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  • taxonomy  (123)
  • Nitrogen fixation  (122)
  • Springer  (245)
  • American Chemical Society (ACS)
  • American Meteorological Society
  • 2015-2019
  • 2000-2004  (73)
  • 1980-1984  (172)
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  • 1
    Electronic Resource
    Electronic Resource
    Biogeography, geographic variation and habitat preference in the Amazilia Hummingbird,Amazilia amazilia Lesson (Aves: Trochilidae), with notes on the status ofAmazilia alticola Gould (2000)
    Springer
    Journal of ornithology 141 (2000), S. 93-101 
    Details
    ISSN: 1439-0361
    Keywords: Biogeography ; geographic variation ; taxonomy ; Amazilia ; Trochilidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die vorliegende Studie stellt die Ergebnisse von Untersuchungen zur Biogeographie, geographischen Variation, Habitatwahl und Taxonomie der Lesson-Amazilie (Amazilia amazilia) vor. Das Taxon umfaßt gegenwärtig fünf Unterarten, die von W-Ecuador bis SW-Peru verbreitet sind und überwiegend submontane Lebensräume besiedeln. Die Ventralfärbung unterliegt klinaler Variation; weiße Gefiederanteile nehmen von nördlichen zu südlichen Populationen ab, rotbraune Partien dagegen zu. Eigenständige morphologisch-morphometrische Kennzeichen sowie Unterschiede in den Habitatpräferenzen und in der Gesangsstruktur rechtfertigen es, die bisherige UnterartA. a. alticola als Paraspezies (A. alticola, Loja-Amazilie) anzuerkennen. Der Vulgärname weist auf den rezenten Verbreitungsschwerpunkt in den südecuadorianischen Anden hin. Aufgrund der engen Verwandtschaft bildenA. amazilia undA. alticola sowie die in Kolumbien endemische ArtA. castaneiventris eine Superspezies.
    Notes: Summary This paper reviews the biogeography, geographic variation, and habitat characteristics of the Amazilia Hummingbird (Amazilia amazilia). Based on morphological features, habitat preferences, and bioacoustics, I propose that the currently recognized subspeciesA. a. alticola should be regarded as a species distinct fromA. amazilia. Synapomorphic characters found in both taxa indicate membership of the same superspecies, together with the Colombian speciesA. castaneiventris. Considering the distributional focus ofA. alticola in the Andes of southern Ecuador, the English species name Loja Hummingbird is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01651776
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  • 2
    Electronic Resource
    Electronic Resource
    Calls of the Jungle Crow (Corvus macrorhynchos s.l.) as a taxonomic character (2000)
    Springer
    Journal of ornithology 141 (2000), S. 275-284 
    Details
    ISSN: 1439-0361
    Keywords: East Asia ; taxonomy ; species delimitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Über die Gliederung der ostasiatischen Dickschnabelkrähen (Corvus macrorhynchos s.l.) in Biospezies besteht bisher keine einhellige Meinung. In dem großen Verbreitungsgebiet zwischen Indien, Japan und Timor werden gegenwärtig eine, zwei oder drei Arten anerkannt. Hier versuchen wir, in akustischen Merkmalen artanzeigende Merkmale zu finden. Eine Diskriminanzanalyse der Rufstruktur (76 Parameter) trennt dreiCorvus-Taxa (levaillantii undjaponensis aus der ‘macrorhynchos-Gruppe’,splendens) von der Südabdachung des Himalaya (Nepal, Kashmir) vollständig voneinander. BeiC. japonensis bleiben die trennenden Merkmale über große geographische Gebiete konstant. Die akustischen Unterschiede werden als taxonomisch relevant angesehen; sie zeigen Artgrenzen an. Folglich werden die Dickschnabelkrähen aus den Tief- und Hochlagen Nepals (Kontaktzone um 2 000 m) zwei Biospezies zugeordnet (C. japonensis undC. levaillantii), in Übereinstimmung mit morphologischen, ökologischen und parasitologischen Daten. Taxonomische Extrapolation der Befunde auf die Systematik anderer ‘macrorhynchos’-Populationen erscheint über die Rufstruktur (bis zum Fernen Osten Rußlands) und über Federling-Parasiten (Mallophaga) auf große Teile SO-Asiens möglich, bedarf aber für die stimmlichen Merkmale noch weiterer Klärung. Wahrscheinlich müssen immacrorhynchos-Komplex mindestens drei biologische Arten anerkannt werden (C. japonensis, C. levaillantii, C. macrorhynchos s. str.).
    Notes: Summary A discriminant analysis of the call structure completely separates threeCorvus taxa (levaillantii andjaponensis of the ‘macrorhynchos group’,splendens) inhabiting the southern slopes of the Himalayas (Nepal, Kashmir). The acoustic differences are considered taxonomically relevant, indicating species boundaries. Therefore the Jungle Crows of lower and upper Nepal (contact zone at around 2,000 m) are assigned to two biospecies (C. japonensis andC. levaillantii), as is consistent with morphological, ecological and parasitological data. It appears possible to extrapolate the findings regarding call structure to the systematics of other ‘macrorhynchos’ populations as distant as the Russian Far East, and those regarding mallophagan parasites to large areas of SE Asia; regarding the vocal characteristics, however, further clarification is needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02462237
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  • 3
    Electronic Resource
    Electronic Resource
    The "oxygen paradox" of dinitrogen-fixing bacteria (2000)
    Springer
    Biology and fertility of soils 30 (2000), S. 363-373 
    Details
    ISSN: 1432-0789
    Keywords: Key words Azospirillum species ; Oxygen paradox ; Nitrogen fixation ; Rhizosphere ; Nitrogenase complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  N2 fixation by aerobic bacteria is a very energy demanding process, requiring efficient oxidative phosphorylation, while O2 is toxic for the nitrogenase complex. N2-fixing bacteria have evolved a variety of strategies to cope with this apparent "O2 paradox". This review compares strategies that azospirilla and other well-known N2-fixing soil bacteria use to overcome this O2 paradox. Attention will be given to the relationships between the natural habitat of these soil bacteria and their prevailing adaptations. In view of this knowledge the following questions will be addressed: are the specific adaptations observed in azospirilla sufficient to allow optimal proliferation and N2 fixation in their natural habitat? Could improving the O2 tolerance of the N2-fixing process contribute to the development of more efficient strains for the inoculation of plants?
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050017
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  • 4
    Electronic Resource
    Electronic Resource
    Genetic variability in dinitrogen fixation between cowpea [Vigna unguiculata (L.) Walp] cultivars determined using the nitrogen-15 isotope dilution technique (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 318-320 
    Details
    ISSN: 1432-0789
    Keywords: Key words Genetic variability ; Vigna unguiculata ; Nitrogen-15 method ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  N fixed in 16 cultivars of cowpea [Vigna unguiculata (L.) Walp] inoculated with effective Bradyrhizobium strains collected from the West African MIRCEN culture collection was measured by 15N isotope dilution technique. In all plant parts, significant differences in the percentage of N derived from the atmosphere (%Ndfa) and the amount of Ndfa occurred between the cultivars. Ndoute variety exhibited the highest %Ndfa (74.33% in shoots; 60.90% in roots) and accumulated more fixed N (960 mg N plant–1 and 38 mg N plant–1 in shoots and roots, respectively). Therefore this cultivar should be selected as the highest N-fixing cowpea cultivar. It also should be used in a breeding programme to contribute to the development of cultivars that could stimulate an intensive use of cowpea in many different cropping systems in Africa with a view to maintaining soil fertility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000254
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  • 5
    Electronic Resource
    Electronic Resource
    Field evaluation of lentil cultivars inoculated with Rhizobium leguminosarum bv. viciae strains for nitrogen fixation using nitrogen-15 isotope dilution (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 65-69 
    Details
    ISSN: 1432-0789
    Keywords: Key words Nitrogen-15 isotope dilution ; Legumes ; Lens culinaris ; Rhizobium ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  A 15N isotope dilution technique was applied to quantify the extent of N2 fixation in lentil (Lens culinaris Medik.) cultivars as influenced by Rhizobium leguminosarum bv. viciae strains in a field experiment in Pakistan. The experiment was conducted on a soil with a very small indigenous rhizobial population and where N was a limiting factor for crop production. Significant variations in number of nodules, dry weight of nodules, biomass yield, grain yield, total N yield, proportion of plant N derived from N2 fixation (Pfix) and amount of N derived from the atmosphere (Ndfa) were observed among combined treatments of four rhizobial strains and six lentil varieties. In a field previously labelled with 15N, to which a basal dose of 75 kg P2O5 ha–1 was applied as single super phosphate, Ndfa ranged from 15 to 24 kg N ha–1 when calculated according to rhizobial strain and from 4 to 38 kg N ha–1 when calculated according to lentil variety. Lc 26 was the most effective strain and fixed 243% more N than the indigenous population in the uninoculated control. In treatments with the lentil variety PL-406, Ndfa was 38 kg N ha–1, which was 850% higher than with the lentil variety Precoz/F6-20-1×M-85. Generally, the varieties with greater Pfix produced a higher dry matter yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050625
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  • 6
    Electronic Resource
    Electronic Resource
    Inoculation of rice plants with the endophytic diazotrophs Herbaspirillum seropedicae and Burkholderia spp. (2000)
    Springer
    Biology and fertility of soils 30 (2000), S. 485-491 
    Details
    ISSN: 1432-0789
    Keywords: Key words Herbaspirillum seropedicae ; Burkholderia spp. ; Nitrogen fixation ; Rice ; Gnotobiotic conditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Four experiments were performed under gnotobiotic conditions to select strains of the endophytic diazotrophs Herbaspirillum seropedicae and Burkholderia spp. as inocula of rice plants. Eighty strains of H. seropedicae originally isolated from rice, sorghum and maize plants, were tested in test tube cultures with N-free agar as the substrate. Rice plants showed medium and high increases in their fresh weight in response to inoculation with nineteen strains. These strains were tested again, and six strains were then selected to evaluate their contribution to the N of the plant via biological N2 fixation (BNF) using an agar growth medium containing 5 mg N l–1of 15N-labelled (NH4)2SO4. The contribution of the strains to plant N via BNF varied from 54% when rice plants were inoculated with strain ZAE94, to 31% when strain ZAE67 was used. These results were confirmed in the fourth gnotobiotic experiment, which also included strains of the new N-fixing bacteria belonging to the genus Burkholderia, isolated from rice, as well as a strain of Burkholderia vietnamiensis, isolated from rice rhizosphere. Burkholderia spp. strains showed similar effects to those observed for H. seropedicae strains, while B. vietnamiensis fixed only 19% of plant total N. The best four strains were tested in a pot experiment where pre-germinated, inoculated rice seedlings were grown in soil labelled with 15N. The results confirmed the gnotobiotic experiments, although the levels of N in the rice plants derived from BNF of the selected H. seropedicae and Burkholderia spp. strains were lower. Nevertheless, there was an increase in N content in grains of inoculated plants, and the results showed that the method used for strain selection is very useful and can be applied to other strains of N2-fixing bacteria and plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050027
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  • 7
    Electronic Resource
    Electronic Resource
    Fallow residue management effects on upland rice in three agroecological zones of West Africa (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 501-507 
    Details
    ISSN: 1432-0789
    Keywords: Key words Fallow ; Legumes ; Nitrogen fixation ; Oryza sativa ; Côte d'Ivoire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Improving fallow quality in upland rice-fallow rotations in West Africa through the site-specific use of leguminous cover crops has been shown to sustain the productivity of such systems. We studied the effects of a range of residue management practices (removal, burning, mulching and incorporation) on fallow biomass and N accumulation, on weed biomass and yield response of upland rice and on changes in soil physical and chemical characteristics in 2-year field trials conducted in three agroecological zones of Côte d'Ivoire. Across fallow management treatments and agroecological zones, rice yields were on average 20–30% higher in legume than in natural fallow plots. Weed biomass was highest in the savanna zone and lowest in the bimodal forest and tended to be less following a legume fallow. Regardless of the type of fallow vegetation and agroecological zone, biomass removal resulted in the lowest rice yields that varied from 0.5 t ha–1 in the derived savanna zone to 1.5 t ha–1 in the Guinea savanna zone. Burning of the fallow vegetation significantly increased yield over residue removal in the derived savanna (0.27 t ha–1, P〈0.05) and bimodal forest zones (0.27 t ha–1, P〈0.01), but not in the Guinea savanna. In both savanna environments, residue incorporation was superior to the farmers' practice of residue removal and rice yield increases were related to amounts of fallow N returned to the soil (r 2=0.803, P〈0.01). In the forest zone, the farmers' practice of residue burning produced the highest yield (1.43 t ha-1 in the case of legumes) and resulted in the lowest weed biomass (0.02 t ha–1). Regardless of the site, improving the quality of the fallow or of its management had no significant effects on either soil physical or soil chemical characteristics after two fallow cycles. We conclude that incorporation of legume residues is a desirable practice for rice-based fallow rotation systems in savanna environments. No promising residue management alternatives to slash-and-burn were apparent for the forest zone. Determining the possible effects on soil productivity will require longer-term experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000199
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  • 8
    Electronic Resource
    Electronic Resource
    The evolution of a plant globin gene family (1984)
    Springer
    Journal of molecular evolution 21 (1984), S. 19-32 
    Details
    ISSN: 1432-1432
    Keywords: Leghemoglobin ; Gene duplication ; Gene linkage ; Concerted evolution ; Nitrogen fixation ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed the sequences of soybean leghemoglobin genes as an initial step toward understanding their mode of evolution. Alignment of the sequences of plant globin genes with those of animals reveals that (i) based on the proportion of nucleotide substitutions that have occurred at the first, second, and third codon positions, the time of divergence of plant and animal globin gene families appears to be extremely remote (between 900 million and 1.4 billion years ago, if one assumes constancy of evolutionary rate in both the plant and animal lineages) and (ii) in addition to the normal regulatory sequences on the 5′ end, an approximately 30-base-pair sequence, specific to globin genes, that surrounds the cap site is conserved between the plant and animal globin genes. Comparison of the leghemoglobin sequences with one another shows that (i) the relative amount of sequence divergence in various coding and noncoding regions is roughly similar to that found for animal globin genes and (ii) as in animal globin genes, the positions of insertions and deletions in the intervening sequences often coincide with the locations of direct repeats. Thus, the mode of evolution of the plant globin genes appears to resemble, in many ways, that of their animal counterparts. We contrast the overall intergenic organization of the plant globin genes with that of animal genes, and discuss the possibility of the concerted evolution of the leghemoglobin genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02100624
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  • 9
    Electronic Resource
    Electronic Resource
    Questioning species realities (2000)
    Springer
    Conservation genetics 1 (2000), S. 67-76 
    Details
    ISSN: 1572-9737
    Keywords: mitochondrial DNA ; phylogeny ; phylogeography ; speciation ; species concepts ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010133721121
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  • 10
    Electronic Resource
    Electronic Resource
    Building on Bedrock: William Steel Creighton and the Reformation of Ant Systematics, 1925–1970 (2000)
    Springer
    Journal of the history of biology 33 (2000), S. 27-70 
    Details
    ISSN: 1573-0387
