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  • Rat  (286)
  • Nitrogen fixation  (145)
  • Springer  (430)
  • Elsevier  (1)
  • 2015-2019  (1)
  • 2010-2014  (2)
  • 1985-1989  (428)
  • 1
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    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
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  • 2
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    The depth-distribution of nitrogen fixation by Trichodesmium spp. colonies in the tropical–subtropical North Atlantic (2015)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 104 (2015): 72-91, doi:10.1016/j.dsr.2015.06.012.
    Description: Nitrogen fixation is an important yet still incompletely constrained component of the marine nitrogen cycle, particularly in the subsurface. A Video Plankton Recorder (VPR) survey in the subtropical North Atlantic found higher than expected Trichodesmium colony abundances at depth, leading to the hypothesis that deep nitrogen fixation in the North Atlantic may have been previously underestimated. Here, Trichodesmium colony abundances and modeled nitrogen fixation from VPR transects completed on two cruises in the tropical and subtropical North Atlantic in fall 2010 and spring 2011 were used to evaluate that hypothesis. A bio-optical model was developed based on carbon-normalized nitrogen fixation rates measured on those cruises. Estimates of colony abundance and nitrogen fixation were similar in magnitude and vertical and geographical distribution to conventional estimates in a recently compiled climatology. Thus, in the mean, VPR-based estimates of volume-specific nitrogen fixation rates at depth in the tropical North Atlantic were not inconsistent with estimates derived from conventional sampling methods. Based on this analysis, if Trichodesmium nitrogen fixation by colonies is underestimated, it is unlikely that it is due to underestimation of deep abundances by conventional sampling methods.
    Description: We gratefully acknowledge support of this research by NSF and NASA. A NASA Earth and Space Science Fellowship supported E. Olson's graduate studies.
    Keywords: Nitrogen fixation ; Trichodesmium spp. ; North Atlantic ; Video Plankton Recorder
    Repository Name: Woods Hole Open Access Server
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  • 3
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    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
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  • 4
    Electronic Resource
    Electronic Resource
    Identification of brain tumours in rats using laser-induced fluorescence and haematoporphyrin derivative (1989)
    Springer
    Lasers in medical science 4 (1989), S. 241-249 
    Details
    ISSN: 1435-604X
    Keywords: Brain tumour ; Rat ; Detection ; Fluorescence ; Laser ; Haematoporphyrin derivative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Laser-induced fluorescence has been used for the identification of brain tumours in rats, which have been previously given tumour-seeking haematoporphyrin derivative. A pulsed nitrogen laser (λ=337 nm) was used in conjunction with an optical multichannel analyzer. For both inoculated RG-2 and TCVC rat-brain-tumour models, the blue autofluorescence was strongly reduced in the tumour compared with normal brain tissue, and at the same time the characteristic red-drug signal increased. The contrast between tumour and normal tissue was strongly enhanced by forming the ratio between the two signals. Implications for possible improvement of tumour delineation in brain tumour surgery are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032454
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of hydrochlorothiazide on the pain threshold and on the antinociceptive activity of morphine, in rats (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 265-266 
    Details
    ISSN: 1420-9071
    Keywords: Rat ; hydrochlorothiazide ; pain threshold ; antinociceptive activity ; analgesic activity ; morphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hydrochlorothiazide, acutely injected in rats, has a weak analgesic activity per se and potentiates and prolongs the antinociceptive effect of morphine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02002628
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  • 6
    Electronic Resource
    Electronic Resource
    Nitrogen-fixing stem nodules on Aeschynomene afraspera (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 61-66 
    Details
    ISSN: 1432-0789
    Keywords: Stem nodulation ; Aeschynomene afraspera ; Legume ; Nitrogen fixation ; Acetylene reduction assay (ARA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Aeschynomene afraspera is a wild annual legume growing in periodically waterlogged soils in western Africa. This legume is characterized by a profuse stem nodulation. Nodules are formed on the stem at the emergence of lateral root primordia, called nodulation sites. These sites are irregularly distributed on vertical rows all along the stem and branches. Stem nodules are hemispherically shaped. Their outside is dark green and they contain a red-pigmented central zone. Stem nodules exhibit a high nitrogen-fixing potential. Acetylene reduction assays result in stem nodule activity of 309 μmol C2H4 g−1 dry nodule h−1. Field-grown stem nodulated Aeschynomene accumulated more N (51 g N m−2 in 10 weeks) than the root nodulated one. Because of this nitrogenfixing potential and its ability to grow in waterlogged conditions, A. afraspera could probably be introduced into tropical rice cropping systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280352
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  • 7
    Electronic Resource
    Electronic Resource
    Azospirillum — plant root associations: A review (1989)
    Springer
    Biology and fertility of soils 8 (1989), S. 356-368 
    Details
    ISSN: 1432-0789
    Keywords: Plant-root associations ; Azospirillum spp ; Rhizosphere ; Nitrogen fixation ; Acetylene reduction assay (ARA) ; Phytohormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Bacteria of the genus Azospirillum are extensively studied for their plant-growth promoting effect following inoculation. Physiological and biochemical studies of these diazotrophic bacteria are now benefiting from recent breakthroughs in the development of genetic tools for Azospirilum. Moreover, the identification and cloning of Azospirillum genes involved in N2 fixation, plant interaction, and phytohormone production have given new life to many research projects on Azospirillum. The finding that Azospirillum genes can complement specific mutations in other intensively studied rhizosphere bacteria like Rhizobia will certainly trigger the exploration of new areas in rhizosphere biology. Therefore a review of the Azospirillum-plant interactions is particularly timely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263169
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of inoculum rate on the performance of chickpea (Cicer arietinum L.) Rhizobium strains in the field (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 83-87 
    Details
    ISSN: 1432-0789
    Keywords: Inoculation ; Inoculum dose ; Nitrogen fixation ; Chickpea ; Rhizobium spp. ; Cicer arietinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The influence of three inoculum rates on the performance of three chickpea (Cicer arietinum L.) Rhizobium strains was examined in the field on a Mollisol soil. Increasing amounts of inoculum improved the performance of the strains. A normal dose (104 cells per seed) applied at different intervals gave non-significant increases in nodulation, nitrogenase activity (acetylene reduction assay), nitrogen uptake and grain yield. A ten-fold increase in inoculum increased nodule number, shoot dry weight, nitrogenase activity (ARA) and grain yield, but increases over the control were significant only for nodule dry weight and nitrogen uptake by shoot and grain. The highest level of inoculum (100 × normal) significantly increased nodule dry weight, grain yield, total nitrogenase activity (ARA) and nitrogen uptake by shoot and grain. Strain TAL 620 was more effective than the other two. Combined nitrogen (60 kg N ha−1) suppressed nodulation and nitrogenase activity (ARA).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264351
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  • 9
    Electronic Resource
    Electronic Resource
    Presence and dispersal of infective Frankia in peat and meadow soils in Sweden (1988)
    Springer
    Biology and fertility of soils 6 (1988), S. 39-44 
    Details
    ISSN: 1432-0789
    Keywords: Alnus ; Energy forestry ; Frankia ; Meadow soil ; Nitrogen fixation ; Nodulation ; Peat soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Use of the N2-fixing grey alder, Alnus incana (L.) Moench, as a short-rotation crop for energy production is currently being explored. To evaluate the need for inoculation of alders, the distribution of infective propagules of Frankia in the soil at potential sites for alder plantations was examined. Uninoculated grey alder seedlings were grown in three types of soil. Frequent nodulation was found in a meadow soil which had been free from actinorhizal plants for nearly 60 years, but the alder seedlings failed to nodulate in peat soil from two different bog sites. One of these bogs had been exploited for peat and the surface layer of the peat had been removed, so that the soil samples were taken from deep layers of the peat. At the other site, an area of cultivated peat, there were no infective propagules of Frankia in plots without alders; the infective Frankia was present in plots only where it had been introduced by inoculated alders. There was no detectable air-borne dispersal of Frankia. Instead, water movement might account for the dispersal of Frankia in peat. Although the apparent absence of Frankia in these peat soils necessitates inoculation of alder seedlings before planting out, this makes it possible to introduce and maintain Frankia strains with selected beneficial characteristics, since there is no competition from an indigenous Frankia flora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257918
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  • 10
    Electronic Resource
    Electronic Resource
    Impact of nodule damage by Rivellia angulata on N2-fixation, growth, and yield of pigeonpea (Cajanus cajan L. Millsp.) grown in a Vertisol (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 95-100 
    Details
    ISSN: 1432-0789
    Keywords: Nodule damage ; Rivellia angulata ; Nitrogen fixation ; Cajanus cajan ; Pigeonpea ; Vertisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Damage caused by Rivellia angulata larvae to pigeonpea root nodules at the ICRISAT center in India was greater in the crop grown on Vertisols (up to 86%) compared to that on Alfisols (20%). Attempts to quantify the field effects of nodule damage on growth and yield of pigeonpea in a Vertisol, involving many heavy applications of soil insecticides (aldrin and hexachlorocyclohexane) failed because the insecticides did not control the pest and adversely affected the growth of the pigeonpea and the subsequent crop of sorghum (Sorgorum bicolor L. Moench). The impact of nodule damage on pigeonpea growth, yield and nutrient uptake was successfully studied in greenhouse-grown plants at three N levels. In this pot study, artificial inoculation with Rivellia sp. led to substantial nodule damage (70%). The results of this damage were a significant overall reduction in nodule dry weight (46%), acetylene reduction activity (31%), total leaf area (36%), chlorophyll content of leaves (39%) and shoot dry weight (23%) 68 days after sowing. At maturity, Rivellia sp. infestation caused significant reductions in top dry weight (22%), root and nodule dry weight (27%), seed dry weight (14%), and total N (29%) and P uptake (19%). The problems and prospects of manipulating nodule damage so as to reduce N losses in pigeonpea are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292565
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  • 11
    Electronic Resource
    Electronic Resource
    Yield response of spring wheat cultivars (Triticum aestivum and T. turgidum) to inoculation with Azospirillum brasilense under field conditions (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 27-35 
    Details
    ISSN: 1432-0789
    Keywords: Triticum aestivum ; T. turgidum ; Nitrogen fixation ; Field inoculation ; Acetylene reduction assay (ARA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Eight commercial Israeli spring wheat cultivars (six Triticum aestivum and two T. turgidum) grown with 40 and 120 kg N/ha were tested for responses to inoculation with Azospirillum brasilense. At the low level of N fertilization (40 kg/ha), five cultivars showed significant increases in plant dry weight measured at the milky ripe stage; however, by maturation only the cultivar “Miriam” showed a significant increase in grain yield. Two cultivars, which had shown a positive inoculation effect at the earlier stages, had a significant decrease in grain yield. No significant effect of inoculation was found at the high N level. To confirm those results, four wheat (T. aestivum) cultivars were tested separately over 4 years in 4 different locations under varying N levels. Only Miriam showed a consistently positive effect of Azospirillum inoculation on grain yield. Inoculation increased the number of roots per plant on Miriam compared with uninoculated plants. This effect was found at all N levels. Nutrient (N, P and K) accumulation and number of fertile tillers per unit area were also enhanced by Azospirillum, but these parameters were greatly affected by the level of applied N. It is suggested that the positive response of the spring wheat cultivar “Miriam” to Azospirillum inoculation is due to its capacity to escape water stresses at the end of the growth season.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280347
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  • 12
    Electronic Resource
    Electronic Resource
    Nitrogen fixation and balance studies of rice soil (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 15-19 
    Details
    ISSN: 1432-0789
    Keywords: Nitrogen fixation ; N-balance studies ; Azolla ; Blue-green algae ; Chemical N fertilization ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A nitrogen balance study conducted in ceramic pots under net house conditions for four seasons showed that flooded rice soil leaves a positive nitrogen balance (N increase) in soil after rice cropping in both fertilized and unfertilized soil. Recovery of nitrogen from rice soil was more than its input in unfertilized soil, but it was reverse in fertilized soil. Incorporation of Azolla or BGA twice as basal and 20 days after transplanting (DAT) alone or in combination showed higher nitrogen balance and N2-fixation (N gain) in soil than in that where it was applied once either as basal or 20 DAT. Planted soil showed more N2-fixation than that of fallow rice, and flooded soil fixed more nitrogen in comparison to non-flooded soil in light but less in dark. Soil exposed to light fixed more nitrogen than that of unexposed soil in both flooded and non-flooded conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280345
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  • 13
    Electronic Resource
    Electronic Resource
    Stimulation of root exudation of rice seedlings by Azospirillum strains: carbon budget under gnotobiotic conditions (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 9-14 
    Details
    ISSN: 1432-0789
    Keywords: Rhizosphere ; Nitrogen fixation ; Root exudates ; Soil bacteria ; Carbon budget ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The association of rice seedlings (cv. Delta) with different strains of Azospirillum was studied under monoxenic conditions in the dark. Axenic 3-day-old seedlings were obtained on a C- and N-free medium and inoculated with 6 · 107 bacteria per plant in a closed vial. Seven days later, different components of a carbon budget were evaluated on them and on sterile controls: respired CO2, carbon of shoot and roots, bacterial and soluble carbon in the medium. Two strains (A. lipoferum 4B and A. brasilense A95) isolated from the rhizosphere of rice caused an increase in exudation, + 36% and + 17% respectively compared with sterile control. Shoot carbon incorporation and respiration were reduced by inoculation. A third strain (A. brasilense R07) caused no significant change in exudation. A. lipoferum B7C isolated from maize did not stimulate rice exudation either. We further investigated a possible effect of nitrogen fixation on this phenomenon: inhibition of nitrogen fixation by 10% C2H2 did not modify the extent of C exudation by rice associated with A. lipoferum 4B or with the non-motile A. lipoferum 4T.
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    URL: http://dx.doi.org/10.1007/BF00280344
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  • 14
    Electronic Resource
    Electronic Resource
    Variation in nitrogen fixation among populations ofFrankia sp. andCeanothus sp. in actinorhizal association (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 269-274 
    Details
    ISSN: 1432-0789
    Keywords: Nitrogen fixation ; Frankia-Ceanothus spp. association ; Acetylene reduction assay (ARA) ; Microsymbiont population ; Nodules ; Actinomycetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wildland shrub improvement is needed for sound range and disturbed land revegetation practice. The possibility of selecting superior N2-fixingFrankia-Ceanothus spp. actinorhizal associations was examined. Greenhouse tests were used to expose various soil-borne microsymbiont andCeanothus sp. population accessions in reciprocal combination. The acetylene reduction rate was used as a measure of N2-fixation capacity. There was no significant interaction between host and microsymbiont regardless of source for all variables measured. The acetylene reduction rate, nodule number and mass, plant biomass, and root: shoot ratio were significantly different among soil sources. The acetylene reduction rate was not significantly different amongCeanothus sp. accessions. Neither was it strongly correlated with other variables. It was concluded that the N2-fixation rate is more a function ofFrankia sp. than the hostCeanothus sp. in actinorhizal associations. It appears possible to select soil sources with superior N2-fixing microsymbiont populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709660
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  • 15
    Electronic Resource
    Electronic Resource
    Seeding vs. vegetative propagations of the stem-nodulating green manure Sesbania rostrata (1988)
    Springer
    Biology and fertility of soils 6 (1988), S. 279-281 
    Details
    ISSN: 1432-0789
    Keywords: Sesbania rostrata ; Green manure ; Biofertilizer ; Nitrogen fixation ; Stem nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ratooning and stem cutting were compared with seeding in order to reduce the amount of seeds of Sesbania rostrata for green-manure growth. Both methods increased the biofertilizer yield highly significantly within a 6-week growth period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261012
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  • 16
    Electronic Resource
    Electronic Resource
    Immunological homologies between yeast ribosomal protein L2 and rat liver ribosomal proteins L4 and L24 (1988)
    Springer
    Current genetics 13 (1988), S. 235-239 
    Details
    ISSN: 1432-0983
    Keywords: Ribosomal protein ; Immunological homology ; Yeast ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Polyclonal antibodies raised against ribosomal protein (r-protein) L2 of Schizosaccharomyces pombe were used to check for cross-reaktions with total r-proteins of rat liver. Using this procedure, the rat liver r-proteins, L4 and L24, were identified as being immunologically related to yeast L2. In addtional, homologies between rat liver L4 and L24 were detected. The possible implications for the regulation of r-protein synthesis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387769
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  • 17
    Electronic Resource
    Electronic Resource
    Intra- and interspecies analyses of the carcinoembryonic antigen (CEA) gene family reveal independent evolution in primates and rodents (1989)
    Springer
    Journal of molecular evolution 29 (1989), S. 126-134 
    Details
    ISSN: 1432-1432
    Keywords: Carcinoembryonic antigen ; Evolution ; Gene family ; Human ; Rat ; Synonymous substitutions ; Silent molecular clock ; Evolutionary trees
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Various rodent and primate DNAs exhibit a stronger intra- than interspecies cross-hybridization with probes derived from the N-terminal domain exons of human and rat carcinoembryonic antigen (CEA)-like genes. Southern analyses also reveal that the human and rat CEA gene families are of similar complexity. We counted at least 10 different genes per human haploid genome. In the rat, approximately seven to nine different N-terminal domain exons that presumably represent different genes appear to be present. We were able to assign the corresponding genomic restriction endonuclease fragments to already isolated CEA gene family members of both human and rat. Highly similar subgroups, as found within the human CEA gene family, seem to be absent from the rat genome. Hybridization with an intron probe from the human nonspecific cross-reacting antigen (NCA) gene and analysis of DNA sequence data indicate the conservation of noncoding regions among CEA-like genes within primates, implicating that whole gene units may have been duplicated. With the help of a computer program and by calculating the rate of synonymous substitutions, evolutionary trees have been derived. From this, we propose that an independent parallel evolution, leading to different CEA gene families, must have taken place in, at least, the primate and rodent orders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02100111
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  • 18
    Electronic Resource
    Electronic Resource
    Qualitative and quantitative variability in different classes of proteins: Comparison of mouse and rat (1987)
    Springer
    Journal of molecular evolution 24 (1987), S. 260-271 
    Details
    ISSN: 1432-1432
    Keywords: Mouse ; Rat ; Two-dimensional electrophoresis ; Quantitative variability of proteins ; Qualitative variability of proteins ; Protein classes ; Membrane proteins ; Organ-specific proteins ; Regulatory genes ; Speciation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Proteins of membranes and cytosols were extracted from the livers and brains of mice (inbred strain DBA/6J) and rats (inbred strain DA/Han) and separated by two-dimensional electrophoresis (2-DE). The 2-DE patterns were compared with regard to qualitative (spot position) and quantitative (spot intensity) characteristics of the proteins of these two species. The following results were obtained: (1) Brain had more (higher percentage) conservative proteins (proteins found in both mice and rats) than liver; (2) plasma membranes had more conservative proteins than the cytosols; (3) organ-unspecific proteins contained more conservative proteins than relatively organ-specific proteins; (4) the pattern of distribution of genetic variability among different classes of proteins represented by findings 1–3 was the same for the qualitative and quantative characteristics of the proteins; and (5) some observations indicated that quantitative variability occurred more frequently among proteins than did qualitative variability. Our conclusion is that regulatory sequences in the DNA (regulatory genes) are subjected to functional constraints that differ in strength among different classes of proteins by the same ratios as the constraints acting on the structural genes. The overall effect of the selective pressure is, however, less stringent for regulatory genes than for structural genes. The results obtained here by comparing two different species are very similar to previous results we obtained by studying different subspecies (inbred strains of the mouse). From this finding arises a new concept: the study of molecular evolution on the basis of different classes of proteins. Our results were compared with data from the literature that were obtained in part from studies on cultured cells. The comparison suggested that cultured cells have lost their tissue-specific proteins, and so generate predominantly extremely conservative proteins.
