Abstract
Iron uptake by excised rice roots can be described in kinetic terms of active absorption and the formation of ion-carrier complexes. Conventional interpretation indicates two carriers, one of which is responsible for iron absorption at low concentrations, with the second primarily functioning at high iron levels. The maximum absorption of both carriers vanes greatly between varieties, the variety Pebifun having much greater absorptive capacity than either Siam-29 or Paldal. Varietal differences in uptake capacity primarily depend on total carrier concentration, 0.93,0.40, and 0.31 μ moles per g roots of Pebifun, Siam-29, and Paldal respectively. Although the kinetic treatment suggests two carriers, the chromatographic evidence indicates the presence of the iron primarily in one major initial complex, with suggestions of accumulation rather than turnover. An alternative to the carrier hypothesis is therefore put forward which regards the accumulation of iron as binding initially on to one or several closely related substances, followed by incorporation into secondary products when a critical level of the initial product is exceeded. Manganese was found to competitively inhibit iron uptake by rice roots. Inhibition was more severe in Siam-29 than in Paldal and can be explained on the basis of carrier concentration and competition for the same carrier site. Copper was found not to be competitive for the iron absorption sites. The effect of copper was not significant with the low levels of iron but only with the 5 × 10−4 M Fe level. The effect varied between varieties, in Pebifun both 5 × 10−5 and 5 × 10−6 M Cu inhibited iron uptake compared with the control. In the case of Siam-29 both copper levels accelerated iron uptake, 5 × 10−5 M Cu giving the greatest uptake. With 5 × 10−5 M Cu Pebifun took up much less iron than Siam-29. The mecharosm of copper inhibition/stimulation is highly speculative.
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Claims 16
Claim · model-written summary
Rice root iron uptake was described by active absorption and ion-carrier complex formation.
- Taxon
- rice
Oryza sativae0 - Organ / stage
- excised rice rootse0
- Outcome
- Iron uptakee0
- Qualifier
- active absorption and the formation of ion-carrier complexese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Iron uptake by excised rice roots can be described in kinetic terms of active absorption and the formation of ion-carrier complexes”
Claim · model-written summary
Kinetic interpretation indicated one carrier for low iron concentrations and another mainly for high levels.
- Taxon
- RiceOryza sativat0
- Outcome
- iron absorptione0
- Qualifier
- two carrierse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Conventional interpretation indicates two carriers, one of which is responsible for iron absorption at low concentrations, with the second primarily functioning at high iron levels”
t0“Rice Roots”
Claim · model-written summary
Pebifun had greater maximum iron absorptive capacity than Siam-29 or Paldal.
- Taxon
- RiceOryza sativat0
- Material
- Pebifune0
- Outcome
- absorptive capacitye0
- Direction
- much greatere0
- Comparator
- Siam-29 or Paldale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the variety Pebifun having much greater absorptive capacity than either Siam-29 or Paldal”
t0“Rice Roots”
Claim · model-written summary
Pebifun total carrier concentration was 0.93 μ moles per g roots.
- Taxon
- RiceOryza sativat0
- Material
- Pebifune0
- Outcome
- total carrier concentratione0
- Value
- 0.93e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total carrier concentration, 0.93,0.40, and 0.31 μ moles per g roots of Pebifun, Siam-29, and Paldal respectively”
t0“Rice Roots”
Claim · model-written summary
Siam-29 total carrier concentration was 0.40 μ moles per g roots.
- Taxon
- RiceOryza sativat0
- Material
- Siam-29e0
- Outcome
- total carrier concentratione0
- Value
- 0.40e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total carrier concentration, 0.93,0.40, and 0.31 μ moles per g roots of Pebifun, Siam-29, and Paldal respectively”
t0“Rice Roots”
Claim · model-written summary
Paldal total carrier concentration was 0.31 μ moles per g roots.
- Taxon
- RiceOryza sativat0
- Material
- Paldale0
- Outcome
- total carrier concentratione0
- Value
- 0.31 μ moles per g rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total carrier concentration, 0.93,0.40, and 0.31 μ moles per g roots of Pebifun, Siam-29, and Paldal respectively”
t0“Rice Roots”
Claim · model-written summary
Chromatography indicated iron primarily in one major initial complex, suggesting accumulation rather than turnover.
