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  • 151.
    Meining, Winfried
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Eberhardt, S
    Bacher, A
    Ladenstein, R
    Crystallization and preliminary crystallographic analysis of the recombinant N-terminal domain of riboflavin synthase2001Inngår i: Acta Crystallographica Section D: Biological Crystallography, ISSN 0907-4449, E-ISSN 1399-0047, Vol. 57, s. 1296-1299Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Riboflavin synthase catalyzes the final step in the biosynthesis of riboflavin. Animals and humans lack this enzyme, whereas many bacteria and certain yeasts are absolutely dependent on endogenous riboflavin synthesis. Riboflavin synthase is therefore an attractive target for chemotherapy. The N-terminal domain of riboflavin synthase forms a dimer in solution and is capable of strongly binding riboflavin. It can serve as a model for the binding site of the native enzyme. Structural information obtained from this domain at high resolution will be helpful in the determination of the binding mode of riboflavin and thus for the development of antimicrobial drugs. Here, the crystallization and preliminary crystallographic analysis of the N-terminal domain of riboflavin synthase are reported. The crystals belong to the space group C222(1), with unit-cell parameters a = 50.3, b = 104.7, c = 85.3 Angstrom, alpha = beta = gamma = 90 degrees, and diffract to 2.6 Angstrom resolution.

  • 152.
    Meining, Winfried
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Eberhardt, S
    Bacher, A
    Ladenstein, R
    The structure of the N-terminal domain of riboflavin synthase in complex with riboflavin at 2.6 A resolution2003Inngår i: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 331, nr 5, s. 1053-1063Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Riboflavin synthase of Escherichia coli is a homotrimer with a molecular mass of 70 kDa. The enzyme catalyzes the dismutation of 6,7-dimethyl-8(1'-D-ribityl)-lumazine, affording riboflavin and 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione. The N-terminal segment (residues 1-87) and the C-terminal segment (residues 98-187) form beta-barrels with similar fold and a high degree of sequence similarity. A recombinant peptide comprising amino acid residues 1-97 forms a dimer, which binds riboflavin with high affinity. Here,we report the structure of this construct in complex with riboflavin at 2.6 Angstrom resolution. It is demonstrated that the complex can serve as a model for ligand-binding in the native enzyme. The structure and riboflavin-binding mode is in excellent agreement with structural information obtained from the native enzyme from Escherichia coli and riboflavin synthase from Schizosaccharomyces pombe. The implications for the binding specificity and the regiospecificity of the catalyzed reaction are discussed.

  • 153.
    Meining, Winfried
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Intitute.
    Mortl, S
    Fischer, M
    Cushman, M
    Bacher, A
    Ladenstein, R
    The atomic structure of pentameric lumazine synthase from Saccharomyces cerevisiae at 1.85 angstrom resolution reveals the binding mode of a phosphonate intermediate analogue2000Inngår i: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 299, nr 1, s. 181-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lumazine synthase of Saccharomyces cerevisiae is a homopentamer with a molecular weight of 90 kDa. Crystals of the recombinant enzyme with a size of up to 1.6 mm were obtained. The space group is P4(1)2(1)2 with lattice dimensions 82.9 Angstrom * 82.9 Angstrom * 300.2 Angstrom. X-ray diffraction data collected under cryogenic conditions were complete to 1.85 Angstrom resolution. The structure of the enzyme in complex with the intermediate analogue, 5-(6-D-ribitylamino-2,4-dihydroxypyrimidine-5-yl)-1-pentyl-phosphonic acid was solved via molecular replacement using the structure of the Bacillus subtilis enzyme as search model and was refined to a final X-factor of 19.8% (R-free:22.5%). The conformation of the active site ligand of the enzyme mimicks that of the Schiff base intermediate of the enzyme-catalyzed reaction. The data enable the reconstruction of the reactant topology during the early steps of the catalytic reaction. Structural determinants, which are likely to be responsible for the inability of the S. cerevisiae enzyme to form icosahedral capsids, will be discussed.

  • 154.
    Miranda-Vizuete, A
    et al.
    Karolinska Institute.
    Spyrou, Giannis
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Genomic organization and identification of a novel alternative splicing variant of mouse mitochondrial thioredoxin reductase (TrxR2) gene2002Inngår i: Molecules and Cells, ISSN 1016-8478, E-ISSN 0219-1032, Vol. 13, nr 3, s. 488-492Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eukaryotic mitochondria are equipped with a complete thioredoxin system, composed of thioredoxin and thioredoxin reductase, which has been implicated in the protection against the reactive oxygen intermediates generated during the respiratory process in this organelle. Like its cytosolic counterpart, mammalian mitochondrial thioredoxin reductase is a homodimeric selenoprotein. We report here the genomic organization of the mouse mitochondrial thioredoxin gene (TrxR2) that spans 53 kb and consists of 18 exons ranging from 20 to 210 bp. All splicing sites conformed to the GT/AG rule with the exon-intron boundaries located exactly at the same position as the human TrxR2 gene, the only mammalian mitochondrial thioredoxin reductase gene whose genomic structure has been elucidated to date. In addition, we have identified a novel mRNA splicing variant lacking intron 14 resulting in a protein subunit with a shorter interface domain This new splicing variant provides a frame work for further analysis of this important enzyme as its predicted homodimeric conformation can now be expanded to a putative heterodimeric structure as well as a small subunit homodimer with the obvious implications at the regulatory level.

  • 155. Moore, A
    et al.
    Olsén, K Håkan
    Södertörns högskola, Avdelning Naturvetenskap.
    Lower, N
    Kindahl, Hans
    The role of F-series prostaglandins as reproductive priming pheromones in the brown trout2002Inngår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 60, nr 3, s. 613-624Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrophysiological studies demonstrated that the olfactory epithelium of mature male brown trout Salmo trutta parr was acutely sensitive to F-series prostaglandins (PGFS) PGF(1alpha) and PGF(2alpha), with detection threshold concentrations of 10(-11) M. The olfactory epithelium was also sensitive to the PGF metabolite 15-ketoPGF(2alpha) (threshold 10(-8) M), but did not detect a further metabolite, 13,14,-dihydro-15-ketoPGF(2alpha). Immature brown trout did not detect any of the prostaglandins tested. Exposure of mature male brown trout parr to waterborne PGF(1alpha) and PGF(2alpha) (concentration 10(-8) M). resulted in significant increases in levels of expressible milt and the plasma concentrations of 17,20-betadihydroxy-4-pregnen-3-one, testosterone and 11-ketotestosterone. The olfactory epithelium of both immature and mature male brown trout parr was sensitive to the urine and ovarian fluid from ovulated female brown trout. Exposure of mature male brown trout parr to ovarian fluid resulted in an increase in the levels of plasma 17,20beta-dihydroxy-4-pregnen-3-one whilst exposure to urine increased the levels of expressible milt. In addition, PGF(2alpha) was found to be present within both the urine and ovarian fluid of mature female brown trout. It is suggested that the F-series prostaglandins have a role as priming pheromones in male brown trout.

  • 156.
    Månsson, Martin
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    The structural diversity of lipopolysaccharides expressed by genetically defined clinical isolates of nontypeable Haemophilus influenzae2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Nontypeable Haemophilus influenzae (NTHi) is an important cause of otitis media and respiratory tract infections. Its lipopolysaccharide (LPS) molecule, an outer membrane component, is a major virulence factor of NTHi. The LPS molecule may also be an efficient target for antibodies which might be protective against NTHi disease. The present thesis describes the structural analyses of the LPS from a number of NTHi clinical isolates. These isolates have been selected to be representative of the genetic diversity in the natural population of NTHi. The studies revealed extended inter- and intrastrain variability in LPS expression but also the presence of a conserved structural element. Several novel structural features were found, including epitopes not previously observed in Haemophilus influenzae LPS. The studies were performed using nuclear magnetic resonance spectroscopy, electrospray ionization mass spectrometry and different chemical degradations of the LPS as the principal methods.

