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  • Calcium  (8)
  • Rhizobium  (8)
  • Springer  (16)
  • Periodicals Archive Online (PAO)
  • 1980-1984  (14)
  • 1975-1979  (2)
  • 1984  (14)
  • 1979  (2)
Collection
Keywords
Publisher
  • Springer  (16)
  • Periodicals Archive Online (PAO)
Years
  • 1980-1984  (14)
  • 1975-1979  (2)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Denitrification of nitrate to nitrogen gas by washed cells ofRhizobium japonicum and by bacteroids fromGlycine max (1984)
    Springer
    Planta 161 (1984), S. 81-85 
    Details
    ISSN: 1432-2048
    Keywords: Bacteroid ; Glycine (bacteroids) ; Denitrification ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrate, nitrite and nitrous oxide were denitrified to N2 gas by washed cells ofRhizobium japonicum CC706 as well as by bacteroids prepared from root nodules ofGlycine max (L.) Merr. (CV. Clark 63). Radiolabelled N2 was produced from either K15NO3 or Na15NO2 by washed cells ofRh. japonicum CC705 grown with either nitrate only (5 mM) or nitrate (5 mM) plus glutamate (10 mM). Nitrogen gas was also produced from N2O. Similar results were obtained with bacteroids ofG. max. The stoichiometry for the utilization of15NO 3 - or15NO 2 - and the produciton of15N2 was 2:1 and for N2O utilization and N2 production it was 1:1. Some of the15N2 gas produced by denitrification of15NO 3 - in bacteroids was recycled via nitrogenase into cell nitrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00951463
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  • 2
    Electronic Resource
    Electronic Resource
    Tentacle contraction inDiscophrya collini: The effects of ionophore A23187 and ruthenium red on Ca2+-induced contraction and uptake of extracellular calcium (1984)
    Springer
    Protoplasma 122 (1984), S. 125-131 
    Details
    ISSN: 1615-6102
    Keywords: Calcium ; Contraction ; Discophrya ; Ionophore A23187 ; Ruthenium red ; Tentacles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The tentacles of the suctorian protozoonDiscophrya collini are stimulated to contract by externally applied Ca2+. The role of extracellular Ca2+ in tentacle contraction was studied by monitoring45Ca2+ uptake, using ionophore A23187 to facilitate membrane transport of calcium and ruthenium red (RR) as an inhibitor of transport. The degree of tentacle retraction was dependent upon external Ca2+ concentration and studies with45Ca2+ using scintillation counting indicated a linear relationship between external Ca2+ concentration and Ca2+ uptake. Uptake of Ca2+ was enhanced in the presence of the ionophore while RR caused little inhibition.45Ca2+ uptake was only partially inhibited by RR when cells were subjected to a Ca2+, ionophore and RR mixture. Grain counts from light microscope autoradiographs after treatment of cells with45Ca2+/ionophore,45Ca2+/RR or45Ca2+ alone showed heavy, light and intermediate labelling respectively. In all instances the grains were evenly distributed within the cell. These observations are interpreted as supporting the suggestion that the ionophore enhances both the uptake of extracellular Ca2+ and release of Ca2+from an internal source, while the RR could only partially prevent movement of Ca2+ through the plasma mebrane. A model is presented suggesting that tentacle retraction is mediated by cytosolic Ca2+ levels which are determined by the fluxing of Ca2+ across the plasma membrane and the membrane of elongate dense bodies which act as internal Ca2+ reservoirs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279445
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of weight loss on serum 1,25-(OH)2-vitamin D concentrations in adults: A preliminary report (1984)
    Springer
    Calcified tissue international 36 (1984), S. 139-144 
    Details
    ISSN: 1432-0827
    Keywords: 1,25(OH)2-vitamin D ; Weight loss ; Phosphate ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary During a review of 42 metabolic studies in healthy women and men we observed that serum 1,25-(OH)2-D concentrations were directly correlated to the observed daily changes in body weight (r=0.68;P〈0.001) and to caloric intake/kg/day (r=0.39;P=0.01). These relationships could not be accounted for by related and physiologically expected changes in serum Ca or iPTH concentrations. However, serum 1,25-(OH)2-D concentrations were observed to be inversely correlated to serum PO4 levels (r=−0.44;P=0.004). In addition, serum PO4 levels were inversely correlated to the daily changes in body weight (r=−0.40;P=0.009). Since dietary sodium intake averaged 142 mmol/day, it is unlikely that the observed changes in weight were the result of changes in salt and water balance. Thus it seems reasonable to speculate that serum 1,25-(OH)2-D concentrations may vary directly with energy balance, as reflected by changes in body weight. This effect may be mediated by alterations in PO4 metabolism. The accurate assessment of serum 1,25-(OH)2-D levels thus appears to require several measurements over time periods during which body weight is stable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405309
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  • 4
    Electronic Resource
    Electronic Resource
    Factors affecting parathyroid hormone-induced hypophosphatemia and32P specific activity in thyroparathyroidectomized rats (1979)
    Springer
    Calcified tissue international 27 (1979), S. 239-246 
    Details
