FLUCTUATIONS IN FREE AMINO ACID POOLS OF GYMNODINIUM SIMPLEX (DINOPHYCEAE) IN RESPONSE TO AMMONIA PERTURBATION: EVIDENCE FOR GLUTAMINE SYNTHETASE PATHWAY1,2 |
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Authors: | David H. Turpin Paul J. Harrison |
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Abstract: | An ammonia limited chemostat culture of Gymnodinium simplex (Lohm.) Kofoid & Swezy was perturbed with ammonia and fluctuations in the free intracellular amino acid pools were followed 80 min. The steady-state value of glutamate was 2.07 ± 10-15 mol cell-1 and of glutamine was 0.31 ± 10-15 mol cell-1. Five minutes after the perturbation, a substantial rise in glutamine was observed with a corresponding decrease in glutamate. This is considered a result of glutamine synthetase acting as the primary ammonia assimilating enzyme. The level of ammonia and the major free amino acids reached a maximum 10 min after the perturbation and then slowly decreased. |
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Keywords: | ammonia limitation ammonia assimilation free amino acids dinoflagellate glutamate glutamate dehydrogenase glutamine glutamine synthetase Gymnodinium |
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