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    Distribution of vitamin A in various organs of rats in relation to the quality and the quantity of dietary proteins (1987)
    Springer
    European journal of nutrition 26 (1987), S. 43-51 
    Details
    ISSN: 1436-6215
    Keywords: Dietary protein ; Vitamin A ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Es wurde der Einfluß von Qualität und Quantität von Nahrungsproteinen auf die Verteilung einer einzigen massiven Dosis von Vitamin A in verschiedenen Organen wachsender Wistar-Ratten untersucht. Die Untersuchungen wurden mit Casein- und Bengal-Gram-Diäten mit 20 % und 10 % Proteingehalt und auch mit radioaktiv markiertem Retinylacetat durchgeführt. Die Ergebnisse zeigen, daß die Leberspeicherung sowohl von Vitamin A aus der Nahrung als auch die einer einzigen starken Vitamin-A-Gabe (20 000 I.U.) stark herabgesetzt war bei Ratten, die nach der Bengal-Gram-Diät gefüttert wurden, verglichen mit Ratten, die auf Casein-Diät gesetzt waren. Im Gegensatz zur Leberspeicherung ist das Vitamin-A-Niveau im Plasma in allen Gruppen vergleichbar. Füttern niedriger Protein-Qualität reduzierte die Gewebeverteilung von [3H]-Retinylacetat sowohl bei Kontrollratten als auch bei solchen, denen eine massive Dosis Vitamin A gegeben wurde. Diese Untersuchung läßt vermuten, daß sowohl schlechte Qualität als auch unzureichende Mengen von Nahrungsproteinen nachteilige Einflüsse auf den Vitamin-A-Zustand wachsender Ratten haben.
    Notes: Summary The influence of the quality and the quantity of dietary proteins on the distribution of a single massive dose of vitamin A in various organs of growing Wistar strain rats has been studied by using casein and bengal gram diets at 20 % and 10 % protein levels. The distribution of [3H]-retinyl acetate in various tissues was also investigated in these dietary conditions. The results show that the hepatic storage of dietary as well as a single massive dose (20,000 I.U.) of vitamin A was profoundly decreased in the rats fed on bengal gram diets as compared to those fed on casein diets. Regardless of hepatic stores, the plasma vitamin A levels were comparable in all the groups. Feeding of low quality of protein reduced the tissue distribution of [3H]-retinyl acetate in control as well as rats given a massive dose of vitamin A. This study suggests that both the poor quality and the inadequate quantity of dietary protein are detrimental influences on the vitamin A status of the growing rats.
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    Tall gut formation in the rat embryo (1985)
    Springer
    Development genes and evolution 194 (1985), S. 429-432 
    Details
    ISSN: 1432-041X
    Keywords: Tail bud ; Tail gut ; Gut ; Organogenesis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The formation of the tail portion of the primitive gut was investigated by light and electron microscopy in 10- and 11-day rat embryos. The observations permit the conclusion that the tail gut does not form as a posterior extension of the hindgut but originates from the tail bud mesenchyme by mechanism analogous to the secondary neurulation. It includes cell condensation, aquisition of apicobasal polarity and the radial, rosette-like arrangement around a central cavity. These cells bear the cytological characteristics of both the absorptive epithelial cells and the mesenchymal cells at their apical (adluminal) and abluminal ends respectively.
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    URL: http://dx.doi.org/10.1007/BF00848557
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    Changes in brush-border enzyme activities of intestinal epithelial cells isolated from the villus-crypt axis during the early phase of alloxan diabetes in rats (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 482-484 
    Details
    ISSN: 1420-9071
    Keywords: Rat ; alloxan diabetes ; intestinal villus ; alkaline phosphatase ; sucrase ; epithelial cells ; villus-crypt axis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sucrase activity in enterocytes isolated from the villus crypt axis was found to increase in all regions of the villus from day 2 after induction of diabetes, and the increase continued until day 4. In contrast, alkaline phosphatase activity increased mainly in the apical one-third of the villus-crypt column, and the increase occurred abruptly on day 4 with increase in food intake.
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    URL: http://dx.doi.org/10.1007/BF01966159
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    Basal plasma corticosterone level after bilateral selective lesions of thee olfactory pathways in the rat (1986)
    Springer
    Cellular and molecular life sciences 42 (1986), S. 169-171 
    Details
    ISSN: 1420-9071
    Keywords: Rat ; olfactory pathway selective lesions ; plasma corticosterone ; lactacidemia ; adrenal glands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In comparison to control rats, basal plasma corticosterone level and lactacidemia significantly increased in rats submitted to a bilateral lesion of the lateral olfactory tract and/or the anterior branch of the anterior commissure. Only the anterior branch of the anterior commissure induced hyperglycemia; that of the lateral olfactory tract exerted an opposite effect.
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    URL: http://dx.doi.org/10.1007/BF01952451
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  • 23
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    Effects of β-hydroxybutyrate on rat embryos grown in culture (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 273-275 
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    ISSN: 1420-9071
    Keywords: Rat ; embryo ; embryo ; rat ; β-hydroxybutyrate ; diabetes ; maternal ; fetal malformation ; malformation ; fetal ; ketone bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to investigate further the relationship between maternal diabetes and fetal malformation, rat embryos were grown in vitro in the presence of β-hydroxybutyrate, one of the ketone bodies produced by diabetics. At 10 mM, β-hydroxybutyrate produced minor abnormalities and at 20 mM it produced major abnormalities in rat embryos.
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    URL: http://dx.doi.org/10.1007/BF02002633
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    Epilepsy and electromagnetic fields: effects of simulated atmospherics and 100-Hz magnetic fields on audiogenic seizure in rats (1988)
    Springer
    International journal of biometeorology 32 (1988), S. 17-20 
    Details
    ISSN: 1432-1254
    Keywords: Epilepsy ; Electromagnetic fields ; Rat ; Audiogenic seizure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract In order to study the possible association between epileptic seizures and natural electromagnetic fields, 32 female audiogenic seizure (AGS)-susceptible rats were exposed to simulated 10 kHz and 28 kHz atmospherics and to a sinusoidally oscillating magnetic field with a frequency of 100 Hz and field strength of 1 A/m. After the electromagnetic exposure, seizures were induced in the rats with a sound stimulus. The severity of the seizure was determined on an ordinal scale, the audiogenic response score (ARS). The time from the beginning of the sound stimulus to the onset of the seizure (seizure latency) and the duration of the convulsion was measured. No differences from the control experiments were found in the experiments with simulated atmospherics, but the 100 Hz magnetic field increased the seizure latency by about 13% (P〈0.02). The results do not support the hypothesis that natural atmospheric electromagnetic signals could affect the onset of epileptic seizures, but they suggest that AGS-susceptible rats may be a useful model for studying the biological effects of electromagnetic fields.
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    URL: http://dx.doi.org/10.1007/BF01623987
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    Demonstration of correlations between the 8 and 10 kHz atmospherics and the inflammatory reaction of rats after carrageenan injection (1988)
    Springer
    International journal of biometeorology 32 (1988), S. 201-204 
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    ISSN: 1432-1254
    Keywords: Atmospherics ; Carrageenan inflammation ; Rat ; Susceptibility ; Correlations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Between the mean daily density of 28 kHz atmospherics and the onset of epileptic fits there is a highly significant correlation coefficient (r) of 0.30; there is a negative coefficient of −0.20 between the fits and the mean daily density of 10 kHz atmospherics. The onset of heart infarction is correlated with 28 kHz atmospherics (r=0.15). Furthermore, we have discovered that sudden deafness is also correlated with certain configurations of atmospherics. In this paper we report the following correlation coefficients between the inflammatory reaction of rats to a carrageenan injection (rci) into a hind paw and the mean daily pulse rate of atmospherics of the same day:r=0.49 for the 8 kHz atmospherics (P〈0.02) andr=0.44 for the 10 kHz atmospherics (P〈0.04). The correlations between rci reaction and other atmospherics (12 and 28 kHz) are smaller and not significant. By the method of multiple linear regression we found a multipleR=0.54 between rci reaction and the 8 and 10 kHz atmospherics (the regression function for the rci reaction is 0.15+0.004×8 kHz+0.002×10 kHz,P〈0.05).
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    URL: http://dx.doi.org/10.1007/BF01045280
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    Production of gibberellins and indole-3-acetic acid by Rhizobium phaseoli in relation to nodulation of Phaseolus vulgaris roots (1988)
    Springer
    Planta 175 (1988), S. 532-538 
    Details
    ISSN: 1432-2048
    Keywords: Auxin (IAA), production by Rhizobium ; Gibberellin production by Rhizobium ; Mutant (Rhizobium) ; Nitrogen fixation ; Phaseolus (nodulation) ; Rhizobium (mutants) ; Root nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Similar ranges of gibberellins (GAs) were detected by high-performance liquid chromatography (HPLC)-immunoassay procedures in ten cultures of wild-type and mutant strains of Rhizobium phaseoli. The major GAs excreted into the culture medium were GA1 and GA4. These identifications were confirmed by combined gas chromatographymass spectrometry. The HPLC-immunoassays also detected smaller amounts of GA9- as well as GA20-like compounds, the latter being present in some but not all cultures. In addition to GAs, all strains excreted indole-3-acetic acid (IAA) but there was no obvious relationship between the amounts of GA and IAA that accumulated. The Rhizobium strains studied included nod − and fix − mutants, making it unlikely that the IAA- and GA-biosynthesis genes are closely linked to the genes for nodulation and nitrogen fixation. The HPLC-immunoassay analyses showed also that nodules and non-nodulated roots of Phaseolus vulgaris L. contained similar spectra of GAs to R. phaseoli culture media. The GA pools in roots and nodules were of similar size, indicating that Rhizobium does not make a major contribution to the GA content of the infected tissue.
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    Pathways of assimilation and transfer of fixed nitrogen in coralloid roots of cycad-Nostoc symbioses (1988)
    Springer
    Planta 176 (1988), S. 461-471 
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    ISSN: 1432-2048
    Keywords: Carbon dioxide fixation ; Citrulline ; Coralloid roots ; Cycads (nitrogen fixation) ; Nitrogen fixation ; Nitrogen transport ; Nostoc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freshly detached coralloid roots of several cycad species were found to bleed spontaneously from xylem, permitting identification of products of nitrogen transfer from symbiotic organ to host. Structural features relevant to the export of fixed N were described for Macrozamia riedlei (Fisch. ex Gaud.) Gardn. the principal species studied. Citrulline (Cit), glutamine (Gln) and glutamic acid (Glu), the latter usually in a lesser amount, were the principal translocated solutes in Macrozamia (5 spp.), Encephalartos (4 spp.) and Lepidozamia (1 sp.), while Gln and a smaller amount of Glu, but no Cit were present in xylem sap of Bowenia (1 sp.),and Cycas (2 spp.). Time-course studies of 15N enrichment of the different tissue zones and the xylem sap of 15N2-pulse-fed coralloid roots of M. riedlei showed earlier 15N incorporation into Gln than into Cit, and a subsequent net decline in the 15N of Gln of the coralloid-root tissues, whereas Cit labeling continued to increase in inner cortex and stele and in the xylem sap. Hydrolysis of the 15N-labeled Cit and Gln consistently demonstrated much more intense labeling of the respective carbamyl and amide groups than of the other N-atoms. Coralloid roots of M. riedlei pulse-fed 14CO2 in darkness showed 14C labeling of aspartic acid (Asp) and Cit in all tissue zones and of Cit of xylem bleeding sap. Lateral roots and uninfected apogeotropic roots of M. riedlei and M. moorei also incorporated 14CO2 into Cit. The 14C of Cit was restricted to the carbamyl-C. Comparable 15N2 and CO2-feeding studies on corallid roots of Cycas revoluta showed Gln to be the dominant product of N2 fixation, with Asp and alanine as other major 14C-labeled amino compounds, but a total absence of Cit in labeled or unlabeled form.
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    Nitrogen fixation in the lichen Lobaria pulmonaria in elevated atmospheric carbon dioxide (1989)
    Springer
    Oecologia 79 (1989), S. 566-568 
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    ISSN: 1432-1939
    Keywords: Carbon dioxide ; Lichen ; Lobaria ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thalli of Lobaria pulmonaria (L.) Hoffm., a nitrogen-fixing epiphyte common in mesic temperate forests, were collected in a Douglas-fir (Pseudotsuga menziesii Franco) forest near Corvallis, Oregon, and maintained for 20 to 40 days in controlled-environment chambers with atmospheric CO2 concentrations of 374 and 700 μll-1. Nitrogenase activity, which was assayed by the acetylene reduction method, was approximately doubled in the lichen maintained in elevated CO2. Increases in nitrogen fixation by lichens may be an important part of the integrated ecosystem response to rising CO2.
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    The effects of nitrogen fixation, soil nitrate, and defoliation on the growth, alkaloids, and nitrogen levels of Lupinus succulentus (Fabaceae) (1987)
    Springer
    Oecologia 74 (1987), S. 425-431 
    Details
    ISSN: 1432-1939
    Keywords: Lupinus succulentus ; Fabaceae ; Lupine ; Quinolizidine alkaloids ; Nitrogen fixation ; Defoliation ; Plant-herbivore interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We examined the effects of nitrogen nutrition and defoliation on the alkaloids, nitrogen levels, and growth of Lupinus succulentus by growing plants under five nitrogen/defoliation treatments: 1) fertilization with a high-nitrate nutrient solution, 2) fertilization with a low-nitrate solution, 3) inoculation with N-fixing bacteria but without available soil nitrogen, 4) high-nitrate solution plus periodic partial defoliation, and 5) low-nitrate plus defoliation. In the absence of defoliation, plants from both the N-fixing and high-N treatments had higher concentrations of alkaloids and nitrogen, and higher growth rates than the low-N plants. Periodic defoliation had little effect on the high-N plants, but defoliated N-fixing plants were severely stunted and had lower alkaloid and nitrogen levels. The experimental treatments also affected the relative concentrations of the alkaloids. Our results indicate that 1) alkaloid composition and concentration in L. succulentus are determined by both nitrogen availability and developmental state, 2) plants relying solely on N-fixation respond quite differently to defoliation than those with adequate soil nitrogen, and 3) the food value of the plant tissue can be affected by an interaction between the effects of defoliation and nitrogen status.
