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  • 1. Andersson, A
    et al.
    Wallberg, P
    Nordback, J
    Bergqvist, P A
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Effect of nutrient enrichment on the distribution and sedimentation of polychlorinated biphenyls (PCBs) in seawater1998Ingår i: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 377, s. 45-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of nutrient enrichment on the distribution of polychlorinated biphenyl's (PCBs) in the microbial food web and the residence time of PCBs in seawater was studied in an experimental mesocosm system. Two 5 m high temperature and light controlled mesocosm tubes (empty set = 0.5 m) were filled with seawater from the northern Baltic Sea. Inorganic phosphorus and nitrogen were added daily to one mesocosm, while the other served as a control. Experiments were conducted at 5, 10 and 20 degrees C. Three C-14-labelled PCBs of different degree of chlorination were added to subsamples of the mesocosms: 4-chlorobiphenyl (MCB), IUPAC # 3, 2,2',5,5'-tetrachlorobiphenyl (TCB), IUPAC # 52 and 2,2',4,4',5,5'-hexachlorobiphenyl (HCB) IUPAC # 153. The biomasses and growth rates of the microorganisms as well as the sedimentation rate of particulate organic material increased with nutrient enrichment. The size distribution of the microorganisms changed with nutrient status, from dominance of picoplankton (< 2 mu m) in the control towards increased importance of micro (> 10 mu m) and nanoplankton (2-10 mu m) in nutrient enrichment. The specific growth rate of the bacterial community was found to be more temperature dependent than that of the phytoplankton community. The relative proportion of PCBs in the > 2 mu m fraction was observed to be in the order MCB < TCB < HCB, while the opposite distribution prevailed in the < 2 mu m fraction. We hypothesize that this is due to the combined effect of the different K-ow values of the PCBs and a different composition of the particulate organic carbon in the > 2 mu m and < 2 mu m fractions (e.g. different lipid composition). The residence time of the PCBs in the mesocosm generally decreased with nutrient enrichment, but was dependent on the degree of chlorination of the PCB. Our results indicate that the transport of organic pollutants up through the food web is more important in nutrient poor than in nutrient rich waters and that the importance of sedimentation is higher in eutrophic ecosystems.

  • 2.
    Andersson, Agneta
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hagström, Åke
    Vertical transport of lipid in seawater1993Ingår i: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 98, nr 1-2, s. 149-155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lipids in seawater act as solvents and transporters of lipophilic organic pollutants. To investigate a possible transport route of lipophilic pollutants, the vertical flux of lipid was quantified during an annual cycle in the northern Baltic Sea. The lipid content in both sedimenting material and different size fractions of seawater was analyzed. During the year, 8 g lipid m-2 sedimented out from the photic zone to the benthic system. The sedimentation of lipid accounted for 300 to 400 % of the average standing stock of pelagic lipid and was concentrated in the spring bloom period (April-June) when 70 % of the total lipid sedimentation occurred. About 30 % of the produced pelagic lipid settled out from the system. In seawater the lipid maximum occurred at the end of the spring bloom, shortly after nutrient depletion, indicating a stress response in the algae. Since lipid sedimentation is concentrated in the spring bloom, removal of lipophilic organic pollutants may be important during this period.

  • 3.
    Birve, Simon
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Johansson, L B A
    Secondary structure of NADPH: protochlorophyllide oxidoreductase examined by circular dichroism and prediction methods1996Ingår i: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 317, nr 2, s. 549-555Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To study the secondary structure of the enzyme NADPH:protochlorophyllide oxidoreductase (PCOR), a novel method of enzyme isolation was developed. The detergent isotridecyl poly(ethylene glycol) ether (Genapol X-080) selectively solubilizes the enzyme from a prolamellar-body fraction isolated from wheat (Triticum aestivum L.). The solubilized fraction was further purified by ion-exchange chromatography. The isolated enzyme was studied by fluorescence spectroscopy at 77 K, and by CD spectroscopy. The fluorescence-emission spectra revealed that the binding properties of the substrate and co-substrate were preserved and that photo-reduction occurred. The CD spectra of PCOR were analysed for the relative amounts of the secondary structures, alpha-helix, beta-sheet, turn and random coil. The secondary structure composition was estimated to be 33% alpha-helix, 19% beta-sheet, 20% turn and 28% random coil. These values are in agreement with those predicted by the Predict Heidelberg Deutschland and self-optimized prediction method from alignments methods. The enzyme has some amino acid identity with other NADPH-binding enzymes containing the Rossmann fold. The Rossmann-fold fingerprint motif is localized in the N-terminal region and at the expected positions in the predicted secondary structure. It is suggested that PCOR is anchored to the interfacial region of the membrane by either a beta-sheet or an alpha-helical region containing tryptophan residues. A hydrophobic loop-region could also be involved in membrane anchoring.

