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  • 1
    Electronic Resource
    Electronic Resource
    Vascular anatomy of fabaceous nodules of determinate growth (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The vascular anatomy of nodules of 12 genera of tropical pasture and grain legumes of three tribes of the Fabaceae is described. Tracheary strands branch dichotomously and repeatedly from a root connection and generally terminate within sealed pockets of endodermis. Anastomosis of vascular strands at the nodule tip to form a complete xylem circuit was seen in three genera (Vigna, Glycine and Lablab). The functional significance of vascular structure is discussed in terms of pathways of solute movement between the infected cells and the root, and the permeability of the nodule cortex to gases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb02153.x
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  • 2
    Electronic Resource
    Electronic Resource
    Vascular transport and soybean nodule function: II. A role for phloem supply in product export (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The ureide content of soybean (Glycine max (L.) Merr.) nodules was unaffected by variations in the transpirational rate, while whole plant manipulations designed to decrease phloem supply to nodules resulted in lower rates of nitrogenase activity and an increase in the ureide content of the nodules. The rate of ureide export from the nodule was estimated from the exponential rate of decrease in the pool size of ureides in nodules, following exposure to an N2-free atmosphere (Ar:O2). Export was greatly reduced under treatments which reduced phloem supply to the nodule. A water budget for nodules suggested that the delivery of water to the nodule via mass flow in the phloem was comparable to that required for export of ureides from the nodule in the xylem from the nodule. Therefore, we suggest that xylem export from nodules is related to the phloem supply to the nodule rather than to the transpirational flux in the parent root. This suggestion is related to the reported decreases in nodule permeability to gases under conditions of phloem deprivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1989.tb01631.x
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  • 3
    Electronic Resource
    Electronic Resource
    Vascular transport and soybean nodule function: nodule xylem is a blind alley, not a throughway (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The only published consideration of product removal from the soybean root nodule hypothesizes that the peripheral xylem circuit of this determinate nodule structure is flushed by the transpiration stream. However, dyes fed to the transpiration stream through a cut root distal to the nodule do not enter the nodule, and the observed movement of radio-tracers from the root into the nodule can be explained by simple diffusion, Also, there are few xylem elements in the nodule, and these elements are of a small diameter, such that this path can not act as a functional loop of the root system. Further, in this study, nodule vascular strands were never observed to be continuous about the nodule, but were observed to end at the nodule tip in a loop within an intact, closed endodermal sac. Nodule vascular tissue was invested in a pericycle of at least three cell layers. These cells are suggested to be active in the loading of the xylem apoplast with ureides, such that the xylem of the nodule always operates in an export role. Nodule water requirements may be supplied via the phloem or the root cortex apoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1989.tb01955.x
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  • 4
    Electronic Resource
    Electronic Resource
    Vascular transport and soybean nodule function. III: Implications of a continual phloem supply of carbon and water (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 13 (1990), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. In soybean, stores of carbon within the leaf have been demonstrated to support nodule metabolism under both photosynthetic and non-photosynthetic conditions. Indeed, a net depletion of nodule starch is observed only under conditions of suboptimal rates of nodule metabolism. Therefore, maximal rates of nodule metabolism are associated with a continual supply of phloem sap to the nodule, delivering water, carbon and other solutes. A restriction of phloem supply to the nodule may result in changes in turgor between the apoplast of the export pathway and the symplast of the nodule. This change may cause the observed decrease in the permeability to gases and to the rate of product export from nodules deprived of a phloem supply. It is suggested that nodule metabolism is homeostatically regulated in terms of internal O2 levels by the delivery of phloem water and solutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1990.tb01979.x
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  • 5
    Electronic Resource
    Electronic Resource
    A reappraisal of nitrate inhibition of nitrogenase in A317, a nitrate reductase-deficient mutant of pea (Pisum sativum) (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 84 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Symbiotic plants of Pisum sativum L. cv. Juneau and its nitrate reductase-(EC 1. 6. 6. 1)-deficient mutant, A317, were exposed to nitrate for up to 8 days and assessed for nitrate assimilation, nitrogenase activity and nodule carbohydrate status. The mutant, A317, was not impaired in its ability to absorb nitrate over up to 8 days, but was leakier with respect to nitrate reduction ability than previously realized, as 63% of the nitrate absorbed by the plant over 8 days was assimilated (in contrast to 93% in the wild type). After 2 days exposure to 5 mM nitrate, nitrogenase (EC 1.18.2.1) activity was less affected in A317 (84% of initial) than in Juneau (46% of initial): nodule starch reserves were less depleted in A317 (70% of initial) than in Juneau (26% of initial). It was concluded that nitrate reduction is a major cause of nitrate inhibition of nodule activity, and that its effect may be mediated through a decrease in the availability of carbohydrate to the nodules. Longer term (〉 4 day) exposure of A317 plants to nitrate resulted in accumulation of nitrate in plant tissues, an associated necrosis of shoot tissue, a marked decrease in nodule starch content and a severe inhibition of nodule activity. This consideration of the effect of the duration of exposure to nitrate is used to resolve a discrepancy between previous reports on the sensitivity to nitrate of nitrogenase activity in nitrate reductase-deficient mutants of pea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb04666.x
