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  • 201. Edvardsson, Anna
    et al.
    Shapiguzov, Alexey
    Petersson, Ulrika A
    Schröder, Wolfgang
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi. Umeå Plant Science Centre.
    Vener, Alexander V
    Immunophilin AtFKBP13 Sustains All Peptidyl-Prolyl Isomerase Activity in the Thylakoid Lumen from Arabidopsis thaliana Deficient in AtCYP20-22007Inngår i: Biochemistry, Vol. 46, nr 33, s. 9432-42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The physiological roles of immunophilins are unclear, but many possess peptidyl-prolyl isomerase (PPIase) activity, and they have been found in all organisms examined to date, implying that they are involved in fundamental, protein-folding processes. The chloroplast thylakoid lumen of the higher plant Arabidopsis thaliana contains up to 16 immunophilins (five cyclophilins and 11 FKBPs), but only two of them, AtCYP20-2 and AtFKBP13, have been found to be active PPIases, indicating that the other immunophilins in this cellular compartment may have lost their putative PPIase activities. To assess this possibility, we characterized two independent Arabidopsis knockout lines lacking AtCYP20-2 in enzymological and quantitative proteomic analyses. The PPIase activity in thylakoid lumen preparations of both mutants was equal to that of corresponding wild-type preparations, and comparative two-dimensional difference gel electrophoresis analyses of the lumenal proteins of the mutants and wild type showed that none of the potential PPIases was more abundant in the AtCYP20-2 deficient plants. Enzymatic analyses established that all PPIase activity in the mutant thylakoid lumen was attributable to AtFKBP13, and oxidative activation of this enzyme compensated for the lack of AtCYP20-2. Accordingly, sequence analyses of the potential catalytic domains of lumenal cyclophilins and FKBPs demonstrated that only AtCYP20-2 and AtFKBP13 possess all of the amino acid residues found to be essential for PPIase activity in earlier studies of human cyclophilin A and FKBP12. Thus, none of the immunophilins in the chloroplast thylakoid lumen of Arabidopsis except AtCYP20-2 and AtFKBP13 appear to possess prolyl isomerase activity toward peptide substrates.

  • 202. EDWARDS, GE
    et al.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ISOLATION OF MITOCHONDRIA FROM LEAVES OF C-3, C-4, AND CRASSULACEAN ACID METABOLISM PLANTS1987Inngår i: Methods in Enzymology, ISSN 0076-6879, E-ISSN 1557-7988, Vol. 148, s. 421-433Artikkel i tidsskrift (Fagfellevurdert)
  • 203. Edwards, Kieron D.
    et al.
    Takata, Naoki
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Johansson, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). RNA Biology and Molecular Physiology, Bielefeld University, Bielefeld, Germany.
    Jurca, Manuela
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Novak, Ondrej
    Henykova, Eva
    Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Liverani, Silvia
    Kozarewa, Iwanka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Strnad, Miroslav
    Millar, Andrew J.
    Ljung, Karin
    Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Eriksson, Maria E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Circadian clock components control daily growth activities by modulating cytokinin levels and cell division-associated gene expression in Populus trees2018Inngår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 41, nr 6, s. 1468-1482Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Trees are carbon dioxide sinks and major producers of terrestrial biomass with distinct seasonal growth patterns. Circadian clocks enable the coordination of physiological and biochemical temporal activities, optimally regulating multiple traits including growth. To dissect the clock's role in growth, we analysed Populus tremula x P. tremuloides trees with impaired clock function due to down-regulation of central clock components. late elongated hypocotyl (lhy-10) trees, in which expression of LHY1 and LHY2 is reduced by RNAi, have a short free-running period and show disrupted temporal regulation of gene expression and reduced growth, producing 30-40% less biomass than wild-type trees. Genes important in growth regulation were expressed with an earlier phase in lhy-10, and CYCLIN D3 expression was misaligned and arrhythmic. Levels of cytokinins were lower in lhy-10 trees, which also showed a change in the time of peak expression of genes associated with cell division and growth. However, auxin levels were not altered in lhy-10 trees, and the size of the lignification zone in the stem showed a relative increase. The reduced growth rate and anatomical features of lhy-10 trees were mainly caused by misregulation of cell division, which may have resulted from impaired clock function.

  • 204. Eimert, K
    et al.
    Luo, C
    Dejardin, A
    Villand, P
    Thorbjornsen, T
    Kleczkowski, Leszek A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Molecular cloning and expression of the large subunit of ADP-glucose pyrophosphorylase from barley (Hordeum vulgare) leaves1997Inngår i: Gene, ISSN 0378-1119, E-ISSN 1879-0038, Vol. 189, nr 1, s. 79-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A cDNA clone, blpl14, corresponding to the large subunit of ADP-glucose pyrophosphorylase (AGPase), has been isolated from a cDNA library prepared from leaves of barley (Hordeum vulgare L.). An open reading frame encodes a protein of 503 aa, with a calculated molecular weight of 54 815. The derived aa sequence contains a putative transit peptide sequence, required for targeting to plastids, and has a highly conserved positioning of critical Lys residues that are believed to be involved in effector binding. The derived aa sequence shows 97% identity with the corresponding protein from wheat, but only 36% identity with AGPase from E. coli. The blpl14 gene is expressed predominantly in leaves and to a lesser degree in seed endosperm, but not roots, of barley.

  • 205. Eimert, K
    et al.
    Villand, P
    Kilian, A
    Kleczkowski, Leszek A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Cloning and characterization of several cDNAs for UDP-glucose pyrophosphorylase from barley (Hordeum vulgare) tissues1996Inngår i: Gene, ISSN 0378-1119, E-ISSN 1879-0038, Vol. 170, nr 2, s. 227-232Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eleven cDNA clones encoding UDP-glucose pyrophosphorylase (UGPase) have been isolated from cDNA libraries prepared from seed embryo, seed endosperm and leaves of barley (Hordeum vulgare L.). The sequences were identical, with the exception of positioning of the poly(A) tail; at least five clones with different polyadenylation sites were found. For a putative full-length cDNA [1775 nucleotides (nt) plus polyadenylation tail], isolated from an embryo cDNA library, an open reading frame of 1419 nt encodes a protein of 473 amino acids (aa) of 51.6 kDa. An alignment of the derived aa sequence with other UGPases has revealed high identity to UGPases from eukaryotic tissues, but not from bacteria. Within the aa sequence, no homology was found to a UDP-glucose-binding motif that has been postulated for a family of glucosyl transferases. The derived aa sequence of UGPase contains three putative N-glycosylation sites and has a highly conserved positioning of five Lys residues, previously shown to be critical for catalysis and substrate binding of potato tuber UGPase. A possible role for N-glycosylation in the intracellular targeting of UGPase is discussed.

  • 206.
    Ekström, Jens-Ola
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Habayeb, Mazen S
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Srivastava, Vaibhav
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Kieselbach, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wingsle, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hultmark, Dan
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Drosophila Nora virus capsid proteins differ from those of other picorna-like viruses2011Inngår i: Virus Research, ISSN 0168-1702, E-ISSN 1872-7492, Vol. 160, nr 1-2, s. 51-58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The recently discovered Nora virus from Drosophila melanogaster is a single-stranded RNA virus. Its published genomic sequence encodes a typical picorna-like cassette of replicative enzymes, but no capsid proteins similar to those in other picorna-like viruses. We have now done additional sequencing at the termini of the viral genome, extending it by 455 nucleotides at the 5' end, but no more coding sequence was found. The completeness of the final 12,333-nucleotide sequence was verified by the production of infectious virus from the cloned genome. To identify the capsid proteins, we purified Nora virus particles and analyzed their proteins by mass spectrometry. Our results show that the capsid is built from three major proteins, VP4A, B and C, encoded in the fourth open reading frame of the viral genome. The viral particles also contain traces of a protein from the third open reading frame, VP3. VP4A and B are not closely related to other picorna-like virus capsid proteins in sequence, but may form similar jelly roll folds. VP4C differs from the others and is predicted to have an essentially α-helical conformation. In a related virus, identified from EST database sequences from Nasonia parasitoid wasps, VP4C is encoded in a separate open reading frame, separated from VP4A and B by a frame-shift. This opens a possibility that VP4C is produced in non-equimolar quantities. Altogether, our results suggest that the Nora virus capsid has a different protein organization compared to the order Picornavirales.

  • 207.
    Eliasson, Mattias
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rännar, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Madsen, Rasmus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Donten, Magdalena A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Marsden-Edwards, Emma
    Waters Corp, Milford, MA 01757 USA .
    Moritz, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Shockcor, John P
    Waters Corp, Milford, MA 01757 USA .
    Johansson, Erik
    Umetr AB, Umeå, Sweden.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Strategy for optimizing LC-MS data processing in Metabolomics: A design of experiments approach2012Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 84, nr 15, s. 6869-6876Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A strategy for optimizing LC-MS metabolomics data processing is proposed. We applied this strategy on the XCMS open source package written in R on both human and plant biology data. The strategy is a sequential design of experiments (DoE) based on a dilution series from a pooled sample and a measure of correlation between diluted concentrations and integrated peak areas. The reliability index metric, used to define peak quality, simultaneously favors reliable peaks and disfavors unreliable peaks using a weighted ratio between peaks with high and low response linearity. DoE optimization resulted in the case studies in more than 57% improvement in the reliability index compared to the use of the default settings. The proposed strategy can be applied to any other data processing software involving parameters to be tuned, e.g., MZmine 2. It can also be fully automated and used as a module in a complete metabolomics data processing pipeline.