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    URL: http://dx.doi.org/10.1007/BF00378940
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    Melatonin accelerates reentrainment of the circadian rhythm of its own production after an 8-h advance of the light-dark cycle (1989)
    Springer
    Journal of comparative physiology 166 (1989), S. 97-102 
    Details
    ISSN: 1432-1351
    Keywords: Rat ; Melatonin ; Circadian rhythm ; 5-hydroxytryptophan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rhythm in melatonin production in the rat is driven by a circadian rhythm in the pineal N-acetyltransferase (NAT) activity. Rats adapted to an artificial lighting regime of 12 h of light and 12 h of darkness per day were exposed to an 8-h advance of the light-dark regime accomplished by the shortening of one dark period; the effect of melatonin, triazolam and fluoxetine, together with 5-hydroxytryptophan, on the reentrainment of the NAT rhythm was studied. In control rats, the NAT rhythm was abolished during the first 3 cycles following the advance shift. It reappeared during the 4th cycle; however, the phase relationship between the evening rise in activity and the morning decline was still compressed. Melatonin accelerated the NAT rhythm reentrainment. In rats treated chronically with melatonin at the new dark onset, the rhythm had already reappeared during the 3rd cycle, in the middle of the advanced night, and during the 4th cycle, the phase relationship between the evening onset and the morning decline of the NAT activity was the same as before the advance shift. In rats treated chronically with melatonin at the old dark onset or in those treated with melatonin 8 h, 5 h and 2 h after the new dark onset during the 1st, 2nd and 3rd cycle, respectively, following the advance shift, the NAT rhythm reappeared during the 3rd cycle as well but in the last third of the advanced night only. Neither triazolam nor fluoxetine together with 5-hydroxytryptophan administered around the new dark onset facilitated NAT rhythm reentrainment after the 8-h advance of the light-dark cycle.
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    Evidence for adenylylation/deadenylylation control of the glutamine synthetases of Rhodospirillum tenue and Rhodocyclus purpureus (1985)
    Springer
    Archives of microbiology 142 (1985), S. 103-108 
    Details
    ISSN: 1432-072X
    Keywords: Phototrophic bacteria ; Rhodospirillaceae ; Glutamine synthetase ; Nitrogen metabolism ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phylogenetically related phototrophic bacteria Rhodospirillum tenue and Rhodocyclus purpureus modulate activity of their glutamine synthetases by adenylylation/deadenylylation. Evidence for covalent modification includes the inhibitory effect of Mg2+ on the activity of glutamine synthetase extracted from cells of either species grown on excess ammonia, and the lack of Mg2+ inhibition of activity of the enzyme isolated from N2-(R. tenue) or glutamine (R. purpureus)-grown cells. In addition, snake venom phosphodiesterase treatment of glutamine synthetase from either species grown on excess ammonia relieved Mg2+ inhibition of the enzyme (as measured via the γ-glutamyl transferase assay), and changed the cation specificity from Mn2+ to Mg2+ (in the biosynthetic assay).
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    Assimilation of exogenous and dinitrogen-derived13NH 4 + byAnabaena azollae separated fromAzolla caroliniana Willd (1985)
    Springer
    Archives of microbiology 142 (1985), S. 229-233 
    Details
    ISSN: 1432-072X
    Keywords: Ammonium assimilation ; Excretion ; Anabaena azollae ; Azolla caroliniana ; Cyanobacteria ; Glutamine ; Glutamate formation ; Nitrogen fixation ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anabaena azollae was isolated fromAzolla caroliniana by the “gentle roller” method and differential centrifugation. Incubation of suchAnabaena preparations for 10 min with [13N]N2 resulted in the formation of four radioactive compounds; ammonium, glutamine, glutamate and alanine. Ammonium accounted for 66% of the total radioactivity recovered and 58% of the ammonium was in an extracellular fraction. Since essentially no extracellular13N-labeled organic compounds were found, it appears that ammonium is the compound most probably made available toAzolla during dinitrogen-dependent growth of the association. The kinetics of incorporation of exogenous13NH 4 + into glutamine and glutamate were characteristic of a precursor (glutamine)-product (glutamate) relationship and consistent with assimilation by the glutamine synthetase-glutamate synthase pathway. The results of experiments using the glutamine synthetase inhibitor, methionine sulfoximine, the glutamate synthase inhibitor, diazo-oxonorleucine, and increasing the ammonium concentration to greater than 1 mM, provided evidence for assimilation primarily by the glutamine synthetase-glutamate synthase pathway with little or no contribution from biosynthetic glutamate dehydrogenase. While showing that N2 fixation and NH 4 + assimilation were not tightly coupled metabolic processes in symbioticAnabaena, these results reflect a composite picture and do not indicate the extent to which ammonium assimilatory enzymes might be regulated in filaments associated with specific stages in theAzolla-Anabaena developmental profile.
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    Oxygen protection of nitrogenase in the aerobically nitrogen fixing, non-heterocystous cyanobacterium Oscillatoria sp. (1985)
    Springer
    Archives of microbiology 143 (1985), S. 72-76 
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    ISSN: 1432-072X
    Keywords: Oscillatoria ; Cyanobacteria ; Nitrogen fixation ; Oxygen protection of N2-ase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oscillatoria sp. strain 23 is a filamentous, non-heterocystous cyanobacterium that fixes nitrogen aerobically. Although, in this organism nitrogenase is inactivated by oxygen a high tolerance is observed. Up to a pO2 of 0.15 atm, oxygen does not have any measurable effects on acetylene reduction. Higher concentrations of oxygen inhibited the activity to a relatively high degree. Evidence for two mechanisms of oxygen protection of nitrogenase in this cyanobacterium was obtained. A high rate of synthesis of nitrogenase may allow the organism to maintain a certain amount of active enzyme under aerobic conditions. Secondly, a switch off/on mechanism may reversibly convert the active enzyme into a non-active form which is insensitive to oxygen inactivation after a sudden and short-term exposure to high oxygen concentrations. It is conceived that these mechanisms in addition to a temporal separation of nitrogen fixation from oxygenic photosynthesis sufficiently explain the regulation process of aerobic nitrogen fixation in this organism.
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    Nitrogenase activity in the non-heterocystous cyanobacterium Oscillatoria sp. grown under alternating light-dark cycles (1985)
    Springer
    Archives of microbiology 143 (1985), S. 67-71 
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    ISSN: 1432-072X
    Keywords: Oscillatoria ; Cyanobacteria ; Nitrogen fixation ; Light-dark cycles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The non-heterocystous cyanobacterium Oscillatoria sp. strain 23 fixes nitrogen under aerobic conditions. If nitrate-grown cultures were transferred to a medium free of combined nitrogen, nitrogenase was induced within about 1 day. The acetylene reduction showed a diurnal variation under conditions of continuous light. Maximum rates of acetylene reduction steadily increased during 8 successive days. When grown under alternating light-dark cycles, Oscillatoria sp. fixes nitrogen preferably in the dark period. For dark periods longer than 8 h, nitrogenase activity is only present during the dark period. For dark periods of 8 h and less, however, nitrogenase activity appears before the beginning of the dark period. This is most pronounced in cultures grown in a 20 h light – 4 h dark cycle. In that case, nitrogenase activity appears 3–4 h before the beginning of the dark period. According to the light-dark regime applied, nitrogenase activity was observed during 8–11 h. Oscillatoria sp. grown under 16 h light and 8 h dark cycle, also induced nitrogenase at the usual point of time, when suddenly transferred to conditions of continuous light. The activity appeared exactly at the point of time where the dark period used to begin. No nitrogenase activity was observed when chloramphenicol was added to the cultures 3 h before the onset of the dark period. This observation indicated that for each cycle, de novo nitrogenase synthesis is necessary.
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    Indigenous plasmids and cultural characteristics of rhizobia nodulating chickpeas (Cicer arietinum L.) (1986)
    Springer
    Archives of microbiology 146 (1986), S. 239-244 
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    ISSN: 1432-072X
    Keywords: Cicer arietinum ; nif Genes ; Plasmids ; Rhizobia ; DNA/DNA hybridization ; Nitrogen fixation ; Chickpeas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined 27 strains of chickpea rhizobia from different geographic origins for indigenous plasmids, location and organization of nitrogen fixation (nif) genes, and cultural properties currently used to separate fast- and slow-growing groups of rhizobia. By using an in-well lysis and electrophoresis procedure one to three plasmids of molecular weights ranging from 35 to higher than 380 Mdal were demonstrated in each of 19 strains, whereas no plasmids were detected in the eight remaining strains. Nitrogenase structural genes homologous to Rhizobium meliloti nifHD, were not detected in plasmids of 26 out of the 27 strains tested. Hybridization of EcoRI digested total DNA from these 26 strains to the nif probe from R. meliloti indicated that the organization of nifHD genes was highly conserved in chickpea rhizobia. The only exception was strain IC-72 M which harboured a plasmid of 140 Mdal with homology to the R. meliloti nif DNA and exhibited also a unique organization of nifHD genes. The chickpea rhizobia strains showed a wide variation of growth rates (generation times ranged from 4.0 to 14.5 h) in yeast extract-mannitol medium but appear to be relatively homogeneous in terms of acid production in this medium and acid reaction in litmus milk. Although strains with fast and slow growth rates were identified, DNA/DNA hybridization experiments using a nifHD-specific probe, and the cultural properties examined so far do not support the separation of chickpea rhizobia into two distinct groups of the classical fast- and slow-growing types of rhizobia.
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    Melanin production encoded by a cryptic plasmid in a Rhizobium leguminosarum strain (1988)
    Springer
    Archives of microbiology 150 (1988), S. 326-332 
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    ISSN: 1432-072X
    Keywords: Rhizobium leguminosarum ; Plasmids ; Melanin ; Nodulation ; Nitrogen fixation ; Plasmid curing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhizobium leguminosarum strain VF39, isolated from nodules of field-grown faba beans in the Federal Republic of Germany, was shown to contain six plasmids ranging in molecular weight from 90 to 400 Md. Hybridisation to nif gene probes, plasmid curing, and mobilisation to other strains of Rhizobium and to Agrobacterium showed that the third largest plasmid, pRleVF39d (220 Md), carried genes for nodulation and nitrogen fixation. This plasmid was incompatible with pRL10JI, the Sym plasmid of R. leguminosarum strain JB300. Of the other plasmids, the two smallest (pRleVF39a and pRleVF39b, 90 and 160 Md respectively) were shown to be self-transmissible at a low frequency. Although melanin production is as yet unreported in strains of R. leguminosarum biovar viceae, strain VF39 produced a dark pigment, which, since it was not produced on minimal media and its production was greatly enhanced by the presence of tyrosine in the media, is probably melanin-like. Derivatives of VF39 cured of pRleVF39a no longer produced this pigment, but regained the ability to produce it when this plasmid was transferred into them. Strains of Agrobacterium tumefaciens, R. meliloti, and some strains of R. leguminosarum carrying pRleVF39a did not produce this pigment, indicating perhaps that some genes elsewhere on the VF39 genome are also involved in pigment production. Plasmid pRleVF39a appeared to be incompatible with the cryptic Rhizobium plasmids pRle336b and pRL8JI (both ca. 100 Md), but was compatible with the R. leguminosarum biovar phaseoli Sym plasmids pRP1JI, pRP2JI and pRph51a, all of which also code for melanin production. The absence of pRleVF39a in cured derivatives of VF39 had no effect on the symbiotic performance or competitive ability of this strain.
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    New types of acetate-oxidizing, sulfate-reducing Desulfobacter species, D. hydrogenophilus sp. nov., D. latus sp. nov., and D. curvatus sp. nov. (1987)
    Springer
    Archives of microbiology 148 (1987), S. 286-291 
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    ISSN: 1432-072X
    Keywords: Sulfate-reducing bacteria ; Desulfobacter species ; Acetate ; Hydrogen ; Autotrophic growth ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sulfate-reducing bacteria with oval to rod-shaped cells (strains AcRS1, AcRS2) and vibrio-shaped cells (strains AcRM3, AcRM4, AcRM5) differing by size were isolated from anaerobic marine sediment with acetate as the only electron donor. A vibrio-shaped type (strain AcKo) was also isolated from freshwater sediment. Two strains (AcRS1, AcRM3) used ethanol and pyruvate in addition to acetate, and one strain (AcRS1) grew autotrophically with H2, sulfate and CO2. Higher fatty acids or lactate were never utilized. All isolates were able to grow in ammonia-free medium in the presence of N2. Nitrogenase activity under such conditions was demonstrated by the acetylene reduction test. The facultatively lithoautotrophic strain (AcRS1), a strain (AcRS2) with unusually large cells (2×5 μm), and a vibrio-shaped strain (AcRM3) are described as new Desulfobacter species, D. hydrogenophilus, D. latus, and D. curvatus, respectively.
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    The calcium requirement for functional vesicle development and nitrogen fixation by Frankia strains EAN1pec and CpI1 (1987)
    Springer
    Archives of microbiology 149 (1987), S. 24-29 
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    ISSN: 1432-072X
    Keywords: Frankia ; Nitrogen fixation ; Calcium ; Vesicle development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A calcium requirement was shown for both vesicle development and nitrogenase activity by Frankia strains EAN1pec and CpI1. Washing cells with EGTA or EDTA inhibited both vesicle development and nitrogenase activity. The inhibition of both was reversed by the addition of calcium. A variety of agents known to affect calcium-dependent biological processes, such as a Ca-ATPase inhibitor, Ca-channel blockers, Ca-ionophores, calmodulin antagonists and the local anaesthetics, tetracaine and dibucaine, inhibited nitrogenase activity. Respiratory studies showed that a CN-insensitive respiration process occurred only under nitrogen derepressing conditions. Respiration by NH4Cl-grown cells was completely inhibited by KCN while N2-grown cells were inhibited by only 70%. Removal of calcium ions by EGTA or by the addition of dibucaine or tetracaine blocked the CN-insensitive respiration. This CN-insensitive respiration may be involved in protecting nitrogenase inside the vesicles from oxygen.
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    Regulation of nitrogenase activity by covalent modification in Chromatium vinosum (1985)
    Springer
    Archives of microbiology 141 (1985), S. 40-43 
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    ISSN: 1432-072X
    Keywords: Nitrogenase ; Nitrogen fixation ; Regulation ; Photosynthetic bacteria ; Chromatium ; Ammonia switch off
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogenase in Chromatium vinosum was rapidly, but reversibly inhibited by NH 4 + . Activity of the Fe protin component of nitrogenase required both Mn2+ and activating enzyme. Activating enzyme from Rhodospirillum rubrum could replace Chromatium chromatophores in activating the Chromatium Fe protein, and conversely, a protein fraction prepared from Chromatium chromatophores was effective in activating R. rubrum Fe protein. Inactive Chromatium Fe protein contained a peptide covalently modified by a phosphate-containing molecule, which migrated the same in SDS-polyacrylamide gels as the modified subunit of R. rubrum Fe protein. In sum, these observations suggest that Chromatium nitrogenase activity is regulated by a covalent modification of the Fe protein in a manner similar to that of R. rubrum.
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    Electron donation to nitrogenase in heterocysts of cyanobacteria (1985)
    Springer
    Archives of microbiology 143 (1985), S. 185-191 
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    ISSN: 1432-072X
    Keywords: Heterocyst ; Pyruvate: ferredoxin oxidoreductase ; Nitrogen fixation ; Electron transport to nitrogenase ; Ferredoxin ; Cyanobacteria ; Anabaena cylindrica ; Anabaena variabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various electron donors were found to stimulate C2H2 reduction (N2 fixation) by isolated heterocysts from Anabaena variabilis and Anabaena cylindrica. Intermediates of glycolysis and the tricarboxylic acid cycle as well as unphosphorylated sugars like glucose, fructose and erythrose were among these electron donors. The transfer of electrons from donors like H2, NADH, glyoxylate and glycollate was strictly light-dependent, whereas others like NADPH or pyruvate plus coenzyme A supported C2H2 reduction also in the dark. In all cases, the overall activity was enhanced by light. The stimulation by light was more distinct with heterocysts from A. variabilis than with heterocysts from A. cylindrica. The present communication establishes that pyruvate supports C2H2 reduction by heterocysts from either A. variabilis or A. cylindrica with rates comparable to those with other electron donors. Pyruvate could, however, support C2H2 reduction only in the presence of coenzyme A, and the concentrations of both coenzyme A and pyruvate were crucial. A pyruvate-dependent reduction of ferredoxin by extracts from heterocysts was recorded spectrophotometrically. Glyoxylate, which is an inhibitor of thiamine pyrophosphate-dependent decarboxylations, inhibited pyruvate-dependent C2H2 reduction. This result supports the conclusion that pyruvate is metabolised by pyruvate: ferredoxin oxidoreductase in heterocysts. High concentrations of pyruvate and other electron donors inhibited C2H2 reduction which suggests that nitrogenase activity in heterocysts may be controlled by the availability of electron donors.
