ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Nitrogen fixation
  • seaweed
  • Springer  (352)
  • Inter-Research  (1)
  • American Association for the Advancement of Science
  • American Institute of Physics (AIP)
  • 2010-2014  (3)
  • 1995-1999  (124)
  • 1980-1984  (226)
Collection
Keywords
Publisher
Years
Year
  • 1
    facet.materialart.
    Unknown
    Controls of benthic nitrogen fixation and primary production from nutrient enrichment of oligotrophic, Arctic lakes (2013)
    Springer
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ecosystems 16 (2013): 1550-1564, doi:10.1007/s10021-013-9701-0.
    Description: We examined controls of benthic dinitrogen (N2) fixation and primary production in oligotrophic lakes in Arctic Alaska, Toolik Field Station (Arctic Long-Term Ecological Research Site). Primary production in many oligotrophic lakes is limited by nitrogen (N), and benthic processes are important for whole-lake function. Oligotrophic lakes are increasingly susceptible to low-level, non-point source nutrient inputs, yet the effects on benthic processes are not well understood. This study examines the results from a whole-lake fertilization experiment in which N and P were added at a relatively low level (4 times natural loading) in Redfield ratio to a shallow (3 m) and a deep (20 m) oligotrophic lake. The two lakes showed similar responses to fertilization: benthic primary production and respiration (each 50–150 mg C m−2 day−1) remained the same, and benthic N2 fixation declined by a factor of three- to fourfold by the second year of treatment (from ~0.35 to 0.1 mg N m−2 day−1). This showed that the response of benthic N2 fixation was de-coupled from the nutrient limitation status of benthic primary producers and raised questions about the mechanisms, which were examined in separate laboratory experiments. Bioassay experiments in intact cores also showed no response of benthic primary production to added N and P, but contrasted with the whole-lake experiment in that N2 fixation did not respond to added N, either alone or in conjunction with P. This inconsistency was likely a result of nitrogenase activity of existing N2 fixers during the relative short duration (9 days) of the bioassay experiment. N2 fixation showed a positive saturating response when light was increased in the laboratory, but was not statistically related to ambient light level in the field, leading us to conclude that light limitation of the benthos from increasing water-column production was not important. Thus, increased N availability in the sediments through direct uptake likely caused a reduction in N2 fixation. These results show the capacity of the benthos in oligotrophic systems to buffer the whole-system response to nutrient addition by the apparent ability for significant nutrient uptake and the rapid decline in N2 fixation in response to added nutrients. Reduced benthic N2 fixation may be an early indicator of a eutrophication response of lakes which precedes the transition from benthic to water-column-dominated systems.
    Description: This project was supported by NSF-OPP 9732281, NSF-DEB 9810222, NSF-DEB 0423385, and by a Doctoral Dissertation Improvement Grant NSF-DEB 0206173. Additional funding was provided by the Small Grants Program through the NSF-IGERT Program in Biogeochemistry and Environmental Change at Cornell University.
    Keywords: Benthic ; Nitrogen fixation ; Primary production ; Oligotrophic ; Arctic ; Toolik
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: application/msword
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    Using indirect methods to constrain symbiotic nitrogen fixation rates : a case study from an Amazonian rain forest (2010)
    Springer
    Details
    Publication Date: 2022-05-25
    Description: © The Authors 2009. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License. The definitive version was published in Biogeochemistry 99 (2010): 1-13, doi:10.1007/s10533-009-9392-y.
    Description: Human activities have profoundly altered the global nitrogen (N) cycle. Increases in anthropogenic N have had multiple effects on the atmosphere, on terrestrial, freshwater and marine ecosystems, and even on human health. Unfortunately, methodological limitations challenge our ability to directly measure natural N inputs via biological N fixation (BNF)—the largest natural source of new N to ecosystems. This confounds efforts to quantify the extent of anthropogenic perturbation to the N cycle. To address this gap, we used a pair of indirect methods—analytical modeling and N balance—to generate independent estimates of BNF in a presumed hotspot of N fixation, a tropical rain forest site in central Rondônia in the Brazilian Amazon Basin. Our objectives were to attempt to constrain symbiotic N fixation rates in this site using indirect methods, and to assess strengths and weaknesses of this approach by looking for areas of convergence and disagreement between the estimates. This approach yielded two remarkably similar estimates of N fixation. However, when compared to a previously published bottom-up estimate, our analysis indicated much lower N inputs via symbiotic BNF in the Rondônia site than has been suggested for the tropics as a whole. This discrepancy may reflect errors associated with extrapolating bottom-up fluxes from plot-scale measures, those resulting from the indirect analyses, and/or the relatively low abundance of legumes at the Rondônia site. While indirect methods have some limitations, we suggest that until the technological challenges of directly measuring N fixation are overcome, integrated approaches that employ a combination of model-generated and empirically-derived data offer a promising way of constraining N inputs via BNF in natural ecosystems.
    Description: We acknowledge and are grateful for financial support from the Andrew W. Mellon Foundation (C.C. and B.H.), the National Science Foundation (NSF DEB-0515744 to C.C. and A.T. and DEB-0315656 to C.N.), and the NASA LBA Program (NCC5-285 to C.N.).
    Keywords: Amazon Basin ; Ecosystem modeling ; Mass balance ; Nitrogen fixation ; Nutrient cycling ; Rondonia ; Tropical forest
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 3
    facet.materialart.
    Unknown
    Ecological constraints on planktonic nitrogen fixation in saline estuaries. I. Nutrient and trophic controls (2011)
    Inter-Research
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © Inter-Research, 2006. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 309 (2006): 25-39, doi:10.3354/meps309025.
    Description: Heterocystous, planktonic cyanobacteria capable of fixing atmospheric N2 into available nitrogen (N) are common and critically important to nutrient cycling in many lakes, yet they are rarely observed in estuaries at salinities 〉10 ppt, even when strongly N limited. In a series of mesocosm experiments using water from Narragansett Bay (Rhode Island), we manipulated top-down (grazing) and bottom-up (nutrient) factors hypothesized to exclude heterocystous cyanobacteria from estuaries. We previously reported that planktonic, heterocystous cyanobacteria grew and fixed N in the absence of grazers. Here, we focus on responses to phosphorus (P) additions and grazer manipulations. Zooplankton (Acartia sp.) populations typical of temperate zone estuaries suppressed cyanobacteria, and their influence was direct through grazing rather than indirect on nutrient stoichiometry. Cyanobacterial abundance and heterocysts were low in treatments with no external P inputs. Concentrations of dissolved inorganic P comparable to those in Narragansett Bay were obtained only in P-fertilized mesocosms. Unlike previous estuarine mesocosm experiments with P fertilization, planktonic cyanobacteria grew and fixed N in our experimental systems. However, mean cell and heterocyst abundances under the most favorable conditions (high P, low N:P, and low grazers) were much lower than in comparable freshwater experiments, with N limitation maintained. These results support the hypothesis that intrinsic growth of heterocystous cyanobacteria in saline estuaries is slower than in freshwater, and that slower growth is unlikely to be due to systematic differences in P availability. Slow growth, combined with grazing, can severely limit development of planktonic, N-fixing cyanobacterial blooms in estuaries.
    Description: This research was supported by grants from the National Science Foundation (NSF) and by an endowment given to Cornell University by David R. Atkinson. Fellowship support to F.C. was provided by NSF-sponsored graduate training grants.
    Keywords: Nitrogen fixation ; Heterocystous cyanobacteria ; Estuaries ; Nitrogen limitation ; Nitrogen and phosphorus stoichiometry ; Zooplankton grazing ; Mesocosms
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 4
    Electronic Resource
    Electronic Resource
    Effect of soil treatment with cereal straw and method of crop establishment on field pea (Pisum sativum L.) N2 fixation (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 87-95 
    Details
    ISSN: 1432-0789
    Keywords: Crop rotation ; Field pea ; Mineral N ; Nitrogen fixation ; immobilisation ; Pisum sativum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of soil incorporation with cereal straw (nil, 2.5, 5 and 10 t straw ha−1) and direct drilling on the proportion and amount of pea N derived from biological N fixation were investigated in three field experiments. Fixed N was determined by15N dilution using barley as a reference plant. The three sites were on acidic, red clay-loams in the cropping zone of southeastern Australia. Seasonal plant available soil N, as determined by the N accumulated in barley, was 31, 56 and 158 kg N ha−1, for the three sites. Incorporated straw reduced soil nitrate at sowing by 10–50 kg N ha−1 (0–30 cm), and 5 or 10 t straw ha−1 reduced barley uptake of N by 10–38 kg N ha−1. However, reducing plant available soil N was generally ineffective for increasing the N fixed by pea. Fixed N increased only at the site with the least plant-available N, and only one-third of the increase could be attributed to lower soil N uptake by pea. There was no evidence that direct drilling pea increased fixed N by decreasing crop uptake of soil N. It is proposed that a lower requirement for soil N by pea as compared to barley, and availability of mineral N beneath the soil layer treated with straw, minimise the effectiveness of straw incorporation for increasing the N fixed by pea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420226
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Effect of soil treatment with cereal straw and method of crop establishment on field pea (Pisum sativum L.) N2 fixation (1996)
    Springer
    Biology and fertility of soils 24 (1996), S. 87-95 
    Details
    ISSN: 1432-0789
    Keywords: Key words Crop rotation ; Field pea ; Mineral N ; Nitrogen fixation ; immobilisation ; Pisum sativum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of soil incorporation with cereal straw (nil, 2.5, 5 and 10 t straw ha–1) and direct drilling on the proportion and amount of pea N derived from biological N fixation were investigated in three field experiments. Fixed N was determined by 15N dilution using barley as a reference plant. The three sites were on acidic, red clay-loams in the cropping zone of southeastern Australia. Seasonal plant available soil N, as determined by the N accumulated in barley, was 31, 56 and 158 kg N ha–1, for the three sites. Incorporated straw reduced soil nitrate at sowing by 10–50 kg N ha–1 (0–30 cm), and 5 or 10 t straw ha–1 reduced barley uptake of N by 10–38 kg N ha–1. However, reducing plant available soil N was generally ineffective for increasing the N fixed by pea. Fixed N increased only at the site with the least plant-available N, and only one-third of the increase could be attributed to lower soil N uptake by pea. There was no evidence that direct drilling pea increased fixed N by decreasing crop uptake of soil N. It is proposed that a lower requirement for soil N by pea as compared to barley, and availability of mineral N beneath the soil layer treated with straw, minimise the effectiveness of straw incorporation for increasing the N fixed by pea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420226
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Influence of phosphorus or phosphorus-potassium fertilization on biomass and dinitrogen fixation of the stem-nodulating green-manure legume Sesbania rostrata in different marginally productive wetland rice soils (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 107-112 
    Details
    ISSN: 1432-0789
    Keywords: Wetland rice soils ; Nitrogen fixation ; Sesbania rostrata ; PK fertilization ; Soil Mn ; Acetylene reduction assay ; ARA ; Green manure ; N dilution method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The performance of Sesbania rostrata varies widely from site to site. This makes it difficult to predict the N yield and biomass of this plant in marginally productive soils, and to arouse the interest of farmers in green manure technology. Three consecutive pot experiments were conducted in a greenhouse at the International Rice Research Institute (IRRI) to evaluate growth, nodulation, N2 fixation (C2H2 reduction assay and 15N dilution method), and N yield of 6-week-old S. rostrata on 13 physicochemically different wetland rice soils of the Philippines and on three artificial substrates. The performance of S. rostrata on the unfertilized controls was compared with two fertilizer treatments containing either P (100 mg P kg-1 dry soil) or P+K (100 mg P kg-1 and 200 mg K kg-1 dry soil). In the control soils and substrates, the N yield of S. rostrata varied between 20 and 470 mg N per pot, with the N rate from N2 fixation ranging between 0 and 95%. In three of the nutritionally poor soils even Mn toxicity symptoms apparently occurred with S. rostrata. P application alleviated these symptoms and increased the overall N yield considerably, mainly through increased biological N2 fixation. An additional increase in N yield was obtained by the PK treatment. Multiple regression analysis between soil characteristics and the N yield of S. rostrata showed that the original level of P (Olsen-extracted) and Mn in the soil accounted for 73% of the variance in biomass production by S. rostrata among the unfertilized soils and substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336588
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The role of potassium fertilizer in nodulation and nitrogen fixation of faba bean (Vicia faba L.) plants under drought stress (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 147-150 
    Details
    ISSN: 1432-0789
    Keywords: Faba bean ; Water stress ; Nodulation ; Nitrogen fixation ; Leghaemoglobin ; Invertase ; Protease ; K fertilizer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three-week-old nodulated faba bean plants were subjected to different levels of drought stress (onehalf, one-quarter, or one-eighth field capacity) for 5 weeks. Half the stressed plants were treated with KCl at 10 mg kg-1 soil or 150 mg kg-1 soil at the beginning of the drought stress. Nodulation and nitrogenase activity were significantly decreased by increasing drought stress. Leghaemoglobin and protein contents of nodule cytosol were also severely inhibited by drought sttess. This decline was attributed to the induction of protease activity. However, carbohydrate contents of the nodule cytosol increased significantly. This accumulation was attributed to a sharp decline in invertase activity and low use of sugar by the bacteroids We conclude that harmful effects of water deficits can be alleviated by increasing K+ supplementation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336594
