Carotenoid Profiles in Pigment-Protein Complexes of Rhodospirillum rubrum

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Photoautotrophic cell suspension cultures of Chenopodium rubrum require high concentrations of nitrate and ammonium. During the growth phase total NH_4^+ and the greater portion of NO_3^- were consumed. During the stationary phase nitrate uptake continued but at a substantially smaller rate than during the growth phase. During growth the bulk of the absorbed N was incorporated into protein, the amount of which was then maintained constant until senescence. NO_3^- was accumulated upon transition between the growth and the stationary phase. NO_3^-, like the free amino acids, was deposited in the vacuole but, unlike these compounds, could not be remobilized upon transfer of the cells into N-free medium. Readdition of NH_4^+ to the medium, however, resulted in a mobilization of the vacuolar NO_3^--pool. Reutilization of both vacuolar N-storage pools must have been accomplished by recycling from the vacuole to the cyioplasm because N-metabolizing enzymes could not be detected in isolated vacuoles. Transfer of the cells of the stationary phase into medium containing NO_3^- and NH_4^+ resulted in an induction of nitrate uptake by the cells, but only after a lag phase of 4-5 days. It is conceivable that NH_4^+ induces NO_3^--translocating systems in the plasmalemma and in the tonoplast.
日本植物生理学会の論文