  • 4. BRENTEL, I
    et al.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    LINDBLOM, G
    PHASE-EQUILIBRIA OF MIXTURES OF PLANT GALACTOLIPIDS - THE FORMATION OF A BICONTINUOUS CUBIC PHASE1985Ingår i: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 812, nr 3, s. 816-826Artikel i tidskrift (Refereegranskat)
  • 5. Hendrickson, Luke
    et al.
    Vlcková, Alexandra
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Huner, Norman
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Cold acclimation of the Arabidopsis dgd1 mutant results in recovery from photosystem I-limited photosynthesis.2006Ingår i: FEBS Letters, ISSN 0014-5793, Vol. 580, nr 20, s. 4959-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We compared the thylakoid membrane composition and photosynthetic properties of non- and cold-acclimated leaves from the dgd1 mutant (lacking >90% of digalactosyl–diacylglycerol; DGDG) and wild type (WT) Arabidopsis thaliana. In contrast to warm grown plants, cold-acclimated dgd1 leaves recovered pigment-protein pools and photosynthetic function equivalent to WT. Surprisingly, this recovery was not correlated with an increase in DGDG. When returned to warm temperatures the severe dgd1 mutant phenotype reappeared. We conclude that the relative recovery of photosynthetic activity at 5 °C resulted from a temperature/lipid interaction enabling the stable assembly of PSI complexes in the thylakoid.

  • 6. Ivanov, Alexander G
    et al.
    Hendrickson, Luke
    Krol, Marianna
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Huner, Norman P A
    Digalactosyl-diacylglycerol deficiency impairs the capacity for photosynthetic intersystem electron transport and state transitions in Arabidopsis thaliana due to photosystem I acceptor-side limitations.2006Ingår i: Plant Cell Physiology, ISSN 0032-0781, Vol. 47, nr 8, s. 1146-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Compared with wild type, the dgd1 mutant of Arabidopsis thaliana exhibited a lower amount of PSI-related Chl–protein complexes and lower abundance of the PSI-associated polypeptides, PsaA, PsaB, PsaC, PsaL and PsaH, with no changes in the levels of Lhca1–4. Functionally, the dgd1 mutant exhibited a significantly lower light-dependent, steady-state oxidation level of P700 (P700+) in vivo, a higher intersystem electron pool size, restricted linear electron transport and a higher rate of reduction of P700+ in the dark, indicating an increased capacity for PSI cyclic electron transfer compared with the wild type. Concomitantly, the dgd1 mutant exhibited a higher sensitivity to and incomplete recovery of photoinhibition of PSI. Furthermore, dgd1 exhibited a lower capacity to undergo state transitions compared with the wild type, which was associated with a higher reduction state of the plastoquinone (PQ) pool. We conclude that digalactosyl-diacylglycerol (DGDG) deficiency results in PSI acceptor-side limitations that alter the flux of electrons through the photosynthetic electron chain and impair the regulation of distribution of excitation energy between the photosystems. These results are discussed in terms of thylakoid membrane domain reorganization in response to DGDG deficiency in A. thaliana.

