Claim · model-written summary
Tonoplast malate influx did not saturate at high external malate concentrations.
- Taxon
- carrot
Daucus carotat0 - Treatment
- high external malate concentrationse0
- Outcome
- this influx does not saturatee0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingDirectionValueQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this influx does not saturate at high external malate concentrations”
t0“Carrot”
Title
The Kinetics of Bicarbonate and Malate Exchange in Carrot and Barley Root Cells
W. J. CRAM; G. G. LATIES Journal of Experimental Botany 1974. doi:10.1093/jxb/25.1.11
Other claims from this paper (14)
- Observation Two-exponential fits to the two radiocarbon-loss plots gave inconsistent half times and were judged invalid.
- Observation A three-component model fit both radiocarbon-loss plots with equal rate constants and theoretically related intercepts.
- Observation The first fitted rate constant was about 7 h−1 and was attributed to cellular bicarbonate and carbon dioxide.
- Observation The second fitted rate constant was 1.5 h−1 and was attributed to cytoplasmic malate.
- Observation The third fitted rate constant was below 0.1 h−1 and was attributed to vacuolar malate.
- Observation The radiocarbon-loss data permit calculation of bicarbonate and carbon dioxide influx across the plasmalemma.
- Observation The data permit calculation of malate influx across the tonoplast during accumulation of endogenous malate.
- Observation At 1 mM external malate, carrot tissue uptake was linear over time.
- Observation At 1 mM external malate, uptake appeared limited by and equal to plasmalemma influx.
- Association At higher external malate concentrations, carbon dioxide evolution saturated.
- Association At higher external malate concentrations, tissue accumulation continued to rise.
- Observation Net malate efflux was very small but measurable.
- Observation External malate, chloride, nitrate, and sulfate did not stimulate efflux of radiolabeled malate.
- Observation The authors infer an absence of plasmalemma systems exchanging internal malate for the tested anions.