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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 224 (2003), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In studies of symbiotic efficiency it is of great importance to identify and separate individual Frankia strains from a nodule. Therefore, a new laser-based micromanipulation technique has been developed in which individual vesicles from root nodules of two Frankia–Alnus symbioses have been successfully cut loose and separated from clusters of vesicles in sterile conditions under light microscopy using a laser scalpel and optical tweezers. Vesicles from the Alnus incana–Frankia AvCI1 symbiosis were successfully isolated and grown in culture using this technique. The DNA from both Frankia sources was amplified by polymerase chain reaction (PCR). The work shows that a combination of laser-based manipulation techniques and PCR can be used for the separation and study of individual vesicles. This novel laser-based micromanipulation technique opens up various new possibilities, for instance, to study whether several Frankia strains can grow simultaneously in the same root nodule.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 236 (2004), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The ability to evolve hydrogen using methyl viologen as an electron donor was assayed in the nitrogen-fixing actinomycetes Frankia sp. R43 and Frankia sp. KB5. To further examine the nature of hydrogen-evolving enzymes that may be present in these organisms immunological studies were performed. Under anaerobic conditions (both nitrogen-limiting and nitrogen-containing) Frankia sp. R43 but not Frankia sp. KB5 evolved hydrogen, which was not linked to NAD-reducing activity. Immunological analysis of total protein from Frankia sp. R43 and Frankia sp. KB5 using an antiserum raised against Ralstonia eutropha HoxF, recognized an antigen in Frankia sp. R43 but not in Frankia sp. KB5. Immunogold labeling using antibodies raised against the R. eutropha HoxH recognized sites in both hyphae and vesicles of Frankia sp. R43, but not in Frankia sp. KB5. Based on these physiological and immunological findings, we conclude that Frankia sp. R43 has a hydrogen-evolving hydrogenase.
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 419 (2002), S. 917-920 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Biological nitrogen (N) fixation is the primary source of N within natural ecosystems, yet the origin of boreal forest N has remained elusive. The boreal forests of Eurasia and North America lack any significant, widespread symbiotic N-fixing plants. With the exception of scattered stands of ...
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 93 (1992), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Free-living N2-fixing Frankia strains isolated from Casuarina sp. were investigated for genomic polymorphism. We used six 10-mer oligonucleotides as single arbitrary primers (AP) for the polymerase chain reaction (PCR) in order to amplify random DNA fragments in the genome of free-living Frankia strains. Agarose-gels of the amplified genomic DNA revealed that two of the six arbitrary primers showed polymorphism in the eight different Frankia genomes. Analysis of the AP-PCR products showed 9 polymorphic bands ranging from 4.1–0.60 kb. We conclude that single arbitrary primers can be used to amplify genomic DNA, and that polymorphism can be detected between the amplification products of the different Frankia genomes.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 75 (1989), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Occurrence and activity of the hydrogen uptake enzyme were studied in root nodule homogenates made from plants of Alnus incana (L.) Moench collected from field sites in the northern part of Sweden. Nitrogenase (EC 1.7.99.2) activity (estimated by acetylene reduction) and hydrogen evolution were studied in excised nodules. All Frankia sources showed acetylene reduction activity, and possessed a hydrogen uptake system. Hydrogen uptake in nodule homogenates from the Frankia sources measured at 23.8 μM H2 ranged from 0.04 to 5.0 μmol H2 (g fresh weight nodule)−1 h−1. The H2 uptake capacity of nodule homogenates from one of the Frankia sources was almost 8 times higher than the hydrogen evolution from nitrogenase, both expressed on a nodule fresh weight basis. Frankia sources from field sites 6 and 11 showed Km for H2 of 13.0 and 23.6 μM H2, respectively. This indicates similarities in the hydrogen uptake enzymes in the two Frankia sources. It is concluded that hydrogen uptake is a common characteristic in Frankia.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 70 (1987), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hydrogen metabolism was studied in three Casuarina species, C, equisetifolia Forst., C. glauca Sieb. ex. Spreng. and C. obesa Miq., either inoculated with the pure Frankia culture HFP CcI3 or inoculated with a crushed nodule inoculum made from C. glauca nodules. Nitrogenase (EC 1.7.99.2) activity and hydrogen evolution was measured on intact plants, while hydrogen uptake was measured on excised nodules and in nodule homogenates.Nitrogenase activity was highest in C. glauca inoculated with C. glauca nodules, while no hydrogen evolution was detected. Hydrogen evolution was highest in the symbiosis between C. equisetifolia and HFP CcI3, but the nitrogenase activity showed intermediate values compared to the other symbioses. Measured at a concentration of 93 μM H2, H2 uptake was highest in C. glauca inoculated with the C. glauca inoculum. H2 uptake activity in homogenates was 83% of the intact nodule rate. With phenazinemethosulfate as the electron acceptor, H2 uptake by nodule homogenates showed typical Michaelis-Menten kinetics with a Km of 21.3 μM for H2.The data presented here indicate a host plant effect on the endobiont which alters the hydrogen metabolism.