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Dynamics of nodulation, nitrogen fixation, nitrogen use and biomass yield over time in pot-grown Leucaena leucocephala (Lam.) de Wit (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 163-168 
    Details
    ISSN: 1432-0789
    Keywords: Leucaena ; Nodulation ; Nitrogen fixation ; Nitrogen use ; 15N ; Time course
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of nodulation, N2-fixation and N use in Leucaena leucocephala cv. K28 over time was investigated in a screenhouse at 4, 8, 12 and 16 months after planting (MAP) using the 15N-labelling method. Leucaena had a consistently increasing pattern of nodulation, dry biomass and nitrogen yield. A sharp rise in nodulation was observed between 12 and 16 MAP, whereas for biomass, N accumulation and N2-fixation, and N2-fixation, an upward surge occurred between 4 and 12 months. Nodulation, N accumulation, N2-fixation and biomass yield all peaked at 16 MAP. Along with the steady increase in N2-fixation throughout the 16-month growth period, the % N derived from the atmosphere rose from 17.9% to 61.5%, 70.1% and 74%, equivalent to 191, 1623, 2395 and 3385 mg N2 fixed plant-1 at 4, 8, 12 and 16 MAP, respectively. Nitrogen assimilation from soil and fertilizer decreased inversely to the increase in symbiotic nitrogen fixation with time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336553
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Comparison of symbiotic effectiveness of Rhizobium sp. with positive hydrogen-uptake activity compared with negative mutants in relation to nitrogen fixation in mungbean (Vigna radiata L.) (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 270-274 
    Details
    ISSN: 1432-0789
    Keywords: Mungbean ; Vigna radiata ; Nitrogen fixation ; Hydrogen uptake ; Mutation ; Nitrosoguanidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract H2 uptake activity was well distributed in Rhizobium sp. strains isolated from nodules of mung-bean (Vigna radiata L.). Two effective strains, RMP1 und RMP2, exhibiting significantly higher H2 uptake activity were subjected to mutagenesis with nitrosoguanidine. The respective mutation frequencies were 0.18 and 0.19%. Three Hup- mutants each of RMP1 und RMP2 were compared with the wild-type parent strains under pot culture experiments to evaluate the significance of the H2 uptake system in biological N2 fixation. Nodulation capabilities, plant growth characteristics, and the chlorophyll content of the leaves were significantly reduced in the plants treated with Hup- mutants. Nitrogenase activity in Hup- nodules was reduced by 8–41%. Similarly, N accumulation was also reduced singificantly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336089
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Occurrence of the endophytic diazotrophs Herbaspirillum spp. in roots, stems, and leaves, predominantly of Gramineae (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 197-200 
    Details
    ISSN: 1432-0789
    Keywords: Herbaspirillum ; Endophytes of Gramineae ; Diazotrophs ; Survival in soil ; Nitrogen fixation ; sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Since the first description of Herbaspirillum seropedicae in 1986, few data have been published on this diazotroph, possibly due to difficulties in isolating it from soil. In the present study we found that this bacterium seems to be an obligate endophyte which has been isolated from roots, stems, and leaves of a large number of samples of more than 10 different species of the Gramineae family, but only exceptionally from other plants. H. rubrisubalbicans, previously misnamed as “Pseudomonas” rubrisubalbicans, and known as a mild pathogen of sugarcane causing mottled stripe disease, confirms the endophytie habitat of this genus. This species occurs in roots, stems, and leaves of sugarcane and seems to be restricted to this crop. Inoculation of strains from both species into soil in high numbers resulted in a rapid decline in their numbers. In only 30 days the population of Herbaspirillum spp. in soil decreased below detection limits (〈100 cells g-1). When sorghum was planted in this soil, the bacteria reappeared and multiplied within the plant tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335935
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Short- and long-term effects of ammonium on photodependent nitrogen fixation in wetland rice fields of Spain (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 353-357 
    Details
    ISSN: 1432-0789
    Keywords: Key words Acetylene reduction assay ; Anabaena sp. ; Ammonium ; Cyanobacteria ; Nitrogen fixation ; Wetland rice fields ; Nitrogenase activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Short- and long-term experiments were conducted in the rice fields of Valencia, Spain, to determine the ecological significance of ammonium on nitrogen fixation. A significant inhibition of nitrogenase activity by ammonium, at concentrations higher than 0.5mM, was observed after 8h of incubation in short-term experiments done with a bloom of the N2-fixing cyanobacterium Anabaena sp. In a second set of short-term experiments for in situ assays of nitrogenase activity in the field, a significant correlation between nitrogenase activity and the number of N2-fixing cyanobacteria in soil was found. No significant inhibition of nitrogenase activity by ammonium at concentrations up to 2mM was observed in these assays after 24h of incubation. This lack of inhibition was probably due to the rapid decrease in ammonium content in the flood water. Only 5% of the ammonium initially added remained in the water 24h later. In the long-term experiments, nitrogenase activity was assayed in plots fertilized with 0, 70 and 140kgNha–1, over the cultivation cycle, for 5 years. A partial inhibition of nitrogenase activity by deep-placed N fertilizers was observed. Differences were only significant in 2 years. Mean results from 5 years only showed significant differences between plots fertilized with 0 and 140kgNha–1. The partial inhibition of nitrogenase activity by ammonium increased over the cultivation cycle. Inhibition was only significant in September, at the end of the cultivation cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050257
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Phenotypic grouping of Brazilian Bradyrhizobium strains which nodulate soybean (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 407-415 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsBradyrhizobium japonicum ; Bradyrhizobium elkanii ; Genetic variability ; Glycine max ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Several years of research have shown that there is a high genetic and physiological variability among Bradyrhizobium japonicum strains, culminating in a subdivision into two bacterial genotypes, and the description of the new species B. elkanii. In Brazil, large-scale soybean inoculation started in 1960 and today 15 million doses of inoculants are sold per year for an estimated area of 12 million ha. Efforts have been made to find strains able to fix high amounts of N2 under Brazilian soil conditions, but few laboratories cover basic studies on N2 fixation, such as strain classification into the two Bradyrhizobium species. In this study several characteristics of 40 soybean Bradyrhizobium strains, including 4 reference strains of B. japonicum (genotype I) species, 3 of B. elkanii (genotype II) and 1 of a mixed genotype were evaluated. The parameters analysed in vitro were: colony morphology, serological grouping, intrinsic resistance to antibiotics, synthesis of indole acetic acid, expression of hydrogenase activity and growth in a medium enriched with asparagine. In vivo, analyses performed included the nodulation of Rj 4 soybean cultivar Hill and the detection of symptoms caused by rhizobitoxine. These evaluations allowed a phenotypic grouping which positioned most of the strains utilized in Brazilian inoculants and studies, as well as some new strains isolated from the Cerrado region, within the species B. elkanii. However, environmental stresses and adaptation of Bradyrhizobium strains to the soil caused a large physiological and genetic variability in some isolates from the Cerrado soils in relation to the putative parental strain introduced 15 years ago, placing these isolates in an intermediate position between the two Bradyrhizobium species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050333
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Nodulation pattern and acetylene reduction (nitrogen fixation) activity of some highland and lowland Acacia species of Ethiopia (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 60-64 
    Details
    ISSN: 1432-0789
    Keywords: Key words Acacia spp. ; Bradyrhizobium ; Rhizobium ; Nitrogen fixation ; Nitrogen accumulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Endosymbionts from the Ethiopian highland acacia species Acacia abyssinica, A. negrii and A. etbaica, and the lowland species A. nilotica, A. prasinata, A.senegal, A. seyal, A. tortilis and Faidherbia (Acacia) albida were isolated and characterized. Seven tree species were found to be nodulated by species of both Rhizobium and Bradyrhizobium. F. (Acacia) albida and A. senegal were nodulated by only Bradyrhizobium or Rhizobium, respectively. In A. abyssinica, both genera were isolated from the same nodule, whereas in A. nilotica and A. tortilis, both strains were isolated from different nodules of the same plant. The nitrogen fixation (acetylene reduction) activities varied considerably and showed no correlation with the nitrogen content of the plant. Highland species were as effective as lowland plants, thus demonstrating good potential for soil reclamation. The endosymbionts isolated proved rather promiscuous, efficiently nodulating other Acacia spp. and some tropical grain legumes, but did not nodulate temperate legumes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050400
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Nitrogen fixation capacity and nodule occupancy by Bradyrhizobium japonicum and B. elkanii strains (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 393-399 
    Details
    ISSN: 1432-0789
    Keywords: Key words Bradyrhizobium japonicum ; Bradyrhizobium elkanii ; Competitiveness ; Nitrogen fixation ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In a previous study soybean Bradyrhizobium strains, used in Brazilian studies and inoculants over the last 30 years, and strains adapted to the Brazilian Cerrados, a region frequently submitted to environmental and nutritional stresses, were analyzed for 32 morphological and physiological parameters in vivo and in vitro. A cluster analysis allowed the subdivision of these strains into species Bradyrhizobium japonicum, Bradyrhizobium elkanii and a mixed genotype. In this study, the bacteria were analyzed for nodulation, N2 fixation capacity, nodule occupancy and the ability to increase yield. The goal was to find a relationship between the strain groups and the symbiotic performance. Two strains of Brazilian B. japonicum showed higher rates of N2 fixation and nodule efficiency (mg of N mg–1 of nodules) under axenic conditions. These strains also showed greater yield increases in field experiments when compared to B. elkanii strains. However, no differences were detected between B. japonicum and B. elkanii strains when comparing nodule occupancy capacity. The adapted strains belonging to the serogroup B. elkanii SEMIA 566, most clustered in a mixed genotype, were more competitive than the parental strain, and some showed a higher capacity of N2 fixation. Some of the adapted strains, such as S-370 and S-372, have shown similar N2 fixation rates and nodulation competitiveness to two Brazilian strains of B. japonicum. This similarity demonstrates the possibility of enhancing N2 fixing ability, after local adaptation, even within B. elkanii species. Differences in the DNA profiles were also detected between the parental SEMIA 566 and the adapted strains by analyses with the ERIC and REP-PCR techniques. Consequently, genetic, morphological and physiological changes can be a result of adaptation of rhizobia to the soil. This variability can be used to select strains capable of increasing the contribution of N2 fixation to soybean nutrition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050449
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Renodulation and characterization of Rhizobium isolates from cicer milkvetch (Astragalus cicer L.) (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 169-174 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsAstragalus cicer ; Nodulation ; DNA ; Milkvetch ; Nitrogen fixation ; Forage legume ; Rhizobium spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In 1993 and 1994, 12 bacterial isolates were isolated from root nodules of cicer milkvetch (Astragalus cicer). In the tests for nodulation of A. cicer by these bacterial isolates, five were found to form hypertrophic structures, while only two formed true nodules. These true nodules were formed in a sterilized soil system. This system might be able to act as a DNA donor to provide residual DNA to other microbes in the soil. The rhizobial isolates were thought to have lost genetic material crucial to nodulation during the isolation process. This hypothesis was supported by an experiment in which isolate B2 was able to nodulate A. cicer in vermiculite culture after being mixed with heat-killed rhizobia, Rhizobium leguminosarum bv. trifolii and R. loti. The nodulation would not occur in vermiculite culture system without the heat-killed rhizobia. Based on the biochemical data, the B2 and 9462L, which formed true nodules with A. cicer, were closely related. The rhizobia type cultures that nodulate A. cicer include Bradyrhizobium japonicum, Rhizobium leguminosarum bv. trifolii, R. leguminosarum bv. viceae, and R. loti. All of these rhizobia were from different cross-inoculation groups. The B2 and 9462L isolates could only nodulate Medicago sativa, Phaseolus vulgaris, and Melilotus officinalis, but not these species within the genus from which they were isolated: Astragalus. The traditional cross-inoculation group concept obviously does not fit well in the classification of rhizobia associated with Astragalus. The rhizobia isolated from A. cicer can be quite different, and the rhizobia able to renodulate A. cicer also quite diverse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050299
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Dual inoculation with strains of Bradyrhizobium japonicum and Azospirillum brasilense to improve growth and biological nitrogen fixation of soybean (Glycine max L.) (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 317-322 
    Details
    ISSN: 1432-0789