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    Aspects of nitrogen fixation in Chlorobium (1986)
    Springer
    Archives of microbiology 143 (1986), S. 330-336 
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    ISSN: 1432-072X
    Keywords: Phototrophic bacteria ; Green sulfur bacteria ; Chtorobium ; Nitrogen fixation ; Nitrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four strains of the green sulfur bacterium Chlorobium were studied in respect to nitrogen nutrition and nitrogen fixation. All strains grew on ammonia, N2, or glutamine as sole nitrogen sources; certain strains also grew on other amino acids. Acetylene-reducing activity was detectable in all strains grown on N2 or on amino acids (except for glutamine). In N2 grown Chlorobium thiosulfatophilum strain 8327 1 mM ammonia served to “switch-off” nitrogenase activity, but the effect of ammonia was much less dramatic in glutamate or limiting ammonia grown cells. The glutamine synthetase inhibitor methionine sulfoximine inhibited ammonia “switch-off” in all but one strain. Cell extracts of glutamate grown strain 8327 reduced acetylene and required Mg2+ and dithionite, but not Mn2+, for activity. Partially purified preparations of Rhodospirillum rubrum nitrogenase reductase (iron protein) activating enzyme slightly stimulated acetylene reduction in extracts of strain 8327, but no evidence for an indigenous Chlorobium activating enzyme was obtained. The results suggest that certain Chlorobium strains are fairly versatile in their nitrogen nutrition and that at least in vivo, nitrogenase activity in green bacteria is controlled by ammonia in a fashion similar to that described in nonsulfur purple bacteria and in Chromatium.
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    Symbiotically defective histidine auxotrophs of Bradyrhizobium japonicum (1986)
    Springer
    Archives of microbiology 144 (1986), S. 334-339 
    Details
    ISSN: 1432-072X
    Keywords: Transposon mutagenesis ; Soybean ; Nitrogen fixation ; Root nodules ; Auxotrophy ; Bradyrhizobium japonicum ; Glycine ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four histidine auxotrophs of Bradyrhizobium japonicum strain USDA 122 were isolated by random transposon Tn5 mutagenesis. These mutants arose from different, single transposition events as shown by the comparison of EcoRI and XhoI-generated Tn5 flanking sequences of genomic DNA. The mutants grew on minimal medium supplemented with l-histidine or l-histidinol but failed to grow with l-histidinol phosphate. While two of the muants were symbiotically defective and did not form nodules on Glycine max cvs. Lee and Peking and on Glycine soja, the other two mutants were symbiotically competent. Reversion to prototrophy occurred at a frequency of about 10-7 on growth medium without added antibiotics, but prototrophs could not be isolated from growth medium containing 200 μg/ml kanamycin and streptomycin. The prototrophic revertants formed nodules on all the soybean cultivars examined. When histidine was supplied to the plant growth medium, both nodulation deficient mutants formed effective symbioses. On histidine unamended plants, nodules were observed infrequently. Three classes of bacterial colonies were isolated from such infrequent nodules: class 1 were kanamycin resistant-auxotrophs; class 2 were kanamycin sensitive-prototrophs; and class 3 were kanamycin-sensitive auxotrophs. Our results suggest that two Tn5 insertion mutations in B. japonicum leading to histidine auxotrophy, affect nodulation in some way. These mutations are in regions that show no homology to the Rhizobium meliloti common nodulation genes.
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    Nitrogen fixation in strains ofAzotobacter chroococcum bearing deletions of a cluster of genes coding for nitrogenase (1986)
    Springer
    Archives of microbiology 146 (1986), S. 74-79 
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    ISSN: 1432-072X
    Keywords: Azotobacter chroococcum ; Nitrogen fixation ; Nitrogenase genes ; Nif gene reiteration ; Deletion mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Strains of the obligately aerobic nitrogen fixing organismAzotobacter chroococcum were constructed which contained defined chromosomal deletions in which the nitrogenase structural genenifHDK cluster (nifH for the polypeptide of the Fe-protein component of nitrogenase andnifD andnifK for the alpha and beta subunits respectively of the MoFe-protein component of the enzyme) was replaced by a kanamycin resistance gene. N2 fixation was nevertheless observed in deletion strains though only in a molybdenum-deficient medium or in spontaneously arising tungstate-resistant derivatives. In comparison with the parent strain growing in molybdenum-sufficient medium, diazotrophic growth was slow and the nitrogenase activity in vivo was characterised by disproportionately low rates of C2H2-reduction compared to H2-evolution and relative insensitivity of H2-evolution to inhibition by C2H2. The findings show reiteration of functional structural genes for nitrogenase inA. chroococcum consistent with our previous observation of twonifH genes in this organism and detection in this work of a secondnifK-like sequence in the genomes of both parent and deletion strains whenA. chroococcum nifK DNA was used as a probe.
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    Some properties of arctic rhizobia (1986)
    Springer
    Archives of microbiology 146 (1986), S. 12-18 
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    ISSN: 1432-072X
    Keywords: Arctic rhizobia ; Arctic legumes ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-eight strains of Rhizobium isolated from the root nodules of three species of legumes indigenous to the high tundra (Astragalus alpinus, Oxytropis maydelliana andOxytropis arctobia) are phenotypically heterogenous with respect to intrinsic antibiotic resistance, expression of nitrogenase activityex planta and plasmid content. All of the strains possess a 250–300 kb plasmid and are homologous to each other on the genomic DNA level but have little DNA homology with selected reference strains of well characterized species of rhizobia. The arctic rhizobia have an optimum growth temperature of 23°C and can grow slowly at 5°C. The DNA from four of the isolates, which were selected for detailed investigation, have sequences homologous tonif andnod genes fromRhizobium trifolii.
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    Comparative physiology of nitrogenase activity and vesicle development for Frankia strains CpI1, ACN1 ag , EAN1pec and EUN1f (1987)
    Springer
    Archives of microbiology 147 (1987), S. 383-388 
    Details
    ISSN: 1432-072X
    Keywords: Frankia ; Nitrogen fixation ; Vesicle development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between nitrogen fixation and development of a specialized cell structure, called the vesicle, was studied using four Frankia isolates. Nitrogenase activity was repressed in all four strains during growth with ammonia. Strain CpI1 formed no vesicles during NH4 growth. Strains ACN1 ag , EAN1pec and EUN1f produced low numbers of vesicles in the presence of ammonia. Following transfer to nitrogen-free media, a parallel increase in nitrogenase activity and vesicle numbers occurred with all four isolates. Appearance of nitrogenase activity was more rapid in those strains that possessed some vesicles at the time of shift to N2 as a nitrogen source. The ratio of vesicle numbers to level of nitrogenase activity varied widely among the four strains and in response to different growth conditions and culture age of the individual strains. Optimum conditions of temperature, carbon and energy source, nitrogen source and availability of iron and molybdenum were different for each of the four strains. Those conditions that significantly reduced nitrogenase activity were always associated with decreased numbers of vesicles.
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    Occurrence of nitrogen fixation among Vibrio spp. (1988)
    Springer
    Archives of microbiology 150 (1988), S. 224-229 
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    ISSN: 1432-072X
    Keywords: Vibrio ; V. diazotrophicus ; V. natriegens ; V. pelagius ; V. cincinnatiensis ; Nitrogenase ; Nitrogen fixation ; Oxygen sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Virtually all Vibrio spp. known and available in culture collections and several newly isolated Vibrio sp. were tested for their ability to fix molecular nitrogen, using the acetylene reduction technique, the fixation of the heavy isotope 15N, and by growth on media devoid of combined nitrogen. Among the 27 species tested, four, including V. diazotrophicus, proved to be nitrogenase-positive. The potential of nitrogen fixation was now also discovered in V. natriegens, V. pelagius and V. cincinnatiensis. Among the 9 newly isolated strains, 4 were nitrogenase-positive. These strains were classified as V. diazotrophicus on the basis of DNA homology studies. Nitrogenase was only induced during growth under anaerobic conditions. Dissolved oxygen as low as 1 μM inhibited nitrogenase completely. This inhibition at low oxygen concentration, however, was reversible. 50–100 μM dissolved oxygen inhibited nitrogenase irreversibly.
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    Isolation and characterization of hydrogenase-negative mutants of Azorhizobium caulinodans ORS571 (1988)
    Springer
    Archives of microbiology 150 (1988), S. 595-599 
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    ISSN: 1432-072X
    Keywords: Azorhizobium caulinodans ORS571 ; Hydrogenase ; Nitrogen fixation ; Chemostat cultures ; H2/N2 ratio ; ATP/2e value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hydrogenase-negative (Hup-) mutants of Azorhizobium caulinodans ORS571 were isolated by means of Tn5 mutagenesis. The colony test used for screening for Hup- strains was based on the absence of reduction of triphenyltetrazolium chloride with hydrogen. Suspensions from cultures of the mutant strains grown under derepressing conditions did not use hydrogen with methylene blue or oxygen as the hydrogen acceptor. The mutants were shown to carry single Tn5 insertions at different locations in the A. caulinodans genome. Molar growth yields (corrected for poly-β-hydroxybutyrate formation) in chemostat cultures of the mutants were similar to those of the wild type. Molar growth yields of the mutants were not increased by passing additional hydrogen through chemostat cultures, which is in agreement with the hydrogenase-negative phenotype of the mutants. H2/N2 ratios (mol H2 formed per mol N2 fixed) were calculated from the hydrogen content of the effluent gas and the N-content of the bacterial dry weight. Low H2/N2 ratios (between 1.2 and 1.9) were found in both energy-limited (oxygen or succinate) cultures and in cultures limited by the supply of an anabolic substrate (Mg2+). ATP/2e values (mol ATP used at the transport of 2e to nitrogen or H+) were calculated from the H2/N2 ratios and the molar growth yields of nitrogen-fixing and ammonia-assimilating cultures. ATP/2e values were between 7 and 11. It was concluded that the calculated ATP/2e values comprise not only 4 mol ATP used at the transport of 2e through nitrogenase but also energy equivalents needed for reversed electron flow from NADH to the low-potential hydrogen donor used by nitrogenase.
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    Derivatives of Rhizobium meliloti strains carrying a plasmid of Rhizobium leguminosarum specifying hydrogen uptake and pea-specific symbiotic functions (1985)
    Springer
    Archives of microbiology 140 (1985), S. 352-357 
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    ISSN: 1432-072X
    Keywords: Alfalfa ; Conjugation ; Cross inoculation ; Host specificity ; Hydrogen uptake ; Nodulation ; Nitrogen fixation ; Rhizobium ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract pIJ1008, a Rhizobium leguminosarum plasmid which determines hydrogen uptake ability and symbiotic functions in pea was transferable to three of seven natural isolates of R. meliloti tested. In these three strains, pIJ1008 was maintained stably with the respective sym megaplasmid indigenous to each R. meliloti strain. These strains carrying both plasmids nodulated alfalfa but not pea. By reisolation and examination of the strains from alfalfa nodule tissue, it was shown that pIJ1008 continued to be maintained but that pea-nodulation ability was suppressed. In one strain of R. meliloti which carries a 200 kb cryptic plasmid (in addition to a megaplasmid), the transfer and selection for pIJ1008 resulted in the loss of the cryptic plasmid. In three separate plant growth experiments, alfalfa nodules induced by each of the R. meliloti strain carrying both sym plasmids were assayed for hydrogen uptake activity. The average activity was 40-, 3.5-and 2-fold higher than with the respective pIJ1008-free strains. However, this higher activity was not accompanied by an increase in plant biomass or nitrogen content of shoots.
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    Expression ofKlebsiella pneumoniae nif genes inProteus mirabilis (1985)
    Springer
    Archives of microbiology 142 (1985), S. 289-294 
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    ISSN: 1432-072X
    Keywords: Proteus mirabilis ; Nitrogen fixation ; nif genes ; nif plasmids ; Klebsiella pneumoniae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Self-transmissible plasmids carryinghis andnif genes fromKlebsiella pneumoniae have been introduced into threehis mutants ofProteus mirabilis: strains 5006-1, WR19 and WR20. Expression ofhis by the transconjugants was unequivocal, if slightly temperature-sensitive, but none was Nif+ when tested for acetylene reduction in anaerobic glucose medium using inocula from rich or glucose-minimal aerobic agar cultures. Succinate or pyruvate in place of glucose, low glucose, lower temperature or elevated Na2MoO4 did not allownif expression and no nitrogenase MoFe-protein peptide was detected immunologically after exposure to conditions in which diazotrophic enterobacteria, normal or genetically constructed, derepressnif. One strain,P. mirabilis WR19, carrying thehis nif Kmr plasmid pMF250 was examined in detail. Thenif activator genenifA was introduced on the plasmid pCK1. Such derivatives remained Nif- when tested, after aerobic growth on rich agar media, with normal or low glucose, with succinate or with elevated Mo. However, pre-conditioning by aerobic growth on glucose-minimal agar led to subsequent anaerobic expression ofnif in glucose medium from pMF250 in WR19 carrying pCK1. NH 4 + or proline could serve as N-source in the glucose-minimal agar. Maximum activity was about 5% of that ofK. pneumoniae in our assay conditions. Material cross-reacting with anti-serum to the nitrogenase MoFe protein was formed. Nitrogenase activity was not ‘switched off’ by NH 4 + .P. mirabilis WR19 (pCK1) showed NH 4 + -constitutive temperature-sensitive kanamycin resistance (anif-related phenotype of this plasmid) in aerobic glucose minimal medium. Expression ofnif inP. mirabilis WR19 (pCK1, pMF250) was NH 4 + -repressible despite the constitutivenifA character of pCK1 and introduction of thentrA + plasmid pMM17 did not alter this phenotype. However, pCK1 did not give rise to NH 4 + -constitutive diazotrophy in the wild-typeK. pneumoniae M5al. A construct of WR19 carrying pMF250 and constitutiventrC plasmid (pMD45) remained Nif- even after pre-growth on glucose-minimal media. We conclude (a) thatP. mirabilis forms a gene product functionally equivalent to that ofntrA inK. pneumoniae, (b) that it forms no functional equivalent of thentrC product in our growth conditions. The need for pre-conditioning on aerobic glucose media remains perplexing.
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    Concurrent evolution of nitrogenase genes and 16S rRNA in Rhizobium species and other nitrogen fixing bacteria (1985)
    Springer
    Archives of microbiology 142 (1985), S. 342-348 
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    ISSN: 1432-072X
    Keywords: Evolution ; Nif genes ; Nitrogen fixation ; Nitrogenase ; Nucleotide sequence ; Phylogeny ; Rhizobium ; 16S rRNA cataloguing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It was known that nitrogenase genes and proteins are well conserved even though they are present in a large variety of phylogenetically diverse nitrogen fixing bacteria. This has lead to the speculation, among others, that nitrogen fixation (nif) genes were spread by lateral gene transfer relatively late in evolution. Here we report an attempt to test this hypothesis. We had previously established the complete nucleotide sequences of the three nitrogenase genes from Bradyrhizobium japonicum, and have now analyzed their homologies (or the amino acid sequence homologies of their gene products) with corresponding genes (and proteins) from other nitrogen fixing bacteria. There was a considerable sequence conservation which certainly reflects the strict structural requirements of the nitrogenase iron-sulfur proteins for catalytic functioning. Despite this, the sequences were divergent enough to classify them into an evolutionary scheme that was conceptually not different from the phylogenetic positions, based on 16S rRNA homology, of the species or genera harboring these genes. Only the relation of nif genes of slow-growing rhizobia (to which B. japonicum belongs) and fast-growing rhizobia was unexpectedly distant. We have, therefore, performed oligonucleotide cataloguing of their 16S rRNA, and found that there was indeed only a similarity of S AB=0.53 between fast- and slowgrowing rhizobia. In conclusion, the results suggest that nif genes may have evolved to a large degree in a similar fashion as the bacteria which carry them. This interpretation would speak against the idea of a recent lateral distribution of nif genes among microorganisms.
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    Bradyrhizobium japonicum mutants defective in root-nodule bacteroid development and nitrogen fixation (1986)
    Springer
    Archives of microbiology 144 (1986), S. 355-366 
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    ISSN: 1432-072X
    Keywords: Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
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    Inorganic nitrogen metabolism in two cellulose-degrading clostridia (1986)
    Springer
    Archives of microbiology 145 (1986), S. 159-161 
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    ISSN: 1432-072X
    Keywords: Clostridium cellobioparum ; Clostridium thermocellum ; Ammonium assimilation ; Nitrogen fixation ; Nitrogen control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inorganic nitrogen metabolism in two cellulose degrading clostridia, the mesophile Clostridium cellobioparum and the thermophile Clostridium thermocellum was investigated. Both strains show acetylene reduction (i.e. possibly nitrogenase activity), contain glutamine synthetase, glutamate dehydrogenase and glutamate-dependent transaminases. C. cellobioparum additionally contains a NADH-dependent glutamate synthase and a NH 4 + -repressible glycine dehydrogenase (NADPH). Remarkably, acetylene reduction in C. thermocellum is not repressed by ammonium, casting doubt whether this activity is due to nitrogenase. The results are compared with the data from other saccharolytic clostridia.
