umu.sePublikasjoner
Endre søk
Begrens søket
3456789 251 - 300 of 1158
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 251.
    Eriksson, Birgitta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Studies on Ascomycetes and Deuteromycetes on Diapensiales and Ericales in Fennoscandia1974Doktoravhandling, med artikler (Annet vitenskapelig)
  • 252. 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.

  • 253.
    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.

  • 254.
    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.

  • 255. 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.

  • 256.
    Eriksson, Mats
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Ramazanov, Zakir
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Discovery of an algal mitochondrial carbonic anhydrase: molecular cloning and characterization of a low-CO2-induced polypeptide in Chlamydomonas reinhardtii1996Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 93, nr 21, s. 12031-12034Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In green unicellular algae, several polypeptides are induced upon exposure to limiting CO2. We report here on the localization and characterization of one of these, a 22-kDa polypeptide in Chlamydomonas reinhardtii. This nuclear-encoded polypeptide is induced in the mitochondria by a lowering of the partial pressure of CO2 in the growth medium from 5% to air CO2 levels. Sequencing of two different cDNA clones coding for the polypeptide identified it as a 20.7-kDa beta-type carbonic anhydrase (CA; carbonate dehydratase, carbonate hydro-lyase, EC 4.2.1.1). The two clones differ in their nucleotide sequences but code for identical proteins, showing that this CA is encoded by at least two genes. Northern blot hybridization reveals that mRNA transcripts are only present in cells transferred to air CO2 levels. A comparison of the deduced amino acid sequence with those of other beta-CAs shows the largest degree of similarity with CA from the cyanobacterium Synechocystis (50% identity and 66% similarity). To our knowledge, this is the first identification and characterization of a mitochondrial CA from a photosynthetic organism.

  • 257.
    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.

  • 258.
    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.

  • 259.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    André, Domenique
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå S-901 83, Sweden.
    Zhang, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Bollhöner, Benjamin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Pesquet, Edouard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    METACASPASE9 modulates autophagy to confine cell death tothe target cells during Arabidopsis vascular xylem differentiation2016Inngår i: Biology Open, ISSN 2046-6390, Vol. 5, nr 2, s. 122-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We uncovered that the level of autophagy in plant cells undergoingprogrammed cell death determines the fate of the surrounding cells.Our approach consisted of using Arabidopsis thaliana cell culturescapable of differentiating into two different cell types: vasculartracheary elements (TEs) that undergo programmed cell death(PCD) and protoplast autolysis, and parenchymatic non-TEs thatremain alive. The TE cell type displayed higher levels of autophagywhen expression of the TE-specific METACASPASE9 (MC9) wasreduced using RNAi (MC9-RNAi). Misregulation of autophagy in theMC9-RNAi TEs coincided with ectopic death of the non-TEs, implyingthe existence of an autophagy-dependent intercellular signallingfrom within the TEs towards the non-TEs. Viability of the non-TEswas restored when AUTOPHAGY2 (ATG2) was downregulatedspecifically in MC9-RNAi TEs, demonstrating the importance ofautophagy in the spatial confinement of cell death. Our resultssuggest that other eukaryotic cells undergoing PCD might also needto tightly regulate their level of autophagy to avoid detrimentalconsequences for the surrounding cells.

  • 260.
    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.

  • 261.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Stael, Simon
    Vainonen, Julia P.
    Willems, Patrick
    Jin, Huiting
    Kimura, Sachie
    Van Breusegem, Frank
    Gevaert, Kris
    Wrzaczek, Michael
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Extracellular peptide Kratos restricts cell death during vascular development and stress in Arabidopsis2019Inngår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 70, nr 7, s. 2199-2210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During plant vascular development, xylem tracheary elements (TEs) form water-conducting, empty pipes by genetically regulated cell death. Cell death is prevented from spreading to non-TEs by unidentified intercellular mechanisms, downstream of METACASPASE9 (MC9)-mediated regulation of autophagy in TEs. Here, we identified differentially abundant extracellular peptides in vascular-differentiating wild-type and MC9-down-regulated Arabidopsis cell suspensions. A peptide named Kratos rescued the abnormally high ectopic non-TE death resulting from either MC9 knockout or TE-specific overexpression of the ATG5 autophagy protein during experimentally induced vascular differentiation in Arabidopsis cotyledons. Kratos also reduced cell death following mechanical damage and extracellular ROS production in Arabidopsis leaves. Stress-induced but not vascular non-TE cell death was enhanced by another identified peptide, named Bia. Bia is therefore reminiscent of several known plant cell death-inducing peptides acting as damage-associated molecular patterns. In contrast, Kratos plays a novel extracellular cell survival role in the context of development and during stress response.