    Keywords: Key words Soybean ; Isotope dilution ; Nitrogen fixation ; Bradyrhizobium japonicum ; Soil sterilization ; 15N ; Azospirillum brasilense ; Bacterial inoculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of inoculation with Bradyrhizobium japonicum and Azospirillum brasilense strains on the growth of soybean were evaluated with regard to the estimation of N2 fixation using the 15N isotope dilution technique. Inoculation, in general, increased the dry mass of soybean as well as nitrogen content. Dual inoculation with a mixture of B. japonicum and A. brasilense strains was superior over single inoculation with B. japonicum. Nitrogen fixed (Ndfa) varied according to inoculant and soil conditions. Percentages of nitrogen derived from air (% Ndfa) using a non-nodulating isoline were 72% and 76% for B. japonicum and B. japonicum plus A. brasilense, respectively, in non-sterile soil. A similar but higher trend was recorded in sterilized soil, in which the percentages of N2 fixed were 81% and 86% for single and dual inoculation, respectively. The correlation coefficient between N2 fixed and N uptake (r=0.94) and dry mass (r=0.89) was significant. Application of special bacterial inoculants in agricultural systems of Egypt seems to be a promising technology and could be used for improving soybean growth as well as soil fertility, thus minimizing environmental pollution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050250
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Influence of long-term conservation tillage on soil and rhizosphere microorganisms (1999)
    Springer
    Biology and fertility of soils 29 (1999), S. 81-86 
    Details
    ISSN: 1432-0789
    Keywords: Key words Soil tillage ; Rhizosphere microorganisms ; Cereals ; Nitrogen fixation ; Gaeumanomyces graminis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In long-term field experiments on sandy loam and loamy sand soils, the influence of conservation and conventional tillage on soil and rhizosphere microorganisms was studied. Conservation tillage stimulated rhizosphere bacteria on winter wheat, winter barley, winter rye and maize in different soil layers. Particularly the populations of Agrobacterium spp. and Pseudomonas spp. were increased. On the sandy loam, N2 fixation and nodulation of pea plants were significantly increased. No influence of different soil tillage was determined on the colonization of the rhizosphere by mycorrhiza and saprophytic fungi. Stubble residues infected with Gaeumanomyces graminis were infectious for a longer time on the soil surface than after incorporation into the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050528
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Fate of blue-green algae in the food web of flooded rice-field ecosystems (1999)
    Springer
    Biology and fertility of soils 29 (1999), S. 141-145 
    Details
    ISSN: 1432-0789
    Keywords: Key words Blue-green algae ; Nitrogen fixation ; Rice ecosystem ; Zooplankton ; Benthos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  As part of an integrated pest management project to study the role blue-green algae (BGA) may play in the food web of rice-field ecosystems, 14C-labelled filamentous and monocellular BGA were used as food for fish, zooplankton and benthic fauna in artificial rice fields in the form of three aquaria. 14C present in the organisms was then traced by liquid scintillation to follow the manner in which the labelled BGA were consumed by different organisms. In this study the grazing rate of fish (mud carp) was compared to that of benthic organisms and zooplankton. It was found that fish consumed the BGA at the fastest rates and in the largest amounts, followed by the benthic species and zooplankton. It was also found that filamentous BGA were consumed in higher amounts than monocellular BGA. The importance of grazing in nutrient recycling is emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050536
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Diurnal and seasonal patterns of nitrogenase activity of red alder in comparison with white clover in silvopastoral agroforestry systems (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 267-270 
    Details
    ISSN: 1432-0789
    Keywords: Key words Red alder ; White clover ; Nitrogenase activity ; Acetylene reduction assay ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Simultaneous measurements were made to assess the diurnal and seasonal patterns of nitrogenase activity of red alder (Alnus rubra Bong.) and white clover (Trifolium repens L.) growing together in a silvopastoral agroforestry system using the acetylene reduction assay. Diurnal measurements were made in the summer and autumn at 3-h intervals whereas seasonal nitrogenase activity was assessed based on observations made at midday in July, September and January to represent the summer, autumn and winter seasons, respectively. No obvious diurnal patterns of nitrogenase activity were found in either red alder or white clover in summer and no significant variations in nitrogenase activity were observed between day and night. However, in autumn, pronounced diurnal patterns were observed in both species. Significantly higher rates of nitrogenase activity per unit dry weigh (dwt) of nodules were detected at 1500 hours in red alder, whereas, in white clover, significantly higher rates were obtained at 2100 hours. There was no significant correlation between diurnal nitrogenase activity and air temperature, photosynthetically active radiation and soil temperature at 10 cm depth in either red alder or white clover. Seasonal rates of nitrogenase activity showed significantly higher activity in summer, which subsequently decreased in autumn, to reach very low levels in the winter. The rates of nitrogenase activity of white clover were consistently higher than those of red alder both diurnally and seasonally. In the three seasons sampled, the average nitrogenase activity for white clover was 66.42 μmol C2H4 g dwt–1 h–1, which was 3.5 times higher than the 18.67 μmol C2H4 g dwt–1 h–1 obtained for red alder.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050492
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Relationships between soil aggregation and mycorrhizae as influenced by soil biota and nitrogen nutrition (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 356-363 
    Details
    ISSN: 1432-0789
    Keywords: Key words Arbuscular mycorrhiza ; Collembola ; Nitrogen fertilization ; Nitrogen fixation ; Soil aggregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effect of the form of N nutrition on soil stability is an important consideration for the management of sustainable agricultural systems. We grew soybean [Glycine max (L.) Merr.] plants in pot cultures in unsterilized soil, and treated them by (1) inoculating them with Bradyrhizobium japonicum, fertilizing with (2) nitrate or (3) ammonia, or (4) by providing only minimum N amendment for the controls. The soils were sampled at 3-week intervals to determine changes in water-stable soil aggregates (WSA), soil pH, the development of roots, arbuscular mycorrhizal (AM) soil and root colonization, and selected functional groups of soil bacteria. The soil fauna was assayed at the end of the experiment (9 weeks). WSA was correlated positively with root and AM soil mycelium development, but negatively with total bacterial counts. Soil arthropod (Collembola) numbers were negatively correlated with AM hyphal length. Soils of nodulated and ammonia-fertilized plants had the highest levels of WSA and the lowest pH at week 9. Sparse root development in the soils of the N-deficient, control plants indicated that WSA formation was primarily influenced by AM hyphae. The ratio of bacterial counts in the water-stable versus water-unstable soil fractions increased for the first 6 weeks and then declined, while counts of anaerobic bacteria increased with increasing WSA. The numbers of soil invertebrates (nematodes) and protozoans did not correlate with bacterial counts or AM soil-hyphal lengths. Soil pH did not affect mycorrhiza development, but actinomycete counts declined with decreasing soil pH. AM fungi and roots interacted as the factors that affect soil aggregation, regardless of N nutrition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050504
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Adaptation of green manure legumes to adverse conditions in rice lowlands (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 243-248 
    Details
    ISSN: 1432-0789
    Keywords: Key words Adverse soil conditons ; Aeschynomene ; Green manure ; Lowland rice ; Nitrogen fixation ; Sesbania ; Forming system development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Poor adoption of sustainable pre-rice green manure technology by lowland farmers is frequently associated with unreliable legume performance under adverse environmental conditions such as marginal soils, short photoperiod, and unfavorable hydrology. A series of field and microplot experiments were conducted at the International Rice Research Institute (IRRI) in 1991 and 1992 to screen and evaluate 12 promising flood-tolerant legumes for adaptation (N accumulation and biological N2 fixation) to a range of environmental stresses, frequently encountered in rice lowlands. Legumes belonging to the genera Sesbania and Aeschynomene were grown for 8 weeks at 10×10 cm spacing: (1) in a fertile control soil and in four marginally productive irrigated lowland rice soils (sandy Entisol, P-deficient Inceptisol, acid Ultisol, and saline Mollisol); (2) during short- (11.7 h) and long-day (12.3 h) seasons in a favorable irrigated lowland soil; and (3) in an aerobic soil (drought-prone rain-fed lowland) and a deep-flood-prone lowland soil (1 week seedling submergence). A large variability in N accumulation was observed among legume species and across different environments, ranging from less than 1 to over 70 mg N plant–1. The nitrogen derived from the atmosphere (Ndfa) accounted on average for 82% of total N accumulation. Sesbania virgata was least affected by unfavorable soil conditions but its Ndfa was the lowest among the tested species (less than 60%). Stem nodule formation did not convey a significant advantage to legumes grown under adverse soil conditions. However, flooding reduced N2 fixation less in stem-nodulating than in solely root-nodulating species. Most species drastically reduced N accumulation under short-day conditions. Aeschynomene afraspera and S. speciosa were least affected by photoperiod. The considerable genetic variability in the germplasm screened allows the selection of potentially appropriate legumes to most conditions studied, thus increasing N accumulation in green manures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335951
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Soil surface disturbances in cold deserts: effects on nitrogenase activity in cyanobacterial-lichen soil crusts (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 362-367 
    Details
    ISSN: 1432-0789
    Keywords: Cryptobiotic ; Cryptogamic ; Microphytic ; Microbiotic ; Deserts ; Nitrogen fixation ; Nutrient cycling ; Lichens ; Microcoleus vaginatus ; Collema tenax ; Heterocysts ; Acetylene reduction assay ; ARA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cyanobacterial-lichen soil crusts can be a dominant source of nitrogen for cold-desert ecosystems. Effects of surface disturbance from footprints, bike and vehicle tracks on the nitrogenase activity in these crusts was investigated. Surface disturbances reduced nitrogenase activity by 30–100%. Crusts dominated by the cyanobacterium Microcoleus vaginatus on sandy soils were the most susceptible to disruption; crusts on gypsiferous soils were the least susceptible. Crusts where the soil lichen Collema tenax was present showed less immediate effects; however, nitrogenase activity still declined over time. Levels of nitrogenase activity reduction were affected by the degree of soil disruption and whether sites were dominated by cyanobacteria with or without heterocysts. Consequently, anthropogenic surface disturbances may have serious implications for nitrogen budgets in these ecosystems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335908
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Soil surface disturbances in cold deserts: effects on nitrogenase activity in cyanobacterial-lichen soil crusts (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 362-367 
    Details
    ISSN: 1432-0789
    Keywords: Key words Cryptobiotic ; Cryptogamic ; Microphytic ; Microbiotic ; Deserts ; Nitrogen fixation ; Nutrient ; cycling ; Lichens ; Microcoleus vaginatus ; Collema tenax ; Heterocysts ; Acetylene reduction assay ; ARA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cyanobacterial-lichen soil crusts can be a dominant source of nitrogen for cold-desert ecosystems. Effects of surface disturbance from footprints, bike and vehicle tracks on the nitrogenase activity in these crusts was investigated. Surface disturbances reduced nitrogenase activity by 30–100%. Crusts dominated by the cyanobacterium Microcoleus vaginatus on sandy soils were the most susceptible to disruption; crusts on gypsiferous soils were the least susceptible. Crusts where the soil lichen Collema tenax was present showed less immediate effects; however, nitrogenase activity still declined over time. Levels of nitrogenase activity reduction were affected by the degree of soil disruption and whether sites were dominated by cyanobacteria with or without heterocysts. Consequently, anthropogenic surface disturbances may have serious implications for nitrogen budgets in these ecosystems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050184
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Survival and symbiotic properties of Bradyrhizobium japonicum in the presence of thiram: isolation of fungicide resistant strains (1997)
    Springer
    Biology and fertility of soils 26 (1997), S. 141-145 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsBradyrhizobium japonicum ; Nodulation ; Nitrogen fixation ; Soybean ; Thiram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The fungicide thiram, widely used as a chemical seed protectant, induces a strong inhibition of primary nodulation in the crown zone of soybean roots. The present work reports on the isolation of Bradyrhizobium japonicum strains resistant to thiram, some of which (T3B, A86 and A2) maintained their capacity for nodulation and were still efficient symbionts, but some (A1, C1 and C6) lost the ability to stimulate nodulation. Characterization tests such as growth at different pH, denitrifying ability, salt tolerance, production of siderophores and phosphate solubilization were performed on the resistant strains. Inoculants produced from these strains could be appropriate for use with thiram-treated seeds, without causing a loss of bacteria viability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050357
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Natural abundance of 15N in sweet potato, pumpkin, sorghum and castor bean: possible input of N2-derived nitrogen in sweet potato (1997)
    Springer
