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Induction of cytochrome P4501A isoform in Xenopus laevis
is a valid tool for monitoring the exposure to benzo[a]pyrene
A. Colombo, P. Bonfanti, M. Ciccotelli, M. Doldi,
N. Dell'Orto & M. Camatini*
Dipartimento di Scienze dell'Ambiente e del Territorio,
Universitá di Milano, Via Emanueli 15, 20126 Milano,
Italy (*author for correspondence)
Received 31 July 1995; accepted in
revised form April 1996
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Abstract
In mammals polycyclic aromatic hydrocarbons (PAW) are
metabolized by the enzymes of the cytochrome P-4501A family expressed
in specific cell types. Recently the expression of both CYP1A1 and
CYP1A2 transcripts has been demonstrated in liver of 3-MC treated
rainbow trout. In the present study induction of CYP1A was investigated
by immunoblot analysis in adults and embryos of Xenopus laevis
treated wit benzo[a]pyrene (B[a]P). The data obtained showed tat
polyclonal antibodies, raised against rat cytochrome P-4501A1, recognized
a single band with apparent molecular weight between 55 kDa and
66 kDa as rat CYP1A both in adult liver microsomes and embryo homogenates.
The assessment of the metabolic activity, performed with ethyl acetate
extraction of treated embryo homogenate demonstrated that X.
laevis early developmental stages (stage 35 and stage 48) are
competent to convert B[a]P into its metabolites. These results suggest
that X. laevis is a sensitive model to evaluate fresh water
pollution.
Keywords: Xenopus laevis embryos, benzo[a]pyrene. cytochrome
P450
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