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    Isolation of cyanobacterial heterocysts with high and sustained dinitrogen-fixation capacity supported by endogenous reductants (1986)
    Springer
    Archives of microbiology 145 (1986), S. 241-247 
    Details
    ISSN: 1432-072X
    Keywords: Heterocyst isolation ; Osmoregulators ; Cyanobacteria ; Nitrogen fixation ; Anabaena variabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method is described for the preparation of cyanobacterial heterocysts with high nitrogen-fixation (acetylene-reduction) activity supported by endogenous reductants. The starting material was Anabaena variabilis ATCC 29413 grown in the light in the presence of fructose. Heterocysts produced from such cyanobacteria were more active than those from photoautotrophically-grown A. variabilis, presumably because higher reserves of carbohydrate were stored within the heterocysts. It proved important to avoid subjecting the cyanobacteria to low temperatures under aerobic conditions, as inhibition of respiration appeared to lead to inactivation of nitrogenase. Low temperatures were not harmful in the absence of O2. A number of potential osmoregulators at various concentrations were tested for use in heterocyst isolation. The optimal concentration (0.2M sucrose) proved to be a compromise between adequate osmotic protection for isolated heterocysts and avoidance of inhibition of nitrogenase by high osmotic strength. Isolated heterocysts without added reductants such as H2 had about half the nitrogen-fixation activity expected on the basis of intact filaments. H2 did not increase the rate of acetylene reduction, suggesting that the supply of reductant from heterocyst metabolism did not limit nitrogen fixation under these conditions. Such heterocysts had linear rates of acetylene reduction for at least 2 h, and retained their full potential for at least 12 h when stored at 0°C under N2.
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    Isolation and characterization of alkene-utilizing Xanthobacter spp. (1986)
    Springer
    Archives of microbiology 145 (1986), S. 403-407 
    Details
    ISSN: 1432-072X
    Keywords: Propene ; 1-Butene ; Xanthobacter ; Mono-oxygenase ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Yellow-pigmented bacteria showing typical characteristics of Xanthobacter spp. were isolated from enrichments with propene and 1-butene, using classical techniques. The generation time for growth on propene and 1-butene of these bacteria ranged from 5 to 7h. A NADH-dependent mono-oxygenase was identified in cell-free extract of Xanthobacter Py2. This mono-oxygenase was not influenced by potential inhibitors tested indicating that propene mono-oxygenase is different from other hydrocarbon mono-oxygenases described until now. Nitrogenase activity could be measured using the acetylene reduction assay with propene as energy source, because acetylene did not inhibit the mono-oxygenase activity.
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    Localization of nitrogenase in vesicles of Frankia sp. Cc1.17 by immunogoldlabelling on ultrathin cryosections (1987)
    Springer
    Archives of microbiology 146 (1987), S. 327-331 
    Details
    ISSN: 1432-072X
    Keywords: Actinomycetes ; Nitrogen fixation ; Symbiosis ; Immunocytochemistry ; Ultracryotomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Immunogoldlabelling on ultrathin cryosections of Frankia sp. Cc1.17 showed specific labelling of nitrogenase in the spherical cells called vesicles. No label was found in the hyphae in any cells grown on a medium with combined nitrogen, nor in those to which no specific antiserum was added. Similar results were obtained with cultures grown under high (20%) and low (2%) oxygen tension in the gas phase.
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    Vanadium and molybdenum requirement for the fixation of molecular nitrogen by two Methanosarcina strains (1988)
    Springer
    Archives of microbiology 151 (1988), S. 44-48 
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    ISSN: 1432-072X
    Keywords: Vanadium ; Molybdenum ; Methanogenesis ; Nitrogen fixation ; Archaebacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogen fixation of the Methanosarcina barkeri strains “Fusaro” (DSM 804) and “227” (DSM 1538) was found to be dependent on the presence of vanadium or molybdenum whereby molybdenum (added as Na2-molybdate) was preferred to vanadium (added as VCl3). Strain “227” showed less pronounced effects on diazotrophic growth with respect to vanadium and molybdenum. Rhenium (ReCl3) or tungsten (Na2-tungstate) could not replace vanadium or molybdenum. The optimum concentrations were found to be 2μM for vanadium and 5μM for molybdenum (strain “Fusaro”). This Mo optimum of methanogenesis was 10-fold higher with N2 than with NH4Cl as nitrogen source. A vanadium requirement with NH4Cl could not be detected. No interferences were observed if molybdenum and vanadium were added simultaneously under diazotrophic conditions. Growth yields were smallest for strain “227” grown diazotrophically ( $$Y_{CH_3 OH}$$ =0.6g dw/mol in the presence of vanadium and $$Y_{CH_3 OH}$$ =0.9g dw/mol in the presence of molybdenum), obviously higher for strain “Fusaro” grown diazotrophically ( $$Y_{CH_3 OH}$$ =1.15g dw/mol in the presence of V and $$Y_{CH_3 OH}$$ =1.4g dw/mol with Mo) and highest if M. barkeri was grown on NH4Cl as N-source ( $$Y_{CH_3 OH}$$ =3.4g dw/mol with Mo, strain “Fusaro”).
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    Energy transduction efficiencies in nitrogenous oxide respirations of Azospirillum brasilense Sp7 (1989)
    Springer
    Archives of microbiology 151 (1989), S. 445-453 
    Details
    ISSN: 1432-072X
    Keywords: Denitrification ; Growth yield measurements ; Nitrate respiration ; Nitrogen fixation ; Proton translocations in respirations ; Azospirillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For Azospirillum brasilense Sp7, the energy transformation efficiencies were measured in anaerobic respirations with either nitrate, nitrite or nitrous oxide as respiratory electron acceptors by determining the maximal molar growth yields and the H+-translocations using the oxidant pulse method. In continuous cultures grown with malate limiting, the maximal molar growth yields (Y s max -values) were essentially the same with O2 or N2O but were 1/3 and 2/3 lower with NO 2 - or NO 3 - , respectively, as respiratory electron acceptors. Both the maximal molar growth yields and the maintenance energy coefficients were surprisingly high when Azospirillum was grown with nitrite as the sole electron acceptor and source for N-assimilation. Growth under N2-fixing conditions drastically reduced the Y s max -values in the N2O and O2-respiring cells. In the H+-translocation measurements, the $$\vec H^ + $$ /oxidant ratios were 5.6 for O2→H2O, 2.5–2.8 for NO 3 - →NO 2 - , 2.2 for NO 2 - →N2O and 3.1 for N2O→N2 respirations when the cells were preincubated with valinomycin and K+. All the values were enhanced when the experiments were performed with valinomycin plus methyltriphenylphosphonium (=TPMP+) cation. The uncoupler carbonyl cyanide-m-chlorophenyl-hydrazone diminished the H+-excretion indicating that this translocation was due to vectorial flow across the membrane. In the absence of any ionophore, nitrate and nitrite respirations were accompanied by a H+-uptake $$(NO_3^ - \to N_2 = - 2.9 \vec H^ + /NO_3^ - and NO_2^ - \to N_2 = - 2.5 \vec H^ + /NO_2^ - )$$ . Any significant H+-translocation could not be detected in N2O- and O2-respirations under these conditions. It is concluded that nitrate reduction proceeds inside the cytoplasmic membrane, whereas nitrite is reduced extramembraneously. The data are not conclusive for the location of nitrous oxide reductase. The maximal molar growth yield determinations and the absence of any H+-uptake in untreated cells indicate a cytoplasmic orientation of the enzyme similar to the terminal cytochrome oxidase of respiration. The low H+-extrusion values for N2O-respiration compared to O2-respiration in cells treated with valinomycin plus TPMP+ are, however, not in accord with such an interpretation.
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    Cloning of a DNA region from Bradyrhizobium japonicum encoding pleiotropic functions in heme metabolism and respiration (1989)
    Springer
    Archives of microbiology 151 (1989), S. 203-212 
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    ISSN: 1432-072X
    Keywords: Bradyrhizobium ; Gene cloning ; Heme ; Marker exchange mutagenesis ; Nitrogen fixation ; Respiration ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Random and site-directed Tn5-induced mutagenesis of Bradyrhizobium japonicum yielded two mutations, one in strain 2960 and the other in strain 2606::Tn5-20, which mapped close to each other but in separate genes. The corresponding wild-type genes were cloned, and their approximate location on the cloned DNA was determined. Mutant 2960 was Fix- and formed green nodules on soybean, whereas strain 2606::Tn5-20 had ca. 4% of wild-type Fix activity and formed white nodules. Cytochrome oxidase assays (Nadi tests) showed a negative reaction with both mutants, indicating a functional deficiency of cytochrome c or its terminal oxidase or both. However, the mutants grew well under aerobic conditions on minimal media with different carbon sources. Furthermore, mutant 2960 had a reduced activity in hydrogen uptake, was unable to grow anaerobically with nitrate as the terminal electron acceptor and 2960-infected soybean nodules contained little, if any, functional leghemoglobin. Southern blot analysis showed that a B. japonicum heme biosynthesis mutant [strain LO505: O'Brian MR, Kirshbom PM, Maier RJ (1987) Proc Natl Acad Sci USA 84: 8390–8393] had its mutation close to the Tn5 insertion site of our mutant 2606::Tn5-20. This finding, combined with the observed phenotypes, suggested that the genes affected in mutants 2960 and 2606::Tn5-20 were involved in some steps of heme biosynthesis thus explaining the pleiotropic respiratory deficiencies of the mutants. Similar to strain LO505, the mutant 2606::Tn5-20 (but not 2960) was defective in the activity of protoporphyrinogen IX oxidase which catalyzes the penultimate step in the heme biosynthesis pathway. This suggests that one of the two cloned genes may code for this enzyme.
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    Regulation of nitrogenase levels in Anabaena sp. ATCC 33047 and other filamentous cyanobacteria (1985)
    Springer
    Archives of microbiology 141 (1985), S. 105-111 
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    ISSN: 1432-072X
    Keywords: Ammonia ; Anabaena ; Cyanobacteria ; Nitrogen fixation ; Nitrogenase ; Nostoc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Incubation in the dark of photoautotrophically grown N2-fixing heterocystous cyanobacteria leads to a loss of nitrogenase activity. Original levels of nitrogenase activity are rapidly regained upon re-illumination of the filaments, in a process dependent on de novo protein synthesis. Ammonia, acting indirectly through some of its metabolic derivatives, inhibits the light-promoted development of nitrogenase activity in filaments of Anabaena sp. ATCC 33047 and several other cyanobacteria containing mature heterocysts. The ammonia-mediated control system is also operative in N2-fixing filaments in the absence of any added source of combined nitrogen, with the ammonia resulting from N2-fixation already partially inhibiting full expression of nitrogenase. High nitrogenase levels, about two-fold higher than those in normal N2-fixing Anabaena sp. ATCC 33047, are found in cell suspensions which have been treated with the glutamine synthetase inhibitor l-methionine-d,l-sulfoximine or subjected to nitrogen starvation. Filaments treated in either way are insensitive to the ammonia-promoted inhibition of nitrogenase development, although this insensitivity is only transitory for the nitrogen-starved filaments, which become ammonia-sensitive once they regain their normal nitrogen status.
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    Ethylenediamine uptake and metabolism in the cyanobacterium Anabaena variabilis (1985)
    Springer
    Archives of microbiology 141 (1985), S. 244-248 
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    ISSN: 1432-072X
    Keywords: Ammonia analogues ; Anabaena variabilis ; Cyanobacteria ; Ethylenediamine ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacterium Anabaena variabilis showed a pH dependent uptake of ethylenediamine. No uptake of ethylenediamine was detected at pH 7.0. At higher pH values (e.g. pH 8.0 and pH 9.0) accumulation did occur and was attributed to diffusion of uncharged ethylenediamine in response to a pH gradient. A biphasic pattern of uptake was observed at these higher pH values. Treatment with l-methionine-d,l-sulphoximine (MSX) to inactivate glutamine synthetase (GS) inhibited the second slower phase of uptake without any significant alteration of the initial uptake. Therefore for sustained uptake, metabolism of ethylenediamine via GS was required. NH 4 + did not alter the uptake of ethylenediamine. Ethylenediamine was converted in the second phase of uptake to an analogue of glutamine which could not be detected in uptake experiments at pH 7.0 or in uptake experiments at pH 9.0 following pretreatment of cells with MSX. Ethylenediamine treatment inhibited nitrogenase activity and this inhibition was greatest at high pH values.
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    Denitrification and nitrogen fixation by Azospirillum (1985)
    Springer
    Archives of microbiology 141 (1985), S. 364-370 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Denitrification ; Associative symbiosis ; Acetylene reduction ; Nitrous oxide formation ; Azospirillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A model system is described where Azospirillum and germinated wheat seeds were grown in association for a week and then assayed for nitrogen fixation (C2H2-reduction) and denitrification (N2O-formation) activities. The association performed C2H2-reduction and N2O-formation under microaerobic conditions. Both activities were measurable after already 3–5 h of incubation with substantial rates and were strictly dependent on the presence of both plants and bacteria. During the week of the growth of the association, the bacteria had lived exclusively from the carbon compounds supplied by the roots of the plants. C2H2-reduction activity by the association was more or less the same with all the Azospirillum brasilense strains, but lower with A. lipoferum and with the A. amazonense strains tested. Two nitrogenase negative mutants of Azospirillum brasilense showed virtually no activity in the association. C2H2-reduction activity was strongly dependent on the growth temperature of the association. Denitrification (N2O-formation) was high also at higher temperatures and at pH-values in the medium around 7.8 but not at neutrality and was strictly dependent on nitrate. The Azospirillum strain used strongly determined the rate of the N2O-formation in the association. It is suggested that Azospirillum may be beneficial to crops particularly under tropical conditions.
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    Deletion analysis of the nitrogen fixation regulatory gene, nifL of Klebsiella pneumoniae (1989)
    Springer
    Archives of microbiology 151 (1989), S. 180-182 
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    ISSN: 1432-072X
    Keywords: Klebsiella pneumoniae ; Nitrogen fixation ; nifL ; Regulation ; Oxygen control ; Nitrogen control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A number of in-frame deletions have been constructed in the Klebsiella pneumoniae regulatory gene nifL. The effects of each nifL mutation on NifA-mediated expression from the nifH promoter of K. pneumoniae have then been assessed with respect to both nitrogen and oxygen control. These experiments indicate that, in contrast to the situation with the homologous regulatory proteins NtrB and NtrC, NifA activity is not impaired in the absence of NifL. We conclude that the only function of NifL is to inactivate NifA in response to an increase in the nitrogen or oxygen status of the cell.
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    The relationship between hydrogen metabolism, sulfate reduction and nitrogen fixation in sulfate reducers (1987)
    Springer
    Journal of industrial microbiology and biotechnology 1 (1987), S. 383-388 
    Details
    ISSN: 1476-5535
    Keywords: Sulfate-reducing bacteria ; Hydrogen metabolism ; Nitrogen fixation ; Deuterium-proton exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Hydrogenase and nitrogenase activities of sulfate-reducing bacteria allow their adaptation to different nutritional habits even under adverse conditions. These exceptional capabilities of adaptation are important factors in the understanding of their predominant role in problems related to anaerobic metal corrosion. Although the D2−H+ exchange reaction indicated thatDesulfovibrio desulfuricans strain Berre-Sol andDesulfovibrio gigas hydrogenases were reversible, the predominant activity in vivo was hydrogen uptake. Hydrogen production was restricted to some particular conditions such as sulfate or nitrogen starvation. Under diazotrophic conditions, a transient hydrogen evolution was followed by uptake when dinitrogen was effectively fixed. In contrast, hydrogen evolution proceeded when acetylene was substituted as the nitrogenase substrate. Hydrogen can thus serve as an electron donor in sulfate reduction and nitrogen metabolism.
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    Utilization of nitrate by bacteroids of Bradyrhizobium japonicum in the soybean root nodule (1988)
    Springer
    Planta 174 (1988), S. 51-58 
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    ISSN: 1432-2048
    Keywords: Bacteroid ; Bradyrhizobium ; Glycine (N2 fixation) ; Nitrate reductase ; Nitrite reductase ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacteroids of Bradyrhizobium japonicum strain CB1809, unlike CC705, do not have a high level of constitutive nitrate reductase (NR; EC 1.7.99.4) in the soybean (Glycine max. Merr.) nodule. Ex planta both strains have a high activity of NR when cultured on 5 mM nitrate at 2% O2 (v/v). Nitrite reductase (NiR) was active in cultured cells of bradyrhizobia, but activity with succinate as electron donor was not detected in freshly-isolated bacteroids. A low activity was measured with reduced methyl viologen. When bacteroids of CC705 were incubated with nitrate there was a rapid production of nitrite which resulted in repression of NR. Subsequently when NiR was induced, nitrite was utilized and NR activity recovered. Nitrate reductase was induced in bacteroids of strain CB1809 when they were incubated in-vitro with nitrate or nitrite. Increase in NR activity was prevented by rifampicin (10 μg· ml-1) or chloramphenicol (50 μg·ml-1). Nitrite-reductase activity in bacteroids of strain CB1809 was induced in parallel with NR. When nitrate was supplied to soybeans nodulated with strain CC705, nitrite was detected in nodule extracts prepared in aqueous media and it accumulated during storage (1°C) and on further incubation at 25°C. Nitrite was not detected in nodule extracts prepared in ethanol. Thus nitrite accumulation in nodule tissue appears to occur only after maceration and although bacteroids of some strains of B. japonicum have a high level of a constitutive NR, they do not appear to reduce nitrate in the nodule because this anion does not gain access to the bacteroid zone. Soybeans nodulated with strains CC705 and CB1809 were equally sensitive to nitrate inhibition of N2 fixation.