    Biology and fertility of soils 26 (1997), S. 152-154 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsCucurbita moschata ; Ipomoea batatas ; Nitrogen fixation ; δ15N method ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two combinations of plant species, sweet potato (three cultivars) and pumpkin, and sweet sorghum (three cultivars) and castor bean were grown separately in three plots of alluvial soil from June to September 1996. The shoots (leaves plus stems) of sweet potato and pumpkin, and the whole tops (leaves plus stems and grains) of sweet sorghum and castor bean were harvested twice, once in August and once in September in order to analyze their natural abundance of 15N (δ15N). The δ15N values of two of the varieties of sweet potato harvested in September were significantly lower than those of pumpkin, while δ15N values of sweet potato and pumpkin harvested in August, as well as those of sweet sorghum and castor bean harvested in August and September, did not significantly differ. The lower δ15N values observed in the September-harvested sweet potato may indicate that as much as 40% of the N intake of this species is derived from dinitrogen. This species is known to have a high ability to take up N from undefined sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050359
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Adaptation of green manure legumes to adverse conditions in rice lowlands (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 243-248 
    Details
    ISSN: 1432-0789
    Keywords: Adverse soil conditons ; Aeschynomene ; Green manure ; Lowland rice ; Nitrogen fixation ; Sesbania ; Forming system development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Poor adoption of sustainable pre-rice green manure technology by lowland farmers is frequently associated with unreliable legume performance under adverse environmental conditions such as marginal soils, short photoperiod, and unfavorable hydrology. A series of field and microplot experiments were conducted at the International Rice Research Institute (IRRI) in 1991 and 1992 to screen and evaluate 12 promising flood-tolerant legumes for adaptation (N accumulation and biological N2 fixation) to a range of environmental stresses, frequently encountered in rice lowlands. Legumes belonging to the genera Sesbania and Aeschynomene were grown for 8 weeks at 10×10 cm spacing: (1) in a fertile control soil and in four marginally productive irrigated lowland rice soils (sandy Entisol, P-deficient Inceptisol, acid Ultisol, and saline Mollisol); (2) during short- (11.7h) and long-day (12.3 h) seasons in a favorable irrigated lowland soil; and (3) in an aerobic soil (drought-prone rain-fed lowland) and a deep-flood-prone lowland soil (1 week seedling submergence). A large variability in N accumulation was obsersed among legume species and across different environments, ranging from less than 1 to over 70 mg N plant-1. The nitrogen derived from the atmosphere (Ndfa) accounted on average for 82% of total N accumulation. Sesbania virgata was least affected by unfavorable soil conditions but its Ndfa was the lowest among the tested species (less than 60%). Stem nodule formation did not convey a significant advantage to legumes grown under adverse soil conditions. However, flooding reduced N2 fixation less in stem-nodulating than in solely root-nodulating species. Most species drastically reduced N accumulation under short-day conditions. Aeschynomene afraspera and S. speciosa were least affected by photoperiod. The considerable genetic variability in the germplasm screened allows the selection of potentially appropriate legumes to most conditions studied, thus increasing N accumulation in green manures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335951
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Nitrogen use in maize-grain legume cropping systems in semi-arid Kenya (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 57-62 
    Details
    ISSN: 1432-0789
    Keywords: Nitrogen use ; Nitrogen fertilizer recovery ; Zea mays ; Phaseolus vulgaris ; Vigna unguiculata ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Locally suitable cultivars of maize, beans, and cowpeas were grown in field experiments for four seasons in semi-arid Kenya. For three seasons, the dry matter production and grain yield of maize and beans were not increased by N fertilizer additions up to 120 kg N ha-1. Fertilizer recoveries measured by 15N isotope dilution techniques were low, less than 20%. Inoculated and uninoculated beans failed to fix N2. By contrast the cowpea derived 50% of its N from fixation, equivalent to 197 kg N ha-1. The N content of the grain generally exceeded 40 kg N ha-1, and the N content of the seeds from the grain legumes were greater than those from the cereals. Large inputs of N fertilizer or N by fixation are required if maize-grain legume cropping system in semiarid Kenya are to be sustained in the long term.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307842
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Nodulation of African yam bean (Sphenostylis stenocarpa) by Bradyrhizobium sp. isolated from Erythrina brucei (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 209-210 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsBradyrhizobium ; Sphenostylis stenocarpa ; Nitrogen fixation ; Soil reclamation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract African yam bean (Sphenostylis stenocarpa), which is widely cultivated in Africa because of its growth capability on marginal soils, was nodulated by an endosymbiont (characterized and designed Bradyrhizobium sp. AUEB20) isolated from the Ethiopian tree Erythrina brucei with the formation of a small number of large, indeterminate N2-fixing nodules. In contrast, 24 other isolates from Ethiopian woody legumes were ineffective. Strain AUEB20 promiscuously nodulated a number of tropical legumes, but none out of five European crop plants tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050305
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Diversity, adaptation and activity of the bacterial flora in saline environments (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 211-223 
    Details
    ISSN: 1432-0789
    Keywords: Key words Bacterial flora ; Salt-affected soils ; Salt marshes ; Osmotic adjustment ; Microbial activity ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Saline environments have a natural bacterial flora, which may play a significant role in the economy of these habitats. The natural saline environments (usually containing salinity equivalent to 4–30% NaCl) are aquatic (e.g. salt marshes) or terrestrial (e.g. saline lands). Saline environments include an increasing area of salt-affected cultivated soils throughout the world. These environments contain various ions which may interfere with uptake of water and which may be toxic to a large number of organisms. Saline environments harbour taxonomically diverse bacterial groups, which exhibit modified physiological and structural characteristics under the prevailing saline conditions. The majority of these bacteria can osmoregulate by synthesizing specific compatible organic osmolytes such as glutamine, proline and glycine betaine and a few of them accumulate inorganic solutes such as Na+, K+ and Mg2+. The morphology of the bacteria is usually modified, cells are usually elongated, swollen and showing shrinkage, in addition to changes in the cell and cytoplasmic volume. The chemical composition of membranes may also occasionally be modified, and the synthesis pattern of proteins, lipids, fatty acids and polysaccharides may change with a moderate increase in salinity. However, ultrastructural alterations in cells of halophilic bacteria have not been reported, and profound changes in cellular properties of these bacteria only occur at concentrations above 2MNaCl. Evidence has accumulated that the bacteria are essential elements in the saline environment because of their activity such as degradation of plant remains, nitrogen fixation and production of active metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050306
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    Free-radical-induced mutation vs redox regulation: Costs and benefits of genes in organelles (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 482-492 
    Details
    ISSN: 1432-1432
    Keywords: Aging ; Chloroplasts ; Mitochondria ; Cell evolution ; Cytoplasmic genomes ; Gene transfer ; Redox regulation ; Free radical mutagenesis ; Nitrogen fixation ; Endosymbiosis ; Mutation frequency ; Uniparental inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The prokaryotic endosymbionts that became plastids and mitochondria contained genes destined for one of three fates. Genes required for free-living existence were lost. Most genes useful to the symbiosis were transferred to the nucleus of the host. Some genes, a small minority, were retained within the organelle. Here we suggest that a selective advantage of movement of genes to the nucleus is decreased mutation: plastids and mitochondria have high volume-specific rates of redox reactions, producing oxygen free radicals that chemically modify DNA. These mutations lead to synthesis of modified electron carriers that in turn generate more mutagenic free radicals—the “vicious circle” theory of aging. Transfer of genes to the nucleus is also advantageous in facilitating sexual recombination and DNA repair. For genes encoding certain key components of photosynthesis and respiration, direct control of gene expression by redox state of electron carriers may be required to minimize free radical production, providing a selective advantage of organelle location which outweighs that of location in the nucleus. A previous proposal for transfer of genes to the nucleus is an economy of resources in having a single genome and a single apparatus for gene expression, but this argument fails if any organellar gene is retained. A previous proposal for the retention of genes within organelles is that certain proteins are organelle-encoded because they cannot be imported, but there is now evidence against this view. Decreased free radical mutagenesis and increased sexual recombination upon transfer to the nucleus together with redox control of gene expression in organelles may now account for the slightly different gene distributions among nuclei, plastids, and mitochondria found in major eukaryote taxa. This analysis suggests a novel reason for uniparental inheritance of organelles and the evolution of anisogametic sex, and may also account for the occurrence of nitrogen fixation in symbionts rather than in nitrogen-fixing organelles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02352278
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Plant growth, leaf water potential, nitrogenase activity and nodule anatomy in Leucaena leucocephala as affected by water stress and nitrogen availability (1997)
    Springer
    Trees 12 (1997), S. 42-48 
    Details
    ISSN: 0931-1890
    Keywords: Key words Drought stress ; Fertilization ; Irrigation ; Nitrogen fixation ; Nodule structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effects of water stress and nitrogen availability on leaf water potential, nitrogenase activity, and growth was studied in a pot experiment with Leucaena leucocephala seedlings. Water stress was imposed on fertilized and unfertilized plants after inoculation with Rhizobium. Non-inoculated seedlings were used as control plants. Water stress lowered leaf water potential in all seedlings after 14 days of treatment. In inoculated seedlings, fertilized plants were more sensitive to water stress than unfertilized plants, as shown by a higher leaf water potential in plants of the latter treatment. Uninoculated and fertilized seedlings were most affected by water stress. This indicates that Rhizobium might increase stress tolerance in unfertilized seedlings at moderate water stress levels. The combined effects of water stress and applied fertilizers resulted in cessation of nitrogen fixation. Nitrogen fixation came to a complete stop after 22 days of water stress in fertilized seedlings. The different treatments were accompanied by anatomical changes of nodule structure. It is hypothesised that the leaf water potential may be used as an indicator to predict changes in nitrogen fixation in legume tree/shrub species during periods of water stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009695
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Microclimatic parameters influencing nitrogen fixation in the phyllosphere in a Costa Rican premontane rain forest (1998)
    Springer
    Oecologia 117 (1998), S. 9-18 
    Details
    ISSN: 1432-1939
    Keywords: Key words Costa Rica ; Cyanobacteria ; Microclimate ; Nitrogen fixation ; Phyllosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The acetylene reduction method was used to measure nitrogen fixation in the phyllosphere of attached leaves of different phorophytes under natural conditions in a premontane rain forest in Costa Rica. Maximum rates of nitrogen fixation (26 ng N · cm−2 leaf area · h−1) – mainly due to the activity of two species of Scytonema (Cyanobacteria) – were measured in the rainy season in bright sunlight. Rates of nitrogen fixation were correlated with the leaf area covered by Scytonema. In periods without precipitation the fixation activity decreased to zero within 2–3 days. As long as the epiphylls were sufficiently supplied with water, other microclimatic factors like temperature and light intensity also influenced nitrogen fixation rates, but to a lesser extent. Relative humidity and species of phorophyte showed no direct influence. It was concluded that the most important factor for nitrogen fixation in the phyllosphere was the availability of liquid water. Linking these results to meteorological data, the input of nitrogen by biological nitrogen fixation in the phyllosphere in the investigation area was estimated to be as much as 1.6 ± 0.8 kg N · ha−1 · year−1 per unit of leaf area index (LAI). For an LAI of 2 for the understory the nitrogen input would vary between 2 and 5 kg N · ha−1 · year−1. This work also demonstrates the importance of detailed knowledge of variation in microclimate throughout the year as a basis for extrapolation of the annual nitrogen input.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050625
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    The unique root-nodule symbiosis between Rhizobium and the aquatic legume, Neptunia natans (L. f.) Druce (1995)
    Springer
    Planta 196 (1995), S. 311-320 
    Details
    ISSN: 1432-2048
    Keywords: Infection ; Neptunia (root nodules) ; Nitrogen fixation ; Nodulation ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the development of the aquatic N2-fixing symbiosis between Rhizobium sp. (itNeptunia) and roots of Neptunia natans L. f. (Druce) (previously N. oleracea Lour.) under natural and laboratory conditions. When grown in its native marsh habitat, this unusual aquatic legume does not develop root hairs, the primary sites of rhizobial infection for most temperate legumes. Under natural conditions, the aquatic plant floats and develops nitrogen-fixing nodules at emergence of lateral roots on the primary root and on adventitious roots at stem nodes, but not from the stem itself. Cytological studies using various microscopies revealed that the mode of root infection involved an intercellular route of entry followed by an intracellular route of dissemination within nodule cells. After colonizing the root surface, the bacteria entered the primary root cortex through natural wounds caused by splitting of the epidermis and emergence of young lateral roots, and then stimulated early development of nodules at the base of such roots. The bacteria entered the nodule through pockets between separated host cells, then spread deeper in the nodule through a narrower intercellular route, and eventually evoked the formation of infection threads that penetrated host cells and spread throughout the nodule tissue. Bacteria were released from infection droplets at unwalled ends of infection threads, became enveloped by peribacteroid membranes, and transformed into enlarged bacteroids within symbiosomes. In older nodules, the bacteria within symbiosomes were embedded in an unusual, extensive fibrillar matrix. Cross-inoculation tests of 18 isolates of rhizobia from nodules of N. natans revealed a host specificity enabling effective nodulation of this aquatic legume, with lesser affinity for Medicago sativa and Ornithopus sp., and an inability to nodulate several other crop legume species. Acetylene reduction (N2 fixation) activity was detected in nodules of N. natans growing in aquatic habitats under natural conditions in Southern India. These studies indicate that a specific group of Rhizobium sp. (Neptunia) occupies a unique ecological niche in aquatic environments by entering into a N2-fixing root-nodule symbiosis with Neptunia natans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201390
