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  • 1. DeLuca, T H
    et al.
    Zackrisson, O
    Nilsson, M C
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Quantifying nitrogen-fixation in feather moss carpets of boreal forests2002In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 419, no 6910, p. 917-920Article in journal (Refereed)
    Abstract [en]

    Biological nitrogen (N) fixation is the primary source of N within natural ecosystems(1), 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(1-6). With the exception of scattered stands of alder in early primary successional forests(7), N-fixation in boreal forests is considered to be extremely limited. Nitrogen-fixation in northern European boreal forests has been estimated(2) at only 0.5 kg Nha(-1) yr(-1); however, organic N is accumulated in these ecosystems at a rate of 3 kg N ha(-1) yr(-1) (ref. 8). Our limited understanding of the origin of boreal N is unacceptable given the extent of the boreal forest region, but predictable given our imperfect knowledge of N-fixation(1,9). Herein we report on a N-fixing symbiosis between a cyanobacterium (Nostoc sp.) and the ubiquitous feather moss, Pleurozium schreberi (Bird) Mitt. that alone fixes between 1.5 and 2.0 kg N ha(-1) yr(-1) in mid- to late-successional forests of northern Scandinavia and Finland. Previous efforts have probably underestimated N-fixation potential in boreal forests.

  • 2. DeLuca, Thomas H
    et al.
    Zackrisson, Olle
    Gentili, Francesco
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Nilsson, Marie-Charlotte
    Ecosystem controls on nitrogen fixation in boreal feather moss communities.2007In: Oecologia, ISSN 0029-8549, Vol. 152, no 1, p. 121-30Article in journal (Refereed)
    Abstract [en]

    N fixation in feather moss carpets is maximized in late secondary successional boreal forests; however, there is limited understanding of the ecosystem factors that drive cyanobacterial N fixation in feather mosses with successional stage. We conducted a reciprocal transplant experiment to assess factors in both early and late succession that control N fixation in feather moss carpets dominated by Pleurozium schreberi. In 2003, intact microplots of moss carpets (30 cm × 30 cm × 10–20 cm deep) were excavated from three early secondary successional (41–101 years since last fire) forest sites and either replanted within the same stand or transplanted into one of three late successional (241–356 years since last fire) forest sites and the transverse was done for late successional layers of moss. Moss plots were monitored for changes in N-fixation rates by acetylene reduction (June 2003–September 2005) and changes in the presence of cyanobacteria on moss shoots by microscopy (2004). Forest nutrient status was measured using ionic resin capsules buried in the humus layer. Late successional forests exhibit high rates of N fixation and consistently high numbers of cyanobacteria on moss shoots, but low levels of available N. Conversely, early successional forests have higher N availability and have low rates of N fixation and limited presence of cyanobacteria on moss shoots. Transplantation of moss carpets resulted in a significant shift in presence and activity of cyanobacteria 1 year after initiation of the experiment responding to N fertility differences in early versus late successional forests.

  • 3.
    Gentili, Francesco
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Nilsson, Marie-Charlotte
    Zackrisson, Olle
    DeLuca, Thomas H
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Physiological and molecular diversity of feather moss associative N2-fixing cyanobacteria.2005In: Journal of Experimental Botany, ISSN 0022-0957, Vol. 56, no 422, p. 3121-7Article in journal (Refereed)
    Abstract [en]

    Cyanobacteria colonizing the feather moss Pleurozium schreberi were isolated from moss samples collected in northern Sweden and subjected to physiological and molecular characterization. Morphological studies of isolated and moss-associated cyanobacteria were carried out by light microscopy. Molecular tools were used for cyanobacteria identification, and a reconstitution experiment of the association between non-associative mosses and cyanobacteria was conducted. The influence of temperature on N2 fixation in the different cyanobacterial isolates and the influence of light and temperature on N2-fixation rates in the moss were studied using the acetylene reduction assay. Two different cyanobacteria were effectively isolated from P. schreberi: Nostoc sp. and Calothrix sp. A third genus, Stigonema sp. was identified by microscopy, but could not be isolated. The Nostoc sp. was found to fix N2 at lower temperatures than Calothrix sp. Nostoc sp. and Stigonema sp. were the predominant cyanobacteria colonizing the moss. The attempt to reconstitute the association between the moss and cyanobacteria was successful. The two isolated genera of cyanobacteria in feather moss samples collected in northern Sweden differ in their temperature optima, which may have important ecological implications.

  • 4.
    Holmgren, Marie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Identification of white-rot and soft-rot fungi increasing ethanol production from spent sulfite liquor in co-culture with Saccharomyces cerevisiae2008In: Journal of Applied Microbiology, ISSN 1364-5072, E-ISSN 1365-2672, Vol. 105, no 1, p. 134-140Article in journal (Refereed)
    Abstract [en]

    Aim: To identify fungi that are capable of increasing ethanol production from lignocellulose in spent sulfite liquor.

    Methods and Results: In a batch fermentation study, the fungal mix could produce 24·61 g l−1 ethanol using spent sulfite liquor as substrate. The fungal mix grew well on glucose, xylose, hemicellulose and cellulose. In addition, we were able to identify the fungal mix by use of PCR-amplification of DNA and sequencing, and they were identified as Chalara parvispora and Trametes hirsuta/T. versicolor. In a reconstitution study, the identified fungi were shown to produce equal amount of ethanol as the fungal mix. We were also able to show that C. parvispora could produce ethanol from xylose.

    Conclusion: The present study has shown that ethanol production from biomass can be increased by use of C. parvispora and T. versicolor when compared with fermentation using only S. cerevisiae.

    Significance and Impact of the Study: The study shows that refining biomass by ethanol production from spent sulfite liquor, a lignocellulose material, can be increased by adding C. parvispora and T. versicolor, and it is thus of great potential economical impact.

