Sabiia Seb
        Busca avançada

Botão Atualizar

Botão Atualizar

Registro completo
Provedor de dados:  ArchiMer
País:  France
Título:  Short-term temporal variability of ammonium and urea uptake by Alexandrium catenella (Dinophyta) in cultures
Autores:  Jauzein, Cecile
Collos, Yves
Garces, E
Vila, M
Maso, M
Data:  2008-10
Ano:  2008
Palavras-chave:  Urea
Uptake kinetics
Temporal variability
Ammonium release
Alexandrium catenella
Resumo:  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.
Tipo:  Text
Idioma:  Inglês

Editor:  Wiley / Blackwell
Formato:  application/pdf
Fonte:  Journal of Phycology (0022-3646) (Wiley / Blackwell), 2008-10 , Vol. 44 , N. 5 , P. 1136-1145
Direitos:  2009 Phycological Society of America,Wiley-Blackwell Publishing

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC:

Valid HTML 4.01 Transitional