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380825
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Enhanced denitrification in plots of N2-fixing faba beans compared to plots of a non-fixing legume and non-legumes (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 77-83 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Field experiment ; Acetylene inhibition technique ; Nitrate ; Soil moisture ; Vicia faba ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Denitrification rates were studied using the C2H2 inhibition technique in a 2-year field experiment within plots of nodulated and non-nodulated faba beans, ryegrass, and cabbage. Denitrification rates ranged from 14.40 to 0.02 ng N2O−N g−1 soil dry weight h−1. Mean denitrification increased fourfold in plots of N2−fixing Vicia faba compared to non-nodulated V. faba mutant F48, Lolium perenne, and Brassica oleracea. The results with and without C2H2 treatment indicate that in the field the major part of this enhanced denitrification led to the endproduct N2 rather than to the ozone-degrading N2O. Higher denitrification rates of plots with N2−fixing plants in September seemed to be caused by an increase in soil NO inf3 sup- of about 20 kg ha−1 found between July and August. Soil NO inf3 sup- and soil moisture explained 67% of the variation in denitrification rates of the different soil samples over the growing seasons in the 2 years. Soil moisture explained 44% of the variation for soil planted with N2−fixing plants and 62% for soil planted with non-fixing plants. Positive exponential relationships were obtained between denitrification rates and soil nitrate (r=0.71) and soil moisture (r=0.82).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335996
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Endophytic establishment of Azorhizobium caulinodans through auxin-induced root tumors of rice (Oryza sativa L.) (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 293-302 
    Details
    ISSN: 1432-0789
    Keywords: Key words Ammonium excretion ; Azorhizobium caulinodans ; Auxine ; 2 ; 4-Dichlor-phenoxy-acetic acid ; Nitrogen fixation ; Paranodulation ; Rice ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice seedlings developed nodule-like tumors (para-nodules) along primary and secondary roots when treated with the auxin 2,4-dichlor-phenoxy-acetic acid (2,4-D). Histologically, these tumors appeared as cancerous out-grown lateral-root primordes and were thus comparable with stem nodules of the legume Sesbania rostrata. Azorhizobium caulinodans (a diazotroph known as a specific endophyte of Sesbania rostrata) was introduced and became established inside rice para-nodules and in root tissues around tumor bases. The infection with A. caulinodans followed a typical “crack-entry” invasion at places where para-nodule tumors had emerged through the root cortex and epidermis. The bacteria settled with high cell densities in intercellular spaces of the induced tumors and betwen root cortical cells. Infection of plant cells took place both in the epidermis and in cortical tissue. Intracellularly established A. caulinodans was found inside the cytoplasm, surrounded by membrane-like structures. N2 fixation by tumor-inhabiting Azorhizobium sp. was increased at low O2 tensions (1.5–3 kPa) compared with an untreated control. Only a little activity remained at O2 tensions of 5 kPa and above. The present results confirm that root-tumor induction offers a suitable method of establishing diazotrophs endophytically in the roots of gramineous crops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334906
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Tree fallows: A comparison between five tropical tree species (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 50-56 
    Details
    ISSN: 1432-0789
    Keywords: Agroforestry ; 15N ; Nitrogen fixation ; Phenolics ; 13C ; Tree fallows
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The natural abundance of 15N and 13C, conventional soil analyses, and biomass production by maize were used to study the influence of five tropical tree species on soils and their fertility. The experiment was conducted in Morogoro, Tanzania, to compare Cassia (Senna) siamea, Eucalyptus camaldulensis, E. tereticornis (all non-N2-fixing), Leucaena leucocephala, Prosopis chilensis (both N2-fixing), and a grass fallow. Maize biomass production, which was correlated with N uptake (P=0.001), was higher on soils from plots with 5-year-old Leucaena and Prosopis spp. compared to the grass fallow, while other tree species had less favourable effects on maize growth. The per cent N was higher in soil and δ15N of soil total N was lower under Prosopis sp. compared to soil under other tree species, which suggests an input from N2 fixation by Prosopis sp. A transfer of fixed N to maize or to understorey grass species was, however, not indicated by the 15N natural abundance. Prosopis sp. contributed more C to the soil than the other four tree species; the difference in δ13C between soils from Prosopis sp. plots and from grass fallow plots showed that the tree contributed 11% to the total C of the soil over a period of 8 years. The leaves of the N2-fixing species had a low ratio of lignin+phenols to N, and maize growth was negatively correlated with this parameter. The Eucalyptus spp. had leaves with a high lignin+phenols to N ratio, contributed very little C to the soil, and lowered the soil pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335818
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Occurrence of the endophytic diazotrophs Herbaspirillum spp. in roots, stems, and leaves, predominantly of Gramineae (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 197-200 
    Details
    ISSN: 1432-0789
    Keywords: Key words Herbaspirillum ; Endophytes of Gramineae ; Diazotrophs ; Survival in soil ; Nitrogen fixation ; Sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Since the first description of Herbaspirillum seropedicae in 1986, few data have been published on this diazotroph, possibly due to difficulties in isolating it from soil. In the present study we found that this bacterium seems to be an obligate endophyte which has been isolated from roots, stems, and leaves of a large number of samples of more than 10 different species of the Gramineae family, but only exceptionally from other plants. H. rubrisubalbicans, previously misnamed as “Pseudomonas” rubrisubalbicans, and known as a mild pathogen of sugarcane causing mottled stripe disease, confirms the endophytic habitat of this genus. This species occurs in roots, stems, and leaves of sugarcane and seems to be restricted to this crop. Inoculation of strains from both species into soil in high numbers resulted in a rapid decline in their numbers. In only 30 days the population of Herbaspirillum spp. in soil decreased below detection limits (〈100 cells g–1). When sorghum was planted in this soil, the bacteria reappeared and multiplied within the plant tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335935
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Endophytic establishment of Azorhizobium caulinodans through auxin-induced root tumors of rice (Oryza sativa L.) (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 293-302 
    Details
    ISSN: 1432-0789
    Keywords: Ammonium excretion ; Azorhizobium caulinodans ; Auxine 2.4-Dichlor-phenoxy-acetic acid ; Nitrogen fixation ; Paranodulation ; Rice ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice seedlings developed nodule-like tumors (para-nodules) along primary and secondary roots when treated with the auxin 2,4-dichlor-phenoxy-acetic acid (2,4-D). Histologically, these tumors appeared as cancerous out-grown lateral-root primordes and were thus comparable with stem nodules of the legume Sesbania rostrata. Azorhizobium caulinodans (a diazotroph known as a specific endophyte of Sesbania rostrata) was introduced and became established inside rice para-nodules and in root tissues around tumor bases. The infection with A. caulinodans followed a typical “crack-entry” invasion at places where paranodule tumors had emerged through the root cortex and epidermis. The bacteria settled with high cell densities in intercellular spaces of the induced tumors and between root cortical cells. Infection of plant cells took place both in the epidermis and in cortical tissue. Intracellularly established A. caulinodans was found inside the cytoplasm, surrounded by membrane-like structures. N2 fixation by tumor-inhabiting Azorhizobium sp. was increased at low O2 tensions (1.5–3 kPa) compared with an untreated control. Only a little activity remained at O2 tensions of 5 kPa and above. The present results confirm that root-tumor induction offers a suitable method of establishing diazotrophs endophytically in the roots of gramineous crops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334906
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Tree fallows: A comparison between five tropical tree species (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 50-56 
    Details
    ISSN: 1432-0789
    Keywords: Key words Agroforestry ; 15N ; Nitrogen fixation ; Phenolics ; 13C ; Tree fallows
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The natural abundance of 15N and 13C, conventional soil analyses, and biomass production by maize were used to study the influence of five tropical tree species on soils and their fertility. The experiment was conducted in Morogoro, Tanzania, to compare Cassia (Senna) siamea, Eucalyptus camaldulensis, E. tereticornis (all non-N2-fixing), Leucaena leucocephala, Prosopis chilensis (both N2-fixing), and a grass fallow. Maize biomass production, which was correlated with N uptake (P=0.001), was higher on soils from plots with 5-year-old Leucaena and Prosopis spp. compared to the grass fallow, while other tree species had less favourable effects on maize growth. The per cent N was higher in soil and δ15N of soil total N was lower under Prosopis sp. compared to soil under other tree species, which suggests an input from N2 fixation by Prosopis sp. A transfer of fixed N to maize or to understorey grass species was, however, not indicated by the 15N natural abundance. Prosopis sp. contributed more C to the soil than the other four tree species; the difference in δ13C between soils from Prosopis sp. plots and from grass fallow plots showed that the tree contributed 11% to the total C of the soil over a period of 8 years. The leaves of the N2-fixing species had a low ratio of lignin+phenols to N, and maize growth was negatively correlated with this parameter. The Eucalyptus spp. had leaves with a high lignin+phenols to N ratio, contributed very little C to the soil, and lowered the soil pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335818
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01867279
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422542
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Hydrogen uptake deficient mutants of Rhodopseudomonas capsulata (1983)
    Springer
    Archives of microbiology 136 (1983), S. 20-25 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00415604
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Effect of oxygen concentration on dark nitrogen fixation and respiration in cyanobacteria (1983)
    Springer
    Archives of microbiology 135 (1983), S. 287-292 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00413483
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425402
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    The occurrence of coryneform bacteria in the leaf cavity of Azolla (1980)
    Springer
    Archives of microbiology 127 (1980), S. 163-165 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428020
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422316
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    The uptake and hydrolysis of disaccharides by fast-and slow-growing species of Rhizobium (1981)
    Springer
    Archives of microbiology 129 (1981), S. 238-239 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425257
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Regulation of nitrogenase messenger RNA synthesis and stability in Klebsiella pneumoniae (1981)
    Springer
    Archives of microbiology 130 (1981), S. 38-43 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00527069
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Organisation of nodulation and nitrogen fixation genes on a Rhizobium trifolii symbiotic plasmid (1984)
    Springer
    Archives of microbiology 139 (1984), S. 151-157 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401991
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407946
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    RNA polymerase from Rhizobium japonicum (1983)
    Springer
    Archives of microbiology 135 (1983), S. 103-109 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408017
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Nitrogen metabolism in Xanthobacter H4-14 (1983)
    Springer
    Archives of microbiology 136 (1983), S. 219-221 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409848
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    The potential for diazotrophy in iron- and sulfur-oxidizing acidophilic bacteria (1995)
    Springer
    Archives of microbiology 164 (1995), S. 294-300 
    Details
    ISSN: 1432-072X
    Keywords: Key words Acetylene reduction ; Nitrogen fixation ; Leptospirillum ferrooxidans ; Thiobacillus ferrooxidans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acetylene reduction was observed with ferrous-iron-oxidizing Thiobacillus ferrooxidans, as expected from previous studies with this bacterium. Acetylene reduction was also found during the growth of T. ferrooxidans on tetrathionate. Only Leptospirillum ferrooxidans, one of several other phylogenetically diverse, ferrous-iron- and/or sulfur-oxidizing acidophilic microorganisms, also reduced acetylene. A reduction of the oxygen concentration in the culture atmosphere was necessary to alleviate inhibition of nitrogenase activity. DNA sequences homologous to nif structural genes were found in both organisms. Diazotrophic growth of L. ferrooxidans was inferred from an increase in iron oxidation in ammonium-free medium when the oxygen concentration was limited and from apparent inhibition by acetylene under these conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050267
