Ammonia Assimilation and Excretion in an Asymbiotic Strain of Anabaena azollae from Azolla filiculoides Lam.

William J. Zimmerman, Sammy Boussiba

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6 Scopus citations

Abstract

One independent, asymbiotic strain of Anabaena azollae isolated irom Azolla filiculoides Lam. was examined with respect to ammonia «uptake», assimilation, and excretion. Extracellular release of ammonia was initiated by adding L-methionine-D,L-sulfoximine (MSX). NH3-grown cells removed newly added ammonium from the medium faster (25.2 to 19.7nmol min−1 mg−1 protein), liberated ammonia more slowly (0.33 to 0.63 μmol h−1 mg−1 protein), and possessed lower glutamine synthetase (GS) transferase activity (55%) than the N2-grown cells. GS was always still partially active (20–40 % of uninhibited control) in A. azollae when excretion commenced. Uninhibited GS activity was lower than that of Anabaena sp. 7120. No optimum was observed between pH 5 and 9 for ammonia movement into or out of cells of A. azollae.

Original languageEnglish
Pages (from-to)443-450
Number of pages8
JournalJournal of Plant Physiology
Volume127
Issue number5
DOIs
StatePublished - 1 Jan 1987

Keywords

  • Anabaena azollae
  • GOGAT
  • GS
  • Glutamine synthetase
  • L-methionine-D,L-sulfoximine
  • MSX
  • ammonia excretion
  • ammonia uptake
  • cyanobacteria
  • glutamate synthase
  • glutamine synthetase
  • symbiosis

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