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  • 1. Abrahamsson, K
    et al.
    Ekdahl, A
    Collén, J
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Pedersen, M
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Marine algae - a source of trichloroethylene and perchloroethylene1995In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 40, no 7, p. 1321-1326p. 1321-1326Article in journal (Refereed)
    Abstract [en]

    Our results show the natural production of two olefins, trichloroethylene and perchloroethylene, by various marine macroalgae and a microalga. We found significant difference in the ability of the algae to produce these compounds. The production rates for trichloroethylenevaried between 0.022 and 3,400 ng g-l fresh wt (FW)h-l and were generally higher than those for perchloroethylene(0.0026-8.2 ng g-l FW h-l). The two subtropicalalgae, Asparagopsis taxiformis and Falkenbergia hillebrandii,showed the highest formation rates. One axenicmarine red microalga, Porphyridium purpureum, was alsotested and it could also produce trichloroethylene and perchloroethylene.The measured rates suggest that the emissionof trichloroethylene and perchloroethylene from theoceans to the atmosphere may be of such a magnitude thatit cannot be neglected in the global atmospheric chlorinebudget.

  • 2. Elhai, Jeff
    et al.
    Kato, Michiko
    Cousins, Sarah
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Costa, Jose Luis
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Very small mobile repeated elements in cyanobacterial genomes2008In: Genome Research, ISSN 1088-9051, E-ISSN 1549-5469, Vol. 18, no 9, p. 1484-1499Article in journal (Refereed)
    Abstract [en]

    Mobile DNA elements play a major role in genome plasticity and other evolutionary processes, an insight gained primarily through the study of transposons and retrotransposons (generally similar to 1000 nt or longer). These elements spawn smaller parasitic versions (generally > ; 100 nt) that propagate through proteins encoded by the full elements. Highly repeated sequences smaller than 100 nt have been described, but they are either nonmobile or their origins are not known. We have surveyed the genome of the multicellular cyanobacterium, Nostoc punctiforme, and its relatives for small dispersed repeat (SDR) sequences and have identified eight families in the range of from 21 to 27 nucleotides. Three of the families (SDR4, SDR5, and SDR6), despite little sequence similarity, share a common predicted secondary structure, a conclusion supported by patterns of compensatory mutations. The SDR elements are found in a diverse set of contexts, often embedded within tandemly repeated heptameric sequences or within minitransposons. One element ( SDR5) is found exclusively within instances of an octamer, HIP1, that is highly over-represented in the genomes of many cyanobacteria. Two elements (SDR1 and SDR4) often are found within copies of themselves, producing complex nested insertions. An analysis of SDR elements within cyanobacterial genomes indicate that they are essentially confined to a coherent subgroup. The evidence indicates that some of the SDR elements, probably working through RNA intermediates, have been mobile in recent evolutionary time, making them perhaps the smallest known mobile elements.

  • 3.
    Gambäck Keyser, Pia
    Uppsala University, Department of Physiological Botany.
    Crustacean immunity: Characterization of some crayfish blood proteins1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The cDNA sequence and some properties of a previously purified #x03B2;-1,3-glucan binding protein are reported here. The putative amino acid sequence (predicted molecular mass: 152 kDa) of the protein did not show any significant similarity to any known protein, but an RGD motif and a region with slight similarity to bacterial glucanase was found. The RDG motif may be involved in the blood cell degranulating activity of this molecule although it was not possible to prevent binding of the protein to crayfish blood cells (haemocytes) by pre-treating cells with a short peptide containing RGD. No glucanase activity could be detected. Carbohydrate analysis showed that the protein is a glycoprotein with mannose as the main sugar constituent. It was also found that this protein can function as an opsonin.

    With in situ hybridisation the expression of prophenoloxidase was detected in the circulating haemocytes, but not in the haematopoietic tissue of crayfish. Thus, cells are not fully developed in the haematopoietic tissue. With an injection of laminarin, a #x03B2;-1,3-glucan, it was possible to increase expression of proPO in haemoyctes in the species Astacus astacus, but not in Pacifastacus Ieniusculus. The chronic infection of the crayfish plague, Aphanomyces astaci, in P. leniusculus might already have induced the immune system, thus no further increase is possible. In contrast, A. astacus with a latent infection of the parasite Psorospermium haeckeli did not show any upregulation in the expression of proPO compared to control animals.

    Cloning and purification of a 23 kDa Kasal proteinase inhibitor from haemocytes are re-ported. The activity against chymotrypsin and subtilisin suggests a possible role as inhibitorof microbe proteinases.