  • 7. Ivanov, Alexander G
    et al.
    Krol, Marianna
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik. Umeå Plant Science Centre.
    Sane, Prafullachandra Vishnu
    Sveshnikov, Dmitry
    Park, Youn-Il
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik. Umeå Plant Science Centre.
    Huner, Norman P A
    The induction of CP43' by iron-stress in Synechococcus sp. PCC 7942 is associated with carotenoid accumulation and enhanced fatty acid unsaturation.2007Ingår i: Biochimica et Biophysica Acta, ISSN 0006-3002, Vol. 1767, nr 6, s. 807-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Comparative lipid analysis demonstrated reduced amount of PG (50%) and lower ratio of MGDG/DGDG in iron-stressed Synechococcus sp. PCC 7942 cells compared to cells grown under iron sufficient conditions. In parallel, the monoenoic (C:1) fatty acids in MGDG, DGDG and PG increased from 46.8%, 43.7% and 45.6%, respectively in control cells to 51.6%, 48.8% and 48.7%, respectively in iron-stressed cells. This suggests increased membrane dynamics, which may facilitate the diffusion of PQ and keep the PQ pool in relatively more oxidized state in iron-stressed compared to control cells. This was confirmed by chlorophyll fluorescence and thermoluminescence measurements. Analysis of carotenoid composition demonstrated that the induction of isiA (CP43′) protein in response to iron stress is accompanied by significant increase of the relative abundance of all carotenoids. The quantity of carotenoids calculated on a Chl basis increased differentially with nostoxanthin, cryptoxanthin, zeaxanthin and β-carotene showing 2.6-, 3.1-, 1.9- and 1.9-fold increases, respectively, while the relative amount of caloxanthin was increased only by 30%. HPLC analyses of the pigment composition of Chl–protein complexes separated by non-denaturating SDS-PAGE demonstrated even higher relative carotenoids content, especially of cryptoxanthin, in trimer and monomer PSI Chl–protein complexes co-migrating with CP43′ from iron-stressed cells than in PSI complexes from control cells where CP43′ is not present. This implies a carotenoid-binding role for the CP43′ protein which supports our previous suggestion for effective energy quenching and photoprotective role of CP43′ protein in cyanobacteria under iron stress.

  • 8. Ivanov, Alexander G
    et al.
    Krol, Marianna
    Sveshnikov, Dmitry
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik. Umeå Plant Science Centre.
    Sandström, Stefan
    Koochek, Maryam
    Park, Youn-Il
    Vasil'ev, Sergej
    Bruce, Doug
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik. Umeå Plant Science Centre.
    Huner, Norman P A
    Iron deficiency in cyanobacteria causes monomerization of photosystem I trimers and reduces the capacity for state transitions and the effective absorption cross section of photosystem I in vivo.2006Ingår i: Plant Physiology, ISSN 0032-0889, Vol. 141, nr 4, s. 1436-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The induction of the isiA (CP43') protein in iron-stressed cyanobacteria is accompanied by the formation of a ring of 18 CP43' proteins around the photosystem I (PSI) trimer and is thought to increase the absorption cross section of PSI within the CP43'-PSI supercomplex. In contrast to these in vitro studies, our in vivo measurements failed to demonstrate any increase of the PSI absorption cross section in two strains (Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803) of iron-stressed cells. We report that iron-stressed cells exhibited a reduced capacity for state transitions and limited dark reduction of the plastoquinone pool, which accounts for the increase in PSII-related 685 nm chlorophyll fluorescence under iron deficiency. This was accompanied by lower abundance of the NADP-dehydrogenase complex and the PSI-associated subunit PsaL, as well as a reduced amount of phosphatidylglycerol. Nondenaturating polyacrylamide gel electrophoresis separation of the chlorophyll-protein complexes indicated that the monomeric form of PSI is favored over the trimeric form of PSI under iron stress. Thus, we demonstrate that the induction of CP43' does not increase the PSI functional absorption cross section of whole cells in vivo, but rather, induces monomerization of PSI trimers and reduces the capacity for state transitions. We discuss the role of CP43' as an effective energy quencher to photoprotect PSII and PSI under unfavorable environmental conditions in cyanobacteria in vivo.

