Abstract
Regulation by the active form of phytochrome (P FR ) and the effect of Ca 2+ was examined with nitrate reductase (NR) in etiolated cucumber ( Cucumis sativus cv. Beilpuig). Nitrate reductase activity (NRA) was studied in excised cotyledons of cucumber seedlings grown in distilled water and in darkness for seven days at 24 ± 0.5°C. All experiments were performed in the dark and a dim green safelight was used during analyses. In etiolated cucumber cotyledons NRA was induced by nitrate and a brief irradiation (15 min) with red light (R) resulted in 62% increase in NRA. This effect was nullified when R was followed immediately by a brief (5 min) far‐red light (FR). NRA also showed a semidian (12 h) rhythmicity. Both P FR , and nitrate effects were age dependent. Calcium seemed to be involved since the phytochrome effect was only observed when calcium was supplied in the external solution. The effect of R on NRA depended on the period of calcium nitrate incubation. An external supply of calcium ionophore mimicked the effect of R and, if supplied to R‐irradiated cotyledons, produced a higher NR level than that caused by R alone. This suggested that intracellular free calcium was involved.
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Claims 10
Claim · model-written summary
Nitrate induced nitrate reductase activity in etiolated cucumber cotyledons.
- Taxon
- cucumber
Cucumis sativuse0 - Organ / stage
- cotyledonse0
- Treatment
- nitratee0
- Outcome
- NRAe0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In etiolated cucumber cotyledons NRA was induced by nitrate”
Claim · model-written summary
Fifteen minutes of red light increased nitrate reductase activity by 62%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a brief irradiation (15 min) with red light (R) resulted in 62% increase in NRA”
t0“cucumber”
Claim · model-written summary
Far-red light immediately after red light nullified the red-light effect.
- Taxon
- cucumberCucumis sativust0
- Treatment
- far‐red light (FR)e0
- Outcome
- This effecte0
- Direction
- nullifiede0
- Comparator
- Re0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This effect was nullified when R was followed immediately by a brief (5 min) far‐red light (FR).”
t0“cucumber”
Claim · model-written summary
Nitrate reductase activity showed a 12-hour rhythm.
- Taxon
- cucumberCucumis sativust0
- Outcome
- NRAe0
- Value
- 12 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NRA also showed a semidian (12 h) rhythmicity.”
t0“cucumber”
Claim · model-written summary
Phytochrome and nitrate effects depended on age.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- agee0
- Outcome
- P FR , and nitrate effectse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both P FR , and nitrate effects were age dependent.”
t0“cucumber”
Claim · model-written summary
The phytochrome effect appeared only with calcium supplied externally.
- Taxon
- cucumberCucumis sativust0
- Treatment
- calciume0
- Outcome
- phytochrome effecte0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the phytochrome effect was only observed when calcium was supplied in the external solution.”
t0“cucumber”
Claim · model-written summary
The red-light effect on nitrate reductase activity depended on calcium nitrate incubation duration.
- Taxon
- cucumberCucumis sativust0
- Treatment
- calcium nitrate incubatione0
- Outcome
- effect of R on NRAe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect of R on NRA depended on the period of calcium nitrate incubation.”
t0“cucumber”
Claim · model-written summary
Externally supplied calcium ionophore mimicked the red-light effect.
- Taxon
- cucumberCucumis sativust0
- Treatment
- calcium ionophoree0
- Outcome
- effect of Re0
- Comparator
- Re0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“An external supply of calcium ionophore mimicked the effect of R”
t0“cucumber”
Claim · model-written summary
Calcium ionophore with red light produced higher nitrate reductase level than red light alone.
- Taxon
- cucumberCucumis sativust0
- Treatment
- calcium ionophoree1
- Outcome
- NR levele0
- Direction
- highere0
- Comparator
- R alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“if supplied to R‐irradiated cotyledons, produced a higher NR level than that caused by R alone.”
e1“An external supply of calcium ionophore mimicked the effect of R”
t0“cucumber”
Claim · model-written summary
The authors inferred a role for intracellular free calcium.
- Taxon
- cucumberCucumis sativust0
- Compound
- intracellular free calciume0
- Outcome
- intracellular free calcium was involvede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This suggested that intracellular free calcium was involved.”
t0“cucumber”
The same questions in other papers
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- no effect
- negative
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See all 7 papers →nitrogen · physiology: enzyme activity · Cucumis sativus (cucumber)Positive and negative results
6 papers in the same direction as this paper · 3 in the opposite direction
- negative
- negative
- no effect
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See all 10 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.