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Calcium ; Plasma phosphate ; Bone phosphate ; Plasma32P ; Specific activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Plasma changes in calcium, phosphate, and their radionuclides were studied in thyroparathyroidectomized (TPTX) rats treated with parathyroid hormone (PTH) for 8 h, this treatment starting 10 h after injection of45Ca and32P. Prior to intravenous infusion or hourly injections of PTH (10 mU/g/h), rats were maintained in one of three ways: on an extended fast (24 h); on a partial fast (10 h); or provided with 10% glucose and 1% calcium lactate overnight as a substitution for solid food. The pattern of change for plasma calcium,45Ca, and45Ca specific activity (S.A.) produced by PTH was not affected by these dietary conditions. The changes in phosphate were as follows: During the experimental (8 h) period, the rate of loss of32P from plasma in control rats was proportional to the length of the fast. This suggests that32P was released into plasma during the experimental period proportional to the ready availability of soft tissue glucose. In rats on an extended fast, PTH was phosphaturic, hypophosphatemic, and increased the rate of loss of32P from plasma without affecting32P S.A. values. In rats fasted for only 10 h, PTH produced similar effects on plasma phosphate and plasma32P values, but also caused a significant fall in plasma32P S.A. After glucose and calcium lactate treatment, PTH-induced phosphaturia was temporarily lost and the marked hypophosphatemia was replaced with a slight hyperphosphatemia. Plasma32P values also rose slightly; therefore, no effect on32P S.A. was produced. It is concluded from these studies that as the result of the phosphaturia caused by PTH, the hypophosphatemia which is produced automatically changes the phosphate gradient between various body compartments, causing phosphate entry into plasma. The authors postulate that this phosphate entering plasma is withdrawn primarily from bone fluid and bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441192
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  • 5
    Electronic Resource
    Electronic Resource
    The calciuria of increased fixed acid production in humans: Evidence against a role for parathyroid hormone and 1,25(OH)2-vitamin D (1979)
    Springer
    Calcified tissue international 28 (1979), S. 233-238 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; PTH ; 1,25(OH)2D ; Acid ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We measured mineral and acid balances, serum iPTH, urinary cAMP/creatinine, and plasma concentrations of 25OHD and 1,25(OH)2D in 7 healthy adults during control conditions and during increased fixed acid production achieved either by the administration of NH4Cl (N=3) or by increased dietary protein intake (N=4). When acid production was increased, the subjects were in positive acid balance and negative Ca balance because of increased urinary Ca excretion. Serum iPTH fell slightly but urinary cAMP and the plasma levels of vitamin D metabolites did not change. We conclude that the accelerated skeletal and urinary losses of Ca that occur when fixed acid production is increased are not contributed to nor compensated for by the parathyroid-vitamin D endocrine systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441241
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  • 6
    Electronic Resource
    Electronic Resource
    Calcium distribution in freeze-dried enamel organ tissue during normal and altered enamel mineralization (1984)
    Springer
    Calcified tissue international 36 (1984), S. 596-603 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Ameloblasts ; X-ray microanalysis ; Transport ; Frozen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Energy dispersive X-ray microanalysis was applied to freeze-dried blocks of enamel organ tissue to determine levels of calcium in various celular regions. The tissue blocks were dissected free from adjacent forming enamel following injection of cobalt or fluoride ions, both of which temporarily inhibit enamel mineralization. In all control and experimental specimens there was an increasing gradient of calcium from the stratum intermedium cells to the distal ends of the ameloblasts. Calcium levels were significantly reduced near the distal ends of the ameloblasts following cobalt or fluoride injection as compared with controls. It is suggested that evidence of an intercellular buildup of calcium near the distal ends of the ameloblast supports a controlling function of these cells. The changes in calcium levels are correlated with alterations in mineralization known to occur in the adjacent enamel of the model systems employed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405373
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  • 7
    Electronic Resource
    Electronic Resource
    In vitro precocious accumulation of calcium and matrix vesicles formation in young cartilage cells: Specific effects of corticosteroids (1984)
    Springer
    Calcified tissue international 36 (1984), S. 702-710 
    Details
    ISSN: 1432-0827
