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  • 1
    Electronic Resource
    Electronic Resource
    Transportation system for 11CO2 (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 783-786 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A transportation system for safe movement of up to 1.0 Ci of 11CO2 from a production facility to an experimental facility 800 m away is described. This development allows plant physiological tracer kinetic studies to be performed in a remote laboratory location which is more suitable for plant growth. It also has the potential to allow field studies to be performed in nearby outdoor field plots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141019
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  • 2
    Electronic Resource
    Electronic Resource
    Automatic system for the control of batch-produced 11CO2 for continuous labeling experiments (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 467-469 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A system for storage and continuous dispensing of constant activity 11CO2 from batch production is described. The system has been used successfully to maintain constant activity levels for 2-h plant tracer kinetic experiments. This development now allows any existing cyclotron facility to supply a radioisotope stream continuously from a short batch irradiation. It requires no modification for use with other isotopes such as N-13 or O-15 in gaseous form and can be used in other biological and clinical investigations as well as the plant physiology investigations for which it was developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139862
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  • 3
    Electronic Resource
    Electronic Resource
    Physiological Roles of Ethylene in Plants (1969)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology 20 (1969), S. 541-584 
    Details
    ISSN: 0066-4294
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pp.20.060169.002545
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  • 4
    Electronic Resource
    Electronic Resource
    Consequences of insufficient equations in models of the Münch hypothesis of phloem transport (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 2 (1979), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The suggestion of concentration dependent unloading as a necessary assumption for a closed-form mathematical expression of the Münch hypothesis of phloem transport (Goeschl et at., 1976) has been recently questioned (Ferrier & Christy, 1977). Also questioned was whether previous models, known to have one less equation than dependent variables, have produced erroneous or misleading results. A review of Münch's original concepts and recent comments by several researchers indicate that an equation describing the exit of solutes from sieve tubes is essential for consistency with the Münch hypothesis. Evidence is presented to show that previous mathematical predictions and interpretations regarding ‘runaway velocities’ have resulted in part from mathematical inconsistencies and characteristics of the numerical solution procedures. Likewise, a proposal that different steady-state velocities and concentrations of transport at a given loading rate might be determined by ‘previous history’ of the system can be explained on the basis of implied relationships hidden in models with insufficient equations. Finally it is concluded that concentration dependent unloading in models of the Münch hypothesis will not detract, but rather will contribute to their usefulness in experimental testing and other research regarding phloem transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1979.tb00791.x
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  • 5
    Electronic Resource
    Electronic Resource
    Experimental tests of the Münch–Horwitz theory of phloem transport: effects of loading rates (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Extended square-wave tracer kinetics using 11CO2 were used to measure the speed of transport and activity level (proportional to concentration) in the phloem at high and low loading rates in six species of plants. In all cases, increased loading rates resulted in increased concentration. In most cases speed also increased, however, in two cases speed was lower and tracer activity was much higher at the higher loading rate. All the responses are consistent with the Münch Horwitz theory of phloem transport, depending upon the equation used to represent the unloading mechanism as described in a previous paper (Goeschl & Magnuson, 1986). For example, the latter two cases are consistent with the assumption that the unloading rate was limited by a process with saturable kinetics (enzyme-like).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1986.tb01572.x
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  • 6
    Electronic Resource
    Electronic Resource
    Spontaneous and induced blocking and unblocking of phloem transport (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 7 (1984), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Steady-state labelling with 11CO2 was used to observe the blocking of phloem transport, induced by chilling short regions of stems or petioles of velvetleaf (Abutilon theophrasti Medic.) or cotton (Gossipium hirsutum L.). The abruptness of these blockages was evidenced by sharp decreases in 11C activity below, and increases above a 2 to 3 cm region cooled from 28°C to 18 or 13°C for periods as short as 2 min. Abrupt unblocking of transport in velvetleaf occurred a few minutes after rewarming, as evidenced by a sharp rise and and overshoot in 11C activity. Recovery of transport in cotton was more prolonged and was marked by occasional spontaneous blocking and unblocking of transport at various points along the petiole or stem, not necessarily in the cooled region. Similar spontaneous events were often observed in undisturbed cotton plants, but only rarely in velvetleaf.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11592141
