The contributions of nitrate uptake and efflux to isotope fractionation during algal nitrate assimilation

2014 ◽  
Vol 132 ◽  
pp. 391-412 ◽  
Author(s):  
K.L. Karsh ◽  
T.W. Trull ◽  
D.M. Sigman ◽  
P.A. Thompson ◽  
J. Granger
Keyword(s):  
Isotope Fractionation ◽  
Nitrate Uptake ◽  
Nitrate Assimilation

scholarly journals Molecular Components of Nitrate and Nitrite Efflux in Yeast

2013 ◽  
Vol 13 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Elisa Cabrera ◽  
Rafaela González-Montelongo ◽  
Teresa Giraldez ◽  
Diego Alvarez de la Rosa ◽  
José M. Siverio
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Uptake ◽  
Reductase Activity ◽  
Hansenula Polymorpha ◽  
Nitrate Assimilation ◽  
Nitrate Reductase Gene ◽  
Content Type ◽  
Nitrite Toxicity ◽  
Essential Components ◽  
Nitrate And Nitrite

ABSTRACTSome eukaryotes, such as plant and fungi, are capable of utilizing nitrate as the sole nitrogen source. Once transported into the cell, nitrate is reduced to ammonium by the consecutive action of nitrate and nitrite reductase. How nitrate assimilation is balanced with nitrate and nitrite efflux is unknown, as are the proteins involved. The nitrate assimilatory yeastHansenula polymorphawas used as a model to dissect these efflux systems. We identified the sulfite transporters Ssu1 and Ssu2 as effective nitrate exporters, Ssu2 being quantitatively more important, and we characterize the Nar1 protein as a nitrate/nitrite exporter. The use of strains lacking eitherSSU2orNAR1along with the nitrate reductase geneYNR1showed that nitrate reductase activity is not required for net nitrate uptake. Growth test experiments indicated that Ssu2 and Nar1 exporters allow yeast to cope with nitrite toxicity. We also have shown that the well-knownSaccharomyces cerevisiaesulfite efflux permease Ssu1 is also able to excrete nitrite and nitrate. These results characterize for the first time essential components of the nitrate/nitrite efflux system and their impact on net nitrate uptake and its regulation.

Differential contribution of arbuscular mycorrhizal fungi to plant nitrate uptake (15N) under increasing N supply to the soil

2001 ◽  
Vol 79 (10) ◽  
pp. 1175-1180 ◽  
Author(s):  
R Azcón ◽  
J M Ruiz-Lozano ◽  
R Rodríguez
Keyword(s):  
Mycorrhizal Fungi ◽  
Nitrate Uptake ◽  
Glomus Mosseae ◽  
Arbuscular Mycorrhizae ◽  
Nitrogen Nutrition ◽  
Nitrate Assimilation ◽  
Growth Period ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mycorrhizal Symbiosis

The objective of this study was to determine how the uptake and transport of nitrate by two species of arbuscular mycorrhizal (AM) fungi is affected by its concentration in the medium and by the age of the AM symbiosis. Tracer amounts of15N nitrate were applied at two plant growth periods to mycorrhizal or nonmycorrhizal lettuce plants, which had been grown in soil supplied with nitrate to provide a total of 84, 168, or 252 mg N/kg. At both injection times, Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe and Glomus fasciculatum (Thaxter sensu Gerd.) Gerd. and Trappe reached the highest values of nitrogen derived from the fertilizer (NdfF) at 84 mg N/kg. Glomus mosseae also reached the highest values of labeled fertilizer N utilization at 84 mg N/kg, whereas G. fasciculatum reached the highest values at 168 mg N/kg in the medium. The highest N level in the medium (252 mg N/kg) had a negative effect on % NdfF and % labeled fertilizer utilization for all mycorrhizal plants. Regarding the time of15N fertilizer application, G. fasciculatum-colonized plants had a minimum change in % NdfF and % labeled fertilizer utilization during the growth period (60 days application vs. 30 days application). In contrast, G. mosseae-colonized plants growing at 168 mg N/kg in the medium, decreased these two values in the latest application. The present results confirm that mycorrhizal symbiosis may be particularly important for nitrogen nutrition in plants growing in neutral-alkaline soils.Key words: arbuscular mycorrhizae, nitrate assimilation, nitrate uptake,15N-labeled fertilizer.

Inorganic nitrogen uptake by symbiotic marine cnidarians: a critical review

1989 ◽  
Vol 237 (1286) ◽  
pp. 109-125 ◽  
Keyword(s):  
Nitrogen Uptake ◽  
Critical Review ◽  
Nitrate Uptake ◽  
Nitrogen Limitation ◽  
Inorganic Nitrogen ◽  
Algal Growth ◽  
Nitrate Assimilation ◽  
Phosphorus Limitation ◽  
Ammonium Uptake ◽  
Physiological Data

The physiological data support host involvement in net ammonium uptake by intact symbioses. The evidence for nitrate assimilation by intact symbioses is equivocal. The depletion-diffusion model can account for net ammonium uptake by intact symbioses, but is inadequate to account for phosphate or nitrate uptake by symbioses. There is no evidence for nitrogen limitation as the means by which the host regulates algal growth in symbiosis; phosphorus limitation appears to be more likely.

