| 1. |
- DeLuca, T H, et al.
(author)
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Quantifying nitrogen-fixation in feather moss carpets of boreal forests
- 2002
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 419:6910, s. 917-920
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Journal article (peer-reviewed)abstract
- 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.
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| 2. |
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| 3. |
- Leitz, G, et al.
(author)
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Laser-based micromanipulation for separation and identification of individual Frankia vesicles
- 2003
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In: FEMS Microbiology Letters. - 0378-1097 .- 1574-6968. ; 224:1, s. 97-100
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Journal article (peer-reviewed)abstract
- 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.
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| 4. |
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| 5. |
- LINDBLAD, P, et al.
(author)
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OCCURRENCE AND LOCALIZATION OF AN UPTAKE HYDROGENASE IN THE FILAMENTOUS HETEROCYSTOUS CYANOBACTERIUM NOSTOC PCC-73102
- 1990
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In: Protoplasma. - 0033-183X .- 1615-6102. ; 159:1, s. 9-15
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Journal article (peer-reviewed)abstract
- 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.
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| 6. |
- Mattsson, U, et al.
(author)
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Frankia KB5 possesses a hydrogenase immunologically related to membrane-bound [NiFe]-hydrogenases
- 2001
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In: Current Microbiology. - 0343-8651 .- 1432-0991. ; 42:6, s. 438-441
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Journal article (peer-reviewed)abstract
- 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.
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| 7. |
- Mattsson, U, et al.
(author)
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Hydrogenase in Frankia KB5 : Expression of and relation to nitrogenase
- 2000
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In: Canadian journal of microbiology (Print). - 0008-4166 .- 1480-3275. ; 46:12, s. 1091-1095
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Journal article (peer-reviewed)abstract
- 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.
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| 8. |
- Mattsson, U, et al.
(author)
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Nickel affects activity more than expression of hydrogenase protein in Frankia
- 2002
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In: Current Microbiology. - 0343-8651 .- 1432-0991. ; 44:2, s. 88-93
-
Journal article (peer-reviewed)abstract
- 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.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Sellstedt, Anita, 1955-, et al.
(author)
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COMPOSITION OF AMINO-COMPOUNDS TRANSPORTED IN XYLEM OF CASUARINA SP
- 1991
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In: Journal of Experimental Botany. - : Oxford University Press (OUP). - 0022-0957 .- 1460-2431. ; 42:245, s. 1493-1497
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Journal article (peer-reviewed)abstract
- 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.
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| 14. |
- Sellstedt, Anita, 1955-, et al.
(author)
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EFFECT OF CARBON SOURCE ON GROWTH, NITROGENASE AND UPTAKE HYDROGENASE ACTIVITIES OF FRANKIA ISOLATES FROM CASUARINA SP
- 1994
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In: Plant and Soil. - 0032-079X .- 1573-5036. ; 158:1, s. 63-68
-
Journal article (peer-reviewed)abstract
- 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.
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| 15. |
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| 16. |
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| 17. |
- Sellstedt, Anita, 1955-, et al.
(author)
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IDENTIFICATION OF CASUARINA-FRANKIA STRAINS BY USE OF POLYMERASE CHAIN-REACTION (PCR) WITH ARBITRARY PRIMERS
- 1992
-
In: FEMS Microbiology Letters. - 0378-1097 .- 1574-6968. ; 93:1, s. 1-5
-
Journal article (peer-reviewed)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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| 18. |
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Sellstedt, Anita, 1955-
(author)
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SPECIFICITY AND EFFECTIVITY IN NODULATION BY FRANKIA ON SOUTHERN-HEMISPHERE ACTINORHIZA
- 1995
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In: FEMS Microbiology Letters. - 0378-1097 .- 1574-6968. ; 125:2-3, s. 231-236
-
Journal article (peer-reviewed)abstract
- 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.
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| 23. |
- Sellstedt, Anita, 1955-, et al.
(author)
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THE OCCURRENCE OF HEMOGLOBIN AND HYDROGENASE IN NODULES OF 12 CASUARINA-FRANKIA SYMBIOTIC ASSOCIATIONS
- 1991
-
In: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 82:3, s. 458-464
-
Journal article (peer-reviewed)abstract
- 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.
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| 24. |
- Tavares, F, et al.
(author)
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A simple, rapid and non-destructive procedure to extract cell wall-associated proteins from Frankia
- 2000
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In: Journal of Microbiological Methods. - 0167-7012 .- 1872-8359. ; 39:2, s. 171-178
-
Journal article (peer-reviewed)abstract
- 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.
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| 25. |
- Tavares, F, et al.
(author)
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DNase activities of the extracellular, cell wall-associated, and cytoplasmic protein fractions of Frankia strain R43
- 1997
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In: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 63:11, s. 4597-4599
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Journal article (peer-reviewed)abstract
- 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.
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