    Keywords: ants ; E. O. Wilson ; Ernst Mayr ; systematics ; Systematics and the Origin of Species ; taxonomy ; William L. Brown ; William Morton Wheeler ; William Steel Creighton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract Ideas about the natural world are intertwined with the personalities, practices, and the workplaces of scientists. The relationships between these categories are explored in the life of the taxonomist William Steel Creighton. Creighton studied taxonomy under William Morton Wheeler at Harvard University. He took the rules he learned from Wheeler out of the museum and into the field. In testing the rules against a new situation, Creighton found them wanting. He sought a new set of taxonomic principles, one he eventually found in Ernst Mayr's Systematics and the Origin of Species. Mayr's ideas tied together a number of themes running through Creighton's life: the need for a revised taxonomy, the emphasis on fieldwork, and the search for a new power center for ant taxonomy after Wheeler died. Creighton's adoption of Mayr's ideas as part of his professional identity also had very real implications for his career path: field studies required long and intensive studies, and Creighton would always be a slow worker. His method of taxonomy contrasted sharply not only with Wheeler's but also with two of his younger colleagues, William L. Brown and E. O. Wilson, who took over Wheeler's spot at Harvard in 1950. The disputes between these men over ant taxonomy involved, in addition to questions of technical interest, questions about where and how best to do taxonomy and who could speak withthe most authority. Creighton's story reveals how these questions are interrelated. The story also reveals the importance of Mayr's book for changes occurring in taxonomy in the middle of the twentieth century.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004712911037
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  • 11
    Electronic Resource
    Electronic Resource
    Ammonium effects on function and structure of nitrogen-fixing root nodules of Alnus incana (L.) Moench (1982)
    Springer
    Planta 156 (1982), S. 332-340 
    Details
    ISSN: 1432-2048
    Keywords: Alnus ; Ammonium ; Carbon translocation ; Endophyte damage ; Nitrogen fixation ; Root nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cloned plants of Alnus incana (L.) Moench were inoculated and grown without combined nitrogen for seven weeks. The effects of ammonium on the function and structure of the root nodules were studied by adding 20 mM NH4Cl (20 mM KCl=control) for four days. Nitrogenase activity decreased to ca. 50% after one day and to less than 10% after two days in ammonium treated plants, but was unaffected in control plants. The results were similar at photon flux densities of 200 and 50 μmol m-2 s-1. At the higher light level the effect was concentration dependent between 2 and 20 mM NH4Cl. The recovery was slow, and more than 11 d were needed for plants treated with 20 mM ammonium to reach initial activity. The distribution of 14C to the root nodules after assimilation of 14CO2 by the plants was not changed by the ammonium treatment. Microscopical studies of root nodules showed high frequencies of endophyte vesicles being visually damaged in nodules from ammonium-treated plants, but not in nodules from control plants. When nitrogenase activity was restored, visually damaged vesicles were again few, whereas young developing vesicles were numerous. The slow recovery, the 14C-translocation pattern, and the structural changes of the endophyte indicate a more complex mechanism of ammonium influence than simply a short-term reduction in supply of carbon compounds to the nodules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397471
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  • 12
    Electronic Resource
    Electronic Resource
    Nitrogen nutrition and the development of biochemical functions associated with nitrogen fixation and ammonia assimilation of nodules on cowpea seedlings (1984)
    Springer
    Planta 162 (1984), S. 327-333 
    Details
    ISSN: 1432-2048
    Keywords: Ammonia ; Nitrogen fixation ; Nodule ; Senescence (root nodules) ; Ureide ; Vigna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During early development (up to 18 d after sowing) of nodules of an “effective” cowpea symbiosis (Vigna unguiculata (L.) Walp cv. Vita 3: Rhizobium strain CB756), rapidly increasing nitrogenase (EC 1.7.99.2) activity and leghaemoglobin content were accompanied by rapid increases in activities of glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 2.6.1.53), enzymes of denovo purine synthesis (forming inosine monophosphate) xanthine oxidoreductase (EC 1.2.3.2), urate oxidase (EC 1.7.3.3), phosphoenolpyruvate carboxylase (EC 4.1.1.31) and led to increased export of ureides (allantoin and allantoic acid) to the shoot of the host plant in the xylem. Culturing plants with the nodulated root systems maintained in the absence of N2 (in 80 Ar: 20 O2, v/v) had little effect on the rates of induction and increase in nitrogenase activity and leghaemoglobin content but, in the absence of N2 fixation and consequent ammonia production by bacteroids, there was no stimulation of activity of enzymes of ammonia assimilation or of the synthesis of purines or ureides. Addition of NO 3 - (0.1–0.2 mM) relieved host-plant nitrogen deficiency caused by the Ar: O2 treatment but failed to increase levels of enzymes of N metabolism in either the bacteroid or the plant-cell fractions of the nodule. Premature senescence in Ar: O2-grown nodules occurred at 18–20 d after sowing, and resulted in reduced levels of nitrogenase activity and leghaemoglobin but increased the activity of hydroxybutyrate oxidoreductase (EC 1.1.1.30).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396744
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  • 13
    Electronic Resource
    Electronic Resource
    Subcellular organization of ureide biogenesis from glycolytic intermediates and ammonium in nitrogen-fixing soybean nodules (1982)
    Springer
    Planta 155 (1982), S. 45-51 
    Details
    ISSN: 1432-2048
    Keywords: Ammonium assimilation ; Glycine ; Nitrogen fixation ; Proplastid ; Purine synthesis ; Root nodule ; Ureide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Subcellular organelle fractionation of nitrogen-fixing nodules of soybean (Glycine max (L.) Merr.) indicates that a number of enzymes involved in the assimilation of ammonia into amino acids and purines are located in the proplastids. These include asparagine synthetase (EC 6.3.1.1), phosphoribosyl amidotransferase (EC 2.4.2.14), phosphoglycerate dehydrogenase (EC 1.1.1.95), serine hydroxymethylase (EC 2.1.2.1), and methylene-tetrahydrofolate dehydrogenase (EC 1.5.1.5). Of the two isoenzymes of asparate aminotransferase (EC 2.6.1.1) in the nodule, only one was located in the proplastid fraction. Both glutamate synthase (EC 1.4.1.14) and triosephosphate isomerase (EC 5.3.1.1) were associated at least in part with the proplastids. Glutamine synthetase (EC 6.3.1.2) and xanthine dehydrogenase (EC 1.2.1.37) were found in significant quantities only in the soluble fraction. Phosphoribosylpyrophosphate synthetase (EC 2.7.6.1) was found mostly in the soluble fraction, although small amounts of it were detected in other organelle fractions. These results together with recent organelle fractionation and electron microscopic studies form the basis for a model of the subcellular distribution of ammonium assimilation, amide synthesis and uredie biogenesis in the nodule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402930
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  • 14
    Electronic Resource
    Electronic Resource
    Effects of combined nitrogen on anapleurotic carbon assimilation and bleeding sap composition in Phaseolus vulgaris L. (1980)
    Springer
    Planta 148 (1980), S. 338-345 
    Details
    ISSN: 1432-2048
    Keywords: Allantoin ; Amino acids ; Bleeding sap ; Nitrogen fixation ; Phaseolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dwarf french beans, Phaseolus vulgaris L., were grown with or without inoculation with rhizobia (strain 3644), and with or without a combined nitrogen source (nitrate or ammonium ions). The distribution of radioactivity into products of dark 14CO2 assimilation was studied in roots or nodules from these plants. A detailed study was also made of the distribution and rates of excretion of nitrogen in xylem bleeding sap in 28 day old plants grown on the various sources of nitrogen. Whereas detached nodules accumulated radioactive glycine, serine and glutamate when incubated with 14CO2, bleeding sap from plants root fed 14CO2 contained low levels of radioactivity in these compounds but higher levels in allantoin. Chemical analysis showed allantoin to be the major compound transported in the xylem of nodulated plants, whether or not they were fed on combined nitrogen. In contrast uninoculated plants accumulated mainly amino acids in the bleeding sap, the amount and chemical composition of which depended on the combined nitrogen source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388121
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  • 15
    Electronic Resource
    Electronic Resource
    Effect of chemical inhibitors of photorespiration on nitrogenase activity in nodulated alfalfa plants (1980)
    Springer
    Planta 150 (1980), S. 299-302 
    Details
    ISSN: 1432-2048
    Keywords: Glyoxylate ; Isonicotinic acid hydracide ; Medicago ; Nitrogen fixation ; Photorespiration ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogen fixation (measured as acetylene reduction) by whole nodulated alfalfa plants was stimulated when the plants were treated with isonicotinic acid hydracide (INH) and glyoxylate, both inhibitors of the glycolate pathway of carbohydrate metabolism, at concentrations of 300 and 100 mM, respectively. Reducing energetic loses caused by photorespiration results in an increase in the symbiotic nitrogen fixation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384659
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  • 16
    Electronic Resource
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    15N2 Incorporation and metabolism in the lichen Peltigera aphthosa Willd (1981)
    Springer
    Planta 152 (1981), S. 544-552 
    Details
    ISSN: 1432-2048
    Keywords: Ammonium assimilation ; Lichens ; Nitrogen fixation ; Peltigera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Nostoc in the cephalodia of the lichen Peltigera aphthosa Willd. fixed 15N2 and the bulk of the nitrogen fixed was continuously transferred from it to its eukaryotic partners (a fungus and a green alga, Coccomyxa sp.). Kinetic studies carried out over the first 30 min, after exposure of isolated cephalodia to 15N2, showed that highest initial 15N2-labelling was into NH 4 + . After 12 min little further increase in the NH 4 + label occurred while that in the amide group of glutamine and in glutamate continued to increase. The 15N-labelling of the amino group of glutamine and of aspartate increased more slowly, followed by an increase in the labelling of alanine. When total incorporation of 15N-label was calculated, the overall pattern was found to be rather similar except that, throughout the experiment, the total 15N incorporated into glutamate was about six times greater than that into the amide group of glutamine. Pulse chase experiments, in which 14N2 was added to cephalodia previously exposed to 15N2, showed that the NH 4 + pool rapidly became depleted of 15N-label, followed by decreases in the labelling of glutamate, the amide group of glutamine and aspartate. The 15N-labelling of alanine, however, continued to increase for a period. When isolated cephalodia were treated with L-methionine-SR-sulphoximine, an inhibitor of glutamine synthetase (EC 6.3.1.2), and azaserine, an inhibitor of glutamate synthase (EC 2.6.1.53), there was no detectable labelling in glutamine although the 15N-labelling of glutamate increased unimpaired. On treating the cephalodia with amino-oxyacetate, an inhibitor of aminotransferase activity, the alanine pool decreased. Evidence was obtained that glutamine synthetase and glutamate synthase were located in the Nostoc, and that glutamate dehydrogenase (EC 1.4.1.4) and various amino-transferases were located in the cephalodial fungus. Possible implications of these findings are discussed.
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    Agricultural nitrogen model: A tool for regional environmental management (1983)
    Springer
    Environmental management 7 (1983), S. 177-187 
    Details
    ISSN: 1432-1009
    Keywords: Nitrogen ; Model ; Agriculture ; Mass balance ; Ground-water ; Denitrification ; Immobilization ; Dry deposition ; Nitrogen fixation ; Nitrate ; Florida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A detailed nitrogen budget was devised for agricultural activities in the Florida peninsula, based on routine data published by state agricultural agencies. The model demonstrates that important unmonitored fluxes of nitrogen can often be calculated by mass balance on individual model compartments, and that the reasonability of poorly quantified fluxes can be assessed. The results of such models can be very useful in designing and assessing the results of field experiments and in prioritizing environmental monitoring programs.
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    Relative levels of guanosine 5′-diphosphate 3′-diphosphate (ppGpp) in some N2 fixing bacteria during derepression and repression of nitrogenase (1981)
    Springer
    Archives of microbiology 128 (1981), S. 341-342 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Regulation ; Guanosine 5′-diphosphate 3′-diphosphate (ppGpp)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Addition of ammonium to N2 fixing cultures of Azotobacter vinelandii, Klebsiella pneumoniae and Clostridium pasteurianum rapidly reduced the intracellular levels of guanosine 5′-diphosphate 3′-diphosphate (ppGpp) by 70–90%. This change might reflect a regulatory role of ppGpp in nitrogen metabolism.
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    Hydrogen uptake deficient mutants of Rhodopseudomonas capsulata (1983)
    Springer
    Archives of microbiology 136 (1983), S. 20-25 
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    ISSN: 1432-072X
    Keywords: Hydrogen production ; Nitrogen fixation ; Hydrogen recycling ; Hydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutants of Rhodopseudomonas capsulata lacking uptake hydrogenase activity have been isolated among those unable to grow photoautotrophically. Studies with these mutants showed increases in nitrogenase mediated H2 production from all substrates tested. In addition, photosynthetic synthetic growth on N2 with malate as carbon source was not affeced by the block in H2 uptake even under low light. Under these growth conditions hydrogen was observed to accumulate in mutant but not in wild-type cultures. This finding suggested that H2 was evolved by nitrogenase during N2 fixation by this photosynthetic bacterium and was efficiently recycled in the wild type.
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  • 20
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    Effect of oxygen concentration on dark nitrogen fixation and respiration in cyanobacteria (1983)
    Springer
    Archives of microbiology 135 (1983), S. 287-292 
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    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Respiration ; Nitrogen fixation ; Heterocysts ; K m for O2 ; Anabaena variabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous measurements of acetylene reduction by Anabaena variabilis and the concentration of dissolved oxygen in the suspension were made using a specially designed vessel which allowed measurements under steady-state conditions. The rate of acetylene reduction in the dark increased with increasing oxygen concentrations until a maximum value was reached at 300 μM O2 (corresponding to 30% O2 in the gas phase at 35°C). This presumably results from a requirement for energy provided by respiration. Measurements of the dependence of respiration rate on dissolved oxygen concentration were made under comparable conditions using an open system to allow conditions close to steady-state to be obtained. The respiration rate of diazotrophically grown Anabaena variabilis had a dependence on oxygen concentration corresponding to the sum of two activities. These had K m values of 1.0 μM and 69 μM and values of V max of similar magnitude. Only the high affinity activity was observed in nitrate-grown cyanobacteria lacking heterocysts, and this presumably represent activity in the vegetative cells. The oxygen concentration dependence of the low affinity activity resembled that for the stimulation of acetylene reduction. We interpret this as the result of oxygen uptake by the heterocysts. The results are consistent with the idea that in intact filaments of cyanobacteria O2 enters heterocysts much more slowly than it enters the vegetative cells.
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  • 21
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    The relationship between the state of adenylylation of glutamine synthetase I and the export of ammonium in free-living, N2-fixing Rhizobium (1984)
    Springer
    Archives of microbiology 138 (1984), S. 26-30 
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    ISSN: 1432-072X
    Keywords: Ammonium export ; Ammonium assimilation ; Glutamine synthetase ; Nitrogen fixation ; Rhizobium sp. 32H1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between ammonium assimilation and ammonium export has been studied in free-living, N2-fixing Rhizobium sp. 32H1. After 55 to 67 h of microaerobic growth under a gas phase of 0.2% O2 – 1.0% CO2 – 98.8% Ar high levels of nitrogenase were observed concomitant with a slightly adenylylated glutamine synthetase (GSI) and some glutamine synthetase (GSII) activity. However, after growth of 89 h, or longer, GSI became adenylylated and the level of GSII had decreased. When the gas phase was shifted to 0.2% O2 – 1.0% CO2 – 98.8% N2, a lag was observed before ammonium export could be detected in the 55 to 67 h cultures. No lag in ammonium export was observed in the cultures previously grown for 89 h. The onset of ammonium export in the 55 to 67 h cultures was found to correlate with the adenylylation state of GSI. There appeared to be no correlation between the level of GSII and the export of ammonium. Neither an increase in the adenylylation level of GSI nor ammonium export was observed when the 55 to 67 h cultures were maintained under the Ar gas mixture.
