sh.sePublications
Change search
Refine search result
1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • harvard-anglia-ruskin-university
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Janson, Sven
    et al.
    Department of Marine Sciences, University of Kalmar.
    Wouters, Johanna
    Department of Botany, Stockholm University.
    Bergman, Birgitta
    Department of Botany, Stockholm University.
    Carpenter, Edward J.
    Marine Sciences Research Center, Stony Brook, NY.
    Host specificity in the Richelia - diatom symbiosis revealed by hetR gene sequence analysis1999In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 1, no 5, p. 431-438Article in journal (Refereed)
    Abstract [en]

    The filamentous heterocyst-forming cyanobacterium Richelia intracellularis forms associations with diatoms and is very abundant in tropical and subtropical seas. The genus Richelia contains only one species, R. intracellularis Schmidt, although it forms associations with several diatom genera and has considerable variation in size and morphology. The genetic diversity, and possible host specificity, within the genus Richelia is unknown. Using primers against hetR, a gene unique for filamentous cyanobacteria, specific polymerase chain reaction (PCR) products were obtained from natural populations of R. intracellularis filaments associated with three diatom genera. Phylogenetic analyses of these sequences showed that they were all in the same clade. This clade contained only the R. intracellularis sequences. The genetic affiliation of hetR sequences of R. intracellularis to those of other heterocystous cyanobacteria strongly suggests that it was not closely related to endosymbiotic Nostoc spp, hetR sequences. Sequences from R, intracellularis-Hemiaulus membranaceus sampled in the Atlantic and Pacific Oceans were almost identical, demonstrating that the genetic relatedness was not dependent on geographical location, All sequences displayed a deep divergence between symbionts from different genera and a high degree of host specificity.

  • 2.
    Janson, Sven
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies.
    Wouters, Johanna
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology.
    Bonow, Madeleine
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Geography.
    Svanberg, Ingvar
    Uppsala University.
    Olsén, K. Håkan
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology.
    Population genetic structure of crucian carp (Carassius carassius) in man-made ponds and wild populations in Sweden2015In: Aquaculture International, ISSN 0967-6120, E-ISSN 1573-143X, Vol. 23, no 1, p. 359-368Article in journal (Other academic)
    Abstract [en]

    Although once popular prior to the last century, the aquaculture of crucian carp Carassius carassius (L. 1758) in Sweden gradually fell from favour. This is the first genetic comparison of crucian carp from historic man-made ponds in the Scandinavian Peninsula. The aim was to identify old populations without admixture and to compare the relationship of pond populations from different provinces in Sweden. In total, nine microsatellite loci from 234 individuals from 20 locations in varied parts of Sweden were analysed. The genetic distances of crucian carp populations indicated that the populations in the southernmost province of Sweden, Scania, shared a common history. A pond population in the province Småland also showed a common inheritance with this group. In the province Uppland, further north in Sweden, the population genetic distances suggested a much more complex history of crucian carp distributions in the ponds. The data showed that there are some ponds with potentially old populations without admixture, but also that several ponds might have been stocked with fish from many sources. © 2014 The Author(s).

  • 3.
    Wouters, Johanna
    Kalmar University.
    Heterocystous cyanobacteria living within symbiosomes: genetic and physiological aspects2005Doctoral thesis, comprehensive summary (Other academic)
  • 4.
    Wouters, Johanna
    et al.
    Department of Biology and Environmental Science, University of Kalmar.
    Bergman, Birgitta
    Department of Botany, Stockholm University.
    Janson, Sven
    Department of Biology and Environmental Science, University of Kalmar.
    Cloning and expression of a putative cyclodextrin glucosyltransferase from the symbiotically competent cyanobacterium Nostoc sp PCC 92292003In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 219, no 2, p. 181-185Article in journal (Refereed)
    Abstract [en]

    A polymerase chain reaction-based method was used to isolate a Nostoc sp. PCC 9229 cDNA from infected glands of Gunnera chilensis. The complete gene sequence was isolated from a genomic Nostoc sp. PCC 9229 library. Sequence analysis showed 84% amino acid similarity to a putative cyclodextrin glycosyltransferase from Nostoc sp. PCC 7120 and the gene was therefore termed cgt. Southern blot revealed that the cgt gene was present in symbiotically competent cyanobacteria. The cgt gene was expressed in free-living nitrogen-fixing cultures in light or in darkness when supplemented with fructose. This is the first expression analysis of a cgt gene from a cyanobacterium. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

  • 5.
    Wouters, Johanna
    et al.
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Elväng, Anneli
    Pawlowski, Katarina
    Bergan, Brigitta
    Sucrose synthase and glutamine synthetase expression in greenhouse cultivated Gunnera manicata forming symbiosis with Nostoc sp.Manuscript (preprint) (Other academic)
  • 6.
    Wouters, Johanna
    et al.
    Department of Botany, Stockholm University.
    Janson, Sven
    Department of Marine Sciences, Kalmar University.
    Bergman, Birgitta
    Department of Botany, Stockholm University.
    The effect of exogenous carbohydrates on nitrogen fixation and hetR expression in Nostoc PCC 9229 forming symbiosis with Gunnera2000In: Symbiosis, ISSN 0334-5114, E-ISSN 1878-7665, Vol. 28, no 1, p. 63-76Article in journal (Refereed)
    Abstract [en]

