Biomarkers of Organic Contamination in the South American Fish Poecilia vivipara and Jenynsia multidentata

Abstract

South American cyprinodontiform fish are potential candidates to be used as model biomarker species of exposure in environmental toxicology. The aim of this study was to identify molecular and biochemical biomarkers of pollution using Poecilia vivipara (Poecilidae) and Jenynsia multidentata (Anablepidae). Partial nucleotide sequences for cytochrome P-450 1A (CYP1A), a classical biomarker of exposure to organic contaminants in fish, were identified in P. vivipara and J. multidentata (approximately 650 nucleotides) using degenerated primers and polymerase chain reaction (PCR). These sequences shared approximately 90% identity in the predicted amino acid sequence with the corresponding CYP1A region of Fundulus heteroclitus. Real-time quantitative PCR (RT-qPCR) analysis confirmed that CYP1A transcription was markedly induced in the liver and gills of J. multidentata (approximately185-fold and 20-fold, respectively) and P. vivipara (122-fold and 739-fold, respectively) 24 h after exposure to 1 μM synthetic CYP1A inducer β-naphthoflavone (BNF). At 24 h after injection with 1 μg/g environmental carcinogenic contaminant benzo[a]pyrene (BaP), a decreased total antioxidant capacity against peroxyl radicals was observed both in liver of J. multidentata and gills of P. vivipara. BaP injection in both fish did not produce changes in lipid peroxide (thiobarbituric acid-reactive substances, TBARS) levels, suggesting an absence of an oxidative stress condition. The newly identified CYP1A may thus serve as general biomarker of exposure to organic contaminant in future studies using P. vivipara and J. multidentata. Data also indicate the importance of species-specific differences in biomarker responses in these South American cyprinodontiform fish, suggesting distinct resistance/susceptibility properties to polycyclic aromatic hydrocarbons.

Acknowledgments

This study was supported in part by Brazilian INCT-TA (CNPq 573949/2008-5) and NIH grants to JJS (the Superfund Basic Research Program 5-P42-ES007381 and R01-ES015912). JZ was a guest student at the Woods Hole Oceanographic Institution and was supported by a CAPES PhD Fellowship and CNPq PhD Sandwich Fellowship, Brazil. ACDB and JMM are recipients of a CNPQ Productivity Fellowship, Brazil. RSF is recipient of the CNPQ-PIBIC fellowship, Brazil. Study sponsors had no involvement in the studies reported here or in the decision to submit this article for publication. Thank to J. J. Mattos, M. S. Sopezki, F. S. Guimarães, J. L. R. Scaini, S. I. M. Abril, C. Rodriguez, and E. P. Colares for their assistance in the experimental procedures.