Photosynthesis and nitrogenase activity in the blue-green alga Gloeocapsa

1974 ◽  
Vol 20 (12) ◽  
pp. 1633-1637 ◽  
Author(s):  
J. R. Gallon ◽  
T. A. LaRue ◽  
W. G. W. Kurz
Keyword(s):  
Nitrogen Fixation ◽  
Oxygen Evolution ◽  
Green Alga ◽  
Photosynthetic Pigments ◽  
Nitrogenase Activity ◽  
Photosynthetic Oxygen Evolution ◽  
Blue Green Alga ◽  
Temporal Separation ◽  
Young Culture ◽  
Photosynthetic Oxygen

In a young culture, photosynthetic-oxygen evolution by Gloeocapsa is at a low level while nitrogenase activity is at its greatest. When the culture ages, there is a rapid increase in photosynthetic pigments and oxygen evolution, and nitrogenase activity decreases. The temporal separation of nitrogen fixation and photosynthesis may serve to protect nitrogenase from oxygen denaturation.

Photorespiration and nitrogenase activity in the blue-green alga, Anabaena cylindrica

1972 ◽  
Vol 180 (1058) ◽  
pp. 87-102 ◽  
Keyword(s):  
Green Alga ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Dark Respiration ◽  
Reducing Power ◽  
Blue Green Alga ◽  
Anabaena Cylindrica ◽  
Oxygen Inhibition ◽  
Highly Sensitive ◽  
Photosynthetic Oxygen

Oxygen uptake in the light (photorespiration) by the nitrogen-fixing blue-green alga Anabaena cylindrica may be up to twenty times the dark respiration rate. The rate of uptake in the light increases linearly with increasing p O 2 while dark respiration is saturated at a p O 2 near 0.05 atm. Photorespiration is inhibited rapidly and completely by DCMU (3 x 10 -5 m) but KCN (10 -4 m) has little effect. Exogenously supplied hydroxyethane sulphonate (10 -5 m), an inhibitor of glycollate oxidase activity, and glycollate do not affect respiration, although 14 C-labelled glycollate is assimilated in the light and in the dark. Photorespiration is highly sensitive to p CO 2 and to NaHCO 3 concentration and approaches true photosynthetic oxygen production at the CO 2 compensation point of 10 parts/10 6 . A CO 2 concentration of 0.02 atm completely inhibits photorespiration whereas true photosynthesis is scarcely affected. Conditions which stimulate photorespiration (low p CO 2 and high p O 2 ) progressively inhibit acetylene reduction. In short-term studies DCMU inhibits acetylene reduction under condi­tions which stimulate photorespiration but has little effect under conditions which inhibit photorespiration. The results suggest that photorespiration and nitrogenase activity com­pete indirectly for reducing power and that at least one mechanism of oxygen inhibition of nitrogenase activity is via a stimulation of photorespiration.

Influence of Bleaching Herbicides on Chlorophyll and Carotenoids

1979 ◽  
Vol 34 (11) ◽  
pp. 1047-1051 ◽  
Author(s):  
Karl-Josef Kunert ◽  
Peter Böger
Keyword(s):  
Electron Transport ◽  
Oxygen Evolution ◽  
Green Alga ◽  
Photosynthetic Electron Transport ◽  
Pigment Content ◽  
Photosynthetic Oxygen Evolution ◽  
Direct Inhibition ◽  
Scenedesmus Acutus ◽  
Photosynthetic Oxygen ◽  
Chlorophyll Formation

Abstract Over 24 and 48 hour cultivation periods the influence of SAN 9789 (norflurazon), EMD-IT 5914 (difunon) and fluridone on growth, photosynthetic oxygen evolution and pigment content of the green alga Scenedesmus acutus was determined. Four effects were observed: a) Both carotenoid and chlorophyll formation were inhibited. b) Carotenoids were destroyed in the presence of air, but not nitrogen. The level of chlorophyll, however, did not change. c) β- (and α-) carotene was markedly decreased in the presence of oxygen. d) Photosynthetic oxygen evolution was decreased with the disappearance of carotenoids. These effects, which are accompanied by reduced growth, are believed to represent primary herbicidal modes of action. The decrease of oxygen evolution is not due to a direct inhibition of photosynthetic electron transport by the herbicides applied.

Nitrogen fixation and photosynthetic oxygen evolution in cyanobacteria

2003 ◽  
Vol 154 (3) ◽  
pp. 157-164 ◽  
Author(s):  
Ilana Berman-Frank ◽  
Pernilla Lundgren ◽  
Paul Falkowski
Keyword(s):  
Nitrogen Fixation ◽  
Oxygen Evolution ◽  
Photosynthetic Oxygen Evolution ◽  
Photosynthetic Oxygen
Sign in / Sign up

Export Citation Format

Share Document