Abstract
The effects of heat shock and heat adaptation on amino acid metabolism in cowpea suspension cultures were studied. Heat shock (from 26 to 42$\sp\circ$C) resulted in a several-fold increase in the accumulation of gamma-aminobutyric acid (GABA) within 4 hours. Experiments with gabaculine, a potent inhibitor of GABA aminotransferases (GABA AT), confirmed that this increase is due to an increase in GABA biosynthesis, and indicated that GABA utilization also increases. However, heat shock did not result in increased levels of GABA:pyruvate AT, GABA:2-oxoglutarate AT, or glutamate decarboxylase (GAD), the major enzyme of GABA biosynthesis. Measurements of GABA biosynthesis and utilization in the presence and absence of cycloheximide suggested that protein synthesis is not required for the maintenance of levels of these enzymes during heat shock. In 38$\sp\circ$C-adapted cells, GAD level was decreased, even though GABA was somewhat increased. When ($\sp{15}$N) -GABA was fed to cells incubated at 26 or 42$\sp\circ$C, alanine, glutamate and aspartate were the most heavily labeled amino acids. No amino acids other than GABA were labeled in the presence of gabaculine. GAD from heat-shocked cells had a K$\sb{\rm m}$ for glutamate ($\sim$3.5 mM), activity versus pH curve (pH optimum $\sim$5.1), and activity versus temperature curve (Q$\sb{10}\ \sim2$) identical to enzyme from control cells. Comparison of GAD activity in extracts before and after removal of small solutes revealed no evidence of enzyme activation or inhibition by low molecular weight effectors. Increased GABA biosynthesis during heat shock could possibly result from combined effects of cytoplasmic acidification, a 3-fold increase in reaction velocity due to the 16$\sp\circ$C increase in temperature, and altered compartmentation of glutamate.
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Claims 12
Claim · model-written summary
Heat shock increased GABA accumulation several-fold within four hours.
- Taxon
- cowpea
Vigna unguiculatat0 - Treatment
- Heat shock (from 26 to 42$\sp\circ$C)e0
- Outcome
- accumulation of gamma-aminobutyric acid (GABA)e0
- Direction
- increasee0
- Value
- several-folde0
- Qualifier
- within 4 hourse0
- Comparator
- 26e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heat shock (from 26 to 42$\sp\circ$C) resulted in a several-fold increase in the accumulation of gamma-aminobutyric acid (GABA) within 4 hours”
t0“cowpea”
Claim · model-written summary
The heat-induced GABA accumulation was attributed to increased biosynthesis.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- increase in GABA biosynthesise0
- Qualifier
- due to an increase in GABA biosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“confirmed that this increase is due to an increase in GABA biosynthesis”
t0“cowpea”
Claim · model-written summary
GABA utilization also increased during heat shock.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- GABA utilizatione0
- Direction
- increasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GABA utilization also increases”
t0“cowpea”
Claim · model-written summary
Heat shock did not increase levels of the three specified GABA metabolic enzymes.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- heat shocke0
- Outcome
- levels of GABA:pyruvate AT, GABA:2-oxoglutarate AT, or glutamate decarboxylase (GAD)e0
- Direction
- did not result in increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“heat shock did not result in increased levels of GABA:pyruvate AT, GABA:2-oxoglutarate AT, or glutamate decarboxylase (GAD)”
t0“cowpea”
Claim · model-written summary
Protein synthesis was suggested to be unnecessary to maintain enzyme levels during heat shock.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- maintenance of levels of these enzymese0
- Qualifier
- protein synthesis is not requirede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“protein synthesis is not required for the maintenance of levels of these enzymes during heat shock”
t0“cowpea”
Claim · model-written summary
GAD level decreased in heat-adapted cells.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- 38$\sp\circ$C-adaptede0
- Outcome
- GAD levele0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In 38$\sp\circ$C-adapted cells, GAD level was decreased”
t0“cowpea”
Claim · model-written summary
GABA increased somewhat in heat-adapted cells.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- GABAe0
- Direction
- increasede0
- Qualifier
- somewhate0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“even though GABA was somewhat increased”
t0“cowpea”
Claim · model-written summary
Alanine, glutamate and aspartate were the most heavily labeled amino acids after labeled GABA feeding.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- ($\sp{15}$N) -GABAe0
- Outcome
- alanine, glutamate and aspartate were the most heavily labeled amino acidse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When ($\sp{15}$N) -GABA was fed to cells incubated at 26 or 42$\sp\circ$C, alanine, glutamate and aspartate were the most heavily labeled amino acids”
t0“cowpea”
Claim · model-written summary
With gabaculine, no amino acids other than GABA were labeled.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- gabaculinee0
- Outcome
- No amino acids other than GABA were labelede0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No amino acids other than GABA were labeled in the presence of gabaculine”
t0“cowpea”
Claim · model-written summary
GAD kinetic and response curves were identical between heat-shocked and control cells.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- heat-shocked cellse0
- Outcome
- K$\sb{\rm m}$ for glutamate ($\sim$3.5 mM), activity versus pH curve (pH optimum $\sim$5.1), and activity versus temperature curve (Q$\sb{10}\ \sim2$)e0
- Direction
- identicale0
- Comparator
- control cellse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GAD from heat-shocked cells had a K$\sb{\rm m}$ for glutamate ($\sim$3.5 mM), activity versus pH curve (pH optimum $\sim$5.1), and activity versus temperature curve (Q$\sb{10}\ \sim2$) identical to enzyme from control cells”
t0“cowpea”
Claim · model-written summary
Removing small solutes revealed no evidence of GAD activation or inhibition by low molecular weight effectors.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- no evidence of enzyme activation or inhibition by low molecular weight effectorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no evidence of enzyme activation or inhibition by low molecular weight effectors”
t0“cowpea”
Claim · model-written summary
The authors proposed combined acidification, temperature and compartmentation effects for increased GABA biosynthesis.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- Increased GABA biosynthesise0
- Qualifier
- combined effects of cytoplasmic acidification, a 3-fold increase in reaction velocity due to the 16$\sp\circ$C increase in temperature, and altered compartmentation of glutamatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased GABA biosynthesis during heat shock could possibly result from combined effects of cytoplasmic acidification, a 3-fold increase in reaction velocity due to the 16$\sp\circ$C increase in temperature, and altered compartmentation of glutamate”
t0“cowpea”
The same questions in other papers
heat · molecular: metabolites · Vigna unguiculata (cowpea)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- negative
- positive
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.