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    GroEL chaperonins are required for the formation of a functional nitrogenase in Bradyrhizobium japonicum (1999)
    Springer
    Archives of microbiology 171 (1999), S. 279-289 
    Details
    ISSN: 1432-072X
    Keywords: Key words Cpn60 ; groESL ; Heat shock protein ; Hsp60 ; NifA ; Nitrogen fixation ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract At least five highly conserved, but disparately regulated groESL operons are present in Bradyrhizobium japonicum. Expression of groESL 3 is coregulated with symbiotic nitrogen fixation genes, implying a role of GroESL chaperonins in the nitrogen fixation process. Null mutants of individual groEL genes, however, were not impaired in symbiotic nitrogen fixation activity. By contrast, the groEL 3-plus-groEL 4 double mutant strain D4, which is mutated in those groEL genes that contribute most to the GroEL pool under symbiotic conditions, exhibited less than 5% Fix activity as compared to the wild-type. Expression of lacZ fusions made to several representative nif and fix genes was not, or only marginally, reduced in mutant D4, indicating that the requirement of chaperonins for nitrogen fixation does not occur at the level of RegSR-NifA-σ54- or FixLJ-FixK2-dependent gene regulation. Instead, immunoblot analyses revealed that the level of NifH and NifDK nitrogenase proteins was drastically decreased in extracts prepared from D4 bacteroids and from free-living cells grown anaerobically. Transcriptional fusions of the anaerobically induced groESL 3 promoter (P3) to all five B. japonicum groESL operons and also to groESL from Escherichia coli were integrated into the chromosome of mutant D4. Strains harboring P3 fused to groESL 1, groESL 2, groESL 5, or E. coli groESL partially complemented the symbiotic defect of mutant D4, whereas the wild-type phenotype was completely restored in strains complemented with P3 fused to groESL 3 (control) or groESL 4. Likewise, the growth defect of an E. coli groEL mutant could be corrected at least partially by individual B. japonicum groESL operons. In conclusion, both series of complementation analyses were not indicative of a strict substrate specificity of any of the B. japonicum groESL gene products, which is in good agreement with their high degree of sequence conservation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050711
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Nitrogen fixation associated with a hotspring green alga (1980)
    Springer
    Archives of microbiology 124 (1980), S. 161-167 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427722
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428014
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Mutants of Rhizobium japonicum defective in nodulation (1982)
    Springer
    Archives of microbiology 132 (1982), S. 219-224 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407954
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Nitrogen fixation and nitrate utilization by marine and freshwater Beggiatoa (1982)
    Springer
    Archives of microbiology 133 (1982), S. 172-177 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414997
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    The role of formate metabolism in nitrogen fixation in Rhizobium Spp. (1982)
    Springer
    Archives of microbiology 133 (1982), S. 312-317 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00521297
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429400
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429410
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00404777
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Denitrification by Azospirillum brasilense Sp 7 (1984)
    Springer
    Archives of microbiology 138 (1984), S. 212-216 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402122
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Transformations of inorganic nitrogen by Azospirillum spp. (1981)
    Springer
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411058
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Glutathione reductase activity in heterocysts and vegetative cells of the cyanobacterium Nostoc muscorum (1984)
    Springer
    Archives of microbiology 140 (1984), S. 215-217 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454930
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Interaction of respiratory and photosynthetic electron transport in Anabaena variabilis Kütz. (1982)
    Springer
    Archives of microbiology 132 (1982), S. 333-337 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00413385
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Nitrogen metabolism inRhodopseudomonas globiformis (1982)
    Springer
    Archives of microbiology 133 (1982), S. 6-10 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00943761
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408014
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Bradyrhizobium japonicum possesses two discrete sets of electron transfer flavoprotein genes:fixA, fixB andetfS, etfL (1996)
    Springer
    Archives of microbiology 165 (1996), S. 169-178 
    Details
    ISSN: 1432-072X
    Keywords: Bradyrhizobium japonicum ; Electron transfer flavoprotein ; etf Genes ; fix Genes ; Nitrogen fixation ; Phylogenetic tree ; Protein family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A group of four co-regulated genes (fixA, fixB, fixC, fixX) essential for symbiotic nitrogen fixation has been described in several rhizobial species, includingBradyrhizobium japonicum. The complete nucleotide sequence of theB. japonicum fixA, fixB andfixC, genes is reported here. The derived amino acid sequences confirmed the previously noted sequence similarity between FixA and the β-subunit and between FixB and the α-subunit of mammalian andParacoccus denitrificans electron transfer flavoproteins (ETF). Since the classical role of ETF is in β-oxidation of fatty acids, a process unrelated to nitrogen fixation, we rationalized thatB. japonicum ought to contain bona fideetf genes in addition to theetf-like genesfixA andfixB. Therefore, we identified, cloned, sequenced, and transcriptionally analyzed theB. japonicum etfSL genes encoding the β-and α-subunits of ETF. TheetfSL genes, but not thefix genes, are transcribed in aerobically grown cells. An amino acid sequence comparison between all available ETFs and ETF-like proteins revealed the existence of two distinguishable subfamilies. Group I comprises housekeeping ETFs that link acyl-CoA dehydrogenase reactions with the respiratory chain, such as in the fatty acid degradation pathway.B. japonicum EtfS and EtfL clearly belong to this group. Group II contains ETF-like proteins that are synthesized only under certain specific growth conditions and receive electrons from the oxidation of specific substrates. The products of the anaerobically inducedfixA andfixB genes ofB. japonicum are members of that group.B. japonicum is the first example of an organism in which genes for proteins of both groups I and II of the ETF family have been identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01692858
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Control of nitrogen fixation by oxygen in purple nonsulfur bacteria (1996)
    Springer
    Archives of microbiology 165 (1996), S. 219-225 
    Details
    ISSN: 1432-072X
    Keywords: Key words Phototrophic bacteria ; Rhodobacter capsulatus ; Rhodospirillum rubrum ; Nitrogenase ; Nitrogen fixation ; Control of nif gene transcription ; Control of nitrogenase activity ; Control of nitrogenase formation ; Oxygen control ; Continuous culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some members of the facultatively phototrophic bacteria are able to grow diazotrophically in the presence of oxygen. As in other diazotrophs, the nitrogenase of the phototrophic bacteria is highly sensitive to oxygen; therefore, both the function and the expression of nitrogenase are strictly controlled by oxygen. This review focuses on the different levels of oxygen control in the two most extensively studied facultatively phototrophic bacteria, Rhodospirillum rubrum and Rhodobacter capsulatus. Current data show that oxygen controls nitrogen fixation at least at the levels of (1) transcription of nif genes, (2) the accumulation of the three different nitrogenase polypeptides, (3) the cellular activity of nitrogen fixation. In Rba. capsulatus, activation of the nifH promoter is the least oxygen-sensitive step, and nitrogen fixation is the most oxygen-sensitive step. ADP-Ribosylation of nitrogenase, occurring under conditions of ammonium-dependent inactivation of the enzyme, is not observed when Rba. capsulatus is exposed either suddenly or at a steady state to increased oxygen concentrations. Future research is required to understand the mechanisms of protection of nitrogenase against oxygen damage, and also the mechanisms by which oxygen controls the formation and activity of nitrogenase; this will add significantly to the biologically important question of how cells deal with the presence of toxic oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050319
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    The [2Fe-2S] protein I (Shetna protein I) from Azotobacter vinelandii is homologous to the [2Fe-2S] ferredoxin from Clostridium pasteurianum (1999)
    Springer
    JBIC 4 (1999), S. 311-317 
    Details
    ISSN: 1432-1327
    Keywords: Key words Iron-sulfur ; Nitrogen fixation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The [2Fe-2S] protein from Azotobacter vinelandii that was previously known as iron-sulfur protein I, or Shethna protein I, has been shown to be encoded by a gene belonging to the major nif gene cluster. Overexpression of this gene in Escherichia coli yielded a dimeric protein of which each subunit comprises 106 residues and contains one [2Fe-2S] cluster. The sequence of this protein is very similar to that of the [2Fe-2S] ferredoxin from Clostridium pasteurianum (2FeCpFd), and the four cysteine ligands of the [2Fe-2S] cluster occur in the same positions. The A. vinelandii protein differs from the C. pasteurianum one by the absence of the N-terminal methionine, the presence of a five-residue C-terminal extension, and a lesser number of acidic and polar residues. The UV-visible absorption and EPR spectra, as well as the redox potentials of the two proteins, are nearly identical. These data show that the A. vinelandii FeS protein I, which is therefore proposed to be designated 2FeAvFdI, is the counterpart of the [2Fe-2S] ferredoxin from C. pasteurianum. The occurrence of the 2FeAvFdI-encoding gene in the nif gene cluster, together with the previous demonstration of a specific interaction between the 2FeCpFd and the nitrogenase MoFe protein, suggest that both proteins might be involved in nitrogen fixation, with possibly similar roles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050317
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    On the reduced and oxidized forms of the FeMo- cofactor of Azotobacter vinelandii nitrogenase (1997)
    Springer
    Theoretical chemistry accounts 96 (1997), S. 141-145 
    Details
    ISSN: 1432-2234
    Keywords: Key words: Nitrogenase ; Nitrogen fixation ; FeMo enzymes ; Oxidation reduction of FeMo cofactor ; INDO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract. Reduced and oxidized forms of the FeMo- cofactor of Azotobacter vinelandii nitrogenase are examined theoretically within the intermediate neglect of differential overlap model. The results obtained favor one of the experimentally suggested modes of contraction of the metal system which results in an expansion of the central cavity of the cofactor. The bond index analysis indicates marked changes in the Mo coordination upon electron addition which may contribute to an opening of the Mo atom as a possible binding site at the advanced stages of the reduction process. In this work we also compare the 39- and 41-electron [MoFe7] core as possible native resting states, both compatible with known spin and Mössbauer spectroscopies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002140050215
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    The interaction of nitrogen and carbon monoxide with certain ions and neutral species (1982)
    Springer
    Theoretical chemistry accounts 60 (1982), S. 579-587 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549613
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Long-term effects of metals in sewage sludge on soils, microorganisms and plants (1995)
    Springer
    Journal of industrial microbiology and biotechnology 14 (1995), S. 94-104 
    Details
    ISSN: 1476-5535
    Keywords: Metal toxicity ; Rhizobia ; Soil microbial biomass ; Mycorrhiza ; Cyanobacteria ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary This paper reviews the evidence for impacts of metals on the growth of selected plants and on the effects of metals on soil microbial activity and soil fertility in the long-term. Less is known about adverse long-term effects of metals on soil microorganisms than on crop yields and metal uptake. This is not surprising, since the effects of metals added to soils in sewage sludge are difficult to assess, and few long-term experiments exist. Controlled field experiments with sewage sludges exist in the UK, Sweden, Germany and the USA and the data presented here are from these long-term field experiments only. Microbial activity and populations of cyanobacteria,Rhizobium leguminosarum bv.trifolii, mycorrhizae and the total microbial biomass have been adversely affected by metal concentrations which, in some cases, are below the European Community's maximum allowable concentration limits for metals in sludge-treated soils. For example, N2-fixation by free living heterotrophic bacteria was found to be inhibited at soil metal concentrations of (mg kg−1): 127 Zn, 37 Cu, 21 Ni, 3.4 Cd, 52 Cr and 71 Pb. N2-fixation by free-living cyanobacteria was reduced by 50% at metal concentrations of (mg kg−1): 114 Zn, 33 Cu, 17 Ni, 2.9 Cd, 80 Cr and 40 Pb.Rhizobium leguminosarum bv.trifolii numbers decreased by several orders of magnitude at soil metal concentrations of (mg kg−1): 130–200 Zn, 27–48 Cu, 11–15 Ni, and 0.8–1.0 Cd. Soil texture and pH were found to influence the concentrations at which toxicity occurred to both microorganisms and plants. Higher pH, and increased contents of clay and organic carbon reduced metal toxicity considerably. The evidence suggests that adverse effects on soil microbial parameters were generally found at surpringly modest concentrations of metals in soils. It is concluded that prevention of adverse effects on soil microbial processes and ultimately soil fertility, should be a factor which influences soil protection legislation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569890
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Possible role of a short extra loop of the long-chain flavodoxin from Azotobacter chroococcum in electron transfer to nitrogenase: Complete 1H, 15N and 13C backbone assignments and secondary solution structure of the flavodoxin (1996)
    Springer
    Journal of biomolecular NMR 7 (1996), S. 315-330 
    Details
    ISSN: 1573-5001