  • 208. Endo, Satoshi
    et al.
    Pesquet, Edouard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Tashiro, Gen
    Kuriyama, Hideo
    Goffner, Deborah
    Fukuda, Hiroo
    Demura, Taku
    Transient transformation and RNA silencing in Zinnia tracheary element differentiating cell cultures.2008Inngår i: The Plant journal : for cell and molecular biology, ISSN 1365-313X, Vol. 53, nr 5, s. 864-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Zinnia elegans cell culture system is a robust and physiologically relevant in vitro system for the study of xylem formation. Freshly isolated mesophyll cells of Zinnia can be hormonally induced to semisynchronously transdifferentiate into tracheary elements (TEs). Although the system has proven to be valuable, its utility is diminished by the lack of an efficient transformation protocol. We herein present a novel method to introduce DNA/RNA efficiently into Zinnia cells by electroporation-based transient transformation. Using reporter gene plasmids, we optimized the system for efficiency of transformation and ability for the transformed cells to transdifferentiate into TEs. Optimal conditions included a partial digestion of the cell walls by pectolyase, a low voltage and high capacitance electrical pulse and an optimal medium to maintain cell viability during transformation. Beyond the simple expression of a reporter protein in Zinnia cells, we extended our protocol to subcellular protein targeting, simultaneous co-expression of several reporter proteins and promoter-activity monitoring during TE differentiation. Most importantly, we tested the system for double-stranded RNA (dsRNA)-induced RNA silencing. By introducing in vitro-synthesized dsRNAs, we were able to phenocopy the Arabidopsis cellulose synthase (CesA) mutants that had defects in secondary cell-wall synthesis. Suppressing the expression ofZinnia CesA homologues resulted in an increase of abnormal TEs with aberrant secondary walls. Our electroporation-based transient transformation protocol provides the suite of tools long required for functional analysis and developmental studies at single cell levels.

  • 209.
    Engelken, Johannes
    et al.
    Department of Biology, University of Konstanz, Constance, Germany .
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Adamska, Iwona
    Department of Biology, University of Konstanz, Constance, Germany.
    The extended light-harvesting complex (LHC) protein superfamily: Classification and evolutionary dynamics2012Inngår i: Functinal genomics and evolution of photosynthetic systems / [ed] Robert Burnap, Wim Vermaas, Dordrecht, Netherlands: Springer Netherlands, 2012, s. 265-284Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The evolution of algae and land plants and their photosynthetic machineries is closely connected to the development of the extended light-harvesting complex (LHC) protein superfamily. Therefore, it is not surprising that the molecular organization, function and origin of the LHC proteins have been a central topic in plant biology and photosynthesis research during the last few years. The extended LHC protein superfamily in cyanobacteria and photosynthetic eukaryotes comprises different families, such as the LHC proteins and three groups of light stress-induced proteins, consisting of the LHC-like proteins, the red lineage CAB-like proteins and the photosystem II subunit S. This chapter provides a description of the different extended LHC superfamily members and shows their taxonomic distribution. Furthermore, an overview of scenarios suggested for the evolution of the extended LHC protein superfamily is provided and arised implications for light harvesting, stress responses and photoprotection are discussed.

  • 210. Ensminger, Ingo
    et al.
    Sveshnikov, Dmitry
    Campbell, Douglas A.
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. 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).
    Lloyd, Jon
    Shibistova, Olga
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Intermittent low temperatures constrain spring recovery of photosynthesis in boreal Scots pine forests2004Inngår i: Global Change Biology, ISSN 1354-1013, Vol. 10, nr 6, s. 995-1008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During winter and early spring, evergreen boreal conifers are severely stressed because light energy cannot be used when photosynthesis is pre-empted by low ambient temperatures. To study photosynthetic performance dynamics in a severe boreal climate, seasonal changes in photosynthetic pigments, chloroplast proteins and photochemical efficiency were studied in a Scots pine forest near Zotino, Central Siberia. In winter, downregulation of photosynthesis involved loss of chlorophylls, a twofold increase in xanthophyll cycle pigments and sustained high levels of the light stress-induced zeaxanthin pigment. The highest levels of xanthophylls and zeaxanthin did not occur during the coldest winter period, but rather in April when light was increasing, indicating an increased capacity for thermal dissipation of excitation energy at that time. Concomitantly, in early spring the D1 protein of the photosystem II (PSII) reaction centre and the light-harvesting complex of PSII dropped to their lowest annual levels. In April and May, recovery of PSII activity, chloroplast protein synthesis and rearrangements of pigments were observed as air temperatures increased above 0°C. Nevertheless, severe intermittent low-temperature episodes during this period not only halted but actually reversed the physiological recovery. During these spring low-temperature episodes, protective processes involved a complementary function of the PsbS and early light-induced protein thylakoid proteins. Full recovery of photosynthesis did not occur until the end of May. Our results show that even after winter cold hardening, photosynthetic activity in evergreens responds opportunistically to environmental change throughout the cold season. Therefore, climate change effects potentially improve the sink capacity of boreal forests for atmospheric carbon. However, earlier photosynthesis in spring in response to warmer temperatures is strongly constrained by environmental variation, counteracting the positive effects of an early recovery process.

  • 211. Eriksson, M
    et al.
    Villand, P
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Induction and regulation of expression of a low-CO2-induced mitochondrial carbonic anhydrase in Chlamydomonas reinhardtii1998Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 116, nr 2, s. 637-641Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The time course of and the influence of light intensity and light quality on the induction of a mitochondrial carbonic anhydrase (CA) in the unicellular green alga Chlamydomonas reinhardtii was characterized using western and northern blots. This CA was expressed only under low-CO2 conditions (ambient air). In asynchronously grown cells, the mRNA was detected 15 min after transfer from air containing 5% CO2 to ambient air, and the 21-kD polypeptide was detected on western blots after 1 h. When transferred back to air containing 5% CO2, the mRNA disappeared within 1 h and the polypeptide was degraded within 3 d. Photosynthesis was required for the induction in asynchronous cultures. The induction increased with light up to 500 mu mol m(-2) s(-1), where saturation occurred. In cells grown synchronously, however, expression of the mitochondrial CA was also detected in darkness. Under such conditions the expression followed a circadian rhythm, with mRNA appearing in the dark 30 min before the light was turned on. Algae left in darkness continued this rhythm for several days.

  • 212.
    Eriksson, Maria E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hoffman, Daniel
    Kaduk, Mateusz
    Mauriat, Melanie
    Moritz, Thomas
    Transgenic hybrid aspen trees with increased gibberellin (GA) concentrations suggest that GA acts in parallel with FLOWERING LOCUS T2 to control shoot elongation2015Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 205, nr 3, s. 1288-1295Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bioactive gibberellins (GAs) have been implicated in short day (SD)-induced growth cessation in Populus, because exogenous applications of bioactive GAs to hybrid aspens (Populus tremulaxtremuloides) under SD conditions delay growth cessation. However, this effect diminishes with time, suggesting that plants may cease growth following exposure to SDs due to a reduction in sensitivity to GAs.

    In order to validate and further explore the role of GAs in growth cessation, we perturbed GA biosynthesis or signalling in hybrid aspen plants by overexpressing AtGA20ox1, AtGA2ox2 and PttGID1.3 (encoding GA biosynthesis enzymes and a GA receptor).

    We found trees with elevated concentrations of bioactive GA, due to overexpression of AtGA20ox1, continued to grow in SD conditions and were insensitive to the level of FLOWERING LOCUS T2 (FT2) expression. As transgenic plants overexpressing the PttGID1.3 GA receptor responded in a wild-type (WT) manner to SD conditions, this insensitivity did not result from limited receptor availability.

    As high concentrations of bioactive GA during SD conditions were sufficient to sustain shoot elongation growth in hybrid aspen trees, independent of FT2 expression levels, we conclude elongation growth in trees is regulated by both GA- and long day-responsive pathways, similar to the regulation of flowering in Arabidopsis thaliana.

  • 213.
    Eriksson, Maria E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Webb, Alex A. R.
    Plant cell responses to cold are all about timing2011Inngår i: Current opinion in plant biology, ISSN 1369-5266, E-ISSN 1879-0356, Vol. 14, nr 6, s. 731-737Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Changes in temperature present the cells of plants with particular challenges. Fortunately, many changes in temperature can be anticipated due to the rhythms of day/night and the seasons. To anticipate changes in the environment most organisms have a circadian clock to optimize daily and seasonal timing of gene expression, metabolism, physiology and cell biology. Circadian clocks comprised positive and negative feedback loops which ensure an internal period of approximately 24 hours. We describe the role of the circadian clock in modulating cellular cold signalling networks to prepare the cell for the onset of winter.

