Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Nitrate and ammonium influxes in soybean (Glycine max) roots: direct comparison of 13N and 15N tracing (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We compared influxes and internal transport in soybean plants (Glycine max cv. Kingsoy) of labelled N from external solutions where either ammonium or nitrate was labelled with the stable isotope15N and the radioactive isotope13N. The objective was to see whether mass spectrometric determinations of tissue 15N content were sufficiently sensitive to measure influxes accurately over short time periods. Our findings were as follows. (1) There was a close quantitative correspondence between estimates of N influx of individual plants using 15N or 13N measurements with either NO3/− or NH4+ at 4 or 2 mol−3, respectively in the external solution. (2) Transport to the shoot of N from NO3 absorbed over a 5–15 min period could be monitored when the external NO3− concentration ranged from 0–05 to 4 mol m−3. NH4+ as the N source labelled shoot tissue more slowly, and estimates of the transport between root and shoot could be made only with 13N. (3) Influx of NO3− into root tissue could be measured by 15N enrichment after 5–10 min at concentrations approaching the probable KM of the high-affinity transport system. (4) There was some indication of isotope discrimination, especially with respect to the movement of labelled N to the shoot, when NO3− is the N source.For many purposes, 15N tracing can be used satisfactorily to estimate influxes of both NO3− and NH4+ in soybean roots. Use of the short-lived radio nuclide 13N remains the method of choice for more refined measurements of internal distribution and assimilation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00422.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Effects of genetic modification of nitrate reductase expression on 15NO3– uptake and reduction in Nicotiana plants (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 21 (1998), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The physiological consequences for NO3– utilization by the plant of underexpression and overexpression of nitrate reductase (NR) were investigated in nine transformants of Nicotiana tabacum and Nicotiana plumbaginifolia. The in vitro NR activities (NRAs) in both roots and leaves of low- and high-NR tobacco transformants ranged from 5–10% to 150–200%, respectively, of those measured in wild-type plants. The level of NR expression markedly affected the NO3– reduction efficiency in detached leaves and intact plants. In both species, 15NO3– reduction ranged from 15–45% of 15NO3– uptake in the low-NR plants, to 40–80% in the wild-type, and up to 95% in high-NR plants. In the high-NR genotypes, however, total 15NO3– assimilation was not significantly increased when compared with that in wild-type plants, because the higher 15NO3– reduction efficiency was offset by lower 15NO3– uptake by the roots. The inhibition of NO3– uptake appeared to be the result of negative feedback regulation of NO3– influx, and is interpreted as an adjustment of NO3– uptake to prevent excessive amino acid synthesis. In genotypes underexpressing NR, the low 15NO3– reduction efficiency also was generally associated with a decrease in net 15NO3– uptake as compared with the wild type. Thus, underexpression of NR resulted in an inhibition of reduced 15N synthesis in the plant, although the effect was much less pronounced than that expected from the very low NRAs. The restricted NO3– uptake in low-NR plants emphasizes the point that the products of NO3– assimilation are not the only factors responsible for down-regulation of the NO3– uptake system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00269.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Imaging and relative quantification of ^1^5n and ^1^4n by SIMS microscopy in plant samples
    Amsterdam : Elsevier
    Biology of the Cell 75 (1992), S. 266 
    Details
    ISSN: 0248-4900
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0248-4900(92)90180-9
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    ^1^4N and ^1^5N imaging by SIMS microscopy in soybean leaves
    Amsterdam : Elsevier
    Biology of the Cell 74 (1992), S. 143-146 
    Details
    ISSN: 0248-4900
    Keywords: SIMS ; cryotechniques ; nitrogen ; soybean leaf
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0248-4900(92)90020-2
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Nuclear microprobe analysis of ^1^4N and ^1^5N in soybean leaves
    Amsterdam : Elsevier
    Nuclear Inst. and Methods in Physics Research, B 82 (1993), S. 465-473 
    Details
    ISSN: 0168-583X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0168-583X(93)95997-J
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Critical evaluation of thein situ nitrate reductase assay (1989)
    Springer
    Plant and soil 120 (1989), S. 243-251 
    Details
    ISSN: 1573-5036
    Keywords: barley ; corn ; nitrate ; nitrate reductase ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Anin situ method, derived from anin vivo method, was used to determine nitrate reductase activity (NRA) in:i) excised barley and corn shoots and excised soybean leaves during a N-depletion experiment and; ii) roots and shoots of N-depleted barley and corn seedlings during induction of nitrate, reductase (NR). Nitrate reduction, calculated from thesein situ RNA measurements, was compared with estimates of each organ's nitrate reduction in light aerobic conditions from NO 3 − consumption and a15N model (Gojonet al., 1986b). Thein situ RNA of roots strongly underestimated their15NO 3 − reduction. In contrast, in barley and corn shoots and in the first trifoliolate leaves from 26-day-old, soybean, thein situ NRA assay gave a fair approximation of the true NO 3 − reduction rate (relative differences ranging from −14 to +32%). In young soybean leaves (from 20-day-old plants), however, thein situ NRA strongly underestimated the actual NO 3 − reduction. The physiological significance of thein situ NRA assay in shoots and roots, and its value for field studies are discussed from these results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02377074
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Root contribution to nitrate reduction in barley seedlings (Hordeum vulgare L.) (1986)
    Springer
    Plant and soil 91 (1986), S. 339-342 
    Details
    ISSN: 1573-5036
    Keywords: Hondeum Vulgare L. ; Nitrate Nitrate reductase ; 15Nitrogen Root
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The leaf and root nitrate reductase activities were measured in 7 day-old barley seedlings by anoxic nitrite accumulation in darkness, during 48h after the transfer from a N-starved medium to a 1.5 mM K15NO3 medium. Thisin situ nitrate reduction was compared with the15N incorporation in the reduced N fraction of the whole seedlings. The nitrate reduction integrated fromin situ measurements was lower than the reduced15N accumulation. The rootin situ nitrate reductase activity seemed to account for only the third of the real root nitrate reduction, which may have been responsible for the overall underestimation. This discrepancy was partly explained by the ability of the root to reduce nitrite in an anoxic environment. These results suggest that, after correction of thein situ estimation of the nitrate reduction. the roots contribute to about 50% of the total assimilation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02198119
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    In situ nitrate reductase activity as an indicator of nitrate availability (1987)
    Springer
    Plant and soil 102 (1987), S. 145-148 
    Details
    ISSN: 1573-5036
    Keywords: barley ; fertilizer ; nitrate ; nitrate reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of external nitrate concentration in the nutrient solution on nitrate reduction by 7-day-old barley seedlings was investigated using anin situ nitrate reductase activity (NRA) assay, performed with or without exogenous nitrate during the incubation. The difference between plus and minus nitrate NRA of the leaves related to plus nitrate NRA decreased with increasing nitrate concentration in the nutrient solution. Furthermore, the root contribution to the whole plant NRA became predominant at low external nitrate levels. It is proposed that plus and minus nitrate NRA should be used together as an indicator of nitrate availability in the medium and of root contribution to whole plant nitrate reduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02370917
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...