    A high mobility group-1/2 protein was cloned from a cDNA library made from crayfishblood cells. The predicted amino acid sequence with a mass of 23 kDa has two so-calledHMG-boxes and an acid C-terminal tail. The transcript is present in haemocytes, muscle,and hepatopancreas in adult animals. It shows highest similarity to the dorsal switch protein(DSP1) found in Drosophila melanogaster.

  • 4.
    Groth, Erika
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Evolution of Genetic Mechanisms Regulating Reproductive Development in Seed Plants2007Licentiate thesis, comprehensive summary (Other academic)
    List of papers
    1. Evolutionary conservation of protein-protein interaction ability in MIKC and Malpha MADS-box transcription factors in seed plants
    Open this publication in new window or tab >>Evolutionary conservation of protein-protein interaction ability in MIKC and Malpha MADS-box transcription factors in seed plants
    (English)Manuscript (preprint) (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-149896 (URN)
    Available from: 2011-03-24 Created: 2011-03-24 Last updated: 2011-03-24
    2. Conservation of alternative splicing in TM3-like MIKC-type MADS-domain transcription factors in conifers
    Open this publication in new window or tab >>Conservation of alternative splicing in TM3-like MIKC-type MADS-domain transcription factors in conifers
    (English)Manuscript (preprint) (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-149897 (URN)
    Available from: 2011-03-24 Created: 2011-03-24 Last updated: 2011-03-24
  • 5.
    Nilsson, Lars
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Carlsbecker, Annelie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Sundås Larsson, Annika
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiological Botany.
    Vahala, Tiina
    APETALA2 like genes from Picea abies show functional similarities to their Arabidopsis homologues2007In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 225, no 3, p. 589-602Article in journal (Refereed)
    Abstract [en]

    In angiosperm flower development the identity of the floral organs is determined by the A, B and C factors. Here we present the characterisation of three homologues of the A class gene APETALA2 (AP2) from the conifer Picea abies (Norway spruce), Picea abies APETALA2 LIKE1 (PaAP2L1), PaAP2L2 and PaAP2L3. Similar to AP2 these genes contain sequence motifs complementary to miRNA172 that has been shown to regulate AP2 in Arabidopsis. The genes display distinct expression patterns during plant development; in the female-cone bud PaAP2L1 and PaAP2L3 are expressed in the seed-bearing ovuliferous scale in a pattern complementary to each other, and overlapping with the expression of the C class-related gene DAL2. To study the function of PaAP2L1 and PaAP2L2 the genes were expressed in Arabidopsis. The transgenic PaAP2L2 plants were stunted and flowered later than control plants. Flowers were indeterminate and produced an excess of floral organs most severely in the two inner whorls, associated with an ectopic expression of the meristem-regulating gene WUSCHEL. No homeotic changes in floral-organ identities occurred, but in the ap2-1 mutant background PaAP2L2 was able to promote petal identity, indicating that the spruce AP2 gene has the capacity to substitute for an A class gene in Arabidopsis. In spite of the long evolutionary distance between angiosperms and gymnosperms and the fact that gymnosperms lack structures homologous to sepals and petals our data supports a functional conservation of AP2 genes among the seed plants.

  • 6.
    Oxelfelt, Fredrik
    Uppsala University, Department of Physiological Botany.
    Hydrogenases in the Cyanobacterium Nostoc sp. Strain PCC 731021998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Many cyanobacteria are capable of fixing atmospheric N2, a reaction that is also producing H2. This hydrogen is often metabolized by an enzyme called hydrogenase. The aim of the present work was to identify and characterize hydrogen metabolism/hydrogenases in the free-living N2-fixing cyanobacterium Nostoc sp.strain PCC 73102. With immunological techniques it was revealed that Nostoc PCC 73102 contains proteins that are immunologically related to hydrogenases from other microorganisms and that these proteins seem to be present in both the vegetative cells and the heterocysts. A light-dependent hydrogen uptake was detected in nitrogen-fixing cells of Nostoc PCC 73102. This hydrogen uptake is positively regulated by the substrate H2. Furthermore, the in vivo nitrogenase and uptake hydrogenase activities appear to be co-regulated when nitrogen-fixing cells are exposed to either combined nitrogen or organic carbon sources. Using both physiological and molecular techniques, no evidence could be found for the presence of a reversible/bidirectional hydrogenase in Nostoc PCC 73102. The characterization of the structural genes encoding the uptake hydrogenase in Nostoc PCC 73102 demonstrated a high sequence identity with the sequence of the cyanobacterium Anabaena PCC 7120, but a high degree of difference in comparison with sequences from other microorganisms. In addition, Nostoc PCC 73102 appears not to perform a site specific rearrangement within hupL. Furthermore, in a Nostoc strain containing both an uptake- and a bidirectional hydrogenase, an induction of a hupL transcript was evident after a shift from non-nitrogen fixing to nitrogen fixing conditions.

