Cytochrome P450 1A mRNA in the guppy Phalloceros caudimaculatus and response to beta-naphthoflavone and environmental samples

Abstract

The cytochrome P450 1A (CYP1A) mRNA is induced by environmental contaminants such as PAHs, PCBs and dioxins. The present study cloned the CYP1A transcript from the guppy Phalloceros caudimaculatus, which represents a potential fish for toxicological studies in South America. The newly identified CYP1A encodes a protein with 521 amino acids that shared 96–70% identity with other fishes. The characterization of organ- and time-dependent induction of CYP1A using RT-qPCR was evaluated after waterborne exposure to beta-naphthoflavone (BNF; 1μM). The minimum exposure time that elicited significant CYP1A induction was 1h for liver, gill, gut, brain, anal fin and fingerlings; 2h for dorsal fin; and 4h for kidney and tail fin. CYP1A tended to reach peak induction in the first few hours (4h–8h) of experiment in most organs, although levels remained induced until the end of the experiment (96h). Validation of CYP1A use in environmental sample was performed by exposing P. caudimaculatus to elutriate made from sediment of three streams located in adjacent areas of the Patos Lagoon Estuary (RS, Brazil). CYP1A in liver, gills and anal fin was induced by elutriate made from urban (S1) and industrial (S2) sites; and not induced by a reference site located 22 Km from potential contaminant sources, suggesting that environmental contamination plays a role in this induction. The results suggest that fins could be used for CYP1A biomarker analysis and employed in non-lethal biopsy methods for environmental monitoring. The responsiveness of the newly identified CYP1A to BNF and elutriate indicates that the guppy P. caudimaculatus could be used for environmental toxicology investigations in South American environments.