ISSN:
1573-5117
Keywords:
Melosira italica
;
diatoms
;
uptake kinetics
;
nitrogen organic compounds
;
urea
;
phytoplankton physiology
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The kinetic parameters Km and Vmax for urea uptake by Melosira italica were determined at 160 µeinsteins m−2 s−1 and in the dark. The transport systems showed an affinity for the substrate and a storing capacity in the dark (Km = 65.07 µM; Vmax = 2.18 nmoles 105 cells −1 h−1) greater than under 160 µE m−2 s −1 (Km = 111.2 µM; Vmax = 1.11 nmoles 105 cells−1 h−1). Similarly, a reduction in consumption rate of urea under increasing photon flux densities was observed. The use of an inhibitor (potassium cyanide) indicated that the uptake process requires metabolic energy. That urea transport is more important in darkness, may constitute a survival strategy in which this compound is utilized by cells mainly during heterotrophic growth.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00006577
Permalink
