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NUTRITIONAL STUDIES OF TWO RED ALGAE. II. KINETICS OF AMMONIUM AND NITRATE UPTAKE 1, 2
Author(s) -
D'Elia Christopher F.,
DeBoer James A.
Publication year - 1978
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1978.tb00297.x
Subject(s) - ammonium , nitrogen , nitrate , biology , kinetics , algae , saturation (graph theory) , diel vertical migration , steady state (chemistry) , saturation vapor curve , botany , zoology , biochemistry , chemistry , enzyme , ecology , physics , mathematics , organic chemistry , quantum mechanics , combinatorics
Similar NH 4+ and NO 3 − .uptake kinetic patterns were observed in Neoagardhiella baileyi (Harvey ex Kiitzing) Wyinne & Taylor and Gracilaria foliifera (Forssk?l) Borgesen. NO 3 − was taken up in a rate‐sturating fashion described by the Michaelis‐Menten equation. NH 4+ uptake was multicomponent: a saturable component was accompanied by a diffusive or a high K component showing no evidence of saturation (at ≤50 μM [NH 4+ ]). Nitrogen starved plantsi(C/N atom ratios > ca. 10) showed higher transient rates of NH 4+ uptake at a given concentration than plants not N‐Iimited. Only plants with high N content exhibited diel changes inNH 4+ uptake rates, and showed transient rates of NH 4+ accumulation which did not greatly exceed the capacity to incorporate N in steady‐state growth. NH 4+ was preferred over NO 3− even in plants preconditioned on NO 3− as the sole N. source, NO 3− uptake was suppressed at 5μM [NH 4+ ], but simultaneous uptake occurred at unsurpressed rates at lower concentrations. Potential for N accumulation was greater via NH 4+ uptake than via NO 3− uptake. Changing capacity for NH 4+ uptake with N content appears to be a mechanism whereby excessive accumulation of N was avoided by N‐.satiated plants but a large accumulation was possible for N‐depleted plants.