  • 9.
    Jansson, Stefan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Gustafsson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    THE RAPIDLY PHOSPHORYLATED 25-KDA POLYPEPTIDE OF THE LIGHT-HARVESTING COMPLEX OF PHOTOSYSTEM-II IS ENCODED BY THE TYPE-2 CAB-II GENES1990Ingår i: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1019, nr 2, s. 110-114Artikel i tidskrift (Refereegranskat)
  • 10. RYBERG, M
    et al.
    SANDELIUS, AS
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    LIPID-COMPOSITION OF PROLAMELLAR BODIES AND PROTHYLAKOIDS OF WHEAT ETIOPLASTS1983Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 57, nr 4, s. 555-560Artikel i tidskrift (Refereegranskat)
  • 11. SANDELIUS, AS
    et al.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    LOCALIZATION OF GALACTOLIPID BIOSYNTHESIS IN ETIOPLASTS ISOLATED FROM DARK-GROWN WHEAT (TRITICUM-AESTIVUM L)1984Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 76, nr 4, s. 1041-1046Artikel i tidskrift (Refereegranskat)
  • 12.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Brain, Anthony P R
    Williams, W Patrick
    The relationship between different spectral forms of the protochlorophyllide oxidoreductase complex and the structural organisation of prolamellar bodies isolated from Zea mays2011Ingår i: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, Vol. 108, nr 1, s. 47-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Incubation of prolamellar bodies (PLB) in high-salt media leads to changes in PLB structure and properties of their protochlorophyllide oxidoreductase-protochlorophyllide (POR-PChlide) complex. The paracrystalline organisation typical of PLB is disrupted and NADPH dissociates from photoconvertible POR-PChlide, with absorption maxima at 640 and 650 nm (POR-PChlide ( 640/650 )), and a non-photoconvertible form, with absorption maxima at 635 nm (POR-PChlide ( 635 )), is formed. These effects are strongly dependent on the valence of the cation of the perturbing salt, indicating that they involve surface double layers effects. They are also influenced by the nature of the anion and by high concentrations of non-electrolytes, suggesting the involvement of surface hydration effects. The structural changes are largely, if not entirely, independent of the presence of excess NADPH. Changes to the POR-PChlide complex, however, are strongly inhibited by excess NADPH suggesting that the two sets of changes may not be causally linked. As long as the disruption is not too great, the structural changes seen on incubation of PLB in high salt media lacking excess NADPH are reversed on removal of the high salt perturbation. This reversal is independent of the presence or absence of added NADPH. Reformation of photoconvertible POR-PChlide, however, requires the presence of NADPH. The reformation of paracrystalline PLB in the absence of NADPH strongly indicates that preservation of PLB structure, in isolated PLB preparations at least, is independent of the presence or absence of POR-PChlide ( 650 ).

  • 13.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Campbell, D
    Membrane lipid composition of the unusual cyanobacterium Gloeobacter violaceus sp PCC 7421, which lacks sulfoquinovosyl diacylglycerol1996Ingår i: Archives of Microbiology, ISSN 0302-8933, E-ISSN 1432-072X, Vol. 166, nr 2, s. 132-135Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gloeobacter violaceus sp. PCC 7421 is an unusual cyanobacterium with only one cellular membrane, which lacks the thylakoid membranes found in other oxygenic photosynthetic organisms. The cell membrane lipids in G. violaceus sp. PCC 7421 are monogalactosyl diacylglycerol, digalactosyl diacylglycerol, phosphatidyl glycerol and phosphatidic acid in the molar proportion of 51, 24, 18 and 4% respectively. This lipid composition resembles that of the cell membrane from other cyanobacteria, but completely lacks sulfoquinovosyl diacylglycerol. This lack of sulfoquinovosyl diacylglycerol is exceptional for a photosynthetic membrane. The membrane lipids are esterified to 14:0, 16:0, 16:1, 18:0, 18:1, 18:2 and alpha 18:3 fatty acids.