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    The occurrence of coryneform bacteria in the leaf cavity of Azolla (1980)
    Springer
    Archives of microbiology 127 (1980), S. 163-165 
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    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Arthrobacter ; Corynebacterium ; Anabaena azollae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Coryneform bacteria were found associated with the nitrogen fixing blue-green alga, Anabaena azollae in the leaf cavity of Azolla caroliniana. Plate counts indicated ca. 7,400±1,900 bacterial cells per mature leaf cavity or approximately 1 bacterial cell for every algal cell. No other type of bacterium was found in these cavities.
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    Antigenic differences between Anabaena azollae fresh from the Azolla fern leaf cavity and free-living cyanobacteria (1980)
    Springer
    Archives of microbiology 128 (1980), S. 126-129 
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    ISSN: 1432-072X
    Keywords: Fluorescent antibody staining ; Nitrogen fixation ; Symbiosis ; Anabaena azollae ; Azolla caroliniana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fluorescent antibody staining indicated differences in surface antigenicity in Anabaena azollae cells fresh from the leaf cavities of the fern, Azolla caroliniana, and algae which were isolated and subcultured from this fern. Such results suggest that either changes in antigenicity occur in this phycobiont during culturing or that isolation selects for an antigenically different mutant strain capable of in vitro growth.
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    The uptake and hydrolysis of disaccharides by fast-and slow-growing species of Rhizobium (1981)
    Springer
    Archives of microbiology 129 (1981), S. 238-239 
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    ISSN: 1432-072X
    Keywords: Rhizobium ; Disaccharide ; Bacteroid ; Transport ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Slow growing strains of rhizobia appear to lack both uptake systems and catabolic enzymes for disaccharides. In the fast-growing strains of rhizobia there are uptake mechanisms and catabolic enzymes for disaccharide metabolism. In Rhizobium leguminosarum WU 163 and WU235 and R. trifolii WU290, sucrose and maltose uptake appears to be constitutive whereas in R. meliloti WU60 and in cowpea Rhizobium NGR234 uptake of these disaccharides is inducible. There is evidence that there are at least two distinct disaccharide uptake systems in fast-growing rhizobia, one transporting sucrose, maltose and trehalose and the other, lactose. Disaccharide uptake is via an active process since uptake is inhibited by azide, dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone but not by arsenate. Bacteroids of R. leguminosarum WU235 and R. lupini WU8 are unable to accumulate disaccharides.
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    Regulation of nitrogenase messenger RNA synthesis and stability in Klebsiella pneumoniae (1981)
    Springer
    Archives of microbiology 130 (1981), S. 38-43 
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    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Gene expression ; Regulation ; Messenger RNA ; Transcription ; Klebsiella pneumoniae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogenase messenger RNA synthesis in Klebsiella pneumoniae was determined by labelling cells with (3H)uracil and isolating total RnA, which was then hybridized to filterbound recombinant plasmid pSA30 DNA carrying the nitrogenase structural genes nifH, D, and K. Derepression of nitrogenase mRNA starts 1.5 h before the onset of nitrogenase activity (as measured by acetylene reduction). Exposure of nif-derepressed cultures to either NH 4 + , air, or high temperatures (39° C) results in a rapid decrease of the synthesis rates both of nitrogenase mRNA and nitrogenase polypeptides. Nitrogenase mRNA is remarkably stable. After blocking transcription with rifampicin, hybridizable and actively translatable nitrogenase mRNA survives with an average half-life of 18 min. Half-lives are considerably shorter when rifampicin-inhibited cultures are simultaneously shifted to conditions which are non-permissive for nitrogenase synthesis, pointing to some posttranscriptional influence on nitrogenase mRNA stability. In all experiments performed there was no evidence for uncoupling of nitrogenase mRNA synthesis from nitrogenase mRNA translation, indicating that nitrogenase synthesis is regulated solely by transcriptional control.
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    Organisation of nodulation and nitrogen fixation genes on a Rhizobium trifolii symbiotic plasmid (1984)
    Springer
    Archives of microbiology 139 (1984), S. 151-157 
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    ISSN: 1432-072X
    Keywords: Rhizobium trifolii ; Symbiosis ; Nodulation ; Nitrogen fixation ; Symbiotic genes ; Reiterated sequences ; Plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A Rhizobium trifolii symbiotic plasmid specific gene library was constructed and the physical organisation of regions homologous to nifHDK, nifA and nod genes was determined. These symbiotic gene regions were localised to u 25 kb region on the sym-plasmid, pPN1. In addition four copies of a reiterated sequence were identified on this plasmid, with one copy adjacent to nifH. No rearrangement of these reiterated sequences was observed between R. trifolii bacterial and bacteroid DNA. Analysis of a deletion derivative of pPN1 showed that these sequences were spread over a 110 kb region to the left of nifA.
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    Interactions between cyanobacterium and fungus during 15N2-incorporation and metabolism in the lichen Peltigera canina (1983)
    Springer
    Archives of microbiology 134 (1983), S. 136-142 
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    ISSN: 1432-072X
    Keywords: Ammonia assimilation ; Lichen symbioses ; Nitrogen fixation ; 15N kinetics ; Peltigera canina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On following N2-incorporation and subsequent metabolism in the lichen Peltigera canina using 15N as tracer, it was found, over a 30 min period, that greatest initial labelling was into NH 4 + followed by glutamate and the amide-N of glutamine. Labelling of the amino-N of glutamine, aspartate and alanine increased slowly. Pulse-chase experiments using 15N confirmed this pattern. On inhibiting the GS-GOGAT pathway using l-methionine-dl-sulphoximine and azaserine, 15N enrichment of glutamate, alanine and aspartate continued although labelling of glutamine was undetectable. From this and enzymic data, NH 4 + assimilation in the P. canina thallus appears to proceed via GS-GOGAT in the cyanobacterium and via GDH in the fungus; aminotransferases were present in both partners. The cyanobacterium assimilated 44% of the 15N2 fixed; the remainder was liberated almost exclusively as NH 4 + and then assimilated by fungal GDH.
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    RNA polymerase from Rhizobium japonicum (1983)
    Springer
    Archives of microbiology 135 (1983), S. 103-109 
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    ISSN: 1432-072X
    Keywords: RNA polymerase ; Transcription ; Nitrogen fixation ; Symbiosis ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA-dependend RNA polymerase (EC 2.7.7.6) from Rhizobium japonicum was purified. The subunit structure was found to be ββ′α2σ, with the following apparent molecular weights determined by electrophoresis: M r (β and β') 150,000 each, M r (σ) 96,000, M r (α) 40,000, M r (holoenzyme) 490,000, M r (core enzyme) 380,000. The recovery of σ was 28%. RNA polymerase from aerobically grown R. japonicum cells and from nitrogen-fixing cells have the same electrophoretic properties suggesting that no chemical modification of the enzyme occurs when cells undergo this metabolic differentiation. The enzyme is Mg2+-dependent, rifampicin-sensitive, and has optimal activity at alkaline pH (8–10) and at 35–40° C. It binds strongly to bacteriophage T7 promoters, weakly to antibiotic resistance genes, and not at all to cloned R. japonicum nif DNA. Preliminary in vitro transcription experiments, including nif DNA as template, revealed that additional factors may be required for selective transcription from promoters.
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    Nitrogen metabolism in Xanthobacter H4-14 (1983)
    Springer
    Archives of microbiology 136 (1983), S. 219-221 
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    ISSN: 1432-072X
    Keywords: Xanthobacter ; Nitrogen fixation ; Oxygen sensitivity ; Nitrogen metabolism ; Glutamine synthetase ; Glutamate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract N2-fixation was investigated in the chemoautotrophic hydrogen bacterium Xanthobacter H4-14. N2-fixing batch cultures of this organism could only be grown at pO2 values of around 0.02 bar, and in continuous culture dissolved oxygen tensions above 16 μM were found to inhibit N2-fixation. Xanthobacter H4-14 utilized a variety of amino acids, nitrate and ammonia as nitrogen sources. Cell-free extracts from steady-state continuous cultures of ammonia grown, nitrate grown and N2-fixing Xanthobacter were assayed for the presence of ammonia assimilation enzymes. No alanine dehydrogenase or glutamate dehydrogenase activity was detected. Ammonia was assimilated exclusively via the glutamine synthetase/glutamate synthase pathway, irrespective of the extracellular concentration of ammonia.
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    Nitrogen fixation associated with a hotspring green alga (1980)
    Springer
    Archives of microbiology 124 (1980), S. 161-167 
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    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Photosynthesis ; Green alga ; Chl a and b ; DCMU ; Light and O2 dependency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A unicellular alga which can grow in the light without a combined nitrogen source was isolated from a hot spring. The cells were almost spherical, usually 5–10 μm in diameter. Absorption spectra of the watersoluble pigments and of the acetone-extracted ones revealed the existence of chlorophyll a and b and the absence of phycobilins. Thin sections examined by electron microscopy revealed an eukaryotic organization with features typical of the coccoid green algae (the Chlorococcales). Cells divided by internal cytokinesis and subsequent liberation of daughter cells from the parental wall, in a way similar to Chlorella. The alga reduced acetylene to ethylene and incorporated 15N2 into cell protoplasm when incubated in a low oxygen atmosphere. Nitrogenase activity was light-dependent, microaerophilic and thermophilic. Although the association of symbiotic nitrogen fixing prokaryotes with the cells may still be possible, any such organisms have not so far been detected.
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    Expression of klebsiella his and nif genes in serratia marcescens, Erwinia herbicola and Proteus mirabilis (1980)
    Springer
    Archives of microbiology 127 (1980), S. 115-118 
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    ISSN: 1432-072X
    Keywords: Proteus mirabilis ; Serratia marcescens ; Erwinia herbicola ; Nitrogen fixation ; nif genes ; his genes ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plasmid pRD1, an R plasmid of the P incompatibility group which carries his and nif genes from Klebsiella pneumoniae in addition to drug resistance markers derived from RP4, was transferred to His- mutants of Serratia marcescens, Erwinia herbicola and Proteus mirabilis. His+ transconjugants were obtained at low but different frequencies according to recipient genus. Transconjugants all acquired the drug resistance, and were Nif+ in S. marcescens and E. herbicola, having acetylene-reducing activities of the same order of magnitude as the parent K. pneumoniae and fixing 15N2. No evidence for nif expression in P. mirabilis transconjugants was obtained though the nif genes were present.
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    Mutants of Rhizobium japonicum defective in nodulation (1982)
    Springer
    Archives of microbiology 132 (1982), S. 219-224 
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    ISSN: 1432-072X
    Keywords: Rhizobium ; Nitrogen fixation ; Nodules ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several mutants defective in nodulation were isolated from Rhizobium japonicum strains 3I1b110 and 61A 76. Mutants of class I do not form nodules after incubation with soybean [Glycine max (L.) Merrill] for 17 days, but will do so by 28 days. When host plants other than G. max are infected with several of these strains, there is no detectable difference in the time of nodulation or size of nodules as compared to the wild type. Two mutants of class I (i. e., SM1 and SM2) have been shown previously to be altered in the lipopolysaccharide portion of their cell wall. Mutants of class II are not slow to nodulate but form fewer nodules than the wild type on all the host plants tested. Mutants of class III are unable to form nodules. Some bacteriophage-resistant mutants, altered in cell surface structure, fall into this class. Two mutants of class III do not bind to soybean roots.
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    Nitrogen fixation and nitrate utilization by marine and freshwater Beggiatoa (1982)
    Springer
    Archives of microbiology 133 (1982), S. 172-177 
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    ISSN: 1432-072X
    Keywords: Beggiatoa ; Nitrogen fixation ; Acetylene reduction ; Nitrate assimilation ; Microaerobic ; Isolation of marine strains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four newly isolated marine strains of Beggiatoa and five freshwater strains were tested for nitrogen fixation in slush agar medium. All strains reduced acetylene when grown microaerobically in media containing a reduced sulfur source and lacking added combined nitrogen. The addition of 2 mmol N, as nitrate or ammonium salts, completely inhibited this reduction. Although not optimized for temperature or cell density, acetylene reduction rates ranged from 3.2 to 12 nmol·mg prot-1 min-1. Two freshwater strains did not grow well or reduce acetylene in medium lacking combined nitrogen if sulfide was replaced by thiosulfate. Two other strains grew well in liquid media lacking both combined nitrogen and reduced sulfur compounds but only under lowered concentrations of air. All freshwater strains grew well in medium containing nitrate as the combined nitrogen source. Since they did not reduce acetylene under these conditions, we infer that they can assimilate nitrate.
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    The role of formate metabolism in nitrogen fixation in Rhizobium Spp. (1982)
    Springer
    Archives of microbiology 133 (1982), S. 312-317 
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    ISSN: 1432-072X
    Keywords: Rhizobium japonicum ; Rhizobium leguminosarum ; Formate metabolism ; Formate dehydrogenase ; Nitrogen fixation ; Nitrogenase ; Bacteroids ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Formate metabolism supported nitrogen-fixation activity in free-living cultures of Rhizobium japonicum. However, formate0dependent nitrogense activity was observed only in the presence of carbon sources such as glutamate, ribose or aspartate which by themselves were unable to support nitrogenase activity. Formate-dependent nitrogenase activity was not detected in the presence of carbon sources such as malate, gluconate or glycerol which by themselves supported nitrogenase activity. A mutant strain of R. japonicum was isolated that was unable to utilise formate and was shown to lack formate dehydrogenase activity. This mutant strain exhibited no formate-dependent nitrogenase activity. Both the wild-type and mutant strains nodulated soybean plants effectively and there were no significant differences in the plant dry weight or total nitrogen content of the respective plants. Furthermore pea bacteroids lacked formate dehydrogenase activity and exogenously added formate had no stimulatory effect on the endogenous oxygen uptake rate. The role of formate metabolism in symbiotic nitrogen fixation is discussed.