    The cyanobacterium Nostoc PCC 9229 forms an intracellular nitrogen-fixing symbiosis with the angiosperm Gunnera. In symbiosis the cyanobacterium is enclosed in darkness and receives carbon from the plant in an unknown form. Out of five putative plant carbohydrate sources tested in vitro, fructose and glucose were found to support nitrogen fixation in darkness. The other three dextrin, sucrose and Gunnera sp. mucilage could not induce nitrogenase activity in darkness. The stimulatory effect by fructose was also observed in illuminated samples. After four weeks incubation in darkness, nitrogenase was still active in cultures when fructose was added and multiple thick-walled nitrogen-fixing cells (heterocysts) were observed, and chlorophyll levels unchanged. The expression as shown by Northern blot analysis revealed that fructose influenced the gene expression of hetR, a gene necessary for heterocyst formation, in darkness. Fructose and glucose may therefore be the carbohydrates supplied by the host plant to induce heterocyst differentiation and nitrogen fixation in the cyanobiont Nostoc PCC 9229.

  • 7.
    Wouters, Johanna
    et al.
    Södertörn University, School of Life Sciences, Environmental science.
    Janson, Sven
    Södertörn University, School of Life Sciences, Environmental science.
    Luskova, Vera
    Olsén, K. Håkan
    Södertörn University, School of Life Sciences, Environmental science. Södertörn University, School of Life Sciences, Biology.
    Molecular identification of hybrids of the invasive gibel carp Carassius auratus gibelio and crucian carp Carassius carassius in Swedish waters2012In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 80, no 7, p. 2595-2604Article in journal (Refereed)
    Abstract [en]

    Both mitochondrial DNA sequence and two nuclear microsatellite markers were used to confirm the identity of the first record of Carassius auratus gibelio in the western (Swedish) Baltic Sea region. A total of 49 fishes were analysed, where 22 were from three Swedish sites connected to the Baltic Sea. The D-loop mitochondrial DNA sequences showed that 16 of 22 Swedish fishes were related to C. a. gibelio. The phylogenetic analysis of these sequences showed that these fish are probably not native, but represent different lineages of C. a. gibelio from China, Japan and Russia. All except three of these 16 fishes had microsatellite alleles suggesting hybridization with Carassius carassius. These findings suggest that a cryptic invasion of C. a. gibelio might be in progress.

  • 8.
    Wouters, Johanna
    et al.
    Södertörn University, School of Life Sciences, Environmental science.
    Janson, Sven
    Södertörn University, School of Life Sciences, Environmental science.
    Olsén, K. Håkan
    Södertörn University, School of Life Sciences, Environmental science. Södertörn University, School of Life Sciences, Biology.
    Why didn’t we notice them earlier? The invasive fish Carassius gibelio(gibel carp) identified by genetic methods in Swedish waters.2011In: 7th International Conference on Marine Bioinvasions: Abstract Book, 2011, p. 162-Conference paper (Other academic)
  • 9.
    Wouters, Johanna
    et al.
    Department of Natural Sciences, University of Kalmar.
    Raven, John A.
    University of Dundee.
    Minnhagen, Susanna
    Department of Natural Sciences, University of Kalmar.
    Janson, Sven
    Department of Natural Sciences, University of Kalmar.
    The luggage hypothesis: Comparisons of two phototrophic hosts with nitrogen-fixing cyanobacteria and implications for analogous life strategies for kleptoplastids/secondary symbiosis in dinoflagellates2009In: Symbiosis, ISSN 0334-5114, E-ISSN 1878-7665, Vol. 49, no 2, p. 61-70Article, review/survey (Refereed)
    Abstract [en]

    Nostoc and Richelia belong to a group of heterocystous cyanobacteria and are unique within this group in forming intracellular symbioses with phototrophic hosts, the angiosperm Gunnera and the diatoms (algae) Rhizosolenia and Hemiaulus, respectively. The function of the cyanobiont is similar in the symbioses, namely providing fixed atmospheric nitrogen to their hosts; also the cyanobionts are contained in a host compartment, the symbiosome. The evolutionary timescale for the cyanobiont-endosymbiosis formation is in both instances about a parts per thousand 90 Ma. However, the potentials for further co-evolution of host and microsymbiont, are different. Nostoc is regarded as preyed upon by its host, while in the Richelia-Rhizosolenia symbiosis example the evolution towards a new type of permanent organelle is possible. It is proposed that symbiosis is ruled by divergent host strategies. In the case of Richelia-Rhizosolenia the evolution of a permanent symbiosis is linked to diatom hosts needing to carry the cyanobiont permanently, as it is not available free-living in the oceans. However, in the case of Nostoc/Gunnera, the host exploits an abundant cyanobacterial species. A model where the relative abundance of microsymbionts determines the nature of the symbiosis comes into view: If environmental ratios of host/microsymbiont are so that hosts are the dominating party, then the host has to carry the microsymbiont as luggage (vertical transmission). Likewise, if the ratio of microsymbiont is higher than host, than the host will prey on the microsymbiont (horizontal transmission). The article also discusses the retention of secondary plastids in dinoflagellates. We show that dinoflagellates are organisms that exemplify both types of strategies that is either preying or harbouring a permanent organelle. The difference from the cyanobacterial example is that only parts of the eukaryotic microsymbionts are kept, usually only the plastid. We emphasize that the dinoflagellates can obtain their plastids from various different organisms. The luggage theory offers an explanation to why some dinoflagellate species contain kleptoplastids, while others have permanent, secondary plastids and some have tertiary plastids.

1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • harvard-anglia-ruskin-university
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf