Pathway of ammonium assimilation in a marine diatom determined with the radiotracer sup 13 N. [Thalassiosira pseudonoana (Hustedt)]
- State Univ. of New York, Stony Brook (USA)
- Brookhaven National Laboratory, Upton, NY (USA)
In unicellular algae, ammonium can be assimilated into glutamate through the action of glutamate dehydrogenase (GDH) or into glutamine through the sequential activities of glutamine synthetase and glutamate 2-oxoglutarate amidotransferase (GS-GOGAT pathway). We have shown that the first radio-labeled product of assimilation of {sup 13}NH{sub 4}{sup +} (t{sub {1/2}} = 10 min) was glutamine in the marine diatom Thalassiosira pseudonana (Hustedt). When GS-GOGAT was inhibited with methionine sulfoximine, the incorporation of radioactivity into both glutamine and glutamate was blocked, implying that the radiolabeled glutamate is formed from glutamine. Glutamine was also the first labeled product when the intracellular concentration of ammonium was elevated by preincubation with unlabeled ammonium. The results indicate that the GS-GOGAT pathway is the primary pathway for the assimilation of nitrogen in T. pseudonana.
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 7266753
- Journal Information:
- Journal of Phycology; (USA), Journal Name: Journal of Phycology; (USA) Vol. 24:4; ISSN 0022-3646; ISSN JPYLA
- Country of Publication:
- United States
- Language:
- English
Similar Records
/sup 15/N-Ammonia assimilation, 2-oxoglutarate transport, and glutamate export in spinach chloroplasts in the presence of dicarboxylates in the light
sup 13 N isotope studies of glutamine assimilation pathways in Neurospora crassa
Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALGAE
AMIDES
AMINO ACIDS
AMMONIUM COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOLOGICAL PATHWAYS
CARBOXYLIC ACIDS
CHROMOPHYCOTA
DIATOMS
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENZYME ACTIVITY
ENZYMES
GLUTAMINE
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
METABOLISM
MINUTES LIVING RADIOISOTOPES
NITRO-GROUP DEHYDROGENASES
NITROGEN
NITROGEN 13
NITROGEN ISOTOPES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
PLANTS
RADIOISOTOPES
TRACER TECHNIQUES