scholarly journals Improved Plant Nitrate Status Involves in Flowering Induction by Extended Photoperiod

2021 ◽  
Vol 12 ◽  
Author(s):  
Jia Yuan Ye ◽  
Wen Hao Tian ◽  
Miao Zhou ◽  
Qing Yang Zhu ◽  
Wen Xin Du ◽  
...  
Keyword(s):  
Nitrate Uptake ◽  
Floral Induction ◽  
Nitrate Assimilation ◽  
Early Flowering ◽  
Nitrate Transporter ◽  
Loss Of Function ◽  
Flowering Locus T ◽  
Plant Populations ◽  
Flowering Genes ◽  
Photoperiodic Flowering

The floral transition stage is pivotal for sustaining plant populations and is affected by several environmental factors, including photoperiod. However, the mechanisms underlying photoperiodic flowering responses are not fully understood. Herein, we have shown that exposure to an extended photoperiod effectively induced early flowering in Arabidopsis plants, at a range of different nitrate concentrations. However, these photoperiodic flowering responses were attenuated when the nitrate levels were suboptimal for flowering. An extended photoperiod also improved the root nitrate uptake of by NITRATE TRANSPORTER 1.1 (NRT1.1) and NITRATE TRANSPORTER 2.1 (NRT2.1), whereas the loss of function of NRT1.1/NRT2.1 in the nrt1.1-1/2.1-2 mutants suppressed the expression of the key flowering genes CONSTANS (CO) and FLOWERING LOCUS T (FT), and reduced the sensitivity of the photoperiodic flowering responses to elevated levels of nitrate. These results suggest that the upregulation of root nitrate uptake during extended photoperiods, contributed to the observed early flowering. The results also showed that the sensitivity of photoperiodic flowering responses to elevated levels of nitrate, were also reduced by either the replacement of nitrate with its assimilation intermediate product, ammonium, or by the dysfunction of the nitrate assimilation pathway. This indicates that nitrate serves as both a nutrient source for plant growth and as a signaling molecule for floral induction during extended photoperiods.

scholarly journals Nitrate uptake, xylem NO3- flux, and nitrate assimilation in cowpea exposed to salinity

2010 ◽  
Vol 41 (1) ◽  
Author(s):  
Rafael Magalhães Aragão ◽  
Joaquim Albenísio Gomes Silveira ◽  
Evandro Nascimento Silva ◽  
Ana Karla Moreira Lobo ◽  
Antônia Tathiana Batista Dutra
Keyword(s):  
Nitrate Uptake ◽  
Nitrate Assimilation

scholarly journals Nitrate Uptake by Roots as Regulated by Nitrate Assimilation in the Shoot of Castor Oil Plants

1980 ◽  
Vol 65 (2) ◽  
pp. 286-290 ◽  
Author(s):  
Ernest A. Kirkby ◽  
Michael J. Armstrong
Keyword(s):  
Castor Oil ◽  
Nitrate Uptake ◽  
Nitrate Assimilation

scholarly journals Posttranslational Regulation of Nitrate Assimilation in the Cyanobacterium Synechocystis sp. Strain PCC 6803

2005 ◽  
Vol 187 (2) ◽  
pp. 498-506 ◽  
Author(s):  
Masaki Kobayashi ◽  
Nobuyuki Takatani ◽  
Mari Tanigawa ◽  
Tatsuo Omata
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Uptake ◽  
Wild Type Strain ◽  
Phosphorylation Site ◽  
Nitrate Assimilation ◽  
Synechococcus Elongatus ◽  
Posttranslational Regulation ◽  
Nitrate And Nitrite ◽  
Pcc 7942 ◽  
Pcc 6803

ABSTRACT Posttranslational regulation of nitrate assimilation was studied in the cyanobacterium Synechocystis sp. strain PCC 6803. The ABC-type nitrate and nitrite bispecific transporter encoded by the nrtABCD genes was completely inhibited by ammonium as in Synechococcus elongatus strain PCC 7942. Nitrate reductase was insensitive to ammonium, while it is inhibited in the Synechococcus strain. Nitrite reductase was also insensitive to ammonium. The inhibition of nitrate and nitrite transport required the PII protein (glnB gene product) and the C-terminal domain of NrtC, one of the two ATP-binding subunits of the transporter, as in the Synechococcus strain. Mutants expressing the PII derivatives in which Ala or Glu is substituted for the conserved Ser49, which has been shown to be the phosphorylation site in the Synechococcus strain, showed ammonium-promoted inhibition of nitrate uptake like that of the wild-type strain. The S49A and S49E substitutions in GlnB did not affect the regulation of the nitrate and nitrite transporter in Synechococcus either. These results indicated that the presence or absence of negative electric charge at the 49th position does not affect the activity of the PII protein to regulate the cyanobacterial ABC-type nitrate and nitrite transporter according to the cellular nitrogen status. This finding suggested that the permanent inhibition of nitrate assimilation by an S49A derivative of PII, as was previously reported for Synechococcus elongatus strain PCC 7942, is likely to have resulted from inhibition of nitrate reductase rather than the nitrate and nitrite transporter.

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