  • 157.
    Månsson, Martin
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Bauer, Sebastian H J
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Hood, D W
    John Radcliffe Hospital, Headington, Oxford, UK.
    Richards, J C
    National Research Council of Canada, Ottawa, Ontario, Canada.
    Moxon, E R
    National Research Council of Canada, Ottawa, Ontario, Canada.
    Schweda, Elke K H
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    A new structural type for Haemophilus influenzae lipopolysaccharide: Structural analysis of the lipopolysaccharide from nontypeable Haemophilus influenzae strain 4862001Inngår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 268, nr 7, s. 2148-2159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Structural elucidation of the sialylated lipopolysaccharide (LPS) of non-typeable Haemophilus influenzae (NTHi) strain 486 has been achieved by the application of high-field NMR techniques and ESI-MS along with composition and linkage analyses on O-deacylated LPS and oligosaccharide samples. It was found that the LPS contains the common element of H. influenzae, L-alpha -D-Hepp-(1-->2)][PEtn-->6]-L-alpha -D-Hepp-(1-->3)-[beta -D-Glcp-( 1-->4)]-L-alpha -D-Hepp-(1-->5)- [PPEtn-->4]-alpha -Kdop- (2-->6)-Lipid A, but instead of glycosyl substitution of the terminal heptose residue (HepIII) at the O2 position observed in other H. influenzae strains, HepIII is chain elongated at the O3 position by either lactose or sialyllactose (i.e. alpha -Neu5Ac(2-->3)-beta -D-Galp-(1-->4)-beta -D-Glcp). The LPS is substituted by an O-acetyl group linked to the O2 position of HepIII and phosphocholine (PCho) which was located at the O6 position of a terminal alpha -D-Glcp, residue attached to the central heptose, a molecular environment different from what has been reported earlier for PCho. In addition, minor substitution by O-linked glycine to the LPS was observed. By investigation of LPS from a lpsA mutant of NTHi strain 486, it was demonstrated that the lpsA gene product also is responsible for chain extension from HepIII in this strain. The involvement of lic1 in expression of PCho was established by investigation of a lic1 mutant of NTHi strain 486.

  • 158.
    Månsson, Martin
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Hood, D W
    John Radcliffe Hospital, Oxford, UK.
    Li, J J
    National Research Council of Canada, Ottawa, Ontario, Canada.
    Richards, J C
    National Research Council of Canada, Ottawa, Ontario, Canada.
    Moxon, E R
    John Radcliffe Hospital, Oxford, UK.
    Schweda, Elke K H
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Structural analysis of the lipopolysaccharide from nontypeable Haemophilus influenzae strain 10032002Inngår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 269, nr 3, s. 808-818Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Structural analysis of the lipopolysaccharide (LPS) of nontypeable Haemophilus influenzae strain 1003 has been achieved by the application of high-field NMR techniques, ESI-MS. capillary electrophoresis coupled to ESI-MS. composition and linkage analyses on O-deacylated LPS and core oligosaccharide material. It was found that the LPS contains the common structural element of H. influenzae, L-alpha-D-Hepp-(1 --> 2)-[PEtn --> 6]-L-alpha-D-Hepp-(1 --> 3)-[beta-D-Glcp-(1 --> 4)]-L-alpha-D-Hepp-(1 --> 5)-[PP Etn --> 4]-alpha-Kdop-(2 --> 6)-Lipid A. in which the beta-D-Glcp residue is substituted by phosphocholine at O-6 and an acetyl group at O-4. A second acetyl group is located at O-3 of the distal heptose residue (HepIII). HepIII is chain elongated at O-2 by either a beta-D-Glcp residue (major), lactose or sialyllactose (minor, i.e. alpha-Neu5Ac-(2 --> 3)-beta-D-Galp-(1 --> 4)-beta-D-Glcp), where a third minor acetylation site was identified at the glucose residue. Disialylated species were also detected. In addition. a minor substitution of ester-linked glycine at HepIII and Kdo was observed.

  • 159.
    Månsson, Martin
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Hood, D W
    John Radcliffe Hospital, Oxford, UK.
    Moxon, E R
    John Radcliffe Hospital, Oxford, UK.
    Schweda, Elke K H
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Structural characterization of a novel branching pattern in the lipopolysaccharide from nontypeable Haemophilus influenzae2003Inngår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 270, nr 14, s. 2979-2991Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Structural analysis of the lipopolysaccharide (LPS) from nontypeable Haemophilus influenzae strain 981 has been achieved using NMR spectroscopy and ESI-MS on O-deacylated LPS and core oligosaccharide (OS) material as well as by ESI-MSn on permethylated dephosphorylated OS. A heterogeneous glycoform population was identified, resulting from the variable length of the OS branches attached to the glucose residue in the common structural element of H. influenzae LPS, L-alpha-d-Hepp -(1-->2)-[P Etn-->6]-L-alpha-d-Hepp -(1-->3)-[beta-d-Glcxp-(1-->4)]-L-alpha-d-Hepp -(1-->5)-[PP Etn-->4]-alpha-Kdop -(2-->6)-Lipid A. Notably, the O-6 position of the beta-d-Glcp residue was either substituted by P Cho or the disaccharide branch beta-d-Galp-(1-->4)-d-alpha-d-Hepp, while the O-4 position was substituted by the globotetraose unit, beta-d-Galp NAc-(1-->3)-alpha-d-Galp -(1-->4)-beta-d-Galp -(1-->4)-beta-d-Glcp, or sequentially truncated versions thereof. This is the first time a branching sugar residue has been reported in the outer-core region of H. influenzae LPS. Additionally, a P Etn group was identified at O-3 of the distal heptose residue in the inner-core.

  • 160.
    Månsson, Martin
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Hood, D W
    John Radcliffe Hospital, Oxford, UK.
    Moxon, E R
    John Radcliffe Hospital, Oxford, UK.
    Schweda, Elke K H
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Structural diversity in lipopolysaccharide expression in nontypeable Haemophilus influenzae - Identification of L-glycero-D-manno-heptose in the outer-core region in three clinical isolates2003Inngår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 270, nr 4, s. 610-624Artikkel i tidsskrift (Fagfellevurdert)
  • 161.
    Neely, K E
    et al.
    Pennsylvania State University, Pennsylvania, USA.
    Hassan, A H
    Pennsylvania State University, Pennsylvania, USA.
    Wallberg, Annika E
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Steger, D J
    Pennsylvania State University, Pennsylvania, USA.
    Cairns, B R
    University of Utah School of Medicine, Salt Lake City, USA.
    Wright, Athony P H
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Workman, J L
    Pennsylvania State University, Pennsylvania, USA.
    Activation domain-mediated targeting of the SWI/SNF complex to promoters stimulates transcription from nucleosome arrays1999Inngår i: Molecular Cell, ISSN 1097-2765, E-ISSN 1097-4164, Vol. 4, nr 4, s. 649-655Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The yeast SWI/SNF complex is required for the transcription of several yeast genes and has been shown to alter nucleosome structure in an ATP-dependent reaction. In this study, we show that the complex stimulated in vitro transcription from nucleosome templates in an activation domain-dependent manner. Transcription stimulation by SWI/SNF required an activation domain with which it directly interacts. The acidic activation domains of VP16, Gcn4, Swi5, and Hap4 interacted directly with the purified SWI/SNF complex and with the SWI/SNF complex in whole-cell extracts. The similarity of activation domain interactions and transcriptional stimulation between SWI/SNF and the SAGA histone acetyltransferase complex may account for their apparent overlapping functions in vivo.

  • 162. Nikus, J
    et al.
    Esen, A
    Jonsson, Lisbeth M V
    Södertörns högskola, Avdelning Naturvetenskap.
    Cloning of a plastidic rye (Secale cereale) beta-glucosidase cDNA and its expression in Escherichia coli2003Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 118, nr 3, s. 337-345Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The cDNA for a beta-glucosidase (EC3.2.1.21) was isolated from rye (Secale cereale, cv Motto) and the sequence corresponding to the mature protein cloned into pET21a expression vector and used for transformation of Escherichia coli. The recombinant beta-glucosidase expressed in E. coli was recognized by antibodies to maize beta-glucosidase and exhibited the same kinetic properties on the endogenous substrates hydroxamic acid glucosides and artificial substrates as the native enzyme purified from rye. The enzyme monomer had an apparent molecular weight of about 67 kDa. The isolated cDNA was analysed with web-based chloroplast targeting prediction programs. The programs predicted a chloroplast targeting peptide with a cleavage site between amino acid 49 and 50. Sequence alignment of the plastidic rye beta-glucosidase showed that the putative sites for substrate specificity of maize Glu1, W378 and F198 (F197) are conserved in the rye enzyme, whereas F205, F466 and A467 of maize Glu1 are exchanged for histidine, glycine and serine, respectively, in rye. The plastidic beta-glucosidase is expressed in all plant parts and the highest levels were found in the coleoptile and mesocotyl.

