Modeling the Effects of Diffusion Limitations on Nitrogen-15 Isotope Dilution Experiments with Soil Aggregates

2003 ◽  
Vol 67 (2) ◽  
pp. 677-677
Author(s):  
John B. Cliff ◽  
Peter J. Bottomley ◽  
Roy Haggerty ◽  
David D. Myrold
Keyword(s):  
Isotope Dilution ◽  
Soil Aggregates ◽  
Diffusion Limitations ◽  
Dilution Experiments

Modeling the Effects of Diffusion Limitations on Nitrogen-15 Isotope Dilution Experiments with Soil Aggregates

2002 ◽  
Vol 66 (6) ◽  
pp. 1868-1877 ◽  
Author(s):  
John B. Cliff ◽  
Peter J. Bottomley ◽  
Roy Haggerty ◽  
David D. Myrold
Keyword(s):  
Isotope Dilution ◽  
Soil Aggregates ◽  
Diffusion Limitations ◽  
Dilution Experiments

The use of the 15N isotope dilution technique to estimate the contribution of associated biological nitrogen fixation to the nitrogen nutrition of Paspalum notatum cv. batatais

1983 ◽  
Vol 29 (8) ◽  
pp. 1036-1045 ◽  
Author(s):  
Robert M. Boddey ◽  
Phillip M. Chalk ◽  
Reynaldo L. Victoria ◽  
Eiichi Matsui ◽  
Johanna Döbereiner
Keyword(s):  
Isotope Dilution ◽  
Nitrogen Nutrition ◽  
Control Plant ◽  
Paspalum Notatum ◽  
Dilution Technique ◽  
N Nutrition ◽  
Advantages And Disadvantages ◽  
Reduction Activity ◽  
Dilution Experiments ◽  
Biological Nitrogen

This paper reports the results of a field experiment to investigate the use of the 15N-dilution technique to measure the contribution of biological N2 fixation to the N nutrition of the batatais cultivar of Paspalum notatum. The pensacola cultivar of this grass supports little associated N2 fixation as evidenced by the low associated C2H2 reduction activity and was thus used as a nonfixing control plant. The grasses were grown in 60-cm diameter concrete cylinders sunk into the soil, and the effects of four different addition rates of labelled nitrogen (NH4)2SO4, were investigated. The data from seven harvests clearly demonstrated that there was a significant input of plant associated N2 fixation to the nutrition of the batatais cultivar amounting to approximately 20 kg N∙ha−1∙year−1. Problems associated with the conduct of such isotope dilution experiments are discussed including the importance of using nonfixing control plants of similar growth habit, the advantages and disadvantages of growing the plants in cylinders as opposed to field plots, and the various methods of application of labelled N fertilizer.

THE INCORPORATION OF α-GLYCEROPHOSPHATE-32P INTO THE LIPIDS OF RAT BRAIN PREPARATIONS: II. ON THE BIOSYNTHESIS OF MONOPHOSPHOINOSITIDE

1967 ◽  
Vol 45 (1) ◽  
pp. 63-70 ◽  
Author(s):  
F. Possmayer ◽  
K. P. Strickland
Keyword(s):  
Phosphatidic Acid ◽  
Rat Brain ◽  
Isotope Dilution ◽  
Time Course ◽  
Acid Formation ◽  
Dilution Experiments ◽  
Phosphatide Acid

Previous investigations conducted in this laboratory showed a number of differences in the cytosine nucleotide requirement for the incorporation of α-glycerophosphate (α-G32P) into the monophosphoinositide of rat brain preparations compared to the pathway described by Paulus and Kennedy, where α-glycerophosphate → phosphatide acid → CDP-diglyceride → monophosphoinositide, and CTP is specifically required. Experiments were carried out with rat brain preparations to determine the nature of the mechanism whereby CDP-choline is as effective as or more effective than CTP in stimulating the incorporation of α-G32P into monophosphoinositide. Isotope dilution experiments in which unlabeled phosphatidic acid and CDP-diglyceride were used, yielded results consistent with the view that both of these compounds are intermediates in the incorporation of a-G32P into monophosphoinositide stimulated by either CTP or CDP-choline. Time-course experiments where cytosine nucleotides were added either at the beginning or after 20 minutes produced a pattern of labeling which could be fitted into the above interpretation, provided that newly formed radioactive molecules of phosphatide acid could be used selectively and CTP in some way inhibits phosphatide acid formation or accumulation. The latter could account for the observation that monophosphoinositide becomes far more actively labeled than phosphatidic acid in the presence of added CTP.