  • 5. HUSSDANELL, K
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    NITROGENASE ACTIVITY IN RESPONSE TO DARKENING AND DEFOLIATION OF ALNUS-INCANA1985In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 36, no 170, p. 1352-1358Article in journal (Refereed)
  • 6.
    HUSSDANELL, K
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    NITROGENASE ACTIVITY IN RESPONSE TO RESTRICTED SHOOT GROWTH IN ALNUS-INCANA1983In: Canadian Journal of Botany, ISSN 0008-4026, E-ISSN 1480-3305, Vol. 61, no 11, p. 2949-2955Article in journal (Refereed)
  • 7.
    HUSSDANELL, K
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    FLOWERELLIS, A
    SJOSTROM, M
    AMMONIUM EFFECTS ON FUNCTION AND STRUCTURE OF NITROGEN-FIXING ROOT-NODULES OF ALNUS-INCANA (L) MOENCH1982In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 156, no 4, p. 332-340Article in journal (Refereed)
  • 8.
    Kosawang, Chatchai
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Kudahettige, Rasika Lasanthi
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Resman, Lars
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Hydrogen yield from a hydrogenase in Frankia R43 at different levels of the carbon source propionate2012In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 95, no Supplement, p. S365-S368Article in journal (Refereed)
    Abstract [en]

    Fermentative hydrogen yield was investigated in the Frankia strain R43, which was grown in different amounts of the carbon source propionate. In relation to hydrogen yield, the hydrogenase enzyme was characterized by use of Western blot. A bioreactor study revealed a 10-fold increase in growth within 50 h. The study showed that there is an active anaerobic hydrogen production in Frankia R43 and that this hydrogenase is immunologically related to the subunit HoxU of Ralstonia eutropha.

  • 9.
    Kudahettige, Rasika L.
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Holmgren, Marie
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Imerzeel, Peter
    Department of Biochemistry, University of Lund, Getingevägen 60, 22241 Lund, Sweden.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Characterization of bioethanol production from hexoses and xylose by the white rot fungus trametes versicolor2012In: Bioenergy Research, ISSN 1939-1234, E-ISSN 1939-1242, Vol. 5, no 2, p. 277-285Article in journal (Refereed)
    Abstract [en]

    Bioethanol production by white rot fungus (Trametes versicolor), identified from fungal mixture in naturally decomposing wood samples, from hexoses and xylose was characterized. Results showed that T. versicolor can grow in culture, under hypoxic conditions, with various mixtures of hexoses and xylose and only xylose. Xylose was efficiently fermented to ethanol in media containing mixtures of hexoses and xylose, such as MBMC and G11XY11 media (Table 1), yielding ethanol concentrations of 20.0 and 9.02 g/l, respectively, after 354 h of hypoxic culture. Very strong correlations were found between ethanolic fermentation (alcohol dehydrogenase activity and ethanol production), sugar consumption and xylose catabolism (xylose reductase, xylitol dehydrogenase and xylulokinase activities) after 354 h in culture in MBMC medium. In a medium (G11XY11) containing a 1:1 glucose/xylose ratio, fermentation efficiency of total sugars into ethanol was 80% after 354 h.

  • 10. Leitz, G
    et al.
    Lundberg, C
    Fallman, E
    Axner, O
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Laser-based micromanipulation for separation and identification of individual Frankia vesicles2003In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 224, no 1, p. 97-100Article in journal (Refereed)
    Abstract [en]

    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 AvCIl 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. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

  • 11.
    Leul, Melakeselam
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Mohapatra, Anasuya
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Biodiversity of Hydrogenases in Frankia2005In: Current Microbiology, ISSN 0343-8651, E-ISSN 1432-0991, Vol. 50, no 1, p. 17-23Article in journal (Refereed)
    Abstract [en]

    Eighteen Frankia strains originally isolated from nine different host plants were used to study the biodiversity of hydrogenase in Frankia. In the physiological analysis, the activities of uptake hydrogenase and bidirectional hydrogenase were performed by monitoring the oxidation of hydrogen after supplying the cells with 1% hydrogen and the evolution of hydrogen using methyl viologen as an electron donor, respectively. These analyses were supported with a study of the immunological relationship between Frankia hydrogenase and other different known hydrogenases from other microorganisms. Uptake hydrogenase activity was recorded from all the Frankia strains investigated. A methyl-viologen-mediated hydrogen evolution was recorded from only four Frankia strains irrespective of the source of Frankia. From the immunological and physiological studies, we here report that there are at least three types of hydrogenases in Frankia: Ni-Fe uptake hydrogenase, hydrogen-evolving hydrogenase, and [Fe]-hydrogenase. An immunogold localization study, by cryosection technique, of the effect of nickel on the intercellular distribution of hydrogenase proteins in Frankia indicated that nickel affects the transfer of hydrogenase proteins into the membrane.

  • 12.
    Leul, Melakeselam
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Normand, Philippe
    Université de Lyon, Lyon, France .
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    The organization, regulation and phylogeny of uptake hydrogenase genes in Frankia2007In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 130, no 3, p. 464-470Article in journal (Refereed)
    Abstract [en]

    Frankia alni ACN14a, Frankia sp. CcI3 and Frankia sp. EAN1pec, which have different host specificity and geographical distribution, have two uptake hydrogenase syntons in their genome: hydrogenase synton#1 and hydrogenase synton#2. The organization of hydrogenase genes on these syntons also varies. Phylogenetic analysis of the structural genes of these syntons showed that they were significantly divergent and that hydrogenase synton#1 subunits of these Frankia strains were probably ancestral among the actinobacteria. Hydrogenase gene duplication might have occurred long before emergence of the three Frankia lineages. The structural subunits of hydrogenase HupS2 and HupL2 (synton#2) of F. alni ACN14a and Frankia sp. CcI3, which belong to phylogenetic Frankia cluster 1, were grouped closely together but away from Frankia sp. EAN1pec, which belongs to Frankia cluster 3. Phylogenetic analysis showed the occurrence of lateral transfer of hupL2 in Frankia sp. EAN1pec to or from Geobacter sulfurreducens. The transcript levels of hupS1 and hupL1 relative to hupS2 and hupL2 were higher in F. alni ACN14a grown under free-living conditions. Under symbiotic conditions, transcript levels of hupS2 and hupL2 were higher than those of hupS1 and hupL1. Hydrogenase subunits of synton#1 are more expressed under free-living conditions, whereas those of synton#2 are mainly involved in symbiotic interactions.