  • 7.
    Söderman, Eva
    Uppsala University, Department of Physiological Botany.
    Genes encoding homeodomain-leucine zipper proteins in Arabidopsis thaliana1996Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A new class of transcription factors, the homeodomain-leucine zipper (HD-Zip) proteins,have been identified in Arabidopsis thaliana. These proteins contain a homeodomainfollowed by a leucine-zipper motif, a combination so far only found in plants. Sixdifferent genes (ATHB-genes for Arabidopsis thaliana homeobox) which encode proteinsin this class, have been isolated in this study. The HD-Zip class of Arabidopsis includesmore than 20 members in total, the majority ate of unknown function. Analysis ofmRNA expression, shows the isolated genes to be expressed at various levels during thevegetative stage of the plant life cycle.

    The first gene isolated, ATHB-3, showed a high level of expression in the cortexcells of the root and stem. The function of this gene is unknown. The functions of twoother genes, ATHB-6 and ATHB-7 were found to be involved in the control of vegetativegrowth, in response to water availability. ATHB-6 and ATHB-7 are induced by waterdeficit as well as by the plant hormone abscisic acid (ABA). The expression of ATHB-7was reduced in the ABA insensitive, abi1 mutant background indicating that ATHB-7functions downstream of ABI1 in a signal transduction pathway of an ABA mediateddrought stress response. Transgenic Arabidopsis plants, expressing ATHB-7 at highlevels show a reduction in growth elongation consistent with ATHB-7 regulating cell-elongation in response to drought. An ATHB-6 promoter-marker gene fusion intransgenic Arabidopsis showed ATHB-6 to be expressed in the developing anddifferentiating cells of the leaf and root, suggesting ATHB-6 to be a developmentalregulator in these tissues.

    Taken together, the results presented in this study show that plants, like animals, usehomeobox genes as transcription factors to control different developmental processes. Incontrast to animal homeobox genes, which act in the control of embryonal development,the plant homeobox genes of the HD-Zip class seem to be important regulators of plantdevelopment and differentiation in response to environmental factors.

  • 8.
    Tandre, Karolina
    Uppsala University, Department of Physiological Botany.
    Molecular approaches to the developmental biology of Norway spruce, Picea abies1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ontogeny depends on the developmental control of genes. In this thesis twoapproaches were taken to identify genes essential to developmental processes inthe conifer Norway spruce, Picea abies (L.) Karst. Firstly, development of vegetative meristems was studied in a model system for de novo formation ofmeristems on zygotic embryos in vitro, induced by a cytokinin treatment. As areference process germinative development was analysed. By differentialscreening, clones representing genes with differential expression in relation tothese processes were isolated. Meristem induction quantitatively affected the expression of genes which had a differential expression pattern in relation togermination. Genes coding for histone H2A, α-tubulin, chlorophyll a/b bindingprotein, chloroplast ribosomal protein S7, polyubiquitin and β-1,3-glucanase wereidentified. None of the cloned genes were active specifically in developingmeristems, their differential expression instead reflecting activity in dividing versuselongating and differentiating cells. Expression of the histone H2A gene wastightly linked to cell proliferation. In contrast, the expression of a sprucehomologue to the cell cycle control gene CDC2, was not strictly coupled to cellproliferation.

    In the second part of the work the development of reproductive organs wasapproached by taking advantage of recent results on angiosperm flowerontogeny. Flower development is controlled by MADS-box genes, coding fortranscription factors. Three MADS-box genes, DAL1, DAL2 and DAL3, wereisolated from spruce. A phylogenetic analyses, based on primary sequence,identified DAL2 as structurally most closely related to class C MADS-box genescontrolling carpel and stamen identity in angiosperms and suggested that thelast common ancestor of conifers and angiosperms had at least three differentMADS-box genes. DAL2 was expressed only in cones. In the female coneDAL2 expression was detected specifically in ovuliferous scales, but not insterile bracts. In transgenic Arabidopsis thaliana DAL2 caused homeotictransformations of flower organs, previously recorded specifically forangiospermclass C MADS-box genes. Thus, DAL2 and class C genes likelyshare a common origin and have a conserved function in control of ontogeny ofthe ovule-bearing organs in conifers and angiosperms.

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