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  • 6
    Electronic Resource
    Electronic Resource
    β-Adrenergic modulation in the heart (1988)
    Springer
    Pflügers Archiv 411 (1988), S. 232-234 
    Details
    ISSN: 1432-2013
    Keywords: Cardiac myocyte ; delaved rectifier potassium channel ; calcium channel ; β-receptor agonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The temperature-dependence of the actions of β-receptor agonists and adenylate cyclase stimulation on both calcium and delayed rectifier potassium channel ionic currents were examined in patch-clamped guinea pig ventricular myocytes. We report that temperature can separate the β-receptor mediated modulation of potassium and calcium channels. Receptor-mediated increases in the delayed rectifier potassium current, but not the calcium current were very temperature-dependent over the range of 19 to 32°C. At room temperature (19–22°C) the β-agonist isoproterenol produced a large enhancement of the calcium current but had no effect on the delayed rectifier current. In contrast, at warmer temperatures (28–32°C) both currents increased in the presence of the agonist. This temperature-sensitivity also existed for direct stimulation of adenylate cyclase by forskolin. Thus, cardiac calcium and potassium channels appear to be independently regulated during adrenergic stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582323
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  • 7
    Electronic Resource
    Electronic Resource
    Suppression of charge movement by calcium antagonists is not related to calcium channel block (1987)
    Springer
    Pflügers Archiv 409 (1987), S. 217-219 
    Details
    ISSN: 1432-2013
    Keywords: Calcium antagonist drugs ; calcium currents ; charge movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The calcium channel-inhibiting drugs nitrendipine and diltiazem represent two important classes of organic calcium antagonists. In the present study, the effect of these drugs on calcium currents and charge displacement currents in bullfrog semitendinosus muscle fibers was examined using a vaseline gap voltage clamp. Nitrendipine (10 μM) reduced the quantity of charge that moved both during the ON phase (QON) and the OFF phase (QOFF) of charge movement. This action appeared to be most selective for QON. However, at this same concentration, nitrendipine had no blocking action on inward calcium currents. In contrast to these findings, diltiazem blocked calcium currents in a concentration-dependent manner, while slightly increasing the quantity of charge moved during QON and QOFF. The enhancement of charge movement by diltiazem resulted from two actions. First, diltiazem shifted the voltage-dependence of charge movement to more negative potentials. Second, diltiazem increased the maximum amount of charge moved. (Supported by NIH NS 03178 and HL 07382.)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584775
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of nitrogen nutrition on xylem sap composition of Casuarinaceae (1984)
    Springer
    Plant and soil 81 (1984), S. 291-293 
    Details
    ISSN: 1573-5036
    Keywords: Casuarinaceae ; Citrulline ; Frankia ; Nitrogen ; Nutrition ; Xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The major nitrogenous compound in the xylem sap ofCasuarina equisetifolia is citrulline, irrespective of nitrogen nutrition (dinitrogen fixation, nitrate or ammonium). The detection of citrulline in non-nodulated Casuarina suggests that its formation is not confined to root nodules. This precludes the possibility of using the relative citrulline content of xylem sap for quantification of N2 fixation in Casuarina. The possibility exists, however, that the relative abundance of citrulline to other nitrogenous compounds (e.g. amides or nitrate) in the xylem sap could be used as an indicator of N2 fixation and should be evaluated further.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02197162
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization ofR. fredii QB1130, a strain effective on commercial soybean cultivars (1987)
    Springer
    Plant and soil 99 (1987), S. 441-446 
    Details
    ISSN: 1573-5036
    Keywords: Bradyrhizobium japonicum ; C3A fast-growing rhizobia ; Glycine max ; Rhizobium fredii ; B1130 ; USDA191
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two rhizobial strains (QB1130 and C3A) from northeast China were identified asRhizobium fredii on the basis of growth rate, media acidification and growth on a wide range of carbon substrates. The strains were shown to be distinct from USDA 191 on the basis of plasmid number and size. Bothnif and commonnod genes were located on the 295 kb plasmid of strains QB1130 and USDA 191, while onlynif genes were identified on this plasmid in C3A. When used to inoculate four commercial soybean (Glycine max) cultivars, one of the strains (C3A) was found to be ineffective, while the other (QB1130) was at least as effective as USDA 191, a strain ofR. fredii reported to be widely effective on North American cultivars of soybean. Further, QB1130 was capable of more effective nodulation of cowpea or the uncultivated soybean line, Peking, than either USDA 191 or the slow-growingBradyrhizobium japonicum USDA 16. Strain QB1130 should be useful for studies directed at improving symbiotic performance in soybean, or for studies of the comparative physiology and genetics of FG and SG strains on a single host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02370889
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