  • 163. Nordling, M M
    et al.
    Nygren, Jonas
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Sundberg, K
    Rafter, J J
    Toxicological characterization of a novel in vivo benzo[a]lpyrene metabolite, 7-oxo-benz[d]anthracene-3,4-dicarboxylic acid anhydride2002Inngår i: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 15, nr 10, s. 1274-1280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, we described a new in vivo pathway in the metabolism of benzo[a]pyrene (BP) that involves an opening of the aromatic ring system. One of the products of this pathway, isolated from rat urine, was the anhydride of 7-oxo-benz[d]anthracene-3,4-dicarboxylic acid (ABADA). We have now investigated the effect of ABADA on several cellular targets, known to be important in tumor formation. ABADA was as efficient as BP-7,8-diol-9,10-epoxide in inducing direct strand breaks but not alkali labile sites in DNA in HT-29 cells and exhibited weak mutagenic activity in Salmonella typhimurium strain TA 102. The cytotoxicity of ABADA to HCT 116 cells appeared to be due to apoptosis, as caspase-3 activity and poly-ADP-ribose polymerase (PARP) cleavage was observed. COX-2 promoter activity was induced by ABADA in HCT 116 cells. In conclusion, this novel metabolic pathway may also be contributing to the carcinogenicity of BP.

  • 164. Nordstrand, K
    et al.
    Sandstrom, A
    Aslund, F
    Holmgren, A
    Otting, G
    Berndt, Kurt D
    Södertörns högskola, Avdelning Naturvetenskap.
    NMR structure of oxidized glutaredoxin 3 from Escherichia coli2000Inngår i: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 303, nr 3, s. 423-432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A high precision NMR structure of oxidized glutaredoxin 3 [C65Y] from Escherichia coli has been determined. The conformation of the active site including the disulphide bridge is highly similar to those in glutaredoxins from pig liver and T4 phage. A comparison with the previously determined structure of glutaredoxin 3 [C14S, C65Y] in a complex with glutathione reveals conformational changes between the free and substrate-bound form which includes the sidechain of the conserved, active site tyrosine residue. In the oxidized form this tyrosine is solvent exposed, while it adopts less exposed conformation, stabilized by hydrogen bonds, in the mixed disulfide with glutathione. The structures further suggest that the formation of a covalent linkage between glutathione and glutaredoxin 3 is necessary in order to induce these structural changes upon binding of the glutathione peptide. This could explain the observed low affinity of glutaredoxins for S-blocked glutathione analogues, in spite of the fact that glutaredoxins are highly specific reductants of glutathione mixed disulfides.

  • 165. Oh, H
    et al.
    Edlund, Charlotta
    Södertörns högskola, Avdelning Naturvetenskap.
    Mechanism of quinolone resistance in anaerobic bacteria2003Inngår i: Clinical Microbiology and Infection, ISSN 1198-743X, E-ISSN 1469-0691, Vol. 9, nr 6, s. 512-517Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several recently developed quinolones have excellent activity against a broad range of aerobic and anaerobic bacteria and are thus potential drugs for the treatment of serious anaerobic and mixed infections. Resistance to quinolones is increasing worldwide, but is still relatively infrequent among anaerobes. Two main mechanisms, alteration of target enzymes (gyrase and topoisomerase IV) caused by chromosomal mutations in encoding genes, or reduced intracellular accumulation due to increased efflux of the drug, are associated with quinolone resistance. These mechanisms have also been found in anaerobic species. High-level resistance to the newer broad-spectrum quinolones often requires stepwise mutations in target genes. The increasing emergence of resistance among anaerobes may be a consequence of previous widespread use of quinolones, which may have enriched first-step mutants in the intestinal tract. Quinolone resistance in the Bacteroides fragilis group strains is strongly correlated with amino acid substitutions at positions 82 and 86 in GyrA (equivalent to positions 83 and 87 of Escherichia coli ). Several studies have indicated that B. fragilis group strains possess efflux pump systems that actively expel quinolones, leading to resistance. DNA gyrase seems also to be the primary target for quinolones in Clostridium difficile , since amino acid substitutions in GyrA and GyrB have been detected in resistant strains. To what extent other mechanisms, such as mutational events in other target genes or alterations in outer-membrane proteins, contribute to resistance among anaerobes needs to be further investigated.

  • 166. Oh, H
    et al.
    El Amin, N
    Davies, T
    Appelbaum, P C
    Edlund, Charlotta
    Södertörns högskola, Avdelning Naturvetenskap.
    gyrA Mutations associated with quinolone resistance in Bacteroides fragilis group strains2001Inngår i: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 45, nr 7, s. 1977-1981Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mutations in the gyrA gene contribute considerably to quinolone resistance in Escherichia coli. Mechanisms for quinolone resistance in anaerobic bacteria are less well studied. The Bacteroides fragilis group are the anaerobic organisms most frequently isolated from patients with bacteremia and intraabdominal infections. Forty-four clinafloxacin-resistant and-susceptible fecal and clinical isolates of the B. fragilis group (eight Bacteroides fragilis, three Bacteroides ovatus, five Bacteroides thetaiotaomicron, six Bacteroides uniformis, and 22 Bacteroides vulgatus) and six ATCC strains of the B. fragilis group were analyzed as follows: (i) determination of susceptibility to ciprofloxacin, levofloxacin, moxifloxacin, and clinafloxacin by the agar dilution method and (ii) sequencing of the gyrA quinolone resistance-determining region (QRDR) located between amino acid residues equivalent to Ala-67 through Gln-106 in E. coli. Amino acid substitutions were found at hotspots at positions 82 (n = 15) and 86 (n = 8). Strains with Ser82Leu substitutions (n = 13) were highly resistant to all quinolones tested. Mutations in other positions of gyrA were also frequently found in quinolone-resistant and -susceptible isolates. Eight clinical strains that lacked mutations in their QRDR were susceptible to at least two of the quinolones tested. Although newer quinolones have good antimicrobial activity against the B. fragilis group, quinolone resistance in B. fragilis strains can be readily selected in vivo. Mutational events in the QRDR of gyrA seem to contribute to quinolone resistance in Bacteroides species.

  • 167. Oh, H
    et al.
    Hedberg, M
    Wade, D
    Edlund, Charlotta
    Södertörns högskola, Avdelning Naturvetenskap.
    Activities of synthetic hybrid peptides against anaerobic bacteria: Aspects of methodology and stability2000Inngår i: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 44, nr 1, s. 68-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The increasing problem of antibiotic resistance among pathogenic bacteria requires development of new antimicrobial agents. One line of investigation is the synthesis of antimicrobial hybrid peptides, The aim of the present investigation was to determine the in vitro activities of 16 cecropin-melittin hybrid peptides (CAMEL analogues) against 60 anaerobic bacterial strains, to compare their activities with those of seven clinically used antimicrobial agents, and to compare different methods for anaerobic susceptibility testing of these peptides. The stability of one of the peptides, temporin B, with different stereoisomeric configurations was investigated in a fecal milieu. The CAMEL analogues showed antimicrobial activity against the anaerobic bacteria, with MICs ranging from 0.125 to 32 mu g/ml. The overall activities (the MICs at which 90% of isolates are inhibited) of the CAR IEL analogues against anaerobic bacteria were mainly inferior to those of imipenem, clindamycin, and piperacillin but were equal to or superior to those of metronidazole, cefoxitin, ciprofloxacin, and chloramphenicol. The agarose dilution method was found to be an accurate method for the testing of large numbers of bacterial strains. The D isomer of temporin B was inactivated more slowly in feces than the L isomer. This study shows that the CAMEL analogues are potential agents for the treatment of anaerobic infections.

