Azolla-Anabaena Relationship 1: XIII. Fixation of [13N]N2
AUTOR(ES)
Meeks, John C.
RESUMO
The major radioactive products of the fixation of [13N]N2 by Azolla caroliniana Willd.-Anabaena azollae Stras. were ammonium, glutamine, and glutamate, plus a small amount of alanine. Ammonium accounted for 70 and 32% of the total radioactivity recovered after fixation for 1 and 10 minutes, respectively. The presence of a substantial pool of [13N]N2-derived 13NH4+ after longer incubation periods was attributed to the spatial separation between the site of N2-fixation (Anabaena) and a second, major site of assimilation (Azolla). Initially, glutamine was the most highly radioactive organic product formed from [13N]N2, but after 10 minutes of fixation glutamate had 1.5 times more radiolabel than glutamine. These kinetics of radiolabeling, along with the effects of inhibitors of glutamine synthetase and glutamate synthase on assimilation of exogenous and [13N]N2-derived 13NH4+, indicate that ammonium assimilation occurred by the glutamate synthase cycle and that glutamate dehydrogenase played little or no role in the synthesis of glutamate by Azolla-Anabaena.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1056688Documentos Relacionados
- Azolla-Anabaena azollae Relationship: V. 15N2 Fixation, Acetylene Reduction, and H2 Production 12
- The Azolla-Anabaena azollae Relationship 1: XI. PHYCOBILIPROTEINS IN THE ACTION SPECTRUM FOR NITROGENASE-CATALYZED ACETYLENE REDUCTION
- Azolla-Anabaena azollae Relationship: IV. Photosynthetically Driven, Nitrogenase-catalyzed H2 Production 12
- Altered Nitrogenous Pools Induced by the Azolla-Anabaena Azolla Symbiosis
- Azolla-Anabaena Relationship: VIII. Photosynthetic Characterization of the Association and Individual Partners 12