Abstract
Abstract The uptake of nitrate by wildtype plants and chlorate‐resistant mutants of Arabidopsis thaliana (L.) Heynh. was studied by intermittent or continuous measurement of the nitrate concentration of the ambient solution. The uptake rate in the wildtype and the nitrate reductase‐less mutant B 25 showed a dual‐phase relation ship with concentration. Each phase showed Michaelis‐Menten kinetics although multiphasic patterns within each phase could not be excluded. A dual‐phase relationship was also found in the uptake mutant B I. Here, however, phase II did not follow Michaelis‐Menten kinetics and uptake rate of nitrate in the phase II concentration range was considerably lower in the B 1 mutant than in the wildtype. It is concluded that the mutation in B I has disturbed phase II of the nitrate uptake, without affecting phase I, which leads to the suggestion that uptake of nitrate in Arabidopsis is mediated by at least two independent uptake mechanisms. The nitrate uptake rate showed an optimum at pH 8, and it was not stimulated by the presence of calcium. Ammonium had different effects on nitrate uptake: a direct effect, when it was present during the uptake of nitrate, resulting in a release of nitrate and a reduced rate of uptake, and an indirect inhibitory effect, possibly caused by assimilation products of ammonium, which is most pronounced after growth on ammonium as the sole nitrogen source or in long‐lasting uptake experiments in the presence of ammonium. Chlorate also showed a multiple effect, an inhibiting one which proved to be competitive and, at very low concentrations of chlorate, a stimulating one. Evidence was obtained that chlorate and nitrate arc taken up by the same carrier.
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Claims 15
Claim · model-written summary
Wildtype and mutant B 25 nitrate uptake had a dual-phase concentration relationship.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianat0 - Material
- wildtype and the nitrate reductase‐less mutant B 25e0
- Outcome
- dual‐phase relation ship with concentratione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The uptake rate in the wildtype and the nitrate reductase‐less mutant B 25 showed a dual‐phase relation ship with concentration.”
t0“Arabidopsis thaliana”
Claim · model-written summary
Each wildtype and B 25 phase showed Michaelis-Menten kinetics.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- wildtype and the nitrate reductase‐less mutant B 25e1
- Outcome
- Michaelis‐Menten kineticse0
- Qualifier
- multiphasic patterns within each phase could not be excludede0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Each phase showed Michaelis‐Menten kinetics although multiphasic patterns within each phase could not be excluded.”
e1“wildtype and the nitrate reductase‐less mutant B 25”
t0“Arabidopsis thaliana”
Claim · model-written summary
Uptake mutant B I also showed a dual-phase relationship.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- uptake mutant B Ie0
- Outcome
- dual‐phase relationshipe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A dual‐phase relationship was also found in the uptake mutant B I.”
t0“Arabidopsis thaliana”
Claim · model-written summary
Phase II of mutant B I failed to follow Michaelis-Menten kinetics.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- uptake mutant B Ie1
- Outcome
- phase II did not follow Michaelis‐Menten kineticse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phase II did not follow Michaelis‐Menten kinetics”
e1“uptake mutant B I”
t0“Arabidopsis thaliana”
Claim · model-written summary
Mutant B 1 had considerably lower phase II nitrate uptake than wildtype.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- B 1 mutante0
- Outcome
- uptake rate of nitratee0
- Direction
- considerably lowere0
- Comparator
- wildtypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“uptake rate of nitrate in the phase II concentration range was considerably lower in the B 1 mutant than in the wildtype”
t0“Arabidopsis thaliana”
Claim · model-written summary
The authors inferred that mutation B I disrupted phase II without affecting phase I.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- B Ie0
- Outcome
- phase II of the nitrate uptakee0
- Qualifier
- without affecting phase Ie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the mutation in B I has disturbed phase II of the nitrate uptake, without affecting phase I”
t0“Arabidopsis thaliana”
Claim · model-written summary
The authors suggested at least two independent Arabidopsis nitrate uptake mechanisms.
- Taxon
- ArabidopsisArabidopsise0
- Outcome
- uptake of nitratee0
- Qualifier
- at least two independent uptake mechanismse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“uptake of nitrate in Arabidopsis is mediated by at least two independent uptake mechanisms”
Claim · model-written summary
Nitrate uptake rate had an optimum at pH 8.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- nitrate uptake ratee0
- Direction
- optimume0
- Value
- pH 8e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nitrate uptake rate showed an optimum at pH 8”
t0“Arabidopsis thaliana”
Claim · model-written summary
Calcium did not stimulate nitrate uptake rate.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- presence of calciume0
- Outcome
- nitrate uptake ratee1
- Direction
- not stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it was not stimulated by the presence of calcium”
e1“The nitrate uptake rate”
t0“Arabidopsis thaliana”
Claim · model-written summary
Ammonium present during nitrate uptake caused nitrate release.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- Ammoniume1
- Outcome
- release of nitratee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when it was present during the uptake of nitrate, resulting in a release of nitrate”
e1“Ammonium had different effects on nitrate uptake”
t0“Arabidopsis thaliana”
Claim · model-written summary
Ammonium present during uptake reduced nitrate uptake rate.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- Ammoniume1
- Outcome
- rate of uptakee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when it was present during the uptake of nitrate, resulting in a release of nitrate and a reduced rate of uptake”
e1“Ammonium had different effects on nitrate uptake”
t0“Arabidopsis thaliana”
Claim · model-written summary
Ammonium indirectly inhibited nitrate uptake, most strongly after ammonium-only growth or prolonged exposure.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- ammonium as the sole nitrogen sourcee0
- Outcome
- indirect inhibitory effecte0
- Direction
- inhibitorye0
- Qualifier
- possibly caused by assimilation products of ammoniume0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an indirect inhibitory effect, possibly caused by assimilation products of ammonium, which is most pronounced after growth on ammonium as the sole nitrogen source or in long‐lasting uptake experiments in the presence of ammonium”
t0“Arabidopsis thaliana”
Claim · model-written summary
Chlorate competitively inhibited nitrate uptake.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- Chloratee0
- Outcome
- inhibiting onee0
- Direction
- inhibitinge0
- Qualifier
- competitivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorate also showed a multiple effect, an inhibiting one which proved to be competitive”
t0“Arabidopsis thaliana”
Claim · model-written summary
Very low chlorate concentrations stimulated nitrate uptake.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- very low concentrations of chloratee0
- Outcome
- stimulating onee0
- Direction
- stimulatinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at very low concentrations of chlorate, a stimulating one”
t0“Arabidopsis thaliana”
Claim · model-written summary
Evidence indicated chlorate and nitrate use the same carrier.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- chlorate and nitrate arc taken upe0
- Qualifier
- same carriere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Evidence was obtained that chlorate and nitrate arc taken up by the same carrier.”
t0“Arabidopsis thaliana”
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2 papers more in this group
See all 6 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.