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Oxidative stress and the antioxidant...

Cunningham, Kelly Ann.

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Oxidative stress and the antioxidant enzyme superoxide dismutase in nitrogen-fixing cyanobacteria.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Oxidative stress and the antioxidant enzyme superoxide dismutase in nitrogen-fixing cyanobacteria./
Author:	Cunningham, Kelly Ann.
Description:	168 p.
Notes:	Source: Dissertation Abstracts International, Volume: 58-06, Section: B, page: 2842.
Contained By:	Dissertation Abstracts International58-06B.
Subject:	Biology, Microbiology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9736544
ISBN:	0591465841

Oxidative stress and the antioxidant enzyme superoxide dismutase in nitrogen-fixing cyanobacteria.
Cunningham, Kelly Ann.

Oxidative stress and the antioxidant enzyme superoxide dismutase in nitrogen-fixing cyanobacteria. - 168 p.

Source: Dissertation Abstracts International, Volume: 58-06, Section: B, page: 2842.

Thesis (Ph.D.)--University of Maryland, College Park, 1997.

Although essential to all aerobic life, oxygen can be toxic via production of reactive oxygen derivatives. This study investigated the response to reactive oxygen in diazotrophic cyanobacteria, and the role of superoxide dismutase (SOD) as an antioxidant enzyme, particularly in relation to nitrogen-fixation. Marine (Trichodesmium) and terrestrial (Gloeothece) cyanobacterial isolates from high- and low-light environments respectively were studied. Both can fix nitrogen, an oxygen-sensitive process, under aerobic conditions while simultaneously producing photosynthetic oxygen. Nitrogen fixation (acetylene reduction) in Trichodesmium was more resistant than in Gloeothece to oxidative damage by additions of the oxidants

ISBN: 0591465841Subjects--Topical Terms:

1017734
Biology, Microbiology.

Oxidative stress and the antioxidant enzyme superoxide dismutase in nitrogen-fixing cyanobacteria.
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020 $a 0591465841
035 $a (UnM)AAI9736544
035 $a AAI9736544
040 $a UnM $c UnM
100 1 $a Cunningham, Kelly Ann. $3 1940047
245 1 0 $a Oxidative stress and the antioxidant enzyme superoxide dismutase in nitrogen-fixing cyanobacteria.
300 $a 168 p.
500 $a Source: Dissertation Abstracts International, Volume: 58-06, Section: B, page: 2842.
500 $a Chair: Douglas G. Capone.
502 $a Thesis (Ph.D.)--University of Maryland, College Park, 1997.
520 $a Although essential to all aerobic life, oxygen can be toxic via production of reactive oxygen derivatives. This study investigated the response to reactive oxygen in diazotrophic cyanobacteria, and the role of superoxide dismutase (SOD) as an antioxidant enzyme, particularly in relation to nitrogen-fixation. Marine (Trichodesmium) and terrestrial (Gloeothece) cyanobacterial isolates from high- and low-light environments respectively were studied. Both can fix nitrogen, an oxygen-sensitive process, under aerobic conditions while simultaneously producing photosynthetic oxygen. Nitrogen fixation (acetylene reduction) in Trichodesmium was more resistant than in Gloeothece to oxidative damage by additions of the oxidants $\ rm O\sb2\sp-{\cdot} $ and $\ rm H\sb2O\sb2, $ suggesting adaptation in Trichodesmium to the photooxidizing conditions it typically encounters. The deleterious effect of $\ rm O\sb2\sp-{\cdot} $ on Trichodesmium was countered by exogenous additions of the antioxidant enzymes SOD and catalase. Specific SOD activity (measured spectrophotometrically) in Trichodesmium did not respond to short-term (hours-long) changes in oxygen or light regime, whereas Gloeothece cultures acclimated to varying light regimes showed significantly increased specific SOD activity with increased light intensity and exposure. This implies that Trichodesmium SOD does not participate in a response to acute photooxidative stress, but that prolonged exposure to high light, such as during a sustained surface bloom, is likely needed to induce changes in SOD activity. Diel experiments in freshly-collected Trichodesmium revealed that specific SOD activity peaks during early morning, declines throughout the day and reaches a low at night. The diel pattern did not closely parallel that of nitrogen fixation. In Gloeothece cultures grown on a light/dark cycle, specific SOD activity did not show any diel variation, and was greater in NH $\ sb4\sp+ $- grown than in N $\ sb2 $- fixing cultures. These results indicate that nitrogenase function and diel activity in Trichodesmium and Gloeothece are not directly dependent on increased antioxidant protection from SOD. The SOD in Trichodesmium was found to be the iron-containing metallotype, as has been reported for other cyanobacteria.
590 $a School code: 0117.
650 4 $a Biology, Microbiology. $3 1017734
650 4 $a Chemistry, Biochemistry. $3 1017722
690 $a 0410
690 $a 0487
710 2 0 $a University of Maryland, College Park. $3 657686
773 0 $t Dissertation Abstracts International $g 58-06B.
790 1 0 $a Capone, Douglas G., $e advisor
790 $a 0117
791 $a Ph.D.
792 $a 1997
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9736544