Abstract
The symptoms of injury in microsomal membranes isolated from crowns of seedlings of Triticum aestivum , L. cultivar Fredrick after a lethal freeze‐thaw stress included an increased lipid phase transition temperature, loss of lipid phosphate (lipid‐P), and increased free fatty acid levels. However, minimal changes in fatty acid saturation were observed, suggesting minimal amounts of lipid peroxidation. All of these injury symptoms, including the lack of lipid peroxidation, were simulated in vitro by treatment of isolated membranes with oxygen free radicals, generated from either xanthine oxidase (EC 1.1.3.22) or paraquat (l,r‐dimethyl‐4,4′‐bipyridinium dichloride). Further evidence indicating a relationship between free radicals and freezing injury comes from the observation that both protoplasts and microsomal membranes isolated from wheat seedlings, that had been acclimated to induce freezing tolerance, also had increased tolerance of oxygen free radicals, and contained higher lipid‐soluble antioxidant levels, than those from non‐acclimated seedlings. Lipid‐soluble antioxidants accumulated in the crown tissue of the wheat seedling during the acclimation period. Freezing stress accelerated the formation of oxygen free radicals. Membranes isolated from crowns after a freeze–thaw stress tended to produce higher levels of superoxide as shown by the reduction of Tiron (1,2‐dihydroxy‐l,3‐benzenedisulfonic acid). In protoplasts, increased superoxide production coincided with lethal freezing injury. These results are discussed in terms of the possible involvement of oxygen free radicals in mediating aspects of freezing injury to cell membranes.
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Claims 12
Claim · model-written summary
Lethal freezing raised microsomal membrane lipid phase transition temperature.
- Taxon
- Triticum aestivum
Triticum aestivume0 - Material
- Fredricke0
- Organ / stage
- crownse0
- Treatment
- lethal freeze‐thaw stresse0
- Outcome
- lipid phase transition temperaturee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microsomal membranes isolated from crowns of seedlings of Triticum aestivum , L. cultivar Fredrick after a lethal freeze‐thaw stress included an increased lipid phase transition temperature”
Claim · model-written summary
Lethal freezing caused loss of membrane lipid phosphate.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- lethal freeze‐thaw stresse0
- Outcome
- lipid phosphate (lipid‐P)e0
- Direction
- losse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after a lethal freeze‐thaw stress included an increased lipid phase transition temperature, loss of lipid phosphate (lipid‐P), and increased free fatty acid levels.”
t0“winter wheat”
Claim · model-written summary
Lethal freezing increased free fatty acid levels.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- lethal freeze‐thaw stresse0
- Outcome
- free fatty acid levelse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after a lethal freeze‐thaw stress included an increased lipid phase transition temperature, loss of lipid phosphate (lipid‐P), and increased free fatty acid levels.”
t0“winter wheat”
Claim · model-written summary
Fatty acid saturation changed minimally after freezing.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- fatty acid saturatione0
- Direction
- minimal changese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“minimal changes in fatty acid saturation were observed”
Claim · model-written summary
Oxygen free radical treatment reproduced freezing injury symptoms in isolated wheat membranes.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- oxygen free radicalse0
- Outcome
- injury symptomse0
- Qualifier
- in vitroe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“All of these injury symptoms, including the lack of lipid peroxidation, were simulated in vitro by treatment of isolated membranes with oxygen free radicals, generated from either xanthine oxidase (EC 1.1.3.22) or paraquat (l,r‐dimethyl‐4,4′‐bipyridinium dichloride).”
Claim · model-written summary
Acclimated wheat protoplasts tolerated oxygen free radicals better than non acclimated protoplasts.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- protoplastse0
- Treatment
- acclimatede0
- Outcome
- tolerance of oxygen free radicalse0
- Direction
- increasede0
- Comparator
- non‐acclimated seedlingse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both protoplasts and microsomal membranes isolated from wheat seedlings, that had been acclimated to induce freezing tolerance, also had increased tolerance of oxygen free radicals, and contained higher lipid‐soluble antioxidant levels, than those from non‐acclimated seedlings.”
Claim · model-written summary
Acclimated wheat membranes tolerated oxygen free radicals better than non acclimated membranes.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- microsomal membranese0
- Treatment
- acclimatede0
- Outcome
- tolerance of oxygen free radicalse0
- Direction
- increasede0
- Comparator
- non‐acclimated seedlingse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both protoplasts and microsomal membranes isolated from wheat seedlings, that had been acclimated to induce freezing tolerance, also had increased tolerance of oxygen free radicals, and contained higher lipid‐soluble antioxidant levels, than those from non‐acclimated seedlings.”
Claim · model-written summary
Acclimated wheat protoplasts and membranes had higher lipid soluble antioxidant levels.
- Taxon
- wheatTriticum aestivume0
- Treatment
- acclimatede0
- Outcome
- lipid‐soluble antioxidant levelse0
- Direction
- highere0
- Comparator
- non‐acclimated seedlingse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both protoplasts and microsomal membranes isolated from wheat seedlings, that had been acclimated to induce freezing tolerance, also had increased tolerance of oxygen free radicals, and contained higher lipid‐soluble antioxidant levels, than those from non‐acclimated seedlings.”
Claim · model-written summary
Lipid soluble antioxidants accumulated in wheat crown tissue during acclimation.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- crown tissuee0
- Outcome
- Lipid‐soluble antioxidantse0
- Direction
- accumulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lipid‐soluble antioxidants accumulated in the crown tissue of the wheat seedling during the acclimation period.”
Claim · model-written summary
Freezing stress accelerated oxygen free radical formation.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- Freezing stresse0
- Outcome
- formation of oxygen free radicalse0
- Direction
- acceleratede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Freezing stress accelerated the formation of oxygen free radicals.”
Claim · model-written summary
Wheat crown membranes after freeze thaw stress tended to produce more superoxide.
- Taxon
- winter wheatTriticum aestivumt0
- Organ / stage
- crownse0
- Treatment
- freeze–thaw stresse0
- Outcome
- levels of superoxidee0
- Direction
- highere0
- Qualifier
- tendede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Membranes isolated from crowns after a freeze–thaw stress tended to produce higher levels of superoxide”
Claim · model-written summary
Increased superoxide production coincided with lethal freezing injury in wheat protoplasts.
- Taxon
- winter wheatTriticum aestivumt0
- Organ / stage
- protoplastse0
- Treatment
- lethal freezing injurye0
- Outcome
- superoxide productione0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“In protoplasts, increased superoxide production coincided with lethal freezing injury.”
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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.