  • 13.
    Leul, Melakeselam
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Normand, Philippe
    Microbial Ecology, UMR 5557, CNRS, University Lyon 1, Villeurbanne, France.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    The phylogeny of uptake hydrogenases in Frankia2009In: International Microbiology, ISSN 1139-6709, E-ISSN 1618-1905, Vol. 12, no 1, p. 23-28Article in journal (Refereed)
    Abstract [en]

    Uptake hydrogenase is an enzyme that is beneficial for nitrogen fixation in bacteria. Recent studies have shown that Frankia sp. has two sets of uptake hydrogenase genes, organized in synton 1 and synton 2. In the present study, phylogenetic analysis of the structural subunits of hydrogenase syntons 1 and 2 showed a distinct clustering pattern between the proteins of Frankia strains that were isolated from different host plants and non-Frankia organisms. The structural subunits of hydrogenase synton 1 of Frankia sp. CpI1, Frankia alni ACN14a, and F. alni AvCI1 were grouped together while those of Frankia spp. CcI3, KB5, UGL140104, and UGL011102 formed another group. The structural subunits of hydrogenase synton 2 of F. alni ACN14a and Frankia spp. CcI3 and BCU110501 grouped together, but those of Frankia spp. KB5 and CpI1, F. alni ArI3, and F. alniAvCI1 comprised a separate group. The structural subunits of hydrogenase syntons 1 and 2 of Frankia sp. EAN1pec were more closely related to those of non-Frankia bacteria, i.e., Streptomyces avermitilis and Anaeromyxobacter sp., respectively, than to those of other Frankia strains, suggesting the occurrence of lateral gene transfer between these organisms. In addition, the accessory Hyp proteins of hydrogenase syntons 1 and 2 of F. alni ACN14a and Frankia sp. CcI3 were shown to be phylogenetically more related to each other than to those of Frankia EAN1pec.

  • 14. LINDBLAD, P
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    IMMUNOGOLD LOCALIZATION OF HYDROGENASE IN FREE-LIVING FRANKIA CPI11989In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 60, no 3, p. 311-315Article in journal (Refereed)
  • 15. LINDBLAD, P
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    OCCURRENCE AND LOCALIZATION OF AN UPTAKE HYDROGENASE IN THE FILAMENTOUS HETEROCYSTOUS CYANOBACTERIUM NOSTOC PCC-731021990In: Protoplasma, ISSN 0033-183X, E-ISSN 1615-6102, Vol. 159, no 1, p. 9-15Article in journal (Refereed)
    Abstract [en]

    Free-living nitrogen-fixing Nostoc PCC 73102, a filamentous heterocystous cyanobacterium originally isolated from coralloid roots of the cycad Macrozamia sp., were examined for the presence of an uptake hydrogenase (H-2ase) enzyme. In vivo and in vitro hydrogen uptake measurements were used to study activities and SDS-PAGE and Western immunoblots to reveal occurrence of the hydrogenase protein. Also, transmission electron microscopy and immunocytological labeling were used to study the cellular and subcellular distribution of H-2se in the Nostoc cells. In vivo measurements demonstrated an active uptake of hydrogen in both light and darkness. Light stimulated in vivo hydrogen uptake with approximately 100%, and this was further doubled by increasing the pH2, from 56 to 208-mu-M H-2. An in vitro hydrogen of 1.1-mu-mol H-2/mg (protein)/h was observed when using phenazinemethosulphate as e- -acceptor. Western immunoblots revealed that a polypeptide with a molecular weight of about 55 kDa was immunologically related to uptake H-2ase holoenzyme purified from Alcaligenes latus. Immunolocalization demonstrated that the H-2ase protein was located both in heterocysts and vegetative cells. A higher specific labeling was associated with the cytoplasmic membranes where the vegetative cells are in contact with each other and where they actually are dividing into two vegetative cells. Using the particle analysis of an image processor, approximately equal H-2ase-gold labeling per cell area was observed in the nitrogen-fixing heterocysts compared to the photosynthetic vegetative cells. This study also shows that there was no correlation between presence of phycoerythrin and uptake H-2ase activity.

  • 16. Mattsson, U
    et al.
    Johansson, L
    Sandstrom, G
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Frankia KB5 possesses a hydrogenase immunologically related to membrane-bound [NiFe]-hydrogenases2001In: Current Microbiology, ISSN 0343-8651, E-ISSN 1432-0991, Vol. 42, no 6, p. 438-441Article in journal (Refereed)
    Abstract [en]

    The immunological relationship of the hydrogenase in Frankia KB5 to hydrogenases in other microorganisms was investigated using antisera raised against holo-[NiFe]-hydrogenases isolated from Alcaligenes latus, Azotobacter vinelandii, Ralstonia eutropha, and the small and large hydrogenase subunits from Bradyrhizobium japonicum. The antisera raised against the A. latus, R. eutropha, and B. japonicum (large subunit) polypeptides were found to recognize two polypeptides, corresponding to the unprocessed and processed forms of the hydrogenase subunit in Frankia KB5. None of the antisera, including the antibodies produced against the small hydrogenase subunit isolated from B. japonicum, recognized any polypeptide related to the small hydrogenase subunit in Frankia KB5. An immunogold localization study of the intracellular distribution of hydrogenase in Frankia KB5, with the cryo-section technique, showed that labeling in the membrane of both hyphae and vesicles was positively correlated with hydrogenase activity.

  • 17. Mattsson, U
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Hydrogenase in Frankia KB5: Expression of and relation to nitrogenase2000In: Canadian journal of microbiology (Print), ISSN 0008-4166, E-ISSN 1480-3275, Vol. 46, no 12, p. 1091-1095Article in journal (Refereed)
    Abstract [en]

    The localization and expression of the hydrogenase in free-living Frankia KB5 was investigated immunologically and by monitoring activity, focusing on its relationships with nitrogenase and H-2. Immunological studies revealed that the large subunit of the hydrogenase in Frankia KB5 was modified post-translationally, and transferred into the membrane after processing. The large subunit was constitutively expressed and no correlation was found between hydrogenase activity and synthesis. Although H-2 was not needed for induction of hydrogenase synthesis, exogenously added H-2 triggered hydrogen uptake in medium containing nitrogen, i.e., in the hyphae. A correlation between nitrogenase activity and hydrogen uptake was found in cultures grown in media without nitrogen, but interestingly the two enzymes showed no co-regulation.

  • 18. Mattsson, U
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Nickel affects activity more than expression of hydrogenase protein in Frankia2002In: Current Microbiology, ISSN 0343-8651, E-ISSN 1432-0991, Vol. 44, no 2, p. 88-93Article in journal (Refereed)
    Abstract [en]

    The effects of nickel on hydrogen uptake and the post-translational processing of the large subunit of the hydrogenase protein in three Frankia strains (one isolated from an Alnus-Frankia symbiosis and two from Casuarina-Frankia associations) were investigated. All three strains responded to the addition of nickel with an increase in hydrogen uptake. Additional nickel did not affect nitrogenase activity, however evolved hydrogen was detected in Frankia KB5 in the absence of additional nickel, indicating that hydrogenase was not active. No increase in the processing rate of the hydrogenase large subunit was found with increasing nickel concentrations for any of the strains, indicating that the strategy for regulating hydrogenase in Frankia is different from that in other microorganisms.