  • 168. Oh, H
    et al.
    Nord, C E
    Barkholt, L
    Hedberg, M
    Edlund, Charlotta
    Södertörns högskola, Avdelning Naturvetenskap.
    Ecological disturbances in intestinal microflora caused by clinafloxacin, an extended-spectrum quinolone2000Inngår i: Infection. Zeitschrift für Klinik und Therapie der Infektionen, ISSN 0300-8126, E-ISSN 1439-0973, Vol. 28, nr 5, s. 272-277Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: The quinolones developed over the past few years have enhanced in vitro activity and a broader spectrum of antimicrobial activity compared to ma ny other antimicrobial agents including the older quinolones. The present study focuses on the effect of clinafloxacin, a member of the new broad-spectrum quinolone class of antibiotics, on the normal intestinal microflora. Subjects and Methods: A total of it healthy volunteers received clinafloxacin orally, zoo mg twice daily for 7 days. Fecal specimens were collected at defined intervals before, during and after the administration in order to study the effect of clinafloxacin on the intestinal microflora and to correlate this effect with fecal clinafloxacin concentrations. Intestinal microorganisms isolated before, during and 2 weeks after clinafloxacin administration were tested for their suseptibility to clinafloxacin. Results: Oral administration of clinafloxacin resulted in high drug levels in feces (mean value 176.2 mg/kg on day 7) and pronounced ecological disturbances. The aerobic microflora was eradicated in 11 of the 12 subjects and the anaerobic microflora was strongly suppressed during administration. There was a significant emergence of clinafloxacin-resistant Bacteroides spp, strains (MIC greater than or equal to 4 mg/ml) during administration. The elevated MIC values still remained 2 weeks after discontinuation of the antibiotic (p < 0.001). Conclusion: The emergence of clinafloxacin-resistant Bacteroides spp. demonstrates the necessity of restricting prescription for particular indications in order to preserve the efficacy of the highly active broad-spectrum quinolones.

  • 169.
    Oh, Herin
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Hedberg, M
    Karolinska Institutet.
    Edlund, Charlotta
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Efflux-mediated fluoroquinolone resistance in the Bacteroides fragilis group2002Inngår i: Anaerobe, ISSN 1075-9964, E-ISSN 1095-8274, Vol. 8, nr 5, s. 277-282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to investigate the role of efflux pumps in fluoroquinolone resistance, 35 Bacteroides fragilis group isolates with various resistance patterns against ciprofloxacin, levofloxacin, moxifloxacin and clinafloxacin were studied. The gyrA genotypes were known in all isolates studied. The accumulation of ciprofloxacin with and without carbonyl cyanide m-chlorophenylhydrazone (CCCP) was investigated using a silicon oil based fluorometric assay. Seventeen of 25 multiquinolone-resistant strains had significantly increased ciprofloxacin accumulation in the presence of CCCP compared to the corresponding susceptible type strains. Ten of the resistant isolates with increased efflux had no target mutations at positions 82 or 86 of their GyrA subunits. Strains with highly enhanced efflux were consequently shown to have a significant decrease of quinolone MIC values in the presence of efflux pump inhibitor. The results of the present study propose that high levels of resistance to older as well as newer fluoroquinolones, could be explained by increased activity of efflux pumps in B. fragilis group strains.

  • 170.
    Ohlson, Lena C. E.
    et al.
    Karolinska Institutet.
    Koroxenidou, Lena
    Södertörns högskola, Avdelning Naturvetenskap, Biologi.
    Porsch Hällström, Inger
    Karolinska Institutet.
    Inhibition of in vivo rat liver regeneration by 2-acetylaminofluorene affects the regulation of cell cycle-related proteins1998Inngår i: Hepatology, ISSN 0270-9139, E-ISSN 1527-3350, Vol. 27, nr 3, s. 691-696Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of dietary 2-acetylaminofluorene (2-AAF) on cell cycle-related proteins was studied in regenerating livers from male Wistar rats, The levels of cyclins, cyclin dependent kinases (cdks), and related proteins were studied at different times during the first cell cycle after partial hepatectomy (PH). The frequency of proliferation cell nuclear antigen (PCNA)-positive nuclei, a marker of S phase progression, was almost zero during the first 27 hours after PH in the mitoinhibited 2-AAF-treated rats, while about 50% of the nuclei were labeled 24 hours after PH in control animals. Accordingly, Western blot tests showed markedly elevated PCNA protein levels from 18 hours to the end of S phase in untreated animals but no upregulation in response to 2-AAF. Compared with control animals, animals treated with 2-AAF showed increased levels of cdk 4 and cyclin D-3 from 12 and 15 hours after PH, respectively, and altered cyclicity in cyclin Dg expression. No effects on cyclin E were observed, while the increase in cdk 2 levels in control animals during late G(1)/S (15-27 hours) was abolished by 2-AAF. p53 was induced by 2-AAF treatment during the same period, with a peak at 24 hours. The protein detected with p21 antibodies was highly expressed in unstimulated hepatocytes in control animals, and further increased by 2-AAF. The expression was sustained until 15 hours after PH in control rats while 2-AAF-treated animals lacked detectable protein during this period; however, a transient increase was observed at 21 hours, Thus, 2-AAF affects several parameters of cell cycle regulation of possible relevance for its inhibitory effects on hepatocyte proliferation in vivo.

  • 171. Okorokova-Facanha, A L
    et al.
    Okorokov, L A
    Ekwall, Karl
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    An inventory of the P-type ATPases in the fission yeast Schizosaccharomyces pombe2003Inngår i: Current Genetics, ISSN 0172-8083, E-ISSN 1432-0983, Vol. 43, nr 4, s. 273-280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The analysis of the Schizosaccharomyces pombe genome revealed the presence of 14 putative P-type ATPases. The clustering of ATPases resembles that of Saccharomyces cerevisiae, indicating that the main classes of pumps were already present before the split of the Archiascomycetes from the other Ascomycota. The overall amino acid identity between fission and budding yeast P-type ATPases is generally low (30-50%). This is similar to the fungus-plant and fungus-animal comparisons.. suggesting that fungal ATPases underwent an extensive process of diversification. Unlike Sac. cerevisiae. fission yeast lacks Na+-ATPases, has a single heavy-metal ATPase and three ATPases of unknown specificity. The observed divergence within these fungi might reflect physiological differences, including adaptation to environmental stresses.

  • 172.
    Olsen, K Håkan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Grahn, Mats
    Södertörns högskola, Avdelning Naturvetenskap.
    Lohm, Jakob
    Influence of MHC on sibling discrimination in Arctic char, Salvelinus alpinus (L.)2002Inngår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 28, nr 4, s. 783-795Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The preference of juvenile Arctic char [Salvelinus alpinus (L.)] for odors from siblings and nonsiblings with different major histocompability complex class II (MHC) genotypes was studied in two-choice fluviarium tests. In the first part of the study, test fish demonstrated no preference for water scented by a sibling with a MHC genotype different from its own versus water scented by a MHC identical nonsibling. When both donors were siblings with different MHC genotypes, however, the test fish chose the water scented by the fish with the same MHC type as the test fish. The results suggest that odors with information about kinship are dependent on MHC but also on other, unknown factors. In the second part of the study, we observed that fish isolated since fertilization did not show any behavioral discrimination towards siblings, based on MHC genotype. One reasonable explanation for this result is that Arctic char learn to discriminate between odors from individuals of different MHC types.

  • 173.
    Olsen, K Håkan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Grahn, Mats
    Södertörns högskola, Avdelning Naturvetenskap.
    Lohm, Jakob
    The influence of dominance and diet on individual odours in MHC identical juvenile Arctic charr siblings2003Inngår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 63, nr 4, s. 855-862Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    No difference in attraction was observed in sibling Artic charr Salvelinus alpinus between water scented by dominant or subordinate major histocompability complex (MHC) identical fish observed in a two-choice fluviarium. In a second experiment, MHC identical sibling donors were given different types of food pellets before the preference test. The test fish showed a significant attraction to the sibling given the same kind of food as the test fish itself during the first 6 h of the fluviarium tests. The results suggest that diet has an influence on the odours released and can, in addition to MHC related odours, be used for information relating to group member identity.

  • 174.
    Olsén, K Håkan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Bjerselius, Rickard
    Mayer, Ian
    Kindahl, Hans
    Both ovarian fluid and female urine increase sex steroid hormone levels in mature Atlantic salmon (Salmo salar) male parr2001Inngår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 27, nr 11, s. 2337-2349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We compared the ability of urine and ovarian fluid from female Atlantic salmon (Salmo salar) to stimulate increase in plasma concentrations of sex steroid hormones in mature conspecific male parr (priming effect of the stimuli). We also tested the hypothesis that prostaglandin F-2 alpha (PGF(2 alpha)) may act as a priming pheromone in the tested stimulants. Individual males of salmon parr were exposed to female urine, ovarian fluid, urine-ovarian fluid mix, or PGF(2 alpha) Plasma concentrations of the sex steroids of 17,20 beta -dihydroxy-4-pregnen-3-one (17,20 beta -P) were higher in males exposed to urine, ovarian fluids, and PGF(2 alpha), compared to control males. PGF(2 alpha). and a mixture of urine and ovarian fluid also gave increased concentrations of 11-ketotestosterone (11-KT). Concentrations of PGF(2 alpha) were higher in ovarian fluids than in urine. A behavior test with mature male part in a fluviarium showed neither attraction to nor avoidance of 0.1 nM PGF(2 alpha), but plasma levels of 17,20 beta -P were significantly higher in exposed males compared to controls.