  • 262.
    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.

  • 263.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Programmes of cell death and autolysis in tracheary elements: when a suicidal cell arranges its own corpse removal2014Inngår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 65, nr 5, s. 1313-1321Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Differentiation of tracheary elements (TEs) is finalized by programmed cell death (PCD) and autolysis. This review integrates TE differentiation, PCD, and autolysis in a biological and evolutionary context.Tracheary element (TE) differentiation represents a unique system to study plant developmental programmed cell death (PCD). TE PCD occurs after deposition of the secondary cell walls when an unknown signal induces tonoplast rupture and the arrest of cytoplasmic streaming. TE PCD is tightly followed by autolysis of the protoplast and partial hydrolysis of the primary cell walls. This review integrates TE differentiation, programmed cell death (PCD), and autolysis in a biological and evolutionary context. The collective evidence from the evolutionary and molecular studies suggests that TE differentiation consists primarily of a programme for cell death and autolysis under the direct control of the transcriptional master switches VASCULAR NAC DOMAIN 6 (VND6) and VND7. In this scenario, secondary cell walls represent a later innovation to improve the water transport capacity of TEs which necessitates transcriptional regulators downstream of VND6 and VND7. One of the most fascinating features of TEs is that they need to prepare their own corpse removal by expression and accumulation of hydrolases that are released from the vacuole after TE cell death. Therefore, TE differentiation involves, in addition to PCD, a programmed autolysis which is initiated before cell death and executed post-mortem. It has recently become clear that TE PCD and autolysis are separate processes with separate molecular regulation. Therefore, the importance of distinguishing between the cell death programme per se and autolysis in all plant PCD research and of careful description of the morphological, biochemical, and molecular sequences in each of these processes, is advocated.

  • 264.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Zhang, B
    Oikawa, A
    Sztojka, B
    Sathitsuksanoh, N
    Eudes, A
    Scheller, H. V.
    Tuominen, H
    The bHLH62 transcription factor is involved in the PIRIN2-dependent regulation of lignification in the xylem of Arabidopsis thalianaManuskript (preprint) (Annet vitenskapelig)
  • 265.
    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.

  • 266. 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.

  • 267. 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.

  • 268. 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)
  • 269. 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.

  • 270.
    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.

  • 271. Felten, Judith
    et al.
    Kohler, Annegret
    Morin, Emmanuelle
    Bhalerao, Rishikesh P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Palme, Klaus
    Martin, Francis
    Ditengou, Franck A
    Legue, Valerie
    The ectomycorrhizal fungus laccaria bicolor stimulates lateral root formation in poplar and arabidopsis through auxin transport and signaling2009Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 151, nr 4, s. 1991-2005Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The early phase of the interaction between tree roots and ectomycorrhizal fungi, prior to symbiosis establishment, is accompanied by a stimulation of lateral root (LR) development. We aimed to identify gene networks that regulate LR development during the early signal exchanges between poplar (Populus tremula x Populus alba) and the ectomycorrhizal fungus Laccaria bicolor with a focus on auxin transport and signaling pathways. Our data demonstrated that increased LR development in poplar and Arabidopsis (Arabidopsis thaliana) interacting with L. bicolor is not dependent on the ability of the plant to form ectomycorrhizae. LR stimulation paralleled an increase in auxin accumulation at root apices. Blocking plant polar auxin transport with 1-naphthylphthalamic acid inhibited LR development and auxin accumulation. An oligoarray-based transcript profile of poplar roots exposed to molecules released by L. bicolor revealed the differential expression of 2,945 genes, including several components of polar auxin transport (PtaPIN and PtaAUX genes), auxin conjugation (PtaGH3 genes), and auxin signaling (PtaIAA genes). Transcripts of PtaPIN9, the homolog of Arabidopsis AtPIN2, and several PtaIAAs accumulated specifically during the early interaction phase. Expression of these rapidly induced genes was repressed by 1-naphthylphthalamic acid. Accordingly, LR stimulation upon contact with L. bicolor in Arabidopsis transgenic plants defective in homologs of these genes was decreased or absent. Furthermore, in Arabidopsis pin2, the root apical auxin increase during contact with the fungus was modified. We propose a model in which fungus-induced auxin accumulation at the root apex stimulates LR formation through a mechanism involving PtaPIN9-dependent auxin redistribution together with PtaIAA-based auxin signaling.