  • 19.
    Mohapatra, Anasuya
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Leul, Melakeselam
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Mattsson, Ulrika
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    A hydrogen-evolving enzyme is present in Frankia sp. R432004In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 236, no 2, p. 235-240Article in journal (Refereed)
    Abstract [en]

    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.

  • 20.
    Mohapatra, Anasuya
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Leul, Melakeselam
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sandström, Gunnar
    Karolinska Institutet, Department of Laboratory Medicine, Division of Clinical Bacteriology, Karelinska University Hospital, Huddinge, Stockholm, Sweden.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Occurrence and characterisation of the hydrogen-evolving enzyme in Frankia sp.2006In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 31, no 11, p. 1445-1451Article in journal (Refereed)
    Abstract [en]

    An increase in hydrogen evolution from the hydrogen-evolving enzyme in the actinomycete Frankia was recorded in the presence of nickel. Immunogold localisation analysis of the intracellular distribution of hydrogenase proteins indicated that they were evenly distributed in the membranes and cytosol of both hyphae and vesicles. In addition, molecular characterisation of the hydrogen-evolving enzyme at the proteomic level, using two-dimensional gel electrophoresis combined with mass spectrometry, confirmed that the Frankia hydrogen-evolving enzyme is similar to the cyanobacterial bidirectional hydrogenase of Anabena siamensis.

  • 21. Normand, Philippe
    et al.
    Lapierre, Pascal
    Tisa, Louis S
    Gogarten, Johann Peter
    Alloisio, Nicole
    Bagnarol, Emilie
    Bassi, Carla A
    Berry, Alison M
    Bickhart, Derek M
    Choisne, Nathalie
    Couloux, Arnaud
    Cournoyer, Benoit
    Cruveiller, Stephane
    Daubin, Vincent
    Demange, Nadia
    Francino, Maria Pilar
    Goltsman, Eugene
    Huang, Ying
    Kopp, Olga R
    Labarre, Laurent
    Lapidus, Alla
    Lavire, Celine
    Marechal, Joelle
    Martinez, Michele
    Mastronunzio, Juliana E
    Mullin, Beth C
    Niemann, James
    Pujic, Pierre
    Rawnsley, Tania
    Rouy, Zoe
    Schenowitz, Chantal
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Tavares, Fernando
    Tomkins, Jeffrey P
    Vallenet, David
    Valverde, Claudio
    Wall, Luis G
    Wang, Ying
    Medigue, Claudine
    Benson, David R
    Genome characteristics of facultatively symbiotic Frankia sp. strains reflect host range and host plant biogeography.2007In: Genome Research, ISSN 1088-9051, Vol. 17, no 1, p. 7-15Article in journal (Refereed)
    Abstract [en]

    Soil bacteria that also form mutualistic symbioses in plants encounter two major levels of selection. One occurs during adaptation to and survival in soil, and the other occurs in concert with host plant speciation and adaptation. Actinobacteria from the genus Frankia are facultative symbionts that form N2-fixing root nodules on diverse and globally distributed angiosperms in the "actinorhizal" symbioses. Three closely related clades of Frankia sp. strains are recognized; members of each clade infect a subset of plants from among eight angiosperm families. We sequenced the genomes from three strains; their sizes varied from 5.43 Mbp for a narrow host range strain (Frankia sp. strain HFPCcI3) to 7.50 Mbp for a medium host range strain (Frankia alni strain ACN14a) to 9.04 Mbp for a broad host range strain (Frankia sp. strain EAN1pec.) This size divergence is the largest yet reported for such closely related soil bacteria (97.8%–98.9% identity of 16S rRNA genes). The extent of gene deletion, duplication, and acquisition is in concert with the biogeographic history of the symbioses and host plant speciation. Host plant isolation favored genome contraction, whereas host plant diversification favored genome expansion. The results support the idea that major genome expansions as well as reductions can occur in facultative symbiotic soil bacteria as they respond to new environments in the context of their symbioses.

  • 22.
    Richau, Kerstin H.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Kudahettige, R. L.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Pujic, P.
    Kudahettige, N. P.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Structural and gene expression analyses of uptake hydrogenases and other proteins involved in nitrogenase protection in Frankia2013In: Journal of Biosciences, ISSN 0250-5991, E-ISSN 0973-7138, Vol. 38, no 4, p. 703-712Article in journal (Refereed)
    Abstract [en]

    The actinorhizal bacterium Frankia expresses nitrogenase and can therefore convert molecular nitrogen into ammonia and the by-product hydrogen. However, nitrogenase is inhibited by oxygen. Consequently, Frankia and its actinorhizal hosts have developed various mechanisms for excluding oxygen from their nitrogen-containing compartments. These include the expression of oxygen-scavenging uptake hydrogenases, the formation of hopanoid-rich vesicles, enclosed by multi-layered hopanoid structures, the lignification of hyphal cell walls, and the production of haemoglobins in the symbiotic nodule. In this work, we analysed the expression and structure of the so-called uptake hydrogenase (Hup), which catalyses the in vivo dissociation of hydrogen to recycle the energy locked up in this 'waste' product. Two uptake hydrogenase syntons have been identified in Frankia: synton 1 is expressed under free-living conditions while synton 2 is expressed during symbiosis. We used qPCR to determine synton 1 hup gene expression in two Frankia strains under aerobic and anaerobic conditions. We also predicted the 3D structures of the Hup protein subunits based on multiple sequence alignments and remote homology modelling. Finally, we performed BLAST searches of genome and protein databases to identify genes that may contribute to the protection of nitrogenase against oxygen in the two Frankia strains. Our results show that in Frankia strain ACN14a, the expression patterns of the large (HupL1) and small (HupS1) uptake hydrogenase subunits depend on the abundance of oxygen in the external environment. Structural models of the membrane-bound hydrogenase subunits of ACN14a showed that both subunits resemble the structures of known [NiFe] hydrogenases (Volbeda et al. 1995), but contain fewer cysteine residues than the uptake hydrogenase of the Frankia DC12 and Eu1c strains. Moreover, we show that all of the investigated Frankia strains have two squalene hopane cyclase genes (shc1 and shc2). The only exceptions were CcI3 and the symbiont of Datisca glomerata, which possess shc1 but not shc2. Four truncated haemoglobin genes were identified in Frankia ACN14a and Eu1f, three in CcI3, two in EANpec1 and one in the Datisca glomerata symbiont (Dg).

