Abstract
Pea chloroplasts isolated in salt media show decreased rates of 2:6 dichlorophenolindophenol (DCPIP) and ferricyanide reduction when depleted of CO(2) at pH values below 7.5. The greatest effect of CO(2) was on uncoupled systems. The incorporation of 10(-2), 2 x 10(-2) and 4 x 10(-2)m sodium acetate into the reaction mixtures progressively increased the bicarbonate concentration required for half maximal rates of reduction of DCPIP. The reaction was saturated by bicarbonate concentrations of 1 to 4 x 10(-2)m. With both DCPIP and ferricyanide, the addition of bicarbonate to illuminated chloroplast systems depleted of CO(2) gave very rapid increases in the rates of reduction. Bicarbonate also stimulated oxygen uptake by the illuminated chloroplasts when added hydrogen acceptors had been reduced. There was no effect of bicarbonate on ferricyanide reduction at low light intensities, but with DCPIP reduction, the apparent magnitude of the effect was independent of light intensity. This suggests that DCPIP reacts with the chloroplast electron transport chain at a site nearer to a photochemical stage than does ferricyanide. It also suggests that CO(2) has at least 2 sites of action.
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Claims 10
Claim · model-written summary
CO2 depletion decreased DCPIP and ferricyanide reduction below pH 7.5.
- Taxon
- Pea
Lathyrus oleraceuse0 - Treatment
- depleted of CO(2)e0
- Outcome
- 2:6 dichlorophenolindophenol (DCPIP) and ferricyanide reductione0
- Direction
- decreasede0
- Qualifier
- pH values below 7.5e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pea chloroplasts isolated in salt media show decreased rates of 2:6 dichlorophenolindophenol (DCPIP) and ferricyanide reduction when depleted of CO(2) at pH values below 7.5.”
Claim · model-written summary
CO2 had its greatest effect in uncoupled chloroplast systems.
Not reportedTaxon
Verbatim
e0“The greatest effect of CO(2) was on uncoupled systems.”
Claim · model-written summary
Increasing sodium acetate raised bicarbonate concentration needed for half-maximal DCPIP reduction.
- Treatment
- 10(-2), 2 x 10(-2) and 4 x 10(-2)m sodium acetatee0
- Outcome
- bicarbonate concentration required for half maximal rates of reduction of DCPIPe0
- Direction
- increasede0
Not reportedTaxonComparator
Verbatim
e0“The incorporation of 10(-2), 2 x 10(-2) and 4 x 10(-2)m sodium acetate into the reaction mixtures progressively increased the bicarbonate concentration required for half maximal rates of reduction of DCPIP.”
Claim · model-written summary
Bicarbonate saturated the reaction at 1 to 4 x 10(-2)m.
Not reportedTaxon
Verbatim
e0“The reaction was saturated by bicarbonate concentrations of 1 to 4 x 10(-2)m.”
Claim · model-written summary
Bicarbonate rapidly increased DCPIP and ferricyanide reduction in illuminated, CO2-depleted chloroplasts.
- Treatment
- addition of bicarbonatee0
- Outcome
- rates of reductione0
- Direction
- increasese0
- Qualifier
- illuminated chloroplast systems depleted of CO(2)e0
Not reportedTaxonComparator
Verbatim
e0“With both DCPIP and ferricyanide, the addition of bicarbonate to illuminated chloroplast systems depleted of CO(2) gave very rapid increases in the rates of reduction.”
Claim · model-written summary
Bicarbonate stimulated oxygen uptake after added hydrogen acceptors were reduced.
- Treatment
- Bicarbonatee0
- Outcome
- oxygen uptakee0
- Direction
- stimulatede0
- Qualifier
- when added hydrogen acceptors had been reducede0
Not reportedTaxonComparator
Verbatim
e0“Bicarbonate also stimulated oxygen uptake by the illuminated chloroplasts when added hydrogen acceptors had been reduced.”
Claim · model-written summary
Bicarbonate did not affect ferricyanide reduction at low light.
- Treatment
- bicarbonatee0
- Outcome
- ferricyanide reductione0
- Direction
- no effecte0
- Qualifier
- low light intensitiese0
Not reportedTaxonComparator
Verbatim
e0“There was no effect of bicarbonate on ferricyanide reduction at low light intensities”
Claim · model-written summary
The apparent bicarbonate effect on DCPIP reduction was independent of light intensity.
Not reportedTaxon
Verbatim
e0“with DCPIP reduction, the apparent magnitude of the effect was independent of light intensity.”
Claim · model-written summary
The authors infer that DCPIP reacts nearer a photochemical stage than ferricyanide.
- Outcome
- chloroplast electron transport chaine0
- Qualifier
- nearer to a photochemical stage than does ferricyanidee0
Not reportedTaxon
Verbatim
e0“This suggests that DCPIP reacts with the chloroplast electron transport chain at a site nearer to a photochemical stage than does ferricyanide.”
Claim · model-written summary
The authors infer that CO2 has at least two sites of action.
Not reportedTaxon
Verbatim
e0“It also suggests that CO(2) has at least 2 sites of action.”
The same questions in other papers
co2 · molecular: metabolites · Lathyrus oleraceus (pea)Positive and negative results
2 papers in the same direction as this paper · 3 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.