  • 214. Eriksson, Mats
    et al.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ISOLATION, PURIFICATION, AND CHARACTERIZATION OF MITOCHONDRIA FROM CHLAMYDOMONAS-REINHARDTII1995Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 107, nr 2, s. 479-483Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mitochondria were isolated from autotrophically grown Chlamydomonas reinhardtii cell-wall-less mutant CW 92. The cells were broken by vortexing with glass beads, and the mitochondria were collected by differential centrifugation and purified on a Percoll gradient. The isolated mitochondria oxidized malate, pyruvate, succinate, NADH, and a-ketoglutarate. Respiratory control was obtained with malate (2.0) and pyruvate (2.2) but not with the other substrates. From experiments with KCN and salicylhydroxamic acid, it was estimated that the capacity of the cytochrome pathway was at least 100 nmol O-2 mg(-1) protein min(-1) and the capacity of the alternative oxidase was at least 50 nmol O-2 mg(-1) protein min(-1). A low sensitivity to oligomycin indicates some difference in the properties of the mitochondrial ATPase from Chlamydomonas as compared to higher plants.

  • 215.
    Eriksson, Mats
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Moseley, Jeffrey L
    Tottey, Stephen
    Del Campo, Jose A
    Quinn, Jeanette
    Kim, Youngbae
    Merchant, Sabeeha
    Genetic dissection of nutritional copper signaling in chlamydomonas distinguishes regulatory and target genes2004Inngår i: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 168, nr 2, s. 795-807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A genetic screen for Chlamydomonas reinhardtii mutants with copper-dependent growth or nonphotosynthetic phenotypes revealed three loci, COPPER RESPONSE REGULATOR 1 (CRR1), COPPER RESPONSE DEFECT 1 (CRD1), and COPPER RESPONSE DEFECT 2 (CRD2), distinguished as regulatory or target genes on the basis of phenotype. CRR1 was shown previously to be required for transcriptional activation of target genes like CYC6, CPX1, and CRD1, encoding, respectively, cytochrome c(6) (which is a heme-containing substitute for copper-containing plastocyanin), coproporphyrinogen III oxidase, and Mg-protoporphyrin IX monomethylester cyclase. We show here that CRR1 is required also for normal accumulation of copper proteins like plastocyanin and ferroxidase in copper-replete medium and for apoplastocyanin degradation in copper-deficient medium, indicating that a single pathway controls nutritional copper homeostasis at multiple levels. CRR1 is linked to the SUPPRESSOR OF PCY1-AC208 13 (SOP13) locus, which corresponds to a gain-of-function mutation resulting in copper-independent expression of CYC6. CRR1 is required also for hypoxic growth, pointing to a physiologically meaningful regulatory connection between copper deficiency and hypoxia. The growth phenotype of crr1 strains results primarily from secondary iron deficiency owing to reduced ferroxidase abundance, suggesting a role for CRR1 in copper distribution to a multicopper ferroxidase involved in iron assimilation. Mutations at the CRD2 locus also result in copper-conditional iron deficiency, which is consistent with a function for CRD2 in a pathway for copper delivery to the ferroxidase. Taken together, the observations argue for a specialized copper-deficiency adaptation for iron uptake in Chlamydomonas.

  • 216.
    Eriksson, Sylvia K
    et al.
    Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Kutzer, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Procek, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Harryson, Pia
    Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Tunable membrane binding of the intrinsically disordered dehydrin Lti30, a cold-induced plant stress protein2011Inngår i: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 23, nr 6, s. 2391-2404Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dehydrins are intrinsically disordered plant proteins whose expression is upregulated under conditions of desiccation and cold stress. Their molecular function in ensuring plant survival is not yet known, but several studies suggest their involvement in membrane stabilization. The dehydrins are characterized by a broad repertoire of conserved and repetitive sequences, out of which the archetypical K-segment has been implicated in membrane binding. To elucidate the molecular mechanism of these K-segments, we examined the interaction between lipid membranes and a dehydrin with a basic functional sequence composition: Lti30, comprising only K-segments. Our results show that Lti30 interacts electrostatically with vesicles of both zwitterionic (phosphatidyl choline) and negatively charged phospholipids (phosphatidyl glycerol, phosphatidyl serine, and phosphatidic acid) with a stronger binding to membranes with high negative surface potential. The membrane interaction lowers the temperature of the main lipid phase transition, consistent with Lti30's proposed role in cold tolerance. Moreover, the membrane binding promotes the assembly of lipid vesicles into large and easily distinguishable aggregates. Using these aggregates as binding markers, we identify three factors that regulate the lipid interaction of Lti30 in vitro: (1) a pH dependent His on/off switch, (2) phosphorylation by protein kinase C, and (3) reversal of membrane binding by proteolytic digest.

  • 217.
    Escamez, Sacha
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Xylem cells cooperate in the control of lignification and cell death during plant vascular development2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The evolutionary success of land plants was fostered by the acquisition of the xylem vascular tissue which conducts water and minerals upwards from the roots. The xylem tissue of flowering plants is composed of three main types of cells: the sap-conducting tracheary elements (TE), the fibres which provide mechanical support and the parenchyma cells which provide metabolic support to the tissue. Both the TEs and the fibres deposit thick polysaccharidic secondary cell walls (SCWs), reinforced by a rigid phenolic polymer called lignin. The cell walls of TEs form efficient water conducting hollow tubes after the TEs have undergone programmed cell death (PCD) and complete protoplast degradation as a part of their differentiation. The work presented in this thesis studied the regulation of TE PCD by characterizing the function of the candidate PCD regulator METACASPASE 9 (MC9) in Arabidopsis thaliana xylogenic cell suspensions. These cell suspensions can be externally induced to differentiate into a mix of TEs and parenchymatic non-TE cells, thus representing an ideal system to study the cellular processes of TE PCD. In this system, TEs with reduced expression of MC9 were shown to have increased levels of autophagy and to trigger the ectopic death of the non-TE cells. The viability of the non-TE cells could be restored by down-regulating autophagy specifically in the TEs with reduced MC9 expression. Therefore, this work showed that MC9 must tightly regulate the level of autophagy during TE PCD in order to prevent the TEs from becoming harmful to the non-TEs. Hence, this work demonstrated the existence of a cellular cooperation between the TEs and the surrounding parenchymatic cells during TE PCD. The potential cooperation between the TEs and the neighbouring parenchyma during the biosynthesis of lignin was also investigated. The cupin domain containing protein PIRIN2 was found to regulate TE lignification in a non-cell autonomous manner in Arabidopsis thaliana. More precisely, PIRIN2 was shown to function as an antagonist of positive transcriptional regulators of lignin biosynthetic genes in xylem parenchyma cells. Part of the transcriptional regulation by PIRIN2 involves chromatin modifications, which represent a new type of regulation of lignin biosynthesis. Because xylem constitutes the wood in tree species, this newly discovered regulation of non-cell autonomous lignification represents a potential target to modify lignin biosynthesis in order to overcome the recalcitrance of the woody biomass for the production of biofuels.

  • 218.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Latha Gandla, Madhavi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Derba-Maceluch, Marta
    Lundqvist, Sven-Olof
    Mellerowicz, Ewa J.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    A collection of genetically engineered Populus trees reveals wood biomass traits that predict glucose yield from enzymatic hydrolysis2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 15798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood represents a promising source of sugars to produce bio-based renewables, including biofuels. However, breaking down lignocellulose requires costly pretreatments because lignocellulose is recalcitrant to enzymatic saccharification. Increasing saccharification potential would greatly contribute to make wood a competitive alternative to petroleum, but this requires improving wood properties. To identify wood biomass traits associated with saccharification, we analyzed a total of 65 traits related to wood chemistry, anatomy and structure, biomass production and saccharification in 40 genetically engineered Populus tree lines. These lines exhibited broad variation in quantitative traits, allowing for multivariate analyses and mathematical modeling. Modeling revealed that seven wood biomass traits associated in a predictive manner with saccharification of glucose after pretreatment. Four of these seven traits were also negatively associated with biomass production, suggesting a trade-off between saccharification potential and total biomass, which has previously been observed to offset the overall sugar yield from whole trees. We therefore estimated the "total-wood glucose yield" (TWG) from whole trees and found 22 biomass traits predictive of TWG after pretreatment. Both saccharification and TWG were associated with low abundant, often overlooked matrix polysaccharides such as arabinose and rhamnose which possibly represent new markers for improved Populus feedstocks.

