Abstract
Abstract Dark‐induced aging of detached primary leaves of 11‐day‐old barley seedlings brings about a significant decline in the rates of ferricyanide [Fe(CN) 6 ] 3− reduction and photophosphorylations of isolated chloroplasts. Ferricyanide‐supported noncyclic photophosphorylation is somewhat more susceptible to leaf aging than phenazine methosulfate (PMS)‐supported cyclic phosphorylation. Non‐latent membrane‐bound adenosine triphosphatase (ATPase) and ribulosediphosphate carboxylase (RuDPCase) lose about half of their initial activities after 24 h, while during this period the electron transport and photophosphorylation activities are much less affected. Also, the loss of RuDPCase is almost complete, while chloroplasts still exhibit a significant level of [Fe(CN) 6 ] 3− reduction and photophosphorylations after 7 days of dark incubation. This would suggest that the enzymatic dark reactions are more sensitive to aging stress than the primary photochemical reactions of chloroplasts. Studies on the effect of divalent cations such as Mg 2+ and Ca 2+ on non‐latent ATPase activity revealed that the dark stressed aging of detached leaves brings about a time dependent alteration in the response of this enzyme to Mg 2+ , but not to Ca 2+ . The former showed inhibitory as well as stimulatory response, whereas the latter always caused the usual stimulation. Addition of kinetin (50 μ M ) ensured retention of [Fe(CN) 6 ] 3− reduction, photophosphorylations and RuDPCase activity in chloroplasts during leaf aging, but it failed to preserve the initial loss in the activity of the non‐activated membrane‐bound ATPase.
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Claims 10
Claim · model-written summary
Dark aging significantly reduced ferricyanide reduction in barley chloroplasts.
- Taxon
- barley
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Hordeum vulgaree0 - Outcome
- ferricyanide [Fe(CN) 6 ] 3− reductione0
- Direction
- declinee0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“11‐day‐old barley seedlings brings about a significant decline in the rates of ferricyanide [Fe(CN) 6 ] 3− reduction and photophosphorylations of isolated chloroplasts.”
Claim · model-written summary
Dark aging significantly reduced chloroplast photophosphorylation.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- photophosphorylationse0
- Direction
- declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“11‐day‐old barley seedlings brings about a significant decline in the rates of ferricyanide [Fe(CN) 6 ] 3− reduction and photophosphorylations of isolated chloroplasts.”
Claim · model-written summary
Noncyclic photophosphorylation was more susceptible to leaf aging than cyclic phosphorylation.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- noncyclic photophosphorylatione1
- Direction
- more susceptiblee1
- Comparator
- phenazine methosulfate (PMS)‐supported cyclic phosphorylatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“Ferricyanide‐supported noncyclic photophosphorylation is somewhat more susceptible to leaf aging than phenazine methosulfate (PMS)‐supported cyclic phosphorylation.”
Claim · model-written summary
ATPase activity fell to about half its initial value after 24 hours.
- Taxon
- barleyHordeum vulgaree0
- Gene
- adenosine triphosphatase (ATPase)e1
- Outcome
- adenosine triphosphatase (ATPase)e1
- Direction
- losee1
- Value
- about halfe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“Non‐latent membrane‐bound adenosine triphosphatase (ATPase) and ribulosediphosphate carboxylase (RuDPCase) lose about half of their initial activities after 24 h”
Claim · model-written summary
RuDPCase activity fell to about half its initial value after 24 hours.
- Taxon
- barleyHordeum vulgaree0
- Gene
- ribulosediphosphate carboxylase (RuDPCase)e1
- Outcome
- ribulosediphosphate carboxylase (RuDPCase)e1
- Direction
- losee1
- Value
- about halfe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“Non‐latent membrane‐bound adenosine triphosphatase (ATPase) and ribulosediphosphate carboxylase (RuDPCase) lose about half of their initial activities after 24 h”
Claim · model-written summary
RuDPCase loss was nearly complete after seven days while electron transport and photophosphorylation remained appreciable.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- loss of RuDPCasee1
- Direction
- almost completee1
- Qualifier
- after 7 days of dark incubatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“the loss of RuDPCase is almost complete, while chloroplasts still exhibit a significant level of [Fe(CN) 6 ] 3− reduction and photophosphorylations after 7 days of dark incubation.”
Claim · model-written summary
Dark aging changed ATPase response to magnesium over time.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- response of this enzyme to Mg 2+e1
- Qualifier
- time dependent alteratione1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“dark stressed aging of detached leaves brings about a time dependent alteration in the response of this enzyme to Mg 2+ , but not to Ca 2+ . The former showed inhibitory as well as stimulatory response, whereas the latter always caused the usual stimulation.”
Claim · model-written summary
Dark aging did not alter the stimulatory ATPase response to calcium.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- response of this enzyme to Mg 2+ , but not to Ca 2+e1
- Direction
- not to Ca 2+e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“dark stressed aging of detached leaves brings about a time dependent alteration in the response of this enzyme to Mg 2+ , but not to Ca 2+ . The former showed inhibitory as well as stimulatory response, whereas the latter always caused the usual stimulation.”
Claim · model-written summary
Kinetin preserved ferricyanide reduction, photophosphorylation and RuDPCase activity during leaf aging.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- kinetin (50 μ M )e1
- Outcome
- [Fe(CN) 6 ] 3− reduction, photophosphorylations and RuDPCase activitye1
- Direction
- retentione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“Addition of kinetin (50 μ M ) ensured retention of [Fe(CN) 6 ] 3− reduction, photophosphorylations and RuDPCase activity in chloroplasts during leaf aging”
Claim · model-written summary
Kinetin did not preserve initial membrane bound ATPase activity during leaf aging.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- kinetine2
- Outcome
- activity of the non‐activated membrane‐bound ATPasee1
- Direction
- failed to preservee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley seedlings”
e1“it failed to preserve the initial loss in the activity of the non‐activated membrane‐bound ATPase.”
e2“Addition of kinetin (50 μ M ) ensured retention”
The same questions in other papers
kinetin · physiology: enzyme activity · Hordeum vulgare (barley)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
kinetin · molecular: metabolites · Hordeum vulgare (barley)Positive and negative results
1 paper in the same direction as this paper · 4 in the opposite direction
- positive
- positive
- positive
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.