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    Cellular compartmentation of ureide biogenesis in root nodules of cowpea (Vigna unguiculata (L.) Walp.) (1987)
    Springer
    Planta 172 (1987), S. 162-175 
    Details
    ISSN: 1432-2048
    Keywords: Nitrogen fixation ; Peroxisome ; Root nodules ; Ureide biogenesis ; Uricase ; Vigna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cowpea (Vigna unguiculata (L.) Walp.) nodules have been investigated by means of cytochemical and immunocytochemical procedures at the ultrastructural level in order to assess the role of the uninfected cells in ureide biogenesis. Uricase activity in the nodules was shown by cytochemical methods to be localized exclusively in the numberous large peroxisomes confined to the uninfected cells; the small peroxisomes in the infected cells did not stain for uricase. Uricase was also localized in the peroxisomes of uninfected cells by immunogold techniques employing polyclonal antibodies against nodule-specific uricase of soybean. There was no labeling above background of any structures in the infected cells. The results indicate that the uninfected cells are essential for ureide biogenesis in cowpea. Although tubular endoplasmic reticulum, the presumptive site of allantoinase, increases greatly in the uninfected cells during nodule development, it virtually disappears as the nodules mature. The inconsistency between the disappearance of the tubular endoplasmic reticulum from older nodules and the high allantoinase activity reported for older plants remains to be explained.
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    Fixation of [13N]N2 and transfer of fixed nitrogen in the Anthoceros-Nostoc symbiotic association (1985)
    Springer
    Planta 164 (1985), S. 406-414 
    Details
    ISSN: 1432-2048
    Keywords: Ammonia/ammonium (assimilation, excretion) ; Anthoceros ; Bryophyta ; Cyanobacteria ; Nitrogen fixation ; Nostoc ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The initial product of fixation of [13N]N2 by pure cultures of the reconstituted symbiotic association between Anthoceros punctatus L. and Nostoc sp. strain ac 7801 was ammonium; it accounted for 75% of the total radioactivity recovered in methanolic extracts after 0.5 min and 14% after 10 min of incubation. Glutamine and glutamate were the primary organic products synthesized from [13N]N2 after incubation times of 0.5–10 min. The kinetics of labeling of these two amino acids were characteristic of a precursor (glutamine) and product (glutamate) relationship. Results of inhibition experiments with methionine sulfoximine (MSX) and diazo-oxonorleucine were also consistent with the assimilation of N2-derived NH 4 + by Anthoceros-Nostoc through the sequential activities of glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.7.1), with little or no assimilation by glutamate dehydrogenase (EC 1.3.1.3). Isolated symbiotic Nostoc assimilated exogenous 13NH 4 + into glutamine and glutamate and their formation was inhibited by MSX, indicating operation of the glutamine synthetase-glutamate synthase (GS-GOGAT) pathway: However, relative to free-living cultures, isolated symbiotic Nostoc assimilated 80% less exogenous ammonium into glutamine and glutamate, implying that symbiotic Nostoc could assimilate only a fraction of N2-derived NH 4 + . This implication was tested by using Anthoceros associations reconstituted with wild-type or MSX-resistant strains of Nostoc incubated with [13N]N2 in the presence of MSX. The results of these experiments indicated that, in situ, symbiotic Nostoc assimilated about 10% of the N2-derived NH 4 + and that NH 4 + was made available to Anthoceros tissue where it was apparently assimilated by the GS-GOGAT pathway. Since less than 1% of the fixed N2 was lost to the suspension medium, it appears that transfer of NH 4 + from symbiont to host tissue was very efficient in this extracellular symbiotic association.
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    Acetylene reduction, H2 evolution and 15N2 fixation in the Alnus incana-Frankia symbiosis (1986)
    Springer
    Planta 167 (1986), S. 382-386 
    Details
    ISSN: 1432-2048
    Keywords: Acetylene/nitrogen molar ratio ; Alnus-Frankia symbiosis ; Nitrogen fixation ; Nitrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acetylene reduction, 15N2 reduction and H2 evolution were measured in root systems of intact plants of grey alder (Alnus incana (L.) Moench) in symbiosis with Frankia. The ratios of C2H2: 15N2 were compared with C2H2:N2 ratios calculated from C2H2 reduction and H2 evolution, and with C2H2:N2 ratios calculated from accumulated C2H4 production and nitrogen content. It was possible to calculate C2H2:N2 ratios from C2H2 reduction and H2 evolution because this source of Frankia did not show any hydrogenase activity. The ratios obtained using the different methods ranged from 2.72 to 4.42, but these values were not significantly different. It was also shown that enriched 15N could be detected in the shoot after a 1-h incubation of the root-system. It is concluded that the measurement of H2 evolution in combination with C2H2 reduction represents a nondestructive assay for nitrogen fixation in a Frankia symbiosis which shows no detectable hydrogenase activity.
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    Location of two isoenzymes of NADH-dependent glutamate synthase in root nodules of Phaseolus vulgaris L. (1989)
    Springer
    Planta 179 (1989), S. 441-447 
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    ISSN: 1432-2048
    Keywords: Glutamate synthase ; Glutamine synthetase ; Nitrogen fixation ; Phaseolus (glutamate synthase) ; Plastid (glutamate synthase) ; Root nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The two isoenzymes of NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14), previously identified in root nodules of Phaseolus vulgaris L., have both been shown to be located in root-nodule plastids. The nodule specific NADH-GOGAT II accounts for the majority of the activity in root nodules, and is present almost exclusively in the central tissue of the nodule. However about 20% of NADH-GOGAT I activity is present in the nodule cortex, at about the same specific activity as this isoenzyme is found in the central tissue. Glutamine synthetase (GS; EC 6.3.1.2) occurs predominantly as the γ polypeptide in the central tissue, whereas in the cortex, the enzyme is represented mainly by the β polypeptide. Over 90% of both GS and NADH-GOGAT activities are located in the central tissue of the nodule and GS activity exceeds NADH-GOGAT activity by about twofold in this region. Using the above information, a model for the subcellular location and stoichiometry of nitrogen metabolism in the central tissue of P. vulgaris root nodules is presented.
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    Interaction between alfalfa cultivars and Rhizobium strains for nitrogen Fixation (1986)
    Springer
    Theoretical and applied genetics 71 (1986), S. 724-729 
    Details
    ISSN: 1432-2242
    Keywords: Nitrogen fixation ; Alfalfa cultivars ; Rhizobium strains ; Acetylene reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two experiments were conducted in the greenhouse to study the interaction between alfalfa cultivars (Medicago sativa L. and M. falcata L.) and strains of Rhizobium meliloti Dang. for acetylene reduction rate, plant height and dry weights of shoot, root and whole plant. Fifteen alfalfa cultivars were inoculated with 10 strains of Rhizobium in Experiment I. Variance component analysis revealed that more than 30% of the total variance was due to alfalfa cultivars for acetylene reduction rate and 26% was accounted for by Rhizobium strains. More than 36% of the total variation was attributed to the interaction between alfalfa cultivars and Rhizobium strains for this character. Twenty-five host cultivars and 11 Rhizobium strains were included in Experiment II. The results also showed that the interaction of alfalfa cultivars and Rhizobium strains contributed the largest portion of the total variation for dry weights of shoot, root and whole plant and acetylene reduction rate. The results clearly demonstrated that the non-additive effects were the major component of variation for these characters associated with nitrogen fixation in alfalfa. Therefore, an effective way of improving nitrogen fixation in alfalfa is to select for a favourable combination of specific Rhizobium strains and alfalfa cultivars.
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    URL: http://dx.doi.org/10.1007/BF00263270
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    Induced genetic variability in Rhizobium leguminosarum for nitrogen fixation parameters in Vicia faba L. (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 433-435 
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    ISSN: 1432-2242
    Keywords: Rhizobium ; Irradiation ; Nitrogen fixation ; Vicia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Sumary The objective of this work was to know the behaviour and variability of Rhizobium leguminosarum after irradiation. The induced variation was tested under greenhouse conditions on the variety JV 3 of broad beans (Vicia faba) in six replications. Induced genetic variabilty was observed for strain, parent and mutant versus parent. Out of 24 irradiated strains, strain 93-32 performed better with a greater number of nodules and higher dry weight of nodules per plant and biological yield. Environment played an important role in the expression of characters observed. High heritability and genetic advance of these traits indicated that the nitrogen fixation ability of Rhizobium can easily be improved by selection.
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    URL: http://dx.doi.org/10.1007/BF00265308
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    Intracellular pathways of receptor-bound GnRH agonist in pituitary gonadotropes (1985)
    Springer
    Cell & tissue research 239 (1985), S. 3-8 
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    ISSN: 1432-0878
    Keywords: GnRH receptors ; Gonadotropes ; Coated pits ; Internalization ; High-resolution autoradiography ; LHRH, Gonadoliberin ; Pituitary gland ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Localization of GnRH receptors in rat pituitary gonadotropes was studied by use of 125I-[azidobenzoyl-D-Lys6]GnRH which, upon photolysis, is covalently bound to the receptor molecule. Using high resolution autoradiography, it was found that, after a 90-min incubation of the analog with pituitary cells at 4° C, 93% of the silver grains were associated with the plasma membrane of the gonadotropes. After 45-min incubation of the cells at 37° C, clustering and internalization of the receptor-bound GnRH analog were evident. Silver grains were associated with coated pits, intracellular vesicles, Golgi complexes, lysosome-like structures and secretory granules. The data indicate that receptor-bound GnRH agonist is internalized, at least in part, via coated pits and is subsequently routed to lysosomes where degradation of the hormone-receptor complex may occur. The presence of a considerable amount of silver grains associated with secretory granules may suggest that some of the internalized receptor molecules can escape degradation and be recycled to the cell membrane.
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    URL: http://dx.doi.org/10.1007/BF00214895
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    Distribution pattern of drained antigens and antibodies in the subcapsular sinus of the lymph node of the rat (1985)
    Springer
    Cell & tissue research 239 (1985), S. 31-35 
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    ISSN: 1432-0878
    Keywords: Lymph filtration ; Antigen and antibody distribution ; Subcapsular sinus ; Lymph node ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A recent study of lymph nodes of the rat showed that they are morphologically and physiologically compartmentalized. A compartment of a node includes a portion of subcapsular sinus into which the lymph, entering via the related afferent lymphatic opening, is filtered. The study also showed that colloidal carbon injected locally in a small dose becomes predominantly associated with the areas of the inner wall of the subcapsular sinus that cover the extrafollicular zone of the peripheral cortex. Little carbon is seen over the folliculo-nodules (follicles with a nodule or germinal center). The question arose as to whether drained natural substances, as antigens and antibodies, follow the same pattern of distribution in the subcapsular sinus as the carbon. Therefore, small doses of fluorescein isothyocyanate (FITC)-conjugated antigens were injected locally into normal rats whose own antibodies in the nodes were stained by immunofluorescence. The pattern of distribution of the antigens in the draining nodes was found to be the same as that of the carbon. Furthermore, the lymph-carried antibodies of the rats were found to follow the same pattern. The morphological basis for such a pattern is explained. The results are further discussed with regard to the probable normal entry route of lymph-carried antigens in the parenchyma of nodes.
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    URL: http://dx.doi.org/10.1007/BF00214899
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    Evidence for tight junctions between odontoblasts in the rat incisor (1985)
    Springer
    Cell & tissue research 239 (1985), S. 137-140 
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    ISSN: 1432-0878
    Keywords: Lanthanum ; Odontoblasts ; Tight junctions ; Tooth pulp ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Odontoblasts are known to be involved in the process of dentinogenesis but it is not clear whether substances may also be deposited in predentine and dentine by passing between these cells. Although tight junctions have been described, it is not clear if they are macular or “leaky” as opposed to continuous or “tight”. In this study use has been made of the permeability of fenestrated capillaries amongst the odontoblasts to deposit the penetrative tracer lanthanum in the interodontoblastic space. This was done by perfusion of anaesthetized rats with physiological solutions containing lanthanum nitrate at 37° C. Immersion fixation of transverse segments of mandibular incisors and examination with an electron microscope showed that lanthanum could permeate 40–50 μm between the odontoblasts to reach the peripheral pulp. Towards the predentine, often less than 10 μm from the capillaries, its progress was abruptly and completely halted by the junctions at the apical ends of the odontoblast cell bodies. Lanthanum was not found in the predentine. The mature secretory odontoblasts in the rat incisor have therefore been shown to be joined by continuous tight junctions. In the process of dentinogenesis this means that all substances deposited in predentine and dentine must arrive by passing through the odontoblasts.
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    URL: http://dx.doi.org/10.1007/BF00214913
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    Fenestrations of the basal lamina of intestinal villi of the rat (1985)
    Springer
    Cell & tissue research 239 (1985), S. 183-188 
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    ISSN: 1432-0878
    Keywords: Fenestrations ; Basal lamina ; Intestine, small ; Immune system ; SEM ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fenestrations of the basal lamina of rat intestinal villi were revealed by scanning electron microscopy after removal of the overlying epithelial cells by osmic acid maceration. These fenestrations are circular to oval in shape and are 0.5 μm to 5 μm in diameter. They are richly distributed at a density of 1–2x104/mm2 in the upper two thirds of the villi, except at the very tips. Roughly 500 fenestrations are found on each side of an average sized tongue-shaped villus. Transmission electron-microscopic observations showed that these fenestrations were passages for migrating cells of the immune system such as lymphocytes, eosinophils and macrophages. Protrusions from the basal parts of epithelial cells were also observed passing through these fenestrations. These findings are discussed with respect to their immunological implications and to the passage of nutrients.
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    URL: http://dx.doi.org/10.1007/BF00214918
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    Fine structure of the lysosomes in the two types of synoviocytes of normal rat synovial membrane (1985)
    Springer
    Cell & tissue research 239 (1985), S. 293-298 
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    ISSN: 1432-0878
    Keywords: Acid phosphatase cytochemistry ; Lysosomes ; Synovial membrane ; Synoviocytes ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lysosomal system of the two types of synoviocytes (A and S) from the knee joint of normal rat synovial membrane was studied by electron-microscopic acid phosphatase cytochemistry. In random sections of the synovial intima lysosomes were more often encountered in the A-cell profiles than in the S-cell profiles. Characteristically, type-A synoviocytes showed many large and medium-sized lysosomes the cytochemical appearance of which varied considerably. No acid phosphatase activity was detectable in the cisternae of the Golgi apparatus or in the Golgi vesicles. In type-S synoviocytes the lysosomes were smaller, and more uniform in cytochemical appearance. Heavy deposits of acid phosphatase reaction product were constantly demonstrated in cisternae of the Golgi apparatus as well as in smooth-walled Golgi vesicles in type-S cells. The findings that type-A and type-S synoviocytes show distinctly different organization of the lysosomal system indicate that the roles of the lysosomes in these two types of cells may be different.
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    URL: http://dx.doi.org/10.1007/BF00218006
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    Increased gap junctional area in the rat liver after administration of dibutyryl cAMP (1985)
    Springer
    Cell & tissue research 239 (1985), S. 651-655 
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    ISSN: 1432-0878
    Keywords: Gap junctions ; cAMP ; Liver ; Freeze-fracturing ; Morphometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Since cAMP has recently been reported to be a possible physiological modulator of cell-to-cell communication, we performed a quantitative freeze-fracture investigation on the hepatocyte gap junctions after administration of a membrane-permeant derivative of this cyclic nucleotide. For this purpose, male rats received two intraperitoneal injections of 100 mg dibutyryl cAMP/kg body weight with a time interval of 2.5 h. Litter mates were injected with saline only. Five hours after the start of the treatment, tissue blocks of the left lateral liver lobe were fixed by immersion and processed for freeze-fracture. By point counting on negatives projected on a square double-lattice test system the relative gap junctional area on contiguous hepatocyte membranes was determined. As compared to control animals, the proportion of the membrane area occupied by gap junctions in dibutyryl cAMP-treated liver parenchyma significantly increased from 4.9% to 6.1%. Within the gap junctions no changes in shape, particle density or packing pattern were observed. Possibly, the enlarged gap junctional area provides structural pathways for the integration of the response of hepatocytes to messages mediated by cAMP.
