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  • 1.
    Andersson, Gunnar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Comparative Physiology.
    Differentiation and Pathogenicity within the Saprolegniaceae: Studies on Physiology and Gene Expression Patterns in Saprolegnia parasitica and Aphanomyces astaci2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Saprolegnia parasitica and Aphanomyces astaci are parasitic water moulds belonging to the Oomycetes. Despite their importance as parasites they are very little studied at the molecular level and the work described in this thesis was aimed at increasing the molecular knowledge of these organisms by cloning and characterising genes of potential importance for reproduction and pathogenicity.

    Stage-specific transcripts from Saprolegnia parasitica were isolated by differential display RT-PCR. One of the markers, puf1 encodes a putative mRNA binding protein which may be involved in post-transcriptional regulation of gene expression. S. parasitica puf1 is expressed exclusively in spore cysts that have not been determined for germination or repeated zoospore emergence indicating that the cyst stage has two phases, of about equal duration, which are physiologically and transcriptionally distinct. A similar expression pattern is observed in Aphanomyces spp. with different regulation of spore development and in the transcript is detected in both primary and secondary cysts.

    A putative chitinase AaChi1, was cloned from the crayfish plague fungus, Aphanomyces astaci. Analysis of chitinase activity and AaChi1 expression showed that chitinase in A. astaci is constitutively expressed in growing and sporulating mycelia, but absent in zoospores, a pattern which reflects the infectious life cycle of A. astaci. This expression pattern is conserved between the four known genotypes of A. astaci, in contrast to saprophytic and fish-pathogenic Aphanomyces spp.

    Genetic and physiological analysis were conducted on five strains of Aphanomyces, isolated from suspected outbreaks of crayfish plague in Spain and Italy. The strains are not virulent against freshwater crayfish, and RAPD PCR and ITS sequence analysis show that they are unrelated to the crayfish plague fungus, A. astaci.

    List of papers
    1. Pumilio homologue from Saprolegnia parasitica specifically expressed in undifferentiated spore cysts
    Open this publication in new window or tab >>Pumilio homologue from Saprolegnia parasitica specifically expressed in undifferentiated spore cysts
    2002 In: Eukaryotic Cell, Vol. 1, no 1Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-89574 (URN)
    Available from: 2001-12-20 Created: 2001-12-20Bibliographically approved
    2. Comparison of pufI expression in Aphanomyces spp. with different regulation of germination
    Open this publication in new window or tab >>Comparison of pufI expression in Aphanomyces spp. with different regulation of germination
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-89575 (URN)
    Available from: 2001-12-20 Created: 2001-12-20 Last updated: 2010-01-13Bibliographically approved
    3. Analysis of chitinase expression in the crayfish plague fungus, Aphanomyces astaci
    Open this publication in new window or tab >>Analysis of chitinase expression in the crayfish plague fungus, Aphanomyces astaci
    Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-89576 (URN)
    Available from: 2001-12-20 Created: 2001-12-20Bibliographically approved
    4. Physiological and Genetic Characterisation of some Aphanomyces Strains Isolated from Freshwater Crayfish
    Open this publication in new window or tab >>Physiological and Genetic Characterisation of some Aphanomyces Strains Isolated from Freshwater Crayfish
    Show others...
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-89577 (URN)
    Available from: 2001-12-20 Created: 2001-12-20 Last updated: 2010-01-13Bibliographically approved
  • 2.
    Andersson, M. G.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Comparative Physiology.
    Cerenius, L.
    Analysis of chitinase expression in the crayfish plague fungus, Aphanomyces astaciArticle in journal (Refereed)
  • 3.
    Andersson, M. G.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Comparative Physiology.
    Cerenius, L.
    Comparison of pufI expression in Aphanomyces spp. with different regulation of germinationManuscript (Other academic)
  • 4.
    Andersson, M. G.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Comparative Physiology.
    Cerenius, L.
    Pumilio homologue from Saprolegnia parasitica specifically expressed in undifferentiated spore cysts2002In: Eukaryotic Cell, Vol. 1, no 1Article in journal (Refereed)
  • 5.
    Bangyeekhun, Eakaphun
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Comparative Physiology.
    Parasite on Crayfish: Characterisation of Their Pathogenesis, Host Interactions and Diversity2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The crayfish plague refractory crayfish, Pacifastacus leniusculus, which can harbour the fungal parasite within melanotic sheath, are found to constitutively express the gene encoding for prophenoloxidase (proPO) after mimicking parasite attack. In contrast, the susceptible crayfish, Astacus astacus, responds to the parasite by increased levels of proPO transcript, particularly in the semigranular haemocytes. The upregulation of proPO could confer a temporary resistance towards the fungal infection, suggesting that additional factors are involved in maintaining the balance between host and parasite. The resistant crayfish may have adapted to the parasite by increasing the transcript level of immune genes. The parasite can be considered as a symbiont since it does not harm the host rather than it activates the immune gene and possibly preventing other pathogens to become established.

