tidsskrift (Fagfellevurdert)
  • 348.
    HALLGREN, JE
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    SUNDBOM, E
    STRAND, M
    PHOTOSYNTHETIC RESPONSES TO LOW-TEMPERATURE IN BETULA-PUBESCENS AND BETULA-TORTUOSA1982Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 54, nr 3, s. 275-282Artikkel i tidsskrift (Fagfellevurdert)
  • 349. Halperin, Tami
    et al.
    Zheng, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Itzhaki, Hanan
    Clarke, Adrian
    Adam, Zach
    Plant mitochondria contain proteolytic and regulatory subunits of the ATP-dependent Clp protease2001Inngår i: Plant Molecular Biology, Vol. 45, nr 4, s. 461-468Artikkel i tidsskrift (Fagfellevurdert)
  • 350. Hankamer, B
    et al.
    Nield, J
    Zheleva, D
    Boekema, E
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Barber, J
    Isolation and biochemical characterisation of monomeric and dimeric photosystem II complexes from spinach and their relevance to the organisation of photosystem II in vivo1997Inngår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 243, nr 1-2, s. 422-429Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Membranes enriched in photosystem II were isolated from spinach and further solubilised using n-octyl beta-D-glucopyranoside (OctGlc) and n-dodecyl beta-D-maltoside (DodGlc(2)). The OctGlc preparation had high rates of oxygen evolution and when subjected to size-exclusion HPLC and sucrose density gradient centrifugation, in the presence of DodGlc(2), separated into dimeric (430 kDa), monomeric (236 kDa) photosystem II cores and a fraction containing photosystem II light-harvesting complex (Lhcb) proteins. The dimeric core fraction was more stable, contained higher levels of chlorophyll, beta-carotene and plastoquinone per photosystem II reaction centre and had a higher oxygen-evolving activity than the monomeric cores. Their subunit composition was similar (CP43, CP47, D1, D2, cytochrome b 559 and several lower-molecular-mass components) except that the level of 33-kDa extrinsic protein was lower in the monomeric fraction. Direct solubilisation of photosystem-II-enriched membranes with DodGlc(2), followed by sucrose density gradient centrifugation, yielded a super complex (700 kDa) containing the dimeric form of the photosystem II core and Lhcb proteins: Lhcb1, Lhcb2, Lhcb4 (CP29), and Lhcb5 (CP26). Like the dimeric and monomeric photosystem II core complexes, the photosystem II-LHCII complex had lost the 23-kDa and 17-kDa extrinsic proteins, but maintained the 33-kDa protein and the ability to evolve oxygen. It is suggested, with a proposed model, that the isolated photosystem II-LHCII super complex represents an in vivo organisation that can sometimes form a lattice in granal membranes of the type detected by freeze-etch electron microscopy [Seibert, M., DeWit, M. & Staehelin, L. A. (1987) J. Cell Biol. 105, 2257-2265].

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