  • 14.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    JACKSON, AO
    LIPID-COMPOSITION OF SONCHUS YELLOW NET VIRUS1983Ingår i: Journal of General Virology, ISSN 0022-1317, E-ISSN 1465-2099, Vol. 64, nr JUL, s. 1607-1613Artikel i tidskrift (Refereegranskat)
  • 15.
    Selstam, Eva
    et al.
    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).
    EFFECTS OF FROST HARDENING ON THE COMPOSITION OF GALACTOLIPIDS AND PHOSPHOLIPIDS OCCURRING DURING ISOLATION OF CHLOROPLAST THYLAKOIDS FROM NEEDLES OF SCOTS PINE1985Ingår i: Plant Science, ISSN 0168-9452, E-ISSN 1873-2259, Vol. 42, nr 1, s. 41-48Artikel i tidskrift (Refereegranskat)
  • 16.
    Selstam, Eva
    et al.
    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).
    GALACTOLIPID BIOSYNTHESIS IN CHLOROPLASTS OF NONHARDENED AND FROST-HARDENED SEEDLINGS OF SCOTS PINE1990Ingår i: Plant physiology and biochemistry (Paris), ISSN 0981-9428, E-ISSN 1873-2690, Vol. 28, nr 4, s. 477-483Artikel i tidskrift (Refereegranskat)
  • 17.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    SANDELIUS, AS
    A COMPARISON BETWEEN PROLAMELLAR BODIES AND PROTHYLAKOID MEMBRANES OF ETIOPLASTS OF DARK-GROWN WHEAT CONCERNING LIPID AND POLYPEPTIDE COMPOSITION1984Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 76, nr 4, s. 1036-1040Artikel i tidskrift (Refereegranskat)
  • 18.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Schelin, J
    Brain, T
    Williams, W P
    The effects of low pH on the properties of protochlorophyllide oxidoreductase and the organization of prolamellar bodies of maize (Zea mays)2002Ingår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 269, nr 9, s. 2336-2346Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Prolamellar bodies (PLB) contain two photochemically active forms of the enzyme protochlorophyllide oxidoreductase POR-PChlide(640) and POR-PChlide(650) (the spectral forms of POR-Chlide complexes with absorption maxima at the indicated wavelengths). Resuspension of maize PLB in media with a pH below 6.8 leads to a rapid conversion of POR-PChlide(650) to POR-PChlide(640) and a dramatic re-organization of the PLB membrane system. In the absence of excess NADPH, the absorption maximum of the POR complex undergoes a further shift to about 635 nm. This latter shift is reversible on the re-addition of NADPH with a half-saturation value of about 0.25 mm NADPH for POR-PChlide(640) reformation. The disappearance of POR-PChlide(650) and the reorganization of the PLB, however, are irreversible. Restoration of low-pH treated PLB to pH 7.5 leads to a further breakdown down of the PLB membrane and no reformation of POR-PChlide(650) . Related spectral changes are seen in PLB aged at room temperature at pH 7.5 in NADPH-free assay medium. The reformation of POR-PChlide(650) in this system is readily reversible on re-addition of NADPH with a half-saturation value about 1.0 mum. Comparison of the two sets of changes suggest a close link between the stability of the POR-PChlide(650) , membrane organization and NADPH binding. The low-pH driven spectral changes seen in maize PLB are shown to be accelerated by adenosine AMP, ADP and ATP. The significance of this is discussed in terms of current suggestions of the possible involvement of phosphorylation (or adenylation) in changes in the aggregational state of the POR complex.

  • 19.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysiologisk botanik. Umeå Plant Science Centre.
    Schelin, Jenny
    Williams, W Patrick
    Brain, Anthony P R
    Structural organisation of prolamellar bodies (PLB) isolated from Zea mays. Parallel TEM, SAXS and absorption spectra measurements on samples subjected to freeze-thaw, reduced pH and high-salt perturbation.2007Ingår i: Biochimica et Biophysica Acta, ISSN 0006-3002, Vol. 1768, s. 2235-2245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Well-organised PLB gives rise to a X-ray diffraction pattern overlaid by a scattering pattern arising from individual tubules within less well-organised regions of the lattice. TEM and SAXS measurements were used to characterise the structural changes in PLB subjected to perturbation by freeze–thaw, exposure to pH 6.5, or resuspension in high-salt media. Comparison of SAXS patterns measured, before and after structural perturbation allows the separation of the contributions from ordered and disordered PLB. The diffraction pattern is shown to be based on a diamond cubic (Fd3m) lattice of unit cell a = 78 nm. Freeze–thaw and high-salt disruption lead to the breakdown of ordered PLB into disordered tubules of similar dimensions to those making up the original PLB lattice. Their scattering patterns suggest that they are approximately 26 nm in diameter with a central lumen about 16 nm in diameter. The tubules formed at pH 6.5 are appreciably narrower, probably reflecting changes in the pattern of ionisation of charged groups at the membrane surface. Absorption spectra of PLB in media containing different concentrations of salts indicated that the structural and spectral changes are related. NADPH, have a significant role in the protection of POR-PChlide650 but to have only a relatively small effect on the preservation of PLB organisation indicating that the retention of POR-PChlide650 in isolated PLB preparations is a poor guide to their structural integrity.