    Keywords: Corticosteroids ; Cartilage ; Organ culture ; Calcium ; Matrix vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The present study examined the effects of various corticosteroid and noncorticosteroid hormones upon the ultrastructure of chondroprogenitor cells and chondroblasts in an organ-culture system of late fetal condylar cartilage. Corticosteroids, (triamcinolone acetonide, dexamethasone, corticosterone) at concentrations of 10−6–10−8M stimulated markedly a precocious formation of matrix vesicles by chondroblasts. This stimulation was accompanied by a significant accretion of calcium complexes intra- and extracellularly in both the chondroprogenitor cell population and chondroblastsin vitro, as well as in the newly induced matrix vesicles. Nonglucocorticoid steroids (progesterone, estradiol, testosterone, cortexolone) did not evoke similar effects. Progesterone and testosterone, however, seemed to adversely affect the ultrastructure of the cartilage cells, whereas estradiol appeared to have a favorable effect on the morphology of cultured condylar cartilage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405393
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of phosphorus supply on phosphate uptake and alkaline phosphatase activity in Rhizobia (1984)
    Springer
    Archives of microbiology 140 (1984), S. 281-286 
    Details
    ISSN: 1432-072X
    Keywords: Alkaline phosphatase ; Continuous culture ; Glycerol 1-phosphate uptake ; Phosphate exchange ; Phosphate uptake ; Rhizobium ; Snake bean bacteroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of P nutrition on phosphate uptake and alkaline phosphatase activity was studied in chemostat culture for four rhizobial and three bradyrhizobial species. Phosphate-limited cells took up phosphate 10- to 180-fold faster than phosphate-rich cells. The four fast-growing rhizobial strains contained high levels of alkaline phosphatase activity under P-limited conditions compared to the repressed levels found in P-rich cells; alkaline phosphatase activity could not be detected in three slow-growing rhizobial strains, regardless of their P-status. Glycerol 1-phosphate-uptake in the cowpea Rhizobium NGR234 was derepressed over 50-fold under P-limited conditions, and appeared to be co-regulated with phosphate uptake. The phosphate-uptake system appeared similar in all strains with apparent K m values ranging from 1.6 μM to 6.0 μM phosphate and maximum activities from 17.2 to 126 nmol · min-1 · (mg dry weight of cells)-1. Carbonyl cyanide m-chlorophenyl hydrazone strongly inhibited phosphate uptake in all strains and a number of other metabolic inhibitors also decreased phosphate uptake in the cowpea Rhizobium NGR234. The phosphate uptake system in all strains failed to catalyse exchange of 32P label in preloaded cells or efflux of phosphate. The results suggest a single, repressible, unidirectional and energy-dependent system for the transport of phosphate into rhizobia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454943
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  • 9
    Electronic Resource
    Electronic Resource
    A continuous culture study of the phosphorus nutrition of Rhizobium trifollii WU95, Rhizobium NGR234 and Bradyrhizobium CB756 (1984)
    Springer
    Archives of microbiology 140 (1984), S. 276-280 
    Details
    ISSN: 1432-072X
    Keywords: Alkaline phosphatase ; Continuous culture ; Growth yields ; Phosphate ; Phosphorus nutrition ; Polyphosphate ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract With continuous cultures in a fully defined minimal salts medium steady states were achieved at both limiting and non-limiting concentrations of phosphate in the inflowing medium for Rhizobium trifolii WU95, cowpea Rhizobium NGR234, and Bradyrhizobium CB756. Millimolar growth yields obtained from P-limited cultures varied over 2-fold from 3.2 g dry weight·(mmol P)-1 for WU95 to 5.3 g dry weight·(mmol P)-1 for CB756 and 7.2 g dry weight·(mmol P)-1 for NGR234. For both WU95 and NGR234 growth under P-excess conditions resulted in elevated levels of total biomass P and the storage compound polyphosphate, compared with P-limited cultures. However, P-limited cultures of these two strains still contained significant quantities of polyphosphate. The P-status for CB756 cultures did not affect either total biomass P or polyphosphate levels. Alkaline phosphatase was maximally derepressed in P-limited cultures of WU95 and NGR234. However, in CB756 alkaline phosphatase was not detected at significant levels regardless of its P supply. These data suggest that growth of rhizobia is controlled predominantly by the attainment of a critical internal P level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454942
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of phosphorus supply on periplasmic protein profiles in Rhizobia (1984)
    Springer
    Archives of microbiology 140 (1984), S. 287-290 
    Details
    ISSN: 1432-072X
    Keywords: Alkaline phosphatase ; Continuous culture ; Periplasmic proteins ; Phosphate uptake ; Phosphorus nutrition ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lysozyme/EDTA treatment of four fast-growing rhizobia released repeatable protein profiles after polyacrylamide slab gel electrophoresis. Similar treatment of slow-growing rhizobia failed to release such periplasmic proteins. For the four-fast-growing rhizobia, both P-repressible and P-inducible protein bands occurred. The only P-repressible protein identified was alkaline phosphatase, which showed strain differences in both electrophoretic mobility and activation by Mg2+. The derepression of the P-repressible periplasmic proteins in cowpea Rhizobium NGR234 correlated with derepression of both phosphate and glycerol 1-phosphate uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454944
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