  • 175.
    Olsén, K Håkan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Johansson, Anna-Karin
    Bjerselius, Rickard
    Mayer, Ian
    Kindhal, Hans
    Mature Atlantic salmon (Salmo salar L.) male parr are attracted to ovulated female urine but not to ovarian fluid2002Inngår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 28, nr 1, s. 29-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The behavioral responses to urine and ovarian fluids from conspecific and heterospecific ovulated females were studied in mature Atlantic salmon (Salmo salar) male parr in a two-choice fluviarium. The males reacted differently to the stimulants. They spent more time in water scented by urine from salmon or brown trout (Salmo trutta L.) females compared to the time in water with ovarian fluids from salmon females. Furthermore, the males were attracted to salmon female urine (different from an indifferent reaction). Males exposed to urine of either species had higher plasma concentrations of testosterone (T) compared to unexposed controls. Measurement of the concentrations of prostaglandin F-2alpha (PGF(2alpha)) and its major metabolite 15-ketodihydroprostaglandin F-2alpha (15-ketodihydro-PGF(2alpha)) showed that the concentrations of the substances were higher in ovarian fluids of both species compared to those in urine. PGF(2alpha) showed a greater difference between ovarian fluid and urine than its major metabolite. The results suggest that urine of both species, in contrast to ovarian fluid, contain substances that attract mature Atlantic salmon male parr and that the active substances are neither PGF(2alpha) nor 15-keto-PGF(2alpha).

  • 176.
    Para, Alessia
    Södertörns högskola, Avdelning Naturvetenskap. Uppsala universitet, Fysiologisk botanik.
    Meristem Maintenance in Arabidopsis thaliana2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The shoot apical meristem (SAM) is the structure that shapes the aerial architecture of the plant, by producing lateral organs throughout development. In the model plant Arabidopsis thaliana, the SAM is always identifiable as a characteristic dome, whether it is found in the centre of a rosette of leaves or at the tip of an inflorescence. When senescence occurs and organogenesis ceases, the now inactive SAM still retains its characteristic appearance and it is never consumed into a terminal structure, such as a flower. Mutant plants that undergo termination represent a valuable tool to understand how the SAM structure and function are maintained during plant life.

    The aim of this work was to investigate the dynamics of meristem development through morphological and genetic studies of three Arabidopsis mutants that exhibit distinct modes of SAM termination: distorted architecture 1 (dar1), adenosine kinase 1 (adk1) and terminal flower 2 (tfl2). The dar1 mutation is characterised by a severely distorted cellular architecture within the SAM. We propose that dar1 affects the pattern of cell differentiation and/or cell proliferation within the SAM apical dome, resulting in termination by meristem consumption. Instead, the adk1 mutation affects the organogenic potential of the SAM, without altering its structure. The adk1 mutant has increased levels of cytokinins and, as a consequence of this, cell division is enhanced and cell differentiation is prevented in the apex, causing termination by meristem arrest. Finally, tfl2 is mutated in the conserved chromatin remodelling factor HP1, a transcriptional repressor with multiple roles during plant development. The tfl2 SAM terminates by conversion into a floral structure, due to de-repression of floral identity genes. Interestingly, tfl2 mutants also show an altered response to light, an indication that TFL2 might act as a repressor also in the context of light signalling.

  • 177.
    Para, Alessia
    et al.
    Uppsala universitet, Fysiologisk botanik.
    Crona, Mikael
    Landberg, Katarina
    Datta, Sourav
    Holm, Magnus
    Sundås Larsson, Annika
    Södertörns högskola, Avdelning Naturvetenskap.
    TFL2, the Arabidopsis HP1 protein, is required to modulate light response during plant developmentManuskript (preprint) (Annet vitenskapelig)
  • 178.
    Para, Alessia
    et al.
    Uppsala universitet, Fysiologisk botanik.
    Nordström, Anders
    Sandberg, Göran
    Moffatt, Barbara
    Sundås Larsson, Annika
    Södertörns högskola, Avdelning Naturvetenskap.
    Disruption of the ADK1 gene causes meristems distortion and cytokinin syndrome in Arabidopsis thalianaManuskript (preprint) (Annet vitenskapelig)
  • 179.
    Para, Alessia
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Uppsala University.
    Sundås-Larsson, Annika
    Södertörns högskola, Avdelning Naturvetenskap.
    The pleiotropic mutation dar1 affects plant architecture in Arabidopsis thaliana2003Inngår i: Developmental Biology, ISSN 0012-1606, E-ISSN 1095-564X, Vol. 254, nr 2, s. 215-225Artikkel i tidsskrift (Fagfellevurdert)
  • 180. Pineda-Krch, Mario
    et al.
    Lehtilä, Kari
    Södertörns högskola, Avdelning Naturvetenskap.
    Cell lineage dynamics in stratified shoot apical meristems2002Inngår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 219, nr 4, s. 495-505Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We devise a stochastic and spatially explicit model for the dynamics of the initials cells in a stratified shoot apical meristem (SAM). The meristem is composed of three layers with seven initials per layer. We investigate the probability and number of divisions for a mutant lineage to either reach fixation or becoming purged through selection or drift. In contrast to previous studies our results show that the functional organization of the initials in stratified SAMs acts as an efficient purging mechanism particularly of deleterious mutations. All mutants are rapidly purged when deleterious. The probability of fixation for mutants with a higher fitness than the wild type increases linearly up to 70%. The median number of divisions to fixation of both genotypes is insensitive to the mutant's fitness. The median number of divisions to wildtype fixation is less than 100, with the upper quartile below 200. The largest number of divisions to wild-type fixation are in the order of 100 000 divisions. Our results indicate that the spatial organization of SAM enables the efficient purging of mutant lineages, particularly if they are deleterious. On the other hand, long-lived chimeric stages are common when mutant lineages succeed to overcome the initial numerical disadvantage.

  • 181. Pleijel, Fredrik
    et al.
    Härlin, Mikael
    Södertörns högskola, Avdelning Naturvetenskap.
    Phylogenetic nomenclature is compatible with diverse philosophical perspectives2004Inngår i: Zoologica Scripta, ISSN 0300-3256, E-ISSN 1463-6409, Vol. 33, nr 6, s. 587-591Artikkel i tidsskrift (Fagfellevurdert)
  • 182.
    Pooga, M
    et al.
    Stockholms universitet / Estonian Biocentre, Tartu, Estonia.
    Kut, Cecilia
    Södertörns högskola, Avdelning Naturvetenskap. Stockholms universitet.
    Kihlmark, Madeleine
    Södertörns högskola, Avdelning Naturvetenskap. Stockholms universitet.
    Hällbrink, M
    Stockholms universitet.
    Fernaeus, S
    Stockholms universitet.
    Raid, R
    Tartu University, Tartu, Estonia.
    Land, T
    Stockholms universitet.
    Hallberg, Einar
    Södertörns högskola, Avdelning Naturvetenskap.
    Bartfai, T
    Scripps Research Institute, USA.
    Langel, U
    Stockholms universitet / Scripps Research Institute, USA.
    Cellular translocation of proteins by transportan2001Inngår i: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 15, nr 8, s. 1451-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proteins with molecular masses ranging from 30 kDa. (green fluorescent protein, GFP) to 150 kDa (monoclonal and polyclonal antibodies) were coupled to the cellular translocating peptide transportan. We studied the ability of the resulting protein-peptide constructs to penetrate into Bowes melanoma, BRL, and COS-7 cells. After 0.5-3 h incubation with recombinant GFP coupled to transportan, most of the GFP fluorescence was found in intracellular membranes of BRL and COS-7 cells, which suggests that transportan could internalize covalently linked proteins of about 30 kDa in a folded state. Transportan could internalize covalently coupled molecules of even larger size; that is, avidin and antibodies, (up to 150 kDa). The covalent bond between the transport peptide and its cargo is not obligatory because streptavidin was translocated into the cells within 15 min as a noncovalent complex with biotinylated transportan. Inside the cells, the delivered streptavidin was first located mainly in close proximity to the plasma membrane and was later distributed to the perinuclear region. Most of the internalized streptavidin was confined to vesicular structures, but a significant fraction of the protein was distributed in the cytoplasm. Our data suggest that transportan can deliver proteins and other hydrophilic macromolecules into intact mammalian cells, and this finding demonstrates good potential as powerful cellular delivery vector for scientific and therapeutic purposes.