  • 272. 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.

  • 273. 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)
  • 274.
    Fitzek, Elisabeth
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik.
    Production and characterization of mutants of UDP-glucose pyrophosphorylase2006Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    UDP-glucose pyrophosphorylase (UGPase) is a key component of carbohydrate production in plants, especially with respect to sucrose synthesis/ metabolism, by producing UDP-glucose, a key precursor to sucrose and to many polysaccharides in cell walls. UDP-glucose is also utilized in the synthesis of carbohydrate moiety of glycolipids, glycoproteins and a variety of secondary metabolites, among other functions. The UGPase enzyme may have a rate-limiting function in sugar biosynthesis, and its activity is now known to increase upon variety of abiotic stresses, with possible effects on an overall carbohydrate budget in stressed plants. The enzyme has been proposed to be regulated by (de)oligomerization and it has been estabished that only monomeric form of the enzyme is active. Based on mutant studies, the deoligomerization step (formation of monomers) was found as rate-limiting. A structural model of barley UGPase was recently suggested, based on homology to a human Antigen-X (AGX) protein that has a 40% protein sequence similarity to eukaryotic UGPase. The 3D model shows a bowl-shaped protein with three different domains: (a) N-terminal, (b) central part which includes the nucleotide binding loop (NB-loop) at the active centre and (c) C-terminal which includes an insertion loop (I-loop) that is possibly involved in dimer formation and stabilization. In this study, the model was used as a testable blueprint to verify details of the barley enzyme catalysis and substrate binding, as well as oligomerization process.  In order to test the model, site-directed mutagenesis approaches and heterologous (E. coli) expression system were used to produce several UGPase mutants: Del-NB, lacking 4 amino acids (aa) at the NB region; Del-I-4 and Del-I-8, lacking respectively 4 and 8 aa of the I-loop; and Y192A, by replacing an active-site tyrosine into alanine. The Y192A mutant had about half the apparent activity of the wild-type (wt), whereas Del-I-8 and Del-I-4 had only 0.5 and 0.2 % activity, respectively, of the wt, and Del-NB showed no activity at all. Based on native-PAGE, both Y192A and Del-NB mutants had similar oligomerization status as the wt, i.e. existing as monomer only or a mixture of monomer, dimer and higher order oligomers, depending on incubation conditions. Both Del-I-8 and Del-I-4 were present in all conditions as higher order oligomers. Whereas Y192A mutant had similar Kms with both substrates as the wt protein, significant difference between the Del-I-4 and Del-I-8 mutants and wt could be detected. Both mutants had approximately 16-fold higher Kms for UDP-glucose, and the Kms with PPi were 735- and 1500-fold higher for Del-I-4 and Del-I-8, respectively, when compared to wt.The conclusion of those results: (A) Tyr-192 is not essential for activity and is not involved in substrate binding and/ or oligomerization of the enzyme. (B) The NB-loop is essential for catalysis, as evidenced by a complete lack of activity of the Del-NB mutant, and is not involved in oligomerization. On the other hand, (C) the region corresponding to central part of I-loop is located in the model far from active center, but deletion in this region does affect very strongly both catalysis and substrate binding parameters. This can be explained by the involvement of I-loop in formation of dimers (inactive) from monomers (active), as earlier proposed. Apparently, the Del-I-4 and Del-I-8 mutations lead to an enzyme form with a very high oligomerization ability. This affects both Kms and Vmaxs of the Del-I mutants. Taken together the results verify the essentiality of NB-loop for catalysis support the involvement of I-loop region in oligomerization and, overall, the importance of oligomerization status for enzymatic performance of UGPase.

  • 275.
    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.

  • 276. 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.

  • 277.
    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.

  • 278.
    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))
  • 279.
    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.

  • 280.
    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))
  • 281.
    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.

  • 282.
    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.

  • 283.
    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.

  • 284. 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.

  • 285. 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.

  • 286. 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.

  • 287. 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.

  • 288. 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.