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    L-Methionine-SR-sulfoximine as a probe for the role of glutamine synthetase in nitrogenase switch-off by ammonia and glutamine in Rhodopseudomonas palustris (1983)
    Springer
    Archives of microbiology 134 (1983), S. 17-22 
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    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Nitrogenase regulation ; Glutamine synthetase ; Methionine suofoximine ; Rhodospirillaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methionine sulfoximine (MSX), an irreversible inhibitor of glutamine synthetase of Rhodopseudomonas palustris restored nitrogenase activity to cells in which nitrogenase had been completely inhibited by ammonia switch-off. After addition of MSX, there was a lag period before nitrogenase activity was fully restored. During this lag, glutamine synthetase activity progressively decreased, and near the time of its complete inhibition, nitrogenase activity resumed. Nitrogenase switch-off by ammonia thus required active glutamine synthetase. Glutamine itself caused nitrogenase inhibition whose reversal by MSX depended on the relative ratio of MSX to glutamine. Unlike ammonia, glutamine inhibited nitrogenase under conditions where glutamine synthetase activity was absent. This indicates that glutamine is the effector molecule in nitrogenase switch-off, for instance by interacting with the enzymatic system for Fe protein inactivation. The effects of glutamine and MSX were also dependent on the culture age. Possible explanation for this and for the competitive effects are a common binding site within the regulatory apparatus for nitrogenase, or, in part, within a common transport system. Some observations with MSX were extended to Rhodopseudomonas capsulata and agreed with those in R. palustris.
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    Whole cell respiration and nitrogenase activities in Azotobacter vinelandii growing in oxygen controlled continuous culture (1983)
    Springer
    Archives of microbiology 134 (1983), S. 68-72 
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    ISSN: 1432-072X
    Keywords: Azotobacter vinelandii ; Continuous culture ; Oxygen control ; Nitrogen fixation ; Respiratory protection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Azotobacter vinelandii strain OP was grown in continuous culture at various dissolved oxygen concentrations of air (100% air saturation of the medium=225 ±14 μM O2). Sucrose was added as carbon source and either dinitrogen or ammonia as nitrogen sources. Irrespective of the nitrogen source steady state cultures showed the following general responses with dissolved oxygen concentrations increasing from about 1% to 30% air saturation: (i) cell protein levels, (ii) the amount of cell protein formed per sucrose consumed as well as (iii) nitrogenase activity decreased by at least a factor of two while (iv) cellular respiration increased. At higher oxygen concentrations the parameters changed only slightly, if at all. Increasing the sucrose concentration in the inflowing medium (s R) from 3 g/l to 15 g/l increased the total level of cellular respiration with nitrogen-fixing cultures but was more pronounced with ammonium-assimilating cultures. With nitrogen-fixing cultures cell protein levels increased five-fold while the ratio of protein formed per sucrose consumed as well as cellular nitrogenase activity remained unaffected. With ammonium-assimilating cultures the cell protein level was only doubled and the level of cell protein formed per sucrose consumed was decreased at the higher s R. Increasing the dilution rate at a constant oxygen concentration of 45% air saturation resulted in an almost parallel increase of both cellular respiratory and nitrogenase activity at low and moderate dilution rates. At high dilution rates nitrogenase activity increased steeply over the respiratory activity. Nitrogen-fixing cultures adapted to various oxygen concentrations were subjected to oxygen stress by increasing the oxygen concentration for 7 min. In all cases, this resulted in a complete inhibition (‘switch-off’) of nitrogenase activity. Upon restoration of the original oxygen concentration nitrogenase activity returned to a decreased level. The discussion arrives at the conclusion that some of the results are incompatible with the concept of respiratory protection of nitrogenase.
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    Involvement of ammonium metabolism in the nitrate inhibition of nitrogen fixation in Anabaena sp. strain ATCC 33047 (1983)
    Springer
    Archives of microbiology 136 (1983), S. 81-83 
    Details
    ISSN: 1432-072X
    Keywords: Ammonia production ; Anabaena ; Cyanobacteria ; Nitrate reductase ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the filamentous heterocystous cyanobacterium Anabaena sp. strain ATCC 33047 dinitrogen fixation and nitrate reduction are mutually exclusive processes. Nitrate promotes nitrate reductase synthesis and represses nitrogenase formation. Inhibition of ammonium assimilation by l-methionine-d,l-sulfoximine (MSX) alleviates the repressive effect of nitrate on nitrogenase synthesis, thus indicating that the nitrate effect is indirect through metabolites generated from the ammonium derived from nitrate reduction. In MSX-treated cells both nitrate reduction and dinitrogen fixation take place simultaneously, although at different sites of the filament, without any apparent competition for the required reducing power. The MSX-treated Anabaena cells generate ammonium from both nitrate and dinitrogen, simultaneously.
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    Denitrification by Azospirillum brasilense Sp 7 (1984)
    Springer
    Archives of microbiology 138 (1984), S. 212-216 
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    ISSN: 1432-072X
    Keywords: Denitrification ; Nitrate respiration ; Nitrous oxide reduction ; Nitrogen fixation ; Azospirillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrous oxide reduction can consistently be demonstrated with high activities in cells of Azospirillum brasilense Sp 7 which are grown anaerobically in the presence of low amounts of nitrite. Azospirillum can even grow anaerobically with nitrous oxide in the absence of any other respiratory electron acceptor. Nitrous oxide reduction by Azospirillum is inhibited by acetylene, amytal and weakly by carbon monoxide. Azospirillum converts nitrous oxide to molecular nitrogen without the formation of ammonia. The cells must, therefore, be supplied with ammonia from nitrogen fixation during anaerobic growth with nitrous oxide. When no other nitrogen compound besides nitrous oxide is available in the medium, the bacteria synthesize nitrogenase from protein reserves in about 2 h. Nitrogenase synthesis is blocked by chloramphenicol under these conditions. In contrast, the addition of nitrate or nitrite to the medium represses the synthesis of nitrogenase. Nitrous oxide reduction by Azospirillum and other microorganisms is possibly of ecological significance, because the reaction performed by the bacteria may remove nitrous oxide from soils.
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    Transformations of inorganic nitrogen by Azospirillum spp. (1981)
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    Archives of microbiology 130 (1981), S. 96-100 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Nitrate respiration ; Denitrification ; Assimilatory nitrate reduction ; Dissimilatory nitrate reduction ; Acetylene reduction ; Azospirillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Azospirillum spp. participate in all steps of the nitrogen cycle except nitrification. They can fix molecular nitrogen and perform assimilatory nitrate reduction and nitrate respiration. Culture conditions have been defined under which nitrate is used both as terminal respiratory electron acceptor and as nitrogen source for growth. Nitrate and, possibly to a very limited extent, nitrite, but not sulfate, iron or fumarate support anaerobic respiration. Under anaerobic conditions, nitrate can also supply energy for nitrogen fixation but without supporting growth. Nitrate-dependent nitrogenase activity lasts only for 3–4 h until the enzymes of assimilatory nitrate reduction are synthesized. Nitrite accumulates during this period and inhibits nitrogenase activity at concentrations of about 1 mM.
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    Glutathione reductase activity in heterocysts and vegetative cells of the cyanobacterium Nostoc muscorum (1984)
    Springer
    Archives of microbiology 140 (1984), S. 215-217 
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    ISSN: 1432-072X
    Keywords: Glutathione reductase ; Cyanobacteria ; Nostoc muscorum ; O2 protection ; Glutathione ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glutathione reductase activity was detected and characterized in heterocysts and vegetative cells of the cyanobacterium Nostoc muscorum. The activity of the enzyme varied between 50 and 150 nmol reduced glutathione· min-1·mg protein-1, and the apparent Km for NADPH was 0.125 and 0.200 mM for heterocysts and vegetative cells, respectively. The enzyme was found to be sensitive to Zn+2 ions, however, preincubation with oxidized glutathione rendered its resistance to Zn+2 inhibition. Nostoc muscorum filaments were found to contain 0.6–0.7mM glutathione, and it is suggested that glutathione reductase can regenerate reduced glutathione in both cell types. The combined activity of glutathione reductase and isocitrate dehydrogenase in heterocysts was as high as 18 nmol reduced glutathione·min-1·mg protein-1. A relatively high superoxide dismutase activity was found in the two cell types; 34.2 and 64.3 enzyme units·min-1·mg protein-1 in heterocysts and vegetative cells, respectively. We suggest that glutathione reductase plays a role in the protection mechanism which removes oxygen radicals in the N2-fixing cyanobacterium Nostoc muscorum.
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    Interaction of respiratory and photosynthetic electron transport in Anabaena variabilis Kütz. (1982)
    Springer
    Archives of microbiology 132 (1982), S. 333-337 
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    ISSN: 1432-072X
    Keywords: Anabaena variabilis Kütz ; 14C-prelabeled blue-green algae ; Interaction respiration/photosynthesis ; CO2 exchange ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Prelabeled Anabaena variabilis Kütz. evolves 14CO2 in the light with KCN and DCMU (2,4-dichlorophenyl-1,1-dimethylurea) present, comparable to the dark control without inhibitors added. Double-reciprocal plots of CO2 release vs. light intensity with either KCN or KCN+DCMU present result in two straight lines intersecting at the ordinate. Apparently, reducing equivalents originating from carbohydrate catabolism are channeled into the photosynthetic electron-transport chain, competing for electrons from photosystem II. Under these conditions, the CO2 release is accompanied by a light-dependent oxygen uptake, presumably due to oxygen-reducing photosystem-I activity while ribulose-bisphosphate carboxylase is inhibited by KCN. Comparing nine blue-green algae it was shown that only nitrogen-fixing species release substantial amounts of CO2 in the light with KCN or KCN+DCMU present. This release is particularly obvious with Anabaena variabilis Kütz. under nitrogen-fixing conditions, but small when the alga is grown with combined nitrogen. We conclude that nitrogen-fixing species share a common link between respiratory and photosynthetic electron transport. The physiological role may be electron supply of nitrogenase by photosystem I.
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    Nitrogen metabolism inRhodopseudomonas globiformis (1982)
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    Archives of microbiology 133 (1982), S. 6-10 
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    ISSN: 1432-072X
    Keywords: Rhodospirillaceae ; Rhodopseudomonas globiformis ; Nitrogen metabolism ; Nitrogen fixation ; Glutamine synthetase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhodopseudomonas globiformis strain 7950 grew with a variety of amino acids, urea, or N2 as sole nitrogen sources. Cultures grown on N2 reduced acetylene to ethylene; this activity was absent from cells grown on nonlimiting NH 4 + . Glutamate dehydrogenase could not be detected in extracts of cells of strain 7950, although low levels of an alanine dehydrogenase were present. Growth ofR. globiformis on NH 4 + was severely inhibited by the glutamate analogue and glutamine synthetase inhibitor, methionine sulfoximine. High levels of glutamine synthetase (as measured in the γ-glutamyl transferase assay) were observed in cell extracts of strain 7950 regardless of the nitrogen source, although N2 and amino acid grown cells contained somewhat higher glutamine synthetase contents than cells grown on excess NH 4 + . Levels of glutamate synthase inR. globiformis were consistent with that reported from other phototrophic bacteria. Both glutamate synthase and alanine dehydrogenase were linked to NADH as coenzyme. We conclude thatR. globiformis is capable of fixing N2, and assimilates NH 4 + primarily via the glutamine synthetase/glutamate synthase pathway.
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    Chroococcus S24 and Chroococcus N41 (cyanobacteria): morphological, biochemical and genetic characterization and effects of water stress on ultrastructure (1983)
    Springer
    Archives of microbiology 135 (1983), S. 81-90 
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    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Ultrastructure ; Nitrogen fixation ; Water stress ; Taxonomy ; DNA ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two strains of desiccation-tolerant coccoid cyanobacteria, Chroococcus S24, a marine form, and Chroococcus N41, a cryptoendolith isolated from a hot-desert rock, have been characterized. The mol % DNA base compositions of the strains are 47.1 and 48.9% respectively. Plasmid DNA was not detected in either strain. The pigment contents and nutritional characteristics of the strains are identical. Both lack phycoerythrinoid pigments and, in culture, behave as slow-growing halotolerant marine forms with elevated requirements for Na+, Cl−, Mg2+ and Ca2+. Sucrose was the only carbon source of those tested that supported photoheterotrophic growth. Each strain synthesizes nitrogenase under anaerobic conditions but not in air. Morphologically the two strains are indistinguishable. They are considered to be independent isolates of the same cyanobacterial species. Chroococcus N41 was studied in detail with the electron microscope. When brought to equilibrium at matric water potentials of-168 MPa and lower (to-673 MPa=c0.12a w) the protoplast shrinks, but the cells maintain the same size and diameter as those at-2,156 kPa (MN medium; control); the sheath expands and remains attached to the cell wall outer membrane by fibrils. The cell wall, cell membrane, thylakoid membranes, cyanophycin granules and carboxysomes appeared intact in desiccated cells.
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    The interaction of nitrogen and carbon monoxide with certain ions and neutral species (1982)
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    Theoretical chemistry accounts 60 (1982), S. 579-587 
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    ISSN: 1432-2234
    Keywords: Nitrogen fixation ; Nitrogen complexes ; Carbon monoxide complexes ; Electronic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract MNDO method is used to study the interaction of nitrogen and carbon monoxide molecules with a proton, hydrogen atom, hydride ion, hydrogen molecule ion and hydrogen molecule. Predicted geometries and heats of reaction of different complexes are presented. The wave functions are analyzed in terms of ground state charge distributions and overlap populations. Electronic effects accompanying complexation are also discussed.
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    Nitrogen nutrition and the development and senescence of nodules on cowpea seedlings (1984)
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    Planta 162 (1984), S. 316-326 
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    ISSN: 1432-2048
    Keywords: Nitrogen fixation ; Nodule development ; Senescence (nodules) ; Vigna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cowpea (Vigna unguiculata (L.) Walp cv. Vita 3) seedlings inoculated with Rhizobium strain CB756 were cultured with their root systems maintained in air or in Ar: O2 (80:20, v/v) during early nodule development (up to 24 d after sowing). Compared with those in air, seedlings in Ar:O2 showed progressive N deficiency with inhibited shoot growth, reduced ribulose-1,5-bisphosphate carboxylase and total protein levels and loss of chlorophyll in the leaves. Nodule initiation, differentiation of infected and uninfected nodule tissues and the ultrastructure of bacteriod-containing cells were similar in the air and Ar: O2 treatments up to 16 d after sowing. Thereafter the Ar: O2 treatment caused cessation of growth and development of nodules, reduced protein levels in bacteroids and nodule plant cells, and progressive degeneration of nodule ultrastructure leading to premature senescence of these organs. Provision of NO 3 - (0.1–0.2 mM) to Ar: O2-grown seedlings overcame the abovementioned consequences of N2 deficiency on nodule and plant growth, but merely delayed the degenerative effects of Ar: O2 treatment on nodule structure and senescence. Treatment of Ar: O2-grown seedlings with NO 3 - greatly increased the protein level of nodules but the increase was largely restricted to the plant cell fraction as opposed to the bacteroids. By contrast, NO 3 - treatment of air-grown seedlings increased protein of bacteroid and host nodule fractions to the same relative extents when compared with air-grown plants not supplemented with NO 3 - . These findings, taken together with studies of the distribution of N in nodules of symbiotically effective plants grown from 15N-labeled seed, indicate that direct incorporation of fixation products by bacteroids may be a critical feature in the establishment and continued growth of an effective symbiosis in the cowpea seedling.
