Studies on nitric oxide (NO) formation by the green alga Scenedesmus obliquus and the diazotrophic cyanobacterium Anabaena doliolum.
This study provides preliminary evidence that NO production could be a general attribute of algae. Anabaena doliolum was found to be a better NO producer than Scenedesmus and Synechoccocus. Experiments conducted with inhibitors of photosynthesis (DCMU), ATP synthesis (DCCD), and the uncoupler (2,4-DNP) and its analog arsenate clearly revealed that inhibition of nitrite assimilation through the blockage of nitrite reductase (NiR) is primarily responsible for NO emission. A linear relationship between nitrite concentration in the culture medium and NO in the exhaust gas supports the view that accumulation of nitrite is responsible for NO formation. A failure of Scenedesmus, grown in the medium substituted with W for Mo, to produce either NO/NO-2 in light or a 'light-off' peak, and a resumption of these activities upon the addition of Mo proved beyond doubt that a functional nitrate reductase (NR) is necessary for the production of nitrite and NO by algae grown on nitrate as the nitrogen source. Moreover, the appearance of a NO peak immediately after nitrite supplementation under dark conditions in W-substituted cultures with or without glucose ruled out an enzymatic role of NR in NO emission.
Mallick
N
N
Forschungszentrum Juelich GmbH, Institut für Chemie und Dynamik der Geophäre-6, Germany.
Rai
L C
LC
Mohn
F H
FH
Soeder
C J
CJ
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D017033:Anabaena / Q000187:drug effects / Q000378:metabolism*; D001149:Arsenates / Q000494:pharmacology; D018533:Biomass; D000460:Chlorophyta / Q000187:drug effects / Q000378:metabolism*; D003470:Culture Media; D005947:Glucose / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D009573:Nitrites / Q000378:metabolism; D013045:Species Specificity; D014475:Uncoupling Agents / Q000494:pharmacology
D001149:Arsenates; D003470:Culture Media; D009573:Nitrites; D014475:Uncoupling Agents; D009569:Nitric Oxide; D005947:Glucose; C025657:arsenic acid; D019297:2,4-Dinitrophenol