Unidirectional Sodium Fluxes and Gill CYP1A Induction in an Amazonian Fish (Hyphessobrycon erythrostigma) Exposed to a Surfactant and to Crude Oil A. Y. O. Matsuo, R. M. Duarte, A. L. Val Instituto Nacional de Pesquisas da Amazônia, INPA, Laboratório de Ecofisiologia e Evolução Molecular, Avenida André Araújo, 2936, Aleixo, Manaus, Amazonas, 69083-000, Brazil Received: 4 April 2005/Accepted: 16 August 2005 Correspondence to: A. Y. O. Matsuo, 700 Warren Road, #17-3F, Ithaca, NY 14850, USA Bull. Environ. Contam. Toxicol. (2005) 75:851–858 © 2005 Springer Science+Business Media, Inc. DOI: 10.1007/s00128-005-0828-3 851