  • 289.
    Ganeteg, U.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik.
    Klimmek, F.
    Jansson, S.
    Lhca5 - an LHC-type protein associated with photosystem I.Artikkel i tidsskrift (Fagfellevurdert)
  • 290.
    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)
  • 291.
    Ganeteg, Ulrika
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    The light-harvesting antenna of higher plant photosystem I2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    During photosynthesis, two multi-protein complexes, photosystems (PS) I and II work in tandem to convert the light-energy absorbed by the light-harvesting antennae into chemical energy, which is subsequently used to assimilate atmospheric carbon dioxide into organic carbon compounds. This is the main nutritional basis for life on Earth.

    The photosynthetic antenna of higher plants comprises at least ten different pigment-binding proteins (LHC), which play important roles in photosynthesis. Chlorophyll and carotenoid molecules associated with the LHC proteins are organised into an array, which can be modulated, thereby optimising light-harvesting processes and protection against oxidative damage under conditions of excessive light absorption. All ten LHC proteins have been conserved through eons of evolution, suggesting that there are strong evolutionary pressures to retain all ten proteins, and hence that each protein has a unique function.

    The light-harvesting antenna of higher plant PSI consists of at least four proteins, Lhca1-4, collectively called LHCI. By constructing transgenic Arabidopsis thaliana plants in which each Lhca gene has been individually repressed or knocked-out, a collection of plants with different Lhca protein contents was obtained. The objective was to use these plants to study the structure, function and regulation of the Lhca proteins in vivo. The major findings of this work are as follows.

    Removing single Lhca proteins influenced the stability of the other Lhca proteins, showing that there is a high degree of inter-dependency between the polypeptides in LHCI, and hence that a full set of Lhca proteins is important for maintaining the structural integrity of LHCI. This has provided insight into the organisation of LHCI by revealing clues about the relative positions of each Lhca protein in the antenna complex. The physiological consequences of removing individual Lhca proteins were dependent on the degree of antenna depletion. Plants with relatively small antenna changes could compensate, to some extent, for the loss of LHCI, while larger depletions had profound effects on whole plant resulting in growth reductions.

    The fitness of each Lhca plant was assessed by measuring their seed production in the harsh conditions in the field. We found that all Lhca-deficient plants produced fewer seeds under some conditions, with seed-production compared to wild type varying between 10-80% depending on the extent of LHCI reduction. Therefore, we conclude that each Lhca protein is important for plant fitness, and hence for the survival of the species.

    PSI is characterised by a pool of pigments absorbing light in the red end of the solar visible spectrum, thought to be especially important for plants in dense vegetation systems where the incident light is enriched in wavelengths higher than 690 nm. A majority of these pigments are situated on LHCI and, based on in-vitro studies, were thought to be mainly associated with Lhca4. Using our plants, we have established that red pigments are indeed present on all Lhca proteins and that these pigments become even more red upon association with PSI.

  • 292.
    Ganeteg, Ulrika
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Klimmek, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Ihalainen, J.
    Ruban, A.
    Benson, S.
    van Roon, H.
    Scheller, H.V.
    Horton, P.
    Dekker, J.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Structure and function of the lightharvesting complex of higher plant photosystem IManuskript (preprint) (Annet vitenskapelig)
  • 293.
    Ganeteg, Ulrika
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Klimmek, Frank
    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).
    Lhca5--an LHC-type protein associated with photosystem I.2004Inngår i: Plant Molecular Biology, ISSN 0167-4412, Vol. 54, nr 5, s. 641-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The light-harvesting antenna of higher plant photosystem (PS) I is known to be composed of four different types of light-harvesting complex (LHC) proteins (Lhca1–4). However, the genomic sequence of Arabidopsis thaliana contains open reading frames coding for two additional LHC type proteins (Lhca5–6) that are presumably associated with PSI. While Lhca6 might not be expressed at all, ESTs have been detected for the Lhca5 gene in Arabidopsis and a number of other plant species. Here we demonstrate the presence of the Lhca5 gene product in the thylakoid membrane of Arabidopsis as an additional type of Lhca-protein associated with PSI. Lhca5 seems to be regulated differently from the other LHC proteins since Lhca5 mRNA levels increase under high light conditions. Analyses reported here of Lhca5 in plants lacking individual Lhca1–4 proteins show that it is more abundant in plants lacking Lhca1/4, and suggest that it interacts in a direct physical fashion with Lhca2 or Lhca3. We propose that Lhca5 binds chlorophylls in a similar fashion to the other Lhca proteins and is associated with PSI only in sub-stoichiometric amounts.