    Keywords: Triple-resonance 3D NMR ; Resonance assignments ; Chemical shifts ; Protein secondary structure ; Electron transfer ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The 1H, 15N and 13C backbone and 1H and 13C beta resonance assignments of the long-chain flavodoxin from Azotobacter chroococcum (the 20-kDa nifF product, flavodoxin-2) in its oxidized form were made at pH 6.5 and 30°C using heteronuclear multidimensional NMR spectroscopy. Analysis of the NOE connectivities, together with amide exchange rates, 3JHnHα coupling constants and secondary chemical shifts, provided extensive solution secondary structure information. The secondary structure consists of a five-stranded parallel β-sheet and five α-helices. One of the outer regions of the β-sheet shows no regular extended conformation, whereas the outer strand β4/6 is interrupted by a loop, which is typically observed in long-chain flavodoxins. Two of the five α-helices are nonregular at the N-terminus of the helix. Loop regions close to the FMN are identified. Negatively charged amino acid residues are found to be mainly clustered around the FMN, whereas a cluster of positively charged residues is located in one of the α-helices. Titration of the flavodoxin with the Fe protein of the A. chroococcum nitrogenase enzyme complex revealed that residues Asn11, Ser68 and Asn72 are involved in complex formation between the flavodoxin and Fe protein. The interaction between the flavodoxin and the Fe protein is influenced by MgADP and is of electrostatic nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00200433
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Nitrogen nutrition and the development and senescence of nodules on cowpea seedlings (1984)
    Springer
    Planta 162 (1984), S. 316-326 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396743
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Appearance of a novel form of plant glutamine synthetase during nodule development in Phaseolus vulgaris L. (1983)
    Springer
    Planta 157 (1983), S. 254-258 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00405190
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Localization of H+-ATPases in soybean root nodules (1999)
    Springer
    Planta 209 (1999), S. 25-32 
    Details
    ISSN: 1432-2048
    Keywords: Key words: ATPase ; Glycine max ; Nitrogen fixation ; Symbiosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The localization of H+-ATPases in soybean (Glycine max L. cv. Stevens) nodules was investigated using antibodies against both P-type and V-type enzymes. Immunoblots of peribacteroid membrane (PBM) proteins using antibodies against tobacco and Arabidopsis H+-ATPases detected a single immunoreactive band at approximately 100 kDa. These antibodies recognized a protein of similar relative molecular mass in the crude microsomal fraction from soybean nodules and uninoculated roots. The amount of this protein was greater in PBM from mature nodules than in younger nodules. Immunolocalization of P-type ATPases using silver enhancement of colloidal-gold labelling at the light-microscopy level showed signal distributed around the periphery of non-infected cells in both the nodule cortex and nodule parenchyma. In the central nitrogen-fixing zone of the nodule, staining was present in both the infected and uninfected cells. Examination of nodule sections using confocal microscopy and fluorescence staining showed an immunofluorescent signal clearly visible around the periphery of individual symbiosomes which appeared as vesicles distributed throughout the infected cells of the central zone. Electron-microscopic examination of immunogold-labelled sections shows that P-type ATPase antigens were present on the PBM of both newly formed, single-bacteroid symbiosomes just released from infection threads, and on the PBM of mature symbiosomes containing two to four bacteroids. Immunogold labelling using antibody against the B-subunit of V-type ATPase from oat failed to detect this protein on symbiosome membranes. Only a very faint signal with this antibody was detected on Western blots of purified PBM. During nodule development, fusion of small symbiosomes to form larger ones containing multiple bacteroids was observed. Fusion was preceded by the formation of cone-like extensions of the PBM, allowing the membrane to make contact with the adjoining membrane of another symbiosome. We conclude that the major H+-ATPase on the PBM of soybean is a P-type enzyme with homology to other such enzymes in plants. In vivo, this enzyme is likely to play a critical role in the regulation of nutrient exchange between legume and bacteroids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050603
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Ferrous iron is transported across the peribacteroid membrane of soybean nodules (1998)
    Springer
    Planta 207 (1998), S. 83-87 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Ferrous iron uptake ; Glycine (iron uptake) ; Nitrogen fixation ; Peribacteroid membrane ; Root nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Symbiosomes and bacteroids isolated from soybean (Glycine max Merr.) nodules are able to take up ferrous iron. This uptake activity was completely abolished in the presence of ferrous-iron chelators. The kinetics of uptake were characterized by initially high rates of iron internalization, but no saturation was observed with increasing iron concentration. This process does not appear to involve the ferric reductase of the peribacteroid membrane. The transport of ferrous iron was inhibited by other transition metals, particularly copper. Ferrous iron was taken up by symbiosomes more efficiently than the ferric form. This indicates that the iron transport from the plant host cell to the microsymbiont in vivo may occur mainly as the ferrous form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050458
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Regulation of nif gene expression in Enterobacter agglomerans: nucleotide sequence of the nifLA operon and influence of temperature and ammonium on its transcription (1995)
    Springer
    Molecular genetics and genomics 249 (1995), S. 629-636 
    Details
    ISSN: 1617-4623
    Keywords: Nitrogen fixation ; nifM ; nifL ; nifA ; nifB
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nucleotide sequence of a plasmid-borne 3.9 kb XhoI-SmaI fragment comprising the 3′-region of the nifM gene, the nifL and nifA genes and the 5′-region of nifB gene of Enterobacter agglomerans was determined. The genes were identified by their homology to the corresponding nif genes of Klebsiella pneumoniae. A typical σ54-dependent promoter and a consensus NtrC-binding motif were identified upstream of nifL. The predicted amino acid sequence of NifL showed close similarities to NifL of K. pneumoniae and Azotobacter vinelandii. However, no histidine residue was found to correspond to histidine-304 of A. vinelandii NifL, which had been proposed to be required for the repressor activity of NifL. The NifA sequence with a putative DNA binding motif (Q(X3) A (X3) G (X5)I) and an ATP binding site in the C-terminal and central domains, respectively, resembles that of other known NifA proteins. The function of the nifL and nifA genes was demonstrated in vivo using a binary plasmid system by their ability to activate a nifH promoter-lacZ fusion at different temperatures and concentrations of NH 4 + . Maximal promoter activity occurred at 25°C, and it appears that the sensitivity of NifA to elevated temperatures is independent of NifL. The expression of nifL inhibited promoter activity in the presence of NifA when the initial NH 4 + concentration in the medium exceeded 4 mM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418032
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Map order and linkage distances of molecular markers close to the supernodulation (nts-1) locus of soybean (1997)
    Springer
    Molecular genetics and genomics 254 (1997), S. 29-36 
    Details
    ISSN: 1617-4623
    Keywords: Key words Symbiosis ; RFLP mapping ; Nitrogen fixation ; Bulked segregant analysis ; Nodulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The molecular characteristics of markers in the chromosome region surrounding the supernodulation gene (nts-1) of soybean (Glycine max L. Merr.) were investigated in 187 F2 plants from a cross of G. max cv. Bragg (nts) and G. soja PI468.397 (wild-type nodulation). RFLP marker pUTG-132a, linked tightly (0.7±0.5 cM) to nts-1, was converted to a PCR marker. The polymorphism resides within a 1.72 kb PstI fragment and consists of an 832 bp insertion in G. max relative to the wild progenitor G. soja. The insertion is flanked by a 35 bp direct duplication that was found only once in G. soja. Data suggest that the pUTG-132a sequence exists only once in the genome, which is compatible with the recessive nature of nts-1. Accordingly, pUTG-132a is a valuable marker for map-based cloning. Another RFLP marker, pA-381, was mapped 4.8 cM distal to nts-1. Marker order, established by Maximum Likelihood Analysis, placed nts-1 between pUTG-132a and pA-381. To generate additional molecular markers, a segregating F2 population was analysed using bulked segregant analysis (BSA) and single oligonucleotide primer-based PCR (DNA amplification fingerprinting; DAF). PCR marker pcr5-4L was mapped to soybean linkage group H and sequenced. The data revealed (i) recombination events and marker order in the nts-1 region; (ii) the molecular nature and cause of polymorphisms in linked molecular markers; (iii) a low density of polymorphisms around nts-1, and (iv) diploidy of the distal region of linkage group H of soybean.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050387
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    The Rhizobium etli FixL protein differs in structure from other known FixL proteins (1998)
    Springer
    Molecular genetics and genomics 257 (1998), S. 576-580 
    Details
    ISSN: 1617-4623
    Keywords: Key wordsRhizobium ; Nitrogen fixation ; Two-component systems ; FixL ; Heme protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The central heme-binding domain in the FixL proteins of Sinorhizobium meliloti, Bradyrhizobium japonicum, Rhizobium leguminosarum biovar viciae and Azorhizobium caulinodans, is highly conserved. The similarity with the corresponding domain in the Rhizobium etli FixL protein is considerably less. This observation prompted us to analyze the heme-binding capacities of the R. etli FixL protein. The R. etlifixL gene was overexpressed in Escherichia coli. In the presence of S. meliloti FixJ, the overexpressed R. etli FixL protein was able to enhance FixJ-mediated activation of an S. meliloti pnifA-lacZ fusion, indicating that the R.␣etli FixL protein possesses an active conformation in E. coli. Subsequently, using a non-denaturing gel assay for heme, we analyzed the heme-binding capacity of the R.␣etli FixL protein expressed in E. coli, taking the S.␣meliloti FixL protein as a positive control. The R. etli FixL protein expressed in E. coli does not contain a heme group, in contrast to the S. meliloti FixL protein. Therefore we conclude that the R. etli FixL is a non-heme protein in the nif regulatory cascade.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050684
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Structural and functional analysis of the fixLJ genes of Rhizobium leguminosarum biovar phaseoli CNPAF512 (1995)
    Springer
    Molecular genetics and genomics 249 (1995), S. 117-126 
    Details
    ISSN: 1617-4623
    Keywords: Rhizobium leguminosarum biovar phaseoli ; fixLJ genes ; Two-component systems ; Nitrogen fixation ; Gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fixLJ genes of Rhizobium leguminosarum biovar phaseoli CNPAF512 were identified by DNA hybridization of a genomic library with an internal fragment of the Rhizobium meliloti fixJ gene. The nucleotide sequence was determined and the corresponding amino acid sequence was aligned with the amino acid sequences of the FixL proteins of R. meliloti, Bradyrhizobium japonicum and Azorhizobium caulinodans. While the FixJ protein and the carboxy-terminal part of the FixL protein are highly homologous to the other FixL and FixJ proteins, the homology in the central heme-binding, oxygen-sensing domain and in the amino-terminal domain of FixL is very low. The R. leguminosarum bv. phaseoli FixL protein does not contain the heme-binding motif defined for the previously described FixL proteins. R. leguminosarum bv. phaseoli fixLJ and fixJ mutants were constructed. These mutants can still fix nitrogen, albeit at a reduced level. Expression analysis of nifA-gusA and nifH-gusA fusions in the constructed mutants revealed that the R. leguminosarum bv. phaseoli fixLJ genes are involved in microaerobic nifH expression but not in nifA expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290243
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Delivery of N2 to bacteroids in simulated soybean nodule cells: consideration of gradients of concentration of dissolved N2 in cell walls, cytoplasm, and symbiosomes (1999)
    Springer
    Protoplasma 206 (1999), S. 137-142 
    Details
    ISSN: 1615-6102
    Keywords: Diffusion ; Intercellular spaces ; Nitrogen ; Nitrogen fixation ; Oxygen ; Symbiosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The previously published simulation of physiological functions occurring in infected cells of soybean nodules has been extended to include consideration of the diffusion of N2 from the outside of a nodule to the nitrogen-fixing bacteroids, in relation to published values for the apparentK m(N2) for nitrogen fixation in the soybean nodule system. Nitrogen fixation is driven by bacteroid respiration, so increases in the average relative oxygenation (Y) of cytoplasmic leghaemoglobin lead to increased bacteroid respiration, increased nitrogen fixation, and greater differences in concentration of dissolved N2 between the cell surface and the innermost bacteroids (d[N2]). Over the range ofY considered, values for d[N2] were from 5.2- to 6.2-fold greater than the corresponding values for d[O2], because of facilitation of O2 flux by cytoplasmic leghaemoglobin. Gradients of [N2] within symbiosomes are small relative to cytoplasmic values and at the symbiosome surface [N2] was greater than 0.4 mol/m3 at the greatest rates of nitrogen fixation calculated. Therefore, it is unlikely that values for [N2] anywhere in the infected cell are low enough to affect rates of nitrogen fixation significantly, unless low external atmospheric N2 pressures are used experimentally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279260
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Delivery of O2 to bacteroids in soybean nodule cells: Consideration of gradients of concentration of free, dissolved O2 in and near symbiosomes and beneath intercellular spaces (1996)
    Springer
    Protoplasma 191 (1996), S. 9-20 
    Details
    ISSN: 1615-6102