  • 23. Santos, Catarina L
    et al.
    Vieira, João
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Normand, Philippe
    Moradas-Ferreira, Pedro
    Tavares, Fernando
    Modulation of Frankia alni ACN14a oxidative stress response: activity, expression and phylogeny of catalases2007In: Physiologia Plantarum, Vol. 130, p. 454-463Article in journal (Refereed)
    Abstract [en]

    The finding that an oxidative burst was a general phenomenon in the response of hosts challenged by various symbiotic or pathogenic microbes has stimulated increasing interest in investigating the enzymology of antioxidant protection in bacteria. The question of whether the antioxidant mechanisms have been a decisive evolutionary driving force for the nitrogen-fixing microsymbiont Frankia spp. is still open. In this study, Frankia alni strain ACN14a, which is a mid-range infective strain, was used as a model to explore the basal oxidative stress response in terms of enzymatic activity, relative expression and phylogeny. Non-denaturing polyacrylamide gels stained for catalatic activity revealed the presence of two monofunctional catalases KatA and KatB (EC number 1.11.1.6), which activity was shown to increase when the cells were challenged with the oxidants H2O2 and methyl viologen. Real-time RT-PCR targeting the two genes showed a consistent increase in the number of transcripts when the RNA was extracted from oxidative stress-induced cells. Comparison between the expression and the activity data suggests that posttranscriptional mechanisms might be involved in the regulation of catalases in F. alni. Furthermore, upstream of katA, a fur gene coding for a ferric uptake regulator was found, forming a gene pair that functionally resembles the conserved actinobacterial synton fur–katG, which contains a gene coding for a catalase–peroxidase. Phylogenetic analysis of the F. alni fur–katA synton suggests that this genomic organization was the result of genome reshuffling events.

  • 24.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    ACETYLENE-REDUCTION, H-2 EVOLUTION AND N-14(2) FIXATION IN THE ALNUS-INCANA-FRANKIA SYMBIOSIS1986In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 167, no 3, p. 382-386Article in journal (Refereed)
  • 25.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    NITROGEN AND CARBON UTILIZATION IN ALNUS-INCANA FIXING N-2 OR SUPPLIED WITH NO3 AT THE SAME RATE1986In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 37, no 179, p. 786-797Article in journal (Refereed)
  • 26.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    NITROGENASE ACTIVITY, HYDROGEN EVOLUTION AND BIOMASS PRODUCTION IN DIFFERENT CASUARINA SYMBIOSES1988In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 105, no 1, p. 33-40Article in journal (Refereed)
  • 27.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    OCCURRENCE AND ACTIVITY OF HYDROGENASE IN SYMBIOTIC FRANKIA FROM FIELD-COLLECTED ALNUS-INCANA1989In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 75, no 2, p. 304-308Article in journal (Refereed)
  • 28.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    SPECIFICITY AND EFFECTIVITY IN NODULATION BY FRANKIA ON SOUTHERN-HEMISPHERE ACTINORHIZA1995In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 125, no 2-3, p. 231-236Article in journal (Refereed)
    Abstract [en]

    Nodulation ability was tested for Frankia strains HFPCcI3 and EL1, and Frankia sources A.t. and G.a. from Allocasuarina torulosa and Gymnostoma australianum, respectively, on A. torulosa Mig., Casuarina cunninghamiana Mig., G. australianum L. Johnson and Elaeagnus triflora Roxb. It was shown that A. torulosa and C. cunninghamiana formed nodules only with the Frankia sources obtained from their own host plant, while E. triflora formed nodules with three of the four Frankia sources tested. All nodules formed were effectively fixing nitrogen. Specific nitrogenase activity was highest in E. triflora inoculated with the Frankia strain isolated from nodules of the same species. Identification of Frankia sources in the nodules was performed by use of PCR amplification of DNA with a random primer. PCR amplification of DNA isolated from nodules of G. australianum and E. triflora inoculated with Frankia strain EL1 revealed, when compared with DNA amplified from free living Frankia strain EL1, that there was only one Frankia strain causing the observed nodules.

  • 29.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    ATKINS, CA
    COMPOSITION OF AMINO-COMPOUNDS TRANSPORTED IN XYLEM OF CASUARINA SP1991In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 42, no 245, p. 1493-1497Article in journal (Refereed)
    Abstract [en]

    Seedlings (180-d-old) of Casuarina cunninghamiana L., C. equisetifolia Miq. and C. glauca Sieber inoculated with each of two different sources of Frankia, were analysed for translocated nitrogenous compounds in xylem sap. Analyses were also made on sap from nodulated and non-nodulated plants of C. glauca grown with or without a range of levels of combined nitrogen. Xylem exudates were collected from stems, roots, and individual nodules of nodulated plants and from stems and roots of non-nodulated plants. While the proportional composition of solutes varied, the same range of amino compounds was found in xylem sap from the three different symbioses. In C. glauca asparagine was the major amino acid in the root sap followed by proline, while in symbiotic C. cunninghamiana arginine accounted for more than 25% of the amino compounds. Citrulline was the major translocated product found in the stem exudate of symbiotic C. equisetifolia. Increasing concentrations of ammonium nitrate in the nutrient solution resulted in increasing levels of free ammonia and glutamine in xylem sap from stems of nodulated and non-nodulated C. glauca, but there was relatively little change in the prominent solutes, e.g. citrulline, proline, and arginine. The composition of nitrogenous solutes in stem or root exudates of C. glauca was similar to that of exudate collected from individual nodules and on this basis it was not possible to distinguish specific products of current N2 fixation in xylem. The main differences in N solute composition between the symbioses were apparently due to host plant effects rather than nodulation or the levels of combined N. Also, the data indicate that the use of the proportion of N in sap as citrulline (or indeed any other orgnaic N solute) could not be used as an index of nitrogen fixation.