  • 20.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    WIDELL, A
    CHARACTERIZATION OF PROLAMELLAR BODIES, FROM DARK-GROWN SEEDLINGS OF SCOTS PINE, CONTAINING LIGHT-DEPENDENT AND NADPH-DEPENDENT PROTOCHLOROPHYLLIDE OXIDOREDUCTASE1986Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 67, nr 3, s. 345-352Artikel i tidskrift (Refereegranskat)
  • 21.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    WIDELL, A
    JOHANSSON, LBA
    A COMPARISON OF PROLAMELLAR BODIES FROM WHEAT, SCOTS PINE AND JEFFREY PINE - PIGMENT SPECTRA AND PROPERTIES OF PROTOCHLOROPHYLLIDE OXIDOREDUCTASE1987Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 70, nr 2, s. 209-214Artikel i tidskrift (Refereegranskat)
  • 22.
    Selstam, Eva
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    WIDELLWIGGE, A
    HYDROPHOBICITY OF PROTOCHLOROPHYLLIDE OXIDOREDUCTASE, CHARACTERIZED BY MEANS OF TRITON X-114 PARTITIONING OF ISOLATED ETIOPLAST MEMBRANE-FRACTIONS1989Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 77, nr 3, s. 401-406Artikel i tidskrift (Refereegranskat)
  • 23. Seyedi, M
    et al.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Timko, M P
    Sundqvist, C
    The cytokinin 2-isopentenyladenine causes partial reversion to skotomorphogenesis and induces formation of prolamellar bodies and protochlorophyllide(657) in the lip1 mutant of pea2001Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 112, nr 2, s. 261-272Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When grown in darkness the photomorphogenic lip1 mutant of pea (Pisum sativum L.) has a slender stem, expanded leaves, prolamellar body (PLB) lacking plastids with the size of chloroplasts and a low level of phytochrome A. The lack of PLBs in a dark-grown material (lip1) created a possibility to further study the regulation of their formation in relation to plant development, Inclusion of a cytokinin, 2-isopentenyladenine (2iP), in a medium supporting growth of the pea seedlings in darkness was found to reduce epicotyl length in the wild type. In lip1 the formation of a slender stem was inhibited and a short epicotyl developed. Furthermore, leaf expansion was inhibited, the plastid size reduced and the formation of PLBs induced. The PLB formation in lip1 was not accompanied by an increase in the amount of protochlorophyllide (Pchlide) or Pchilde oxidoreductase (POR), In the presence of 2iP the level of phytochrome A protein was increased in lip1 and the FOR mRNA levels decreased in both lip1 and wild-type plants. The chloroplast characteristic trans-3-hexadecenoate acyl group of phosphatidylglycerol, present in the plastids of dark-grown lip1, was not influenced by 2iP, Thus, not all photomorphogenic processes reacted similarly in the lip1 mutant, but leaf expansion and plastid differentiation, including PLB formation, seemed to be regulated by the same signal transduction chain, Exogenously applied brassinolide could rescue neither dark- nor light-grown defects of the lip1 mutant. Thus, cytokinins but not brassinolides seem to be involved in the regulation of certain characteristic traits of skotomorphogenesis in pea, including plastid development and PLB formation.

  • 24.
    Sheng, Ming
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Hosseinzadeh, Ava
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Muralidharan, Somsundar Veppil
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Gaur, Rahul
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Tuck, Simon
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Aberrant Fat Metabolism in Caenorhabditis elegans Mutants with Defects in the Defecation Motor Program2015Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 4, artikel-id e0124515Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The molecular mechanisms by which dietary fatty acids are absorbed by the intestine, and the way in which the process is regulated are poorly understood. In a genetic screen for mutations affecting fat accumulation in the intestine of Caenorhabditis elegans, nematode worms, we have isolated mutations in the aex-5 gene, which encodes a Kex2/subtilisinfamily, Ca2+-sensitive proprotein convertase known to be required for maturation of certain neuropeptides, and for a discrete step in an ultradian rhythmic phenomenon called the defecation motor program. We demonstrate that aex-5 mutants have markedly lower steadystate levels of fat in the intestine, and that this defect is associated with a significant reduction in the rate at which labeled fatty acid derivatives are taken up from the intestinal lumen. Other mutations affecting the defecation motor program also affect steady-state levels of triglycerides, suggesting that the program is required per se for the proper accumulation of neutral lipids. Our results suggest that an important function of the defecation motor program in C. elegans is to promote the uptake of an important class of dietary nutrients. They also imply that modulation of the program might be one way in which worms adjust nutrient uptake in response to altered metabolic status.