  • 183.
    Provost, P
    et al.
    Karolinska Institute.
    Silverstein, Rebecca A
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Dishart, D
    Karolinska Institute.
    Walfridsson, Julian
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Djupedal, Ingela
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Kniola, Barbara
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Wright, Anthony P H
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Samuelsson, B
    Karolinska Institute.
    Radmark, O
    Karolinska Institute.
    Ekwall, Karl
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Dicer is required for chromosome segregation and gene silencing in fission yeast cells2002Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 99, nr 26, s. 16648-16653Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    RNA interference is a form of gene silencing in which the nuclease Dicer cleaves double-stranded RNA into small interfering RNAs. Here we report a role for Dicer in chromosome segregation of fission yeast. Deletion of the Dicer (dcr1(+)) gene caused slow growth, sensitivity to thiabendazole, lagging chromosomes during anaphase, and abrogated silencing of centromeric repeats. As Dicer in other species, Dcr1p degraded double-stranded RNA into approximate to23 nucleotide fragments in vitro, and dcr1Delta cells were partially rescued by expression of human Dicer, indicating evolutionarily conserved functions. Expression profiling demonstrated that dcr1(+) was required for silencing of two genes containing a conserved motif.

  • 184.
    Ramula, Satu
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Mutikainen, Pia
    Sex allocation of females and hermaphrodites in the gynodioecious Geranium sylvaticum2003Inngår i: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 92, nr 2, s. 207-213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seed production and patterns of sex allocation were studied in female and hermaphroditic plants in two gynodioecious populations of Geranium sylvaticum (Geraniaceae). Females produced more flower buds and seeds than hermaphrodites in one of the two study populations. The other female traits measured (pistil biomass, seed number per fruit, individual seed mass) did not differ between the gender morphs. The relative seed fitness of hermaphrodites differed between the study populations, with hermaphrodites gaining less of their fitness through female function in the population with a high frequency of females. However, the amount and size of pollen produced by hermaphrodites did not differ between populations. The number of flower buds was positively correlated with seed production in females, whereas in hermaphrodites a positive correlation between number of buds and seed production was found in only one of the two study populations. These results suggest that fitness gain through female function is labile in hermaphrodites of this species, and is probably affected by environmental factors such as the sex ratio of the population.

  • 185. Rewcastle, G W
    et al.
    Janosik, Tomasz
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Reactions of 2-lithiated indoles with elemental sulfur. Formation of pentathiepino[6,7-b]indoles and indoline-2-thiones2001Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 57, nr 33, s. 7185-7189Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reactions of 2-lithiated indole and 1-methylindole with elemental sulfur have been studied, leading e.g. to a rational approach to pentathiepino[6,7-b]indoles 5 and 10. Notable amounts of the previously known tetrathiocino[5,6-b:8,7-b ' ]diindole 11 could be observed as a side reaction in the preparation of 10. Treatment of the anions of indoline-2-thiones 6 or 7 with sulfur also gave the pentathiepins 5 or 10, respectively. In addition, a convenient and clean lithiation route to indoline-2-thione (6) has been developed.

  • 186. Richards, J C
    et al.
    Cox, A D
    Schweda, Elke K H
    Södertörns högskola, Avdelning Naturvetenskap.
    Martin, A
    Hood, D W
    Moxon, E R
    Structure and functional genomics of lipopolysaccharide expression in Haemophilus influenzae2001Inngår i: MOLECULAR IMMUNOLOGY OF COMPLEX CARBOHYDRATES-2, 2001, s. 515-524Konferansepaper (Fagfellevurdert)
  • 187. Rietz, C.
    et al.
    Pilström, B.
    Brenden, N.
    Böhme, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Minute defects in the expression of MHC E molecules lead to impaired protection from autoimmunity in NOD mice1999Inngår i: Scandinavian Journal of Immunology, ISSN 0300-9475, E-ISSN 1365-3083, Vol. 50, nr 4, s. 405-410Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The E complex of the major histocompatibility complex (MHC) can prevent the spontaneous development of diabetes in nonobese diabetic (NOD) mice transgenic for the Ea gene. None of three promoter-mutated Ea constructs with Ea expression directed to different subsets of immunocompetent cells exerts full protection in NOD mice. The promoter-mutated constructs are all capable of mediating intrathymic elimination of I-E-restricted T cells. Thus, thymic negative selection is not responsible for the protective effect but a more complex effect is likely. Here we show that combinations of two or three different mutated Ea constructs do not protect against intra-islet insulitis either. We also show that spleen cells from protected animals are sufficient to protect NOD mice in adoptive transfer experiments. The only detectable expression defects in splenic cells or cells influencing the repertoire of splenic cells are in the B-cell compartment. Furthermore, in three construct combinations, the differences to wild-type expression are extremely small. Thus, we conclude that even minute disturbances of the E expression pattern might reduce the protection of NOD mice from insulitis.

  • 188. Rietz, C
    et al.
    Screpanti, V
    Brenden, N
    Böhme, Jan
    Södertörns högskola, Avdelning Naturvetenskap.
    Fernandez, C
    Overexpression of Bcl-2 in T cells affects insulitis in the nonobese diabetic mouse2003Inngår i: Scandinavian Journal of Immunology, ISSN 0300-9475, E-ISSN 1365-3083, Vol. 57, nr 4, s. 342-349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The nonobese diabetic (NOD) mouse is a useful model for human autoimmune diabetes. The gene for the anti-apoptotic protein Bcl-2 has previously been suggested as a probable susceptibility candidate for the NOD mouse disease. In this study, we investigated how overexpression of Bcl-2 in lymphocytes might affect insulitis in NOD mice. A bcl-2 transgene expressed constitutively under the SV40-promoter and the 5'Igh enhancer, Emu, was bred onto NOD background. Two bcl-2 transgenic NOD strains were produced and analysed, one with overexpression of Bcl-2 on only B cells and the other with overexpression of Bcl-2 on both B and T cells. Subsequent to verification of expression pattern and functionality of the transgene, insulitis intensity was investigated in different backcross generations of the two transgenic strains. Overexpression of Bcl-2 on both B and T cells leads to a statistically significant protection of the mice from insulitis compared with normal littermates. Overexpression of Bcl-2 on only B cells, on the other hand, does not have any statistically significant effect on insulitis. Possible mechanisms for the effect of Bcl-2 on insulitis in NOD mice are discussed.

  • 189. Romelsjö, A
    et al.
    Branting, Maria
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Hallqvist, J
    Alfredsson, L
    Hammar, N
    Leifman, A
    Ahlbom, A
    Abstention, alcohol use and risk of myocardial infarction in men and women taking account of social support and working conditions: the SHEEP case-control study2003Inngår i: Addiction, ISSN 0965-2140, E-ISSN 1360-0443, Vol. 98, nr 10, s. 1453-1462Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims Very few studies indicating that low-moderate alcohol consumption protects from myocardial infarction (MI) controlled for social support and working conditions, which could confound the findings. Therefore, a first aim was to study the risk of non-fatal and total MI in relation to volume of alcohol consumption and measures of social support and working conditions. A second aim was to analyse the impact of the volume of earlier alcohol use in abstainers. Design Data came from a case-control study, the Stockholm Heart Epidemiology Program (SHEEP), including first MI among Swedish citizens 45-70 years old. Setting Stockholm County 1992-94. Participants There were 1095 cases of MI in men and 471 in women (928 and 3 72 were non-fatal), and 2339 living controls from the general population. Measurement Information about alcohol use at different periods in life and job strain, social anchorage and life control besides pre-existing health problems, smoking, physical activity, socio-economic status and marital status was obtained by a questionnaire from the cases and the controls. Findings In multivariate logistic regression analyses, the relative risk for MI (especially non-fatal) was reduced among alcohol consumers. RR for non-fatal MI was 0.52 (95% confidence intervals 0.32, 0.85) in men with a consumption of 50-69.9 g 100% ethanol/day and 0.21 (95% confidence interval 0.06, 0.77) in women with a consumption of 30 g or more per day (reference category 0.1-5 g 100% ethanol/day). Men who were abstainers during the previous 1-10 years and with an earlier average consumption of 5-30 g 100% ethanol/day had a significantly lower relative risk compared to such abstainers with an earlier higher consumption. Earlier consumption among abstainers may also have an impact on gender differences in MI. Analyses showed positive interaction between abstention and low life-control in women, but only 4% of the female cases were due to this interaction. There were no other interactions between measures of alcohol use and social anchorage, life control and working situations. Conclusion Alcohol use had a protective impact on MI, with little impact of job strain, social anchorage and life control, giving increased support for a protective impact of low-moderate alcohol use. The level of previous alcohol consumption among male 1-10-year-long abstainers influenced the risk of MI.

