Abstract
In an endeavor to ascertain the effect of nitric oxide (NO) applied at ambient concentrations, which as formerly found are stress-inducing, experiments were carried out on stomatal guard cell chloroplasts of Pisum sativum (argentum mutant) epidermal leaf strips and also upon intact pea foliage. NO-related trials included a novel technique enabling chlorophyll fluorescence determination at subcellular sites, biophysical monitoring of surface tension of simulated chloroplast galactolipid monolayers - monogalactosyldiacylglycerol (MGDG), and comparison with palmitoyllinoleylphosphatidylcholine (PLPC), as well as lipoxygenase (LOX; EC 1.13.11.12) assay of foliage of intact plants treated with the NO-generating agent - S-nitroso-N-acetylpenicillamine (SNAP). It was found that at a very early stage, red chlorophyll fluorescence in the 690 nm region of guard cell chloroplasts manifested a highly statistically significant increase. This effect was accompanied by a marked increase of MGDG-monolayer surface tension and also by a SNAP concentration-dependent decrease of LOX activity. A further observation was that the superoxide free radical, like the NO free radical, also induced similar microviscosity changes of the MGDG chloroplast membrane galactolipid. However, the combination of the two radicals, to purportedly form the peroxynitrite (HOONO) adduct, was not additive. Results are discussed in light of a combined biophysical and biochemical effect on the π component of the C=C double bonds in chloroplast membrane galactolipids. Such bonding inter alia may lower efficiency of photosynthetic electron transport and so doing may be a contributing factor to the multifaceted endogenous stress or exogenous pollution syndrome.
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Claims 5
Claim · model-written summary
Nitric oxide at ambient concentrations significantly increased red chlorophyll fluorescence at 690 nm in guard cell chloroplasts.
- Taxon
- Pisum sativum
Lathyrus oleraceuse0 - Organ / stage
- guard cell chloroplastse2
- Treatment
- nitric oxide (NO) applied at ambient concentrationse1
- Outcome
- red chlorophyll fluorescence in the 690 nm regione2
- Direction
- increasee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal guard cell chloroplasts of Pisum sativum (argentum mutant)”
e1“effect of nitric oxide (NO) applied at ambient concentrations”
e2“red chlorophyll fluorescence in the 690 nm region of guard cell chloroplasts manifested a highly statistically significant increase”
Claim · model-written summary
A SNAP concentration-dependent decrease of LOX activity was observed in pea foliage.
- Taxon
- Pisum sativumLathyrus oleraceuse0
- Treatment
- SNAP concentratione3
- Outcome
- LOX activitye3
- Direction
- decreasee3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal guard cell chloroplasts of Pisum sativum (argentum mutant)”
e3“a SNAP concentration-dependent decrease of LOX activity”
Claim · model-written summary
Superoxide radical induced microviscosity changes of the MGDG chloroplast membrane galactolipid similar to NO.
- Taxon
- Pisum sativumLathyrus oleraceuse0
- Treatment
- superoxide free radicale4
- Outcome
- microviscosity changes of the MGDG chloroplast membrane galactolipide4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal guard cell chloroplasts of Pisum sativum (argentum mutant)”
e4“the superoxide free radical, like the NO free radical, also induced similar microviscosity changes of the MGDG chloroplast membrane galactolipid”
Claim · model-written summary
Combining superoxide and NO radicals was not additive in forming the peroxynitrite adduct effect.
- Taxon
- Pisum sativumLathyrus oleraceuse0
- Treatment
- combination of the two radicalse5
- Outcome
- peroxynitrite (HOONO) adducte5
- Direction
- not additivee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal guard cell chloroplasts of Pisum sativum (argentum mutant)”
e5“the combination of the two radicals, to purportedly form the peroxynitrite (HOONO) adduct, was not additive”
Claim · model-written summary
Oxidation of C=C bonds in chloroplast galactolipids may lower the efficiency of photosynthetic electron transport.
- Taxon
- Pisum sativumLathyrus oleraceuse0
- Outcome
- efficiency of photosynthetic electron transporte6
- Qualifier
- π component of the C=C double bonds in chloroplast membrane galactolipidse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal guard cell chloroplasts of Pisum sativum (argentum mutant)”
e6“Results are discussed in light of a combined biophysical and biochemical effect on the π component of the C=C double bonds in chloroplast membrane galactolipids. Such bonding inter alia may lower efficiency of photosynthetic electron transport”