  • 25. Skorzynska-Polit, E
    et al.
    Tukendorf, A
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Baszynski, T
    Calcium modifies Cd effect on runner bean plants1998Ingår i: Environmental and Experimental Botany, ISSN 0098-8472, E-ISSN 1873-7307, Vol. 40, nr 3, s. 275-286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of different Ca concentrations in the growth medium on the toxicity of 25 mu M CdSO4 was studied in runner bean plants (var. Piekny Jas) at two different growth stages of primary leaves. In young plants growing in a medium with low level of Ca a treatment with Cd for 12 days resulted in Ca accumulation in roots, a strong reduction of the leaf area, a decreased monogalactosyl diacylglycerol/digalactosyl diacylglycerol ratio and efficiency of the photosynthetic apparatus. In leaves of older plants growing under the same conditions, and surviving Cd treatment, a high accumulation of Ca but a low one of Cd, chlorosis of leaves, a decrease of the ratio monogalactosyl diacylglycerol/digalactosyl diacylglycerol and photosynthetic activity were shown. At a high level of Ca in the nutrient medium plant roots showed a remarkably high specificity to accumulate Cd but the toxic effect of the metal on plant growth parameters and content of pigments was decreased. No changes were observed in the level of galactolipids, but changes in fluorescence quenching were recorded. Calcium deficit enhanced the effect of Cd toxicity, including primary photochemistry, whereas excess Ca reduced toxic effects, while it is increasing the nonphotochemical quenching of excitation energy. (C) 1998 Elsevier Science B.V. All rights reserved.

  • 26. Szilágyi, Anna
    et al.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Åkerlund, Hans-Erik
    Laurdan fluorescence spectroscopy in the thylakoid bilayer: The effect of violaxanthin to zeaxanthin conversion on the galactolipid dominated lipid environment.2008Ingår i: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1778, nr 1, s. 348-355Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laurdan (6-lauroyl-2-dimethylaminonaphthalene) fluorescence spectroscopy has been applied to probe the physical status of the thylakoid membrane upon conversion of violaxanthin to zeaxanthin. So far, only phospholipid-dominated membranes have been studied by this method and hereby we report the first use of laurdan in mono- and digalactosyldiacylglycerol-dominated membrane systems. The generalised polarisation (GP) of laurdan was used as a measure of the structural effect of xanthophyll cycle pigments in isolated spinach (Spinacia oleracea) thylakoids and in model membrane vesicles composed of chloroplast galactolipids. Higher GP values indicate a membrane in a more ordered structure, whereas lower GP values point to a membrane in a less ordered fluid phase. The method was used to probe the effect of violaxanthin and zeaxanthin in thylakoid membranes at different temperatures. At 4, 25 and 37 °C the GP values for dark-adapted thylakoids in the violaxanthin-form were 0.55, 0.28 and 0.26. After conversion of violaxanthin to zeaxanthin, at the same temperatures, the GP values were 0.62, 0.36 and 0.34, respectively. GP values increased gradually upon conversion of violaxanthin to zeaxanthin. Similar results were obtained in the liposomal systems in the presence of these xanthophyll cycle pigments. We conclude from these results that the conversion of violaxanthin to zeaxanthin makes the thylakoid membrane more ordered.