  • 190. Ruda, M C
    et al.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Koehler, K
    Liu, Y
    A solution-phase procedure for the preparation of 4-azasteroid numetics2003Inngår i: Heterocyclic Communications, ISSN 0793-0283, E-ISSN 2191-0197, Vol. 9, nr 6, s. 571-574Artikkel i tidsskrift (Fagfellevurdert)
  • 191. Ruda, M C
    et al.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Wu, J
    Preparation of N-alkylated pyridones via selective N-alkylation of 2-alkoxypyridines on solid phase2002Inngår i: Journal of combinatorial chemistry, ISSN 1520-4766, E-ISSN 1520-4774, Vol. 4, nr 5, s. 530-535Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Regioselective solid-phase synthesis of N-alkylated 2-pyridones has been carried out starting from 2-halopyridines. Variously substituted 2-halopyridines were linked to a Wang resin in quantitative yields to afford 2-alkoxypyridines. The coupled products were then reacted with a variety of alkyl halides, resulting in tandem alkylation and cleavage from the resin to generate N-alkylated pyridones With no detectable traces of O-alkylated products. The scope and limitations of this exceptionally selective reaction have been studied.

  • 192. Räsänen, L A
    et al.
    Elväng, A M
    Jansson, Janet
    Södertörns högskola, Avdelning Naturvetenskap.
    Lindström, K
    Effect of heat stress on cell activity and cell morphology of the tropical rhizobium, Sinorhizobium arboris2001Inngår i: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 34, nr 3, s. 267-278Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of heat stress oil the growth, physiological state, cell activity and cell morphology of the tropical Sinorhizobium ariboris strain HAMBI 2190 was studied. The cells were chromosomally tagged with the firefly luciferase gene, luc. Since the bioluminescence phenotype is dependent on cellular energy reserves it was used as an indicator of the metabolic status of the cell population under various heat conditions. Variations in the numbers and lengths of growth phases between individual cultures indicated that the growth pattern at 40 degreesC was disturbed compared to growth at 37 or 28 degreesC. In addition, the cell morphology was changed radically. The number of culturable cells and the luciferase activity declined when the cultures were incubated at 40 degreesC. By contrast, under all conditions studied, the cells could be stained with 5-(and 6-)sulfofluorescein diacetate, indicating esterase activity. This demonstrated that although the culturability and cellular energy reserves decreased considerably during heat stress, a majority of the of S. arboris cell population maintained basal enzyme activity.

  • 193. Saglio, P
    et al.
    Bretaud, S
    Rivot, E
    Olsén, K Håkan
    Södertörns högskola, Avdelning Naturvetenskap.
    Chemobehavioral changes induced by short-term exposures to prochloraz, nicosulfuron, and carbofuran in goldfish2003Inngår i: Archives of Environmental Contamination and Toxicology, ISSN 0090-4341, E-ISSN 1432-0703, Vol. 45, nr 4, s. 515-524Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The behavioral effects of short periods (2, 4, 6, 8 h) of static exposure to prochloraz (imidazole fungicide) and nicosulfuron (sulfonylurea herbicide) were recorded in goldfish (Carassius auratus). Observations were also made in an olfactometer to assess the effects of 8-h exposures to these two pesticides and to carbofuran (carbamate insecticide) on the behavioral responses to the flow of a solution of four L-amino acids (glycine, alanine, valine, taurine), mixed in the same relative proportions as in the urine of conspecifics. Each pesticide was tested at three sublethal concentrations (25, 50, 100 mug/L), and the behaviors recorded were related to swimming pattern, social interactions, and comfort movements. Static exposures to prochloraz affected horizontal displacements, burst swimming, grouping, and buccal movements. Static exposures to nicosulfuron affected burst swimming and grouping. In pesticide-unexposed fish (control), the flow of the amino acid solution induced attraction, decreased sheltering, and increased horizontal displacements, burst swimming, buccal movements, and antagonistic interactions. Compared to the controls, some of the behavioral responses to the solution of amino acids were significantly different after 8 It of subacute exposure to prochloraz and carbofuran. Both pesticides decreased attraction and increased sheltering. In addition, carbofuran decreased buccal movements and antagonistic interactions. Contrastingly, exposure to nicosulfuron showed no significant effect. This study further confirms the great vulnerability of fish behavior and chemocommunication processes to exposure to waterborne pesticides.

  • 194. Schafer, J C
    et al.
    Haycraft, C J
    Thomas, J H
    Yoder, B K
    Swoboda, Peter
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    XBX-1 encodes a dynein light intermediate chain required for retrograde intraflagellar transport and cilia assembly in Caenorhabditis elegans2003Inngår i: Molecular Biology of the Cell, ISSN 1059-1524, E-ISSN 1939-4586, Vol. 14, nr 5, s. 2057-2070Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Intraflagellar transport (IFT) is a process required for flagella and cilia assembly that describes the dynein and kinesin mediated movement of particles along axonemes that consists of an A and a B complex, defects in which disrupt retrograde and anterograde transport, respectively. Herein, we describe a novel Caenorhabditis elegans gene, xbx-1, that is required for retrograde IFT and shares homology with a mammalian dynein light intermediate chain (D2LIC). xbx-1 expression in ciliated sensory neurons is regulated by the transcription factor DAF-19, as demonstrated previously for genes encoding IFT complex B proteins. XBX-1 localizes to the base of the cilia and undergoes anterograde and retrograde movement along the axoneme. Disruption of xbx-1 results in cilia defects and causes behavioral abnormalities observed in other cilia mutants. Analysis of cilia in xbx-1 mutants reveals that they are shortened and have a bulb like structure in which IFT proteins accumulate. The role of XBX-1 in IFT was further confirmed by analyzing the effect that other IFT mutations have on XBX-1 localization and movement. In contrast to other IFT proteins, retrograde XBX-1 movement was detected in complex A mutants. Our results suggest that the DLIC protein XBX-1 functions together with the CHE-3 dynein in retrograde IFT, downstream of the complex A proteins.

  • 195.
    Schubert, Maria
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Petersson, Ulrika A
    Södertörns högskola, Avdelning Naturvetenskap. Stockholm University.
    Haas, B J
    Institute for Genomic Research, Rockville, USA.
    Funk, C
    Stockholm University.
    Schröder, Wolfgang P
    Södertörns högskola, Avdelning Naturvetenskap.
    Kieselbach, T
    Karolinska Institute.
    Proteome map of the chloroplast lumen of Arabidopsis thaliana2002Inngår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 277, nr 10, s. 8354-8365Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The thylakoid membrane of the chloroplast is the center of oxygenic photosynthesis. To better understand the function of the luminal compartment within the thylakoid network, we have carried out a systematic characterization of the luminal thylakoid proteins from the model organism Arabidopsis thaliana. Our data show that the thylakoid lumen has its own specific proteome, of which 36 proteins were identified. Besides a large group of peptidyl-prolyl cis-trans isomerases and pro. teases, a family of novel PsbP domain proteins was found. An analysis of the luminal signal peptides showed that 19 of 36 luminal precursors were marked by a twin-arginine motif for import via the Tat pathway. To compare the model organism Arabidopsis with another typical higher plant, we investigated the proteome from the thylakoid lumen of spinach and found that the luminal proteins from both plants corresponded well. As a complement to our experimental investigation, we made a theoretical prediction of the luminal proteins from the whole Arabidopsis genome and estimated that the thylakoid lumen of the chloroplast contains similar to80 proteins.

  • 196.
    Schuisky, P
    et al.
    SLU.
    Twistel, W
    SLU.
    Grivas, Spiros
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute / SLU.
    Synthesis, H-1 and C-13 NMR spectra, and configurational assignment of furfurylideneimidazolinones1998Inngår i: Heterocycles, ISSN 0385-5414, E-ISSN 1881-0942, Vol. 48, nr 7, s. 1431-1444Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The title compounds (14 and 15) were obtained by the condensation of a 2- or 3-furaldehyde derivative (prepared from 2-methylfuran) with 2-amino-1-methyl-2-imidazolin-4-one (6) or -5-one (7). Most products from 6 contained the (E)- and (Z)-isomers in comparable amounts; in those from 7, the (Z) -isomer generally predominated. The isomers were distinguished by their H-1 and C-13 NMR spectra, in particular by the three-bond coupling between the carbonyl carbon and the olefinic hydrogen. This led to configurational reassignment of some previously reported analogues.