  • 30.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    HUSSDANELL, K
    BIOMASS PRODUCTION AND NITROGEN-UTILIZATION BY ALNUS-INCANA WHEN GROWN ON N-2 OR NH4+ MADE AVAILABLE AT THE SAME RATE1986In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 167, no 3, p. 387-394Article in journal (Refereed)
  • 31.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    HUSSDANELL, K
    GROWTH, NITROGEN-FIXATION AND RELATIVE EFFICIENCY OF NITROGENASE IN ALNUS-INCANA GROWN IN DIFFERENT CULTIVATION SYSTEMS1984In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 78, no 1-2, p. 147-158Article in journal (Refereed)
  • 32.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    HUSSDANELL, K
    AHLQVIST, AS
    NITROGEN-FIXATION AND BIOMASS PRODUCTION IN SYMBIOSES BETWEEN ALNUS-INCANA AND FRANKIA STRAINS WITH DIFFERENT HYDROGEN METABOLISM1986In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 66, no 1, p. 99-107Article in journal (Refereed)
  • 33.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    LINDBLAD, P
    ACTIVITIES, OCCURRENCE, AND LOCALIZATION OF HYDROGENASE IN FREE-LIVING AND SYMBIOTIC FRANKIA1990In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 92, no 3, p. 809-815Article in journal (Refereed)
  • 34.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Normand, Philippe
    Dawson, Jeff
    Frankia – the friendly bacteria – infecting actinorhizal plants2007In: Physiologia Plantarum, Vol. 130, p. 315-317Article in journal (Refereed)
  • 35.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    REDDELL, P
    ROSBROOK, P
    THE OCCURRENCE OF HEMOGLOBIN AND HYDROGENASE IN NODULES OF 12 CASUARINA-FRANKIA SYMBIOTIC ASSOCIATIONS1991In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 82, no 3, p. 458-464Article in journal (Refereed)
    Abstract [en]

    Seedlings of Casuarina cunninghamiana Miq., C. equisetifolia L. and C. glauca Sieber growing in N-deficient potting mix were inoculated with Frankia sp. from each of 4 different sources. After ca 4 months, plants were harvested and nodules from the 12 Casuarina-Frankia combinations evaluated for (1) concentrations of haemoglobin (measured as CO-reactive haem) and (2) occurrence of hydrogenase. The aim was to determine if these factors were related to nitrogen accumulation and biomass production. There were marked host-Frankia source interactions with up to 10-fold differences in plant dry weight and 50-fold differences in the efficiency of nitrogen fixation (as estimated by N2 accumulated mg-1 nodule dry weight). Differences in plant growth and nitrogen accumulation were apparently related to nodule specific activity, because the 12 associations had similar nodulation characteristics, e.g. for time for nodulation to occur. The concentration of haemoglobin in Casuarina nodules ranged from 0 to 27 nmol haem (g FW)-1. There was a strong linear correlation between concentrations of haemoglobin and dry weights of the whole plants (r = 0.77, 0.92 and 0.97, P less-than-or-equal-to 0.05) for C. cunninghamiana, C. equisetifolia and C. glauca symbiotic associations, respectively. However, the linear correlation between concentration of haemoglobin and nitrogen content of whole plant was lower (r = 0.60, 0.64 and 0.71, P less-than-or-equal-to 0.05) for the three Casuarina symbioses, respectively, and there was only a poor correlation between haemoglobin concentration in nodules and the rate of nitrogen accumulation on nodule weight basis. This indicates that haemoglobin concentration is not the sole physiological determinant of nitrogen fixation in Casuarina. All the Casuarina-Frankia symbiotic associations studied also showed the presence of a hydrogen uptake enzyme. The activity of the enzyme ranged from 5.1 to 34.1-mu-mol H2 (g FW)-1 h-1, and hydrogen uptake was not correlated with plant dry weight, nitrogen content or the rate of nitrogen fixation. Hydrogen evolution could not be detected in any of the associations.

  • 36.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Richau, Kerstin
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Aspects of nitrogen-fixing Actinobacteria, in particular free-living and symbiotic Frankia2013In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 342, no 2, p. 179-186Article, review/survey (Refereed)
    Abstract [en]

    Studies of nitrogen-fixing properties among the Gram-positive Actinobacteria revealed that some species of Arthrobacter, Agromyces, Corynebacterium, Mycobacterium, Micromonospora, Propionibacteria and Streptomyces have nitrogen-fixing capacity. This is also valid for Frankia that fix nitrogen both in free-living and in symbiotic conditions. Frankia symbiosis results from interaction between the Frankia bacteria and dicotyledonous plants, that is, actinorhiza. These plants, which are important in forestry and agroforestry, form, together with the legumes (Fabales), a single nitrogen-fixing clade. It has been shown that a receptor-like kinase gene, SymRK, is necessary for nodulation in actinorhizal plants as well as in legumes and arbuscular mycorrhizal fungi. Recently, the involvement of isoflavonoids as signal molecules during nodulation of an actinorhizal plant was shown. The genome sizes of three Frankia species, Frankia EANpec, ACN14a and CcI3, are different, revealing a relationship between genome size and geographical distribution. Recent genomic sequencing data of Frankia represent genomes from cluster I to IV, indicating that the genome of DgI is one of the smallest genomes in Frankia. In addition, nonsymbiotic Frankiales such as Acidothermus cellulolyticus, Blastococcus saxoobsidens, Geodermatophilus obscurus and Modestobacter marinus have a variety of genome sizes ranging from 2.4 to 5.57Mb.

  • 37.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    ROSBROOK, PA
    KANG, L
    REDDELL, P
    EFFECT OF CARBON SOURCE ON GROWTH, NITROGENASE AND UPTAKE HYDROGENASE ACTIVITIES OF FRANKIA ISOLATES FROM CASUARINA SP1994In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 158, no 1, p. 63-68Article in journal (Refereed)
    Abstract [en]

    The effect of different carbon sources on the growth of Frankia isolates for Casuarina sp. was studied. In addition, regulation of nitrogenase and uptake hydrogenase activity by carbon sources was investigated. For each of the three isolates, JCT287, KB5 and HFPCcI3, growth was greatest on the carbon sources pyruvate and propionate. In general the carbon sources which gave the greatest growth gave the highest levels of nitrogenase activity, but repressed the activity of uptake hydrogenase. The regulation of growth, uptake hydrogenase activity and nitrogenase activity is discussed.