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    Appearance of a novel form of plant glutamine synthetase during nodule development in Phaseolus vulgaris L. (1983)
    Springer
    Planta 157 (1983), S. 254-258 
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    ISSN: 1432-2048
    Keywords: Glutamine synthetase ; Leghaemoglobin ; Nitrogenase ; Nitrogen fixation ; Phaseolus ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activities of glutamine synthetase (GS), nitrogenase and leghaemoglobin were measured during nodule development in Phaseolus vulgaris infected with wild-type or two non-fixing (Fix-) mutants of Rhizobium phaseoli. The large increase in GS activity which was observed during nodulation with the wild-type rhizobial strain occurred concomitantly with the detection and increase in activity of nitrogenase and the amount of leghaemoglobin. Moreover, this increase in GS was found to be due entirely to the appearance of a novel form of the enzyme (GSn1) in the nodule. The activity of the form (GSn2) similar to the root enzyme (GSr) remained constant throughout the experiment. In nodules produced by infection with the two mutant strains of Rhizobium phaseoli (JL15 and JL19) only trace amounts of GSn1 and leghaemoglobin were detected.
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    Two new species and one new variety of Agaricales from central Honshu, Japan (2000)
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    Mycoscience 41 (2000), S. 15-23 
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    ISSN: 1618-2545
    Keywords: Agaricales ; Clitocybe trogioides var.odorifera ; Gerronema nemorale ; Psathyrella cineraria ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two new species and one new variety of Agaricales are described and illustrated from central Honshu, Japan:Clitocybe trogioides var.odorifera var. nov. (subgenusCystoclitus sectionCystoclitus), forming white, infundibuliform basidiomata, was collected from leaf litter in theQuercus-Pasania forests;Gerronema nemorale sp. nov. (sectionXanthophylla), forming small, olivaceous, omphalinoid basidiomata, was found on dead fallen twigs in theQuercus-Pasania forests;Psathyrella cineraria sp. nov. (subgenusMycophylla sectionArgillosporae), forming basidiomata covered by detersile, dark grey, fibrillose-squamulose veil, was found on decayed wood ofQuercus myrsinaefolia.
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    Diaporthe kyushuensis sp. nov., the teleomorph of the causal fungus of grapevine swelling arm in Japan, and its anamorphPhomopsis vitimegaspora (2000)
    Springer
    Mycoscience 41 (2000), S. 111-114 
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    ISSN: 1618-2545
    Keywords: Diaporthe kyushuensis ; grapevine swelling arm ; Phomopsis vitimegaspora ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diaporthe kyushuensis sp. nov. is described and named as the teleomorph of causal fungus of grapevine swelling arm. The anamorph of the fungus isPhomopsis vitimegaspora.
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    Cronartium orientale, sp. nov., segregation of the pine gall rust in eastern Asia fromCronartium quercuum (2000)
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    Mycoscience 41 (2000), S. 115-122 
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    ISSN: 1618-2545
    Keywords: distribution ; Pinus ; Quercus ; taxonomy ; Uredinales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Asian pine gall rust, which has hitherto been assigned toCronartium quercuum distributed in North America, is described asC. orientale, sp. nov. The spermogonial and aecial states occur on hard pines, and the uredinial and telial states occur on various oaks.Cronartium orientale has globose, almost hyaline basidiospores in contrast to the ellipsoid, yellow-orange ones of North AmericanC. quercuum s.l. Characteristics of the new rust species in morphology, DNA analysis, and host alternation are discussed.
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    A newLeptographium species associated withTomicus piniperda in south-western China (2000)
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    Mycoscience 41 (2000), S. 573-578 
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    ISSN: 1618-2545
    Keywords: China ; Leptographium ; morphology ; taxonomy ; Tomicus piniperda
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tomicus species (Coleoptera: Scolytidae) are serious pests of pines with a wide distribution in Europe, Asia and America. In Yunnan, south-western China,T. piniperda has destroyed more than 0.5 million ha ofPinus yunnanensis in the past 15 years. A blue stain fungus belonging to the genusLeptographium is associated with both the shoot-feeding and trunk-attacking stages of the beetle's life cycle. The fungus is morphologically similar to the anamorph ofOphiostoma crassivaginatum and toL. pyrinum, which are both characterised by short robust conidiophores and hyphae covered by a granular layer. Both these species have been isolated from conifers and are associated with insects. After comparing the fungus fromT. piniperda with similarLeptographium species, using light and scanning electron microscopy, we concluded that it represents a new taxon, which is described here asL. yunnanense sp. nov.
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    Novel ultrastructural observations of pea (Pisum sativum) root nodule cells by high-pressure freezing and propane-jet freezing techniques (2000)
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    Protoplasma 213 (2000), S. 55-66 
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    ISSN: 1615-6102
    Keywords: Endoplasmic reticulum ; High-pressure freezing ; Nitrogen fixation ; Rhizobium leguminosarum ; Propane-jet freezing ; Peribacteroid space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pea (Pisum sativum) root nodule cells infected by the diazotrophRhizobium leguminosarum have been well characterized by chemical fixation techniques. Propane-jet freezing and high pressure freezing were used in this study to compare rapidly frozen and chemically fixed pea root nodule cells. Cells that had been incubated in 2-(N-morpholino)ethanesulfonic acid buffer and frozen with the propane-jet freezer were better preserved than cells that had been chemically fixed or frozen with the high-pressure freezer. Rapidly frozen infected nodule cells showed that the rough endoplasmic reticulum had a high frequency of associations with the peribacteroid membrane and the infection thread. The peribacteroid space also varied in size depending on the method of preservation; however, it was most reduced in size and devoid of inclusions in the propane-jet frozen tissue. The biological significance of these observations is discussed.
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    Some observations on cell wall structure and taxonomy ofPhymatodocis nordstedtiana (Conjugatophyceae, Chlorophyta) (1981)
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    Plant systematics and evolution 138 (1981), S. 217-225 
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    ISSN: 1615-6110
    Keywords: Conjugatophyceae ; Desmidiales ; Phymatodocis nordstedtiana ; Cell wall ; pore apparatus ; taxonomy ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Filaments ofPhymatodocis nordstedtiana Wolle were isolated from a sample of a Texan lake. Cultures were established and examined by light and scanning electron (SEM) as well as transmission electron microscopy (TEM). It is shown that the pores apparent on light microscopical examination are not of the cosmaroid type as expected. TEM examination disclosed that they are similar to those found in the generaClosterium Ralfs andPenium Bréb. Furthermore, it could be demonstrated by light and SEM microscopy that the primary cell wall is shed during cell division. The remaining secondary cell wall of the mature cell consists of interwoven bands of parallel microfibrils. A conspicuous overlap of the semicell walls clearly denotes the isthmus region. The significance of these deviations unusual for desmids is discussed. Suggestions are made that the taxonomic position ofPh. nordstedtiana should be re-evaluated.
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    Chlamydomonas chlorococcoides nova spec., eine neue Art mit gelapptem Chloroplast (Volvocales, Chlorophyta) (1981)
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    Plant systematics and evolution 138 (1981), S. 115-120 
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    ISSN: 1615-6110
    Keywords: Volvocales ; Chlamydomonas ; Morphology ; reproduction ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlamydomonas chlorococcoides, a morphologically most interesting new species with a lobate chloroplast was isolated from soils of the island Lavsa (Adriatic Sea, Yugoslavia). Description, pictures and remarks on the reproduction are given.
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    Auxospore formation inLicmophora (Bacillariophyta) (1982)
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    Plant systematics and evolution 139 (1982), S. 289-294 
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    ISSN: 1615-6110
    Keywords: Bacillariophyta ; Pennatae ; Fragilariaceae ; Licmophora gracilis var.anglica ; Auxospore formation ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract InLicmophora gracilis var.anglica two auxospores are produced per pair of mother-cells, through the allogamic fusion of migratory and stationary gametes. Both active gametes are produced from the same mother-cell and hence both zygotes are formed in the other mother-cell. Pairing can occur between two stalked cells, or between a stalked cell and a detached cell; in the latter case the migratory gametes derive from the detached cell. The auxospores expand parallel to one another and to the apical axis of the donor mother-cell. Behavioural anisogamy of this kind, which may be termed thecis-type, seems to be characteristic of most araphid pennates and contrasts with thetrans-type exhibited byCymbella, Gomphonema and some other raphid taxa, where each mother-cell produces one migratory and one stationary gamete.
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    The delimitation and taxonomic position of the tropical African generaLeptactina andDictyandra (Rubiaceae) (1984)
    Springer
    Plant systematics and evolution 145 (1984), S. 105-118 
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    ISSN: 1615-6110
    Keywords: Rubiaceae ; Coffeeae ; Gardenieae ; Pavetteae ; Dictyandra ; Leptactina ; Tarenna ; Pavetta ; Dictyandra congolana sp. nova ; taxonomy ; morphology ; seed-coat ; palynology ; Flora of tropical Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The closely related African generaDictyandra andLeptactina are redelimited. The two genera are distinguished by long tubular corolla-tubes with included anthers (Leptactina) vs. much shorter tubes with exserted anthers (Dictyandra), rather than—as previously thought—presence or absence of multilocellate anthers. The discovery of a new species (Dictyandra congolana from the Congo and W-Zaire) confirms this. It can be concluded, especially from comparative morphological studies of fruits and seeds, thatDictyandra andLeptactina are related toPavetta, Tarenna, Ixora, etc., i.e. the group of genera in theCoffeeae s.l. with terminal inflorescences. It is proposed that the tribePavetteae be revived to accomodate those genera.
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    An ultrastructural comparison betweenSpermatozopsis andDunaliella (Chlorophyceae) (1984)
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    Plant systematics and evolution 146 (1984), S. 31-46 
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    ISSN: 1615-6110
    Keywords: Chlorophyceae ; Spermatozopsis ; Dunaliella ; D. salina ; Green flagellates ; ultrastructure ; taxonomy ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of the type species of the genusDunaliella, D. salina, has been reinvestigated in an attempt to clarify the relationships betweenDunaliella andSpermatozopsis. Dunaliella salina differs in the following ultrastructural characters fromSpermatozopsis (as exemplified byS. similis Preisig etMelkonian): presence of a distinctive surface coat covering the plasmalemma; presence of a prominent pyrenoid (with pairs of thylakoids partially entering the pyrenoid matrix); dictyosomes parabasal; endoplasmic reticulum closely underlying the plasmalemma around most of the cell; contractile vacuoles absent; cell form ovoid to elongated and not spirally twisted; mitochondrial profiles near the flagellar apparatus. Differences in the ultrastructure of the flagellar apparatus: basal body angle more or less fixed; distal connecting fibre cross-striated; system II fibre (rhizoplast) present, associated with mitochondrial profile; system I fibre underlying two-stranded microtubular root; mating structure present. These ultrastructural differences justify distinction between the two taxa at generic level. The problematical status of “freshwater” species ofDunaliella is briefly discussed.
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    A light and electron microscopical study of the green flagellateSpermatozopsis similis spec. nova (1984)
    Springer
    Plant systematics and evolution 146 (1984), S. 57-74 
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    ISSN: 1615-6110
    Keywords: Chlorophyceae ; Spermatozopsis similis ; Green flagellate ; new species ; algal culture ; electron microscopy ; taxonomy ; phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The green flagellateSpermatozopsis similis spec. nova has been studied in culture by light and electron microscopy. The flagellate bears two flagella, is naked and has a characteristic crescent and spirally twisted cell shape. The two flagella are of subequal length, each with a prominent hair-point. Each cell contains two contractile vacuoles, a single chloroplast with an anterior eyespot but lacking a pyrenoid, an anteriorly located nucleus, a single dictyosome associated with the posterior end of the nucleus, a single mitochondrion posterior to the nucleus and associated with a small microbody, some conspicuous vacuoles, and a greater number of secondary cytoskeletal microtubules which probably are responsible for maintaining the peculiar shape of this species. SinceS. similis in culture is only biflagellate, it cannot be accommodated within the quadriflagellate, but otherwise very similar speciesS. exsultans. Spermatozopsis similis is compared with other green flagellates and is shown to share common ultrastructural characters withChlamydomonas-type green algae.
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    Spiniferomonas septispina andS. enigmata, two new algal species confusing the distinction betweenSpiniferomonas andChrysosphaerella (Chrysophyceae) (1984)
    Springer
    Plant systematics and evolution 148 (1984), S. 103-117 
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    ISSN: 1615-6110
    Keywords: Algae ; Chrysophyceae ; Spiniferomonas septispina sp. n. ; S. enigmata sp. n. ; Chrysosphaerella ; Morphology ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two new species of non-colonial silica-scaled chrysophytes were discovered in Ontario and were assigned to the genusSpiniferomonas (Chrysophyceae) owing to their solitary cell habit. Scale structure in the two new species is distinctive but includes features common to bothSpiniferomonas andChrysosphaerella. The use of scale structure as the main diagnostic feature to distinguish the two genera is no longer acceptable. A more expedient separation of the two genera based on cell habit (solitary vs. colonial) is proposed and includes the transfer ofChrysospharella salina Birch-Andersen andChrysosphaerella coronacircumspina Wujek & Kristiansen to the genusSpiniferomonas as new combinations. The proposed revision is consistent with existing generic circumscriptions of other ochromonadalean forms with either solitary or colonial cell habit.
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    Über einen intrazellulären Parasiten beiCryptomonas (Cryptophyceae), II. (1984)
    Springer
    Plant systematics and evolution 148 (1984), S. 165-167 
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    ISSN: 1615-6110
    Keywords: Cryptophyceae ; Bodonaceae ; Proteromonas steinii sp. n. ; Cryptomonas spp. div. ; Intracellular parasite ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new intracellular parasite inCryptomonas spp. div. previously known is described asProteromonas steinii spec. nova. The flagellate (infectious) stage isBodo-like, with a distinct kinetoplast. The immobile parasitic stage occurs in the cells of Cryptomonads as a multinucleate trophocyst with a thin mucilage envelope (pseudocyst), while the hypnocyst is uninucleate, walled and bearing two horned projections.
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    Species, Demes, and the Omega Taxonomy: Gilmour and The NewSystematics (2000)
    Springer
    Biology and philosophy 15 (2000), S. 349-388 
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    ISSN: 1572-8404
    Keywords: cline ; definition ; deme ; evolutionary synthesis ; experimental taxonomy ; J. Heslop-Harrison ; J.S. Huxley ; J.S.L. Gilmour ; nominalism ; systematics ; Systematics Association ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract The word ``deme'' was coined by the botanists J.S.L. Gilmour and J.W.Gregor in 1939, following the pattern of J.S. Huxley's ``cline''. Its purposewas not only to rationalize the plethora of terms describing chromosomaland genetic variation, but also to reduce hostility between traditionaltaxonomists and researchers on evolution, who sometimes scorned eachother's understanding of species. A multi-layered system of compoundterms based on deme was published by Gilmour and J. Heslop-Harrison in1954 but not widely used. Deme was adopted with a modified meaning byzoologists leading the evolutionary synthesis – Huxley, Simpson, Wright,and Mayr. Connections are shown between Gilmour's ideas around definingthe deme, his role in founding the Systematics Association, and his chapter``Taxonomy and Philosophy'' in the book The New Systematics. Thishistorical episode raises questions about the role of carefully-definedwords in scientific practice.
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    A new variety ofCortinarius elatior from Japan (2000)
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    Mycoscience 41 (2000), S. 87-89 
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    ISSN: 1618-2545
    Keywords: Cortinarius elatior var.albipes ; Cortinarius Sect.Defibulati ; new variety ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cortinarius elatior var.albipes var. nov., found in the deciduous forest is described and illustrated. It is distinguished from the type variety by having a white stipe and longer spores. The differences betweenCortinarius elatior var.albipes and similar taxa are briefly discussed.