    Two serine proteinase genes encoding a subtilisin-like (AaSP1) and a trypsin (AaSP2) enzyme were isolated from the crayfish plague fungus, Aphanomyces astaci. These proteinases are prepropeptides and generate mature proteins of 39 kDa and 29 kDa, respectively. Characterisation of AaSP1 suggests that the enzyme may be involved in intracellular control mechanisms rather than playing a role in pathogenesis. The AaSP2 transcript was not controlled by catabolic repression, but was induced by crayfish plasma, implying a role in pathogenesis toward the crayfish host.

    Physiology and genetics of five Aphanomyces strains, which were isolated from moribund crayfish, were characterised with regard to their pathogen diversity. These strains are not virulent against crayfish. Some physiological properties of these strains differed from A. astaci, such as growth rate, germination and production of chitinase. Genetic analysis clearly indicated that they are not related to A. astaci and their name are proposed to be Aphanomyces repetans.

    The crayfish P. leniusculus was found to be susceptible to white spot syndrome virus infection. The virus has a significant effect to the population of crayfish haemocyte. The number and proportion of granular cell from virus-infected crayfish were higher than in controls, indicating granular cells are more resistant to and may interact by some means with the virus.

    Two morphotypes of the crayfish parasite Psorospermium haeckeli obtained from different crayfish hosts of different geographical origin were analysed for ribosomal ITS DNA in order to compare their genetic diversity. The sequence difference between them was found largely in ITS 1 and ITS 2 regions, which was variable in length and showed 66% and 58% sequence similarity. Thus, different morphotypes of P. haeckeli are genetically diverse.

  • 6.
    Lin, Xionghui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Comparative Physiology.
    Novotny, Marian
    Department of Cell Biology, Faculty of Natural Sciences, Charles University in Prague, Vinicna 7, Praha, 12843, Czech Republic.
    Söderhäll, Kenneth
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Comparative Physiology.
    Söderhäll, Irene
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Comparative Physiology.
    Invertebrate astakines - regulators of differentiation in hematopoietic tissuesManuscript (preprint) (Other academic)
    Abstract [en]

    Hematopoiesis is the process by which hemocytes mature and subsequently enter the circulation. Vertebrate prokineticins are known to take part in this process, as are the invertebrate prokineticin domain proteins, astakines. In Pacifastacus leniusculus astakine 1 is essential for the release of new hemocytes into the open circulatory system of these animals. In addition to astakine 1 we have now cloned a homologue of astakine 1 with an insert of 13 amino acids, named astakine 2. Common to both crustacean astakines is the lack of the N-terminal AVIT amino acids present in vertebrate PKs, and hence receptor binding differs from that of vertebrate PKs. Now we have found astakine-like sequences in 19 different invertebrate species and the sequences show that some motifs are conserved among invertebrate groups.

    Previously we showed that astakine 1 is directly involved in hematopoiesis and now we show that astakine 1 and astakine 2 have different roles in hemocyte lineage differentiation and that astakine 1 specifically induce differentiation along the semigranular cell lineage. Further we discuss the impact of the putative structure of different astakines in comparison with the vertebrate prokineticins.

     

     

     

     

     

     

  • 7.
    Royo, F.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Comparative Physiology.
    Andersson, M. G.
    Bangyeekhun, E.
    Cerenius, L.
    Múzquiz, J. L.
    Söderhäll, K.
    Physiological and Genetic Characterisation of some Aphanomyces Strains Isolated from Freshwater CrayfishManuscript (Other academic)
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