  • 219.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Contribution of cellular autolysis to tissular functions during plant development2017Inngår i: Current opinion in plant biology, ISSN 1369-5266, E-ISSN 1879-0356, Vol. 35, s. 124-130Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Plant development requires specific cells to be eliminated in a predictable and genetically regulated manner referred to as programmed cell death (PCD). However, the target cells do not merely die but they also undergo autolysis to degrade their cellular corpses. Recent progress in understanding developmental cell elimination suggests that distinct proteins execute PCD sensu stricto and autolysis. In addition, cell death alone and cell dismantlement can fulfill different functions. Hence, it appears biologically meaningful to distinguish between the modules of PCD and autolysis during plant development.

  • 220.
    Fahlén, Jessica
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Landfors, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Freyhult, Eva
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi. Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Bylesjö, Max
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hvidsten, Torgeir
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Rydén, Patrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Bioinformatics strategies for cDNA-microarray data processing2009Inngår i: Batch effects and noise in microarray experiments: sources and solutions / [ed] Scherer, Andreas, Wiley and Sons , 2009, 1, , s. 272s. 61-74Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    

    Pre-processing plays a vital role in cDNA-microarray data analysis. Without proper pre-processing it is likely that the biological conclusions will be misleading. However, there are many alternatives and in order to choose a proper pre-processing procedure it is necessary to understand the effect of different methods. This chapter discusses several pre-processing steps, including image analysis, background correction, normalization, and filtering. Spike-in data are used to illustrate how different procedures affect the analytical ability to detect differentially expressed genes and estimate their regulation. The result shows that pre-processing has a major impact on both the experiment’s sensitivity andits bias. However, general recommendations are hard to give, since pre-processing consists of several actions that are highly dependent on each other. Furthermore, it is likely that pre-processing have a major impact on downstream analysis, such as clustering and classification, and pre-processing methods should be developed and evaluated with this in mind.

  • 221. FALK, S
    et al.
    LEVERENZ, JW
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Oquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    CHANGES IN PHOTOSYSTEM-II FLUORESCENCE IN CHLAMYDOMONAS-REINHARDTII EXPOSED TO INCREASING LEVELS OF IRRADIANCE IN RELATIONSHIP TO THE PHOTOSYNTHETIC RESPONSE TO LIGHT1992Inngår i: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, Vol. 31, nr 1, s. 31-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of a 60 min exposure to photosynthetic photon flux densities ranging from 300 to 2200-mu-mol m-2 s-1 on the photosynthetic light response curve and on PS II heterogeneity as reflected in chlorophyll a fluorescence were investigated using the unicellular green alga Chlamydomonas reinhardtii. It was established that exposure to high light acts at three different regulatory or inhibitory levels; 1) regulation occurs from 300 to 780-mu-mol m-2 s-1 where total amount of PS II centers and the shape of the light response curve is not significantly changed, 2) a first photoinhibitory range above 780 up to 1600-mu-mol m-2 s-1 where a progressive inhibition of the quantum yield and the rate of bending (convexity) of the light response curve can be related to the loss of Q(B)-reducing centers and 3) a second photoinhibitory range above 1600-mu-mol m-2 s-1 where the rate of light saturated photosynthesis also decreases and convexity reaches zero. This was related to a particularly large decrease in PS II(alpha) centers and a large increase in spill-over in energy to PS I.

  • 222. FALK, S
    et al.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    RECOVERY OF PHOTOSYNTHESIS AND PHOTOSYSTEM-II FLUORESCENCE IN CHLAMYDOMONAS-REINHARDTII AFTER EXPOSURE TO 3 LEVELS OF HIGH LIGHT1992Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 85, nr 1, s. 61-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recovery from 60 min of photoinhibitory treatment at photosynthetic photon flux densities of 500, 1400 and 2200-mu-mol m-2 s-1 was followed in cells of the green alga Chlamydomonas reinhardtii grown at 125-mu-mol m-2 s-1. These light treatments re resent photoregulation, moderate photoinhibition and strong photoinhibition, respectively. Treatment in photoregulatory light resulted in an increased maximal rate of oxygen evolution (P(max)) and an increased quantum yield (PHI), but a 15% decrease in F(V)/F(M). Treatment at moderately photoinhibitory light resulted in a 30% decrease in F(V)/F(M) and an approximately equal decrease in PHI. Recovery in dim light restored F(V)/F(M) within 15 and 45 min after high light treatment at 500 and 1 400-mu-mol m-2 s-1 respectively. Convexity (THETA), a measure of the extent of co-limitation between PS II turnover and whole-chain electron transport, and PHI approached, but did not reach the control level during recovery after exposure to 1 400-mu-mol m 2 s-1, whereas P(max) increased above the control. Treatment at 2200-mu-mol m-2 s-1 resulted in a strong reduction of the modeled parameters PHI, THETA and P(max). Subsequent recovery was initially rapid but the rate decreased, and a complete recovery was not reached within 120 min. Based on the results, it is hypothesized that exposure to high light results in two phenomena. The first, expressed at all three light intensities, involves redistribution within the different aspects of PS II heterogeneity rather than a photoinhibitory destruction of PS II reaction centers. The second, most strongly expressed at 2200-mu-mol m-2 s-1, is a physical damage to PS II shown as an almost total loss of PS II(alpha) and PS II Q(B)-reducing centers. Thus recovery displayed two phases, the first was rapid and the only visible phase in algae exposed to 500 and 1 400-mu-mol m-2 s-1. The second phase was slow and visible only in the later part of recovery in cells exposed to 2 200-mu-mol m-2 s-1.

  • 223. FALK, S
    et al.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Oquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    TEMPERATURE-DEPENDENT PHOTOINHIBITION AND RECOVERY OF PHOTOSYNTHESIS IN THE GREEN-ALGA CHLAMYDOMONAS-REINHARDTII ACCLIMATED TO 12 AND 27-DEGREES-C1990Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 78, nr 2, s. 173-180Artikkel i tidsskrift (Fagfellevurdert)
  • 224. Fallath, Thorya
    et al.
    Kidd, Brendan N.
    Stiller, Jiri
    Davoine, Celine
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Björklund, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Manners, John M.
    Kazan, Kemal
    Schenk, Peer M.
    MEDIATOR18 and MEDIATOR20 confer susceptibility to Fusarium oxysporum in Arabidopsis thaliana2017Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 4, artikkel-id e0176022Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The conserved protein complex known as Mediator conveys transcriptional signals by acting as an intermediary between transcription factors and RNA polymerase II. As a result, Mediator subunits play multiple roles in regulating developmental as well as abiotic and biotic stress pathways. In this report we identify the head domain subunits MEDIATOR18 and MEDIATOR20 as important susceptibility factors for Fusarium oxysporum infection in Arabidopsis thaliana. Mutants of MED18 and MED20 display down-regulation of genes associated with jasmonate signaling and biosynthesis while up-regulation of salicylic acid associated pathogenesis related genes and reactive oxygen producing and scavenging genes. We propose that MED18 and MED20 form a sub-domain within Mediator that controls the balance of salicylic acid and jasmonate associated defense pathways.

  • 225. Fei, Xiaowen
    et al.
    Eriksson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Li, Yajun
    Deng, Xiaodong
    A novel negative Fe-deficiency-responsive element and a TGGCA-type-like FeRE control the expression of FTR1 in Chlamydomonas reinhardtii.2010Inngår i: Journal of Biomedicine and Biotechnology, ISSN 1110-7243, E-ISSN 1110-7251, Vol. 2010, s. 790247-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have reported three Fe-deficiency-responsive elements (FEREs), FOX1, ATX1, and FEA1, all of which are positive regulatory elements in response to iron deficiency in Chlamydomonas reinhardtii. Here we describe FTR1, another iron regulated gene and mutational analysis of its promoter. Our results reveal that the FeREs of FTR1 distinguish itself from other iron response elements by containing both negative and positive regulatory regions. In FTR1, the -291/-236 region from the transcriptional start site is necessary and sufficient for Fe-deficiency-inducible expression. This region contains two positive FeREs with a TGGCA-like core sequence: the FtrFeRE1 (ATGCAGGCT) at -287/-279 and the FtrFeRE2 (AAGCGATTGCCAGAGCGC) at -253/-236. Furthermore, we identified a novel FERE, FtrFeRE3 (AGTAACTGTTAAGCC) localized at -319/-292, which negatively influences the expression of FTR1.

  • 226.
    Fei, Xiaowen
    et al.
    Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China.
    Eriksson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Yang, Jinghao
    Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China.
    Deng, Xiaodong
    Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China.
    An Fe deficiency responsive element with a core sequence of TGGCA regulates the expression of FEA1 in Chlamydomonas reinharditii2009Inngår i: Journal of biochemistry, ISSN 1756-2651, Vol. 146, nr 2, s. 157-166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iron is essential to the unicellular green alga Chlamydomonas, but the molecular mechanism for response to iron deficiency remains largely unknown. In previous studies, we have identified FOX1 and ATX1 FEREs (Fe deficiency-responsive elements) as important regulation components of iron response in this organism. Here we present another iron regulated gene FEA1, which promoter was analysed by using a 5'-and 3'-end deletion and a scanning mutagenesis assay. The results reveal that the co-existence of -273/-188 and -118/-49 regions from transcriptional start site of FEA1 were sufficient and necessary for Fe deficiency-induced expression. Further deletion analysis indicates both -273/-253 and -103/-85 regions are essential for inducible expression. The scanning mutagenesis analysis of these regions identifies two cis-acting elements: the FeaFeRE1 at -273/-259 (CTGCGGTGGCAAAGT) and FeaFeRE2 at -106/-85 (CCGCCGCNNNTGGCACCAGCCT). Sequence comparison of FeaFeRE1 and FeaFeRE2 reveals a core sequence of TGGCA, which had been found in our previously reported Fe-deficiency-inducible gene ATX1. Moreover, we show that the promoter region of several genes, including FRE1, IRT1, ISCA, ZRT1, ZRT5, NRAMP2 and COPT1, also contains this core sequence, suggesting that at least two classes FeRE elements exist in Clamydomonas, one in FEA1 and ATX1 and others the second in FOX1, FEA2, MTP4, NRAMP3 and RBOL1.

  • 227. Felten, Judith
    et al.
    Vahala, Jorma
    Love, Jonathan
    Gorzsás, András
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ruggeberg, Markus
    Delhomme, Nicolas
    Lesniewska, Joanna
    Kangasjarvi, Jaakko
    Hvidsten, Torgeir R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences,Ås, Norway.
    Mellerowicz, Ewa J.
    Sundberg, Bjorn
    Ethylene signaling induces gelatinous layers with typical features of tension wood in hybrid aspen2018Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 218, nr 3, s. 999-1014Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The phytohormone ethylene impacts secondary stem growth in plants by stimulating cambial activity, xylem development and fiber over vessel formation. We report the effect of ethylene on secondary cell wall formation and the molecular connection between ethylene signaling and wood formation. We applied exogenous ethylene or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) to wild-type and ethylene-insensitive hybrid aspen trees (Populus tremulaxtremuloides) and studied secondary cell wall anatomy, chemistry and ultrastructure. We furthermore analyzed the transcriptome (RNA Seq) after ACC application to wild-type and ethylene-insensitive trees. We demonstrate that ACC and ethylene induce gelatinous layers (G-layers) and alter the fiber cell wall cellulose microfibril angle. G-layers are tertiary wall layers rich in cellulose, typically found in tension wood of aspen trees. A vast majority of transcripts affected by ACC are downstream of ethylene perception and include a large number of transcription factors (TFs). Motif-analyses reveal potential connections between ethylene TFs (Ethylene Response Factors (ERFs), ETHYLENE INSENSITIVE 3/ETHYLENE INSENSITIVE3-LIKE1 (EIN3/EIL1)) and wood formation. G-layer formation upon ethylene application suggests that the increase in ethylene biosynthesis observed during tension wood formation is important for its formation. Ethylene-regulated TFs of the ERF and EIN3/EIL1 type could transmit the ethylene signal.

  • 228. Fernie, A. R.
    et al.
    Bauwe, H.
    Eisenhut, M.
    Florian, A.
    Hanson, D. T.
    Hagemann, M.
    Keech, Olivier
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Mielewczik, M.
    Nikoloski, Z.
    Peterhaensel, C.
    Roje, S.
    Sage, R.
    Timm, S.
    von Cammerer, S.
    Weber, A. P. M.
    Westhoff, P.
    Perspectives on plant photorespiratory metabolism2013Inngår i: Plant Biology, ISSN 1435-8603, E-ISSN 1438-8677, Vol. 15, nr 4, s. 748-753Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Being intimately intertwined with (C3) photosynthesis, photorespiration is an incredibly high flux-bearing pathway. Traditionally, the photorespiratory cycle was viewed as closed pathway to refill the Calvin-Benson cycle with organic carbon. However, given the network nature of metabolism, it hence follows that photorespiration will interact with many other pathways. In this article, we review current understanding of these interactions and attempt to define key priorities for future research, which will allow us greater fundamental comprehension of general metabolic and developmental consequences of perturbation of this crucial metabolic process.

  • 229. Ferrando, Alejandro
    et al.
    Mar Castellano, M.
    Lison, Purificacion
    Leister, Dario
    Stepanova, Anna N.
    Hanson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Editorial: Relevance of Translational Regulation on Plant Growth and Environmental Responses2017Inngår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 8, artikkel-id 2170Artikkel i tidsskrift (Annet vitenskapelig)
  • 230. Ferreira, Sílvia
    et al.
    Hjernø, Karin
    Larsen, Martin
    Wingsle, Gunnar
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Umeå Plant Science Centre.
    Larsen, Peter
    Fey, Stephen
    Roepstorff, Peter
    Salomé Pais, Maria
    Proteome profiling of Populus euphratica Oliv. upon heat stress.2006Inngår i: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 98, nr 2, s. 361-77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND AND AIMS: Populus euphratica is a light-demanding species ecologically characterized as a pioneer. It grows in shelter belts along riversides, being part of the natural desert forest ecosystems in China and Middle Eastern countries. It is able to survive extreme temperatures, drought and salt stress, marking itself out as an important plant species to study the mechanisms responsible for survival of woody plants under heat stress. METHODS: Heat effects were evaluated through electrolyte leakage on leaf discs, and LT(50) was determined to occur above 50 degrees C. Protein accumulation profiles of leaves from young plants submitted to 42/37 degrees C for 3 d in a phytotron were determined through 2D-PAGE, and a total of 45 % of up- and downregulated proteins were detected. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)/TOF analysis, combined with searches in different databases, enabled the identification of 82 % of the selected spots. KEY RESULTS: Short-term upregulated proteins are related to membrane destabilization and cytoskeleton restructuring, sulfur assimilation, thiamine and hydrophobic amino acid biosynthesis, and protein stability. Long-term upregulated proteins are involved in redox homeostasis and photosynthesis. Late downregulated proteins are involved mainly in carbon metabolism. CONCLUSIONS: Moderate heat response involves proteins related to lipid biogenesis, cytoskeleton structure, sulfate assimilation, thiamine and hydrophobic amino acid biosynthesis, and nuclear transport. Photostasis is achieved through carbon metabolism adjustment, a decrease of photosystem II (PSII) abundance and an increase of PSI contribution to photosynthetic linear electron flow. Thioredoxin h may have a special role in this process in P. euphratica upon moderate heat exposure.

  • 231.
    Forsberg, Göte
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Pediatrik.
    Fahlgren, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Immunologi/immunkemi.
    Hörstedt, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hammarström, Sten
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Immunologi/immunkemi.
    Hernell, Olle
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Pediatrik.
    Hammarström, Marie-Louise
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Immunologi/immunkemi.
    Presence of bacteria and innate immunity of intestinal epithelium in childhood celiac disease2004Inngår i: American Journal of Gastroenterology, ISSN 0002-9270, E-ISSN 1572-0241, Vol. 99, nr 5, s. 894-904Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVES: Exposure to gliadin and related prolamins and appropriate HLA-DQ haplotype are necessary but not sufficient for contracting celiac disease (CD). Aberrant innate immune reactions could be contributing risk factors. Therefore, jejunal biopsies were screened for bacteria and the innate immune status of the epithelium investigated.

    METHODS: Children with untreated, treated, challenged CD, and controls were analyzed. Bacteria were identified by scanning electron microscopy. Glycocalyx composition and mucin and antimicrobial peptide production were studied by quantitative RT-PCR, antibody and lectin immunohistochemistry.

    RESULTS: Rod-shaped bacteria were frequently associated with the mucosa of CD patients, with both active and inactive disease, but not with controls. The lectin Ulex europaeus agglutinin I (UEAI) stained goblet cells in the mucosa of all CD patients but not of controls. The lectin peanut agglutinin (PNA) stained glycocalyx of controls but not of CD patients. mRNA levels of mucin-2 (MUC2), alpha-defensins HD-5 and HD-6, and lysozyme were significantly increased in active CD and returned to normal in treated CD. Their expression levels correlated to the interferon-gamma mRNA levels in intraepithelial lymphocytes. MUC2, HD-5, and lysozyme proteins were seen in absorptive epithelial cells. beta-defensins hBD-1 and hBD-2, carcinoembryonic antigen (CEA), CEA cell adhesion molecule-1a (CEACAM1a), and MUC3 were not affected.

    CONCLUSIONS: Unique carbohydrate structures of the glycocalyx/mucous layer are likely discriminating features of CD patients. These glycosylation differences could facilitate bacterial adhesion. Ectopic production of MUC2, HD-5, and lysozyme in active CD is compatible with goblet and Paneth cell metaplasia induced by high interferon-gamma production by intraepithelial lymphocytes.

  • 232. Forsum, Oskar
    et al.
    Näsholm, Torgny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Transformation of Plants with D-Amino Acid Resistance Selectable Markers2009Inngår i: D-Amino Acids: Practical Methods and Protocols, Volume 4: Enzymes Involved in the Metabolism of D-Amino Acids / [ed] Ryuichi Konno, Hans Brückner, Antimo D'Aniello, George H. Fisher, Noriko Fujii and Hiroshi Homma, Hauppauge: Nova Science Publishers, Inc., 2009, s. 73-79Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 233. Fournier, Auriel M. V.
    et al.
    Sullivan, Alexis R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bump, Joseph K.
    Perkins, Marie
    Shieldcastle, Mark C.
    King, Sammy L.
    Combining citizen science species distribution models and stable isotopes reveals migratory connectivity in the secretive Virginia rail2017Inngår i: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 54, nr 2, s. 618-627Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Stable hydrogen isotope (delta D) methods for tracking animal movement are widely used yet often produce low resolution assignments. Incorporating prior knowledge of abundance, distribution or movement patterns can ameliorate this limitation, but data are lacking for most species. We demonstrate how observations reported by citizen scientists can be used to develop robust estimates of species distributions and to constrain dD assignments. 2. We developed a Bayesian framework to refine isotopic estimates of migrant animal origins conditional on species distribution models constructed from citizen scientist observations. To illustrate this approach, we analysed the migratory connectivity of the Virginia rail Rallus limicola, a secretive and declining migratory game bird in North America. 3. Citizen science observations enabled both estimation of sampling bias and construction of bias-corrected species distribution models. Conditioning dD assignments on these species distribution models yielded comparably high-resolution assignments. 4. Most Virginia rails wintering across five Gulf Coast sites spent the previous summer near the Great Lakes, although a considerable minority originated from the Chesapeake Bay watershed or Prairie Pothole region of North Dakota. Conversely, the majority of migrating Virginia rails from a site in the Great Lakes most likely spent the previous winter on the Gulf Coast between Texas and Louisiana. 5. Synthesis and applications. In this analysis, Virginia rail migratory connectivity does not fully correspond to the administrative flyways used to manage migratory birds. This example demonstrates that with the increasing availability of citizen science data to create species distribution models, our framework can produce high-resolution estimates of migratory connectivity for many animals, including cryptic species. Empirical evidence of links between seasonal habitats will help enable effective habitat management, hunting quotas and population monitoring and also highlight critical knowledge gaps.

  • 234. Fracheboud, Yvan
    et al.
    Luquez, Virginia
    Björkén, Lars
    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, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Tuominen, Hannele
    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).
    The control of autumn senescence in European aspen2009Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 149, nr 4, s. 1982-1991Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The initiation, progression, and natural variation of autumn senescence in European aspen (Populus tremula) was investigated by monitoring chlorophyll degradation in (1) trees growing in natural stands and (2) cloned trees growing in a greenhouse under various light regimes. The main trigger for the initiation of autumn senescence in aspen is the shortening photoperiod, but there was a large degree of variation in the onset of senescence, both within local populations and among trees originating from different populations, where it correlated with the latitude of their respective origins. The variation for onset of senescence with a population was much larger than the variation of bud set. Once started, autumn senescence was accelerated by low temperature and longer nights, and clones that started to senescence late had a faster senescence. Bud set and autumn senescence appeared to be under the control of two independent critical photoperiods, but senescence could not be initiated until a certain time after bud set, suggesting that bud set and growth arrest are important for the trees to acquire competence to respond to the photoperiodic trigger to undergo autumn senescence. A timetable of events related to bud set and autumn senescence is presented.

  • 235.
    Frenkel, Martin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bellafiore, Stephane
    Rochaix, Jean-David
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hierarchy amongst photosynthetic acclimation responses for plant fitness2007Inngår i: Physiologia Plantarum, Vol. 129, nr 2, s. 455-459Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have compared the seed production of Arabidopsis wild-type and mutant plants impaired in the regulation of the photosynthetic light reactions grown under natural conditions in the field. Mutant plants (npq4) lacking feedback de-excitation were, as previously demonstrated, severely affected in seed production. Seed sets of plants deficient in state transitions (stn7) were 19% smaller than those of wild-type plants, whereas plants missing the STN8 kinase required for the phosphorylation of the core photosystem II reaction centre polypeptides (stn8) had a normal seed production. Plants lacking both STN7 and STN8 kinases were strongly affected, indicating that these mutations act synergistically. In contrast, npq4×stn7 double mutants had the same seed set as npq4 mutants.

  • 236.
    Frenkel, Martin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Johansson Jänkänpää, Hanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Plant photoprotection influences herbivore preferencesManuskript (Annet (populærvitenskap, debatt, mm))
  • 237.
    Frenkel, Martin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Johansson Jänkänpää, Hanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    An illustrated gardener's guide to transgenic Arabidopsis field experiments2008Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 180, nr 2, s. 545-555Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Field studies with transgenic Arabidopsislines have been performed over 8 yr, to better understand the influence that certain genes have on plant performance. Many (if not most) plant phenotypes cannot be observed under the near constant, low-stress conditions in growth chambers, making field experiments necessary. However, there are challenges in performing such experiments: permission must be obtained and regulations obeyed, the profound influence of uncontrollable biotic and abiotic factors has to be considered, and experimental design has to be strictly controlled.

    The aim here is to provide inspiration and guidelines for researchers who are not used to setting up such experiments, allowing others to learn from our mistakes. This is believed to be the first example of a ‘manual’ for field experiments with transgenic Arabidopsisplants. Many of the challenges encountered are common for all field experiments, and many researchers from ecological backgrounds are skilled in such methods. There is huge potential in combining the detailed mechanistic understanding of molecular biologists with ecologists’ expertise in examining plant performance under field conditions, and it is suggested that more interdisciplinary collaborations will open up new scientific avenues to aid analyses of the roles of genetic and physiological variation in natural systems.

  • 238.
    Frenkel, Martin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Külheim, Carsten
    Johansson Jänkänpää, Hanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Skogström, Oskar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Dall Osto, Luca
    Ågren, Jon
    Bassi, Roberto
    Moritz, Thomas
    Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences.
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Improper excess light energy dissipation in Arabidopsis results in a metabolic reprogramming2009Inngår i: BMC Plant Biology, ISSN 1471-2229, E-ISSN 1471-2229, Vol. 9, nr 12, s. 1-16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Plant performance is affected by the level of expression of PsbS, a key photoprotective protein involved in the process of feedback de-excitation (FDE), or the qE component of non-photochemical quenching, NPQ.

    Results: In studies presented here, under constant laboratory conditions the metabolite profiles of leaves of wild-type Arabidopsis thaliana and plants lacking or overexpressing PsbS were very similar, but under natural conditions their differences in levels of PsbS expression were associated with major changes in metabolite profiles. Some carbohydrates and amino acids differed ten-fold in abundance between PsbS-lacking mutants and over-expressers, with wild-type plants having intermediate amounts, showing that a metabolic shift had occurred. The transcriptomes of the genotypes also varied under field conditions, and the genes induced in plants lacking PsbS were similar to those reportedly induced in plants exposed to ozone stress or treated with methyl jasmonate (MeJA). Genes involved in the biosynthesis of JA were up-regulated, and enzymes involved in this pathway accumulated. JA levels in the undamaged leaves of field-grown plants did not differ between wild-type and PsbS-lacking mutants, but they were higher in the mutants when they were exposed to herbivory.

    Conclusion: These findings suggest that lack of FDE results in increased photooxidative stress in the chloroplasts of Arabidopsis plants grown in the field, which elicits a response at the transcriptome level, causing a redirection of metabolism from growth towards defence that resembles a MeJA/JA response.

  • 239.
    Frenkel, Martin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Külheim, Carsten
    Johansson Jänkänpää, Hanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Skogström, Oskar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Frigerio, Sara
    Ågren, Jon
    Bassi, Roberto
    Moritz, Thomas
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Improper regulation of light harvesting in Arabidopsis results in a metabolic reprogrammingManuskript (Annet (populærvitenskap, debatt, mm))
  • 240.
    Frescatada-Rosa, Marcia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Stanislas, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Backues, Steven K.
    Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
    Reichardt, Ilka
    Department of Developmental Genetics, Centre for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
    Men, Shuzhen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Boutte, Yohann
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Jürgens, Gerd
    Department of Developmental Genetics, Centre for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
    Moritz, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Bednarek, Sebastian Y.
    Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Institute for Biochemistry and Biology, Plant Physiology, University of Potsdam, Potsdam-Golm, Germany.
    High lipid order of Arabidopsis cell-plate membranes mediated by sterol and DYNAMIN-RELATED PROTEIN1A function2014Inngår i: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 80, nr 5, s. 745-757Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Membranes of eukaryotic cells contain high lipid-order sterol-rich domains that are thought to mediate temporal and spatial organization of cellular processes. Sterols are crucial for execution of cytokinesis, the last stage of cell division, in diverse eukaryotes. The cell plate of higher-plant cells is the membrane structure that separates daughter cells during somatic cytokinesis. Cell-plate formation in Arabidopsis relies on sterol- and DYNAMIN-RELATED PROTEIN1A (DRP1A)-dependent endocytosis. However, functional relationships between lipid membrane order or lipid packing and endocytic machinery components during eukaryotic cytokinesis have not been elucidated. Using ratiometric live imaging of lipid order-sensitive fluorescent probes, we show that the cell plate of Arabidopsis thaliana represents a dynamic, high lipid-order membrane domain. The cell-plate lipid order was found to be sensitive to pharmacological and genetic alterations of sterol composition. Sterols co-localize with DRP1A at the cell plate, and DRP1A accumulates in detergent-resistant membrane fractions. Modifications of sterol concentration or composition reduce cell-plate membrane order and affect DRP1A localization. Strikingly, DRP1A function itself is essential for high lipid order at the cell plate. Our findings provide evidence that the cell plate represents a high lipid-order domain, and pave the way to explore potential feedback between lipid order and function of dynamin-related proteins during cytokinesis.

