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ELEVATED LEVELS OF MULTIPLE CYTOCHROME P450 FORMS IN TILAPIA FROM BILLINGS RESERVOIR-SAO PAULO, BRAZIL. (R827102)
Citation:
Bainy, A., B. R. Woodin, AND J. J. Stegeman. ELEVATED LEVELS OF MULTIPLE CYTOCHROME P450 FORMS IN TILAPIA FROM BILLINGS RESERVOIR-SAO PAULO, BRAZIL. (R827102). AQUATIC TOXICOLOGY. Elsevier Science Ltd, New York, NY, 44(4):289-305, (1999).
Description:
Cytochrome P4501A (CYP1A) levels in tissues of fish inhabiting polluted areas have been used extensively in biomonitoring studies in Europe and North America. However, little information is available about the extent of CYP1A expression in fish from South American waters, nor on the expression of other CYP proteins in fish from polluted sites. The content of total cytochrome P450 and b5 and of proteins cross-reactive with antibodies to teleost (scup) CYP1A-, CYP2B- and CYP3A-like proteins, as well as rates of alkoxy-resorufin-O-dealkylases (ARODs) with methoxy-, ethoxy-, pentoxy- and benzyloxyresorufin substrates, were analyzed in liver and kidney microsomes from tilapia (Oreochromis niloticus) from a reference site (Estação de Piscicultura de Pindamonhangaba, São Paulo) and a polluted site (Billings Reservoir, São Paulo, Brazil). Levels of total microsomal P450 and b5 were elevated 1.8- and 3.3-fold, respectively, in liver and 4.3- and 2.4-fold in kidney of tilapia from Billings Reservoir. Rates of all four ARODs and the levels of CYP1A-, CYP2B- and CYP3A-cross-reactive proteins were elevated in liver and kidney of fish from Billings Reservoir compared to those in reference fish. Hepatic microsomal EROD and MROD were about 20-fold greater and levels of 1A protein more than 400-fold greater in Billings fish. Antibodies to teleost CYP1A and putative CYP3A recognized single bands while Pab to the scup CYP2B-like protein recognized three protein bands in liver and kidney. This suggests that there are multiple CYP2B-like proteins expressed in tilapia. Immunohistochemical analysis also indicated increased expression of CYP1A cross-reactive proteins in cells of liver, gill, kidney and heart. The apparent induction of CYP1A probably reflects the exposure to aryl hydrocarbon receptor agonists present as pollutants in the Billings Reservoir. Elevated levels of the other CYP forms in tissues of tilapia from Billings Reservoir could be related either to the presence of pollutants or to some natural compound present in the diet, since tilapia is known as an herbivorous species.
Author Keywords: Cytochrome P450; Tilapia; Billings reservoir; CYP forms; ARODs