Abstract
Abstract The effects of extracellular K + concentration ([K + ] o ) on the pH of cell sap, “bulk cytoplasm” and vacuole have been investigated in Elodea densa leaves under conditions of either low or high activity of the plasmalemma electrogenic H + pump. Cell sap pH was evaluated directly in the cell sap expressed after freezing and thawing. Cytoplasmic and vacuolar pH were calculated by the weak base and weak acid distribution method, DMO and benzylamine appearing to be a suitable acid and base, respectively, for this purpose in this material. When added to the basal medium (no rapidly permeating ions present), 5 mM K + induced an increase in intracellular pH, larger for the cell sap and the vacuole (about 0.2 units), and smaller but still significant for the cytoplasm (0.07 units). This alkalinizing effect of K + was thus associated with a significant decrease in the pH difference across the tonoplast. The alkalinizing effect of K + was markedly and synergistically enhanced by the presence of fusicoccin, a condition inducing a marked activation of H + extrusion and of K + uptake. The correlation between these effects of [K + ] o on intracellular pH and those on H + extrusion indicates that changes in extracellular K + concentration, and thus in K + influx, can influence cytoplasmic and vacuolar pH by modulating the rate of H + extrusion by the plasmalemma H + pump.
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Claims 6
Claim · model-written summary
DMO and benzylamine were suitable probes for cytoplasmic and vacuolar pH in Elodea.
- Taxon
- Elodea densa
Egeria densat0 - Outcome
- suitable acid and basee0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DMO and benzylamine appearing to be a suitable acid and base, respectively, for this purpose in this material.”
t0“Elodea densa”
Claim · model-written summary
5 mM K + raised cell sap and vacuolar pH by about 0.2 units.
- Taxon
- Elodea densaEgeria densat0
- Organ / stage
- cell sap and the vacuolee0
- Treatment
- 5 mM K +e0
- Outcome
- pHe0
- Direction
- increasee0
- Value
- about 0.2 unitse0
- Comparator
- basal mediume1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“5 mM K + induced an increase in intracellular pH, larger for the cell sap and the vacuole (about 0.2 units)”
e1“When added to the basal medium (no rapidly permeating ions present)”
t0“Elodea densa”
Claim · model-written summary
5 mM K + raised cytoplasmic pH by 0.07 units.
- Taxon
- Elodea densaEgeria densat0
- Organ / stage
- cytoplasme0
- Treatment
- 5 mM K +e1
- Outcome
- intracellular pHe1
- Direction
- increasee1
- Value
- 0.07 unitse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“smaller but still significant for the cytoplasm (0.07 units)”
e1“5 mM K + induced an increase in intracellular pH”
t0“Elodea densa”
Claim · model-written summary
K + alkalinization accompanied a significant decrease in the pH difference across the tonoplast.
- Taxon
- Elodea densaEgeria densat0
- Treatment
- K +e0
- Outcome
- pH difference across the tonoplaste0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This alkalinizing effect of K + was thus associated with a significant decrease in the pH difference across the tonoplast.”
t0“Elodea densa”
Claim · model-written summary
Fusicoccin synergistically enhanced the alkalinizing effect of K +.
- Taxon
- Elodea densaEgeria densat0
- Treatment
- fusicoccine0
- Outcome
- alkalinizing effect of K +e0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The alkalinizing effect of K + was markedly and synergistically enhanced by the presence of fusicoccin”
t0“Elodea densa”
Claim · model-written summary
Extracellular K + and K + influx may influence cytoplasmic and vacuolar pH by modulating H + extrusion.
- Taxon
- Elodea densaEgeria densat0
- Outcome
- cytoplasmic and vacuolar pHe0
- Qualifier
- modulating the rate of H + extrusion by the plasmalemma H + pumpe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in extracellular K + concentration, and thus in K + influx, can influence cytoplasmic and vacuolar pH by modulating the rate of H + extrusion by the plasmalemma H + pump.”
t0“Elodea densa”