  • 197.
    Schweda, Elke K H
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Brisson, J R
    Alvelius, G
    Martin, A
    Weiser, J N
    Hood, D W
    Moxon, E R
    Richards, J C
    Characterization of the phosphocholine-substituted oligosaccharide in lipopolysaccharides of type b Haemophilus influenzae2000Inngår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 267, nr 12, s. 3902-3913Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Haemophilus influenzae expresses heterogeneous populations of short-chain lipopolysaccharide (LPS) which exhibit extensive antigenic diversity among multiple oligosaccharide epitopes. These LPS oligosaccharide epitopes can carry phosphocholine (PCho) substituents, the expression of which is subject to high frequency phase variation mediated by genes in the lic1 genetic locus. The location and site of attachment of PCho substituents were determined by structural analysis of LPS from two type b H. influenzae strains, Eagan and RM7004. The lic2 locus is involved in phase variation of oligosaccharide expression. LPS obtained from the parent strains, from mutants generated by insertion of antibiotic resistance cassettes in the lic2 genetic locus, and from phase-variants showing high levels of PCho expression was characterized by electrospray ionization-mass spectrometry (ESI-MS) and H-1 NMR spectroscopy of derived O-deacylated samples. ESI-MS of O-deacylated LPS from wild-type strains revealed mixtures of related glycoform structures differing in the number of hexose residues. Analysis of LPS from PCho-expressing phase-variants revealed similar mixtures of glycoforms, each containing a single PCho substituent. O-Deacylated LPS preparations from the lic2 mutants were much less complex than their respective parent strains, consisting only of Hex3 and/or Hex2 glycoforms, were examined in detail by high-field NMR techniques. It was found that the LPS samples contain the phosphoethanolamine (PEtn) substituted inner-core element, L-alpha-D-Hepp-(1-->2)-[PEtn-->6]-L-alpha-D-Hepp-(1-->3)-L-alpha-D-Hepp- (1-->5)-alpha-Kdo in which the major glycoforms carry a beta-D-Glcp or beta-D-Glcp-(1-->4)-beta-D-Glcp at the O-4 position of the 3-substituted heptose (HepI) and a beta-D-Galp at the O-2 position of the terminal heptose (HepIII). LPS from the lic2 mutants of both type b strains were found to carry PCho groups at the O-6 position of the terminal beta-D-Galp residue attached to HepIII. In the parent strains, the central heptose (HepII) of the LPS inner-core element is also substituted by hexose containing oligosaccharides. The expression of the galabiose epitope in LPS of H. influenzae type b strains has previously been linked to genes comprising the lic2 locus. The present study provides definitive evidence for the role of lic2 genes in initiating chain extension from HepII. From the analysis of core oligosaccharide samples, LPS from the lic2 mutant strain of RM7004 was also found to carry O-acetyl substituents. Mono-, di-, and tri-O-acetylated LPS oligosaccharides were identified. The major O-acetylated glycoforms were found to be substituted at the O-3 position of HepIII. A di-O-acetylated species was characterized which was also substituted at the O-6 postion of the terminal beta-D-Glc in the Hex3 glycoform. This is the first report pointing to the occurrence of O-acetyl groups in the inner-core region of H. influenzae LPS. We have previously shown that in H. influenzae strain Rd, a capsule-deficient type d strain, PCho groups are expressed in a different molecular environment, being attached at the O-6 position of a beta-D-Glcp, which is in turn attached to HepI.

  • 198.
    Schweda, Elke K H
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Landerholm, Malin K
    Södertörns högskola, Avdelning Naturvetenskap.
    Li, J J
    Moxon, E R
    Richards, J C
    Structural profiling of lipopolysaccharide glycoforms expressed by non-typeable Haemophilus influenzae: phenotypic similarities between NTHi strain 162 and the genome strain Rd2003Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 338, nr 23, s. 2731-2744Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Non-typeable Haemophihis influenzae (NTHi) is a significant cause of otitis media in children. We have employed single and multiple step electrospray ionization mass spectrometry (ESIMS) and NMR spectroscopy to profile and elucidate lipopolysaccharide (LPS) structural types expressed by NTHi strain 162, a strain obtained from an epidemiological study in Finland. ESIMS on O-deacylated LPS (LPS-OH) and core oligosaccharide (OS) samples of LPS provided information on the composition and relative abundance of glycoforms differing in the number of hexoses linked to the conserved inner-core element, L-alpha-D-Hepp-(1--> 2)-[PEtn --> 6]-L-alpha-D-Hepp-(1 --> 3)-L-alpha-D-Hepp-(1 --> 5)(.)[PPEtn --> 4]-alpha-Kdop-(2 --> 6)-Lipid A of H. influenzae LPS. The strain examined was found to elaborate Hex2 to Hex5 LPS glycoform populations having structures identical to those observed for H. influenzae strain Rd [Risberg, A.; Masoud, H.; Martin, A.; Richards, J.C.; Moxon, E.R.; Schweda, E.K.H. Eur. J Biochem. 1999, 261, 171-180], the strain for which the complete genome has been sequenced. In addition, sialyllactose-containing glycoforms previously identified in strain Rd as well as several NTHi strains, were identified as minor components. Multiple step tandem ESIMS (MS") on dephosphorylated and permethylated OS provided information on the arrangement of glycoses within the major population of glycoforms and on the existence of additional isomeric glycoforms. Minor Hex1 and Hex6 glycoforms were detected and characterized where the Hex6 glycoform was comprised of a dihexosamine-containing pentasaccharide chain attached at the proximal heptose residue of the inner-core unit. LPS structural motifs present in the NTHi strain 162 are expressed by a genetically diverse set of disease causing isolates, providing the basis for a vaccine strategy against NTHi otitis media.

  • 199.
    Schweda, Elke K H
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Li, J J
    Moxon, E R
    Richards, J C
    Structural analysis of lipopolysaccharide oligosaccharide epitopes expressed by non-typeable Haemophilus influenzae strain 1762002Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 337, nr 5, s. 409-420Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure of the lipopolysaccharide (LPS) from non-typeable Haemophilus influenzae strain 176 has been investigated. Electrospray ionization-mass spectrometry (ESIMS) on O-deacylated LPS (LPS-OH) and core oligosaccharide (OS) samples obtained after mild-acid hydrolysis of LPS provided information on the composition and relative abundance of the glycoforms. ESIMS tandem-mass spectrometry on LPS-OH confirmed the presence of minor sialylated and disialylated glycoforms. Oligosaccharide samples were studied in detail using high-field NMR techniques. It was found that the LPS contains the common inner-core element of H. influenzae. L-alpha-D-Hepp-(1-->2)-[PEtn-->6]-L-alpha-D-Hepp-(1-->3)-[beta-D-Glep-(1 -->4)]-L-alpha-D-Hepp-(1-->5)[PPEtn-->4]-alpha-Kdop-(2-->6)-Lipid A having glycosyl substitution at the O-3 position of the terminal heptose as recently observed for non-typeable H. influenzae strain 486 [Mansson, M.: Bauer. S. H. J.: Hood, D. W.; Richards, J. C. Moxon, E. R. Schweda. E. K. H., Eur. J. Biochem. 2001. 268. 2148-2159]. The following LPS structures were identified as the major glycoforms. the most significant being indicated with an asterisk (*) (glycoforms are partly substituted with Gly at the terminal Hep): [GRAPHICS].

  • 200. Shi, L X
    et al.
    Kim, S J
    Marchant, A
    Robinson, C
    Schröder, Wolfgang P
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Characterisation of the PsbX protein from Photosystem II and light regulation of its gene expression in higher plants1999Inngår i: Plant Molecular Biology, ISSN 0167-4412, E-ISSN 1573-5028, Vol. 40, nr 4, s. 737-744Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The location and expression of the previously uncharacterised photosystem II subunit PsbX have been analysed in higher plants. We show that this protein is a component of photosystem II (PSII) core particles but absent from light-harvesting complexes or PSII reaction centres. PsbX is, however, localised to the near vicinity of the reaction centre because it can be cross-linked to cytochrome b559, which is known to be associated with the D1/D2 dimer. We also show that the expression of this protein is tightly regulated by light, since neither protein nor mRNA is found in dark-grown plants.

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