This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (18) Citing Articles via Google Scholar Google Scholar Articles by Campbell, W. H. Articles by Beck, E. Search for Related Content PubMed PubMed Citation Articles by Campbell, W. H. Articles by Beck, E. Agricola Articles by Campbell, W. H. Articles by Beck, E.

Articles

Development of Nitrogen Assimilation Enzymes during Photoautotrophic Growth of Chenopodium rubrum Suspension Cultures ¹

Botantisches Institut der Universität Bayreuth, Lehrstuhl für Pflanzenphysiologie, Universitätsstrasse 30, D-8580 Bayreuth, West Germany

Chenopodium rubrum cells were grown in suspension as a photoautotrophic culture with a 16 hour day. Cell growth had three phases: a 3-day lag, a 3-week logarithmic phase, and a 10-day stationary phase. Chlorophyll content increased steadily during log phase and reached a level of 0.5 to 0.6 mg Chl g^–1 fresh weight. Soluble protein of the cells increased more rapidly from day 4 to day 12 than during midlog phase. Initially, ammonium was taken up in preference to nitrate. However, during the second two weeks of growth, ammonium and nitrate were taken up simultaneously; this period of growth was the time of highest rates of N uptake by the cultured cells. Glutamine synthetase had a high specific activity (17 µmol·hour^–1 mg^–1 protein) in day 1 cells, and this level was sustained until midlog phase when it increased by 20%. Methyl viologen-dependent glutamate synthase specific activity increased rapidly in lag phase cells (day 4 = 10 µmol·hour^–1 mg^–1 protein), but decreased by day 9 to about 50% of the peak and remained constant. NADH:nitrate reductase specific activity increased rapidly in lag phase cells and reached a plateau that lasted from day 4 to 14 (1 µmol·hour^–1 mg^–1 protein). Methyl viologen-dependent nitrite reductase specific activity was high when assayed on day 5 and increased to a maximum on day 15 to 16 (12 µmol·hour^–1 mg^–1 protein). NADPH- and NADH-dependent glutamate dehydrogenase specific activities remained rather constant throughout the growth cycle. The cells appeared to have developed photosynthetic competence and to have leaf-like activities of nitrogen assimilation enzymes.

¹ This research was supported by Deutsche Forschungsgemeinschaft Grant SFB No. 137.