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  • 7
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Three different strains of Frankia, the pure cultures AvcI1 and CpI1 and a local strain (crushed nodule inoculum), were compared in symbiosis with one clone of Alnus incana (L.) Moench. Hydrogen metabolism, nitrogenase (EC 1.7.99.2) activity and relative efficiency of nitrogenase were studied as well as growth and nitrogen content of the plants. The local Frankia strain showed no measurable hydrogen uptake but high H2-evolution. No H2-evolution was detected in Frankia AvcI1 because of its hydrogenase activity. CpI1 also had hydrogenase, although only a very small H2-evolution was detected at the end of the growth period. Hydrogenase activity was detected both in pure cultures and nodule homogenates of CpI1 and AvcI1. Growth, biomass production and nitrogen content were highest in alders inoculated with Frankia AvcI1 while the lowest values were found for alders living in symbiosis with the local Frankia strain. The presence of hydrogenase in Frankia seemed to be benefical for growth and biomass production in the alders. However, the strains also differed with respect to spore formation. The local strain, but not AvcI1 and CpI1, formed spores in the root nodules.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 70 (1987), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Actinorhizal nodules do not usually evolve H2 due to the action of an uptake hydrogenase. We have found that nodules of several Frankia symbioses evolved large amounts of H2 gas when returned to air following exposure to 10 kPa C2HT2 during an acetylene reduction assay. Increased H2 evolution in air persisted for several days when intact root systems of Alnus incana (L.) Moench (inoculated with Frankia UGL 011101) were treated with 10 kPa C.H2 for 1 h. Full recovery of uptake hydrogenase activity required 4 to 8 days. Studies with crude homogenates of nodules of the same plants showed that hydrogenase (measured amperometrically with phenazine metho-sulfate as electron acceptor) was directly affected, since activity in treated nodules was only 10% of that in untreated nodules. A survey of actinorhizal symbioses revealed variation in the effect of an acetylene reduction assay on hydrogen metabolism. Nodules of three species, including Alnus rubra Bong, inoculated with Frankia HFPArD. showed complete inactivation of hydrogenase. H2 evolution in air was 25% of the C2H2 reduction rate and H, evolution in Ar/O2 was equal to the QH2 reduction rate. Two symbioses, Ceanothus americanus L. (soil inoculant) and Batista glomerata Baill. (soil inoculant) showed no change following an acetylene reduction assay. A third group of symbioses showed an intermediate response.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 70 (1990), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Five free-living Frankia strains isolated from Casuarina were investigated for occurrence of hydrogenase activity. Nitrogenase activity (acetylene reduction) and hydrogen evolution were also evaluated. Acetylene reduction was recorded in all Frankia strains. None of the Frankia strains had any hydrogenase activity when grown on nickel-depleted medium and they released hydrogen in atmospheric air. After addition of nickel to the medium, the Frankia strains were shown to possess an active hydrogenase, which resulted in hydrogen uptake but no hydrogen evolution. The hydrogenase activity in Frankia strain KB5 increased from zero to 3.86 μmol H2 (mg protein)−1 h−1 after addition of up to 1.0 μM Ni. It is likely that the hydrogenase activity could be enhanced even more as a response on further addition of Ni. It is indicated in this study that absence of hydrogenase activity in free-living Frankia isolated from Casuarina spp. is due to nickel deficiency. Frankia living in symbiosis with Casuarina spp. show hydrogenase activity. Therefore, the results also indicate that the hydrogenase to some extent is regulated by the host plant and/or that the host plant supplies the symbiotic microorganism with nickel. Moreover, the result shows that this Frankia is somewhat different from Frankia isolated from Alnus incana and Comptonia peregrina., i.e., Frankia isolated from A. incana and C. peregrina showed a small hydrogen uptake activity even without addition of nickel.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 60 (1989), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The free-living Frankia strain CpI1 cultured under nitrogen-fixing and non-nitrogen-fixing conditions was investigated for occurrence of hydrogenase protein by Western blots. Transmission electron microscopy and immunocytological labelling were used to study the distribution of hydrogenase in the Frankia strain.Western immunoblots revealed that a 72-kDa protein in the Frankia strain CpI1 was immunologically related to the large subunit of a dimeric hydrogenase purified from Alcaligenes latus. Immunolocalization showed that the hydrogenase protein is located both in vesicles and hyphae in Frankia strain CpI1 grown in a nitrogen-free medium. Earlier reports that nitrogenase is localized in the vesicles [1,2], together with this finding, point out a possible role for hydrogenase in increasing relative efficiency of nitrogen fixation. In CpI1 grown in media containing nitrogen (lacking vesicles), the enzyme was evenly distributed in the hyphae. The impact of this result has to be further analysed.
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