Abstract
SUMMARY The effects of K, Ca, Mg and H ions on the kinetics of Cd uptake by the moss Rhytidiadelphus squarrosus (Hedw.) Warnst were investigated. The affinity of extracellular exchange sites for these ions decreased in the order Cd, H > Ca > Mg ≫ K and there were competitive interactions between ions. The affinity of the intracellular Cd transport site for these ions decreased in the order Ca > Cd > Mg ≫ K. Calcium was shown to be competitive and Mg a non‐competitive inhibitor of intracellular Cd uptake. Intracellular Cd uptake, optimal at about pH 5.6, was highly sensitive to pH, which primarily affected the V max . Potassium, supplied at less than 1 mM, had no significant effect on Cd uptake. However, at concentrations greater than 1 mM, KNO 3 caused both a stimulation in transport site activity and reduced affinity for Cd. Pretreatment with KNO 3 removed potentially competing ions from the cell wall, altering the subsequent chemical equilibria established when moss shoots were incubated in Cd solutions. Reduced competition from ions removed by KNO 3 pretreatment resulted in a higher affinity of both transport sites and extracellular exchange sites for Cd, Ca and Mg. The results demonstrate quantitatively the regulatory effects on intracellular metal uptake of the extracellular ionic environment provided by the cell wall.
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Claims 13
Claim · model-written summary
Extracellular exchange sites for ions decreased in affinity in the order Cd, H > Ca > Mg >> K.
- Taxon
- Rhytidiadelphus squarrosus
Rhytidiadelphus squarrosust0 - Outcome
- affinity of extracellular exchange sitese1
- Direction
- decreasede1
- Qualifier
- in the order Cd, H > Ca > Mg ≫ Ke1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e1“The affinity of extracellular exchange sites for these ions decreased in the order Cd, H > Ca > Mg ≫ K”
Claim · model-written summary
Ions showed competitive interactions for extracellular exchange sites in moss.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Outcome
- competitive interactions between ionse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e2“there were competitive interactions between ions”
Claim · model-written summary
The intracellular Cd transport site decreased in affinity for ions in the order Ca > Cd > Mg >> K.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Outcome
- affinity of the intracellular Cd transport sitee3
- Direction
- decreasede3
- Qualifier
- in the order Ca > Cd > Mg ≫ Ke3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e3“The affinity of the intracellular Cd transport site for these ions decreased in the order Ca > Cd > Mg ≫ K”
Claim · model-written summary
Calcium was a competitive inhibitor of intracellular Cd uptake in moss.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Compound
- Calciume4
- Outcome
- intracellular Cd uptakee4
- Qualifier
- competitivee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e4“Calcium was shown to be competitive and Mg a non‐competitive inhibitor of intracellular Cd uptake”
Claim · model-written summary
Magnesium was a non-competitive inhibitor of intracellular Cd uptake in moss.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Compound
- Mge4
- Outcome
- intracellular Cd uptakee4
- Qualifier
- inhibitore4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e4“Calcium was shown to be competitive and Mg a non‐competitive inhibitor of intracellular Cd uptake”
Claim · model-written summary
Intracellular Cd uptake was optimal at about pH 5.6.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Outcome
- Intracellular Cd uptakee6
- Direction
- optimale6
- Value
- pH 5.6e6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e6“Intracellular Cd uptake, optimal at about pH 5.6”
Claim · model-written summary
pH highly sensitive for intracellular Cd uptake, primarily affecting Vmax.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Treatment
- pHe7
- Outcome
- V maxe7
- Direction
- primarily affectede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e7“was highly sensitive to pH, which primarily affected the V max”
Claim · model-written summary
Potassium supplied below 1 mM had no significant effect on Cd uptake.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Treatment
- Potassium, supplied at less than 1 mMe2
- Outcome
- Cd uptakee2
- Direction
- no significant effecte2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e2“Potassium, supplied at less than 1 mM, had no significant effect on Cd uptake”
Claim · model-written summary
KNO 3 above 1 mM stimulated transport site activity for Cd uptake.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Treatment
- at concentrations greater than 1 mM, KNO 3e2
- Outcome
- transport site activitye2
- Direction
- stimulatione2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e2“at concentrations greater than 1 mM, KNO 3 caused both a stimulation in transport site activity and reduced affinity for Cd”
Claim · model-written summary
KNO 3 above 1 mM reduced the affinity of moss for Cd.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Treatment
- at concentrations greater than 1 mM, KNO 3e2
- Outcome
- affinity for Cde2
- Direction
- reducede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e2“at concentrations greater than 1 mM, KNO 3 caused both a stimulation in transport site activity and reduced affinity for Cd”
Claim · model-written summary
KNO 3 pretreatment removed potentially competing ions from the cell wall.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Treatment
- Pretreatment with KNO 3e2
- Outcome
- potentially competing ions from the cell walle2
- Direction
- removede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e2“Pretreatment with KNO 3 removed potentially competing ions from the cell wall”
Claim · model-written summary
KNO 3 pretreatment increased the affinity of transport sites and extracellular exchange sites for Cd, Ca and Mg.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Treatment
- KNO 3 pretreatmente2
- Outcome
- affinity of both transport sites and extracellular exchange sitese2
- Direction
- highere2
- Qualifier
- for Cd, Ca and Mge2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e2“Reduced competition from ions removed by KNO 3 pretreatment resulted in a higher affinity of both transport sites and extracellular exchange sites for Cd, Ca and Mg”
Claim · model-written summary
Extracellular ionic environment provided by the cell wall regulates intracellular metal uptake.
- Taxon
- Rhytidiadelphus squarrosusRhytidiadelphus squarrosust0
- Outcome
- intracellular metal uptakee2
- Qualifier
- extracellular ionic environment provided by the cell walle2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Ionic control of intracellular and extracellular Cd uptake by the moss Rhytidiadelphus squarrosus”
e2“The results demonstrate quantitatively the regulatory effects on intracellular metal uptake of the extracellular ionic environment provided by the cell wall”