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    Ceratostomella hyalocoronata, a new pyrenomycete from a stream in southern China (2000)
    Springer
    Mycoscience 41 (2000), S. 167-169 
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    ISSN: 1618-2545
    Keywords: East Asia ; freshwater fungi ; taxonomy ; tropical mycology ; Xylariales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ceratostomella hyalocoronata is described and illustrated as a new species from old decaying wood immersed in a stream in Guangdong Province, southern China. It is compared toC. hyalostoma, a temperate terrestrial species.
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    Three new marine ascomycetes from driftwood in Australia sand dunes (2000)
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    Mycoscience 41 (2000), S. 379-388 
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    ISSN: 1618-2545
    Keywords: arenicolous ; marine fungi ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Caryospora australiensis sp. nov.,Platystomum scabridisporum sp. nov. andSavoryella melanospora sp. nov. are described from driftwood collected from a sand dune at Rye, on the Mornington Peninsula Nature Park, Victoria, Australia. These species are compared with other taxa in these and related genera.
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    Two underscribed heterobasidiomycetes from Ontario (2000)
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    Mycoscience 41 (2000), S. 371-377 
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    ISSN: 1618-2545
    Keywords: Platygloea ; Platygloeales ; Sigmogloea ; taxonomy ; Tremellales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of two heterobasidiomycetous species, collected in Ontario and studied respectively by H. S. Jackson and R. F. Cain, are described as new; they arePlatygloea jacksonii andSigmogloea tremelloidea. P. jacksonii is characterized by small basidia and basidiospores and by sympodially developing conidia.Sigmogloea tremelloidea is an anomalous taxon with cylindric, mostly transversely septate (“auricularioid”) basidia, but some features suggest a possible relationship to the Tremellales.
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    Cortinarius purpurascens var.largusoides andCortinarius herpeticus var.fageticola new to Japan (2000)
    Springer
    Mycoscience 41 (2000), S. 407-410 
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    ISSN: 1618-2545
    Keywords: Cortinarius purpurascens var.largusoides ; Cortinarius herpeticus var.fageticola ; Cortinarius Sect.Scauri ; mycoflora ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two species ofCortinarius Sect.Scauri collected in forests ofQuercus serrata andQ. mongolica var.grosseserrata, Q. serrata andFagus crenata, orQ. mongolica var.grosseserrata andF. crenata in Niigata prefecture were identified asCortinarius purpurascens var.largusoides andC. herpeticus var.fageticola, new to Japan. Macro- and microscopical descriptions of each species are given.
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    Intraspecific Variation in the Vocalizations and Hand Pad Morphology of Southern Lesser Bush Babies (Galago moholi): A Comparison with G. senegalensis (2000)
    Springer
    International journal of primatology 21 (2000), S. 537-555 
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    ISSN: 1573-8604
    Keywords: galago ; taxonomy ; vocalization ; morphology ; zoogeography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous studies have shown the taxonomic value of vocal repertoires and hand (volar) pad characteristics in the classification of cryptic nocturnal primates such as bush babies. However, no study included quantitative comparisons within the geographical range of any one species. We investigated levels of intraspecific variation in calls and hand pad characteristics of the southern lesser bush baby (Galago moholi), using the northern lesser bush baby (Galago senegalensis) for interspecific comparisons. Examination of calls recorded from different regions along a transect of 1500 km across southern Africa revealed low levels of intraspecific variation in Galago moholi, whereas comparisons with homologous call-types in G. senegalensis revealed them to be significantly different. Volar pad measurements across the ranges of both species also showed low levels of intraspecific variation and relatively high interspecific variation. These findings demonstrate that vocal and volar pad characteristics can be used as consistent measures of difference between species that look almost identical. These methods provide a practical means of distinguishing between cryptic species, whether in the field, in captivity, or, in the case of volar pads, of preserved specimens.
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    Taxonomic Revision of Mouse Lemurs (Microcebus) in the Western Portions of Madagascar (2000)
    Springer
    International journal of primatology 21 (2000), S. 963-1019 
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    ISSN: 1573-8604
    Keywords: mouse lemurs ; Microcebus ; taxonomy ; revision ; new species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genus Microcebus (mouse lemurs) are the smallest extant primates. Until recently, they were considered to comprise two different species: Microcebus murinus, confined largely to dry forests on the western portion of Madagascar, and M. rufus, occurring in humid forest formations of eastern Madagascar. Specimens and recent field observations document rufous individuals in the west. However, the current taxonomy is entangled due to a lack of comparative material to quantify intrapopulation and intraspecific morphological variation. On the basis of recently collected specimens of Microcebus from 12 localities in portions of western Madagascar, from Ankarana in the north to Beza Mahafaly in the south, we present a revision using external, cranial, and dental characters. We recognize seven species of Microcebus from western Madagascar. We name and describe 3 spp., resurrect a previously synonymized species, and amend diagnoses for Microcebus murinus (J. F. Miller, 1777), M. myoxinus Peters, 1852, and M. ravelobensis Zimmermann et al., 1998.
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    Phylogenetic Relationships of Spider Monkeys (Ateles) Based on Mitochondrial DNA Variation (2000)
    Springer
    International journal of primatology 21 (2000), S. 381-420 
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    ISSN: 1573-8604
    Keywords: phylogenetics ; taxonomy ; systematic ; Ateles ; Cebidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Our goal was to determine phylogenetic relationships among geographically and taxonomically distinct haplotypes of spider monkeys (Ateles) based on DNA sequence variation for the mitochondrial DNA control region and cytochrome c oxidase subunit II gene. We obtained samples from most previously recognized subspecies of Ateles, ranging from Central America throughout the Amazon Basin, to determine phylogenetic relationships among racially recognized groups. Comparison of DNA sequences using both parsimony analysis and genetic distance analysis produced phylogenetic relationships that were very similar for each genetic region. We analyzed the phylograms produced, along with associated bootstrap support, confidence probabilities, and genetic distances between taxonomic groups, to identify four monophyletic species of Ateles: Ateles paniscus, composed of haplotypes from the northeastern Amazon Basin; A. belzebuth in the southern Amazon Basin; A. hybridus, located primarily along the Magdalena River valley of Colombia; and A. geoffroyi, which includes two former species: A. geoffroyi and A. fusciceps. This arrangement is contradictory to long-held taxonomies of Ateles based on pelage variation and is similar to a recent analysis based on craniodental variation. Results of this investigation suggest patterns of gene flow, evolutionary relationships, and speciation patterns that are more plausible than previous pelage-based taxonomies, which required seemingly impossible patterns of gene flow. Conservation efforts aimed at protecting Ateles, one of the Neotropics most endangered genera, will also benefit from the findings presented in this paper.
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    Use of Vocal Fingerprinting for Specific Discrimination of Gray (Microcebus murinus) and Rufous Mouse Lemurs (Microcebus rufus) (2000)
    Springer
    International journal of primatology 21 (2000), S. 837-852 
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    ISSN: 1573-8604
    Keywords: vocalization ; sexual advertisement ; predator advertisement ; taxonomy ; evolution ; mouse lemur ; primate ; Madagascar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Advertisement calls are often important noninvasive tools for discriminating cryptic species and for assessing specific diversity and speciation patterns in nature. We investigated the contribution of these calls to uncover specific diversity in nocturnal Malagasy lemurs. We compared sexual advertisement and predator advertisement calls of two mouse lemur species, western gray and eastern rufous mouse lemurs (Microcebus murinus and M. rufus, respectively) living in two contrasting habitats (dry deciduous vs. rain forest), and analyzed them statistically. Both species emitted several highly variable whistle calls in the context of predator-avoidance. Intrapopulation variation was high and overlapped interspecific variation. Sexual advertisement calls, given in the mating context, displayed a totally distinct, species-specific acoustic structure. Whereas gray mouse lemurs produced rapidly multifrequency modulated, long trill calls, rufous mouse lemurs gave slowly frequency-modulated short chirp calls. Our results suggest specific status for gray and rufous mouse lemurs and indicate the importance of predation and social needs in shaping vocal communication.
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    Neue Beobachtungen zur Morphologie des Zapfens vonPinus und ihre Bedeutung für die Systematik, Fossil-bestimmung, Arealgestaltung und Evolution der Gattung (1980)
    Springer
    Plant systematics and evolution 134 (1980), S. 137-171 
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    ISSN: 1615-6110
    Keywords: Pinaceae ; Pinus ; Palaeobotany ; cone morphology ; apophysis characters ; shape and position of umbo and mucro ; taxonomy ; evolution ; distribution pattern and fossils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new approach to the classification ofPinus based on analyses of umbo and mucro on the cone scales is presented. It matches the basic frame of existing classification systems and allows determination of sections or even species. In particular, the subdivision ofDiploxylon pines into groups with centric or excentric mucro separates most Eurasian from American species. Fossils with well preserved mucro now can be grouped better and determined with more accuracy. Furthermore, umbo analyses which consider the ontogeny of the conelets and the shift from primitive to derived character states from the apex to the basis of mature cones lead to an additional evaluation of relationships and evolutionary lines among pines.
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    Cell structure and reproduction process in the Blue-Green algaChamaesiphon (1982)
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    Plant systematics and evolution 139 (1982), S. 267-277 
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    ISSN: 1615-6110
    Keywords: Cyanophyceae ; Chamaesiphonales ; Chamaesiphon ; Ultrathin sections ; cell wall ; cell structures ; cell division ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ultrathin sections were studied in 2 strains and 2 samples from the nature of the genusChamaesiphon, representing 4 different species. Thylakoids are distributed mainly on the periphery of the cells, the cell-wall is probably 2-layered, and variable multilayered mucilaginous envelopes are developed around the cells. The cell division starts, as well as in otherCyanophyceae, by the invagination of the cytoplasmic membrane and of cell-wall layers into the protoplast; the mucilaginous envelopes—pseudovaginae—do not participate in this process but they form only the firm sheaths around the cells. The way of reproduction is, therefore, essentially the same as that described in other chroococcal Blue-Green algae (e.g.,Synechococcus), and the main difference is the polarized growth of theChamaesiphon cells. The taxonomical position of chamaesiphonoid algae is not as isolated as it was earlier supposed, the similarity withEntophysalidaceae is evident.
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    Mikromorphologie und Orientierungsmuster epicuticularer Wachs-Kristalloide: Ein neues systematisches Merkmal bei Monokotylen (1983)
    Springer
    Plant systematics and evolution 142 (1983), S. 171-185 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Monocotyledonae ; Epicuticular wax ; micromorphology ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on SEM examinations of some 1600 species of monocotyledons out of 61 families the characteristics of their epicuticular waxes are described in this preliminary paper and illustrated by 20 SEM micrographs. Four basic types of waxes are recognized. Two of them occur throughout the monocotyledonous and dicotyledonous orders of angiosperms; two others are of high systematic significance and restricted to particular orders of the monocotyledons: The “Convallaria-Type” is characterized by fine wax platelets with parallel orientation, forming a pattern around the stomata reminiscent of electromagnetic field lines. This type is restricted to the three liliiflorous ordersAsparagales, Liliales, andBurmanniales. The “Strelitzia-Type” is characterized by massive compound wax rodlets; it is restricted to the superordersAreciflorae, Commeliniflorae, Zingiberiflorae, plus the two liliiflorous ordersBromeliales andVelloziales. The data are compared with the classifications ofDahlgren & Clifford (1982); they tentatively indicate the exclusion ofBromeliales, Velloziales, andTyphales from theLiliiflorae.
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    Epicuticular wax morphology and the taxonomy ofRosa (sectionCaninae, subsectionRubiginosae) (2000)
    Springer
    Plant systematics and evolution 221 (2000), S. 107-112 
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    ISSN: 1615-6110
    Keywords: Rosaceae ; Rosa ; Caninae ; epicuticular waxes ; taxonomy ; hybridism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Classification within the genusRosa is problematic due to ± continuous variation of morphological characters. The dogroses, (Rosa, sectionCaninae) are classified only by their unique meiotic system not by directly visible characters. The intrasectional structure remains insufficient, as the characters (glands, hairs and prickles) are known to exhibit great morphological divergence affected by both genetic plasticity and environmental influences. Taxonomy of dogroses follows a highly artificial system which allows us to identify morphospecies, which are not necessarily evolutionary species. However, SEM-studies in theCaninae revealed that all taxa of the subsectionRubiginosae are characterised by a granule type of epicuticular waxes, whereas members from the other subsections (with three exceptions) form triangular rodlets. Comparison with specimens grown under the same conditions confirmed these findings on natural populations and additionally revealed that following artificial hybridism, offspring develop the maternal type of wax structure due to the matroclinal inheritance in this section.
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    Morphological and cytological investigations ofUlothrix zonata and taxonomy of the related species (1980)
    Springer
    Plant systematics and evolution 135 (1980), S. 151-158 
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    ISSN: 1615-6110
    Keywords: Ulothrix ; Ulotrichales ; Ohlorophyceae ; Morphology ; reproduction ; cytology ; polymorphism ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present communication deals with the observations made on the morphology, reproduction and cytology ofUlothrix zonata (Weber & Mohr)Kütz. in culture. The alga displays a remarkable phenotypic plasticity in nature as well as in culture. The present study provides additional evidence of karyology in support ofLokhorst andVroman's treatment ofU. zonata which merges a number of earlier described species in it. The cytological details and chromosome number (n = 10) determined for the Indian isolates ofU. zonata agree with those ofSarma for the British material.
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    Software dependent phenetic relationships of non-nodulating African species ofAcacia (2000)
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    Plant systematics and evolution 220 (2000), S. 139-146 
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    ISSN: 1615-6110
    Keywords: Acacia ; classification ; Leguminosae ; morphology ; phenetics ; RAPD ; software ; taxonomy ; UPGMA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phenetic analysis of non-nodulatingAcacia species by Harrier et al. (1997) was repeated to illustrate how different computer programs may generate alternative UPGMA trees for the very same data, even in the absence of data input order effects (ties). For example, all Harrier et al.'s UPGMA dendrograms produced by software from the Scottish Agricultural Statistics Service differed from those obtained by the packages NTSYS and MVSP87. Particularly, the positions ofA. albida, A. rovumae, andA. pentagona, as well as the relationships betweenDiacanthae andTriacanthae were affected by this phenomenon. Hence, whenever clustering techniques are used, care should be taken to consider possible software-dependent caveats and artefacts. Nevertheless, all programs provided clusterings that largely coincided with the subgeneric and sectional groupings proposed by Vassal (1972) although the positions of some species varied depending on whether morphological or molecular data were considered (e.g.A. albida andA. rovumae).
