FN Archimer Export Format
PT J
TI Short-term temporal variability of ammonium and urea uptake by Alexandrium catenella (Dinophyta) in cultures
BT 
AF JAUZEIN, Cecile
   COLLOS, Yves
   GARCES, E
   VILA, M
   MASO, M
AS 1:1,3;2:1;3:2;4:2;5:2;
FF 1:PDG-DOP-LER-LERLR;2:;3:;4:;5:;
C1 Univ Montpellier 2, CNRS, IFREMER, Lab Ecosyst Lagunaires,UMR 5119, F-34059 Montpellier 5, France.
   CSIC, Inst Ciencias Mar, E-08003 Barcelona, Spain.
C2 UNIV MONTPELLIER, FRANCE
   CSIC, SPAIN
   IFREMER, FRANCE
SI SETE
   MONTPELLIER
SE PDG-DOP-LER-LERLR
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-europe
   copubli-univ-france
IF 2.811
TC 18
UR https://archimer.ifremer.fr/doc/2008/publication-6416.pdf
LA English
DT Article
DE ;Urea;Uptake kinetics;Temporal variability;Ammonium release;Ammonium;Alexandrium catenella
AB In batch cultures of four Mediterranean strains (from France, Italy, and Spain) of Alexandrium catenella (Whedon et Kof.) Balech growing on a daily light cycle, ammonium and urea uptake were estimated by the N-15 tracer technique. Ammonium uptake could be described by Michaelis-Menten kinetics along a substrate gradient of 0.1-10 mu gat N.L-1 for the four strains, while two different patterns were observed for urea uptake with Michaelis-Menten kinetics for one strain and linear kinetics for the others. In all cases, an increase in uptake rates with time was noted over the daylight period. This trend led to a net increase in the maximum uptake rate (V-max; for saturable kinetics) and in the initial slope alpha. For ammonium, V-max increased by a factor of 2-10 depending on the strain, and, for urea, the maximal uptake rates measured increased by a factor of 2-18. Temporal variations of half-saturation constants (K-s) for both nutrients did not show a clear trend. Increases in V-max and alpha showed an acclimation of the cells' uptake system over time to a N pulse, which may be explained by the light periodicity. For two strains, extensive ammonium release was observed during urea assimilation. This mechanism removes urea from the medium, so it is no longer available to other potential competitors, but supplies N back to the medium in the form of ammonium. From a methodological point of view, the phenomenon leads to considerable underestimates of the contribution of urea to phytoplankton growth.
PY 2008
PD OCT
SO Journal of Phycology
SN 0022-3646
PU Wiley / Blackwell
VL 44
IS 5
UT 000259866800005
BP 1136
EP 1145
DI 10.1111/j.1529-8817.2008.00570.x
ID 6416
ER

EF