Data/hora: 16/06/2024 03:52:51

Provedor de dados: 	88	
País: 	Brazil	
Título: 	Effects of different ammoniacal nitrogen sources on N-metabolism of the atmospheric bromeliad Tillandsia pohliana Mez	
Autores: 	TAMAKI,VÍVIAN; MERCIER,HELENICE.	
Data: 	2001-12-01	
Ano: 	2001	
Palavras-chave: 	Bromeliaceae NH3; NH4+ GS GDH-NADH.	
Resumo: 	Increasing levels of atmospheric ammonia from anthropogenic sources have become a serious problem for natural vegetation. Short-term effects of different ammoniacal sources on the N metabolism of Tillandsia pohliana, an atmospheric bromeliad, were investigated. One-year-old, aseptically grown plants were transferred to a modified Knudson medium lacking N for three weeks. Plants were subsequently transferred to Knudson media supplemented with 0.5, 1.0, or 1.5 mM of N in the forms of NH3 or NH4+ as the sole N source. The activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH-NADH) were determined after 40 h. The GS activity was stimulated significantly by increasing the levels of the gaseous form. The GDH-NADH activity increased significantly under increasing N concentrations with NH3, while no significant differences were observed with NH4+ as a N source. These results may reflect a faster NH3 absorption by T. pohliana compared to NH4+ uptake. The increased activity of GDH-NADH in NH3 treatment may play a role in protecting the cells from the toxic effects of increased endogenous level of free ammonium. A raise in the concentration of N, especially in the form of NH3, greatly increased the content of free amino acids and soluble proteins. A possible utilisation of T. pohliana to evaluate the changes of atmospheric gaseous ammonia is proposed.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042001000400006	
Editor: 	Sociedade Botânica de São Paulo	
Relação: 	10.1590/S0100-84042001000400006	
Formato: 	text/html	
Fonte: 	Brazilian Journal of Botany  v.24 n.4 2001	
Fonte: 	info:eu-repo/semantics/openAccess