Abstract
The effects of radiation‐mediated free radical production on polyamine metabolism were investigated in grape cells ( Vitis vinifera L. cv. Gamay) using a cell suspension culture. Putrescine (Put) synthesis was triggered in irradiated cells (0. 5 kGy) only when ammonium was present in the culture medium. Under these conditions. Put accumulated to a continuously high level. As also described for other kinds of stress, the level of spermidine was slightly enhanced and that of spermine unchanged. The role of ammonium was assessed by studying non‐irradiated cell cultures. In the presence of ammonium, a transient increase of both arginine decarboxylase (ADC) activity and of Put synthesis was observed during the lag phase of growth. This Put enhancement was inhibited by difluoromethyl arginine and not by difluoromethyl ornithine, showing that increased Put synthesis occurs via the ADC pathway. When ammonium was withheld from the culture medium. ADC activity was still triggered though transient Put accumulation was completely suppressed. These results emphasize the importance of ammonium availability in cultured cells as a limiting factor for Put production. Polyamine synthesis, therefore, cannot be stimulated by gamma irradiation in the absence of an ammonium supply. These results support the hypothesis that Put synthesis is a detoxification process of the ammonium produced as a result of nitrogen recycling within stressed plant cells.
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Claims 10
Claim · model-written summary
Irradiation triggered putrescine synthesis only with ammonium present.
Verbatim
e0“Putrescine (Put) synthesis was triggered in irradiated cells (0. 5 kGy) only when ammonium was present in the culture medium.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Putrescine accumulated continuously at a high level under irradiation with ammonium.
Verbatim
e0“Under these conditions. Put accumulated to a continuously high level.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Spermidine level was slightly enhanced.
Verbatim
e0“the level of spermidine was slightly enhanced and that of spermine unchanged.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Spermine level was unchanged.
Verbatim
e0“the level of spermidine was slightly enhanced and that of spermine unchanged.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Ammonium transiently raised ADC activity in nonirradiated grape cells.
- Taxon
- grapee1
- Treatment
- presence of ammoniume0
- Outcome
- arginine decarboxylase (ADC) activitye0
- Direction
- increasee0
Not reportedComparator
Verbatim
e0“In the presence of ammonium, a transient increase of both arginine decarboxylase (ADC) activity and of Put synthesis was observed during the lag phase of growth.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Ammonium transiently raised Put synthesis in nonirradiated grape cells.
Not reportedComparator
Verbatim
e0“In the presence of ammonium, a transient increase of both arginine decarboxylase (ADC) activity and of Put synthesis was observed during the lag phase of growth.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Difluoromethyl arginine inhibited Put enhancement.
Not reportedComparator
Verbatim
e0“This Put enhancement was inhibited by difluoromethyl arginine and not by difluoromethyl ornithine”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Difluoromethyl ornithine did not inhibit Put enhancement.
Not reportedComparator
Verbatim
e0“This Put enhancement was inhibited by difluoromethyl arginine and not by difluoromethyl ornithine”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Withholding ammonium still triggered ADC activity.
Not reportedComparator
Verbatim
e0“When ammonium was withheld from the culture medium. ADC activity was still triggered though transient Put accumulation was completely suppressed.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
Claim · model-written summary
Withholding ammonium completely suppressed transient Put accumulation.
- Taxon
- grapee1
- Treatment
- ammonium was withhelde0
- Outcome
- transient Put accumulatione0
- Direction
- suppressede0
Not reportedComparator
Verbatim
e0“When ammonium was withheld from the culture medium. ADC activity was still triggered though transient Put accumulation was completely suppressed.”
e1“grape cells ( Vitis vinifera L. cv. Gamay)”
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See all 20 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.