- Taxon
- RiceOryza sativat0
- Outcome
- iron primarily in one major initial complexe0
- Qualifier
- suggestions of accumulation rather than turnovere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the chromatographic evidence indicates the presence of the iron primarily in one major initial complex, with suggestions of accumulation rather than turnover”
t0“Rice Roots”
Claim · model-written summary
The authors proposed initial iron binding followed by incorporation into secondary products above a critical level.
- Taxon
- RiceOryza sativat0
- Outcome
- incorporation into secondary productse0
- Qualifier
- binding initially on to one or several closely related substancese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“binding initially on to one or several closely related substances, followed by incorporation into secondary products when a critical level of the initial product is exceeded”
t0“Rice Roots”
Claim · model-written summary
Manganese competitively inhibited rice root iron uptake.
- Taxon
- riceOryza sativae0
- Treatment
- Manganesee0
- Outcome
- iron uptakee0
- Direction
- inhibite0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Manganese was found to competitively inhibit iron uptake by rice roots”
Claim · model-written summary
Manganese inhibition was more severe in Siam-29 than Paldal.
- Taxon
- riceOryza sativae1
- Material
- Siam-29e0
- Treatment
- Manganesee1
- Outcome
- Inhibitione0
- Direction
- more severee0
- Comparator
- Paldale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inhibition was more severe in Siam-29 than in Paldal”
e1“Manganese was found to competitively inhibit iron uptake by rice roots”
Claim · model-written summary
Copper was not competitive for iron absorption sites.
- Taxon
- RiceOryza sativat0
- Treatment
- Coppere0
- Outcome
- not to be competitive for the iron absorption sitese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Copper was found not to be competitive for the iron absorption sites”
t0“Rice Roots”
Claim · model-written summary
At low iron levels, the copper effect was not significant.
- Taxon
- RiceOryza sativat0
- Treatment
- coppere0
- Outcome
- effect of coppere0
- Qualifier
- low levels of irone0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect of copper was not significant with the low levels of iron”
t0“Rice Roots”
Claim · model-written summary
At 5 × 10−4 M Fe, copper had an effect.
- Taxon
- RiceOryza sativat0
- Treatment
- coppere1
- Outcome
- effect of coppere1
- Qualifier
- 5 × 10−4 M Fee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but only with the 5 × 10−4 M Fe level. The effect varied between varieties”
e1“The effect of copper was not significant with the low levels of iron but only with the 5 × 10−4 M Fe level”
t0“Rice Roots”
Claim · model-written summary
In Pebifun, both tested copper levels inhibited iron uptake versus control.
- Taxon
- RiceOryza sativat0
- Material
- Pebifune0
- Treatment
- 5 × 10−5 and 5 × 10−6 M Cue0
- Outcome
- iron uptakee0
- Direction
- inhibitede0
- Comparator
- the controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in Pebifun both 5 × 10−5 and 5 × 10−6 M Cu inhibited iron uptake compared with the control”
t0“Rice Roots”
Claim · model-written summary
In Siam-29, both tested copper levels accelerated iron uptake, with greatest uptake at 5 × 10−5 M Cu.
- Taxon
- RiceOryza sativat0
- Material
- Siam-29e0
- Treatment
- copper levelse0
- Outcome
- iron uptakee0
- Direction
- acceleratede0
- Qualifier
- 5 × 10−5 M Cu giving the greatest uptakee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the case of Siam-29 both copper levels accelerated iron uptake, 5 × 10−5 M Cu giving the greatest uptake”
t0“Rice Roots”
Claim · model-written summary
At 5 × 10−5 M Cu, Pebifun took up less iron than Siam-29.
- Taxon
- RiceOryza sativat0
- Material
- Pebifune0
- Treatment
- 5 × 10−5 M Cue0
- Outcome
- irone0
- Direction
- much lesse0
- Comparator
- Siam-29e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With 5 × 10−5 M Cu Pebifun took up much less iron than Siam-29”
t0“Rice Roots”
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