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    Secretory cavities and pellucid dots in leaflets ofLonchocarpus (Leguminosae, Papilionoideae, Millettieae) (2000)
    Springer
    Plant systematics and evolution 221 (2000), S. 61-68 
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    ISSN: 1615-6110
    Keywords: Leguminosae ; Papilionoideae ; Lonchocarpus ; leaflets ; secretory cavities ; false secretory cavities ; pellucid dots ; glands ; anatomy ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The occurrence of leaflet secretory cavities in 23 Brazilian species ofLonchocarpus was surveyed anatomically and compared with data from external morphology (presence of pellucid dots) to evaluate their taxonomic significance. This study revealed three cases: presence of secretory cavities associated with pellucid dots, pellucid dots corresponding to false secretory cavities, and absence of pellucid dots and secretory cavities. These results indicate that in this genus the “glandular pellucid dots” cited in morphological descriptions do not always correspond to secretory cavities, and that their nature must always be confirmed by histological sections. Secretory cavities have systematic significance at subgeneric taxonomic level for the genusLonchocarpus.
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    New chromosome counts inStreptocarpus (Gesneriaceae) from Madagascar and the Comoro Islands and their taxonomic significance (2000)
    Springer
    Plant systematics and evolution 224 (2000), S. 173-182 
    Details
    ISSN: 1615-6110
    Keywords: Gesneriaceae ; Streptocarpus ; Chromosome numbers ; growth patterns ; taxonomy ; Africa ; Comoro Islands ; Madagascar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study records the chromosome numbers of 10 species ofStreptocarpus; nine of the counts are new. With the exception ofS. buchananii of mainland Africa, all the results are for plants endemic to Madagascar and the Comoro Islands. While there is a strong correlation between basic number and growth form in the two subgenera of the genus on the African mainland (x = 15 among caulescent species in subgenusStreptocarpella; x = 16 among acaulescent species in subgenusStreptocarpus), the situation appears more complex among Madagascan and Comoro Island species. One notable example of deviation from this correlation is shown byS. papangae, a shrubby caulescent species, with 2n = 32 (x = 16). Polyploidy in the genus appears to be absent on mainland Africa, but is present in Madagascar and the Comoro Islands, ranging from tetraploidy to octoploidy. Evolutionary implications of the cytological observations are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00986341
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    Inter- and intraspecific genetic variation inHippophae (Elaeagnaceae) investigated by RAPD markers (2000)
    Springer
    Plant systematics and evolution 225 (2000), S. 85-101 
    Details
    ISSN: 1615-6110
    Keywords: Elaeagnaceae ; Hippophae ; sea buckthorn ; Systematics ; taxonomy ; genetic variation ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic diversity has been investigated by the application of molecular markers in, for the first time, all the taxa recognised in recent treatises of the genusHippophae. RAPD (random amplified polymorphic DNA) analyses were conducted with 9 decamer primers, which together yielded 219 polymorphic markers. We found 16 fixed RAPD markers, i.e. markers that either occurred in all plants of a population or were absent from all plants. Several of these markers were useful for analysis of interspecific relationships, whereas others can be considered as taxon-specific markers. Clustering of taxa and populations in our neighbour-joining based dendrogram was in good agreement with some recently suggested taxonomic treatises ofHippophae. Amount and distribution of genetic variability varied considerably between species. Partitioning of molecular variance withinH. rhamnoides supported earlier findings that a considerable part of the total variance resides among subspecies (59.6%) Within-population variability also differed considerably. Percentage polymorphic RAPD loci and Lynch and Milligan within-population gene diversity estimates showed relatively high values for some species close to the geographic centre of origin in Central Asia, e.g.H. tibetana and the putatively hybridogenousH. goniocarpa. Spatial autocorrelation analyses performed on 12 populations ofH. rhamnoides revealed positive autocorrelation of allele frequencies when geographic distances ranged from 0 to 700 km, and no or negative autocorrelation at higher distances. At distances between 700 and 1900 km, we observed deviations from the expected values with strongly negative autocorrelation of allele frequencies. A corresponding relationship between geographic and genetic distances could not be found when the analysis instead was based on one population from each of 8 species.
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    URL: http://dx.doi.org/10.1007/BF00985460
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    Effect of long-term fertilizer treatments on groundnut yield, nodulation, and nutrient uptake at Samaru, Nigeria (1980)
    Springer
    Plant and soil 55 (1980), S. 171-180 
    Details
    ISSN: 1573-5036
    Keywords: Groundnut fertilization ; Nigeria ; Nitrogen fixation ; Nodulation ; Nutrient uptake ; Tropical soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It was observed in a long-term fertility study that P application results in better nodulation and seed yield. The N yield per plant increased significantly with P, K, and B application, but the promoting effect of K and B on N content per plant was not reflected in the final yield. Data on mean nutrient uptake indicate that about 63% of N, 68% of P, 23% of K, 4% of Ca and 24% of Mg were present in the kernels, the remainder being in the haulm and shells. Soil will be exhausted fast if the nutrient rich groundnut residues are completely exported from the field and not compensated by adequate fertilizer application. Judicious use of fertilizers on groundnut has been shown to yield more than 100 kg of biologically fixed N per hectare.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181796
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    The effect of source, concentration and time of application of nitrogen on the growth, nodulation and nitrogen fixation ofLotus pedunculatus andTrifolium repens (1983)
    Springer
    Plant and soil 74 (1983), S. 83-91 
    Details
    ISSN: 1573-5036
    Keywords: Clover ; Fertilizer ; Lotus ; Nitrogen fertilizer ; Nitrogen fixation ; Nitrogen source ; Nodulation ; Trifolium repens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Studies under growth cabinet conditions investigated the effect of source and concentration of nitrogen and timing of nitrogen application on the growth and nitrogen fixation byLotus pedunculatus cv. Maku andTrifolium repens cv. S184. KNO3, NaNO3 and NH4NO3 were added at transplanting at the following rates: 3.33, 7.78 and 13.33 mg N/plant. KNO3 was added at 3.33 and 7.78 mg N/plant at 0, 6, 12, 18, 24 or 30 days after transplanting. Lotus shoot weight increased with all increasing nitrogen sources but clover only responded to KNO3 and NaNO3. The root weight of both species increased with increasing KNO3 and NH4NO3. The percentage increase in lotus and clover shoot growth was greater than that of root growth when KNO3 was added within a week of transplanting. Increases in growth by both species resulted from added nitrogen except with lotus when NaNO3 was applied where increased nitrogen fixation also contributed to increased growth. Weight and number of effective nodules on both species were increased with 3.33 mg N per plant as KNO3 but nitrogen fixation was not affected. Addition of 13.33 mg N as NaNO3 reduced weight and number of effective nodules in both species and also nitrogen fixation by lotus. KNO3 increased growth and nodulation of both species when applied within one week after transplanting. Nodulated lotus plants responded to KNO3 by increasing growth but not nodulation. KNO3 appeared to affect infection and development of nodules on lotus and may affect the growth of existing nodules on clover.
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    URL: http://dx.doi.org/10.1007/BF02178743
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    Effect of soil moisture stress on yield, nodulation and nitrogenase activity ofMacroptilium atropurpureum cv. Siratro andDesmodium intortum cv. Greenleaf (1980)
    Springer
    Plant and soil 57 (1980), S. 187-194 
    Details
    ISSN: 1573-5036
    Keywords: Moisture stress ; Nitrogen fixation ; Tropical forage legume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of soil moisture stress on growth, nodulation and nitrogenase activity of two tropical forage legumes,Macroptilium atropurpureum cv. Siratro andDesmodium intortum cv. Greenleaf was studied in a pot experiment. After ten weeks growth, the highest moisture stress (20 per cent water holding capacity) significantly reduced only the top weight of both plants. Moisture stress progressively retarded top growth in the two legumes. Similar trends were also observed in defoliated plants. Moisture stress had little or no effect on the nodulation or nitrogenase activity of the plants.
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    URL: http://dx.doi.org/10.1007/BF02211678
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    Nodulation and N2-fixation byInga jinicuil, a woody legume in coffee plantations (1981)
    Springer
    Plant and soil 59 (1981), S. 201-206 
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    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Coffee plantation ; Inga jinicuil ; Nitrogen fixation ; Nodule biomass ; Woody legume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nodule biomass and yearly C2H2 reduction rates are reported forInga jinicuil, a leguminous tree used for shade in Mexican coffee plantations. Annual fixation by this species approximates 35 kg ha−1; which, when compared to nitrogen additions from fertilizers, represents an important nitrogen input to the coffee ecosystem.
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    URL: http://dx.doi.org/10.1007/BF02184193
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    Gnotobiotic cultures of rice plants up to ear stage in the absence of combined nitrogen source but in the presence of free living nitrogen fixing bacteriaAzotobacter vinelandii andRhodopseudomonas capsulata (1981)
    Springer
    Plant and soil 60 (1981), S. 85-97 
    Details
    ISSN: 1573-5036
    Keywords: Azotobacter vinelandii ; Gnotobiotic cultures ; Nitrogen fixation ; Oryza sativa Rhodopseudomonas capsulata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An all glass tight growth chamber, entirely sterilizable, has been constructed to carry out axenic and gnotobiotic cultures of rice plants (Oryza sativa L.). When grown in liquid medium and in the absence of combined nitrogen but in the presence of the diazotrophsAzotobacter vinelandii andRhodopseudomonas capsulata, rice plants exhibited a complete biological cycle from germination up to ear stage, during a period of time similar to the one encountered in french paddy soil of Camargue. In one experiment, mannitol was given to rice culture medium together withAzotobacter vinelandii andRhodopseudomonas capsulata. In another experiment, mannitol was not given together with Rhodopseudomonas, and still positive nitrogen gain was obtained, although it was less than culture with mannitol. When15N labeled cells of Rhodopseudomonas were added in rice culture medium,15N was partly transferred to rice plant. Among the nitrogen substances excreted from the bacteria in the rhizosphere medium, large organic molecules were shown to be the most abundant in our experimental conditions. Moreover, the concentration of free ammonia or aminoacids present in the rice rhizosphere were always compatible with a bacterial nitrogenase activity.
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    URL: http://dx.doi.org/10.1007/BF02377114
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    A comparison of nitrogen-fixing ability of peanut, cowpea and siratro plants nodulated by different strains of Rhizobium (1981)
    Springer
    Plant and soil 60 (1981), S. 317-319 
    Details
    ISSN: 1573-5036
    Keywords: Bacteroids ; Cowpea ; Nitrogen fixation ; Peanut ; Rhizobium ; Siratro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Acetylene reduction activity and nitrogen accumulation in the plant top per unit nodule mass were compared among peanut, cowpea and siratro plants nodulated by six different strains of Rhizobium. Peanut was found to have several fold higher values than cowpea and siratro for both parameters for all strains of Rhizobium which nodulated it effectively, but the bacteroid content of the peanut nodules was similar to those of cowpea and siratro.
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    URL: http://dx.doi.org/10.1007/BF02374116
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    A further extension of the method for independently measuring the amount of nitrogen fixed by a legume crop (1981)
    Springer
    Plant and soil 62 (1981), S. 331-336 
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    ISSN: 1573-5036
    Keywords: Legumes ; Nitrogen fixation ; 15N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The combination of using15N for determining the amount of nitrogen fixed by a legume crop in field experiments and the labelling of only one treatment at a time in each treatment combination is shown to be conceptually and experimentally valid for determining the effect of cultural practices on the amount of nitrogen fixed by a legume crop.
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    URL: http://dx.doi.org/10.1007/BF02374100
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    Ectomycorrhizae in coastal miombo woodland of Tanzania (1981)
    Springer
    Plant and soil 63 (1981), S. 283-289 
    Details
    ISSN: 1573-5036
    Keywords: Afzelia quanzensis ; Brachystegia spiciformis ; Ectomycorrhiza ; Miombo woodland ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ectomycorrhizae were found in root samples of the treesAfzelia quanzensis Welw. andBrachystegia spiciformis Benth. (Caesalpiniaceae), collected in the coastal miombo type woodland 50 km west of Dar-es-Salaam, Tanzania. Root nodules with a structure resembling that of nitrogen-fixing root nodules of other leguminous plants were observed in theA. quanzensis material. The climate of the locality is rather dry, and strongly seasonal. In the tropics, ectomycorrhizae have previously been found only in humid or rain forest climate zones.
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    URL: http://dx.doi.org/10.1007/BF02374606
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    Position of mesquite (Prosopis spp) nodulation and nitrogen fixation (acetylene reduction) in 3-m long phraetophytically simulated soil columns (1982)
    Springer
    Plant and soil 64 (1982), S. 297-305 
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    ISSN: 1573-5036
    Keywords: Drought stress ; Nitrogen fixation ; Nodulation ; Prosopis spp ; Semi-arid ; Tree legumes ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The literature does not contain a field report of nodulation for the xerophytic tree legumes of the genus Prosopis despite their widespread occurrence in semi-arid regions of the world. A phraetophytically simulated greenhouse experiment was conducted with mesquite in a 3m deep soil column to determine if nodules would form in deper depths where moisture is more abundant. The upper 0.5m in the soil column was allowed to dry to 2200 kPa but the 3.2 m depth was maintained at soil moistures more positive than 70 kPa by water additions to the bottom of the soil column. Over 100 nodules and an acetylene reduction rate of 1.9 mg/h were observed at the 3.2m depth. Nodulation or acetylene reduction were not observed closer than 2.7m from the surface. Air temperatures during these assays exceeded 45°C. Leaf xylem water potentials were in the 2800–3500 kPa range.
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    URL: http://dx.doi.org/10.1007/BF02372512
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    Nodulation and nitrogen fixation in Purshia: inoculation responses and species comparisons (1982)
    Springer
    Plant and soil 65 (1982), S. 383-396 
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    ISSN: 1573-5036
    Keywords: Frankia ; Microbial ecology ; Nitrogen fixation ; Purshia ; Revegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrogen fixing trees and shrubs may be useful in revegetation efforts. Speculation that insufficient endophyte populations in surface soils may limit non-leguminous symbiotic nitrogen fixation in marginal land was explored.Purshia tridentata andP. glandulosa seedlings were grown in greenhouse trials using ten soils from nativePurshia sites. Treatments include a control, an inoculated treatment, and six mmole nitrogen amendment. When inoculated with aP.tridentata crushed nodule inoculum, two of five non-nodulating soils and three sparsely nodulating soils produced well nodulated plants. Inoculation also increased nodule mass, total nitrogen, nitrogen content and shoot dry mass in plants from some of the soils. Of the three soils failing to produce nodulated plants when inoculated, one produced plants that responded well to nitrogen additions but failed to nodulate under low nitrogen conditions; another produced severely stunted plants indicating nutritional limitations on the host; and the third produced plants that were not nitrogen deficient. An application of nitrogen completely suppressed nodulation in all but one soil. The twoPurshia species were similar in nodulation, nitrogen fixation and growth, although important exceptions exist that indicate species may differ in adaptability to certain soil conditions.
