Abstract
Two cDNAs encoding functional carbonic anhydrase (CA) enzymes were recently isolated from a non-photosynthetic, cotyledon library of cotton (Gossypium hirsutum) seedlings with putative plastid-targeting sequences (GenBank accession nos. AF132854 and AF132855). Relative CA transcript abundance and enzyme activity increased 9 and 15 times, respectively, in cotton embryos during the maximum period of reserve oil accumulation. Specific sulfonamide inhibitors of CA activity significantly reduced the rate of [(14)C]acetate incorporation into total lipids in cotton embryos in vivo, and in embryo plastids in vitro, suggesting a role for CA in plastid lipid biosynthesis. CA inhibitors did not affect acetyl-coenzyme A carboxylase activity or total storage protein synthesis. Similar results were obtained for two other plant systems: cell suspensions (and isolated plastids therefrom) of tobacco (Nicotiana tabacum), and chloroplasts isolated from leaves of transgenic CA antisense-suppressed tobacco plants (5% of wild-type CA activity). In addition, tobacco cell suspensions treated with the CA inhibitor ethoxyzolamide showed a substantial loss of CO(2) compared with controls. The rate of [(14)C]acetate incorporation into lipid in cell suspensions was reduced by limiting external [CO(2)] (scrubbed air), and this rate was further reduced in the presence of ethoxyzolamide. Together, these results indicate that a reduction of CA activity (biochemical or molecular inhibition) impacts the rate of plant lipid biosynthesis from acetate, perhaps by impairing the ability of CA to efficiently "trap" inorganic carbon inside plastids for utilization by acetyl-coenzyme A carboxylase and the fatty acid synthesis machinery.
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Claims 11
Claim · model-written summary
Carbonic anhydrase transcript abundance increased ninefold in cotton embryos during peak reserve oil accumulation.
- Taxon
- cotton
Gossypium hirsutume0 - Organ / stage
- embryose0
- Gene
- CAe0
- Outcome
- Relative CA transcript abundancee0
- Direction
- increasede0
- Value
- 9e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Relative CA transcript abundance and enzyme activity increased 9 and 15 times, respectively, in cotton embryos during the maximum period of reserve oil accumulation”
Claim · model-written summary
Carbonic anhydrase enzyme activity increased fifteenfold in cotton embryos during peak reserve oil accumulation.
- Taxon
- cottonGossypium hirsutume0
- Organ / stage
- embryose0
- Gene
- CAe0
- Outcome
- enzyme activitye0
- Direction
- increasede0
- Value
- 15 timese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Relative CA transcript abundance and enzyme activity increased 9 and 15 times, respectively, in cotton embryos during the maximum period of reserve oil accumulation”
Claim · model-written summary
Carbonic anhydrase inhibitors significantly reduced acetate incorporation into total lipids in cotton embryos and embryo plastids.
- Taxon
- cottonGossypium hirsutume0
- Organ / stage
- embryose0
- Treatment
- Specific sulfonamide inhibitors of CA activitye0
- Outcome
- rate of [(14)C]acetate incorporation into total lipidse0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Specific sulfonamide inhibitors of CA activity significantly reduced the rate of [(14)C]acetate incorporation into total lipids in cotton embryos in vivo, and in embryo plastids in vitro”
Claim · model-written summary
Carbonic anhydrase inhibitors did not affect acetyl-coenzyme A carboxylase activity.
- Taxon
- CottonGossypium hirsutumt0
- Treatment
- CA inhibitorse0
- Outcome
- acetyl-coenzyme A carboxylase activitye0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CA inhibitors did not affect acetyl-coenzyme A carboxylase activity or total storage protein synthesis”
t0“Cotton Embryos”
Claim · model-written summary
Carbonic anhydrase inhibitors did not affect total storage protein synthesis.
- Taxon
- CottonGossypium hirsutumt0
- Treatment
- CA inhibitorse0
- Outcome
- total storage protein synthesise0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CA inhibitors did not affect acetyl-coenzyme A carboxylase activity or total storage protein synthesis”
t0“Cotton Embryos”
Claim · model-written summary
Similar lipid incorporation inhibition occurred in tobacco cell suspensions and their plastids.
- Taxon
- tobacco
Nicotiana tabacume0 - Organ / stage
- cell suspensionse0
- Outcome
- Similar resultse0
Not reportedTreatmentComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Similar results were obtained for two other plant systems: cell suspensions (and isolated plastids therefrom) of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Antisense suppressed tobacco leaf chloroplasts showed similar results with 5% of wild type carbonic anhydrase activity.
- Taxon
- tobaccoNicotiana tabacume0
- Organ / stage
- leavese0
- Treatment
- transgenic CA antisense-suppressede0
- Outcome
- CA activitye0
- Value
- 5%e0
- Comparator
- wild-typee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“chloroplasts isolated from leaves of transgenic CA antisense-suppressed tobacco plants (5% of wild-type CA activity)”
Claim · model-written summary
Ethoxyzolamide treated tobacco cell suspensions lost substantial CO2 relative to controls.
- Taxon
- tobaccoNicotiana tabacume0
- Organ / stage
- cell suspensionse0
- Treatment
- ethoxyzolamidee0
- Outcome
- CO(2)e0
- Direction
- losse0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tobacco cell suspensions treated with the CA inhibitor ethoxyzolamide showed a substantial loss of CO(2) compared with controls”
Claim · model-written summary
Limiting external CO2 reduced acetate incorporation into lipids in tobacco cell suspensions.
- Taxon
- TobaccoNicotiana tabacumt0
- Organ / stage
- cell suspensionse0
- Treatment
- limiting external [CO(2)] (scrubbed air)e0
- Outcome
- rate of [(14)C]acetate incorporation into lipide0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of [(14)C]acetate incorporation into lipid in cell suspensions was reduced by limiting external [CO(2)] (scrubbed air)”
t0“Tobacco Cell Suspensions”
Claim · model-written summary
Ethoxyzolamide further reduced acetate incorporation into lipids under limited external CO2 in tobacco cell suspensions.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- ethoxyzolamidee0
- Outcome
- this ratee0
- Direction
- further reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this rate was further reduced in the presence of ethoxyzolamide”
t0“Tobacco Cell Suspensions”
Claim · model-written summary
Authors suggest carbonic anhydrase inhibition may impair inorganic carbon trapping in plastids for lipid synthesis.
- Taxon
- CottonGossypium hirsutumt0
- Gene
- CAe0
- Outcome
- ability of CA to efficiently "trap" inorganic carbon inside plastidse0
- Qualifier
- perhapse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perhaps by impairing the ability of CA to efficiently "trap" inorganic carbon inside plastids for utilization by acetyl-coenzyme A carboxylase and the fatty acid synthesis machinery”
t0“Cotton Embryos”
The same questions in other papers
co2 · molecular: metabolites · Nicotiana tabacum (tobacco)Results differ
5 papers in the same direction as this paper · 4 in the opposite direction
- positive
- positive
- positive
6 papers more in this group
See all 10 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.