  • 38.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    WINSHIP, LJ
    ACETYLENE, NOT ETHYLENE, INACTIVATES THE UPTAKE HYDROGENASE OF ACTINORHIZAL NODULES DURING ACETYLENE-REDUCTION ASSAYS1990In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 94, no 1, p. 91-94Article in journal (Refereed)
  • 39.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    WINSHIP, LJ
    HYDROGEN METABOLISM OF CASUARINA ROOT-NODULES - A COMPARISON OF 2 INOCULUM SOURCES1987In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 70, no 2, p. 367-372Article in journal (Refereed)
  • 40.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    WULLINGS, B
    NYSTROM, U
    Gustafsson, Petter
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    IDENTIFICATION OF CASUARINA-FRANKIA STRAINS BY USE OF POLYMERASE CHAIN-REACTION (PCR) WITH ARBITRARY PRIMERS1992In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 93, no 1, p. 1-5Article in journal (Refereed)
    Abstract [en]

    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.

  • 41.
    Sellstedt, Anita
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    WULLINGS, B
    NYSTROM, U
    Gustafsson, Petter
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    IDENTIFICATION OF CASUARINA-FRANKIA STRAINS BY USE OF POLYMERASE CHAIN-REACTION (PCR) WITH ARBITRARY PRIMERS1992In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 93, no 1, p. 1-5Article in journal (Refereed)
    Abstract [en]

    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.

  • 42. Ståhl, Lena
    et al.
    Högberg, Peter
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Buresh, Roland J
    Measuring nitrogen fixation by Sesbania sesban planted fallows using 15N tracer technique in Kenya2005In: Agroforestry Systems, Vol. 65, p. 67-79Article in journal (Refereed)
    Abstract [en]

    A field experiment was performed in eastern Kenya to estimate N2 fixation by Sesbania sesban over an 18-month period using the 15N dilution method. The influence of three reference species, Senna spectabilis, Eucalyptus saligna and Grevillea robusta, on the estimates of N2 fixation was also assessed. Percentage Ndfa (nitrogen derived from the atmosphere) was calculated based on foliar atom excess (FAE), above-ground atom excess (AAE) or whole tree atom excess (WAE) data. The differences in atom% 15N excess values between species and plant parts are presented and discussed. We recommend the use of several reference species for estimating %Ndfa and that the different results obtained should be carefully considered in relation to the issues being addressed. In this study, Senna was the most suitable of the three reference species because its N uptake pattern and phenology were very similar to those of Sesbania. When well established, the amount of N fixed by Sesbania accounts for more than 80% of its total N content, according to FAE-based estimates. We estimated the Ndfa by Sesbania after 18 months to between 500 and 600 kg ha−1 , depending on whether FAE, AAE or WAE data were used and on the choice of reference species. The substantial accumulation of N in planted Sesbania highlighted its potential to increase the sustainability of crop production on N-limited soils. We consider the 15N dilution method to be appropriate for quantifying N2 fixation in improved fallows in studies, similar to this one, of young trees with high N2-fixing ability.

  • 43. Tavares, F
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    A simple, rapid and non-destructive procedure to extract cell wall-associated proteins from Frankia2000In: Journal of Microbiological Methods, ISSN 0167-7012, E-ISSN 1872-8359, Vol. 39, no 2, p. 171-178Article in journal (Refereed)
    Abstract [en]

    A simple cell fractionation procedure was developed to extract cell wall-associated proteins from the nitrogen-fixing actinomycete Frankia. The method was based on washing Frankia mycelia in 62.5 mM Tris-HCl (pH 6.8) buffer supplemented with 0.1% Triton X-100 as solubilizing agent. Cell wall-associated proteins were efficiently extracted in less than 10 min, recovering approximately 94.5+/-7.44 pg protein per extraction procedure from exponentially growing cells, corresponding to 50 ml of culture. The amount of cell lysis occurring during the cell wall extraction was estimated to be 1.50+/-0.51%. Three peptidoglycan hydrolases with apparent molecular masses of 4.7, 12.1, and 17.8 kDa were detected by zymography in the cell wall-associated protein fraction. On the contrary, no cell wall lytic enzyme was detected in the cytoplasmic protein fraction. These results indicate that the present method enables a specific extraction of cell wall-associated proteins. Moreover, fluorescein isothiocyanate (FITC) labelling of the cell surface proteins showed an efficient removal of cell wall-associated proteins. Growth of the treated Frankia cells (i.e. cells from which the cell wall-associated proteins were removed) in semi-solid media suggested that these cells were still viable. This technique is of importance for functionality studies of cell wall-associated proteins, particularly for bacteria where traditional cell fractionation methods are difficult to be applied. (C) 2000 Elsevier Science B.V. All rights reserved.

  • 44. Tavares, F
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    DNase activities of the extracellular, cell wall-associated, and cytoplasmic protein fractions of Frankia strain R431997In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 63, no 11, p. 4597-4599Article in journal (Refereed)
    Abstract [en]

    DNase activities in different protein fractions of Frankia strain R43 were studied. The extracellular and the cell wall-associated fractions revealed the presence of exo- and endonucleolytic enzymes, but none was detected in the cytoplasmic fraction. The strongest DNase hydrolysis was found in the extracellular fraction, in which six DNases were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

  • 45. Tavares, F
    et al.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    DNase-resistant DNA in the extracellular and cell wall-associated fractions of Frankia strains R43 and CcI32001In: Current Microbiology, ISSN 0343-8651, E-ISSN 1432-0991, Vol. 42, no 3, p. 168-172Article in journal (Refereed)
    Abstract [en]

    DNases were shown to be present in the extracellular fraction of Frankia strains R43 and CcI3. In spite of this, DNA was found in both the extracellular and cell wall fractions of these strains, and it was shown that extracellular DNA was resistant to the DNases secreted into the culture medium of both Frankia strains. Furthermore, Southern blot analysis under high stringency conditions revealed the chromosomal origin of the cell wall-adsorbed DNA (CW-DNA). Mobility gel band shift assays suggested that the extracellular DNA and the CW-DNA are engaged in complexes with other molecules, most likely proteins, which are probably responsible for the enzymatic resistance observed against extracellular DNase activities. In addition, it was shown that lysis of a small proportion of the cells in the exponential growth phase may account for the DNA being released into the supernatant and adsorbed to the cell wall.