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  • 7
    Electronic Resource
    Electronic Resource
    Physiological implications of the Münch-Horwitz theory of phloem transport: effects of loading rates (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Predicted effects of phloem loading rates on the five profiles of unloading rate, osmotic water flux, pressure, transport speed and concentration, in hypothetical sieve tubes with different sink properties, were calculated using the steady-state mathematical expression of the Münch hypothesis of phloem transport. The prediction that increased loading rates always increases the concentration, and generally increase the speed of translocates through the sieve tube, is emphasized since these parameters are accessible for experimental testing. This particular prediction contrasts with a previous prediction (Tyree, Christy, & Ferrier, 1974), that where concentration was held constant at the loading end, concentration along the rest of the sieve tube would decrease, while speed would increase greatly.Where the unloading mechanism was assigned saturable (enzyme-like) kinetics, increased loading rates (in the range well below the Vmax of the sink) caused both transport speed and concentration to increase. However, as loading rates approached the Vmax of the sinks, speed reached a maximum and then declined, and concentration increased substantially. This was particularly true at very high values of Km, e.g. 〉 0.1 mol cm−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1986.tb01571.x
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  • 8
    Electronic Resource
    Electronic Resource
    Short-term responses of phloem transport to mechanical perturbation (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 72 (1988), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Jaeger, C. H., Goeschl, J. D., Magnuson, C. E., Fares, Y. and Strain, B. R. 1988. Short-term responses of phloem transport to mechanical perturbation. - Physiol. Plant. 72: 588–594.Phloem transport was monitored using a continuous stream of 11CO2-labelled air administered to one leaf while gamma detectors measured 11C activity at intervals along the stem. The effect of gentle, non-injurious mechanical perturbation on phloem transport was tested in cotton (Gossypium hirsutum L. cv. Stoneville 213). Mechanical stimuli such as shaking, localized vibration and gentle massage were applied while the plants were at isotope equilibrium. Localized phloem blockages were observed within 1–2 min of the stimuli. The blockages lasted from 6–55 min and full recovery of transport required 20–175 min. The effect of preconditioning to mechanical perturbation on phloem transport was tested in bush beans (Phaseolus vulgaris L. cv. Cherokee Bush). Preconditioning of a bean seedling to gentle stem massage resulted in a shorter blockage response and quicker transport recovery period when the seedling was massaged during a 11C tracer experiment compared to a control seedling. These results indicate that measurements of phloem transport on recently disturbed plants will probably show depressed phloem transport velocities. Measurements should be made after at least a 24-h disturbance-free recovery period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1988.tb09169.x
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  • 9
    Electronic Resource
    Electronic Resource
    An integrated tracer kinetics system for studying carbon uptake and allocation in plants using continuously produced11CO2 (1982)
    Springer
    Radiation and environmental biophysics 21 (1982), S. 51-65 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary An integrated approach to study the effects of environmental factors on plants is described. The central theme of the system is the use of CO2 labelled with11C supplied continuously to the plant and following the emitted radiation in vivo in the leaf, the phloem and the various sinks. The system consists of six components and with minor changes can be used for other tracers such as13N for nitrogen fixation studies. Because of the short half life of the isotope, several experiments can be carried out on the same plant under the same environmental conditions without disturbing the plant. A host of ecologically, agriculturally and genetically important questions can be answered using this technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01338755
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  • 10
    Electronic Resource
    Electronic Resource
    Low night temperature effect on photosynthate translocation of two C4 grasses (1985)
    Springer
    Oecologia 67 (1985), S. 305-309 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Translocation of assimilates in plants of Echinochloa crus-galli, from Quebec and Mississippi, and of Eleusine indica from Mississippi was monitored, before and after night chilling, using radioactive tracing with the short-life isotope 11C. Plants were grown at 28°/22°C (day/night temperatures) under either 350 or 675 μl·l-1 CO2. Low night temperature reduced translocation mainly by increasing the turn-over times of the export pool. E. crus-galli plants from Mississippi were the most susceptible to chilling; translocation being completely inhibited by exposure for one night to 7°C at 350 μl·l-1 CO2. Overall, plants from Quebec were the most tolerant to chilling-stress. For plants of all three populations, growth under CO2 enrichment resulted in higher 11C activity in the leaf phloem. High CO2 concentrations also seemed to buffer the transport system against chilling injuries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384934
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