    Keywords: Diffusion ; Intercellular spaces ; Mitochondria ; Symbiosomes ; Nitrogen fixation ; Oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Based on a simulation model of the structure of and distribution of O2 within infected cells of soybean nodules, gradients of concentration of dissolved O2 ([O2]) have been calculated within and between symbiosomes embedded in host cytoplasm, through which the flux of O2 to the symbiosomes is facilitated by leghaemoglobin. As a consequence of facilitation, gradients of [O2] in cytoplasm between symbiosomes are very small. Within symbiosomes, from which leghaemoglobin is considered to be absent, respiration by bacteroids generates steeper gradients of [O2], thus restricting respiration and N2 fixation. However, if bacteroid mass is considered to be randomly distributed within a symbiosome, about 80% of this mass lies within about 0.6 μm of the surface (the peribacteroid membrane). Consequently, respiration within a symbiosome was calculated to be between 65% and 92% of that attained if bacteroids were directly in contact with the cytoplasm. For N2 fixation, the corresponding values were 44% to 91%. In cytoplasm, near the surface of a symbiosome, there is a boundary layer in which equilibrium between O2, leghaemoglobin and oxyleghaemoglobin is perturbed by O2 consumption within. Calculations of the thickness of the boundary layers gave values of only 3.65 to 3.75×10−9 m, thus they had little effect on calculated gradients of [O2] in cytoplasm. In contrast, perturbations of the leghaemoglobin oxygenation equilibrium affected layers of cytoplasm beneath intercellular spaces to a depth of 0.15 to 0.3×10−6 m in the physiological range of volume average [O2]. This affected gradients of [O2] in the cytoplasm near intercellular spaces. Revisions have been made to the model cell, incorporating these new calculations. Results suggest that infected nodule cells may be able to withstand 1–2 μM O2 in the outermost layers of cytoplasm without inhibition of N2 fixation caused by excessive O2 within the symbiosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280821
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Subcellular localization of glycoprotein epitopes during the development of lupin root nodules (1998)
    Springer
    Protoplasma 201 (1998), S. 71-84 
    Details
    ISSN: 1615-6102
    Keywords: Lupinus albus ; Nitrogen fixation ; Oxygen diffusion ; Glycoprotein ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The monoclonal antibodies MAC236 and MAC265, raised against a soluble component of pea nodules, were used to elucidate the presence and subcellular localization of glycoprotein epitopes during the development of lupin (Lupinus albus L. cv. Multolupa) nodules, by means of immunocytochemistry and Western blot analysis. These antibodies recognize a single band of 95 kDa in pea, soybean and bean nodules, whilst two different bands of 240 and 135 kDa cross-react with MAC236 and MAC265 respectively in lupin nodules. This fact may indicate that the recognized epitopes can be present in different subcellular compartments and/or play different roles through the development of functional nodules. The results show that MAC265 is mainly associated with Bradyrhizobium infection and with the development of nodule primordium, in the first stages of nodulation. MAC265 is also detected when glycoprotein transport takes place across the cytoplasm and the cell wall, and also in the intercellular spaces of the middle cortex, attached to cell walls. The amount of MAC265 remains constant through nodule development. In contrast the amount of MAC236 increases with nodule age, parallel to the establishment of nitrogenase activity. This antibody is localized in cytoplasmic globules attached to the inner side of cell walls in the middle cortex, and mainly in the matrix filling the intercellular spaces of the middle and inner cortex. This main site of localization of MAC236 may indicate a role in the functioning of the oxygen diffusion barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280713
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Quantitative viability of seaweed tissues assessed with 2,3,5-triphenyltetrazolium chloride (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 31-36 
    Details
    ISSN: 1573-5176
    Keywords: Porphyra ; seaweed ; spectrophotometer ; triphenyltetrazolium ; viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A spectrophotometric quantification method was optimized to evaluate its utility in seaweed tissue viability tests using the enzymatic reduction of colorless 2,3,5-triphenyltetrazolium chloride (TTC) to a colored triphenylformazan (TPF). To allow accurate determination of TPF in the seaweed Porphyra thallus and conchocelis, 0.2 g of tissues are incubated with 4 mL of 0.8% TTC reagent in the dark at 20°C for 1 h under a mineral oil layer. The TPF formed in tissues was extracted for 15 min at 60°C with 2 mL of 0.2 N KOH in 25% ethanol. Then TPF is partitioned away by prompt addition of hexane and vortexing. By this procedure, we have observed nearly complete separation of TPF, and observed good spectrophotometric discrimination between TPF and other hexane-soluble pigments at 545 nm. This procedure has proved applicable to a wide range of seaweed taxa; 1 species of Chlorophyta, 4 species of Phaeophyta and 7 species of Rhodophyta tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008059314639
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Factors influencing seaweed responses to eutrophication: some results from EU-project EUMAC (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 69-78 
    Details
    ISSN: 1573-5176
    Keywords: seaweed ; algal blooms ; eutrophication ; general mechanisms ; management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seaweed responses to eutrophication and their role in coastal eutrophication processes were compared at 8 different sites along the European coasts from the Baltic to the Mediterranean as part of the EU-ENVIRONMENT Project Marine Eutrophication and benthic Macrophytes (EUMAC). Structural and functional changes of marine benthic vegetation typical of eutrophic waters, in particular mass development (blooms) of certain seaweeds, are not merely the result of increased nutrient loading, but must be attributed to complex interactions of primary and secondary effects during the eutrophication process. Due to species-specific physiological properties of the algae (nutrient kinetics, growth potential, light, temperature requirements), the combined effects of abiotic and biotic factors on juvenile or adult developmental stages control the development of algal blooms in different ways. In particular the role of light, temperature, water motion and oxygen depletion, as well as of grazers, on early and adult developmental stages of the algae are considered. The result are discussed in the context of coastal eutrophication control and management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008076026792
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Anaerobic digestion of Ulva sp. 2. Study of Ulva degradation and methanisation of liquefaction juices (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 164-177 
    Details
    ISSN: 1573-5176
    Keywords: Ulva ; seaweed ; decomposition ; acidogenesis ; methanisation ; anaerobic digestion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract ‘Green tides’ Ulva is often harvested for environmental reasons, and put in a dump. Observations on degradation of Ulva in such dumps led us to consider recovery of hydrolysis juice in order to methanize this rather than the entire alga. The hydrolysis step was then studied in the laboratory and under real conditions. The decomposition of Ulva was rapid (7.1% C d−1), but its degradation incomplete (38% C remaining after 52 days). After 9 months in a dump, VFA contents in the flows were insignificant and N and C contents in the remaining material were due to the non-degradable fraction. Modifications of the physical or chemical conditions of hydrolysis didn't improve suffisently significantly the results to be used on a large scale. On the other hand, the techniques which could allow a rapid recovery of the juice improved together the recovery of the COD. The hydrolysis juice is a very good substrate for methanisation: the methane yield reached 330 L kg−1 VS, and the epuration rate 93%. The process combining the two steps, hydrolysis and juice methanisation, is one which offers a reasonable compromise between methane output, productivity of the system and treatment cost. However, there are still two problems, dependence on climatic conditions, and too low a recovery rate of the initial organic material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008028127701
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Aerobic microbial degradation of alginate in Laminaria hyperborea stipes containing different levels of polyphenols (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 45-54 
    Details
    ISSN: 1573-5176
    Keywords: seaweed ; aerobic ; degradation ; Laminaria hyperborea ; alginate ; lyase ; polyphenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polyphenols present in brown seaweed tissue may seriously affect aerobic microbial degradation, particularly the alginate present. Laminaria hyperborea stipes, harvested at 59 °N off the Norwegian coast in autumn, were degraded at different levels of polyphenols in aerated batch reactors at 35 °C and pH 7. This was achieved by manipulating the relative amounts of peripheral tissue, by removing or adding the mechanically peeled outer phenolic layer, using standardized inocula already adapted to L. hyperborea degradation. The degradation of organic matter was clearly depressed by increasing the amount of peripheral tissue. Alginate lyase activity was also negatively correlated to the amount of peripheral tissue loaded, presumably due to the release of reactive polyphenols. The total digestion rates of alginate were reduced by more than a factor of two at enhanced amounts of peripheral tissue. The guluronic content of extracted Na-alginate increased during the degradation, despite the presence of significant amounts of guluronate specific alginate lyase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007956230761
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Ammonium and nitrate uptake by Laminaria saccharina and Nereocystis luetkeana originating from a salmon sea cage farm (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 333-340 
    Details
    ISSN: 1573-5176
    Keywords: nitrogen uptake ; C/N ratio ; kelp ; seaweed ; Laminaria saccharina ; Nereocystis luetkeana ; environmental effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the laboratory, ammonium and nitrate uptakes were measured for juvenile Laminaria saccharina (L.) Lamour. and Nereocystis luetkeana (Mert.) Post. et Rupr. originating from a salmon sea cage farm in northwestern British Columbia, Canada. The effect of various concentrations of NH4+ and NO3-, which are typical of salmon farming environments, on uptakes values were examined. Both L. saccharina and Nereocystis revealed simultaneous uptake of NH4+ and NO3- when both NH4+ and NO3- were present in the medium. During a 3-h incubation, mean uptake rates of NH4+ and NO3- by L. saccharina ranged from 6.0–8.9 and 4.6–10.6 μmol gdw-1 h-1, respectively, and by Nereocystis, they ranged from 6.6–9.3 μmol gdw-1 h-1 and 6.1–17.0 μmol gdw-1 h-1, respectively. The highest uptake rates (14.8 μmol NH4+ gdw-1 h-1by L. saccharina and 27.2 μmol NO3- gdw-1 h-1 by Nereocystis) occurred at the highest concentration (40 μM NH4+ plus 30 μM NO3-) during a 1 h incubation. Nitrate uptake by both L. saccharina and Nereocystis increased linearly up to the highest nitrate level tested (30 μM), whereas uptake rates of ammonium were stable beyond 10 μM NH4+ to reach approximately 10 and 13 μmol gdw-1 h-1, respectively, for L. saccharina and Nereocystis. Unlike L. saccharina, Nereocystis showed a significant preference for NO3- when more than 20 μM NO3- was present in the medium ( p 〈0.05). Both L. saccharina and Nereocystis would be suitable for integrated cultivation of salmon/kelp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008092521651
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Regeneration and reproduction of Mazzaella cornucopiae (Rhodophyta, Gigartinaceae) after frond harvesting (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 531-537 
    Details
    ISSN: 1573-5176
    Keywords: Gigartinaceae ; harvesting ; Mazzaella ; regeneration ; reproduction ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects that different intensities of frond harvesting have on frond regeneration and subsequent production of reproductive structures were investigated for the red intertidal alga Mazzaella cornucopiae (Postels & Ruprecht) Hommersand from British Columbia, Canada. Harvesting was done by pruning fronds in the late spring (when stand biomass is highest) of 1993 at two intensities: total and partial collection of fronds, in this second case leaving all frond biomass less than 1 cm high in place. Holdfasts were not damaged. Total percent cover of thalli, frond density, mean frond length, and stand biomass for these experimental quadrats were statistically similar to values for control quadrats in the spring of 1994. These results suggest that one total harvest of fronds per year, done in late spring without damaging holdfasts, may give the highest sustainable yield of biomass. The effects of harvesting intensity on reproduction were variable and difficult to explain. Neither the appearance nor the abundance of cystocarpic fronds were affected by frond pruning, compared with control areas, but pruning did affect the appearance and the abundance of tetrasporic fronds. Partial pruning resulted in a longer presence of tetrasporic fronds, whereas total pruning was associated with their complete absence. Results are compared with those for the few other species of the Gigartinaceae for which experimental harvesting has been done.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008029632351
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Isolation and characterisation of a fourth hemagglutinin from the red alga, Gracilaria verrucosa, from Japan (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 49-56 
    Details
    ISSN: 1573-5176
    Keywords: hemagglutinins ; Gracilaria ; sulphated polysaccharide ; carbohydrate specificity ; seaweed ; electrophoretic behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolation and characterisation of marine algal hemagglutinins or lectins are essential for their potential industrial application as specific carbohydrate affinity ligands. The phosphate buffer extract of the red alga, Gracilaria verrucosa (Huds.) Papenfuss (Gigartinales, Rhodophyta) from Japan is known to contain three different hemagglutinins. The extract of the alga collected in March 1993 from Kagawa Prefecture, Japan, was purified by ammonium sulphate fractionation, ion exchange and gel filtration chromatography. Using gel filtration, two peaks were obtained (hereafter Peak 1 and Peak 2) which differed in molecular size and hemagglutinating activity against horse erythrocytes. Peak 1 corresponded to the known high molecular weight hemagglutinin, H-GVH. Peak 2 contained large amounts of hexose and sulphate along with a small amount of protein. It had a low molecular weight (gel filtration) similar to that of two of the previously reported G.verrucosa hemagglutinins but differed in its electrophoretic behaviour. Peak 2 is therefore a fourth hemagglutinin. Its activity was not inhibited by any of the monosaccharides tested but by the complex glycoproteins such as asialofetuin and fetuin. It had no divalent cation requirement for hemagglutination. The properties of this novel hemagglutinin could prove useful in industrial applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008011616001
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...