  • 294.
    Ganeteg, Ulrika
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Külheim, Carsten
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Andersson, Jenny
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Is each light-harvesting complex protein important for plant fitness?2004Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 134, nr 1, s. 502-509Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many of the photosynthetic genes are conserved among all higher plants, indicating that there is strong selective pressure to maintain the genes of each protein. However, mutants of these genes often lack visible growth phenotypes, suggesting that they are important only under certain conditions or have overlapping functions. To assess the importance of specific genes encoding the light-harvesting complex (LHC) proteins for the survival of the plant in the natural environment, we have combined two different scientific traditions by using an ecological fitness assay on a set of genetically modified Arabidopsis plants with differing LHC protein contents. The fitness of all of the LHC-deficient plants was reduced in some of the growth environments, supporting the hypothesis that each of the genes has been conserved because they provide ecological flexibility, which is of great adaptive value given the highly variable conditions encountered in nature.

  • 295.
    Garcia Cerdan, Jose Gines
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sveshnikov, Dmitry
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Dewez, David
    Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720-3102, USA.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Schröder, Wolfgang
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Antisense inhibition of the PsbX protein affects PSII integrity in the higher plant Arabidopsis Thaliana2009Inngår i: Plant and Cell Physiology, ISSN 0032-0781, E-ISSN 1471-9053, Vol. 50, nr 2, s. 191-202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PSII, the oxygen-evolving complex of photosynthetic organisms, contains an intriguingly large number of low molecular weight proteins. PsbX, one of these proteins, is ubiquitous in PSII complexes of cyanobacteria and plants. In previous studies, deletion of the PsbX protein in cyanobacteria has not resulted in clear phenotypic changes. Here we report the construction of an antisense (AS-PsbX) line in Arabidopsis thaliana with <10% of wild-type PsbX levels. AS-PsbX plants are capable of photoautotrophic growth, but biochemical, biophysical and immunological evidence demonstrates that reduction of PsbX contents leads to reduced levels of functional assembled PSII core complexes, while the light-harvesting antennae are not affected. In addition, levels of phosphorylation of the core proteins D1, D2 and CP43 are severely reduced in the antisense plants relative to their wild-type counterparts. We conclude that PsbX is important for accumulation of functional PSII.

  • 296.
    Garci­a-Lorenzo, Maribel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sjödin, Andreas
    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).
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Protease gene families in Populus and Arabidopsis2006Inngår i: BMC Plant Biology, ISSN 1471-2229, E-ISSN 1471-2229, Vol. 6, nr 30, s. 1-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proteases play key roles in plants, maintaining strict protein quality control and degrading specific sets of proteins in response to diverse environmental and developmental stimuli. Similarities and differences between the proteases expressed in different species may give valuable insights into their physiological roles and evolution. RESULTS: We have performed a comparative analysis of protease genes in the two sequenced dicot genomes, Arabidopsis thaliana and Populus trichocarpa by using genes coding for proteases in the MEROPS database 1 for Arabidopsis to identify homologous sequences in Populus. A multigene-based phylogenetic analysis was performed. Most protease families were found to be larger in Populus than in Arabidopsis, reflecting recent genome duplication. Detailed studies on e.g. the DegP, Clp, FtsH, Lon, rhomboid and papain-Like protease families showed the pattern of gene family expansion and gene loss was complex. We finally show that different Populus tissues express unique suites of protease genes and that the mRNA levels of different classes of proteases change along a developmental gradient. CONCLUSION: Recent gene family expansion and contractions have made the Arabidopsis and Populus complements of proteases different and this, together with expression patterns, gives indications about the roles of the individual gene products or groups of proteases.