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    URL: http://dx.doi.org/10.1007/BF00219244
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    Vascular permeability to lanthanum in the rat incisor pulp (1985)
    Springer
    Cell & tissue research 239 (1985), S. 131-136 
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    ISSN: 1432-0878
    Keywords: Capillary permeability ; Lanthanum ; Peripheral nerves ; Tooth pulp ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Experiments were performed to compare the permeability of capillaries supplying the endoneurial environment, which is invested by perineurium, with vascular permeability in the pulp where perineurium is absent. Anaesthetised rats were perfused through the aorta with physiological solutions containing lanthanum nitrate at 37° C. Pieces of inferior alveolar nerve and segments of mandibular incisors were immersion-fixed and transverse sections were examined electron microscopically for the distribution of lanthanum. In the pulp the nerve fibres pass between lanthanum-impermeable arterioles and venules en route to the incisal end. In the peripheral pulp a few capillaries were permeable but the most permeable capillaries lay between the odontoblasts. Pulpal capillary permeability was attributed to the fenestrated endothelium and contrasted with the unfenestrated endoneurial capillaries which were impermeable to lanthanum. Whereas the tight junctions of endoneurial capillaries are known to prevent certain blood-borne substances from entering the endoneurium, it was not clear whether the permeability of the pulpal capillaries, which are distant from the nerve fibres, could affect the nerve fibre environment. No extravasated lanthanum reached the pulpal nerve fibres suggesting that they are not affected. Technically it was not possible to examine the incisal third of the tooth where the situation could be different because the volume of the pulp decreases and capillaries lie closer to the nerve fibres.
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    URL: http://dx.doi.org/10.1007/BF00214912
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    Origin and distribution of neuropeptide Y-, vasoactive intestinal polypeptide- and substance P-containing nerve fibers in the urinary bladder of the rat (1985)
    Springer
    Cell & tissue research 239 (1985), S. 141-146 
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    ISSN: 1432-0878
    Keywords: Neuropeptides ; Autonomic denervation ; Neuropeptide Y ; Vasoactive intestinal polypeptide (VIP) ; Substance P ; Urinary bladder ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The origin and distribution in the urinary bladder of nerve fibers containing neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and substance P (SP) were investigated in rats. Experimental procedures comprised preganglionic decentralization or postganglionic denervation of the bladder and also chemical sympathectomy as well as capsaicin treatment of newborn rats. Nerve fibers containing NPY were richly distributed in the detrusor muscle and also in the pelvic ganglia. Numerous NPY-containing nerve cell bodies were found in pelvic ganglia. A rich occurrence of VIP fibers and a more sparse distribution of SP-containing fibers were also found in the bladder as well as a relatively rich representation of VIP- containing nerve cell bodies in the pelvic ganglia. After decentralization the intensity of VIP and NPY immunofluorescence increased in nerve cell bodies of the pelvic ganglia and in nerve fibers in the wall of the bladder. Postganglionic denervation, on the other hand, eliminated all peptides examined in the bladder wall. After postganglionic denervation the situation in the ganglia was approximately the same as after decentralization. Chemical sympathectomy (6-OHDA) did not seem to change significantly the frequency and distribution of VIP-, SP- and NPY-fibers in the muscle layer of the bladder or in the pelvic ganglia, while the NPY-containing nerve fibers in the submucosal layer and around blood vessels of the bladder disappeared. Adrenergic nerve fibers in the wall of the bladder (visualized by histofluorescence) were markedly reduced in number after administration of 6-OHDA. Capsaicin-treatment of newborn rats caused a loss of SP-fibers in the wall of the bladder, supporting the view that these fibers are sensory in nature in the urinary bladder. Although it cannot be entirely excluded that NPY-containing fibers in the wall of the bladder are adrenergic, the present results suggest that the NPY-fibers as well as the VIP-fibers of the bladder wall originate mainly in non-adrenergic cell bodies of the pelvic ganglia. However, perivascular NPY-containing nerve fibers are adrenergic in nature.
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    URL: http://dx.doi.org/10.1007/BF00214914
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    Non-lymphoid cells of bronchus-associated lymphoid tissue of the rat in situ and in suspension (1985)
    Springer
    Cell & tissue research 239 (1985), S. 177-182 
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    ISSN: 1432-0878
    Keywords: Lymphoid tissue ; Lung ; Bronchi ; Immuno-histochemistry ; Enzyme histochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunohistochemical, enzyme-histochemical and electron-microscopical methods were used to study non-lymphoid cells of control and stimulated rat bronchus associated lymphoid tissue (BALT) in situ and in suspensions. Particular attention was paid to the so-called antigenhandling cells, i.e., the interdigitating cells (IDC), which are situated in the T-cell areas, the follicular dendritic cells (FDC), which appear to be restricted to germinal centers, and macrophages, present both in T-cell and B-cell areas. The interdigitating cells were distinguished by being Ia-positive and by the presence of acid phosphatase and non-specific esterase activity in an area near the nucleus. Follicular dendritic cells could be observed in situ by using a monoclonal antibody and by the in vitro trapping of HRP-anti-HRP complexes. Several types of macrophages were found. At the electron-microscopical level no well-developed IDC and FDC could be detected in control BALT. However, in BALT of lipopolysaccharide-stimulated and mycoplasma-infected rats, well-developed IDC and FDC were found. It can be concluded that IDC's and FDC's can be found in BALT.
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    URL: http://dx.doi.org/10.1007/BF00214917
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    Stimulatory effect of follicle-stimulating hormone on rat Leydig cells (1985)
    Springer
    Cell & tissue research 239 (1985), S. 405-415 
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    ISSN: 1432-0878
    Keywords: Testis ; Leydig cell ; FSH ; Morphometry ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of FSH on the testicular interstitial tissue of immature hypophysectomized rats were studied by comparing morphological changes in Leydig cells with quantitative changes in interstitial tissue histology using morphometric analysis. Three groups of rats received subcutaneous injections of 0.5 ml saline vehicle or 10 μg rFSH or 20 ng oLH (equivalent to the amount of LH known to contaminate the FSH), twice daily for 7 days. Administration of FSH significantly increased testis weight and stimulated more advanced spermatogenesis compared to saline or LH. Morphometric analysis of testes of LH-treated rats showed a small but significant increase in total interstitial cell volume compared to saline treatment. FSH caused much greater increases in the total volume of interstitial tissue and interstitial cells than either saline or LH and significantly increased the total volume of interstitial fluid by comparison with the other groups. FSH but not saline or LH treatment resulted in a striking hypertrophy of Leydig cells, to produce cells ultrastructurally identical to Leydig cells from adults. Since the target tissue of FSH is the seminiferous epithelium, the observed effects on Leydig cells by FSH treatment suggest that the secretion of factors by the seminiferous tubules may mediate the maturation of Leydig cells.
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    URL: http://dx.doi.org/10.1007/BF00218021
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    Microthread-like filaments connecting the epithelial basal lamina with underlying fibrillar components of the connective tissue in the rat trachea (1985)
    Springer
    Cell & tissue research 239 (1985), S. 485-495 
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    ISSN: 1432-0878
    Keywords: Trachea ; Basal lamina ; Anchoring fibril ; Ruthenium red-positive filaments ; New anchoring device ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structural relationship between the basal lamina and the underlying reticular tissue was studied, with special attention to the relationship among basal lamina-associated anchoring fibrillar (AF) arcs (Kawanami et al. 1978, 1979) and other fibrillar components, in the epithelium-denuded trachea of the rat. Quantitative analysis of a large number of AF arcs reveals that the majority of the AF arcs has no other fibrillar components of passage. This suggests that most AF arcs do not serve as a real anchoring device, connecting the basal lamina with the underlying reticular tissue, as has so far been suggested by Kawanami et al. (1978). Ruthenium-red staining reveals the presence of a unique meshwork of microthread-like filaments connecting the undersurface of the basal lamina or the AF arcs with the underlying fibrillar components with a remarkable continuity, suggesting that the filaments act as a real anchoring device; these filaments link, instead of the AF arcs, the basal lamina, to the subjacent reticular tissue. Various enzymatic treatments of the filaments indicate that their chemical nature is probably non-collagenous (glyco)protein without glycosaminoglycan moieties.
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    URL: http://dx.doi.org/10.1007/BF00219226
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    Evidence for the existence of a subsinus layer of the peripheral cortex in the lymph node of the rat (1985)
    Springer
    Cell & tissue research 239 (1985), S. 37-42 
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    ISSN: 1432-0878
    Keywords: Subcapsular sinus ; Subsinus layer ; Peripheral cortex ; Lymph node ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The peripheral cortex of a lymph node consists of folliculo-nodules (follicles with a nodule or germinal center) and an extrafollicular zone. In the course of an analysis of the nodes in rats under various experimental or abnormal conditions, our attention became focused on the particularities of a thin layer of peripheral cortex underlying the subcapsular sinus. The present paper reports on observations which led to the identification of the “subsinus layer” of the peripheral cortex. The observations suggest that this layer complements the activity of the inner wall of the subcapsular sinus. The layer probably contributes to the selection of certain elements from the afferent lymph and guides them towards the node area where they can join the cell population involved in the immunological activity in which they are to participate.
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    Electrophoretic and cytological evidence for heterogeneity of pancreatic acinar cell responsiveness to carbachol, caerulein and secretin (1985)
    Springer
    Cell & tissue research 239 (1985), S. 105-109 
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    ISSN: 1432-0878
    Keywords: Pancreatic acini ; Secretion ; Amylase ; Secretagogues ; Receptors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Incubation of rat pancreatic lobules for 90 min with optimal concentrations of caerulein, carbachol or secretin caused the release of about 30% of the amylase content. Combination of secretin with carbachol or caerulein increased the amylase output to about 40%. With secretin, as with carbachol or caerulein, heterogeneity of cellular responsiveness was observed, some acini being partially or completely depleted of their zymogen granules, whereas others appeared to be resting. When secretin was combined with carbachol or caerulein, granule depletion, originally confined to small groups of neighbouring acini, spread to form large areas of degranulated cells, sometimes comprising a whole section of a lobule. In dispersed acini, under the same conditions, carbachol caused the release of about 60% of the amylase content, and secretin 40%. When both secretagogues were combined, a significant increase to 78% was observed. Under these conditions, there was some important cellular damage, as indicated by the release of 20% of the amylase content and between 6 and 12% of lactate dehydrogenase into the media, in the absence of stimulus. These results were corroborated by cytological observations. On the basis of their secretory response two groups of acini can be distinguished, those that respond to carbachol, caerulein or secretin and those that respond to the combination of secretin with carbachol or caerulein. Electrophoretic patterns of secretory proteins released by lobules stimulated by these different types of secretagogues were essentially similar. The pattern was quite different, however, in the absence of a stimulus. The most striking feature was the presence of a band at 63 Kd whereas a 73.5 Kd band was found only under conditions of stimulation. The latter results support the view that under resting and stimulated conditions secretory proteins are released from distinct compartments in the acinar cell.
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    Vincristine-induced abnormalities of gastrointestinal regulatory peptide cells of the rat (1985)
    Springer
    Cell & tissue research 239 (1985), S. 229-233 
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    ISSN: 1432-0878
    Keywords: Chemotherapy ; Vincristine ; Constipation ; Mucosa ; Regulatory peptides ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The microtubule-disrupting drug vincristine is a common component of anti-cancer chemotherapeutic regimes, which produces acute constipation as a side effect. Although generally attributed to damage to the myenteric plexus, the precise mechanism of this disturbance is unknown. In addition, vincristine causes marked aberrations in the secretory response of pancreatic endocrine tissue in both man and rats. No information is available on its possible effect on regulatory peptides of the gastrointestinal tract. In this study we have produced vincristine-induced constipation in rats at a dosage comparable with that employed in the treatment of human subjects. Immunocytochemistry revealed concomitant disturbances in cells exhibiting immunoreactivity for gastrin in the antrum, for gastric inhibitory polypeptide and 5-hydroxytryptamine in the duodenum, for enteroglucagon in the colon, and for somatostatin in all three sites. These widespread effects are transient in nature with normal cell numbers and morphology being reestablished within 6 days. It is suggested that the observed effects are a direct result of microtubule disruption and that gastrointestinal regulatory peptide and amine immunoreactive cells have a rapid regeneration potential.
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    Autophagy of mitochondria in rat bone marrow erythroid cells Relation to nuclear extrusion (1985)
    Springer
    Cell & tissue research 239 (1985), S. 235-239 
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    ISSN: 1432-0878
    Keywords: Erythropoiesis ; Autophagy ; Mitochondria ; Electron microscopy ; Stereology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Late erythroblasts and reticulocytes from bone marrow of male Wistar rats were studied by electron-microscopic stereology. Late erythroblasts with morphological signs of nuclear extrusion (EN+erythroblasts) and late erythroblasts without these signs (EN-erythroblasts) were analysed separately. The volumes of mitochondria, autophagosomes, autophagocytosed mitochondria, autophagocytosed cytoplasm and degraded material inside autophagosomes were calculated per unit volume of cytoplasm. The results demonstrate that (1) the volume density of mitochondria in the cytoplasm decreases by 34% during maturation from (EN-)- to (EN+)-erythroblasts (p〈 0.001) and by 60% during differentiation from (EN+)-erythroblasts to reticulocytes (p〈0.001), (2) a fivefold increase in the volume density of autophagosomes in the cytoplasm is noted during maturation from (EN-)- to (EN+)-erythroblasts (p〈0.01), whereas the value of this parameter remains essentially unchanged during the subsequent differentiation to reticulocytes, (3) no mitochondria are found inside autophagosomes of (EN-)-erythroblasts, whereas mitochondria occupy 26% and 35%, respectively, of the autophagosomal volume in (EN+)-erythroblasts and in reticulocytes. Our results show that autophagocytosis of mitochondria starts at the moment of nuclear extrusion and continues in the bone marrow reticulocytes.
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    URL: http://dx.doi.org/10.1007/BF00214924
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    Uptake of horseradish peroxidase by bone cells during endochondral bone development (1985)
    Springer
    Cell & tissue research 239 (1985), S. 547-553 
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    ISSN: 1432-0878
    Keywords: Endochondral bone development ; Osteoblast ; Osteoclast ; Horseradish peroxidase ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To investigate the mechanisms whereby bone cells absorb organic bone-matrix components during endochondral bone development, rat humeri were examined, employing horseradish peroxidase as a soluble protein tracer. Intravenously-injected peroxidase filled the osteoid layer and penetrated into the osteocyte lacunae and canaliculi, but did not enter the mineralized bone matrix. Whereas osteocytes rarely took up exogenous peroxidase, osteoblasts and osteoclasts actively endocytosed peroxidase in pinocytotic coated vesicles, tubular structures, and vacuoles. They also formed endocytotic vacuoles containing peroxidase in the Golgi area. The Golgi apparatus and dense bodies of these bone cells were, however, free of reaction products. Osteoclast ruffled borders were responsible for peroxidase absorption. In the osteoblast, osteocyte and osteoclast, endogenous peroxidatic reaction was detected only in mitochondria and not in other membrane-bounded vesicles and bodies. These results strongly suggest that both osteoblasts and osteoclasts participate in the resorption of bone-matrix organic components during bone remodelling.