  • 27. THORE, M
    et al.
    LOFGREN, S
    TARNVIK, A
    MONSEN, T
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    BURMAN, LG
    ANAEROBIC PHAGOCYTOSIS, KILLING, AND DEGRADATION OF STREPTOCOCCUS-PNEUMONIAE BY HUMAN PERIPHERAL-BLOOD LEUKOCYTES1985Ingår i: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 47, nr 1, s. 277-281Artikel i tidskrift (Refereegranskat)
  • 28. WIDELLWIGGE, A
    et al.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    EFFECTS OF SALT WASH ON THE STRUCTURE OF THE PROLAMELLAR BODY MEMBRANE AND THE MEMBRANE-BINDING OF NADPH-PROTOCHLOROPHYLLIDE OXIDOREDUCTASE1990Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 78, nr 3, s. 315-323Artikel i tidskrift (Refereegranskat)
  • 29. WIESLANDER, A
    et al.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ACYL-CHAIN-DEPENDENT INCORPORATION OF CHLOROPHYLL AND CHOLESTEROL IN MEMBRANES OF ACHOLEPLASMA-LAIDLAWII1987Ingår i: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 901, nr 2, s. 250-254Artikel i tidskrift (Refereegranskat)
  • 30. Williams, W P
    et al.
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Brain, T
    X-ray diffraction studies of the structural organisation of prolamellar bodies isolated from Zea mays1998Ingår i: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 422, nr 2, s. 252-254Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transmission electron microscopy (TEM) indicates that maize prolamellar bodies (PLBs) are built up of tetrapodal units based on a highly convoluted but continuous lipid bilayer exhibiting diamond cubic (Fd3m) symmetry. Such lattices are often described in terms of infinite periodic minimal surfaces (IMPS) exhibiting zero net curvature and dividing the system into two identical subvolumes. IT so, X-ray diffraction measurements would bt: expected ci to index ore a double-diamond (Pn3m) lattice with a unit cell length half that of the TEM lattice. Our measurements index on a Fd3m lattice with a similar repeat distance to thr TEM images. The PLB membrane is thus inherently asymmetric, probably as the result of the distribution of membrane protein. (C) 1998 Federation of European Biochemical Societies.

  • 31. WINGSLE, G
    et al.
    MATTSON, A
    EKBLAD, A
    HALLGREN, JE
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ACTIVITIES OF GLUTATHIONE-REDUCTASE AND SUPEROXIDE-DISMUTASE IN RELATION TO CHANGES OF LIPIDS AND PIGMENTS DUE TO OZONE IN SEEDLINGS OF PINUS-SYLVESTRIS (L)1992Ingår i: Plant Science, ISSN 0168-9452, E-ISSN 1873-2259, Vol. 82, nr 2, s. 167-178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scots pine seedlings (Pinus sylvestris L.) were exposed to ozone at a high-level, 300 ppb 8 h/day for 5 days, and at a low-level, 70-80 ppb 8 h/day for 10 days. In the high-level and low-level experiment the chlorophyll a content decreased 11% and 8%, respectively. The high-level ozone experiment affected the xanthophyll cycle by a 19% higher level of violaxanthin in the exposed seedlings compared to controls at day 5. This was also accompanied by a 42% lower concentration of zeaxanthin. No significant changes of the carotenoids neoxanthin, lutein, alpha-carotene or beta-carotene were found. The molar ratio monogalactosyl diacylglycerol/digalactosyl diacylglycerol decreased by 11% in the high-level ozone exposure. This suggests that the galactolipid:galactolipid galactosyl transferase, located in the outer envelope membrane of the chloroplast, was stimulated by ozone. No significant changes in the total membrane lipid or the acyl group composition was detected. In the high-level ozone experiment the concentration of soluble protein increased in the exposed seedlings during the last 3 days of the experimental period without any change in total protein. No visible damages were observed. The results showed that the activity of the defence enzymes superoxide dismutase (EC 1.15.1.1) and glutathione reductase (EC 1.6.4.2) was not altered after ozone exposure.

  • 32. Zhang, Lifang
    et al.
    Selao, Tiago Toscano
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Norling, Birgitta
    Subcellular Localization of Carotenoid Biosynthesis in Synechocystis sp PCC 68032015Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 6, artikel-id e0130904Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The biosynthesis pathway of carotenoids in cyanobacteria is partly described. However, the subcellular localization of individual steps is so far unknown. Carotenoid analysis of different membrane subfractions in Synechocystis sp. PCC6803 shows that "light" plasma membranes have a high carotenoid/protein ratio, when compared to "heavier" plasma membranes or thylakoids. The localization of CrtQ and CrtO, two well-defined carotenoid synthesis pathway enzymes in Synechocystis, was studied by epitope tagging and western blots. Both enzymes are locally more abundant in plasma membranes than in thylakoids, implying that the plasma membrane has higher synthesis rates of beta-carotene precursor molecules and echinenone.

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