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Reactions of Pseudomonas aeruginosa pyocyanin with reduced glutathione

100%

Cheluvappa R., Shimmon R., Dawson M., Hilmer S. N., Le Couteur D. G.

Acta Biochimica Polonica

2008

tom 55

nr 3

571-580

Pseudomonas aeruginosa is the most common cause of chronic and recurrent lung infections in patients with cystic fibrosis (CF) whose sputa contain copious quantities of P. aeruginosatoxin, pyocyanin. Pyocyanin triggers tissue damage mainly by its redox cycling and induction of reactive oxygen species (ROS). The reactions between reduced glutathione (GSH) and pyocyanin were observed using absorption spectra from spectrophotometry and the reaction products analysed by nuclear magnetic resonance imaging. Pyocyanin reacted with GSH non-enzymatically at 37°C resulting in the production of red-brown products, spectophotometrically visible as a 480 nm maximum absorption peak after 24 h of incubation. The reaction was concentration-dependent on reduced glutathione but not on pyocyanin. Minimizing the accessibility of oxygen to the reaction decreased its rate. The anti-oxidant enzyme catalase circumvented the reaction. Proton-NMR analysis demonstrated the persistence of the original aromatic ring and the methyl-group of pyocyanin in the red-brown products. Anti-oxidant agents having thiol groups produced similar spectophotometrically visible peaks. The presence of a previously unidentified non-enzymatic GSH-dependent metabolic pathway for pyocyanin has thus been identified. The reaction betweenpyocyanin and GSH is concentration-, time-, and O2-dependent. The formation of H2O2 as an intermediate and the thiol group in GSH seem to be important in this reaction.

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3D-analysis of plant microstructures: advantages and limitations of synchrotron X-ray microtomography

72%

Matsushima U., Graf W., Zabler S., Manke I., Dawson M., Choinka G., Hilger A., Herppich W. B.

International Agrophysics

2013

tom 27

nr 1

Synchrotron X-ray computer microtomography was used to analyze the microstructure of rose peduncles. Samples from three rose cultivars, differing in anatomy, were scanned to study the relation between tissue structure and peduncles mechanical strength. Additionally, chlorophyll fluorescence imaging and conventional light microscopy was applied to quantify possible irradiation-induced damage to plant physiology and tissue structure. The spatial resolution of synchrotron X-ray computer microtomography was sufficiently high to investigate the complex tissues of intact rose peduncles without the necessity of any preparation. However, synchrotron X-radiation induces two different types of damage on irradiated tissues. First, within a few hours after first X-ray exposure, there is a direct physical destruction of cell walls. In addition, a slow and delayed destruction of chlorophyll and, consequently, of photosynthetic activity occurred within hours/ days after the exposure. The results indicate that synchrotron X-ray computer microtomography is well suited for three-dimensional visualization of the microstructure of rose peduncles. However, in its current technique, synchrotron X-ray computer microtomography is not really non-destructive but induce tissue damage. Hence, this technique needs further optimization before it can be applied for time-series investigations of living plant materials.

Ograniczanie wyników

1 Acta Biochimica Polonica

1 International Agrophysics

2 Dawson M.

1 Cheluvappa R.

1 Choinka G.

1 Graf W.

1 Herppich W. B.

1 Hilger A.

1 Hilmer S. N.

1 Le Couteur D. G.

1 Manke I.

1 Matsushima U.

1 Shimmon R.

1 Zabler S.

1 2013

1 2008

Wyniki wyszukiwania

Reactions of Pseudomonas aeruginosa pyocyanin with reduced glutathione

3D-analysis of plant microstructures: advantages and limitations of synchrotron X-ray microtomography