  • 297.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ADENYLATE RATIOS IN THE CYTOSOL, CHLOROPLASTS AND MITOCHONDRIA OF BARLEY LEAF PROTOPLASTS DURING PHOTOSYNTHESIS AT DIFFERENT CARBON-DIOXIDE CONCENTRATIONS1987Inngår i: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 212, nr 1, s. 114-118Artikkel i tidsskrift (Fagfellevurdert)
  • 298.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    METABOLITE LEVELS IN THE CHLOROPLAST AND EXTRACHLOROPLAST COMPARTMENTS OF BARLEY LEAF PROTOPLASTS DURING THE INITIAL PHASE OF PHOTOSYNTHETIC INDUCTION1993Inngår i: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1183, nr 2, s. 327-332Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metabolite levels were determined in the chloroplast and extrachloroplast compartments of barley protoplasts during photosynthetic induction using rapid fractionation by membrane filtration. This method allowed studies with a high time resolution the first determination of subcellular metabolite content bring made after only 0.3 s. Upon illumination, dark-adapted protoplasts exhibited a 1 min lag phase prior to commencement of oxygen evolution, and the maximum rate was reached after 4 to 5 min. In contrast to oxygen evolution, the ATP/ADP ratio in the chloroplasts increased from 1 to 2 within 0.5 s and reached a maximum of about 5 after 2 s. There was a dramatic increase in the extrachloroplastic ATP/ADP ratio within a few seconds, reaching a maximum after about 15 s. During the initial phase of photosynthetic induction, the subcellular ATP/ADP ratios were very similar in photorespiratory (low CO,) and non-photorespiratory (high CO,) conditions. The ATP/ADP ratios in both the chloroplast and extrachloroplast compartments remained high until photosynthetic oxygen evolution started and then decreased when the photosynthetic rate reached its maximum. In steady-state photosynthesis the subcellular ATP/ADP ratios were considerably higher under photorespiratory conditions as compared to non-photorespiratory conditions. During the initial phase of photosynthetic induction, 3-phosphoglycerate decreased and triose phosphates increased both in the chloroplast and extrachloroplast compartments. The changes in these metabolites are consistent with a 3-phosphoglycerate/triose phosphate shuttle using the phosphate translocator as the means to supply ATP to the cytosol during photosynthetic induction.

  • 299.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Preparation of leaf mitochondria and studies on mitochondrial photorespiratory reactions1981Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    A procedure for the preparation of spinach leaf mitochondria was developed. The procedure combines differential centrifugation, partition in dextran- polyethyleneglycol two-phase system and Percoli density gradient centri- fugation. The different steps separate the material mainly according to size, surface properties and density, respectively. No chlorophyll was present in the final mitochondrial preparation and the mitochondria were also markedly enriched relative to peroxisomes and microsomes as esti­mated from the recovery of marker enzymes. The latency of enzyme activities was used to study the apparent intactness of the mitochondrial membranes. These measurements showed that both the inner and outer mitochondrial membranes were more than 90 % intact. The mitochondria were also functionally intact since the coupling between respiration and oxidative phosphorylation was retained.

    The purity of the preparation made it possible to study cytochromes from leaf mitochondria. The cytochrome content of stalk and leaf mitochondria was measured in order to compare mitochondria from photosynthesizing and non-photosynthesizing tissue. The measurements were performed by difference spectroscopy both at room temperature and at liquid nitrogen temperature. Qualitatively the cytochrome content in mitochondria from stalks and leaves was identical. Quantiatively leaf mitochondria contained,on a protein basis, only half the amount of the different cytochromes as compared to stalk mitochondria. The relative content of the different cytochromes was, however, similar suggesting that the composition of the respiratory chain was the same.

    The photorespiratory conversion of glycine to serine takes place in the mitochondria and involves oxidative decarboxylation of glycine. The ability to oxidize glycine via the respiratory chain was present in spinach leaf mitochondria, but absent in mitochondria prepared from roots, stalks and leaf veins from the same plants. This confirmed the specific localization of the glycine oxidizing activity to photosyntheticaliy active tissue, as suggested by studies with other plant material.

    The conversion of glycine to serine is a complex reaction depending on the combined action of two enzymes: glycine decarboxylase and serine hydroxymethyltransferase. The effect of inhibitors on the serine hydroxy­methyl transferase activity and the rate of the glycine bicarbonate exchange reaction associated with glycine decarboxylase was studied. These reactions represent partial steps in the conversion of glycine to serine and the aim was to investigate the site of inhibition for the different inhibitors, namely, isonicotinyl hydrazide (a pyridoxa!phosphate antagonist), amino- acetonitrile, glycinehydroxamate (glycine analogues) and cyanide. The results showed that these inhibitors had a complex pattern of inhibition. The same inhibitor affected more than one site and often with an apparently different mechanism. It was, however, found that aminoacetonitrile at low concentrations specifically inhibited glycine decarboxylase and that cyanide specifically inhibited serine hydroxymethyltransferase.

  • 300.
    Gardeström, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bergman, A
    Ericson, I
    Oxidation of Glycine via the Respiratory Chain in Mitochondria Prepared from Different Parts of Spinach.1980Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 65, nr 2, s. 389-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

3456789 251 - 300 of 1158
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf