Journal of Environmental Biology

Development of quantitative RNA biomarkers for detecting

dioxin-like and estrogenic pollutants in Costa Rican native fish species

A. Navarro¹, F. Mena² ,M. Casado¹, M. Pinnock², E. de la Cruz², C. Barata¹* and B. Pi?a²

¹Department of Environmental Chemistry, ID?A-CSIC, JordiGirona 18, 08034 Barcelona, Spain

²Central American InstituteforStudiesonToxic Substances / Instituto Regional de Estudios en Sustancias T?xicas (IRET)

Universidad Nacional, Campus Omar Dengo, Heredia, 86-3000, Costa Rica

*Corresponding Author E-mail: cbmqam@cid.csic.es

 Publication Data

Paper received:

28 November 2012

Revised received:

10 May 2013

Accepted:

05 September 2013

Abstract

Monitoring the environmental impact on native species is crucial for the correct management of tropical ecosystems. The Costa Rican fish Parachromis dovii (Cichlidae) and Poecilia gillii (Poecillidae) were used as sentinel species for freshwater bodies under considerable pressure by intensive agriculture Cichlidae development. Suitable qRT-PCR probes for the quantification of hepatic mRNA levels of two stress-related genes ?vitellogen in (estrogenic effects) and? cytochrome P4501A (CYP1A, dioxin-like compounds) ? for both species were designed and validated in experimental treatments with model effectors (17β-estradiol and β-naphtoflavone, respectively), demonstrating their usefulness as markers of exposure to these two kinds of pollutants. Analysis of fish transplanted across pesticide contaminated sites near Palo Verde National Park, Pacific Coast of Costa Rica did show significant changes on hepatic Cyp1A in both species. In P. dovii, Cyp1A levels were enhanced in Barbubal and in the impacted Cabuyo sites in the rainy season whereas in P. gillii fish Cyp1A transcripts were down-regulated differently across rainy and dry seasons. Vitellogen in mRNA levels in P. gillii varied between males and females with males showing always low values which indicated no estrogenic effects. Within females, vitellogenin levels varied over 100,000 fold depending on their maturation stage, further demonstrating the ability of the method to monitor changes (natural or induced) in the reproductive system of the fish. 

Key words

Biomarker, Endocrine disruption, EROD, Fish, Pesticides, Tropical

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