  • 46.
    Tavares, Fernando
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Department of Botany and Institute for Molecular and Cell Biology, University of Porto, Portugal.
    Bernardo, Lisandro
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Identification and expression studies of a catalase and a bifunctional catalase-peroxidase in Frankia strain R432003In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 254, no 1, p. 75-81Article in journal (Refereed)
    Abstract [en]

    A monofunctional catalase and a bifunctional catalase-peroxidase were revealed by activity staining of non-denaturing PAGE in Frankia strain R43. Both enzymes were shown to be cytoplasmatic, growth regulated and expressed mainly during the stationary growth phase. Nevertheless, low levels of constitutive expression could also be detected during the early stages of growth. Immunoblot analyses using a polyclonal antibody raised against a catalase-peroxidase purified from Streptomyces reticuli showed a band of 83.2 kDa, with the same growth dependent pattern as obtained by the non-denaturing PAGE analyses. Induction studies revealed that both enzymes were strongly induced by raising the intracellular concentration of H2O2 with paraquat, but not with exogenous H2O2. In addition, no acquisition of tolerance to exogenous H2O2 was observed whatever the pretreatment of the inocula, i.e. despite the expression level of both hydroperoxidases.

  • 47. Tavares, Fernando
    et al.
    Santos, Catarina L
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Reactive oxygen species in legume and actinorhizal nitrogen-fixing symbioses: the microsymbiont’s responses to an unfriendly reception2007In: Physiologia Plantarum, Vol. 130, p. 344-356Article in journal (Refereed)
    Abstract [en]

    The plant responses to infection by pathogenic bacteria have been extensively reviewed in recent years, including the spatial and temporal production of reactive oxygen species (ROS). The immediate and localized release of ROS upon infection, known as the oxidative burst, was shown not only to be part of the hypersensitive response but also likely responsible for mediating, directly or via signal transduction pathways, other plant defence strategies. This paradigm inspired studies in nitrogen-fixing root nodule symbioses, and a parallelism is unavoidable. In rhizobia–legume symbioses, histochemical data revealed the presence of ROS in the host infection threads and in the root nodules primordia. On the other hand, in actinorhizal infections, it has been shown that Alnus glutinosa root exudates induce several oxidative stress response-related proteins in compatible Frankia. These data suggest that the nitrogen-fixing microsymbionts must have had to evolve adaptations to overcome and possibly regulate an unfriendly environment. In this review, particular emphasis will be given to the bacteria antioxidant mechanisms at different developmental stages of the nitrogen-fixing root nodule symbioses.

  • 48. WINSHIP, LJ
    et al.
    MARTIN, KJ
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    THE ACETYLENE-REDUCTION ASSAY INACTIVATES ROOT NODULE UPTAKE HYDROGENASE IN SOME ACTINORHIZAL PLANTS1987In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 70, no 2, p. 361-366Article in journal (Refereed)
  • 49.
    Zackrisson, O
    et al.
    Swedish University of Agricultural Sciences Department of Forest Ecology and Management, Umeå, Sweden.
    Deluca, T
    Swedish University of Agricultural Sciences Department of Forest Ecology and Management, Umeå, Sweden.
    Gentili, Francesco
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Jäderlund, A
    Swedish University of Agricultural Sciences Department of Forest Ecology and Management, Umeå, Sweden.
    Nitrogen fixation in mixed Hylocomium splendens moss communities2009In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 160, no 2, p. 309-319Article in journal (Refereed)
    Abstract [en]

    The pleurocarpus feather moss, Hylocomium splendens, is one of two co-dominant moss species in boreal forest ecosystems and one of the most common mosses on earth, yet little is known regarding its capacity to host cyanobacterial associates and thus contribute total ecosystem N. In these studies, we evaluated the N-fixation potential of the H. splendens-cyanobacteria association and contrasted the N-fixation activity with that of the putative N-fixing moss-cyanobacteria association of Pleurozium schreberi. Studies were conducted to: quantify N-fixation in H. splendens and P. schreberi in sites ranging from southern to northern Fennoscandia; assess N and P availability as drivers of N-fixation rates; contrast season-long N-fixation rates for both mosses; and characterize the cyanobacteria that colonize shoots of H. splendens. Nitrogen-fixation rates were generally low at southern latitudes and higher at northern latitudes (64-69 degrees N) potentially related to anthropogenic N deposition across this gradient. Nitrogen fixation in H. splendens appeared to be less sensitive to N deposition than P. schreberi. The season-long assessment of N-fixation rates at a mixed feather moss site in northern Sweden showed that H. splendens fixed a substantial quantity of N, but about 50% less total N compared to the contribution from P. schreberi. In total, both species provided 1.6 kg fixed N ha(-1) year(-1). Interestingly, H. splendens demonstrated somewhat higher N-fixation rates at high fertility sites compared to P. schreberi. Nostoc spp. and Stigonema spp. were the primary cyanobacteria found to colonize H. splendens and P. schreberi. These results suggest that H. splendens with associated Nostoc or Stigonema communities contributes a significant quantity of N to boreal forest ecosystems, but the contribution is subordinate to that of P. schreberi at northern latitudes. Epiphytic cyanobacteria are likely a key factor determining the co-dominant presence of these two feather mosses across the boreal biome.

  • 50. Zackrisson, Olle
    et al.
    DeLuca, Thomas Henry
    Nilsson, Marie-Charlotte
    Sellstedt, Anita
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Berglund, L M
    Nitrogen fixation increases with successional age in boreal forests2004In: Ecology, Vol. 85, p. 3327-3334Article in journal (Refereed)
    Abstract [en]

    There is little understanding of successional dynamics of N fixation in northern boreal forests. Recent evidence suggests that N fixation by cyanobacteria in association with the common feather moss Pleurozium schreberi contributes to a significant proportion of the total N economy. The purpose of the work herein was to determine how time since last fire influences N fixation rates in boreal forests. We evaluated seasonal N fixation rates on a total of 12 natural forest preserves varying in time since last fire (35–355 years). Each site was monitored for N fixation activity using a calibrated acetylene reduction assay. Nitrogen fixation rates were found to increase linearly with time since fire. This increase in N fixation with succession is likely a function of degree of colonization by cyanobacteria and site factors such as presence of available N. Surface applications of 4.5 kg N·ha−1·yr−1 as NH4NO3 were found to eliminate N fixation while applications of P resulted in only a slight and temporary increase of N fixation rates. In contrast to common observation our findings suggest that N fixation in boreal forests becomes more important in late succession. Limited N availability in late succession is clearly one of the primary drivers of N fixation rates in boreal forest ecosystems. These findings may help to explain the origin of high rates of net N accumulation in soil unaccounted for at northern boreal sites.

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