  • 241.
    Frescatada-Rosa, Márcia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Dissecting sterol function during clathrin-dependent endocytosis and cytokinesis in Arabidopsis thaliana2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Sterols are lipid components of eukaryotic membranes. Alterations of membrane sterol composition perturb the execution of cell division, which in diverse eukaryotes can have severe consequences for development of the organism. Partitioning of the cytoplasm during cell division occurs at the final stage of cell division named cytokinesis. In somatic plant cells, cytokinesis is initiated by fusion of membrane vesicles in the plane of cell division resulting in a transient compartment termed the cell plate. Cell plate maturation relies on temporal and spatial orchestration of membrane fusion and endocytosis. Impaired vesicle fusion or defects in endocytosis result in cytokinetic defects.

    In Arabidopsis thaliana, the KNOLLE and DYNAMIN-RELATED PROTEIN 1A (DRP1A) contribute to cytokinesis. KNOLLE mediates fusion of vesicles at the plane of cell division while DRP1A appears to be involved in cell plate maturation through its role in clathrin-mediated endocytosis.

    This thesis shows that KNOLLE is specifically restricted to the cell division plane through sterol-dependent endocytosis that involves a clathrin- and DRP1A-mediated mechanism. Sterols affect internalization of KNOLLE through their role in lateral membrane organization by keeping diffusion of KNOLLE to lateral membranes in check via its endocytic removal. It is shown that the cell plate represents a high-lipid-order membrane domain that depends on the correct composition and the right concentration of sterols. Accumulation of DRP1A at the cell plate requires correct sterol concentration and composition similar to high-lipid order. Conversely, high-lipid-order at the cell plate relies on DRP1A activity suggesting a feedback between DRP1A function and lipid order establishment. Finally, it is shown that sterols are also present at the tonoplast of dividing and elongated root cells.

    Taken together, the results reveal that formation of the cell plate in Arabidopsis thaliana depends on an intricate interplay between cytokinetic vesicle fusion, sterol-dependent lateral membrane and high-lipid-order domain organization as well as endocytic machinery function.

  • 242.
    Freyhult, Eva
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Landfors, Mattias
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Önskog, Jenny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hvidsten, Torgeir R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Rydén, Patrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Umeå universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Challenges in microarray class discovery: a comprehensive examination of normalization, gene selection and clustering2010Inngår i: BMC Bioinformatics, ISSN 1471-2105, E-ISSN 1471-2105, Vol. 11, artikkel-id 503Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Cluster analysis, and in particular hierarchical clustering, is widely used to extract information from gene expression data. The aim is to discover new classes, or sub-classes, of either individuals or genes. Performing a cluster analysis commonly involve decisions on how to; handle missing values, standardize the data and select genes. In addition, pre processing, involving various types of filtration and normalization procedures, can have an effect on the ability to discover biologically relevant classes. Here we consider cluster analysis in a broad sense and perform a comprehensive evaluation that covers several aspects of cluster analyses, including normalization.

    Result: We evaluated 2780 cluster analysis methods on seven publicly available 2-channel microarray data sets with common reference designs. Each cluster analysis method differed in data normalization (5 normalizations were considered), missing value imputation (2), standardization of data (2), gene selection (19) or clustering method (11). The cluster analyses are evaluated using known classes, such as cancer types, and the adjusted Rand index. The performances of the different analyses vary between the data sets and it is difficult to give general recommendations. However, normalization, gene selection and clustering method are all variables that have a significant impact on the performance. In particular, gene selection is important and it is generally necessary to include a relatively large number of genes in order to get good performance. Selecting genes with high standard deviation or using principal component analysis are shown to be the preferred gene selection methods. Hierarchical clustering using Ward's method, k-means clustering and Mclust are the clustering methods considered in this paper that achieves the highest adjusted Rand. Normalization can have a significant positive impact on the ability to cluster individuals, and there are indications that background correction is preferable, in particular if the gene selection is successful. However, this is an area that needs to be studied further in order to draw any general conclusions.

    Conclusions: The choice of cluster analysis, and in particular gene selection, has a large impact on the ability to cluster individuals correctly based on expression profiles. Normalization has a positive effect, but the relative performance of different normalizations is an area that needs more research. In summary, although clustering, gene selection and normalization are considered standard methods in bioinformatics, our comprehensive analysis shows that selecting the right methods, and the right combinations of methods, is far from trivial and that much is still unexplored in what is considered to be the most basic analysis of genomic data.

  • 243. Fritz, Richard
    et al.
    Hochwender, Carl
    Albrectsen, Benedicte
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Czorsak, Martin
    Fitness and genetic architecture of parent and hybrid willows in common gardens2006Inngår i: Evolution, Vol. 60, s. 1215-1227Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of inorganic phosphate (Pi) status, light/dark and sucrose on expression of UDP-glucose pyrophosphorylase (UGPase) gene (Ugp), which is involved in sucrose/ polysaccharides metabolism, were investigated using Arabidopsis wild-type (wt) plants and mutants impaired in Pi and carbohydrate status. Generally, P-deficiency resulted in increased Ugp expression and enhanced UGPase activity and protein content, as found for wt plants grown on P-deficient and complete nutrient solution, as well as for pho1 (P-deficient) mutants. Ugp was highly expressed in darkened leaves of pho1, but not wt plants, daily tight exposure enhanced Ugp expression both in wt and pho mutants. The pho1 and pho2 (Pi-accumulating) mutations had Little or no effect on leaf contents of glucose and fructose, regardless of light/dark conditions, whereas pho1 plants had much higher Levels of sucrose and starch in the dark than pho2 and wt plants. The Ugp was up-regutated when leaves were fed with sucrose in wt plants, but the expression in pho2 background was much less sensitive to sucrose supply than in wt and pho1 plants. Expression of Ugp in pgm1 and sex1 mutants (impaired in starch/sugar content) was not dependent on starch content, and not tightly correlated with soluble sugar status. Okadaic acid (OKA) effectively blocked the P-starvation and sucrose -dependent expression of Ugp in excised leaves, whereas staurosporine (STA) had only a small effect on both processes (especially in -P leaves), suggesting that P-starvation and sucrose effects on Ugp are transmitted by pathways that may share similar components with respect to their (in)sensitivity to OKA and STA. The results of this study suggest that Ugp expression is modulated by an interaction of signals derived from P-deficiency status, sucrose content and dark/ light conditions, and that light/ sucrose and P-deficiency may have additive effects on Ugp expression. (c) 2004 Elsevier GmbH. All rights reserved.

  • 244.
    Funda, Tomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Department of Forest Genetics and Plant Physiology, UPSCSwedish University of Agricultural Sciences, Umeå, Sweden.
    Wennström, Ulfstand
    Almqvist, Curt
    Andersson Gull, Bengt
    Wang, Xiao-Ru
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Mating dynamics of Scots pine in isolation tents2016Inngår i: Tree Genetics & Genomes, ISSN 1614-2942, E-ISSN 1614-2950, Vol. 12, nr 6, artikkel-id 112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seed orchards are forest tree production populations for supplying the forest industry with consistent and abundant seed crops of superior genetic quality. However, genetic quality can be severely affected by non-random mating among parents and the occurrence of background pollination. This study analyzed mating structure and background pollination in six large isolation tents established in a clonal Scots pine seed orchard in northern Sweden. The isolation tents were intended to form a physical barrier against background pollen and induce earlier flowering relative to the surrounding trees. We scored flowering phenology inside and outside the tents and tracked airborne pollen density inside and outside the seed orchard in three consecutive pollination seasons. We genotyped 5683 offspring collected from the tents and open controls using nine microsatellite loci, and assigned paternity using simple exclusion method. We found that tent trees shed pollen and exhibited maximum female receptivity approximately 1 week earlier than trees in open control. The majority of matings in tents (78.3 %) occurred at distances within two trees apart (about 5 m). Self-fertilization was relatively high (average 21.8 %) in tents without supplemental pollination (SP), but it was substantially reduced in tents with SP (average 7.7 %). Pollen contamination was low in open controls (4.8-7.1 %), and all tents remained entirely free of foreign pollen. Our study demonstrates that tent isolation is effective in blocking pollen immigration and in manipulating flowering phenology. When complimented with supplemental pollination, it could become a useful seed orchard management practice to optimize the gain and diversity of seed orchard crops.