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    URL: http://dx.doi.org/10.1007/BF02375059
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    Natural senescence of the root cortex of spring wheat in relation to susceptibility to common root rot (Cochliobolus sativus) and growth of a free-living nitrogen-fixing bacterium (1982)
    Springer
    Plant and soil 66 (1982), S. 13-20 
    Details
    ISSN: 1573-5036
    Keywords: Acridine orange ; Cochliobolus sativus ; Common root rot ; Nitrogen fixation ; Nuclear staining ; Roots ; Senescence ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Natural senescence of the root cortex was assessed by nuclear staining, for cultivars and chromosome substitution lines of spring wheat known to differ in (1) susceptibility to common root rot, (2) total rhizosphere populations and (3) ability to support growth of a free-living nitrogen-fixing bacterium. Together, three root rot susceptible wheat lines showed significantly more cortical senescence than did three resistant lines; the susceptible lines also support larger rhizosphere populations. The wheat line that supports growth of a nitrogen-fixing bacterium showed significantly less cortical death than did any other line. Substitution of chromosome pairs 5B or 5D between the parent cultivars Rescue and Cadet substantially altered the amount of root cortex death, which is thus genetically determined. It is suggested thatCochliobolus sativus and other weak parasites benefit from early natural senescence of the root cortex, and that the degree of susceptibility or resistance of wheat lines to common root rot is at least partly determined by differences in cortical senescence.
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    URL: http://dx.doi.org/10.1007/BF02203397
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    Utility of phyllosphere N2-fixing micro-organisms in the improvement of crop growth (1982)
    Springer
    Plant and soil 68 (1982), S. 55-67 
    Details
    ISSN: 1573-5036
    Keywords: Klebsiella ; Nitrogen fixation ; Oryza sativa ; Phyllosphere ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The beneficial effect of spraying some highly active phyllosphere N2-fixing microorganisms on high and low yielding cultivars of rice plants as compared with that of urea applied at different doses are described. The dry weight, N-content, 1000 grain weight, and yield were remarkably increased in all cases with the application of phyllosphere microorganisms. The performance of two isolates KUP4 and KUPBR2 with IR-8 and IR-26 rice, was better than that of 52 kg urea-N per hectare. IR-579 rice leaves in association with some phyllosphere bacteria reduced acetylene at the rate of 664–816 nmoles/g leaf/h. In IR-26 rice the effect of application of bacterial suspension at three phases of plant growth corresponded very well with that of urea application in three split doses under identical conditions. Recommended fertilizer rates produced the same yield as the half dose plus bacterial spray in the cultivars Pankaj and Rupsail. Fertilizer application in Pankaj and Rupsail rice reduced nitrogenase activity and the beneficial effects of phyllosphere N2-fixation was reduced by 40–55%.
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    URL: http://dx.doi.org/10.1007/BF02374727
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    Nitrogen fixation byAzospirillum spp. and effect ofAzospirillum lipoferum on the yield and N-uptake of wheat crop (1982)
    Springer
    Plant and soil 69 (1982), S. 233-238 
    Details
    ISSN: 1573-5036
    Keywords: Nitrogen fixation ; Azospirillum spp. ; Azospirillum lipoferum ; Wheat yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seven isolates belonged toA. brasilense and 3 belonged toA. lipoferum. Isolates having more denitrifying capacity fixed less nitrogen in nitrogen free semi-solid malate medium. One strain ofA. lipoferum having high nitrogen fixing capacity with negative test for denitrification was tested as inoculant to supplement the nitrogen need of a wheat crop in field condition with different doses of N with and without the inoculant. While control without nitrogen yielded 1260 kg/ha the yield in inoculated treatment was 2070 kg/ha resulting in significant increase. In a treatment receiving 40 kg N/ha the grain yield was 2370 kg/ha as against yield of 3110 kg/ha in a similar treatment receiving fertiliser plus inoculant. Thus increase in yield was about 30%. Further the treatment receiving 80 kg N/ha yielded 2970 kg/ha as against yield of 4150 kg/ha in a treatment receiving inoculant alongwith the above dose of the fertiliser. Thus increase in yield due to application of inoculant was about 36%. Similarly, the uptake of N in different treatments was augmented due to inoculation of seeds with the culture.
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    URL: http://dx.doi.org/10.1007/BF02374518
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    Frankia growth and activity as influenced by water potential (1982)
    Springer
    Plant and soil 69 (1982), S. 293-297 
    Details
    ISSN: 1573-5036
    Keywords: Ecology ; Frankia ; Nitrogen fixation ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth responses of Frankia isolates to decreasing water potential were monitored in systems where potentials were controlled by KCl, NaCl and Polyethylene glycol. The highest potential tested was −2 bar (basal medium). The general pattern emerging was that isolates fromAlnus glutinosa, A. viridis andComptonia peregrina showed declining growth at potentials below −2 to −5 bar. AMyrica gale isolate showed declining growth with decreasing potential. All isolates were more sensitive to decreases in potential in a matric controlled than an osmotic controlled system. They all showed approximately 50 percent growth reduction at −5 to −8 bar, and meagre growth at −16 bar after 35 days. The Comptonia isolate was the most vigorous at low potentials. Nitrogen fixation ability was monitored for two isolates. Highest specific activities were observed between −3 and −5 bar for the Myrica isolate and between −5 and −7.5 bar for theA. glutinosa isolate.
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    Nitrogen fixation in the rhizosphere and rhizoplane of barley (1982)
    Springer
    Plant and soil 69 (1982), S. 341-352 
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    ISSN: 1573-5036
    Keywords: Barley ; Nitrogen fixation ; Rhizoplane ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Aerobic and anaerobic N2-fixing bacteria developed in the rhizosphere of barley seedlings and exhibited N2ase activity when seedlings were grown in sterilized sand-nutrient cultures containing low levels of combined nitrogen. The source of the N2-fixing bacteria appeared to be the seed. Average daily rates up to 0.9 μmoles C2H4 h−1 g−1 dry root tissue were measured, but the intensity of the activity was affected by moisture levels and concentration of combined N in the rhizosphere. Removal and washing of the roots did not remove the activity, and roots remained active even after surface-sterilization. An unidentified aerobic N2-fixing bacterium was isolated from the rhizoplane of active barley roots. Inoculation of barley seedlings with the aerobic N2-fixing bacterium enhanced N2ase activity of excised roots 10-fold, with average rates of 0.9, 1.1 and 1.3 μmoles h−1 g−1 dry root assayed under pO2 of 0.01, 0.02 and 0.04 atm respectively. The aerobic N2-fixing bacterium also exhibited N2ase activity when inoculated into the rhizosphere of oat, rice and wheat seedlings. Microscopic observations of sterilized live and stained barley roots suggest that the aerobic N2-fixing bacterium is an endophyte which infects root tissue and metamorphoses into vesicle-like structures.
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    Genetic specificity of nitrogen nutrition in leguminous plants (1983)
    Springer
    Plant and soil 72 (1983), S. 321-334 
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    ISSN: 1573-5036
    Keywords: Leguminous plants ; Nitrogen fixation ; Protein ; Seed ; Yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Mineral nitrogen did not increase grain yield and seed protein levels ofVicia faba L. andLupinus luteus L. in field trials and pot experiments. Fixed N2 was substituted by mineral nitrogen in these cases because of inhibition of N2 fixation by mineral nitrogen. Contrary to these results mineral nitrogen increased grain yields and seed protein amounts ofLupinus albus L.,Pisum sativum L., andGlycine max. (L.) Merr. The nitrogen effect was caused at an early stage by saving energy due to inhibition of N2 fixation (measurement of gas exchange by means of IRGA). In case of the N application after flowering grain, yields and seed protein levels increased because the mineral N was an additional nitrogen source for plants. At this stage the plants had ceased fixing atmospheric nitrogen. The high sink activity of growing fruits induced a lack of assimilates in nodules (determined by means of14CO2 application). The N effect was therefore the consequence of the lower assimilate pool for supplying root nodules in these plants in comparison withVicia faba L. andLupinus luteus L. Hence it follows that response to mineral nitrogen can be a criterion for discovering more effective Rhizobium-host combinations.
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    URL: http://dx.doi.org/10.1007/BF02181971
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    Diffusion du15N2 dans le sol pendant la mesure de fixation biologique de l'azote (1983)
    Springer
    Plant and soil 73 (1983), S. 431-434 
    Details
    ISSN: 1573-5036
    Keywords: Nitrogen fixation ; 15N2 diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary The kinetic of15N2 diffusion has been measured in a system similar to that for the estimation of N2 fixation in plant microorganism associations cultivated in soil. The15N2 enrichment of the soil atmosphere reached an homogenous value one hour after injection of15N2 and is identical to that obtained by calculation, indicating that no adsorption occurs in the soil particles.
    Notes: Résumé La cinétique de diffusion du15N2 est mesurée sur un système identique à ceux pouvant être utilisés pour la mesure de fixation de l'azote chez les associations plantes-microorganismes cultivées sur sol. L'enrichissement homogène de l'atmosphère du sol est obtenu une heure environ après l'injection de15N2 et correspond à l'enrichissement calculé, ce qui indique qu'aucune adsorption n'a lieu dans les particules du sol.
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    URL: http://dx.doi.org/10.1007/BF02184321
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    The relative efficiency of nitrogen fixation in pea root nodules (1983)
    Springer
    Plant and soil 75 (1983), S. 131-138 
    Details
    ISSN: 1573-5036
    Keywords: Hydrogen inhibition ; Nitrogen fixation ; Peas ; Relative efficiency ; Rhizobium leguminosarum ; Root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Experiments were performed to investigate the causes of low relative efficiency, RE, in legume root nodules. Nitrogen fixing activity and RE varied with time of incubation of nodules and with different temperatures and oxygen concentrations. The effects of nitrogen concentration and carbon dioxide concentration were also examined. In each case the RE was inversely related to nitrogen fixing activity; measured by acetylene reduction. Increasing the nitrogen concentration had no effect on either nitrogen fixing activity or RE. Experiments with isolated bacteroids gave higher RE values than the whole nodules from which they were isolated. All the results were consistent with hydrogen inhibition of nitrogenase within the nodule being the cause of low RE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02178620
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  • 97
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    Electronic Resource
    Morphology, physiology and infectivity of twoFrankia isolates An 1 and An 2 from root nodules ofAlnus nitida (1984)
    Springer
    Plant and soil 78 (1984), S. 45-59 
    Details
    ISSN: 1573-5036
    Keywords: Actinorhizae ; Alnus nitrida ; Frankia ; Host-specificity ; Nitrogen fixation ; Root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different strains, An 1 and An 2, were obtained from root nodules ofAlnus nitida Endl., collected from one locality in the area of its natural habitat near Bahrin, District Swat, Pakistan. The light and electron microscopy of the isolates revealed the occurrence of septate and branched hyphae bearing sporangia and vesicles. The strains differed in their growth requirements, nitrogen-fixing ability and production of extracellular pigments, thus indicating the existence of more than oneFrankia strain in the same locality. In the absence of combined nitrogen in the medium strain An 1 formed vesicles and fixed N2 (up to 200 nmol C2H4. mg protein−1.h−1), while strain An 2 under the experimental conditions formed only few vesicles and fixed N2 at a very low rate (ca 10 nmol C2H4. mg protein−1 .h−1). The nitrogenase activity of strain An 1 was strongly affected by the O2 concentration.Frankia An 1 and An 2 were infective and effective onA. nitida andA. glutinosa but not onDatisca cannabina andElaeagnus umbellata. Both An 1 and An 2 strains were more infective and effective onA. glutinosa thanFrankia strains AvcIl and CpI1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02277839
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  • 98
    Electronic Resource
    Electronic Resource
    Nitrogenase activity (acetylene reduction) associated with leaves of different cultivars of paddy (Oryza sativa L.) (1984)
    Springer
    Plant and soil 77 (1984), S. 253-261 
    Details
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Beijerinckia ; Nitrogen fixation ; Paddy ; Phyllosphere ; Silicification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An investigation was conducted to study the levels of nitrogen fixation on the leaf or sheath surfaces of four cultivars of paddy plants by using acetylene reduction technique. Varying levels of positive nitrogenase activity were observed on all the leaf surfaces. Sheath of IET 1991 cultivar showed a higher rate of fixation than the leaf surface. All the nitrogen-fixing organisms on the leaf or sheath surfaces belonged to the genus Beijerinckia. There was no correlation between the bacterial density and the level of fixation. Scanning electron microscopic data revealed that the upper surface of IET 1991 leaf was highly silicified and the microflora was either scanty or nil while the lower surface appeared quite different and harboured more micro-organisms. Similarly, the inner surface of sheath was devoid of silicification and showed the presence of micro-organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02182928
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  • 99
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    Electronic Resource
    Heterogeneity withinFrankia sp. LDAgpl studied among clones and reisolates (1984)
    Springer
    Plant and soil 78 (1984), S. 29-43 
    Details
    ISSN: 1573-5036
    Keywords: Alnus glutinosa ; Endophyte ; Frankia ; Infectivity ; Nitrogen fixation ; Sporulation ; Variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Frankia sp. LDAgpl, an isolate from spore positive nodules ofAlnus glutinosa, only slowly infects its host plant. Reisolates obtained from occasional nodules caused by infection with LDAgpl, are capable of infecting the alder much more rapidly. A variability analysis of LDAgpl has been performed to obtain more insight into the question whether these reisolates constitute a different genotype within LDAgpl and if the plant is exerting an influence during plant passage. High dilutions of mildly sonicatedFrankia suspensions were plated to obtain genetically homogeneous colonies. Clones thus generated showed differences in growth pattern, sporulation and C2H2-reduction on media containing propionic acid as sole C-source (P-medium). Differences in sporulation on P-medium indicate that LDAgpl was a highly heterogeneous strain. Comparisons of sporulation on several different media gave evidence that the differences in sporulation between LDAgpl clones are the result of differences in efficiency of propionic acid utilization. The differences observed between the reisolates and LDAgpl clones indicate that the reisolates constitute a different genotype, which could be selected for by the plant during the infection process. Comparison with similar changes in phenotype occuring in a spore negative type strain fromA. glutinosa is discussed.
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    URL: http://dx.doi.org/10.1007/BF02277838
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  • 100
    Electronic Resource
    Electronic Resource
    Physiological studies on N2-fixing root nodules ofDatisca cannabina L. andAlnus nitida Endl. from Himalaya region in Pakistan (1984)
    Springer
    Plant and soil 78 (1984), S. 129-146 
    Details
    ISSN: 1573-5036
    Keywords: Actinorhizas ; Alnus nitida ; Amino acid composition ; Datisca cannabina ; Hydrogen uptake ; Inoculation ; Nitrogen fixation ; Root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The nodulation and the morphology and physiology of the nodules were studied onDatisca cannabina, a perennial herb from northern Pakistan andAlnus nitida, a nodulated tree in the same locality. Both species bear coralloid clusters of actinorhizal nodules. The main free amino acid inD. cannabina nodules was arginine while the predominant free amino acid inA. nitida nodules was citrulline. The infectivity of crushed nodules of both types of plants on their respective host was about 106 infective particles per gram of nodule fresh wt. In cross-inoculation experiments crushed nodule inoculum fromA. nitida failed to induce nodulation onD. cannabina seedlings but the crushed nodule inoculum fromD. cannabina caused low nodulation on seedlings ofA. nitida (103 infective particles. g. nodule fresh wt.). The activity of nitrogenase, hydrogenase and respiration (O2 uptake) were measured in detached nodules, nodule homogenates and the 20 μm residue and 20 μm filtrate preparations from the nodules of both species. Both species showed similar patterns of activities except that only the nodule homogenate and 20 μm residue preparations fromD. cannabina showed pronounced enhancement of the O2 uptake by succinate which was further stimulated by ADP. This has in part been explained by the presence of mitochondria in close connection with the endophyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02277845
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