scholarly journals Nitrogen Fixation by Paenibacillus Polymyxa WLY78 is Responsible for Cucumber Growth Promotion

2021 ◽  
Author(s):  
Shuang Liu ◽  
Qin Li ◽  
Yongbin Li ◽  
Tianyi Hao ◽  
Sanfeng Chen
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Gene Cluster ◽  
Isotope Dilution ◽  
Laser Scanning ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Confocal Laser ◽  
Greenhouse Experiments ◽  
Dilution Experiments

Abstract Aims To study nitrogen contribution to cucumber derived from nitrogen fixation of Paenibacillus polymyxa WLY78.Methods The nif gene cluster deletion mutant (ΔnifB-V) of P. polymyxa WLY78 is constructed by a homologous recombination method. The GFP-labeled ΔnifB-V mutant was used to inoculate cucumber and to study colonization by confocal laser scanning microscope. The effects of plant-growth promotion were investigated by greenhouse experiments. The nitrogen fixation contribution was estimated by 15N isotope dilution experiments. Results Deletion of nif gene cluster of P. polymyxa WLY78 resulted in complete loss of nitrogenase activity. Observation by laser confocal microscopy revealed ΔnifB-V mutant can effectively colonize cucumber root, stem and leaf tissues, like wild-type P. polymyxa WLY78. Greenhouse experiments showed that inoculation with P. polymyxa WLY78 can significantly enhance the lengths and dry weights of cucumber roots and shoots, but inoculation with ΔnifB-V mutant can not. 15N isotope dilution experiments showed that cucumber plants derive 25.93% nitrogen from nitrogen fixation performed by P. polymyxa WLY78, but the ΔnifB-V mutant nearly can not provide nitrogen for plant growth. Conclusions This present study demonstrates that nitrogen fixation performed by P. polymyxa WLY78 is responsible for cucumber growth promotion.

Has the mystery of the vanishing 15 N in isotope dilution experiments been resolved?

1985 ◽  
Vol 30 (2) ◽  
pp. 444-447 ◽  
Author(s):  
P. M. Gilbert ◽  
F. Lipschultz ◽  
J. J. McCarthy ◽  
M. A. Altabet
Keyword(s):  
Isotope Dilution ◽  
Dilution Experiments

Comparison of Paenibacillus polymyxa wild-type and Nif− mutant in colonization, plant-growth promotion and nitrogen fixation contribution

2021 ◽  
Author(s):  
Shuang Liu ◽  
Qin Li ◽  
Yongbin Li ◽  
Tianyi Hao ◽  
Haowei Zhang ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Isotope Dilution ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Paenibacillus Polymyxa ◽  
Confocal Laser ◽  
Wild Type ◽  
Greenhouse Experiments ◽  
Dilution Experiments

Abstract Aims This study aimed to compare the effect on colonization, plant-growth promotion and nitrogen fixation contribution by inoculation with Paenibacillus polymyxa wild-type and Nif−mutant. Methods Paenibacillus polymyxa wild-type and Nif− mutant was labeled with GFP and then the GFP-labeled bacteria were used to inoculate cucumber. The colonization patterns of P. polymyxa WLY78 in these plants were observed under the confocal laser scanning microscope. The effects of plant-growth promotion were investigated by greenhouse experiments. The nitrogen fixation contribution was estimated by 15N isotope dilution experiments. Results Observation by laser confocal microscopy revealed that both P. polymyxa WLY78 and ΔnifB-V mutant can effectively colonize cucumber root, stem and leaf tissues. Greenhouse experiments showed that inoculation with P. polymyxa WLY78 can significantly enhance the lengths and fresh wights of cucumber roots and shoots, but inoculation with ΔnifB-V mutant can not. 15N isotope dilution experiments showed that cucumber plants derive 25.93% nitrogen from nitrogen fixation performed by P. polymyxa WLY78, but the ΔnifB-V mutant nearly can not provide nitrogen for plant. Conclusions This present study demonstrates that nitrogen fixation plays an import role in promoting plant growth.

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