  • 245. Fülöp, Katalin
    et al.
    Pettkó-Szandtner, Aladàr
    Magyar, Zoltán
    Miskolczi, Pál
    Kondorosi, Eva
    Dudits, Dénes
    Bako, Laszlo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    The Medicago CDKC;1-CYCLINT;1 kinase complex phosphorylates the carboxy-terminal domain of RNA polymerase II and promotes transcription.2005Inngår i: Plant Journal, ISSN 0960-7412, Vol. 42, nr 6, s. 810-20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Ms;CDKC;1 kinase is structurally similar to those cyclin-dependent kinases (CDKs) that are not involved directly in cell cycle regulation. The presence of a PITAIRE motif in Ms;CDKC;1 suggests that it interacts with cyclins different from known PSTAIRE/PPTALRE kinase regulatory subunits. Here we demonstrate that a Medicago CYCLINT (CYCT) protein is a specific interactor of Ms;CDKC;1 and the interaction between these two proteins gives rise to an active kinase complex that localizes to the nucleus and phosphorylates the carboxy-terminal YSPTSPS heptapeptide repeat domain (CTD) of the largest subunit of RNA polymerase II in vitro. Mutation of Ser to Ala at position 5 within the heptapeptide repeat abolishes substrate phosphorylation by the Ms;CDKC;1 kinase complex. Furthermore, our data show that addition of the Medicago CDKC;1-CYCT;1 heterodimer completely restored the transcriptional activity of a HeLa nuclear extract depleted of endogeneous CDK9 kinase complexes. Together, these results indicate that the Medicago CDKC;1-CYCT;1 complex is a positive regulator of transcription in plants and has a role similar to the CDK9/cyclin T complex of human positive transcription elongation factor P-TEFb.

  • 246. Fülöp, Katalin
    et al.
    Tarayre, Sylvie
    Kelemen, Zsolt
    Horváth, Gábor
    Kevei, Zoltán
    Nikovics, Krisztina
    Bakó, László
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Biological Research Center; Hungarian Academy of Sciences; Szeged, Hungary.
    Brown, Spencer
    Kondorosi, Adam
    Kondorosi, Eva
    Arabidopsis anaphase-promoting complexes: multiple activators and wide range of substrates might keep APC perpetually busy2005Inngår i: Cell Cycle, ISSN 1538-4101, E-ISSN 1551-4005, Vol. 4, nr 8, s. 1084-1092Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The anaphase-promoting complex (APC), a multisubunit E3 ubiquitin ligase, is an essential regulator of the cell cycle from metaphase until S phase in yeast and metazoans. APC mediates degradation of numerous cell cycle-related proteins, including mitotic cyclins and its activation and substrate-specificity are determined by two adaptor proteins, Cdc20 and Cdh1. Plants have multiple APC activators and the Cdh1-type proteins, in addition, are represented by two subclasses, known as Ccs52A and Ccs52B. The Arabidopsis genome contains five cdc20 genes as well as ccs52A1, ccs52A2 and ccs52B.In Schizosaccharomyces pombe, expression of the three Atccs52 genes elicited distinct phenotypes supporting nonredundant function of the AtCcs52 proteins. Consistent with these activities, the AtCcs52 proteins were able to bind both to the yeast and the Arabidopsis APCs. In synchronized Arabidopsis cell cultures the cdc20 transcripts were present from early G2 until the M-phase exit, ccs52B from G2/M to M while ccs52A1 and ccs52A2 were from late M until early G2, suggesting consecutive action of these APC activators in the plant cell cycle. The AtCcs52 proteins interacted with different subsets of mitotic cyclins, in accordance with their expression profiles, either in free- or CDK-bound forms. Expression of most APC subunits was constitutive, whereas cdc27a and cdc27b, corresponding to two forms of apc3, and ubc19 and ubc20 encoding E2-C type ubiquitin-conjugating enzymes displayed differences in their cell cycle regulation. These data indicate the existence of numerous APC(Cdc20/Ccs52/Cdc27) forms in Arabidopsis, which in conjunction with different E2 enzymes might have distinct or complementary functions at distinct stages of the cell cycle.

  • 247. Galvao, Vinicius Costa
    et al.
    Collani, Silvio
    Horrer, Daniel
    Schmid, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Gibberellic acid signaling is required for ambient temperature-mediated induction of flowering in Arabidopsis thaliana2015Inngår i: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 84, nr 5, s. 949-962Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Distinct molecular mechanisms integrate changes in ambient temperature into the genetic pathways that govern flowering time in Arabidopsis thaliana. Temperature-dependent eviction of the histone variant H2A.Z from nucleosomes has been suggested to facilitate the expression of FT by PIF4 at elevated ambient temperatures. Here we show that, in addition to PIF4, PIF3 and PIF5, but not PIF1 and PIF6, can promote flowering when expressed specifically in phloem companion cells (PCC), where they can induce FT and its close paralog, TSF. However, despite their strong potential to promote flowering, genetic analyses suggest that the PIF genes seem to have only a minor role in adjusting flowering in response to photoperiod or high ambient temperature. In addition, loss of PIF function only partially suppressed the early flowering phenotype and FT expression of the arp6 mutant, which is defective in H2A.Z deposition. In contrast, the chemical inhibition of gibberellic acid (GA) biosynthesis resulted in a strong attenuation of early flowering and FT expression in arp6. Furthermore, GA was able to induce flowering at low temperature (15 degrees C) independently of FT, TSF, and the PIF genes, probably directly at the shoot apical meristem. Together, our results suggest that the timing of the floral transition in response to ambient temperature is more complex than previously thought and that GA signaling might play a crucial role in this process.

  • 248. Gama, Filipe
    et al.
    Keech, Olivier
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Eymery, Francoise
    Finkemeier, Iris
    Gelhaye, Eric
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Dietz, Karl Josef
    Rey, Pascal
    Jacquot, Jean-Pierre
    Rouhier, Nicolas
    The mitochondrial type II peroxiredoxin from poplar2007Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 129, nr 1, s. 196-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mitochondria are a major site of reactive oxygen species production and controlling the peroxide levels in this compartment is essential. Peroxiredoxins (Prx) are heme-free peroxidases, which use reactive cysteines for their catalysis and reducing systems for their regeneration. One of the two Prxs present in poplar mitochondria, Prx IIF, expressed as a recombinant protein, was found to reduce a broad range of peroxides with electrons provided preferentially by glutaredoxin and to a lesser extent by glutathione, all the thioredoxins tested being inefficient. This protein is constitutively expressed because it is found in all tissues analyzed. Its expression is modified during a biotic interaction between poplar and the rust fungus Melampsora laricii populina. On the other hand, Prx IIF expression does not substantially vary under abiotic stress conditions. Nevertheless, water deficit or chilling and probably induced senescence, but not photooxidative conditions or heavy metal treatment, also led to a small increase in PrxIIF abundance in Arabidopsis thaliana plants.

  • 249. Gamm, Magdalena
    et al.
    Peviani, Alessia
    Honsel, Anne
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Snel, Berend
    Smeekens, Sjef
    Hanson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Increased sucrose levels mediate selective mRNA translation in Arabidopsis2014Inngår i: BMC Plant Biology, ISSN 1471-2229, E-ISSN 1471-2229, Vol. 14, artikkel-id 306Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Protein synthesis is a highly energy demanding process and is regulated according to cellular energy levels. Light and sugar availability affect mRNA translation in plant cells but the specific roles of these factors remain unclear. In this study, sucrose was applied to Arabidopsis seedlings kept in the light or in the dark, in order to distinguish sucrose and light effects on transcription and translation. These were studied using microarray analysis of steady-state mRNA and mRNA bound to translating ribosomes. Results: Steady-state mRNA levels were affected differently by sucrose in the light and in the dark but general translation increased to a similar extent in both conditions. For a majority of the transcripts changes of the transcript levels were followed by changes in polysomal mRNA levels. However, for 243 mRNAs, a change in polysomal occupancy (defined as polysomal levels related to steady-state levels of the mRNA) was observed after sucrose treatment in the light, but not in the dark condition. Many of these mRNAs are annotated as encoding ribosomal proteins, supporting specific translational regulation of this group of transcripts. Unexpectedly, the numbers of ribosomes bound to each mRNA decreased for mRNAs with increased polysomal occupancy. Conclusions: Our results suggest that sucrose regulate translation of these 243 mRNAs specifically in the light, through a novel regulatory mechanism. Our data shows that increased polysomal occupancy is not necessarily leading to more ribosomes per transcript, suggesting a mechanism of translational induction not solely dependent on increased translation initiation rates.

  • 250.
    Ganeteg, U.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Strand, Åsa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Gustafsson, P.
    Jansson, S.
    The properties of the chlorophyll a/b-binding proteins Lhca2 and Lhca3 studied in vivo using antisense inhibition2001Inngår i: Plant Physiol, Vol. 127, s. 150-158Artikkel i tidsskrift (Fagfellevurdert)
2345678 201 - 250 of 1013
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