Azolla-Anabaena relationship. XIII. Fixation of (/sup 13/N)N/sub 2/. [Azolla caroliniana; Anabaena azollae]

Journal Article · Wed Jul 01 00:00:00 EDT 1987 · Plant Physiol.; (United States)

OSTI ID:5905050

Meeks, J C; Steinberg, N A; Enderlin, C S; Joseph, C M; Peters, G A

The major radioactive products of the fixation of (/sup 13/N)N/sub 2/ 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 (/sup 13/N)N/sub 2/-derived /sup 13/NH/sub 4//sup +/ after long incubation periods was attributed to the spatial separation between the site of N/sub 2/-fixation (Anabaena) and a second, major site of assimilation (Azolla). Initially, glutamine was the most highly radioactive organic product formed from (/sup 13/N)N/sub 2/, 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 (/sup 13/N)N/sub 2/-derived /sup 13/NH/sub 4//sup +/, 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-Azabaena.

• Research Organization: Univ. of California, Davis
• OSTI ID: 5905050
• Journal Information: Plant Physiol.; (United States), Vol. 84:3
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GLUTAMIC ACID
BIOSYNTHESIS
LIGASES
ENZYME ACTIVITY
OXIDOREDUCTASES
PHOTOSYNTHETIC BACTERIA
NITROGEN FIXATION
ALANINES
AMMONIUM COMPOUNDS
AQUATIC ORGANISMS
BIOCHEMICAL REACTION KINETICS
ENZYME INHIBITORS
FERNS
GLUTAMINE
NITROGEN 13
SYMBIOSIS
TRACER TECHNIQUES
AMIDES
AMINO ACIDS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MINUTES LIVING RADIOISOTOPES
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PLANTS
RADIOISOTOPES
REACTION KINETICS
SYNTHESIS
550201* - Biochemistry- Tracer Techniques