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    Thyroidectomy induces coated pit formation on cerebellar mossy fiber terminals (1985)
    Springer
    Cell & tissue research 239 (1985), S. 627-631 
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    ISSN: 1432-0878
    Keywords: Thyroidectomy ; Cerebellum ; Coated pit ; Mossy fiber terminal ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The influence that thyroid hormones have on the development of the cerebellar cortex is well known. Their absence in adults leads to important functional changes probably related to abnormalities in nerve terminal activity, although no morphological alterations have hitherto been described. Using ultrastructural morphometric methods, we have studied the effects of thyroidectomy on the cerebellar cortex mossy fiber terminals of adult rats with different survival periods. No significant changes in the volume and surface area of these terminals were found. The numbers of synaptic vesicles in groups 7, 15 and 30 days after thyroidectomy were significantly greater than in controls. A significant increase in coated pit formation was found when thyroidectomized groups were compared with controls. This increase is due to the lack of thyroxin since it can be counteracted by thyroxin administration. Whether this increased coated pit formation is a membrane retrieval mechanism or is related to the uptake of extracellular molecules remains to be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219241
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  • 88
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    Neuroendocrine cells within colorectal tumours induced by dimethylhydrazine (1986)
    Springer
    Cell & tissue research 246 (1986), S. 205-210 
    Details
    ISSN: 1432-0878
    Keywords: 1,2-Dimethylhydrazine ; Peptide YY ; Glucagon ; 5-Hydroxytryptamine ; Immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Colorectal adenocarcinomas were induced in male Wistar rats, by weekly subcutaneous administration of 1,2-dimethylhydrazine, classified according to the degree of differentiation and submitted to immunocytochemistry for the peptides cholecystokinin (CCK), gastrin, gastric inhibitory polypeptide (GIP), glucagon, neurotensin, pancreatic polypeptide (PP), peptide YY (PYY), somatostatin and vasoactive intestinal polypeptide (VIP) and the biogenic monoamine 5-hydroxytryptamine. Well- or moderately well-differentiated adenocarcinomas comprised 46% of the tumour population, only 4% were poorly-differentiated adenocarcinomas, and the remaining 50% possessed a mixture of these two morphologies. Glucagon, PYY and 5-hydroxytryptamine immunoreactive cells were frequently observed within well- or moderately well-differentiated tumours and within such regions of tumours possessing a mixed morphological pattern. The tumours contained no cells immunoreactive for any of the peptides not normally located within the colorectum, nor did they contain cells immunoreactive for somatostatin and VIP, although known positive controls did stain. Poorly-differentiated tumours and portions of tumours of mixed type, were consistently negative. 5-hydroxytryptamine was the most frequently located of the three antigens, being detected in 87% of the moderately well-differentiated tumours and 32% of the tumours with mixed morphologies. 11% of moderately well-differentiated tumours possessed 5-hydroxytryptamine positive cells in such profusion that they contributed significantly to the tumour mass. The distribution of glucagon-and PYY-immunoreactive cells was similar, although they occurred with a lower frequency, presumably corresponding to their lower numbers within the normal colorectal mucosa. Additionally, these two peptide immunoreactivities were colocalized in the majority of cells, although some cells contained only one antigen. The immense numbers of cells immunoreactive for peptides and monoamine in a significant proportion of colorectal adenocarcinomas suggests that they have arisen from multipotential endodermal stem cells within the tumours and are not part of the normal epithelial population being engulfed as the tumour grows.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219019
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  • 89
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    Effect of brief vascular perfusion on the ultrastructure and activity of mitochondria isolated from the rat heart (1985)
    Springer
    Cell & tissue research 240 (1985), S. 247-249 
    Details
    ISSN: 1432-0878
    Keywords: Heart ; Mitochondria ; Perfusion ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Mitochondria isolated from heart tissue after a 1-min perfusion with Hanks medium were found to have significantly lower rates of State-3 respiration and respiratory control ratios compared to mitochondria isolated from non-perfused hearts. Examination of the mitochondrial preparations by electron microscopy revealed that a large proportion of the mitochondria isolated from perfused heart tissue were swollen and broken compared to mitochondria from non-perfused hearts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217581
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  • 90
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    Immunological detection of a cysteine protease in the skin and other tissues (1985)
    Springer
    Cell & tissue research 240 (1985), S. 417-423 
    Details
    ISSN: 1432-0878
    Keywords: Cysteine protease ; Epidermal cells ; Antigen localization ; Cell differentiation ; Antigen distribution ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Monospecific antibody directed to cysteine protease of 2-day-old rat epidermis recently characterized as being different from the proteases previously reported was produced in rabbits. By immunofluorescence microscopy and immunoperoxidase staining with an avidin-biotin-peroxidase method the protease was found to be present in the epidermis of rodents of different ages as well as that of humans, but not in the dermis. The staining in germinative cells was more intense than in cells in the superficial layers. It appeared as irregular patches in the nuclei and stained more diffusely in the cytoplasm where small granular components, strongly stained, were identified. The staining patterns in granular cells showed accumulation of the antigen in a granular form. The morphology and distribution of granules resembled those of keratohyalin-like granules in the nucleus and dense homogenous deposits in the cytoplasm. In cornified cells the reaction product was localized by the plasma membrane where concentration of the dense homogenous deposits occurred, suggesting that the cysteine protease is one component of the unique and characteristic structure of differentiated keratinocytes. In addition, the cysteine protease antigen having the same molecular weight as the epidermal enzyme was detected in liver, kidney and lung indicating a wider tissue distribution of the protease. The significance of the protease in regulation of cellular functions remains to be investigated.
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    URL: http://dx.doi.org/10.1007/BF00222354
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  • 91
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    The effect of reserpine on the pars intermedia of the rat pituitary (1985)
    Springer
    Cell & tissue research 241 (1985), S. 1-8 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary gland, pars intermedia ; Reserpine ; Secretory granules ; α-MSH ; β-Endorphin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Reserpine has a stimulatory effect on the pars intermedia of the rat pituitary, probably mediated by its action on regulatory catecholaminergic nerves. The effect of single intraperitoneal injections of 0.1–20 mg/kg b.w. of reserpine was studied in adult male rats. Reserpine at a dose of 2 mg/kg b.w. induced degranulation, orientation of the secretory granules along the cell membrane and loss of formaldehyde-chloral-induced fluorescence, accompanied by an activation of the granular endoplasmic reticulum and the Golgi apparatus. With higher doses progressive degranulation and loss of fluorescence were observed. The effect was, however, heterogeneous, and with all doses cells displaying normal ultrastructure and normal fluorescence were regularly present. To study the release of granular products (containing a different components of the pro-opiomelanocortin chain) from individual cells, formaldehyde-chloral induced fluorescence and α-MSH- and β-endorphin immunoreactivies were demonstrated in consecutive sections from pituitaries of rats given 8 mg/kg body weight of reserpine 24 h before sacrifice. The results indicate coordinated release of these granular products at the cellular level after reserpine treatment.
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    URL: http://dx.doi.org/10.1007/BF00214619
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  • 92
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    Arginine vasopressin causes morphological changes suggestive of fluid transport in rat choroid plexus epithelium (1986)
    Springer
    Cell & tissue research 246 (1986), S. 379-385 
    Details
    ISSN: 1432-0878
    Keywords: Arginine vasopressin ; Choroid plexus ; Fluid transport ; Cerebrospinal Fluid ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The experiments described herein use an in vitro preparation of choroid plexus to demonstrate that it is a vasopressin-responsive organ by morphologic criteria. Choroid plexus from rats was incubated for one hour in graded concentrations of arginine vasopressin (AVP). Within physiologic range of molar concentration, incubation in vasopressin induced a decrease in basal and lateral spaces in choroid plexus epithelial cells as well as an increase in number of dark cells. The number of cells with basal spaces decreased significantly from 82.7±9.2 in control tissue to 19±18 in tissue incubated in 10-12 M AVP; similarly, the number with lateral cellular spaces decreased from 20±8.8 to 7.6±2.2 cells in 10-10 M AVP. Dark cells increased in number from 3.8±2.6 in control conditions to 49±4 with 10-9 M vasopressin. These data suggest important effects of arginine vasopressin in cerebrospinal fluid (CSF) on choroid plexus, compatible with enhanced fluid transport across choroid epithelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215901
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  • 93
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    The effects of different steroids on costal and epiphyseal cartilage of fetal and adult rats (1986)
    Springer
    Cell & tissue research 246 (1986), S. 401-412 
    Details
    ISSN: 1432-0878
    Keywords: Glucocorticoids ; Cartilage ; Growth ; Histochemistry ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of different doses of various steroids on growth, and on costal and epiphyseal chondrocytes, have been studied in prenatal, immature, and adult Long-Evans rats using histochemical techniques, and both light and electron microscopy. Both prenatal and postnatal treatments have been employed. The steroids used were cortisone (CA), betamethasome (BM), and, in the prenatal group only, dexamethasone (DM). Body weight is reduced in all treated rats (except the low dose of CA) by day 17 of gestation, with greater weight reductions occurring in rats receiving the higher dose level of each steroid. In rats treated prenatally or neonatally, and sacrificed postnatally on days 39–43 or days 116–127, body weights, and tibial and tail lengths, are less than in correspondingly aged controls, thus showing a persistence of the effects of treatment. Costal and epiphyseal cartilages in prenatal rats show cellular, synthetic, and ultrastructural alterations induced by treatment with glucocorticoids but the responses are not necessarily comparable. Except for the low dose of DM, the higher doses of each steroid are more effective in inhibiting, or altering, growth and cellular differentiation in the developing fetuses. Surprisingly, a low dose of DM has a more devastating effect on the cells and extracellular matrix of both costal and epiphyseal cartilage, than do higher dose-levels of the various steroids. Low doses of CA and BM are also effective in inhibiting or altering growth and cellular differentiation, but their effectiveness is largely limited to 17 days of gestation. The order of effect of the various doses of the different steroids on fetal cartilage, listed in decreasing order of severity, is as follows: 0.12 DM, 0.24 DM, 0.42 BM, 50 CA, with 25 CA and 0.18 BM being approximately equal and only slightly different from control cartilages. The effect of prenatal or neonatal glucocorticoid treatment on chondrocytes is minimal in the 30–43 day, or 116–127 day, postnatal groups. In immature and adult rats, cortisone affects the chondrocytes more deleteriously than does betamethasone, and a 5.0 mg dose of CA seems to affect chondrocytes, body weight, and tibial and tail lengths more than 0.2 or 7.5 mg doses.
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    URL: http://dx.doi.org/10.1007/BF00215903
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    Distribution of endothelial vesicles in the microvasculature of skeletal muscle and brain cortex of the rat, as demonstrated by tannic acid tracer analysis (1986)
    Springer
    Cell & tissue research 246 (1986), S. 487-494 
    Details
    ISSN: 1432-0878
    Keywords: Microcirculation ; Endothelial vesicles ; Skeletal muscle ; Brain vessels ; Transendothelial transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrathin serial sectioning and labeling with tannic acid have demonstrated that most plasmalemmal vesicles of rat vascular endothelial cells are not free, but rather are conjoined in three dimensions to form racemose invaginations from the cell surfaces. To elucidate the distribution of vesicles in these microvascular endothelial cells, we have examined terminal arterioles, capillaries and post-capillary venules of rat skeletal muscle and brain cortex, using tannic acid labeling and stereological methods, and have determined the proportions of free vesicles and the vesicles of luminal and abluminal invaginations, as well as the numerical density of vesicles. In the case of capillaries, regional differences in distribution have also been studied. The ratio of free vesicles is 6–7% and is constant throughout the muscle microvasculature. The distribution (proportions and numerical densities) of vesicles in the brain and muscle microvascular endothelial cells shows regionally distinctive patterns. In rapid-frozen, freeze-substituted endothelial cells, there are almost as many fused vesicles as seen in chemically fixed cells. Therefore, aldehydes do not seem to induce membrane fusion, and the distribution of vesicles seems to be preserved by chemical fixation. The structure and function of plasmalemmal vesicles are discussed.
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    URL: http://dx.doi.org/10.1007/BF00215188
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  • 95
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    Uptake of released mast cell granules by reticular cells of the rat lymph node (1985)
    Springer
    Cell & tissue research 240 (1985), S. 49-55 
    Details
    ISSN: 1432-0878
    Keywords: Lymph node ; Reticular cell ; Mast cell granule ; Fibronectin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Granules released from mast cells were examined by electron microscopy in regional lymph nodes of rats after the injection of a large dose of horseradish peroxidase (HRP). Thirty minutes after the injection, a large number of mast-cell granules were present in sinuses, most of which adhered to the surfaces of reticular cells and some to macrophages. Two hours after the injection, a number of granules had been taken up by both reticular cells and macrophages. Reticular cells took up more granules than macrophages. Twenty-four hours after the injection, granules were scarce in both types of cells and in the extracellular space. Reticular cells surely participate in dealing with released mast-cell granules in the lymph node. Fibronectin bound to all mastcell granules was demonstrated by immunohistochemistry. Fibronectin probably enables negatively charged mast-cell granules to approach negatively charged cell surfaces to be taken up by both reticular cells and macrophages.
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    URL: http://dx.doi.org/10.1007/BF00217557
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  • 96
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    Immunohistochemical evidence for a magnocellular somatostatin cell group in the anterior paraventricular thalamus of the rat (1986)
    Springer
    Cell & tissue research 246 (1986), S. 683-685 
    Details
    ISSN: 1432-0878
    Keywords: Somatostatin (SRIF, GHR-IF) ; Neuropeptides ; Immunohistochemistry ; Thalamus ; Retrograde tracing ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By use of the indirect immunofluorescence technique a small group of large somatostatin-positive neurons is described in the subependymal area of the anterior paraventricular thalamus of the male rat. Retrograde-tracing experiments suggest that they project to areas outside the blood-brain barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215212
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  • 97
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    Analysis and in situ detection of cholecalcin messenger RNA (9000 Mr CaBP) in the uterus of the pregnant rat (1987)
    Springer
    Cell & tissue research 247 (1987), S. 51-57 
    Details
    ISSN: 1432-0878
    Keywords: Cholecalcin (vitamin D-dependent calcium-binding protein) ; mRNA ; Uterus ; In situ hybridisation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The molecular cloning of a cDNA fragment synthesised from rat duodenal mRNA coding for cholecalcin (calbindin), a 9000 Mr vitamin D-induced calcium-binding protein (CaBP), has been previously described. DNA/RNA hybridisation assays have been used to examine CaBP mRNA production in the uterine horns and duodena of pregnant (21 day) rats using the cloned CaBP cDNA. Northern hybridisation studies showed that the 32P cDNA sequence hybridised to a single 500–600 nucleotide species in both the uterus and the duodenum, thus demonstrating identical CaBP mRNA processing in both tissues. Dot blot hybridisation studies showed that the CaBP mRNA concentration was greatest in the duodenum while that of the uterine horns was about 10% of the duodenal level. The observed differences in CaBP mRNA levels correlate well with the in vivo CaBP concentrations. In situ hybridisation histochemistry using 3H cDNA revealed that CaBP mRNA visualised by silver grains was found in all the parts of the endometrium and the myometrium. However, CaBP mRNA was more concentrated in the outer and inner muscular fibres and in the luminal cells of the endometrium than in the stroma cells. These results demonstrate that the CaBP gene is expressed in specific cells of the rat uterus.
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    URL: http://dx.doi.org/10.1007/BF00216546
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  • 98
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    Stimulus-permeability coupling in rat pulmonary macrophages challenged by Pseudomonas aeruginosa (1985)
    Springer
    Cell & tissue research 240 (1985), S. 461-465 
    Details
    ISSN: 1432-0878
    Keywords: Macrophage activation ; Pseudomonas aeruginosa ; X-ray microanalysis ; Elemental analysis ; Electrolytes ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron probe X-ray microanalysis (XRMA) of freeze-dried ultrathin sections provides the capability of measuring intracellular elemental content. This methodology was used to investigate the stimulus-permeability coupling responses associated with phagocytosis of Pseudomonas aeruginosa by cultured pulmonary alveolar macrophages (PAMs) of rats. PAMs were challenged with P. aeruginosa suspended in Gey's buffer at a bacteria to PAM ratio of 50∶1 for 1 h at 37° C. A 1-mm3 pellet of the unchallenged control PAMs, challenged PAMs and P. aeruginosa alone was quench-frozen in nitrogen-cooled, liquid propane, and 0.1-μm cryosections were cut at -100° C. X-ray spectra were collected for nucleus and cytoplasm of 39 control PAMs, 36 challenged PAMs and 40 P. aeruginosa. Concentrations (mmole/kg dry weight) were obtained for Na, Cl, K, Ca, Mg, P, S for each cell. In the control PAMs, the content was similar to other mammalian cells. Moreover, there were no differences in elemental content between nucleus and cytoplasm. In the challenged PAMs, Na concentration was 4 times that of control PAMs (p〈0.001) whereas Cl was double (p〈0.001), K was 29% lower (p〈0.001), and Ca was 4 times higher (p〈0.05). The elemental concentration profile in the P. aeruginosa was distinctly different from that of the PAMs: higher Na, Ca, Mg, but lower Cl and K values. These results demonstrate elemental content changes in cultured PAMs challenged with P. aeruginosa that indicate a stimulus-permeability response by membranes associated with the phagocytic process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222360
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  • 99
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    Mitotic activity of gonadotropes in the anterior pituitary of the castrated male rat (1985)
    Springer
    Cell & tissue research 240 (1985), S. 271-276 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary ; Castration ; Gonadotropes ; Mitosis ; Testosterone replacement ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proliferation of gonadotropes in the anterior pituitary of the castrated male rat was examined immunohistochemically after colchicine treatment. The results show a more than 10-fold increase in mitotic frequency in gonadotropes 1 or 2 weeks after castration, as compared with controls. This result explains the increase in the population of immunoreactive LH cells in castrated male rats. The gonadotropes decreased significantly 1 month after castration. The mitotic activity of gonadotropes was almost completely suppressed in castrates implanted with a silastic tube filled with testosterone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222334
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  • 100
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    Survival of dissociated adrenal chromaffin cells of rat and monkey transplanted into rat brain (1985)
    Springer
    Cell & tissue research 240 (1985), S. 281-285 
    Details
    ISSN: 1432-0878
    Keywords: Cell dissociation ; Chromaffin cells ; Adrenal medulla ; Tissue transplantation ; Brain grafts ; Rat ; Marmoset monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Adrenal chromaffin cells from adult rats and monkeys were mechanically dissociated and implanted into the striatum of adult rats by stereotaxic injection. Rat chromaffin cells survived (5%) and showed differentiation by forming processes 1 h-28 days after implantation. Monkey chromaffin cells survived for 48 h but showed very little formation of processes. The method presented allows rapid nonenzymatic dissociation and transplantation of adrenal medullary cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222336
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