Abstract
Apprehension over the adequncy of current techniques stimulated a detailed study of the time factor in the arsenate inhibition of growth and respiration in excised stem and root sections of Pisum sativum. Growth inhibition by arsenate sets in very slowly, its rate of onset being related to the molar concentration (C) of arsenate ate by the relation where T50 is the time taken in hours to reduce the growth rate to 50 per cent of the control and K is a constant. An explanation of the physiological basis of this relationship is attempted. Estimates were made of the final steady growth rate (relative to control) in various arsenate concentrations. The inhibitions calculated from this rate are held to approximate to the true arsenate effect and are shown to be very different from those calculated from ‘total growth’ measures. Respiration of growing stem sections is not inhibited by the low arsenate concentrations that inhibit growth. Some inhibition is indicated at high concentrations (3 × 10−4M. and over) but only after 15-20 hours of exposure. Two per cent sucrose has no effect on the arsenate inhibiition of stem growth. Sucrose, however, markedly stimulates respiration in stem sections, but this stimulation is prevented by arsenate. The misinterpretations which may arise as a result of ignoring the time factor in inhibition studies in excised organ sections are discussed and the desirability of constructing complete growth curves in all such studies is stressed.
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Claims 8
Claim · model-written summary
Arsenate growth inhibition developed slowly, with onset related to concentration.
- Taxon
- Pisum sativum
Lathyrus oleraceuse1 - Treatment
- arsenatee0
- Outcome
- rate of onsete0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Growth inhibition by arsenate sets in very slowly, its rate of onset being related to the molar concentration (C) of arsenate”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
Claim · model-written summary
Steady growth rate estimates gave different arsenate inhibition estimates from total growth measures.
- Taxon
- Pisum sativumLathyrus oleraceuse1
- Outcome
- inhibitions calculated from this ratee0
- Comparator
- ‘total growth’ measurese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The inhibitions calculated from this rate are held to approximate to the true arsenate effect and are shown to be very different from those calculated from ‘total growth’ measures.”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
Claim · model-written summary
Low arsenate concentrations inhibited growth without inhibiting stem respiration.
- Taxon
- Pisum sativumLathyrus oleraceuse1
- Treatment
- low arsenate concentrationse0
- Outcome
- Respiration of growing stem sectionse0
- Direction
- not inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Respiration of growing stem sections is not inhibited by the low arsenate concentrations that inhibit growth.”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
Claim · model-written summary
High arsenate concentrations inhibited respiration only after prolonged exposure.
- Taxon
- Pisum sativumLathyrus oleraceuse1
- Treatment
- high concentrations (3 × 10−4M. and over)e0
- Outcome
- inhibitione0
- Direction
- inhibitione0
- Qualifier
- only after 15-20 hours of exposuree0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Some inhibition is indicated at high concentrations (3 × 10−4M. and over) but only after 15-20 hours of exposure.”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
Claim · model-written summary
Two per cent sucrose did not alter arsenate inhibition of stem growth.
- Taxon
- Pisum sativumLathyrus oleraceuse1
- Treatment
- Two per cent sucrosee0
- Outcome
- arsenate inhibiition of stem growthe0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Two per cent sucrose has no effect on the arsenate inhibiition of stem growth.”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
Claim · model-written summary
Sucrose stimulated respiration in stem sections.
- Taxon
- Pisum sativumLathyrus oleraceuse1
- Treatment
- Sucrosee0
- Outcome
- respiration in stem sectionse0
- Direction
- stimulatese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sucrose, however, markedly stimulates respiration in stem sections”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
Claim · model-written summary
Arsenate prevented sucrose stimulation of stem respiration.
- Taxon
- Pisum sativumLathyrus oleraceuse1
- Treatment
- arsenatee0
- Outcome
- stimulatione0
- Direction
- preventede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this stimulation is prevented by arsenate.”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
Claim · model-written summary
The authors recommend complete growth curves in inhibition studies.
- Taxon
- Pisum sativumLathyrus oleraceuse1
- Outcome
- constructing complete growth curvese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the desirability of constructing complete growth curves in all such studies is stressed.”
t0“The Time Factor in Studies of Growth Inhibition in Excised Organ Sections”
e1“excised stem and root sections of Pisum sativum.”
The same questions in other papers
sucrose · growth · Lathyrus oleraceus (pea)Positive and negative results
2 papers in the same direction as this paper · 8 in the opposite direction
- positive
- positive
- positive
7 papers more in this group
See all 11 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.